WorldWideScience

Sample records for surface downward longwave

  1. Observational Characterization of the Downward Atmospheric Longwave Radiation at the Surface in the City of São Paulo

    NARCIS (Netherlands)

    Wilde Barbaro, E.; Oliveira, A.P.; Soares, J.; Codato, G.; Ferreira, M.J.; Mlakar, P.; Boznar, M.Z.; Escobedo, J.

    2010-01-01

    This work describes the seasonal and diurnal variations of downward longwave atmospheric irradiance (LW) at the surface in São Paulo, Brazil, using 5-min-averaged values of LW, air temperature, relative humidity, and solar radiation observed continuously and simultaneously from 1997 to 2006 on a

  2. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Science.gov (United States)

    Gubler, S.; Gruber, S.; Purves, R. S.

    2012-06-01

    As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR) and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR). In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB) stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM) in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night. We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD) and the relative root mean squared deviance (RMSD) of the clear-sky global SDR scatter between between -2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations to local conditions

  3. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Directory of Open Access Journals (Sweden)

    S. Gubler

    2012-06-01

    Full Text Available As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR. In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night.

    We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD and the relative root mean squared deviance (RMSD of the clear-sky global SDR scatter between between −2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations

  4. Comparison of the sensitivity of surface downward longwave radiation to changes in water vapor at two high elevation sites

    International Nuclear Information System (INIS)

    Chen, Yonghua; Naud, Catherine M; Rangwala, Imtiaz; Landry, Christopher C; Miller, James R

    2014-01-01

    Among the potential reasons for enhanced warming rates in many high elevation regions is the nonlinear relationship between surface downward longwave radiation (DLR) and specific humidity (q). In this study we use ground-based observations at two neighboring high elevation sites in Southwestern Colorado that have different local topography and are 1.3 km apart horizontally and 348 m vertically. We examine the spatial consistency of the sensitivities (partial derivatives) of DLR with respect to changes in q, and the sensitivities are obtained from the Jacobian matrix of a neural network analysis. Although the relationship between DLR and q is the same at both sites, the sensitivities are higher when q is smaller, which occurs more frequently at the higher elevation site. There is a distinct hourly distribution in the sensitivities at both sites especially for high sensitivity cases, although the range is greater at the lower elevation site. The hourly distribution of the sensitivities relates to that of q. Under clear skies during daytime, q is similar between the two sites, however under cloudy skies or at night, it is not. This means that the DLR–q sensitivities are similar at the two sites during daytime but not at night, and care must be exercised when using data from one site to infer the impact of water vapor feedbacks at another site, particularly at night. Our analysis suggests that care should be exercised when using the lapse rate adjustment to infill high frequency data in a complex topographical region, particularly when one of the stations is subject to cold air pooling as found here. (letter)

  5. Comparison of the Sensitivity of Surface Downward Longwave Radiation to Changes in Water Vapor at Two High Elevation Sites

    Science.gov (United States)

    Chen, Yonghua; Naud, Catherine M.; Rangwala, Imtiaz; Landry, Christopher C.; Miller, James R.

    2014-01-01

    Among the potential reasons for enhanced warming rates in many high elevation regions is the nonlinear relationship between surface downward longwave radiation (DLR) and specific humidity (q). In this study we use ground-based observations at two neighboring high elevation sites in Southwestern Colorado that have different local topography and are 1.3 kilometers apart horizontally and 348 meters vertically. We examine the spatial consistency of the sensitivities (partial derivatives) of DLR with respect to changes in q, and the sensitivities are obtained from the Jacobian matrix of a neural network analysis. Although the relationship between DLR and q is the same at both sites, the sensitivities are higher when q is smaller, which occurs more frequently at the higher elevation site. There is a distinct hourly distribution in the sensitivities at both sites especially for high sensitivity cases, although the range is greater at the lower elevation site. The hourly distribution of the sensitivities relates to that of q. Under clear skies during daytime, q is similar between the two sites, however under cloudy skies or at night, it is not. This means that the DLR-q sensitivities are similar at the two sites during daytime but not at night, and care must be exercised when using data from one site to infer the impact of water vapor feedbacks at another site, particularly at night. Our analysis suggests that care should be exercised when using the lapse rate adjustment to infill high frequency data in a complex topographical region, particularly when one of the stations is subject to cold air pooling as found here.

  6. The Global Character of the Flux of Downward Longwave Radiation

    Science.gov (United States)

    Stephens, Graeme L.; Wild, Martin; Stackhouse, Paul W., Jr.; L'Ecuyer, Tristan; Kato, Seiji; Henderson, David S.

    2012-01-01

    Four different types of estimates of the surface downwelling longwave radiative flux (DLR) are reviewed. One group of estimates synthesizes global cloud, aerosol, and other information in a radiation model that is used to calculate fluxes. Because these synthesis fluxes have been assessed against observations, the global-mean values of these fluxes are deemed to be the most credible of the four different categories reviewed. The global, annual mean DLR lies between approximately 344 and 350 W/sq m with an error of approximately +/-10 W/sq m that arises mostly from the uncertainty in atmospheric state that governs the estimation of the clear-sky emission. The authors conclude that the DLR derived from global climate models are biased low by approximately 10 W/sq m and even larger differences are found with respect to reanalysis climate data. The DLR inferred from a surface energy balance closure is also substantially smaller that the range found from synthesis products suggesting that current depictions of surface energy balance also require revision. The effect of clouds on the DLR, largely facilitated by the new cloud base information from the CloudSat radar, is estimated to lie in the range from 24 to 34 W/sq m for the global cloud radiative effect (all-sky minus clear-sky DLR). This effect is strongly modulated by the underlying water vapor that gives rise to a maximum sensitivity of the DLR to cloud occurring in the colder drier regions of the planet. The bottom of atmosphere (BOA) cloud effect directly contrast the effect of clouds on the top of atmosphere (TOA) fluxes that is maximum in regions of deepest and coldest clouds in the moist tropics.

  7. Predicting Downward Longwave Radiation for Various Land Use in All-Sky Condition: Northeast Florida

    Directory of Open Access Journals (Sweden)

    Chi-Han Cheng

    2014-01-01

    Full Text Available Accurate estimate of the surface longwave radiation is important for the surface radiation budget, which in turn controls evaporation and sensible heat fluxes. Regional land use changes can impact local weather conditions; for example, heterogeneous land use patterns and temporal changes in atmospheric circulation patterns would affect air temperature and water vapor pressure, which are more commonly used as inputs in existing models for estimating downward longwave radiation (LWd. In this study, first, we analyzed the cloud cover and land use covers impacts on LWd. Next, LWd on all-sky conditions were developed by using the existing land use-adapted model and cloud cover data from the region of Saint Johns River Water Management District (SJRWMD, FL. The results show that factors, such as, seasonal effects, cloud cover, and land use, are of importance in the estimation of LWd and they cannot be ignored when developing a model for LWd prediction. The all-sky land use-adapted model with all factors taken into account performs better than other existing models statistically. The results of the statistical analyses indicated that the BIAS, RMSE, MAE, and PMRE are −0.18 Wm−2, 10.81 Wm−2, 8.00 Wm−2, and 2.30%; −2.61 Wm−2, 14.45 Wm−2, 10.64 Wm−2, and 3.19%; −0.07 Wm−2, 10.53 Wm−2, 8.03 Wm−2, and 2.27%; and −0.62 Wm−2, 13.97 Wm−2, 9.76 Wm−2, and 2.87% for urban, rangeland, agricultural, and wetland areas, respectively.

  8. Using Satellites to Investigate the Sensitivity of Longwave Downward Radiation to Water Vapor at High Elevations

    Science.gov (United States)

    Naud, Catherine M.; Miller, James R.; Landry, Chris

    2012-01-01

    Many studies suggest that high-elevation regions may be among the most sensitive to future climate change. However, in situ observations in these often remote locations are too sparse to determine the feedbacks responsible for enhanced warming rates. One of these feedbacks is associated with the sensitivity of longwave downward radiation (LDR) to changes in water vapor, with the sensitivity being particularly large in many high-elevation regions where the average water vapor is often low. We show that satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) can be used to expand the current ground-based observational database and that the monthly averaged clear-sky satellite estimates of humidity and LDR are in good agreement with the well-instrumented Center for Snow and Avalanche Studies ground-based site in the southwestern Colorado Rocky Mountains. The relationship between MODIS-retrieved precipitable water vapor and surface specific humidity across the contiguous United States was found to be similar to that previously found for the Alps. More important, we show that satellites capture the nonlinear relationship between LDR and water vapor and confirm that LDR is especially sensitive to changes in water vapor at high elevations in several midlatitude mountain ranges. Because the global population depends on adequate fresh water, much of which has its source in high mountains, it is critically important to understand how climate will change there. We demonstrate that satellites can be used to investigate these feedbacks in high-elevation regions where the coverage of surface-based observations is insufficient to do so.

  9. Comparison of observed and modeled cloud-free longwave downward radiation (2010–2016 at the high mountain BSRN Izaña station

    Directory of Open Access Journals (Sweden)

    R. D. García

    2018-06-01

    Full Text Available A 7-year (2010–2016 comparison study between measured and simulated longwave downward radiation (LDR under cloud-free conditions was performed at the Izaña Atmospheric Observatory (IZO, Spain. This analysis encompasses a total of 2062 cases distributed approximately evenly between day and night. Results show an excellent agreement between Baseline Surface Radiation Network (BSRN measurements and simulations with libRadtran V2.0.1 and MODerate resolution atmospheric TRANsmission model (MODTRAN V6 radiative transfer models (RTMs. Mean bias (simulated − measured of  <  1.1 % and root mean square of the bias (RMS of  <  1 % are within the instrumental error (2 %. These results highlight the good agreement between the two RTMs, proving to be useful tools for the quality control of LDR observations and for detecting temporal drifts in field instruments. The standard deviations of the residuals, associated with the RTM input parameters uncertainties are rather small, 0.47 and 0.49 % for libRadtran and MODTRAN, respectively, at daytime, and 0.49 to 0.51 % at night-time. For precipitable water vapor (PWV  >  10 mm, the observed night-time difference between models and measurements is +5 W m−2 indicating a scale change of the World Infrared Standard Group of Pyrgeometers (WISG, which serves as reference for atmospheric longwave radiation measurements. Preliminary results suggest a possible impact of dust aerosol on infrared radiation during daytime that might not be correctly parametrized by the models, resulting in a slight underestimation of the modeled LDR, of about −3 W m−2, for relatively high aerosol optical depth (AOD  >  0.20.

  10. ENSO surface longwave radiation forcing over the tropical Pacific

    Directory of Open Access Journals (Sweden)

    K. G. Pavlakis

    2007-01-01

    Full Text Available We have studied the spatial and temporal variation of the surface longwave radiation (downwelling and net over a 21-year period in the tropical and subtropical Pacific Ocean (40 S–40 N, 90 E–75 W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database and reanalysis data from NCEP/NCAR (acronyms explained in main text, for the key atmospheric and surface input parameters. An excellent correlation was found between the downwelling longwave radiation (DLR anomaly and the Niño-3.4 index time-series, over the Niño-3.4 region located in the central Pacific. A high anti-correlation was also found over the western Pacific (15–0 S, 105–130 E. There is convincing evidence that the time series of the mean downwelling longwave radiation anomaly in the western Pacific precedes that in the Niño-3.4 region by 3–4 months. Thus, the downwelling longwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to asses whether or not El Niño or La Niña conditions prevail. Over the Niño-3.4 region, the mean DLR anomaly values range from +20 Wm−2 during El Niño episodes to −20 Wm−2 during La Niña events, while over the western Pacific (15–0 S, 105–130 E these values range from −15 Wm−2 to +10 Wm−2, respectively. The long- term average (1984–2004 distribution of the net downwelling longwave radiation at the surface over the tropical and subtropical Pacific for the three month period November-December-January shows a net thermal cooling of the ocean surface. When El Niño conditions prevail, the thermal radiative cooling in the central and south-eastern tropical Pacific becomes weaker by 10 Wm−2 south of the equator in the central Pacific (7–0 S, 160–120 W for the three-month period of NDJ, because the DLR increase is larger than the increase in surface thermal emission. In contrast, the

  11. Relationship between ice water path and downward longwave radiation for clouds optically thin in the infrared: Observations and model calculations

    Science.gov (United States)

    Uttal, Taneil; Matrosov, Sergey Y.; Snider, Jack B.; Kropfli, Robert A.

    1994-01-01

    A vertically pointing 3.2-cm radar is used to observe altostratus and cirrus clouds as they pass overhead. Radar reflectivities are used in combination with an empirical Z(sub i)-IWC (ice water content) relationship developed by Sassen (1987) to parameterize IWC, which is then integrated to obtain estimates of ice water path (IWP). The observed dataset is segregated into all-ice and mixed-phase periods using measurements of integrated liquid water paths (LWP) detected by a collocated, dual-channel microwave radiometer. The IWP values for the all ice periods are compared to measurements of infrared (IR) downward fluxes measured by a collocated narrowband (9.95-11.43 microns) IR radiometer, which results in scattergrams representing the observed dependence of IR fluxes on IWP. A two-stream model is used to calculate the infrared fluxes expected from ice clouds with boundary conditions specified by the actual clouds, and similar curves relating IWP and infrared fluxes are obtained. The model and observational results suggest that IWP is one of the primary controls on infrared thermal fluxes for ice clouds.

  12. Observed Screen (Air) and GCM Surface/Screen Temperatures: Implications for Outgoing Longwave Fluxes at the Surface.

    Science.gov (United States)

    Garratt, J. R.

    1995-05-01

    There is direct evidence that excess net radiation calculated in general circulation models at continental surfaces [of about 11-17 W m2 (20%-27%) on an annual ~1 is not only due to overestimates in annual incoming shortwave fluxes [of 9-18 W m2 (6%-9%)], but also to underestimates in outgoing longwave fluxes. The bias in the outgoing longwave flux is deduced from a comparison of screen-air temperature observations, available as a global climatology of mean monthly values, and model-calculated surface and screen-air temperatures. An underestimate in the screen temperature computed in general circulation models over continents, of about 3 K on an annual basis, implies an underestimate in the outgoing longwave flux, averaged in six models under study, of 11-15 W m2 (3%-4%). For a set of 22 inland stations studied previously, the residual bias on an annual basis (the residual is the net radiation minus incoming shortwave plus outgoing longwave) varies between 18 and 23 W m2 for the models considered. Additional biases in one or both of the reflected shortwave and incoming longwave components cannot be ruled out.

  13. Downward velocity distribution of free surface vortex in a cylindrical vessel

    International Nuclear Information System (INIS)

    Ohguri, Youhei; Monji, Hideaki; Kamide, Hideki

    2008-01-01

    The aim of this study is to reveal the basic flow characteristics, especially downward velocity, of the free surface vortex. The flow field at the vertical cross section in a cylindrical vessel was measured by using PIV. The measurement results showed the inclined vortex center due to the un-axisymmetric structure of the vessel. Therefore, the maximum downward velocity on the cross section was discussed with the depth. The relation between the maximum downward velocity and the depth showed the tendency where the downward velocity increased with the depth non-linearly. By using dye, the downward velocity was also measured but its results showed a little difference from that by PIV. (author)

  14. Estimation of Downwelling Surface Longwave Radiation under Heavy Dust Aerosol Sky

    Directory of Open Access Journals (Sweden)

    Chunlei Wang

    2017-02-01

    Full Text Available The variation of aerosols, especially dust aerosol, in time and space plays an important role in climate forcing studies. Aerosols can effectively reduce land surface longwave emission and re-emit energy at a colder temperature, which makes it difficult to estimate downwelling surface longwave radiation (DSLR with satellite data. Using the latest atmospheric radiative transfer code (MODTRAN 5.0, we have simulated the outgoing longwave radiation (OLR and DSLR under different land surface types and atmospheric profile conditions. The results show that dust aerosol has an obvious “warming” effect to longwave radiation compared with other aerosols; that aerosol longwave radiative forcing (ALRF increased with the increasing of aerosol optical depth (AOD; and that the atmospheric water vapor content (WVC is critical to the understanding of ALRF. A method is proposed to improve the accuracy of DSLR estimation from satellite data for the skies under heavy dust aerosols. The AOD and atmospheric WVC under cloud-free conditions with a relatively simple satellite-based radiation model yielding the high accurate DSLR under heavy dust aerosol are used explicitly as model input to reduce the effects of dust aerosol on the estimation of DSLR. Validations of the proposed model with satellites data and field measurements show that it can estimate the DSLR accurately under heavy dust aerosol skies. The root mean square errors (RMSEs are 20.4 W/m2 and 24.2 W/m2 for Terra and Aqua satellites, respectively, at the Yingke site, and the biases are 2.7 W/m2 and 9.6 W/m2, respectively. For the Arvaikheer site, the RMSEs are 23.2 W/m2 and 19.8 W/m2 for Terra and Aqua, respectively, and the biases are 7.8 W/m2 and 10.5 W/m2, respectively. The proposed method is especially applicable to acquire relatively high accurate DSLR under heavy dust aerosol using MODIS data with available WVC and AOD data.

  15. Improving representation of canopy temperatures for modeling subcanopy incoming longwave radiation to the snow surface

    Science.gov (United States)

    Webster, Clare; Rutter, Nick; Jonas, Tobias

    2017-09-01

    A comprehensive analysis of canopy surface temperatures was conducted around a small and large gap at a forested alpine site in the Swiss Alps during the 2015 and 2016 snowmelt seasons (March-April). Canopy surface temperatures within the small gap were within 2-3°C of measured reference air temperature. Vertical and horizontal variations in canopy surface temperatures were greatest around the large gap, varying up to 18°C above measured reference air temperature during clear-sky days. Nighttime canopy surface temperatures around the study site were up to 3°C cooler than reference air temperature. These measurements were used to develop a simple parameterization for correcting reference air temperature for elevated canopy surface temperatures during (1) nighttime conditions (subcanopy shortwave radiation is 0 W m-2) and (2) periods of increased subcanopy shortwave radiation >400 W m-2 representing penetration of shortwave radiation through the canopy. Subcanopy shortwave and longwave radiation collected at a single point in the subcanopy over a 24 h clear-sky period was used to calculate a nighttime bulk offset of 3°C for scenario 1 and develop a multiple linear regression model for scenario 2 using reference air temperature and subcanopy shortwave radiation to predict canopy surface temperature with a root-mean-square error (RMSE) of 0.7°C. Outside of these two scenarios, reference air temperature was used to predict subcanopy incoming longwave radiation. Modeling at 20 radiometer locations throughout two snowmelt seasons using these parameterizations reduced the mean bias and RMSE to below 10 W m s-2 at all locations.

  16. Experimental investigation of pool boiling heat transfer and critical heat flux on a downward facing surface

    International Nuclear Information System (INIS)

    Gocmanac, M.; Luxat, J.C.

    2012-01-01

    A separate effects experimental study of heat transfer and Critical Heat Flux (CHF) on a downward facing plate in subcooled water pool boiling is described. Two geometries of downwards facing surfaces are studied. The first is termed the 'confined' study in which bubble motion is restricted to the heated surface. The second is termed the 'unconfined' study where individual bubbles are free to move along the heated surface and vent in any direction. The method used in the confined study is novel and involves the placement of a lip surrounding the heated surface. The CHF as a function of angle of inclination of the surface is presented and is in good agreement with other experimental data from somewhat different test geometries. (author)

  17. An analytic model of pool boiling critical heat flux on an immerged downward facing curved surface

    International Nuclear Information System (INIS)

    He, Hui; Pan, Liang-ming; Wu, Yao; Chen, De-qi

    2015-01-01

    Highlights: • Thin liquid film and supplement of liquid contribute to the CHF. • CHF increases from the bottom to the upper of the lowerhead. • Evaporation of thin liquid film is dominant nearby bottom region. • The subcooling has significant effects on the CHF. - Abstract: In this paper, an analytical model of the critical heat flux (CHF) on the downward facing curved surface for pool boiling has been proposed, which hypothesizes that the CHF on the downward facing curved is composed of two parts, i.e. the evaporation of the thin liquid film underneath the elongated bubble adhering to the lower head outer surface and the depletion of supplement of liquid due to the relative motion of vapor bubbles along with the downward facing curved. The former adopts the Kelvin–Helmholtz instability analysis of vapor–liquid interface of the vapor jets which penetrating in the thin liquid film. When the heat flux closing to the CHF point, the vapor–liquid interface becomes highly distorted, which block liquid to feed the thin liquid film and the thin liquid film will dry out gradually. While the latter considers that the vapor bubbles move along with the downward facing curved surface, and the liquid in two-phase boundary layer enter the liquid film that will be exhausted when the CHF occurs. Based on the aforementioned mechanism and the energy balance between the thin liquid film evaporation and water feeding, and taking the subcooling of the bulk water into account, the mathematic model about the downward facing curved surface CHF has been proposed. The CHF of the downward facing curved surface for pool boiling increases along with the downward facing orientation except in the vicinity of bottom center region, because in this region the vapor bubble almost stagnates and the evaporation of the thin liquid film is dominant. In addition, the subcooling has significant effect on the CHF. Comparing the result of this model with the published experimental results show

  18. Clear-Sky Longwave Irradiance at the Earth's Surface--Evaluation of Climate Models.

    Science.gov (United States)

    Garratt, J. R.

    2001-04-01

    An evaluation of the clear-sky longwave irradiance at the earth's surface (LI) simulated in climate models and in satellite-based global datasets is presented. Algorithm-based estimates of LI, derived from global observations of column water vapor and surface (or screen air) temperature, serve as proxy `observations.' All datasets capture the broad zonal variation and seasonal behavior in LI, mainly because the behavior in column water vapor and temperature is reproduced well. Over oceans, the dependence of annual and monthly mean irradiance upon sea surface temperature (SST) closely resembles the observed behavior of column water with SST. In particular, the observed hemispheric difference in the summer minus winter column water dependence on SST is found in all models, though with varying seasonal amplitudes. The analogous behavior in the summer minus winter LI is seen in all datasets. Over land, all models have a more highly scattered dependence of LI upon surface temperature compared with the situation over the oceans. This is related to a much weaker dependence of model column water on the screen-air temperature at both monthly and annual timescales, as observed. The ability of climate models to simulate realistic LI fields depends as much on the quality of model water vapor and temperature fields as on the quality of the longwave radiation codes. In a comparison of models with observations, root-mean-square gridpoint differences in mean monthly column water and temperature are 4-6 mm (5-8 mm) and 0.5-2 K (3-4 K), respectively, over large regions of ocean (land), consistent with the intermodel differences in LI of 5-13 W m2 (15-28 W m2).

  19. Uncertainty in regional and zonal monthly mean downward surface irradiances from Edition 4.0 CERES Energy Balanced and Filled (EBAF) data product

    Science.gov (United States)

    Kato, S.; Rutan, D. A.; Rose, F. G.; Loeb, N. G.

    2017-12-01

    The surface of the Earth receives solar radiation (shortwave) and emission from the atmosphere (longwave). At a global and annual mean approximately 12% of solar radiation incident on the surface is reflected and the rest is absorbed by the surface. The surface emits radiation proportional to the forth power of the temperature. Although the uncertainty in global and annual mean surface irradiances is estimated in earlier studies (Zhang et al. 1995, 2004; L'Ecuyer et al. 2008; Stephens et al. 2012; Kato et al. 2012), only a few studies estimated the uncertainty in computed surface irradiances at smaller spatial and temporal scales (Zhang et al. 1995, 2004; Kato et al. 2012). We use surface observations at 46 buoys and 36 land sites and newly released the Edition 4.0 Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF)-surface data product to estimate the uncertainty in regional and zonal monthly mean downward shortwave and longwave surface irradiances. The root-mean-square difference of monthly mean computed and observed irradiances is used for the regional uncertainty. The uncertainty is separated into bias and spatially random components. The random component decreases when irradiances are averaged over a larger area, nearly inversely proportional to the number of surface observation sites. The presentation provides the uncertainty in the regional and zonal monthly mean downward surface irradiances over ocean and land. ReferencesKato, S. and N.G.Loeb, D. A.Rutan, F. G. Rose, S. Sun-Mack,W.F.Miller, and Y. Chen, 2012. Surv. Geophys., 33, 395-412, doi:10.1007/s10712-012-9179-x. L'Ecuyer, T. S., N. B. Wood, T. Haladay, G. L. Stephens, and P. W. Stackhouse Jr., 2008, J. Geophys. Res., 113, D00A15, doi:10.1029/2008JD009951. Stephens, G. L. and Coauthors, 2012, Nat. Geosci., 5, 691-696, doi:10.1038/ngeo1580. Zhang, Y., W. B. Rossow, A. A. Lacis, V. Oinas, and M. I. Mishchenko, 2004, J. Geophys. Res., 109, D19105, doi:10.1029/2003JD

  20. Heat transfer effect of an extended surface in downward-facing subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Abdul R., E-mail: khan@vis.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Erkan, Nejdet, E-mail: erkan@vis.t.u-tokyo.ac.jp [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki, 319-1188 (Japan); Okamoto, Koji, E-mail: okamoto@n.t.u-tokyo.ac.jp [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki, 319-1188 (Japan)

    2015-12-15

    Highlights: • Compare downward-facing flow boiling results from bare and extended surfaces. • Upstream and downstream temperatures were measured on the extended surface. • Downstream temperatures exceed upstream temperatures for all flow rates. • Bubble accumulation occurs downstream on extended surface. • Extended surface heat transfer lower than bare surface as flow rate reduced. - Abstract: New BWR containment designs are considering cavity flooding as an accident management strategy. Unlike the PWR, the BWR has many Control Rod Guide Tube (CRGT) penetrations in the lower head. During a severe accident scenario with core melt in the lower plenum along with cavity flooding, the penetrations may affect the heat transfer on the ex-vessel surface and disrupt fluid flow during the boiling process. A small-scale experiment was performed to investigate the issues existing in downward-facing boiling phenomenon with an extended surface. The results were compared with a bare (flat) surface. The mass flux of 244 kg/m{sup 2} s, 215 kg/m{sup 2} s, and 177 kg/m{sup 2} s were applied in this study. CHF conditions were observed only for the 177 kg/m{sup 2} s case. The boiling curves for both types of surfaces and all flow rates were obtained. The boiling curves for the highest flow rate showed lower surface temperatures for the extended surface experiments when compared to the bare surface. The downstream location on the extended surface yielded the highest surface temperatures as the flow rate was reduced. The bubble accumulation and low velocity in the wake produced by flow around the extended surface was believed to have caused the elevated temperatures in the downstream location. Although an extended surface may enhance the overall heat transfer, a reduction in the local heat transfer was observed in the current experiments.

  1. Study of natural energy system and downward atmospheric radiation. Part 2. Study of downward atmospheric radiation simple estimated formula and elective longwave radiation; Shizen energy system to tenku hosharyo no kansoku kenkyu. 2. Tenku hosharyo kan`i suiteishiki to jikko hosharyo no kento

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, K; Yano, S [Kogakuin University, Tokyo (Japan); Masuoka, Y

    1997-11-25

    With an objective to design and control a natural energy utilization system, this paper describes discussions on a simple estimation formula for downward atmospheric radiation. The simple estimation formula for downward atmospheric radiation using a square root of steam partial pressure, {sigma}T{sup 4} ({sigma} is the Stefan Boltzmann constant, and T is the absolute outside air temperature), and SAT (observation value for corresponding outside air temperature) as explanatory variables was added with data made available further to improve its accuracy. A calculated value, whose formula had observation values at each location substituted, had coefficient of correlation with the observation values of 0.9. This formula was found applicable to each location. The effective radiation amount is the difference between the downward atmospheric radiation and the long wavelength radiation from the ground surface, from which a formula to simply estimate the effective radiation was proposed. Although there is a slight difference, the calculated values derived by using this formula agreed nearly well with the observation values of the effective radiation. A standard SAT meter was used to discuss cooling effect of atmospheric radiation cooling on the ground surface, whereas the cooling effect was verified to appear markedly under windless condition at night. It was found that the cooling effect is more remarkable in winter than in summer. 14 refs., 8 figs., 1 tab.

  2. Bias correction of surface downwelling longwave and shortwave radiation for the EWEMBI dataset

    Science.gov (United States)

    Lange, Stefan

    2018-05-01

    Many meteorological forcing datasets include bias-corrected surface downwelling longwave and shortwave radiation (rlds and rsds). Methods used for such bias corrections range from multi-year monthly mean value scaling to quantile mapping at the daily timescale. An additional downscaling is necessary if the data to be corrected have a higher spatial resolution than the observational data used to determine the biases. This was the case when EartH2Observe (E2OBS; Calton et al., 2016) rlds and rsds were bias-corrected using more coarsely resolved Surface Radiation Budget (SRB; Stackhouse Jr. et al., 2011) data for the production of the meteorological forcing dataset EWEMBI (Lange, 2016). This article systematically compares various parametric quantile mapping methods designed specifically for this purpose, including those used for the production of EWEMBI rlds and rsds. The methods vary in the timescale at which they operate, in their way of accounting for physical upper radiation limits, and in their approach to bridging the spatial resolution gap between E2OBS and SRB. It is shown how temporal and spatial variability deflation related to bilinear interpolation and other deterministic downscaling approaches can be overcome by downscaling the target statistics of quantile mapping from the SRB to the E2OBS grid such that the sub-SRB-grid-scale spatial variability present in the original E2OBS data is retained. Cross validations at the daily and monthly timescales reveal that it is worthwhile to take empirical estimates of physical upper limits into account when adjusting either radiation component and that, overall, bias correction at the daily timescale is more effective than bias correction at the monthly timescale if sampling errors are taken into account.

  3. Estimating surface longwave radiative fluxes from satellites utilizing artificial neural networks

    Science.gov (United States)

    Nussbaumer, Eric A.; Pinker, Rachel T.

    2012-04-01

    A novel approach for calculating downwelling surface longwave (DSLW) radiation under all sky conditions is presented. The DSLW model (hereafter, DSLW/UMD v2) similarly to its predecessor, DSLW/UMD v1, is driven with a combination of Moderate Resolution Imaging Spectroradiometer (MODIS) level-3 cloud parameters and information from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim model. To compute the clear sky component of DSLW a two layer feed-forward artificial neural network with sigmoid hidden neurons and linear output neurons is implemented; it is trained with simulations derived from runs of the Rapid Radiative Transfer Model (RRTM). When computing the cloud contribution to DSLW, the cloud base temperature is estimated by using an independent artificial neural network approach of similar architecture as previously mentioned, and parameterizations. The cloud base temperature neural network is trained using spatially and temporally co-located MODIS and CloudSat Cloud Profiling Radar (CPR) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations. Daily average estimates of DSLW from 2003 to 2009 are compared against ground measurements from the Baseline Surface Radiation Network (BSRN) giving an overall correlation coefficient of 0.98, root mean square error (rmse) of 15.84 W m-2, and a bias of -0.39 W m-2. This is an improvement over an earlier version of the model (DSLW/UMD v1) which for the same time period has an overall correlation coefficient 0.97 rmse of 17.27 W m-2, and bias of 0.73 W m-2.

  4. Bias correction of surface downwelling longwave and shortwave radiation for the EWEMBI dataset

    Directory of Open Access Journals (Sweden)

    S. Lange

    2018-05-01

    Full Text Available Many meteorological forcing datasets include bias-corrected surface downwelling longwave and shortwave radiation (rlds and rsds. Methods used for such bias corrections range from multi-year monthly mean value scaling to quantile mapping at the daily timescale. An additional downscaling is necessary if the data to be corrected have a higher spatial resolution than the observational data used to determine the biases. This was the case when EartH2Observe (E2OBS; Calton et al., 2016 rlds and rsds were bias-corrected using more coarsely resolved Surface Radiation Budget (SRB; Stackhouse Jr. et al., 2011 data for the production of the meteorological forcing dataset EWEMBI (Lange, 2016. This article systematically compares various parametric quantile mapping methods designed specifically for this purpose, including those used for the production of EWEMBI rlds and rsds. The methods vary in the timescale at which they operate, in their way of accounting for physical upper radiation limits, and in their approach to bridging the spatial resolution gap between E2OBS and SRB. It is shown how temporal and spatial variability deflation related to bilinear interpolation and other deterministic downscaling approaches can be overcome by downscaling the target statistics of quantile mapping from the SRB to the E2OBS grid such that the sub-SRB-grid-scale spatial variability present in the original E2OBS data is retained. Cross validations at the daily and monthly timescales reveal that it is worthwhile to take empirical estimates of physical upper limits into account when adjusting either radiation component and that, overall, bias correction at the daily timescale is more effective than bias correction at the monthly timescale if sampling errors are taken into account.

  5. Downwelling Longwave Fluxes at Continental Surfaces-A Comparison of Observations with GCM Simulations and Implications for the Global Land-Surface Radiation Budget.

    Science.gov (United States)

    Garratt, J. R.; Prata, A. J.

    1996-03-01

    Previous work suggests that general circulation (global climate) models have excess net radiation at land surfaces, apparently due to overestimates in downwelling shortwave flux and underestimates in upwelling long-wave flux. Part of this excess, however, may be compensated for by an underestimate in downwelling longwave flux. Long term observations of the downwelling longwave component at several land stations in Europe, the United States, Australia, and Antarctica suggest that climate models (four are used, as in previous studies) underestimate this flux component on an annual basis by up to 10 W m2, yet with low statistical significance. It is probable that the known underestimate in boundary-layer air temperature contributes to this, as would low model cloudiness and neglect of minor gases such as methane, nitrogen oxide, and the freons. The bias in downwelling longwave flux, together with those found earlier for downwelling shortwave and upwlling long-wave fluxes, are consistent with the model bias found previously for net radiation. All annually averaged fluxes and biases are deduced for global land as a whole.

  6. Critical heat flux (CHF) phenomenon on a downward facing curved surface

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, F.B.; Haddad, K.H.; Liu, Y.C. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical Engineering

    1997-06-01

    This report describes a theoretical and experimental study of the boundary layer boiling and critical heat flux phenomena on a downward facing curved heating surface, including both hemispherical and toroidal surfaces. A subscale boundary layer boiling (SBLB) test facility was developed to measure the spatial variation of the critical heat flux and observe the underlying mechanisms. Transient quenching and steady-state boiling experiments were performed in the SBLB facility under both saturated and subcooled conditions to obtain a complete database on the critical heat flux. To complement the experimental effort, an advanced hydrodynamic CHF model was developed from the conservation laws along with sound physical arguments. The model provides a clear physical explanation for the spatial variation of the CHF observed in the SBLB experiments and for the weak dependence of the CHF data on the physical size of the vessel. Based upon the CHF model, a scaling law was established for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water. The scaling law, which compares favorably with all the available local CHF data obtained for various vessel sizes, can be used to predict the local CHF limits on large commercial-size vessels. This technical information represents one of the essential elements that is needed in assessing the efficacy of external cooling of core melt by cavity flooding as a severe accident management strategy. 83 figs., 3 tabs.

  7. Critical heat flux (CHF) phenomenon on a downward facing curved surface

    International Nuclear Information System (INIS)

    Cheung, F.B.; Haddad, K.H.; Liu, Y.C.

    1997-06-01

    This report describes a theoretical and experimental study of the boundary layer boiling and critical heat flux phenomena on a downward facing curved heating surface, including both hemispherical and toroidal surfaces. A subscale boundary layer boiling (SBLB) test facility was developed to measure the spatial variation of the critical heat flux and observe the underlying mechanisms. Transient quenching and steady-state boiling experiments were performed in the SBLB facility under both saturated and subcooled conditions to obtain a complete database on the critical heat flux. To complement the experimental effort, an advanced hydrodynamic CHF model was developed from the conservation laws along with sound physical arguments. The model provides a clear physical explanation for the spatial variation of the CHF observed in the SBLB experiments and for the weak dependence of the CHF data on the physical size of the vessel. Based upon the CHF model, a scaling law was established for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water. The scaling law, which compares favorably with all the available local CHF data obtained for various vessel sizes, can be used to predict the local CHF limits on large commercial-size vessels. This technical information represents one of the essential elements that is needed in assessing the efficacy of external cooling of core melt by cavity flooding as a severe accident management strategy. 83 figs., 3 tabs

  8. Critical heat flux for downward-facing pool boiling on CANDU calandria tube surface

    Energy Technology Data Exchange (ETDEWEB)

    Behdadi, Azin, E-mail: behdada@mcmaster.ca; Talebi, Farshad; Luxat, John

    2017-04-15

    Highlights: • Pressure tube-calandria tube contact may challenge fuel channel integrity in CANDU. • Critical heat flux variation is predicted on the outer surface of CANDU calandria tube. • A two-phase boundary layer flow driven by buoyancy is modeled on the surface. • Different slip ratios and flow regimes are considered inside the boundary layer. • Subcooling effects are added to the model using wall heat flux partitioning. - Abstract: One accident scenario in CANDU reactors that can challenge the integrity of the primary pressure boundary is a loss of coolant accident, referred to as critical break LOCA, in which the pressure tube (PT) can undergo thermal creep strain deformation and contact its calandria tube (CT). In such case, rapid redistribution of stored heat from PT to CT, leads to a large spike in heat flux to the moderator which can cause bubble accumulation and dryout on the CT surface. A challenge to fuel channel integrity is posed if critical heat flux occurs on the surface of the CT and results in sustained film boiling. If the post-dryout temperature becomes sufficiently high then continued creep strain of the PT and CT may lead to fuel channel failure. In this study, a mechanistic model is developed to predict the critical heat flux variations along the downward facing outer surface of CT. The hydrodynamic model considers a liquid macrolayer beneath an elongated vapor slug on the surface. Local dryout is postulated to occur whenever the fresh liquid supply to the macrolayer is not sufficient to compensate for the liquid depletion. A boundary layer analysis is performed, treating the two phase motion as an external buoyancy driven flow. The model shows good agreement with the available experimental data and has been modified to take into account the effect of subcooling.

  9. Experimental and theoretical study on transition boiling concerning downward-facing horizontal surface in confined space

    International Nuclear Information System (INIS)

    Zhao, D.W.; Su, G.H.; Tian, W.X.; Sugiyama, K.; Qiu, S.Z.

    2008-01-01

    Experimental study has been conducted to examine the pool boiling occurs on a relative large downward-facing round surface with a diameter of 300 mm in confined water pool at atmospheric pressure. An artificial neural network (ANN) has been trained successfully based on the experimental data for predicting Nusselt number of transition boiling in the present study. The input parameters of the ANN are wall superheat, ΔT w , the ratio of the gap size to the diameter of the heated surface, δ/D, Prandtl number and Rayleigh number. The output is Nusselt number, Nu. The results show that: Nu decreases with increasing ΔT w , and increases generally with an increase of δ/D. Nu increases with increasing Pr when gap size is smaller than 4.0 mm. And Nu decreases initially and then increases with increasing Pr as gap size bigger than 5.0 mm. The results also indicate that the influence of Grashof number, Gr, could be negligible. Finally, a new correlation was proposed to predict the transition boiling heat transfer under the present condition. The comparisons between the prediction of the new correlation and experimental data show a reasonable agreement

  10. Comparison of several databases of downward solar daily irradiation data at ocean surface with PIRATA measurements

    Science.gov (United States)

    Trolliet, Mélodie; Wald, Lucien

    2017-04-01

    The solar radiation impinging at sea surface is an essential variable in climate system. There are several means to assess the daily irradiation at surface, such as pyranometers aboard ship or on buoys, meteorological re-analyses and satellite-derived databases. Among the latter, assessments made from the series of geostationary Meteosat satellites offer synoptic views of the tropical and equatorial Atlantic Ocean every 15 min with a spatial resolution of approximately 5 km. Such Meteosat-derived databases are fairly recent and the quality of the estimates of the daily irradiation must be established. Efforts have been made for the land masses and must be repeated for the Atlantic Ocean. The Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) network of moorings in the Tropical Atlantic Ocean is considered as a reference for oceanographic data. It consists in 17 long-term Autonomous Temperature Line Acquisition System (ATLAS) buoys equipped with sensors to measure near-surface meteorological and subsurface oceanic parameters, including downward solar irradiation. Corrected downward solar daily irradiation from PIRATA were downloaded from the NOAA web site and were compared to several databases: CAMS RAD, HelioClim-1, HelioClim-3 v4 and HelioClim-3 v5. CAMS-RAD, the CAMS radiation service, combines products of the Copernicus Atmosphere Monitoring Service (CAMS) on gaseous content and aerosols in the atmosphere together with cloud optical properties deduced every 15 min from Meteosat imagery to supply estimates of the solar irradiation. Part of this service is the McClear clear sky model that provides estimates of the solar irradiation that should be observed in cloud-free conditions. The second and third databases are HelioClim-1 and HelioClim-3 v4 that are derived from Meteosat images using the Heliosat-2 method and the ESRA clear sky model, based on the Linke turbidity factor. HelioClim-3 v5 is the fourth database and differs from v4 by the

  11. Studies on boiling heat transfer on a hemispherical downward heating surface supposing IVR-AM

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Matsumoto, Hiroyuki; Matsumoto, Tadayoshi; Kataoka, Isao

    2006-01-01

    The scale-down experiments supposing the IVR-AM were made on the pool boiling heat transfer from hemispherical downward facing heating surface. The boiling phenomena were realized by flooding the heated hemispherical vessel into the sub-cooled water or saturated water under the atmospheric pressure. The hemispherical vessel supposing the scale-down pressure vessel was made of SUS304 stainless steel. Molten lead, which was preheated up to about 500 degrees Celsius, was put into the vessel and used as the heat source. The vessel was cooled down by flooding into the water to realize the quenching process. The direct observation by using the digital video camera was performed and made clear the special characteristics of boiling phenomena such as the film boiling, the transition boiling and the nucleate boiling taking place in order during the cooling process. The measurement for the wall superheat and heat flux by using thermocouples was also carried out to make clear the boiling heat transfer characteristics during the cooling process. Fifteen thermocouples are inserted in the wall of the hemispherical bowl to measure the temperature distributions and heat flux in the hemispherical bowl. (author)

  12. Estimation of sea surface salinity in the Bay of Bengal using Outgoing Longwave Radiation

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Subrahmanyam, B.; Sarma, M.S.S.; Tilvi, V.; RameshBabu, V.

    .5C176 C2 2.5C176 grids in conjunction with the OLR maps. 3. Results and Discussion [7] Figures 1a–1c show the distributions of climatolog- ical OLR (CDC, USA), E-P (SOCC, UK) and SSS (WOA98) data sets for June in the tropical Indian Ocean and western...) (Figure 2c) and in the northern Andaman Sea during northern fall (October) (Figure 2d). Since the temperature in the stratified layer Figure 1. Distributions of (a) Outgoing Longwave Radia- tion (CDC, USA), (b) Evaporation minus Precipitation (SOCC, UK...

  13. Estimating Surface Downward Shortwave Radiation over China Based on the Gradient Boosting Decision Tree Method

    Directory of Open Access Journals (Sweden)

    Lu Yang

    2018-01-01

    Full Text Available Downward shortwave radiation (DSR is an essential parameter in the terrestrial radiation budget and a necessary input for models of land-surface processes. Although several radiation products using satellite observations have been released, coarse spatial resolution and low accuracy limited their application. It is important to develop robust and accurate retrieval methods with higher spatial resolution. Machine learning methods may be powerful candidates for estimating the DSR from remotely sensed data because of their ability to perform adaptive, nonlinear data fitting. In this study, the gradient boosting regression tree (GBRT was employed to retrieve DSR measurements with the ground observation data in China collected from the China Meteorological Administration (CMA Meteorological Information Center and the satellite observations from the Advanced Very High Resolution Radiometer (AVHRR at a spatial resolution of 5 km. The validation results of the DSR estimates based on the GBRT method in China at a daily time scale for clear sky conditions show an R2 value of 0.82 and a root mean square error (RMSE value of 27.71 W·m−2 (38.38%. These values are 0.64 and 42.97 W·m−2 (34.57%, respectively, for cloudy sky conditions. The monthly DSR estimates were also evaluated using ground measurements. The monthly DSR estimates have an overall R2 value of 0.92 and an RMSE of 15.40 W·m−2 (12.93%. Comparison of the DSR estimates with the reanalyzed and retrieved DSR measurements from satellite observations showed that the estimated DSR is reasonably accurate but has a higher spatial resolution. Moreover, the proposed GBRT method has good scalability and is easy to apply to other parameter inversion problems by changing the parameters and training data.

  14. The potential influence of multiple scattering on longwave flux and heating rate simulations with clouds

    Science.gov (United States)

    Kuo, C. P.; Yang, P.; Huang, X.; Feldman, D.; Flanner, M.; Kuo, C.; Mlawer, E. J.

    2017-12-01

    Clouds, which cover approximately 67% of the globe, serve as one of the major modulators in adjusting radiative energy on the Earth. Since rigorous radiative transfer computations including multiple scattering are costly, only absorption is considered in the longwave spectral bands in the radiation sub-models of the general circulation models (GCMs). Quantification of the effect of ignoring longwave scattering for flux and heating rate simulations is performed by using the GCM version of the Longwave Rapid Radiative Transfer Model (RRTMG_LW) with an implementation with the 16-stream Discrete Ordinates Radiative Transfer (DISORT) Program for a Multi-Layered Plane-Parallel Medium in conjunction with the 2010 CCCM products that merge satellite observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), the CloudSat, the Clouds and the Earth's Radiant Energy System (CERES) and the Moderate Resolution Imaging Spectrometer (MODIS). One-year global simulations show that neglecting longwave scattering overestimates upward flux at the top of the atmosphere (TOA) and underestimates downward flux at the surface by approximately 2.63 and 1.15 W/m2, respectively. Furthermore, when longwave scattering is included in the simulations, the tropopause is cooled by approximately 0.018 K/day and the surface is heated by approximately 0.028 K/day. As a result, the radiative effects of ignoring longwave scattering and doubling CO2 are comparable in magnitude.

  15. A study on the upward and downward facing pool boiling heat transfer characteristics of graphene-modified surface

    International Nuclear Information System (INIS)

    Kim, Ji Hoon; Ahn, Ho Seon; Kim, Ji Min

    2016-01-01

    Recently, graphene, carbon in two dimensions, were highlighted as a good heat transfer materials, according to its high thermal conductivity. Lateral conduction and water absorption into the structure helped graphene films to inhibit the formation of hot spots, which means increasing of critical heat flux (CHF) and boiling heat transfer coefficient (BHTC) performances. In this study, we report a promising increase of CHF and BHTC results with 2D graphene films. Furthermore, we tried to observe bubble behavior via high-speed visualization to investigate a relationship between bubble behavior and pool boiling performances in downward facing boiling. The effect of graphene film coating on the pool boiling performances of upward and downward facing heater surface were examined. 2D- and 3D- graphene film showed good enhancement results on the CHF (by 111% and 60%) and BHTC (by 40% and 20-25%) performances. Bubble behavior change was significant factor on the CHF and BHTC performances in downward facing boiling. The amount of evaporation heat flux was calculated from the velocity, bubble diameter, frequency, orientation angle and superheat that the post-products of the high-speed visualization

  16. Temporal Arctic longwave surface emissivity feedbacks in the Community Earth System Model

    Science.gov (United States)

    Kuo, C.; Feldman, D.; Huang, X.; Flanner, M.; Yang, P.; Chen, X.

    2017-12-01

    We have investigated how the inclusion of realistic and consistent surface emissivity in both land-surface and atmospheric components of the CESM coupled-climate model affects a wide range of climate variables. We did this by replacing the unit emissivity values in RRTMG_LW for water, fine-grained snow, and desert scenes with spectral emissivity values, and by replacing broadband emissivity values in surface components with the Planck-curve weighted counterparts. We find that this harmonized treatment of surface emissivity within CESM can be important for reducing high-latitude temperature biases. We also find that short-term effects of atmospheric dynamics and spectral information need to be considered to understand radiative effects in higher detail, and are possible with radiative kernels computed for every grid and time point for the entire model integration period. We find that conventional climatological feedback calculations indicate that sea-ice emissivity feedback is positive in sign, but that the radiative effects of the difference in emissivity between frozen and unfrozen surfaces exhibit seasonal dependence. Furthermore, this seasonality itself exhibits meridional asymmetry due to differences in sea-ice response to climate forcing between the Arctic and the Antarctic. In the Arctic, this seasonal, temporally higher order analysis exhibits increasing outgoing surface emissivity radiative response in a warming climate. While the sea-ice emissivity feedback and seasonal sea-ice emissivity radiative response amplitudes are a few percent of surface albedo feedbacks, the feedback analysis methods outlined in this work demonstrate that spatially and temporally localized feedback analysis can give insight into the mechanisms at work on those scales which differ in amplitude and sign from conventional climatological analyses. We note that the inclusion of this realistic physics leads to improved agreement between CESM model results and Arctic surface

  17. Spatial Representativeness of Surface-Measured Variations of Downward Solar Radiation

    Science.gov (United States)

    Schwarz, M.; Folini, D.; Hakuba, M. Z.; Wild, M.

    2017-12-01

    When using time series of ground-based surface solar radiation (SSR) measurements in combination with gridded data, the spatial and temporal representativeness of the point observations must be considered. We use SSR data from surface observations and high-resolution (0.05°) satellite-derived data to infer the spatiotemporal representativeness of observations for monthly and longer time scales in Europe. The correlation analysis shows that the squared correlation coefficients (R2) between SSR times series decrease linearly with increasing distance between the surface observations. For deseasonalized monthly mean time series, R2 ranges from 0.85 for distances up to 25 km between the stations to 0.25 at distances of 500 km. A decorrelation length (i.e., the e-folding distance of R2) on the order of 400 km (with spread of 100-600 km) was found. R2 from correlations between point observations and colocated grid box area means determined from satellite data were found to be 0.80 for a 1° grid. To quantify the error which arises when using a point observation as a surrogate for the area mean SSR of larger surroundings, we calculated a spatial sampling error (SSE) for a 1° grid of 8 (3) W/m2 for monthly (annual) time series. The SSE based on a 1° grid, therefore, is of the same magnitude as the measurement uncertainty. The analysis generally reveals that monthly mean (or longer temporally aggregated) point observations of SSR capture the larger-scale variability well. This finding shows that comparing time series of SSR measurements with gridded data is feasible for those time scales.

  18. Steady-state subcooled nucleate boiling on a downward facing hemispherical surface

    International Nuclear Information System (INIS)

    Haddad, K.H.; Cheung, F.B.

    1996-01-01

    Steady-state nucleate boiling heat transfer experiments in saturated and subcooled water were conducted. The heating surface was a 0.305 m hemispherical aluminum vessel heated from the inside with water boiling on the outside. It was found that subcooling had very little effect on the nucleate boiling curve in the high heat flux regime where latent heat transport dominated. On the other hand, a relatively large effect of subcooling was observed in the low heat flux regime where sensible heat transport was important. Photographic records of the boiling phenomenon and the bubble dynamics indicated that in the high heat flux regime, boiling in the bottom center region of the vessel was cyclic in nature with a liquid heating phase, a bubble nucleation and growth phase, a bubble coalescence phase, and a large vapor mass ejection phase. At the same heat flux level, the size of the vapor masses was found to decrease from the bottom center toward the upper edge of the vessel, which was consistent with the observed increase in the critical heat flux in the flow direction along the curved heating surface

  19. Effect of subcooling and wall thickness on pool boiling from downward-facing curved surfaces in water

    Energy Technology Data Exchange (ETDEWEB)

    El-Genk, M.S.; Glebov, A.G. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-09-01

    Quenching experiments were performed to investigate the effects of water subcooling and wall thickness on pool boiling from a downward-facing curved surface. Experiments used three copper sections of the same diameter (50.8 mm) and surface radius (148 mm), but different thickness (12.8, 20 and 30 mm). Local and average pool boiling curves were obtained at saturation and 5 K, 10 K, and 14 K subcooling. Water subcooling increased the maximum heat flux, but decreased the corresponding wall superheat. The minimum film boiling heat flux and the corresponding wall superheat, however, increased with increased subcooling. The maximum and minimum film boiling heat fluxes were independent of wall thickness above 20 mm and Biot Number > 0.8, indicating that boiling curves for the 20 and 30 thick sections were representative of quasi steady-state, but not those for the 12.8 mm thick section. When compared with that for a flat surface section of the same thickness, the data for the 12.8 mm thick section showed significant increases in both the maximum heat flux (from 0.21 to 0.41 MW/m{sup 2}) and the minimum film boiling heat flux (from 2 to 13 kW/m{sup 2}) and about 11.5 K and 60 K increase in the corresponding wall superheats, respectively.

  20. Variability and trends of downward surface global solar radiation over the Iberian Peninsula based on ERA-40 reanalysis

    KAUST Repository

    Perdigão, João Carlos

    2016-01-26

    © 2016 Royal Meteorological Society. A climate study of the incidence of downward surface global solar radiation (SSRD) in the Iberian Peninsula (IP) based primarily on ERA-40 reanalysis is presented. NCEP/NCAR reanalysis and ground-based records from several Portuguese and Spanish stations have been also considered. The results show that reanalysis can capture a similar inter-annual variability as compared to ground-based observations, especially on a monthly basis, even though annual ERA-40 (NCEP/NCAR) values tend to underestimate (overestimate) the observations with a mean relative difference of around 20Wm-2 (40Wm-2). On the other hand, ground-based measurements in Portuguese stations during the period 1964-1989 show a tendency to decrease until the mid-1970s followed by an increase up to the end of the study period, in line with the dimming/brightening phenomenon reported in the literature. Nevertheless, there are different temporal behaviours as a greater increase since the 1970s is observed in the south and less industrialized regions. Similarly, the ERA-40 reanalysis shows a noticeable decrease until the early 1970s followed by a slight increase up to the end of the 1990s, suggesting a dimming/brightening transition around the early 1970s, earlier in the south and centre and later in the north of the IP. Although there are slight differences in the magnitude of the trends as well as the turning year of the dimming/brightening periods, the decadal changes of ERA-40 fairly agree with the ground-based observations in Portugal and Spain, in contrast to most of the literature for other regions of the world, and is used in the climatology of the SSRD in the study area. NCEP/NCAR reanalysis does not capture the decadal variations of SSRD in the IP. The results show that part of the decadal variability of the global radiation in the IP is related to changes in cloud cover (represented in ERA-40).

  1. Variability and trends of downward surface global solar radiation over the Iberian Peninsula based on ERA-40 reanalysis

    KAUST Repository

    Perdigã o, Joã o Carlos; Salgado, Rui; Costa, Maria Joã o; Dasari, Hari Prasad; Sanchez-Lorenzo, Arturo

    2016-01-01

    © 2016 Royal Meteorological Society. A climate study of the incidence of downward surface global solar radiation (SSRD) in the Iberian Peninsula (IP) based primarily on ERA-40 reanalysis is presented. NCEP/NCAR reanalysis and ground-based records from several Portuguese and Spanish stations have been also considered. The results show that reanalysis can capture a similar inter-annual variability as compared to ground-based observations, especially on a monthly basis, even though annual ERA-40 (NCEP/NCAR) values tend to underestimate (overestimate) the observations with a mean relative difference of around 20Wm-2 (40Wm-2). On the other hand, ground-based measurements in Portuguese stations during the period 1964-1989 show a tendency to decrease until the mid-1970s followed by an increase up to the end of the study period, in line with the dimming/brightening phenomenon reported in the literature. Nevertheless, there are different temporal behaviours as a greater increase since the 1970s is observed in the south and less industrialized regions. Similarly, the ERA-40 reanalysis shows a noticeable decrease until the early 1970s followed by a slight increase up to the end of the 1990s, suggesting a dimming/brightening transition around the early 1970s, earlier in the south and centre and later in the north of the IP. Although there are slight differences in the magnitude of the trends as well as the turning year of the dimming/brightening periods, the decadal changes of ERA-40 fairly agree with the ground-based observations in Portugal and Spain, in contrast to most of the literature for other regions of the world, and is used in the climatology of the SSRD in the study area. NCEP/NCAR reanalysis does not capture the decadal variations of SSRD in the IP. The results show that part of the decadal variability of the global radiation in the IP is related to changes in cloud cover (represented in ERA-40).

  2. Net radiation of mountain cultivated Norway spruce [Picea abies (L.) Karst.] stand: evaluation of shortand long-wave radiation ratio

    Czech Academy of Sciences Publication Activity Database

    Marková, I.; Marek, Michal V.

    2011-01-01

    Roč. 53, č. 2 (2011), s. 114-122 ISSN 0071-6677 Institutional research plan: CEZ:AV0Z60870520 Keywords : downward short- and long-wave radiation * upward short- and long-wave radiation * sun elevation * clearness index Subject RIV: GK - Forestry

  3. Single bubble dynamic behavior in AL{sub 2}O{sub 3}/H{sub 2}O nanofluid on downward-facing heating surface

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Wu, Junmei [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an (China)

    2016-08-15

    After a severe accident to the nuclear reactor, the in-vessel retention strategy is a key way to prevent the leakage of radioactive material. Nanofluid is a steady suspension used to improve heat-transfer characteristics of working fluids, formed by adding solid particles with diameters below 100 nm to the base fluids, and its thermal physical properties and heat-transfer characteristics are much different from the conventional working fluids. Thus, nanofluids with appropriate nanoparticle type and volume concentration can enhance the heat-transfer process. In this study, the moving particle semi-implicit method-meshless advection using flow-directional local grid method is used to simulate the bubble growth, departure, and sliding on the downward-facing heating surface in pure water and nanofluid (1.0 vol.% Al2O3/H2O) flow boiling processes; additionally, the bubble critical departure angle and sliding characteristics and their influence are also investigated. The results indicate that the bubble in nanofluid departs from the heating surface more easily and the critical departure inclined angle of nanofluid is greater than that of pure water. In addition, the influence of nanofluid on bubble sliding is not significant compared with pure water.

  4. Improvements of top-of-atmosphere and surface irradiance computations with CALIPSO-, CloudSat-, and MODIS-derived cloud and aerosol properties

    Science.gov (United States)

    Kato, Seiji; Rose, Fred G.; Sun-Mack, Sunny; Miller, Walter F.; Chen, Yan; Rutan, David A.; Stephens, Graeme L.; Loeb, Norman G.; Minnis, Patrick; Wielicki, Bruce A.; Winker, David M.; Charlock, Thomas P.; Stackhouse, Paul W., Jr.; Xu, Kuan-Man; Collins, William D.

    2011-10-01

    One year of instantaneous top-of-atmosphere (TOA) and surface shortwave and longwave irradiances are computed using cloud and aerosol properties derived from instruments on the A-Train Constellation: the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, the CloudSat Cloud Profiling Radar (CPR), and the Aqua Moderate Resolution Imaging Spectrometer (MODIS). When modeled irradiances are compared with those computed with cloud properties derived from MODIS radiances by a Clouds and the Earth's Radiant Energy System (CERES) cloud algorithm, the global and annual mean of modeled instantaneous TOA irradiances decreases by 12.5 W m-2 (5.0%) for reflected shortwave and 2.5 W m-2 (1.1%) for longwave irradiances. As a result, the global annual mean of instantaneous TOA irradiances agrees better with CERES-derived irradiances to within 0.5W m-2 (out of 237.8 W m-2) for reflected shortwave and 2.6W m-2 (out of 240.1 W m-2) for longwave irradiances. In addition, the global annual mean of instantaneous surface downward longwave irradiances increases by 3.6 W m-2 (1.0%) when CALIOP- and CPR-derived cloud properties are used. The global annual mean of instantaneous surface downward shortwave irradiances also increases by 8.6 W m-2 (1.6%), indicating that the net surface irradiance increases when CALIOP- and CPR-derived cloud properties are used. Increasing the surface downward longwave irradiance is caused by larger cloud fractions (the global annual mean by 0.11, 0.04 excluding clouds with optical thickness less than 0.3) and lower cloud base heights (the global annual mean by 1.6 km). The increase of the surface downward longwave irradiance in the Arctic exceeds 10 W m-2 (˜4%) in winter because CALIOP and CPR detect more clouds in comparison with the cloud detection by the CERES cloud algorithm during polar night. The global annual mean surface downward longwave irradiance of

  5. A study of longwave radiation codes for climate studies: Validation with ARM observations and tests in general circulation models

    International Nuclear Information System (INIS)

    Ellingson, R.G.; Baer, F.

    1993-01-01

    This report summarizes the activities of our group to meet our stated objectives. The report is divided into sections entitled: Radiation Model Testing Activities, General Circulation Model Testing Activities, Science Team Activities, and Publications, Presentations and Meetings. The section on Science Team Activities summarizes our participation with the science team to further advance the observation and modeling programs. Appendix A lists graduate students supported, and post-doctoral appointments during the project. Reports on the activities during each of the first two years are included as Appendix B. Significant progress has been made in: determining the ability of line-by-line radiation models to calculate the downward longwave flux at the surface; determining the uncertainties in calculated the downwelling radiance and flux at the surface associated with the use of different proposed profiling techniques; intercomparing clear-sky radiance and flux observations with calculations from radiation codes from different climate models; determining the uncertainties associated with estimating N* from surface longwave flux observations; and determining the sensitivity of model calculations to different formulations of the effects of finite sized clouds

  6. The influence of Cloud Longwave Scattering together with a state-of-the-art Ice Longwave Optical Parameterization in Climate Model Simulations

    Science.gov (United States)

    Chen, Y. H.; Kuo, C. P.; Huang, X.; Yang, P.

    2017-12-01

    Clouds play an important role in the Earth's radiation budget, and thus realistic and comprehensive treatments of cloud optical properties and cloud-sky radiative transfer are crucial for simulating weather and climate. However, most GCMs neglect LW scattering effects by clouds and tend to use inconsistent cloud SW and LW optical parameterizations. Recently, co-authors of this study have developed a new LW optical properties parameterization for ice clouds, which is based on ice cloud particle statistics from MODIS measurements and state-of-the-art scattering calculation. A two-stream multiple-scattering scheme has also been implemented into the RRTMG_LW, a widely used longwave radiation scheme by climate modeling centers. This study is to integrate both the new LW cloud-radiation scheme for ice clouds and the modified RRTMG_LW with scattering capability into the NCAR CESM to improve the cloud longwave radiation treatment. A number of single column model (SCM) simulations using the observation from the ARM SGP site on July 18 to August 4 in 1995 are carried out to assess the impact of new LW optical properties of clouds and scattering-enabled radiation scheme on simulated radiation budget and cloud radiative effect (CRE). The SCM simulation allows interaction between cloud and radiation schemes with other parameterizations, but the large-scale forcing is prescribed or nudged. Comparing to the results from the SCM of the standard CESM, the new ice cloud optical properties alone leads to an increase of LW CRE by 26.85 W m-2 in average, as well as an increase of the downward LW flux at surface by 6.48 W m-2. Enabling LW cloud scattering further increases the LW CRE by another 3.57 W m-2 and the downward LW flux at the surface by 0.2 W m-2. The change of LW CRE is mainly due to an increase of cloud top height, which enhances the LW CRE. A long-term simulation of CESM will be carried out to further understand the impact of such changes on simulated climates.

  7. Atmospheric transport, clouds and the Arctic longwave radiation paradox

    Science.gov (United States)

    Sedlar, Joseph

    2016-04-01

    Clouds interact with radiation, causing variations in the amount of electromagnetic energy reaching the Earth's surface, or escaping the climate system to space. While globally clouds lead to an overall cooling radiative effect at the surface, over the Arctic, where annual cloud fractions are high, the surface cloud radiative effect generally results in a warming. The additional energy input from absorption and re-emission of longwave radiation by the clouds to the surface can have a profound effect on the sea ice state. Anomalous atmospheric transport of heat and moisture into the Arctic, promoting cloud formation and enhancing surface longwave radiation anomalies, has been identified as an important mechanism in preconditioning Arctic sea ice for melt. Longwave radiation is emitted equally in all directions, and changes in the atmospheric infrared emission temperature and emissivity associated with advection of heat and moisture over the Arctic should correspondingly lead to an anomalous signal in longwave radiation at the top of the atmosphere (TOA). To examine the role of atmospheric heat and moisture transport into the Arctic on TOA longwave radiation, infrared satellite sounder observations from AIRS during 2003-2014 are analyzed for summer (JJAS). Thermodynamic metrics are developed to identify months characterized by a high frequency of warm and moist advection into the Arctic, and segregate the 2003-14 time period into climatological and anomalously warm, moist summer months. We find that anomalously warm, moist months result in a significant TOA longwave radiative cooling, which is opposite the forcing signal that the surface experiences during these months. At the timescale of the advective events, 3-10 days, the TOA cooling can be as large as the net surface energy budget during summer. When averaged on the monthly time scale, and over the full Arctic basin (poleward of 75°N), summer months experiencing frequent warm, moist advection events are

  8. Incoming longwave radiation to melting snow: observations, sensitivity and estimation in Northern environments

    Science.gov (United States)

    Sicart, J. E.; Pomeroy, J. W.; Essery, R. L. H.; Bewley, D.

    2006-11-01

    At high latitudes, longwave radiation can provide similar, or higher, amounts of energy to snow than shortwave radiation due to the low solar elevation (cosine effect and increased scattering due to long atmospheric path lengths). This effect is magnified in mountains due to shading and longwave emissions from the complex topography. This study examines longwave irradiance at the snow surface in the Wolf Creek Research Basin, Yukon Territory, Canada (60° 36N, 134° 57W) during the springs of 2002 and 2004. Incoming longwave radiation was estimated from standard meteorological measurements by segregating radiation sources into clear sky, clouds and surrounding terrain. A sensitivity study was conducted to detect the atmospheric and topographic conditions under which emission from adjacent terrain significantly increases the longwave irradiance. The total incoming longwave radiation is more sensitive to sky view factor than to the temperature of the emitting terrain surfaces. Brutsaert's equation correctly simulates the clear-sky irradiance for hourly time steps using temperature and humidity. Longwave emissions from clouds, which raised longwave radiation above that from clear skies by 16% on average, were best estimated using daily atmospheric shortwave transmissivity and hourly relative humidity. An independent test of the estimation procedure for a prairie site near Saskatoon, Saskatchewan, Canada, indicated that the calculations are robust in late winter and spring conditions. Copyright

  9. Calibrated Mid-wave Infrared (IR) (MidIR) and Long-wave IR (LWIR) Stokes and Degree-of-Liner Polarization (DOLP)

    Science.gov (United States)

    2008-09-01

    radiance from natural surfaces, was recorded continuously using an Eppley long-wave pyranometer . The long-wave pyranometer is designed to measure radiance...meteorological parameters as well as the ambient radiant loading experienced during the test recorded by the Eppley long-wave pyranometer . Tables 1

  10. Downwelling radiation at the sea surface in the central Mediterranean: one year of shortwave and longwave irradiance measurements on the Lampedusa buoy

    Science.gov (United States)

    di Sarra, Alcide; Bommarito, Carlo; Anello, Fabrizio; Di Iorio, Tatiana; Meloni, Daniela; Monteleone, Francesco; Pace, Giandomenico; Piacentino, Salvatore; Sferlazzo, Damiano

    2017-04-01

    An oceanographic buoy has been developed and deployed in August 2015 about 3.3 miles South West of the island of Lampedusa, at 35.49°N, 12.47°E, in the central Mediterranean Sea. The buoy was developed within the Italian RITMARE flagship project, and contributes to the Italian fixed-point oceanographic observation network. The buoy is an elastic beacon type and is intended to study air-sea interactions, propagation of radiation underwater, and oceanographic properties. The buoy measurements complement the atmospheric observations carried out at the long-term Station for Climate Observations on the island of Lampedusa (www.lampedusa.enea.it; 35.52°N, 12.63°E), which is located about 15 km E-NE of the buoy. Underwater instruments and part of the atmospheric sensors are presently being installed on the buoy. Measurements of downwelling shortwave, SW, and longwave, LW, irradiance, have been made since September 2015 with a Kipp and Zonen CMP21 pyranometer and a Kipp and Zonen CGR4 pyrgeometer, respectively. The radiometers are mounted on a small platform at about 7 m above sea level, on an arm protruding southward of the buoy. High time resolution data, at 1 Hz, have been acquired since December 2015, together with the sensors' attitude. Data from the period December 2015-December 2016 are analyzed and compared with measurements made on land at the Station for Climate Observations at 50 m above mean sea level. This study aims at deriving high quality determinations of the downwelling radiation over sea in the central Mediterranean. The following aspects will be discussed: - representativeness of time averaging of irradiance measurements over moving platforms; - comparison of downwelling irradiance measurements made over land and over ocean, and identification of possible correction strategies to infer irradiances over the ocean from close by measurements made over land; - influence of dome cleaning on the quality of measurements; - envisaging possible corrections

  11. Longwave atmospheric radiation as a possible indicator of the aviation impact

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, N A [Central Aerological Observatory of the Russian Federal Service for Hydrometeorology and Environmental Monitoring, Moscow (Russian Federation)

    1998-12-31

    Aircraft emissions changing composition of the atmospheric air should be sensed by radiation parameters, such as downward (in first turn) and upward long-wave fluxes. It might be supposed that the accurate measurements of long-wave (LW) radiation fluxes in regions of crowded aircraft routes time outside these regions, could detect the influence. Main transformation of the long-wave radiation (LWR) proceeds in the troposphere which absorbs and irradiates the LWR. The only mass method of the LWR measurements in the free atmosphere became the radiometer probe. In the former USSR it was successfully developed in 1961, and since 1963 the special radiometer sounding network started to make regular observations over the USSR territory. Rather small spatial variations of the downward LWR flux was observed indicating rather high homogeneity of the atmosphere composition. Analysis of the seasonal variations of the downward LWR has revealed that over some stations it has the opposite course of changes from summer to winter and it is mainly observed at rather high levels. (R.P.) 10 refs.

  12. Longwave atmospheric radiation as a possible indicator of the aviation impact

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, N.A. [Central Aerological Observatory of the Russian Federal Service for Hydrometeorology and Environmental Monitoring, Moscow (Russian Federation)

    1997-12-31

    Aircraft emissions changing composition of the atmospheric air should be sensed by radiation parameters, such as downward (in first turn) and upward long-wave fluxes. It might be supposed that the accurate measurements of long-wave (LW) radiation fluxes in regions of crowded aircraft routes time outside these regions, could detect the influence. Main transformation of the long-wave radiation (LWR) proceeds in the troposphere which absorbs and irradiates the LWR. The only mass method of the LWR measurements in the free atmosphere became the radiometer probe. In the former USSR it was successfully developed in 1961, and since 1963 the special radiometer sounding network started to make regular observations over the USSR territory. Rather small spatial variations of the downward LWR flux was observed indicating rather high homogeneity of the atmosphere composition. Analysis of the seasonal variations of the downward LWR has revealed that over some stations it has the opposite course of changes from summer to winter and it is mainly observed at rather high levels. (R.P.) 10 refs.

  13. DETERMINANT OF DOWNWARD AUDITOR SWITCHING

    Directory of Open Access Journals (Sweden)

    Totok Budisantoso

    2017-12-01

    Full Text Available Abstract: Determinant of Downward Auditor Switching. This study examines the factors that influence downward auditor switching in five ASEAN countries. Fixed effect logistic regression was used as analytical method. This study found that opinion shopping occurred in ASEAN, especially in distress companies. Companies with complex businesses will retain the Big Four auditors to reduce complexity and audit costs. Audit and public committees serve as guardians of auditor quality. On the other hand, shareholders failed to maintain audit quality. It indicates that there is entrenchment effect in auditor switching.

  14. Downward surface flux computations in a vertically inhomogeneous grey planetary atmosphere Cálculo do fluxo radiativo superficial em uma atmosfera planetária cinza e verticalmente não-homogênea

    Directory of Open Access Journals (Sweden)

    Marcos Pimenta de Abreu

    2008-03-01

    Full Text Available We describe an efficient computational scheme for downward surface flux computations in a vertically inhomogeneous grey planetary atmosphere for different values of solar zenith angle. We start with the basic equations of a recently developed discrete ordinates spectral nodal method, and we derive suitable bidirectional functions whose diffuse components do not depend on the solar zenith angle. We then make use of these bidirectional functions to construct an efficient scheme for computing the downward surface fluxes in a given model atmosphere for a number of solar zenith angles. We illustrate the merit of the computational scheme described here with downward surface flux computations in a three-layer grey model atmosphere for four values of solar zenith angle, and we conclude this article with general remarks and directions for future work.Este artigo descreve um esquema computacional baseado em desenvolvimentos recentes do método espectro-nodal de ordenadas discretas para o cálculo eficiente do fluxo radiativo superficial em uma atmosfera planetária cinza e verticalmente não-homogênea para valores distintos do ângulo zenital solar. A partir das equações básicas do método espectro-nodal de ordenadas discretas, são obtidas funções bidirecionais discretas cujas componentes difusas não dependem do ângulo zenital solar. Com essas funções bidirecionais discretas, é construído um esquema computacional para calcular eficientemente fluxos radiativos superficiais em uma dada atmosfera-modelo para vários ângulos zenitais solares. O mérito computacional do esquema resultante é ilustrado com resultados numéricos para os fluxos radiativos superficiais em uma atmosfera-modelo cinza com três camadas para quatro valores distintos do ângulo zenital solar. Este artigo é finalizado com observações gerais e indicações de trabalhos futuros.

  15. Longwave Imaging for Astronomical Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a compact portable longwave camera for astronomical applications. In Phase 1, we successfully developed the eye of the camera, i.e. the focal...

  16. Revising shortwave and longwave radiation archives in view of possible revisions of the WSG and WISG reference scales: methods and implications

    Science.gov (United States)

    Nyeki, Stephan; Wacker, Stefan; Gröbner, Julian; Finsterle, Wolfgang; Wild, Martin

    2017-08-01

    A large number of radiometers are traceable to the World Standard Group (WSG) for shortwave radiation and the interim World Infrared Standard Group (WISG) for longwave radiation, hosted by the Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre (PMOD/WRC, Davos, Switzerland). The WSG and WISG have recently been found to over- and underestimate radiation values, respectively (Fehlmann et al., 2012; Gröbner et al., 2014), although research is still ongoing. In view of a possible revision of the reference scales of both standard groups, this study discusses the methods involved and the implications on existing archives of radiation time series, such as the Baseline Surface Radiation Network (BSRN). Based on PMOD/WRC calibration archives and BSRN data archives, the downward longwave radiation (DLR) time series over the 2006-2015 period were analysed at four stations (polar and mid-latitude locations). DLR was found to increase by up to 3.5 and 5.4 W m-2 for all-sky and clear-sky conditions, respectively, after applying a WISG reference scale correction and a minor correction for the dependence of pyrgeometer sensitivity on atmospheric integrated water vapour content. Similar increases in DLR may be expected at other BSRN stations. Based on our analysis, a number of recommendations are made for future studies.

  17. Longwave instabilities and patterns in fluids

    CERN Document Server

    Shklyaev, Sergey

    2017-01-01

    This book summarizes the main advances in the field of nonlinear evolution and pattern formation caused by longwave instabilities in fluids. It will allow readers to master the multiscale asymptotic methods and become familiar with applications of these methods in a variety of physical problems.  Longwave instabilities are inherent to a variety of systems in fluid dynamics, geophysics, electrodynamics, biophysics, and many others. The techniques of the derivation of longwave amplitude equations, as well as the analysis of numerous nonlinear equations, are discussed throughout. This book will be of value to researchers and graduate students in applied mathematics, physics, and engineering, in particular within the fields of fluid mechanics, heat and mass transfer theory, and nonlinear dynamics. .

  18. The estimation of the atmospheric longwave radiation

    NARCIS (Netherlands)

    Nowak, H.; Wit, de M.H.; Schellen, H.L.

    1994-01-01

    The paper presents a review of some models to calculate the intensity of the atmospheric longwave radiation upon horizontal plane. This radiation (called also thermal or infrared radiation) may have significant influence on the radiative balance and subseuquently on the thermal balance of the

  19. Downward Movement of Potentially Toxic Elements in Biosolids Amended Soils

    Directory of Open Access Journals (Sweden)

    Silvana Irene Torri

    2012-01-01

    Full Text Available Potentially toxic elements (PTEs in soils are mainly associated with the solid phase, bound to the surface of solid components, or precipitated as minerals. For most PTEs, only a small portion is dissolved in the soil solution. However, there is an interest in following the fate of mobile PTEs in the environment, for a growing amount of evidence indicates that downward movement of PTEs may occur in biosolids amended soils, leading to groundwater contamination. Therefore, it is crucial to understand the factors that control the release of these elements after land application of biosolids, in order to overcome problems related to downward movement of PTEs in the soil profile.

  20. Uncertainty Estimate of Surface Irradiances Computed with MODIS-, CALIPSO-, and CloudSat-Derived Cloud and Aerosol Properties

    Science.gov (United States)

    Kato, Seiji; Loeb, Norman G.; Rutan, David A.; Rose, Fred G.; Sun-Mack, Sunny; Miller, Walter F.; Chen, Yan

    2012-07-01

    Differences of modeled surface upward and downward longwave and shortwave irradiances are calculated using modeled irradiance computed with active sensor-derived and passive sensor-derived cloud and aerosol properties. The irradiance differences are calculated for various temporal and spatial scales, monthly gridded, monthly zonal, monthly global, and annual global. Using the irradiance differences, the uncertainty of surface irradiances is estimated. The uncertainty (1σ) of the annual global surface downward longwave and shortwave is, respectively, 7 W m-2 (out of 345 W m-2) and 4 W m-2 (out of 192 W m-2), after known bias errors are removed. Similarly, the uncertainty of the annual global surface upward longwave and shortwave is, respectively, 3 W m-2 (out of 398 W m-2) and 3 W m-2 (out of 23 W m-2). The uncertainty is for modeled irradiances computed using cloud properties derived from imagers on a sun-synchronous orbit that covers the globe every day (e.g., moderate-resolution imaging spectrometer) or modeled irradiances computed for nadir view only active sensors on a sun-synchronous orbit such as Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation and CloudSat. If we assume that longwave and shortwave uncertainties are independent of each other, but up- and downward components are correlated with each other, the uncertainty in global annual mean net surface irradiance is 12 W m-2. One-sigma uncertainty bounds of the satellite-based net surface irradiance are 106 W m-2 and 130 W m-2.

  1. Spectral Longwave Cloud Radiative Forcing as Observed by AIRS

    Science.gov (United States)

    Blaisdell, John M.; Susskind, Joel; Lee, Jae N.; Iredell, Lena

    2016-01-01

    AIRS V6 products contain the spectral contributions to Outgoing Longwave Radiation (OLR), clear-sky OLR (OLR(sub CLR)), and Longwave Cloud Radiative Forcing (LWCRF) in 16 bands from 100 cm(exp -1) to 3260 cm(exp -1). We show climatologies of selected spectrally resolved AIRS V6 products over the period of September 2002 through August 2016. Spectrally resolved LWCRF can better describe the response of the Earth system to cloud and cloud feedback processes. The spectral LWCRF enables us to estimate the fraction of each contributing factor to cloud forcing, i.e.: surface temperature, mid to upper tropospheric water vapor, and tropospheric temperature. This presentation also compares the spatial characteristics of LWCRF from AIRS, CERES_EBAF Edition-2.8, and MERRA-2. AIRS and CERES LWCRF products show good agreement. The OLR bias between AIRS and CERES is very close to that of OLR(sub CLR). This implies that both AIRS and CERES OLR products accurately account for the effect of clouds on OLR.

  2. Cover Art: River's Edge: Downward, Outward, Upward

    Directory of Open Access Journals (Sweden)

    Jonee Kulman Brigham

    2017-10-01

    Full Text Available Artist's Statement for the cover art of IJPS volume 4, issue 3: River's Edge: Downward, Outward, Upward, 2015. Mixed Media: photograph, inkjet printed on presentation matte of colored pencil over photograph.

  3. A simple formula for the net long-wave radiation flux in the southern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Tomasz Zapadka

    2001-09-01

    Full Text Available This paper discusses problems of estimating the net long-wave radiation flux at the sea surface on the basis of easily measurable meteorological quantities (air and sea surface temperatures, near-surface water vapour pressure, cloudiness. Empirical data and existing formulae are compared. Additionally, an improved formula for the southern Baltic region is introduced, with a systematic error of less than 1 W -2 and a statistical error of less than 20 W -2.

  4. Longwave thermal infrared spectral variability in individual rocks

    Energy Technology Data Exchange (ETDEWEB)

    Balick, Lee K [Los Alamos National Laboratory; Gillespie, Alan [UN. WASHINGTON; French, Andrew [USDA-ARS; Danilina, Iryna [UN. WASHINGTON

    2008-01-01

    A hyperspectral imaging spectrometer measuring in the longwave thermal infrared (7.6-11.6 {micro}m) with a spatial resolution less than 4 mm was used in the field to observe the variability of emissivity spectra within individual rocks. The rocks were obtained commercially, were on the order of 20 cm in size and were selected to have distinct spectral features: they include alabaster (gypsum), soapstone (steatite with talc), obsidian (volcanic glass), norite (plagioclase and orthopyroxene), and 'jasper' (silica with iron oxides). The advantages of using an imaging spectrometer to spectrally characterize these rocks are apparent. Large spectral variations were observed within individual rocks that may be attributed to roughness, surface geometry, and compositional variation. Non-imaging spectrometers would normally miss these variations as would small samples used in laboratory measurements, spatially averaged spectra can miss the optimum spectra for identification materials and spatially localized components of the rock can be obscured.

  5. Self-reflection Orients Visual Attention Downward.

    Science.gov (United States)

    Liu, Yi; Tong, Yu; Li, Hong

    2017-01-01

    Previous research has demonstrated abstract concepts associated with spatial location (e.g., God in the Heavens) could direct visual attention upward or downward, because thinking about the abstract concepts activates the corresponding vertical perceptual symbols. For self-concept, there are similar metaphors (e.g., "I am above others"). However, whether thinking about the self can induce visual attention orientation is still unknown. Therefore, the current study tested whether self-reflection can direct visual attention. Individuals often display the tendency of self-enhancement in social comparison, which reminds the individual of the higher position one possesses relative to others within the social environment. As the individual is the agent of the attention orientation, and high status tends to make an individual look down upon others to obtain a sense of pride, it was hypothesized that thinking about the self would lead to a downward attention orientation. Using reflection of personality traits and a target discrimination task, Study 1 found that, after self-reflection, visual attention was directed downward. Similar effects were also found after friend-reflection, with the level of downward attention being correlated with the likability rating scores of the friend. Thus, in Study 2, a disliked other was used as a control and the positive self-view was measured with above-average judgment task. We found downward attention orientation after self-reflection, but not after reflection upon the disliked other. Moreover, the attentional bias after self-reflection was correlated with above-average self-view. The current findings provide the first evidence that thinking about the self could direct visual-spatial attention downward, and suggest that this effect is probably derived from a positive self-view within the social context.

  6. Longwave infrared observation of urban landscapes

    Science.gov (United States)

    Goward, S. N.

    1981-01-01

    An investigation is conducted regarding the feasibility to develop improved methods for the identification and analysis of urban landscapes on the basis of a utilization of longwave infrared observations. Attention is given to landscape thermal behavior, urban thermal properties, modeled thermal behavior of pavements and buildings, and observed urban landscape thermal emissions. The differential thermal behavior of buildings, pavements, and natural areas within urban landscapes is found to suggest that integrated multispectral solar radiant reflectance and terrestrial radiant emissions data will significantly increase potentials for analyzing urban landscapes. In particular, daytime satellite observations of the considered type should permit better identification of urban areas and an analysis of the density of buildings and pavements within urban areas. This capability should enhance the utility of satellite remote sensor data in urban applications.

  7. Film Boiling on Downward Quenching Hemisphere of Varying Sizes

    Energy Technology Data Exchange (ETDEWEB)

    Chan S. Kim; Kune Y. Suh; Joy L. Rempe; Fan-Bill Cheung; Sang B. Kim

    2004-04-01

    Film boiling heat transfer coefficients for a downward-facing hemispherical surface are measured from the quenching tests in DELTA (Downward-boiling Experimental Laminar Transition Apparatus). Two test sections are made of copper to maintain low Biot numbers. The outer diameters of the hemispheres are 120 mm and 294 mm, respectively. The thickness of all the test sections is 30 mm. The effect of diameter on film boiling heat transfer is quantified utilizing results obtained from the test sections. The measured data are compared with the numerical predictions from laminar film boiling analysis. The measured heat transfer coefficients are found to be greater than those predicted by the conventional laminar flow theory on account of the interfacial wavy motion incurred by the Helmholtz instability. Incorporation of the wavy motion model considerably improves the agreement between the experimental and numerical results in terms of heat transfer coefficient. In addition, the interfacial wavy motion and the quenching process are visualized through a digital camera.

  8. Air pocket removal from downward sloping pipes

    NARCIS (Netherlands)

    Pothof, I.W.M.; Clemens, F.H.L.R.

    2012-01-01

    Air-water flow is an undesired condition in water pipelines and hydropower tunnels. Water pipelines and wastewater pressure mains in particular are subject to air pocket accumulation in downward sloping reaches, such as inverted siphons or terrain slopes. Air pockets cause energy losses and an

  9. Performance tuning Weather Research and Forecasting (WRF) Goddard longwave radiative transfer scheme on Intel Xeon Phi

    Science.gov (United States)

    Mielikainen, Jarno; Huang, Bormin; Huang, Allen H.

    2015-10-01

    Next-generation mesoscale numerical weather prediction system, the Weather Research and Forecasting (WRF) model, is a designed for dual use for forecasting and research. WRF offers multiple physics options that can be combined in any way. One of the physics options is radiance computation. The major source for energy for the earth's climate is solar radiation. Thus, it is imperative to accurately model horizontal and vertical distribution of the heating. Goddard solar radiative transfer model includes the absorption duo to water vapor,ozone, ozygen, carbon dioxide, clouds and aerosols. The model computes the interactions among the absorption and scattering by clouds, aerosols, molecules and surface. Finally, fluxes are integrated over the entire longwave spectrum.In this paper, we present our results of optimizing the Goddard longwave radiative transfer scheme on Intel Many Integrated Core Architecture (MIC) hardware. The Intel Xeon Phi coprocessor is the first product based on Intel MIC architecture, and it consists of up to 61 cores connected by a high performance on-die bidirectional interconnect. The coprocessor supports all important Intel development tools. Thus, the development environment is familiar one to a vast number of CPU developers. Although, getting a maximum performance out of MICs will require using some novel optimization techniques. Those optimization techniques are discusses in this paper. The optimizations improved the performance of the original Goddard longwave radiative transfer scheme on Xeon Phi 7120P by a factor of 2.2x. Furthermore, the same optimizations improved the performance of the Goddard longwave radiative transfer scheme on a dual socket configuration of eight core Intel Xeon E5-2670 CPUs by a factor of 2.1x compared to the original Goddard longwave radiative transfer scheme code.

  10. Spectral model for clear sky atmospheric longwave radiation

    Science.gov (United States)

    Li, Mengying; Liao, Zhouyi; Coimbra, Carlos F. M.

    2018-04-01

    An efficient spectrally resolved radiative model is used to calculate surface downwelling longwave (DLW) radiation (0 ∼ 2500 cm-1) under clear sky (cloud free) conditions at the ground level. The wavenumber spectral resolution of the model is 0.01 cm-1 and the atmosphere is represented by 18 non-uniform plane-parallel layers with pressure in each layer determined on a pressure-based coordinate system. The model utilizes the most up-to-date (2016) HITRAN molecular spectral data for 7 atmospheric gases: H2O, CO2, O3, CH4, N2O, O2 and N2. The MT_CKD model is used to calculate water vapor and CO2 continuum absorption coefficients. Longwave absorption and scattering coefficients for aerosols are modeled using Mie theory. For the non-scattering atmosphere (aerosol free), the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models (ICRCCM) program, with spectral deviations below 0.035 W cm m-2. For a scattering atmosphere with typical aerosol loading, the DLW calculated by the proposed model agrees within 3.08% relative error when compared to measured values at 7 climatologically diverse SURFRAD stations. This relative error is smaller than a calibrated parametric model regressed from data for those same 7 stations, and within the uncertainty (+/- 5 W m-2) of pyrgeometers commonly used for meteorological and climatological applications. The DLW increases by 1.86 ∼ 6.57 W m-2 when compared with aerosol-free conditions, and this increment decreases with increased water vapor content due to overlap with water vapor bands. As expected, the water vapor content at the layers closest to the surface contributes the most to the surface DLW, especially in the spectral region 0 ∼ 700 cm-1. Additional water vapor content (mostly from the lowest 1 km of the atmosphere) contributes to the spectral range of 400 ∼ 650 cm-1. Low altitude aerosols ( ∼ 3.46 km or less) contribute to the surface value of DLW mostly in the

  11. Outgoing Longwave Radiation Daily Climate Data Record (OLR Daily CDR)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The product contains the 1-degree by 1-degree daily mean outgoing longwave radiation flux at the top of the atmosphere derived from HIRS radiance observations...

  12. Effectiveness estimation of camouflage measures with solar radiation and longwave radiation considered

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J.S. [LG Electronics Corporation (Korea); Kauh, S.K. [Seoul National University, Seoul (Korea); Yoo, H.S. [Soongsil University, Seoul (Korea)

    1998-11-01

    Camouflage measures in military purpose utilizes the apparent temperature difference between the target and background, so it is essential to develop thermal analysis program for apparent temperature predictions and to apply some camouflage measures to real military targets for camouflage purpose. In this study, a thermal analysis program including conduction, convection and radiation is developed and the validity of radiation heat transfer terms is examined. The results show that longwave radiation along with solar radiation should be included in order to predict apparent temperature as well as physical temperature exactly. Longwave emissivity variation as an effective camouflage measures is applied to a real M2 tank. From the simulation results, it is found that an effective surface treatment, such as painting of a less emissive material or camouflage, clothing, may provide a temperature similarity or a spatial similarity, resulting in an effective camouflage. (author). 12 refs., 6 figs., 1 tab.

  13. SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST

    Directory of Open Access Journals (Sweden)

    Sugih Sudharma Tjandra

    2015-11-01

    Full Text Available Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.

  14. DOWNWARD CATASTROPHE OF SOLAR MAGNETIC FLUX ROPES

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui, E-mail: zhangqh@mail.ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China)

    2016-07-10

    2.5-dimensional time-dependent ideal magnetohydrodynamic (MHD) models in Cartesian coordinates were used in previous studies to seek MHD equilibria involving a magnetic flux rope embedded in a bipolar, partially open background field. As demonstrated by these studies, the equilibrium solutions of the system are separated into two branches: the flux rope sticks to the photosphere for solutions at the lower branch but is suspended in the corona for those at the upper branch. Moreover, a solution originally at the lower branch jumps to the upper, as the related control parameter increases and reaches a critical value, and the associated jump is here referred to as an upward catastrophe. The present paper advances these studies in three aspects. First, the magnetic field is changed to be force-free; the system still experiences an upward catastrophe with an increase in each control parameter. Second, under the force-free approximation, there also exists a downward catastrophe, characterized by the jump of a solution from the upper branch to the lower. Both catastrophes are irreversible processes connecting the two branches of equilibrium solutions so as to form a cycle. Finally, the magnetic energy in the numerical domain is calculated. It is found that there exists a magnetic energy release for both catastrophes. The Ampère's force, which vanishes everywhere for force-free fields, appears only during the catastrophes and does positive work, which serves as a major mechanism for the energy release. The implications of the downward catastrophe and its relevance to solar activities are briefly discussed.

  15. DOWNWARD CATASTROPHE OF SOLAR MAGNETIC FLUX ROPES

    International Nuclear Information System (INIS)

    Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui

    2016-01-01

    2.5-dimensional time-dependent ideal magnetohydrodynamic (MHD) models in Cartesian coordinates were used in previous studies to seek MHD equilibria involving a magnetic flux rope embedded in a bipolar, partially open background field. As demonstrated by these studies, the equilibrium solutions of the system are separated into two branches: the flux rope sticks to the photosphere for solutions at the lower branch but is suspended in the corona for those at the upper branch. Moreover, a solution originally at the lower branch jumps to the upper, as the related control parameter increases and reaches a critical value, and the associated jump is here referred to as an upward catastrophe. The present paper advances these studies in three aspects. First, the magnetic field is changed to be force-free; the system still experiences an upward catastrophe with an increase in each control parameter. Second, under the force-free approximation, there also exists a downward catastrophe, characterized by the jump of a solution from the upper branch to the lower. Both catastrophes are irreversible processes connecting the two branches of equilibrium solutions so as to form a cycle. Finally, the magnetic energy in the numerical domain is calculated. It is found that there exists a magnetic energy release for both catastrophes. The Ampère's force, which vanishes everywhere for force-free fields, appears only during the catastrophes and does positive work, which serves as a major mechanism for the energy release. The implications of the downward catastrophe and its relevance to solar activities are briefly discussed.

  16. Quantum reflection in the linearly downward potential

    Science.gov (United States)

    Chamnan, N.; Krunavakarn, B.

    2017-09-01

    In this work, the motion of a particle in one dimension under the influence of the linearly downward potential well is studied within the context of the non-relativistic quantum mechanics. The attention is paid on the paradoxical phenomenon of the reflection of a particle that is in contrast between classical and quantum physics. Classically, the reflection effect occurs only at a potential barrier. To demonstrate such counter-intuitive phenomenon, the Schrödinger equation is solved to obtain the reflection coefficient in the scattering state by considering an incident particle that is represented by a monochromatic plane wave having an energy E > 0, propagates freely from left to right, pass through the potential well. The continuity conditions at boundaries give the desired result that is expressed in terms of the Airy functions which depends on the incident energy E, the strength jV 0 j and the range L of the well. The value of the reflection coefficient R lies in the interval 0 < R < 1, and its behavior is the decreasing function with respect to the range L.

  17. Decadal evolution of the surface energy budget during the fast warming and global warming hiatus periods in the ERA-interim

    Science.gov (United States)

    Hu, Xiaoming; Sejas, Sergio A.; Cai, Ming; Taylor, Patrick C.; Deng, Yi; Yang, Song

    2018-05-01

    The global-mean surface temperature has experienced a rapid warming from the 1980s to early-2000s but a muted warming since, referred to as the global warming hiatus in the literature. Decadal changes in deep ocean heat uptake are thought to primarily account for the rapid warming and subsequent slowdown. Here, we examine the role of ocean heat uptake in establishing the fast warming and warming hiatus periods in the ERA-Interim through a decomposition of the global-mean surface energy budget. We find the increase of carbon dioxide alone yields a nearly steady increase of the downward longwave radiation at the surface from the 1980s to the present, but neither accounts for the fast warming nor warming hiatus periods. During the global warming hiatus period, the transfer of latent heat energy from the ocean to atmosphere increases and the total downward radiative energy flux to the surface decreases due to a reduction of solar absorption caused primarily by an increase of clouds. The reduction of radiative energy into the ocean and the surface latent heat flux increase cause the ocean heat uptake to decrease and thus contribute to the slowdown of the global-mean surface warming. Our analysis also finds that in addition to a reduction of deep ocean heat uptake, the fast warming period is also driven by enhanced solar absorption due predominantly to a decrease of clouds and by enhanced longwave absorption mainly attributed to the air temperature feedback.

  18. Radiative and Thermal Impacts of Smoke Aerosol Longwave Absorption during Fires in the Moscow Region in Summer 2010

    Science.gov (United States)

    Gorchakova, I. A.; Mokhov, I. I.; Anikin, P. P.; Emilenko, A. S.

    2018-03-01

    The aerosol longwave radiative forcing of the atmosphere and heating rate of the near-surface aerosol layer are estimated for the extreme smoke conditions in the Moscow region in summer 2010. Thermal radiation fluxes in the atmosphere are determined using the integral transmission function and semiempirical aerosol model developed on the basis of standard aerosol models and measurements at the Zvenigorod Scientific Station, Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences. The aerosol radiative forcing reached 33 W/m2 at the lower atmospheric boundary and ranged between-1.0 and 1.0 W/m2 at the upper atmospheric boundary. The heating rate of the 10-m atmospheric layer near surface was up to 0.2 K/h during the maximum smoke conditions on August 7-9. The sensitivity of the aerosol longwave radiative forcing to the changes in the aerosol absorption coefficient and aerosol optical thickness are estimated.

  19. SUNYA Regional Climate Model Simulations of East Asia Summer Monsoon: Effects of Cloud Vertical Structure on the Surface Energy Balance

    Directory of Open Access Journals (Sweden)

    Wei Gong and Wei-Chyung Wang

    2007-01-01

    Full Text Available We used the State University of New York at Albany (SUNYA regional climate model to study the effect of cloud vertical distribution in affecting the surface energy balance of the East Asia summer monsoon (EASM. Simulations were conducted for the summers of 1988 and 1989, during which large contrast in the intra-seasonal cloud radiative forcing (CRF was observed at the top of the atmosphere. The model results indicate that both the high and low clouds are persistent throughout the summer months in both years. Because of large cloud water, low clouds significantly reduce the solar radiation flux reaching the surface, which nevertheless still dominate the surface energy balance, accounting for more than 50% of the surface heating. The low clouds also contribute significantly the downward longwave radiation to the surface with values strongly dependent on the cloud base temperature. The presence of low clouds effectively decreases the temperature and moisture gradients near surface, resulting in a substantial decrease in the sensible and latent heat fluxes from surface, which partially compensate the decrease of the net radiative cooling of the surface. For example, in the two days, May 8 and July 11 of 1988, the total cloud cover of 80% is simulated, but the respective low cloud cover (water was 63% (114 gm-2 and 22% (21 gm-2. As a result, the downward solar radiation is smaller by 161 Wm-2 in May 8. On the other hand, the cloud temperature was _ lower, yielding 56 Wm-2 smaller downward longwave radiation. The near surface temperature and gradient is more than _ smaller (and moisture gradient, leading to 21 and 81 Wm-2 smaller sensible heat and latent heat fluxes. It is also demonstrated that the model is capable to reproduce the intraseasonal variation of shortwave CRF, and catches the relationship between total cloud cover and SW CRF. The model results show the dominance of high cloud on the regional mean longwave CRF and low cloud on the intra

  20. Longwave scattering effects on fluxes in broken cloud fields

    Energy Technology Data Exchange (ETDEWEB)

    Takara, E.E.; Ellingson, R.G. [Univ. of Maryland, College Park, MD (United States)

    1996-04-01

    The optical properties of clouds in the radiative energy balance are important. Most works on the effects of scattering have been in the shortwave; but longwave effects can be significant. In this work, the fluxes above and below a single cloud layer are presented, along with the errors in assuming flat black plate clouds or black clouds. The predicted fluxes are the averaged results of analysis of several fields with the same cloud amount.

  1. Experimental study for flow regime of downward air-water two-phase flow in a vertical narrow rectangular channel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T. H.; Yun, B. J.; Jeong, J. H. [Pusan National University, Geunjeong-gu, Busan (Korea, Republic of)

    2015-05-15

    Studies were mostly about flow in upward flow in medium size circular tube. Although there are great differences between upward and downward flow, studies on vertical upward flow are much more active than those on vertical downward flow in a channel. In addition, due to the increase of surface forces and friction pressure drop, the pattern of gas-liquid two-phase flow bounded to the gap of inside the rectangular channel is different from that in a tube. The downward flow in a rectangular channel is universally applicable to cool the plate type nuclear fuel in research reactor. The sub-channel of the plate type nuclear fuel is designed with a few millimeters. Downward air-water two-phase flow in vertical rectangular channel was experimentally observed. The depth, width, and length of the rectangular channel is 2.35 mm, 66.7 mm, and 780 mm, respectively. The test section consists of transparent acrylic plates confined within a stainless steel frame. The flow patterns of the downward flow in high liquid velocity appeared to be similar to those observed in previous studies with upward flow. In downward flow, the transition lines for bubbly-slug and slug-churn flow shift to left in the flow regime map constructed with abscissa of the superficial gas velocity and ordinate of the superficial liquid velocity. The flow patterns observed with downward flow at low liquid velocity are different from those with upward flow.

  2. Downward continuation and tilt derivative of magnetic data for ...

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... Downward continuation; tilt derivative; magnetic data; coal fire mapping; Jharia coal field;. India. 1. .... of seams are thin and not suitable for mining but have the ...... Theory and Application; McGraw Hill Education (India).

  3. Coarse-graining as a downward causation mechanism

    Science.gov (United States)

    Flack, Jessica C.

    2017-11-01

    Downward causation is the controversial idea that `higher' levels of organization can causally influence behaviour at `lower' levels of organization. Here I propose that we can gain traction on downward causation by being operational and examining how adaptive systems identify regularities in evolutionary or learning time and use these regularities to guide behaviour. I suggest that in many adaptive systems components collectively compute their macroscopic worlds through coarse-graining. I further suggest we move from simple feedback to downward causation when components tune behaviour in response to estimates of collectively computed macroscopic properties. I introduce a weak and strong notion of downward causation and discuss the role the strong form plays in the origins of new organizational levels. I illustrate these points with examples from the study of biological and social systems and deep neural networks. This article is part of the themed issue 'Reconceptualizing the origins of life'.

  4. The Aggregate Supply Curve: Keynes and Downwardly Sticky Money Wages.

    Science.gov (United States)

    Wells, Paul

    1985-01-01

    Keynes's explanation of both the rationale underlying downwardly sticky money wages and the consequences this phenomenon has for macroeconomic theory are reviewed. An aggregate supply curve appropriate to today's economy is then interpreted. (Author/RM)

  5. Flexible Consumers Reserving Electricity and Offering Profitable Downward Regulation

    OpenAIRE

    Höning, Nicolas; La Poutré, Han; Strunz, K.

    2012-01-01

    htmlabstractPrevious work on demand response in smart grids considers dynamic real-time prices, but has so far neglected to consider how consumers can also be involved in planning ahead, both for scheduling of consumption and reserving their ability to regulate downward during balancing. This work models a flexible consumer in a novel two-settlement electricity auction. The consumer buys electricity on an ahead market and offers downward regulation on the balancing market. Bidding in two- set...

  6. High intersubband absorption in long-wave quantum well infrared photodetector based on waveguide resonance

    Science.gov (United States)

    Zheng, Yuanliao; Chen, Pingping; Ding, Jiayi; Yang, Heming; Nie, Xiaofei; Zhou, Xiaohao; Chen, Xiaoshuang; Lu, Wei

    2018-06-01

    A hybrid structure consisting of periodic gold stripes and an overlaying gold film has been proposed as the optical coupler of a long-wave quantum well infrared photodetector. Absorption spectra and field distributions of the structure at back-side normal incidence are calculated by the finite difference time-domain method. The results indicate that the intersubband absorption can be greatly enhanced based on the waveguide resonance as well as the surface plasmon polariton (SPP) mode. With the optimized structural parameters of the periodic gold stripes, the maximal intersubband absorption can exceed 80%, which is much higher than the SPP-enhanced intersubband absorption (the one of the standard device. The relationship between the structural parameters and the waveguide resonant wavelength is derived. Other advantages of the efficient optical coupling based on waveguide resonance are also discussed.

  7. Macrokinetic determination of isopropanol removal using a downward flow biofilter

    Directory of Open Access Journals (Sweden)

    Vissanu Meeyoo

    2004-02-01

    Full Text Available Biofiltration is a process for eliminating contaminants in air using microorganisms immobilized on a surface of solid support media. This technique has been used successfully to control a number of air contaminants such as odors, Volatile Organic Compounds (VOCs, and Hazardous Air Pollutants (HAPs due to its economic attraction.Microorganisms obtained from local activated sludge (Huay-Kwang wastewater treatment plant (Bangkok, Thailand were selectively enriched and inoculated to the biofilter. The downward flow biofilterwas chosen, due to the ease of water compensation at the dry zone, to operate continuously for more than 3 months under various concentrations of isopropanol alcohol (IPA input at a constant filtered air flow rate of 3 L/min. The maximum IPA elimination capacity of 276 g/m3-h was achieved at the IPA inlet of 342 g/m3-h with acetone production rate of 56 g/m3-h as the intermediate. It was also found that the acetone vapour was partly degraded by the acetone-utilizing microorganisms before leaving the bed. In order to understand the transport phenomena of biofiltration, it is necessary to consider the kinetic behavior of the bioreaction. Therefore, this paper introduces Wani’s method of macrokinetic determination based on the simple Monod kinetic (Wani, Lau and Branion, 1999. In this study, the maximum reaction rate per unit volume (Rm and the Monod constant (KM were found to be 0.12 g/m3 -s and 2.72 g/m3 respectively.

  8. Spatial and Temporal Variabilities of Solar and Longwave Radiation Fluxes below a Coniferous Forest in the French Alps

    Science.gov (United States)

    Sicart, J. E.; Ramseyer, V.; Lejeune, Y.; Essery, R.; Webster, C.; Rutter, N.

    2017-12-01

    At high altitudes and latitudes, snow has a large influence on hydrological processes. Large fractions of these regions are covered by forests, which have a strong influence on snow accumulation and melting processes. Trees absorb a large part of the incoming shortwave radiation and this heat load is mostly dissipated as longwave radiation. Trees shelter the snow surface from wind, so sub-canopy snowmelt depends mainly on the radiative fluxes: vegetation attenuates the transmission of shortwave radiation but enhances longwave irradiance to the surface. An array of 13 pyranometers and 11 pyrgeometers was deployed on the snow surface below a coniferous forest at the CEN-MeteoFrance Col de Porte station in the French Alps (1325 m asl) during the 2017 winter in order to investigate spatial and temporal variabilities of solar and infrared irradiances in different meteorological conditions. Sky view factors measured with hemispherical photographs at each radiometer location were in a narrow range from 0.2 to 0.3. The temperature of the vegetation was measured with IR thermocouples and an IR camera. In clear sky conditions, the attenuation of solar radiation by the canopy reached 96% and its spatial variability exceeded 100 W m-2. Longwave irradiance varied by 30 W m-2 from dense canopy to gap areas. In overcast conditions, the spatial variabilities of solar and infrared irradiances were reduced and remained closely related to the sky view factor. A simple radiative model taking into account the penetration through the canopy of the direct and diffuse solar radiation, and isotropic infrared emission of the vegetation as a blackbody emitter, accurately reproduced the dynamics of the radiation fluxes at the snow surface. Model results show that solar transmissivity of the canopy in overcast conditions is an excellent proxy of the sky view factor and the emitting temperature of the vegetation remained close to the air temperature in this typically dense Alpine forest.

  9. Flexible Consumers Reserving Electricity and Offering Profitable Downward Regulation

    NARCIS (Netherlands)

    N.F. Höning (Nicolas); J.A. La Poutré (Han); K. Strunz

    2012-01-01

    htmlabstractPrevious work on demand response in smart grids considers dynamic real-time prices, but has so far neglected to consider how consumers can also be involved in planning ahead, both for scheduling of consumption and reserving their ability to regulate downward during balancing. This work

  10. Longwave indirect effect of mineral dusts on ice clouds

    Directory of Open Access Journals (Sweden)

    Q. Min

    2010-08-01

    Full Text Available In addition to microphysical changes in clouds, changes in nucleation processes of ice cloud due to aerosols would result in substantial changes in cloud top temperature as mildly supercooled clouds are glaciated through heterogenous nucleation processes. Measurements from multiple sensors on multiple observing platforms over the Atlantic Ocean show that the cloud effective temperature increases with mineral dust loading with a slope of +3.06 °C per unit aerosol optical depth. The macrophysical changes in ice cloud top distributions as a consequence of mineral dust-cloud interaction exert a strong cooling effect (up to 16 Wm−2 of thermal infrared radiation on cloud systems. Induced changes of ice particle size by mineral dusts influence cloud emissivity and play a minor role in modulating the outgoing longwave radiation for optically thin ice clouds. Such a strong cooling forcing of thermal infrared radiation would have significant impacts on cloud systems and subsequently on climate.

  11. Longwave emission trends over Africa and implications for Atlantic hurricanes

    Science.gov (United States)

    Zhang, Lei; Rechtman, Thomas; Karnauskas, Kristopher B.; Li, Laifang; Donnelly, Jeffrey P.; Kossin, James P.

    2017-09-01

    The latitudinal gradient of outgoing longwave radiation (OLR) over Africa is a skillful and physically based predictor of seasonal Atlantic hurricane activity. The African OLR gradient is observed to have strengthened during the satellite era, as predicted by state-of-the-art global climate models (GCMs) in response to greenhouse gas forcing. Prior to the satellite era and the U.S. and European clean air acts, the African OLR gradient weakened due to aerosol forcing of the opposite sign. GCMs predict a continuation of the increasing OLR gradient in response to greenhouse gas forcing. Assuming a steady linear relationship between African easterly waves and tropical cyclogenesis, this result suggests a future increase in Atlantic tropical cyclone frequency by 10% (20%) at the end of the 21st century under the RCP 4.5 (8.5) forcing scenario.

  12. Overhead longwave infrared hyperspectral material identification using radiometric models

    Energy Technology Data Exchange (ETDEWEB)

    Zelinski, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2018-01-09

    Material detection algorithms used in hyperspectral data processing are computationally efficient but can produce relatively high numbers of false positives. Material identification performed as a secondary processing step on detected pixels can help separate true and false positives. This paper presents a material identification processing chain for longwave infrared hyperspectral data of solid materials collected from airborne platforms. The algorithms utilize unwhitened radiance data and an iterative algorithm that determines the temperature, humidity, and ozone of the atmospheric profile. Pixel unmixing is done using constrained linear regression and Bayesian Information Criteria for model selection. The resulting product includes an optimal atmospheric profile and full radiance material model that includes material temperature, abundance values, and several fit statistics. A logistic regression method utilizing all model parameters to improve identification is also presented. This paper details the processing chain and provides justification for the algorithms used. Several examples are provided using modeled data at different noise levels.

  13. Liquid velocity in upward and downward air-water flows

    International Nuclear Information System (INIS)

    Sun Xiaodong; Paranjape, Sidharth; Kim, Seungjin; Ozar, Basar; Ishii, Mamoru

    2004-01-01

    Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral laser Doppler anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void-weighted area-averaged drift velocity were obtained based on the definitions

  14. Numerical analysis of transient heat conduction in downward-facing curved sections during quenching

    International Nuclear Information System (INIS)

    Gao, C.; El-Genk, M.S.

    1996-01-01

    Pool boiling from downward-facing surfaces is of interest in many applications such as cooling of electric cables, handling of containers of hazardous liquids and external cooling of nuclear reactor vessels. Here, a two-dimensional numerical analysis was performed to determine pool boiling curves from downward-facing curved stainless-steel and copper surfaces during quenching in saturated water. To ensure stability and accuracy of the numerical solution, the alternating direction implicit (ADI) method based on finite control volume representations was employed. A time dependent boundary condition was provided by the measured temperature at nine interior locations near the boiling surface. Best results were obtained using a grid of 20x20 CVs and a non-iterative approach. Calculated temperatures near the top surface of the metal sections agreed with measured values to within 0.5 K and 2.5 K for the copper and stainless-steel sections, respectively. The running time on a Pentium 90 MHz PC for the entire boiling curve was 7% of the real transient time and 4% of that of a simplified Gaussian elimination (SGE) method for the Crank-Nicolson scheme

  15. Handheld Longwave Infrared Camera Based on Highly-Sensitive Quantum Well Infrared Photodetectors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a compact handheld longwave infrared camera based on quantum well infrared photodetector (QWIP) focal plane array (FPA) technology. Based on...

  16. High Quantum Efficiency 1024x1024 Longwave Infrared SLS FPA and Camera, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a high quantum efficiency (QE) 1024x1024 longwave infrared focal plane array (LWIR FPA) and CAMERA with ~ 12 micron cutoff wavelength made from...

  17. NOAA Climate Data Record (CDR) of Monthly Outgoing Longwave Radiation (OLR), Version 2.2-1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Climate Data Record (CDR) of monthly mean High Resolution Infrared Radiation Sounder (HIRS) Outgoing Longwave Radiation (OLR) flux at the top of the atmosphere...

  18. NOAA Climate Data Record (CDR) of Daily Outgoing Longwave Radiation (OLR), Version 1.2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Climate Data Record (CDR) contains the daily mean Outgoing Longwave Radiation (OLR) time series in global 1 degree x 1 degree equal-angle gridded maps spanning...

  19. TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, 2000-present, Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Incoming Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  20. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, 2000-present, Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Incoming Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  1. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 2000-present, Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Incoming Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  2. TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, 2000-present, Net Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  3. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 2000-present, Net Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  4. TAO/TRITON, RAMA, and PIRATA Buoys, 5-Day, 2000-present, Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has 5-day Incoming Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  5. TAO/TRITON, RAMA, and PIRATA Buoys, 5-Day, 2000-present, Net Longwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has 5-day Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  6. NUCAPS: NOAA Unique Combined Atmospheric Processing System Outgoing Longwave Radiation (OLR)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of Outgoing Longwave Radiation (OLR) from the NOAA Unique Combined Atmospheric Processing System (NUCAPS). NUCAPS was developed by the...

  7. Shortwave and longwave radiative contributions to global warming under increasing CO2

    Science.gov (United States)

    Donohoe, Aaron; Armour, Kyle C.; Pendergrass, Angeline G.; Battisti, David S.

    2014-01-01

    In response to increasing concentrations of atmospheric CO2, high-end general circulation models (GCMs) simulate an accumulation of energy at the top of the atmosphere not through a reduction in outgoing longwave radiation (OLR)—as one might expect from greenhouse gas forcing—but through an enhancement of net absorbed solar radiation (ASR). A simple linear radiative feedback framework is used to explain this counterintuitive behavior. It is found that the timescale over which OLR returns to its initial value after a CO2 perturbation depends sensitively on the magnitude of shortwave (SW) feedbacks. If SW feedbacks are sufficiently positive, OLR recovers within merely several decades, and any subsequent global energy accumulation is because of enhanced ASR only. In the GCM mean, this OLR recovery timescale is only 20 y because of robust SW water vapor and surface albedo feedbacks. However, a large spread in the net SW feedback across models (because of clouds) produces a range of OLR responses; in those few models with a weak SW feedback, OLR takes centuries to recover, and energy accumulation is dominated by reduced OLR. Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR. PMID:25385628

  8. Shortwave and longwave radiative contributions to global warming under increasing CO2.

    Science.gov (United States)

    Donohoe, Aaron; Armour, Kyle C; Pendergrass, Angeline G; Battisti, David S

    2014-11-25

    In response to increasing concentrations of atmospheric CO2, high-end general circulation models (GCMs) simulate an accumulation of energy at the top of the atmosphere not through a reduction in outgoing longwave radiation (OLR)—as one might expect from greenhouse gas forcing—but through an enhancement of net absorbed solar radiation (ASR). A simple linear radiative feedback framework is used to explain this counterintuitive behavior. It is found that the timescale over which OLR returns to its initial value after a CO2 perturbation depends sensitively on the magnitude of shortwave (SW) feedbacks. If SW feedbacks are sufficiently positive, OLR recovers within merely several decades, and any subsequent global energy accumulation is because of enhanced ASR only. In the GCM mean, this OLR recovery timescale is only 20 y because of robust SW water vapor and surface albedo feedbacks. However, a large spread in the net SW feedback across models (because of clouds) produces a range of OLR responses; in those few models with a weak SW feedback, OLR takes centuries to recover, and energy accumulation is dominated by reduced OLR. Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR.

  9. Impact of CO/sub 2/ on cooling of snow and water surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, B [Computer Sciences Corp., Silver Spring, MD; Kukla, G

    1979-08-23

    The levels of CO/sub 2/ in the atmosphere are being increased by the burning of fossil fuels and reduction of biomass. It has been calculated that the increase in CO/sub 2/ levels should lead to global warming because of increased absorption by the atmosphere of terrestrial longwave radiation in the far IR (> 5 ..mu..m). From model computations, CO/sub 2/ is expected to produce the largest climatic effect in high latitudes by reducing the size of ice and snow fields. We present here computations of spectral radiative transfer and scattering within a snow pack and water. The results suggest that CO/sub 2/ significantly reduces the shortwave energy absorbed by the surface of snow and water. The energy deficit, when not compensated by downward atmospheric radiation, may delay the recrystallisation of snow and dissipation of packice and result in a cooling rather than a warming effect.

  10. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T.

    1995-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  11. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T

    1996-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  12. Interfacial structures in downward two-phase bubbly flow

    International Nuclear Information System (INIS)

    Paranjape, S.S.; Kim, S.; Ishii, M.; Kelly, J.

    2003-01-01

    Downward two-phase flow was studied considering its significance in view of Light Water Reactor Accidents (LWR) such as Loss of Heat Sink (LOHS) by feed water loss or secondary pipe break. The flow studied, was an adiabatic, air-water, co-current, vertically downward two-phase flow. The experimental test sections had internal hydraulic diameters of 25.4 mm and 50.8 mm. Flow regime map was obtained using the characteristic signals obtained from an impedance void meter, employing neural network based identification methodology to minimize the subjective judgment in determining the flow regimes. A four sensor conductivity probe was used to measure the local two phase flow parameters, which characterize the interfacial structures. The local time averaged two-phase flow parameters measured were: void fraction (α), interfacial area concentration (a i ), bubble velocity (v g ), and Sauter mean diameter (D Sm ). The flow conditions were from the bubbly flow regime. The local profiles of these parameters as well as their axial development revealed the nature of the interfacial structures and the bubble interaction mechanisms occurring in the flow. Furthermore, this study provided a good database for the development of the interfacial area transport equation, which dynamically models the changes in the interfacial area along the flow field. An interfacial area transport equation was developed for downward flow based on that developed for the upward flow, with certain modifications in the bubble interaction terms. The area averaged values of the interfacial area concentration were compared with those predicted by the interfacial area transport model. (author)

  13. Long-wave Irradiance Measurement and Modeling during Snowmelt, a Case Study in the Yukon Territory, Canada

    Science.gov (United States)

    Sicart, J.; Essery, R.; Pomeroy, J.

    2004-12-01

    At high latitudes, long-wave radiation emitted by the atmosphere and solar radiation can provide similar amounts of energy for snowmelt due to the low solar elevation and the high albedo of snow. This paper investigates temporal and spatial variations of long-wave irradiance at the snow surface in an open sub-Arctic environment. Measurements were conducted in the Wolf Creek Research Basin, Yukon Territory, Canada (60°36'N, 134°57'W) during the springs of 2002, 2003 and 2004. The main causes of temporal variability are air temperature and cloud cover, especially in the beginning of the melting period when the atmosphere is still cold. Spatial variability was investigated through a sensitivity study to sky view factors and to temperatures of surrounding terrain. The formula of Brutsaert gives a useful estimation of the clear-sky irradiance at hourly time steps. Emission by clouds was parameterized at the daily time scale from the atmospheric attenuation of solar radiation. The inclusion of air temperature variability does not much improve the calculation of cloud emission.

  14. Effect of the Aligned Flow Obstacles on Downward-Facing CHF in an Inclined Rectangular Channel

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ui ju; Son, Hong Hyun; Seo, Gwang Hyeok; Jeun, Gyoo Dong; Kim, Sung Joong [Hanyang, Seoul (Korea, Republic of)

    2016-05-15

    The cooling channel consists of the inclined (10 .deg. ) portion of the downward facing heating channel and vertical portion of the heating channel. Features unique to flow boiling with the downward-facing heater surface in the inclined cooling channel where the studs are installed have drawn a considerable attention. That's because prior studies on boiling crisis indicate the orientation of the heated wall can exert substantial influence on CHF. Especially, the concentration of the vapor near the downward facing heater surface makes this region susceptible to premature boiling crisis when compared to vertical or upward-facing heated wall. Also, the installed studs could cause a partial flow blockage, and distort the flow streamline. Due to the distortion, stagnation points may occur in the cooling channel, promoting the concentration of the vapor near the heated wall. Then, the locally degraded heat transfer around the points may result in the formation of vapor pocket. The primary objective of this study is to make available experimental data on the CHF values varying the shape of studs and to improve understanding of the mechanism of flow boiling crisis associated with the aligned flow obstructions by means of visual experimental study. This study presents experimental data for subcooled flow boiling of water at atmospheric pressure and low mass flux conditions. The major outcomes from this investigation can be summarized as follows: (1) The CHF value from bare test section is -320kW/m{sup 2} , significantly lower than the values from the existing correlations even considering the uncertainty in the experiments. (2) The CHF value is remarkably decreased as columnar structures are installed in the channel. It is confirmed that formation and extinction of local dryout occurs repeatedly just behind the first stud at heat flux of -160 kW/m{sup 2}.

  15. Lidar Penetration Depth Observations for Constraining Cloud Longwave Feedbacks

    Science.gov (United States)

    Vaillant de Guelis, T.; Chepfer, H.; Noel, V.; Guzman, R.; Winker, D. M.; Kay, J. E.; Bonazzola, M.

    2017-12-01

    Satellite-borne active remote sensing Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations [CALIPSO; Winker et al., 2010] and CloudSat [Stephens et al., 2002] provide direct measurements of the cloud vertical distribution, with a very high vertical resolution. The penetration depth of the laser of the lidar Z_Opaque is directly linked to the LongWave (LW) Cloud Radiative Effect (CRE) at Top Of Atmosphere (TOA) [Vaillant de Guélis et al., in review]. In addition, this measurement is extremely stable in time making it an excellent observational candidate to verify and constrain the cloud LW feedback mechanism [Chepfer et al., 2014]. In this work, we present a method to decompose the variations of the LW CRE at TOA using cloud properties observed by lidar [GOCCP v3.0; Guzman et al., 2017]. We decompose these variations into contributions due to changes in five cloud properties: opaque cloud cover, opaque cloud altitude, thin cloud cover, thin cloud altitude, and thin cloud emissivity [Vaillant de Guélis et al., in review]. We apply this method, in the real world, to the CRE variations of CALIPSO 2008-2015 record, and, in climate model, to LMDZ6 and CESM simulations of the CRE variations of 2008-2015 period and of the CRE difference between a warm climate and the current climate. In climate model simulations, the same cloud properties as those observed by CALIOP are extracted from the CFMIP Observation Simulator Package (COSP) [Bodas-Salcedo et al., 2011] lidar simulator [Chepfer et al., 2008], which mimics the observations that would be performed by the lidar on board CALIPSO satellite. This method, when applied on multi-model simulations of current and future climate, could reveal the altitude of cloud opacity level observed by lidar as a strong constrain for cloud LW feedback, since the altitude feedback mechanism is physically explainable and the altitude of cloud opacity accurately observed by lidar.

  16. A Paradigm shift to an Old Scheme for Outgoing Longwave Radiation

    Science.gov (United States)

    McDonald, Alastair B.

    2016-04-01

    There are many cases where the climate models do not agree with the empirical data. For instance, the data from radiosondes (and MSUs) do not show the amount of warming in the upper troposphere that is predicted by the models (Thorne et al. 2011). The current scheme for outgoing longwave radiation can be traced back to the great 19th Century French mathematician J-B Joseph Fourier. His anachronistic idea was that the radiation balance at the top of the atmosphere (TOA) is maintained by the conduction of heat from the surface (Fourier 1824). It was based on comparing the atmosphere to the 18th Century Swiss scientist H-B de Saussure's hotbox which he had invented to show that solar radiation is only slightly absorbed by the atmosphere. Saussure also showed that thermal radiation existed and argued that the warmth of the air near the surface of the Earth is due to absorption of that infra red radiation (Saussure 1786). Hence a paradigm shift to Saussure's scheme, where the thermal radiation is absorbed at the base of the atmosphere, rather than throughout the atmosphere as in Fourier's scheme, may solve many climate models problems. In this new paradigm the boundary layer continually exchanges radiation with the surface. Thus only at two instants during the day is there no net gain or loss of heat by the boundary layer from the surface, and so that layer is not in LTE. Moreover, since the absorption of outgoing longwave radiation is saturated within the boundary layer, it has little influence on the TOA balance. That balance is mostly maintained by changes in albedo, e.g. clouds and ice sheets. Use of this paradigm can explain why the excess warming in south western Europe was caused by water vapour close to the surface (Philipona et al. 2005), and may also explain why there are difficulties in closing the surface radiation balance (Wild et al. 2013) and in modelling abrupt climate change (White et al. 2013). References: Fourier, Joseph. 1824. 'Remarques G

  17. DOWNWARD SLOPING DEMAND CURVES FOR STOCK AND LEVERAGE

    Directory of Open Access Journals (Sweden)

    Liem Pei Fun

    2006-01-01

    Full Text Available This research attempts to investigate the effect of downward sloping demand curves for stock on firms' financing decisions. For the same size of equity issuance, firms with steeper slope of demand curves for their stocks experience a larger price drop in their share price compare to their counterparts. As a consequence, firms with a steeper slope of demand curves are less likely to issue equity and hence they have higher leverage ratios. This research finds that the steeper the slope of demand curve for firm's stock, the higher the actual leverage of the firm. Furthermore, firms with a steeper slope of demand curves have higher target leverage ratios, signifying that these firms prefer debt to equity financing in order to avoid the adverse price impact of equity issuance on their share price.

  18. CAUSES: On the Role of Surface Energy Budget Errors to the Warm Surface Air Temperature Error Over the Central United States

    Science.gov (United States)

    Ma, H.-Y.; Klein, S. A.; Xie, S.; Zhang, C.; Tang, S.; Tang, Q.; Morcrette, C. J.; Van Weverberg, K.; Petch, J.; Ahlgrimm, M.; Berg, L. K.; Cheruy, F.; Cole, J.; Forbes, R.; Gustafson, W. I.; Huang, M.; Liu, Y.; Merryfield, W.; Qian, Y.; Roehrig, R.; Wang, Y.-C.

    2018-03-01

    Many weather forecast and climate models simulate warm surface air temperature (T2m) biases over midlatitude continents during the summertime, especially over the Great Plains. We present here one of a series of papers from a multimodel intercomparison project (CAUSES: Cloud Above the United States and Errors at the Surface), which aims to evaluate the role of cloud, radiation, and precipitation biases in contributing to the T2m bias using a short-term hindcast approach during the spring and summer of 2011. Observations are mainly from the Atmospheric Radiation Measurement Southern Great Plains sites. The present study examines the contributions of surface energy budget errors. All participating models simulate too much net shortwave and longwave fluxes at the surface but with no consistent mean bias sign in turbulent fluxes over the Central United States and Southern Great Plains. Nevertheless, biases in the net shortwave and downward longwave fluxes as well as surface evaporative fraction (EF) are contributors to T2m bias. Radiation biases are largely affected by cloud simulations, while EF bias is largely affected by soil moisture modulated by seasonal accumulated precipitation and evaporation. An approximate equation based upon the surface energy budget is derived to further quantify the magnitudes of radiation and EF contributions to T2m bias. Our analysis ascribes that a large EF underestimate is the dominant source of error in all models with a large positive temperature bias, whereas an EF overestimate compensates for an excess of absorbed shortwave radiation in nearly all the models with the smallest temperature bias.

  19. Design of Hemispherical Downward-Facing Vessel for Critical Heat Flux Experiment

    International Nuclear Information System (INIS)

    Hwang, J. S.; Suh, K. Y.

    2009-01-01

    The in-vessel retention (IVR) is one of major severe accident management strategies adopted by some operating nuclear power plants during a severe accident. The recent Shin-Gori Units 3 and 4 of the Advanced Power Reactor 1400 MWe (APR1400) have adopted the external reactor vessel cooling (ERVC) by reactor cavity flooding as major severe accident management strategy. The ERVC in the APR1400 design resorts to active flooding system using thermal insulator. The Corium Attack Stopper Apparatus Spherical Channel (CASA SC) tests are conducted to measure the critical power and critical heat flux (CHF) on a downward hemispherical vessel scaled down from the APR1400 lower head by 1/10 on a linear scale. CASA is designed through scaling and thermal analysis to simulate the APR1400 vessel and thermal insulator. The heated vessel of CASA SC represents the external surface of a hemisphere submerged vessel in water. The heated vessel plays an important role in the ERVC experiment depending on the configuration of oxide pool and metallic layer. Hand calculation and computational analysis are performed to produce high heat flux from the downward facing hemisphere in excess of 1 MW/m 2

  20. Distribution and Downward Movement of Pasteuria penetrans in Field Soil.

    Science.gov (United States)

    Cetintas, R; Dickson, D W

    2005-06-01

    Endospores of Pasteuria penetrans were evaluated for their vertical distribution in field soil and their downward movement through soil in the laboratory. In the field trial, the number of endospores attached to second-stage juveniles (J2) of Meloidogyne arenaria race 1 varied greatly in different soil depths. There were higher percentages of J2 with endospores attached in former weed fallow plots during the first 3 years of growing peanut than in former bahiagrass and rhizomal peanut plots (P 0.05). In laboratory trials, P. penetrans endospores were observed to move throughout the soil through the percolation of water. After one application of water, some endospores were detected 25 to 37.5 cm deep. Endospores were present at the greatest depth, 37.5 to 50 cm, after the third application of water. These results indicate that rain or water applications by irrigation are likely to move endospores to deeper levels of the soil, but the majority of endospores remain in the upper 0-to-30-cm depth.

  1. Numerical simulations of downward convective overshooting in giants

    Science.gov (United States)

    Tian, Chun-Lin; Deng, Li-Cai; Chan, Kwing-Lam

    2009-09-01

    An attempt at understanding downward overshooting in the convective envelopes of post-main-sequence stars has been made on the basis of three-dimensional large-eddy simulations, using artificially modified OPAL opacity and taking into account radiation and ionization in the equation of state. Two types of star, an intermediate-mass star and a massive star, were considered. To avoid a long thermal relaxation time of the intermediate-mass star, we increased the stellar energy flux artificially while trying to maintain a structure close to the one given by a 1D stellar model. A parametric study of the flux factor was performed. For the massive star, no such process was necessary. Numerical results were analysed when the system reached the statistical steady state. It was shown that the penetration distance in pressure scaleheights is of the order of unity. The scaling relations between penetration distance, input flux and vertical velocity fluctuations studied by Singh et al. were checked. The anisotropy of the turbulent convection and the diffusion models of the third-order moments representing the non-local transport were also investigated. These models are dramatically affected by the velocity fields and no universal constant parameters seem to exist. The limitations of the numerical results were also discussed.

  2. Downward Causation and the Neurobiology of Free Will

    CERN Document Server

    Murphy, Nancey; O’Connor, Timothy

    2009-01-01

    How is free will possible in the light of the physical and chemical underpinnings of brain activity and recent neurobiological experiments? How can the emergence of complexity in hierarchical systems such as the brain, based at the lower levels in physical interactions, lead to something like genuine free will? The nature of our understanding of free will in the light of present-day neuroscience is becoming increasingly important because of remarkable discoveries on the topic being made by neuroscientists at the present time, on the one hand, and its crucial importance for the way we view ourselves as human beings, on the other. A key tool in understanding how free will may arise in this context is the idea of downward causation in complex systems, happening coterminously with bottom up causation, to form an integral whole. Top-down causation is usually neglected, and is therefore emphasized in the other part of the book’s title. The concept is explored in depth, as are the ethical and legal implications of...

  3. Assesment of longwave radiation effects on air quality modelling in street canyons

    Science.gov (United States)

    Soucasse, L.; Buchan, A.; Pain, C.

    2016-12-01

    Computational Fluid Dynamics is widely used as a predictive tool to evaluate people's exposure to pollutants in urban street canyons. However, in low-wind conditions, flow and pollutant dispersion in the canyons are driven by thermal effects and may be affected by longwave (infrared) radiation due to the absorption and emission of water vapor contained in the air. These effects are mostly ignored in the literature dedicated to air quality modelling at this scale. This study aims at quantifying the uncertainties due to neglecting thermal radiation in air quality models. The Large-Eddy-Simulation of air flow in a single 2D canyon with a heat source on the ground is considered for Rayleigh and Reynolds numbers in the range of [10e8-10e10] and [5.10e3-5.10e4] respectively. The dispersion of a tracer is monitored once the statistically steady regime is reached. Incoming radiation is computed for a mid-latitude summer atmosphere and canyon surfaces are assumed to be black. Water vapour is the only radiating molecule considered and a global model is used to treat the spectral dependancy of its absorption coefficient. Flow and radiation fields are solved in a coupled way using the finite element solvers Fluidity and Fetch which have the capability of adapting their space and angular resolution according to an estimate of the solution error. Results show significant effects of thermal radiation on flow patterns and tracer dispersion. When radiation is taken into account, the air is heated far from the heat source leading to a stronger natural convection flow. The tracer is then dispersed faster out of the canyon potentially decreasing people's exposure to pollution within the street canyon.

  4. Practices and attitudes of doctors and patients to downward referral in Shanghai, China.

    Science.gov (United States)

    Yu, Wenya; Li, Meina; Nong, Xin; Ding, Tao; Ye, Feng; Liu, Jiazhen; Dai, Zhixing; Zhang, Lulu

    2017-04-03

    In China, the rate of downward referral is relatively low, as most people are unwilling to be referred from hospitals to community health systems (CHSs). The aim of this study was to explore the effect of doctors' and patients' practices and attitudes on their willingness for downward referral and the relationship between downward referral and sociodemographic characteristics. Doctors and patients of 13 tertiary hospitals in Shanghai were stratified through random sampling. The questionnaire surveyed their sociodemographic characteristics, attitudes towards CHSs and hospitals, understanding of downward referral, recognition of the community first treatment system, and downward referral practices and willingness. Descriptive statistics, χ 2 test and stepwise logistic regression analysis were employed for statistical analysis. Only 20.8% (161/773) of doctors were willing to accept downward referrals, although this proportion was higher among patients (37.6%, 326/866). Doctors' willingness was influenced by education, understanding of downward referral, and perception of health resources in hospitals. Patients' willingness was influenced by marital status, economic factors and recognition of the community first treatment system. Well-educated doctors who do not consider downward referral would increase their workloads and those with a more comprehensive understanding of hospitals and downward referral process were more likely to make a downward referral decision. Single-injury patients fully recognising the community first treatment system were more willing to accept downward referral. Patients' willingness was significantly increased if downward referral was cost-saving. A better medical insurance system was another key factor for patients to accept downward referral decisions, especially for the floating population. To increase the rate of downward referral, the Chinese government should optimise the current referral system and conduct universal publicity for

  5. Variability In Long-Wave Runup as a Function of Nearshore Bathymetric Features

    Energy Technology Data Exchange (ETDEWEB)

    Dunkin, Lauren McNeill [Texas A & M Univ., College Station, TX (United States)

    2010-05-01

    Beaches and barrier islands are vulnerable to extreme storm events, such as hurricanes, that can cause severe erosion and overwash to the system. Having dunes and a wide beach in front of coastal infrastructure can provide protection during a storm, but the influence that nearshore bathymetric features have in protecting the beach and barrier island system is not completely understood. The spatial variation in nearshore features, such as sand bars and beach cusps, can alter nearshore hydrodynamics, including wave setup and runup. The influence of bathymetric features on long-wave runup can be used in evaluating the vulnerability of coastal regions to erosion and dune overtopping, evaluating the changing morphology, and implementing plans to protect infrastructure. In this thesis, long-wave runup variation due to changing bathymetric features as determined with the numerical model XBeach is quantified (eXtreme Beach behavior model). Wave heights are analyzed to determine the energy through the surfzone. XBeach assumes that coastal erosion at the land-sea interface is dominated by bound long-wave processes. Several hydrodynamic conditions are used to force the numerical model. The XBeach simulation results suggest that bathymetric irregularity induces significant changes in the extreme long-wave runup at the beach and the energy indicator through the surfzone.

  6. Modeled Downward Transport of a Passive Tracer over Western North America during an Asian Dust Event in April 1998.

    Science.gov (United States)

    Hacker, Joshua P.; McKendry, Ian G.; Stull, Roland B.

    2001-09-01

    An intense Gobi Desert dust storm in April 1998 loaded the midtroposphere with dust that was transported across the Pacific to western North America. The Mesoscale Compressible Community (MC2) model was used to investigate mechanisms causing downward transport of the midtropospheric dust and to explain the high concentrations of particulate matter of less than 10-m diameter measured in the coastal urban areas of Washington and southern British Columbia. The MC2 was initialized with a thin, horizontally homogeneous layer of passive tracer centered at 650 hPa for a simulation from 0000 UTC 26 April to 0000 UTC 30 April 1998. Model results were in qualitative agreement with observed spatial and temporal patterns of particulate matter, indicating that it captured the important meteorological processes responsible for the horizontal and vertical transport over the last few days of the dust event. A second simulation was performed without topography to isolate the effects of topography on downward transport.Results show that the dust was advected well east of the North American coast in southwesterly midtropospheric flow, with negligible dust concentration reaching the surface initially. Vertically propagating mountain waves formed during this stage, and differences between downward and upward velocities in these waves could account for a rapid descent of dust to terrain height, where the dust was entrained into the turbulent planetary boundary layer. A deepening outflow (easterly) layer near the surface transported the tracer westward and created a zonal-shear layer that further controlled the tracer advection. Later, the shear layer lifted, leading to a downward hydraulic acceleration along the western slopes, as waves generated in the easterly flow amplified below the shear layer that was just above mountain-crest height. Examination of 10 yr of National Centers for Environmental Prediction-National Center for Atmospheric Research reanalyses suggests that such events

  7. Enhancement of downward-facing saturated boiling heat transfer by the cold spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Sohag, Frauk A.; Beck, Faith R.; Mohanta, Lokanath; Cheung, Fan Bill; Segall, Albert E.; Eden, Timothy J.; Potter, John K. [Pennsylvania State University, University Park (United States)

    2017-02-15

    In-vessel retention by passive external reactor vessel cooling under severe accident conditions is a viable approach for retention of radioactive core melt within the reactor vessel. In this study, a new and versatile coating technique known as 'cold spray' that can readily be applied to operating and advanced reactors was developed to form a microporous coating on the outer surface of a simulated reactor lower head. Quenching experiments were performed under simulated in-vessel retention by passive external reactor vessel cooling conditions using test vessels with and without cold spray coatings. Quantitative measurements show that for all angular locations on the vessel outer surface, the local critical heat flux (CHF) values for the coated vessel were consistently higher than the corresponding CHF values for the bare vessel. However, it was also observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit vary appreciably along the outer surface of the test vessel. Nonetheless, results of this intriguing study clearly show that the use of cold spray coatings could enhance the local CHF limit for downward-facing boiling by > 88%.

  8. Spatio-temporal representativeness of ground-based downward solar radiation measurements

    Science.gov (United States)

    Schwarz, Matthias; Wild, Martin; Folini, Doris

    2017-04-01

    Surface solar radiation (SSR) is most directly observed with ground based pyranometer measurements. Besides measurement uncertainties, which arise from the pyranometer instrument itself, also errors attributed to the limited spatial representativeness of observations from single sites for their large-scale surrounding have to be taken into account when using such measurements for energy balance studies. In this study the spatial representativeness of 157 homogeneous European downward surface solar radiation time series from the Global Energy Balance Archive (GEBA) and the Baseline Surface Radiation Network (BSRN) were examined for the period 1983-2015 by using the high resolution (0.05°) surface solar radiation data set from the Satellite Application Facility on Climate Monitoring (CM-SAF SARAH) as a proxy for the spatiotemporal variability of SSR. By correlating deseasonalized monthly SSR time series form surface observations against single collocated satellite derived SSR time series, a mean spatial correlation pattern was calculated and validated against purely observational based patterns. Generally decreasing correlations with increasing distance from station, with high correlations (R2 = 0.7) in proximity to the observational sites (±0.5°), was found. When correlating surface observations against time series from spatially averaged satellite derived SSR data (and thereby simulating coarser and coarser grids), very high correspondence between sites and the collocated pixels has been found for pixel sizes up to several degrees. Moreover, special focus was put on the quantification of errors which arise in conjunction to spatial sampling when estimating the temporal variability and trends for a larger region from a single surface observation site. For 15-year trends on a 1° grid, errors due to spatial sampling in the order of half of the measurement uncertainty for monthly mean values were found.

  9. BABCOCK–LEIGHTON SOLAR DYNAMO: THE ROLE OF DOWNWARD PUMPING AND THE EQUATORWARD PROPAGATION OF ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Karak, Bidya Binay; Cameron, Robert, E-mail: bkarak@ucar.edu [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-11-20

    The key elements of the Babcock–Leighton dynamos are the generation of poloidal field through decay and the dispersal of tilted bipolar active regions and the generation of toroidal field through the observed differential rotation. These models are traditionally known as flux transport dynamo models as the equatorward propagations of the butterfly wings in these models are produced due to an equatorward flow at the bottom of the convection zone. Here we investigate the role of downward magnetic pumping near the surface using a kinematic Babcock–Leighton model. We find that the pumping causes the poloidal field to become predominately radial in the near-surface shear layer, which allows the negative radial shear to effectively act on the radial field to produce a toroidal field. We observe a clear equatorward migration of the toroidal field at low latitudes as a consequence of the dynamo wave even when there is no meridional flow in the deep convection zone. Both the dynamo wave and the flux transport type solutions are thus able to reproduce some of the observed features of the solar cycle including the 11-year periodicity. The main difference between the two types of solutions is the strength of the Babcock–Leighton source required to produce the dynamo action. A second consequence of the magnetic pumping is that it suppresses the diffusion of fields through the surface, which helps to allow an 11-year cycle at (moderately) larger values of magnetic diffusivity than have previously been used.

  10. BABCOCK–LEIGHTON SOLAR DYNAMO: THE ROLE OF DOWNWARD PUMPING AND THE EQUATORWARD PROPAGATION OF ACTIVITY

    International Nuclear Information System (INIS)

    Karak, Bidya Binay; Cameron, Robert

    2016-01-01

    The key elements of the Babcock–Leighton dynamos are the generation of poloidal field through decay and the dispersal of tilted bipolar active regions and the generation of toroidal field through the observed differential rotation. These models are traditionally known as flux transport dynamo models as the equatorward propagations of the butterfly wings in these models are produced due to an equatorward flow at the bottom of the convection zone. Here we investigate the role of downward magnetic pumping near the surface using a kinematic Babcock–Leighton model. We find that the pumping causes the poloidal field to become predominately radial in the near-surface shear layer, which allows the negative radial shear to effectively act on the radial field to produce a toroidal field. We observe a clear equatorward migration of the toroidal field at low latitudes as a consequence of the dynamo wave even when there is no meridional flow in the deep convection zone. Both the dynamo wave and the flux transport type solutions are thus able to reproduce some of the observed features of the solar cycle including the 11-year periodicity. The main difference between the two types of solutions is the strength of the Babcock–Leighton source required to produce the dynamo action. A second consequence of the magnetic pumping is that it suppresses the diffusion of fields through the surface, which helps to allow an 11-year cycle at (moderately) larger values of magnetic diffusivity than have previously been used.

  11. The measurement of longwave radiation properties upon plastic films used in greenhouses

    International Nuclear Information System (INIS)

    Horiguchi, I.; Tani, H.; Sugaya, H.

    1982-01-01

    Due to the rising cost of heating oils in recent years, the subject of heat conservation on a greenhouse has become more important. In this aspect, the plastic films used for reducing heat losses must have low transmittance property for longwave radiation, also need to have low emissivity. The properties of plastic films which affect on the transfer of energy are important. The paper discusses the measurements of reflectance, transmittance, and emissivity of longwave radiation (thermal radiation) upon various plastic films used for crop protection in agriculture, particularly in a greenhouse. New measuring methods for reflectance and emissivity were presented, and the previous transmittance calculations (Hagiwara and Horiguchi, 1972) were improved by using newly obtained reflectance values. The transmittance values obtained from the present study are about 2-5 percent larger than the values obtained from the previous study. The reason for the discrepancy may be due to the negligence of the reflectance term in the previous calculation. (author)

  12. Large-Amplitude Long-Wave Instability of a Supersonic Shear Layer

    Science.gov (United States)

    Messiter, A. F.

    1995-01-01

    For sufficiently high Mach numbers, small disturbances on a supersonic vortex sheet are known to grow in amplitude because of slow nonlinear wave steepening. Under the same external conditions, linear theory predicts slow growth of long-wave disturbances to a thin supersonic shear layer. An asymptotic formulation is given here which adds nonzero shear-layer thickness to the weakly nonlinear formulation for a vortex sheet. Spatial evolution is considered, for a spatially periodic disturbance having amplitude of the same order, in Reynolds number, as the shear-layer thickness. A quasi-equilibrium inviscid nonlinear critical layer is found, with effects of diffusion and slow growth appearing through nonsecularity condition. Other limiting cases are also considered, in an attempt to determine a relationship between the vortex-sheet limit and the long-wave limit for a thin shear layer; there appear to be three special limits, corresponding to disturbances of different amplitudes at different locations along the shear layer.

  13. Single interval longwave radiation scheme based on the net exchanged rate decomposition with bracketing

    Czech Academy of Sciences Publication Activity Database

    Geleyn, J.- F.; Mašek, Jan; Brožková, Radmila; Kuma, P.; Degrauwe, D.; Hello, G.; Pristov, N.

    2017-01-01

    Roč. 143, č. 704 (2017), s. 1313-1335 ISSN 0035-9009 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : numerical weather prediction * climate models * clouds * parameterization * atmospheres * formulation * absorption * scattering * accurate * database * longwave radiative transfer * broadband approach * idealized optical paths * net exchanged rate decomposition * bracketing * selective intermittency Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 3.444, year: 2016

  14. Photonic antenna enhanced middle wave and longwave infrared focal plane array with low noise and high operating temperature, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Photodetectors and focal plane arrays (FPAs) covering the middle-wave and longwave infrared (MWIR/LWIR) are of great importance in numerous NASA applications,...

  15. Long-wave plasma radiofrequency ablation for treatment of xanthelasma palpebrarum.

    Science.gov (United States)

    Baroni, Adone

    2018-03-01

    Xanthelasma palpebrarum is the most common type of xanthoma affecting the eyelids. It is characterized by asymptomatic soft yellowish macules, papules, or plaques over the upper and lower eyelids. Many treatments are available for management of xanthelasma palpebrarum, the most commonly used include surgical excision, ablative CO 2 or erbium lasers, nonablative Q-switched Nd:YAG laser, trichloroacetic acid peeling, and radiofrequency ablation. This study aims to evaluate the effectiveness of RF ablation in the treatment of xanthelasma palpebrarum, with D.A.S. Medical portable device (Technolux, Italia), a radiofrequency tool working with long-wave plasma energy and without anesthesia. Twenty patients, 15 female and 5 male, affected by xanthelasma palpebrarum, were enrolled for long-wave plasma radiofrequency ablation treatment. The treatment consisted of 3/4 sessions that were carried out at intervals of 30 days. Treatments were well tolerated by all patients with no adverse effects and optimal aesthetic results. The procedure is very fast and can be performed without anesthesia because of the low and tolerable pain stimulation. Long-wave plasma radiofrequency ablation is an effective option for treatment of xanthelasma palpebrarum and adds an additional tool to the increasing list of medical devices for aesthetic treatments. © 2018 Wiley Periodicals, Inc.

  16. Technical considerations for designing low-cost, long-wave infrared objectives

    Science.gov (United States)

    Desroches, Gerard; Dalzell, Kristy; Robitaille, Blaise

    2014-06-01

    With the growth of uncooled infrared imaging in the consumer market, the balance between cost implications and performance criteria in the objective lens must be examined carefully. The increased availability of consumer-grade, long-wave infrared cameras is related to a decrease in military usage but it is also due to the decreasing costs of the cameras themselves. This has also driven up demand for low-cost, long-wave objectives that can resolve smaller pixels while maintaining high performance. Smaller pixels are traditionally associated with high cost objectives because of higher resolution requirements but, with careful consideration of all the requirements and proper selection of materials, costs can be moderated. This paper examines the cost/performance trade-off implications associated with optical and mechanical requirements of long-wave infrared objectives. Optical performance, f-number, field of view, distortion, focus range and thermal range all affect the cost of the objective. Because raw lens material cost is often the most expensive item in the construction, selection of the material as well as the shape of the lens while maintaining acceptable performance and cost targets were explored. As a result of these considerations, a low-cost, lightweight, well-performing objective was successfully designed, manufactured and tested.

  17. Measurement of pool boiling CHF for SUS 304 and SA 508 flat plate under downward-facing and atmospheric conditions

    International Nuclear Information System (INIS)

    Kam, Dong Hoon; Park, Hae Min; Choi, Young Jae; Jeong, Yong Hoon

    2015-01-01

    Heat transfer performance of downward-facing conditions are important especially in severe accident mitigation strategy (IVR-ERVC and Core-catcher). Heat transfer limit, in other word, critical heat flux (CHF) is important value in this basis to guarantee the integrity of the system. For the application point of view in nuclear power plant, carbon steel surface should also be considered since reactor pressure vessel (RPV) in IVR-ERVC strategy consists of carbon steel, and core-catcher in EU-APR1400 is also composed of carbon steel. In this perspective, carbon steel surface was used in previous studies. In this study, CHF of both stainless steel and carbon steel material were measured under pool boiling condition with various inclination angles and dimensions. There was a width effect as angle increases, but it disappeared as approached to horizontally downward condition. Besides, there was almost no length effect for both of the width since the size of coalesced bubble was far smaller than the length of short test section (100 mm). SA 508 showed enhanced results at high angles for 40 mm-width case even though no oxidation occurred on the surface during the experiments

  18. Measurement of pool boiling CHF for SUS 304 and SA 508 flat plate under downward-facing and atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kam, Dong Hoon; Park, Hae Min; Choi, Young Jae; Jeong, Yong Hoon [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    Heat transfer performance of downward-facing conditions are important especially in severe accident mitigation strategy (IVR-ERVC and Core-catcher). Heat transfer limit, in other word, critical heat flux (CHF) is important value in this basis to guarantee the integrity of the system. For the application point of view in nuclear power plant, carbon steel surface should also be considered since reactor pressure vessel (RPV) in IVR-ERVC strategy consists of carbon steel, and core-catcher in EU-APR1400 is also composed of carbon steel. In this perspective, carbon steel surface was used in previous studies. In this study, CHF of both stainless steel and carbon steel material were measured under pool boiling condition with various inclination angles and dimensions. There was a width effect as angle increases, but it disappeared as approached to horizontally downward condition. Besides, there was almost no length effect for both of the width since the size of coalesced bubble was far smaller than the length of short test section (100 mm). SA 508 showed enhanced results at high angles for 40 mm-width case even though no oxidation occurred on the surface during the experiments.

  19. Tornado frequency in the USA - meteorological and non-meteorological factors of a downward trend

    Directory of Open Access Journals (Sweden)

    Mihajlović Jovan

    2015-01-01

    Full Text Available Citing numerical simulations, climate alarmists believe that global warming will lead to more frequent and more intensive tornadoes. Considering temperature increase data in the contiguous USA, this study has investigated the trend of strong tornadoes in F3+ category in the 1954-2012 period. Statistically significant decrease of tornadoes per year at an average rate of 0.44 has been recorded, that is, 4.4 tornadoes per decade. Tornado increase has been recorded with F0 and F1 categories and the cause of this increase lies in meteorological and non-meteorological factors. By using upper and lower standard deviation values, the stages of tornado activity have been singled out. The 1957-1974 period may be considered as an active stage and the 1978-2009 period as an inactive stage. Upward trend of air temperature increase does not correspond with the downward trend of the number of F3+ tornado category, while the correlation coefficient between these two variables is R = −0.14. This fact does not correspond with the simulation results and output data of various numerical models anticipating an increase in the number and intensity of tornado events in the conditions of surface air temperature growth.

  20. Experimental study of natural convection heat transfer from an isothermal combined geometry (downward cone- cylinder)

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, A. [Yazd Univ., Yazd (Iran, Islamic Republic of). Dept. of Mechanical Engineering; Goharkhah, M.; Ashjaee, M. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Mechanical Engineering

    2009-07-01

    Laminar free convection heat transfer from an isothermal combined geometry which consists of a downward cone attached to a vertical cylinder was studied. In particular, a Mach-Zehnder interferometer was used to determine the change in local and average heat transfer coefficients on the surface of an isothermal combined geometry for different vertex angles. The effect of the vertex angle on heat transfer was also investigated by keeping the height of the cylinder and slant length of the cone constant for all objects. The experimental data showed that the local heat transfer coefficient on the conical part increased in the vicinity of the cylinder and cone intersection. The distance between the point of minimum heat transfer coefficient on the cone and vertex of the cone decreased as the vertex angle increased. The maximum average Nusselt number for a constant Rayleigh number was obtained for the geometry with the smallest vertex angle. For all objects, the average Nusselt number increased with an increase in the Rayleigh number. An experiment was carried out on a vertical isothermal cylinder of circular cross section in order to validate the experimental approach. An analytical solution was found to be in good agreement with experimental results. 31 refs., 9 figs.

  1. Urban surface energy fluxes based on remotely-sensed data and micrometeorological measurements over the Kansai area, Japan

    Science.gov (United States)

    Sukeyasu, T.; Ueyama, M.; Ando, T.; Kosugi, Y.; Kominami, Y.

    2017-12-01

    The urban heat island is associated with land cover changes and increases in anthropogenic heat fluxes. Clear understanding of the surface energy budget at urban area is the most important for evaluating the urban heat island. In this study, we develop a model based on remotely-sensed data for the Kansai area in Japan and clarify temporal transitions and spatial distributions of the surface energy flux from 2000 to 2016. The model calculated the surface energy fluxes based on various satellite and GIS products. The model used land surface temperature, surface emissivity, air temperature, albedo, downward shortwave radiation and land cover/use type from the moderate resolution imaging spectroradiometer (MODIS) under cloud free skies from 2000 to 2016 over the Kansai area in Japan (34 to 35 ° N, 135 to 136 ° E). Net radiation was estimated by a radiation budget of upward/downward shortwave and longwave radiation. Sensible heat flux was estimated by a bulk aerodynamic method. Anthropogenic heat flux was estimated by the inventory data. Latent heat flux was examined with residues of the energy budget and parameterization of bulk transfer coefficients. We validated the model using observed fluxes from five eddy-covariance measurement sites: three urban sites and two forested sites. The estimated net radiation roughly agreed with the observations, but the sensible heat flux were underestimated. Based on the modeled spatial distributions of the fluxes, the daytime net radiation in the forested area was larger than those in the urban area, owing to higher albedo and land surface temperatures in the urban area than the forested area. The estimated anthropogenic heat flux was high in the summer and winter periods due to increases in energy-requirements.

  2. New sea surface salinity product in the tropical Indian Ocean estimated from outgoing longwave radiation

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, B.; Murty, V.S.N.; O'Brien, J.J.

    by the NOAA-CIRES Climate Diagnostics Center, Boulder, Colorado from their web'-site at http://www.cdc.noaa.gov/. We thank Simon Josey for making available the SOC E-P data. Dr. Pingping Xie, Climate Prediction Center kindly provided CMAP rainfall data...

  3. Dispersion relation for long-wave neutrons and the possibility of its precise experimental verification

    International Nuclear Information System (INIS)

    Frank, A.I.; Nosov, V.G.

    1995-01-01

    Modern theoretical concepts concerning the dispersion relation for slow neutrons in matter are considered. The generally accepted optical-potential model is apparently not quite accurate and should be supplemented with some small corrections in the energy range attainable in experiments. For ultracold neutrons, these corrections are related to the proximity of the applicability boundary of the theory; for cold neutrons, these corrections are due to correlations in the positions of scatters. The accuracy of existing experiments is insufficient for confirmation or refutation these conclusions. A precision experiment is proposed to verify the dispersion relation for long-wave neutrons. 30 refs., 3 figs

  4. The behaviour of hydrogen-like atoms in an intense long-wave field

    International Nuclear Information System (INIS)

    Brodsky, A.M.

    1979-01-01

    The equations, which permit the calculation by means of regular operations of multiphoton photoionisation cross sections and the dynamic polarisabilities in an intense classical long-wave electromagnetic field, are considered for a hydrogen atom. The calculations have been performed for a circularly polarised field. A quantitative expression has been derived for the Lamb shift analogue, which can be verified experimentally. Within the framework of the problem the interaction at small distances is self-compensated and reduced to a constant potential. This conclusion is of general interest for the theory of strong interactions. (author)

  5. Achromatic triplet and athermalized lens assembly for both midwave and longwave infrared spectra

    Science.gov (United States)

    Kuo, Chih-Wei

    2014-02-01

    Analytic solutions for finding the achromatic triplet in the midwave and longwave infrared spectra simultaneously are explored. The relationship between the combination of promising refractive materials and the system's optical power is also formulated. The principles for stabilizing the effective focal length of an air-spaced lens group with respect to temperature are explored, and the thermal properties of the optical component and mechanical elements mutually counterbalanced. An optical design based on these achromatic and athermal theories is demonstrated, and the image quality of the lens assembly seems to approach the diffractive limitation.

  6. Analysis of steady state and transient two-phase flows in downwardly inclined lines

    International Nuclear Information System (INIS)

    Crawford, T.J.

    1983-01-01

    A study of steady-state and transient two-phase flows in downwardly inclined lines is described. Steady-state flow patterns maps are presented using Freon-113 as the working fluid to provide new high density vapors. These flow maps with high density vapor serve to significantly extend the investigations of steady-state downward two-phase flow patterns. Physical models developed which successfully predicted the onset or location of various flow pattern transitions. A new simplified criterion that would be useful to designers and experimenters is offered for the onset of dispersed flow. A new empirical holdup correlation and a new bubble diameter/flow rate correlation are also proposed. Flow transients in vertical downward lines were studied to investigate the possible formation of intermediate or spurious flow patterns that would not be seen at steady-state conditions. Void fraction behavior during the transients was modeled by using the dynamic slip equation from the transient analysis code RETRAN. Physical models of interfacial area were developed and compared with models and data from literature. There was satisfactory agreement between the models of the present study and the literature models and data. The concentration parameter of the drift flux model was evaluated for vertical downward flow. These new values of the flow dependent parameter were different from those previously proposed in the literature for use in upward flows, and made the drift flux model suitable for use in upward or downward flow lines

  7. New data on two-phase water-air hydrodynamics in vertical upward and downward tubes

    Energy Technology Data Exchange (ETDEWEB)

    Lau, V [Atomic Energy of Canada Ltd., Saskatoon, SK (Canada); Rezkallah, K S [Saskatchewan Univ., Saskatoon (Canada). Mechanical Engineering Dept.

    1996-12-31

    The three key parameters involved in the analysis of the hydrodynamic characteristics of a two-phase system (i.e. pressure drop, void fraction, and flow pattern associated with the flow) are taken in vertical upward and downward tubes, using water-air mixture at atmospheric pressure. The acquired data set covers a wide range of liquid and gas flow rates, as well as void fractions. Using the acquired data set, two sets of flow pattern maps, for both upward and downward flows, are developed in the present study. Furthermore, a set of correlations for predicting the frictional pressure drop in both upward and downward flow were also developed. (author). 16 refs., 13 figs.

  8. Numerical Solutions of the Mean-Value Theorem: New Methods for Downward Continuation of Potential Fields

    Science.gov (United States)

    Zhang, Chong; Lü, Qingtian; Yan, Jiayong; Qi, Guang

    2018-04-01

    Downward continuation can enhance small-scale sources and improve resolution. Nevertheless, the common methods have disadvantages in obtaining optimal results because of divergence and instability. We derive the mean-value theorem for potential fields, which could be the theoretical basis of some data processing and interpretation. Based on numerical solutions of the mean-value theorem, we present the convergent and stable downward continuation methods by using the first-order vertical derivatives and their upward continuation. By applying one of our methods to both the synthetic and real cases, we show that our method is stable, convergent and accurate. Meanwhile, compared with the fast Fourier transform Taylor series method and the integrated second vertical derivative Taylor series method, our process has very little boundary effect and is still stable in noise. We find that the characters of the fading anomalies emerge properly in our downward continuation with respect to the original fields at the lower heights.

  9. Experimental study on downward two-phase flow in narrow rectangular channel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T.H.; Jeong, J.H. [Pusan National Univ., Busan (Korea, Republic of)

    2014-07-01

    Adiabatic vertical two-phase flow of air and water through narrow rectangular channels was investigated. This study involved the observation of flow using a high speed camera and flow regimes were determined by image processing program using a MATLAB. The flows regimes in channel with downward flow are similar to those found by previous studies with upward flow. The flow regimes in downward flow at low liquid velocity are different from the previous studies in upward flow. The flow regimes can be classified into bubbly, cap-bubbly, slug and churn flow. (author)

  10. Evaluation and Comparison of the Processing Methods of Airborne Gravimetry Concerning the Errors Effects on Downward Continuation Results: Case Studies in Louisiana (USA) and the Tibetan Plateau (China).

    Science.gov (United States)

    Zhao, Qilong; Strykowski, Gabriel; Li, Jiancheng; Pan, Xiong; Xu, Xinyu

    2017-05-25

    Gravity data gaps in mountainous areas are nowadays often filled in with the data from airborne gravity surveys. Because of the errors caused by the airborne gravimeter sensors, and because of rough flight conditions, such errors cannot be completely eliminated. The precision of the gravity disturbances generated by the airborne gravimetry is around 3-5 mgal. A major obstacle in using airborne gravimetry are the errors caused by the downward continuation. In order to improve the results the external high-accuracy gravity information e.g., from the surface data can be used for high frequency correction, while satellite information can be applying for low frequency correction. Surface data may be used to reduce the systematic errors, while regularization methods can reduce the random errors in downward continuation. Airborne gravity surveys are sometimes conducted in mountainous areas and the most extreme area of the world for this type of survey is the Tibetan Plateau. Since there are no high-accuracy surface gravity data available for this area, the above error minimization method involving the external gravity data cannot be used. We propose a semi-parametric downward continuation method in combination with regularization to suppress the systematic error effect and the random error effect in the Tibetan Plateau; i.e., without the use of the external high-accuracy gravity data. We use a Louisiana airborne gravity dataset from the USA National Oceanic and Atmospheric Administration (NOAA) to demonstrate that the new method works effectively. Furthermore, and for the Tibetan Plateau we show that the numerical experiment is also successfully conducted using the synthetic Earth Gravitational Model 2008 (EGM08)-derived gravity data contaminated with the synthetic errors. The estimated systematic errors generated by the method are close to the simulated values. In addition, we study the relationship between the downward continuation altitudes and the error effect. The

  11. Evaluation and Comparison of the Processing Methods of Airborne Gravimetry Concerning the Errors Effects on Downward Continuation Results: Case Studies in Louisiana (USA) and the Tibetan Plateau (China)

    Science.gov (United States)

    Zhao, Q.

    2017-12-01

    Gravity data gaps in mountainous areas are nowadays often filled in with the data from airborne gravity surveys. Because of the errors caused by the airborne gravimeter sensors, and because of rough flight conditions, such errors cannot be completely eliminated. The precision of the gravity disturbances generated by the airborne gravimetry is around 3-5 mgal. A major obstacle in using airborne gravimetry are the errors caused by the downward continuation. In order to improve the results the external high-accuracy gravity information e.g., from the surface data can be used for high frequency correction, while satellite information can be applying for low frequency correction. Surface data may be used to reduce the systematic errors, while regularization methods can reduce the random errors in downward continuation. Airborne gravity surveys are sometimes conducted in mountainous areas and the most extreme area of the world for this type of survey is the Tibetan Plateau. Since there are no high-accuracy surface gravity data available for this area, the above error minimization method involving the external gravity data cannot be used. We propose a semi-parametric downward continuation method in combination with regularization to suppress the systematic error effect and the random error effect in the Tibetan Plateau; i.e., without the use of the external high-accuracy gravity data. We use a Louisiana airborne gravity dataset from the USA National Oceanic and Atmospheric Administration (NOAA) to demonstrate that the new method works effectively. Furthermore, and for the Tibetan Plateau we show that the numerical experiment is also successfully conducted using the synthetic Earth Gravitational Model 2008 (EGM08)-derived gravity data contaminated with the synthetic errors. The estimated systematic errors generated by the method are close to the simulated values. In addition, we study the relationship between the downward continuation altitudes and the error effect. The

  12. Doing worse, but feeling happy : Social comparison and identification in response to upward and downward targets

    NARCIS (Netherlands)

    Groothof, H.; Siero, F.W.; Buunk, Abraham (Bram)

    2007-01-01

    We investigated people's responses to exposure to downward and upward targets. In Study 1, among 197 participants, it was predicted and found that such exposure led to a contrast effect on self-evaluation, and to an assimilation effect on affect. In Study 2, among 148 participants, it was predicted

  13. Feeling bad, but satisfied : the effects of upward and downward comparison upon mood and marital satisfaction

    NARCIS (Netherlands)

    Buunk, B.P.; Ybema, J.F.

    2003-01-01

    In a sample of 135 women from rural areas, the effects of social comparison with the marriage of another woman upon mood, identification and relationship evaluation were examined. Upward targets evoked a more positive mood, and a less negative mood than downward targets, while, in contrast, the

  14. Generalized intermediate long-wave hierarchy in zero-curvature representation with noncommutative spectral parameter

    Science.gov (United States)

    Degasperis, A.; Lebedev, D.; Olshanetsky, M.; Pakuliak, S.; Perelomov, A.; Santini, P. M.

    1992-11-01

    The simplest generalization of the intermediate long-wave hierarchy (ILW) is considered to show how to extend the Zakharov-Shabat dressing method to nonlocal, i.e., integro-partial differential, equations. The purpose is to give a procedure of constructing the zero-curvature representation of this class of equations. This result obtains by combining the Drinfeld-Sokolov formalism together with the introduction of an operator-valued spectral parameter, namely, a spectral parameter that does not commute with the space variable x. This extension provides a connection between the ILWk hierarchy and the Saveliev-Vershik continuum graded Lie algebras. In the case of ILW2 the Fairlie-Zachos sinh-algebra was found.

  15. Biologic changes due to long-wave ultraviolet irradiation on human skin: ultrastructural study

    International Nuclear Information System (INIS)

    Kumakiri, M.; Hashimoto, K.; Willis, I.

    1977-01-01

    Alteration of the skin induced by single and repeated long-wave ultraviolet (UVA) exposures was studied. Following a single exposure to relatively large doses of UVA, pronounced dermal damage was observed. In the papillary dermis, superficial dermal vessels showed widely open endothelial gaps and extravasation of blood cells. Marked changes of fibroblasts were also seen in the superficial dermis. In the reticular dermis, extravascular fibrin deposition was seen. After repeated exposures to UVA the formation of cross-banded filamentous aggregations (''Zebra bodies'') was observed in the superficial and reticular dermis. These were often found in amorphous masses surrounding the blood vessels. These striking dermal alterations were absent in skin irradiated by solar stimulating radiation and in control skin. Dyskeratotic ''sunburn cells'' were occasionally seen in the epidermis after single as well as repeated exposures to UVA. The number of these cells was less than that seen after a single exposure to solar simulating radiation

  16. Improved Estimates of Clear Sky Longwave Flux and Application to the Tropical Greenhouse Effect

    Science.gov (United States)

    Collins, W. D.

    1997-01-01

    The first objective of this investigation is to eliminate the clear-sky offset introduced by the scene-identification procedures developed for the Earth Radiation Budget Experiment (ERBE). Estimates of this systematic bias range from 10 to as high as 30 W/sq m. The initial version of the ScaRaB data is being processed with the original ERBE algorithm. Since the ERBE procedure for scene identification is based upon zonal flux averages, clear scenes with longwave emission well below the zonal mean value are mistakenly classified as cloudy. The erroneous classification is more frequent in regions with deep convection and enhanced mid- and upper-tropospheric humidity. We will develop scene identification parameters with zonal and/or time dependence to reduce or eliminate the bias in the clear- sky data. The modified scene identification procedure could be used for the ScaRaB-specific version of the Earth-radiation products. The second objective is to investigate changes in the clear-sky Outgoing Longwave Radiation (OLR) associated with decadal variations in the tropical and subtropical climate. There is considerable evidence for a shift in the climate state starting in approximately 1977. The shift is accompanied by higher SSTs in the equatorial Pacific, increased tropical convection, and higher values of atmospheric humidity. Other evidence indicates that the humidity in the tropical troposphere has been steadily increasing over the last 30 years. It is not known whether the atmospheric greenhouse effect has increased during this period in response to these changes in SST and precipitable water. We will investigate the decadal-scale fluctuations in the greenhouse effect using Nimbus-7, ERBE, and ScaRaB measurements spaning 1979 to the present. The data from the different satellites will be intercalibrated by comparison with model calculations based upon ship radiosonde observations. The fluxes calculated from the radiation model will also be used for validation of the

  17. Ground-Based Observations of Terrestrial Gamma Ray Flashes Associated with Downward-Directed Lightning Leaders

    Science.gov (United States)

    Belz, J.; Abbasi, R.; Krehbiel, P. R.; LeVon, R.; Remington, J.; Rison, W.; Thomas, R. J.

    2017-12-01

    Terrestrial Gamma Flashes (TGFs) have been observed in satellite-borne gamma ray detectors for several decades, starting with the BATSE instrument on the Compton Gamma-Ray observatory in 1994. TGFs consist of bursts of upwards of 1018 primary gamma rays, with a duration of up to a few milliseconds, originating in the Earth's atmosphere. More recent observations have shown that satellite-observed TGFs are generated in upward-propagating negative leaders of intracloud lightning, suggesting that they may be sensitive to the processes responsible for the initial lightning breakdown. Here, we present the first evidence that TGFs are also produced at the beginning of negative cloud-to-ground flashes, and that they may provide a new window through which ground-based observatories may contribute to understanding the breakdown process. The Telescope Array Surface Detector (TASD) is a 700 square kilometer cosmic ray observatory, an array of 507 3m2 scintillators on a 1.2 km grid. The array is triggered and read out when at least three adjacent detectors observe activity within an 8 μs window. Following the observation of bursts of anomalous TASD triggers, lasting a few hundred microseconds and correlated with local lightning activity, a Lightning Mapping Array (LMA) and slow electric field antenna were installed at the TASD site in order to study the effect. From data obtained between 2014 and 2016, correlated observations were obtained for ten -CG flashes. In 9 out of 10 cases, bursts of up to five anomalous triggers were detected during the first ms of the flash, as negative breakdown was descending into lower positive storm charge. The triggers occurred when the LMA-detected VHF radiation sources were at altitudes between 1.5 to 4.5 km AGL. The tenth flash was initiated by an unusually energetic leader that reached the ground in 2.5 ms and produced increasingly powerful triggers down to about 500 m AGL. While the TASD is not optimized for individual gamma ray detection

  18. Inlet effects on vertical-downward air–water two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Shouxu; Mena, Daniel; Kim, Seungjin, E-mail: skim@psu.edu

    2017-02-15

    Highlights: • Inlet effects on two-phase flow parameters in vertical-downward flow are studied. • Flow regimes in the vertical-downward two-phase flow are defined. • Vertical-downward flow regime maps for three inlet configurations are developed. • Frictional pressure loss analysis for three different inlets is performed. • Database of local two-phase flow parameters for each inlet configuration. - Abstract: This paper focuses on investigating the geometric effects of inlets on global and local two-phase flow parameters in vertical-downward air–water two-phase flow. Flow visualization, frictional pressure loss analysis, and local experiments are performed in a test facility constructed from 50.8 mm inner diameter acrylic pipes. Three types of inlets of interest are studied: (1) two-phase flow injector without a flow straightener (Type A), (2) two-phase flow injector with a flow straightener (Type B), and (3) injection through a horizontal-to-vertical-downward 90° vertical elbow (Type C). A detailed flow visualization study is performed to characterize flow regimes including bubbly, slug, churn-turbulent, and annular flow. Flow regime maps for each inlet are developed and compared to identify the effects of each inlet. Frictional pressure loss analysis shows that the Lockhart–Martinelli method is capable of correlating the frictional loss data acquired for Type B and Type C inlets with a coefficient value of C = 25, but additional data may be needed to model the Type A inlet. Local two-phase flow parameters measured by a four-sensor conductivity probe in four bubbly and near bubbly flow conditions are analyzed. It is observed that vertical-downward two-phase flow has a characteristic center-peaked void profile as opposed to a wall-peaked profile as seen in vertical-upward flow. Furthermore, it is shown that the Type A inlet results in the most pronounced center-peaked void fraction profile, due to the coring phenomenon. Type B and Type C inlets

  19. Measurement of the rate of droplet deposition in vertical upward and downward annular flows

    International Nuclear Information System (INIS)

    Murakami, Toshihiro; Okawa, Tomio; Takei, Rei

    2008-01-01

    The deposition rate of droplets was measured for vertical annular two-phase flows in a small diameter tube by means of the double film extraction technique. The test section was a round tube of 5 mm in inside diameter, air and water were used as test fluids, and the flow direction was set to upward and downward; the system pressure and the flow rates of gas and liquid phases were changed parametrically. If the droplet velocity relative to the continuous gas phase is in the equilibrium state, the shear induced lift force acting on droplets is directed toward the tube centerline in upflow while toward the tube wall in downflow. Particular attention was therefore paid to the effect of flow direction. It was shown experimentally that the deposition rate of droplets in downward flow is greater than that in upward flow. The difference in the measured deposition rate may be attributed to the direction of lift force acting on droplets. (author)

  20. Downward Slope Driving Control for Electric Powered Wheelchair Based on Capacitor Regenerative Brake

    Science.gov (United States)

    Seki, Hirokazu; Takahashi, Yoshiaki

    This paper describes a novel capacitor regenerative braking control scheme of electric powered wheelchairs for efficient driving on downward slopes. An electric powered wheelchair, which generates the driving force by electric motors, is expected to be widely used as a mobility support system for elderly people and disabled people; however the energy efficiency has to be further improved because it is driven only by battery energy. This study proposes a capacitor regenerative braking circuit and two types of velocity control schemes with variable duty ratio. The proposed regenerative braking circuit is based on the step-up/down circuit with additional resistance and connects right and left motors in series in order to obtain a larger braking power. Some driving experiments on a practical downward slope show the effectiveness of the proposed control system.

  1. Dispersion of Exhalation Pollutants in a Two-bed Hospital Ward with a Downward Ventilation System

    DEFF Research Database (Denmark)

    Qian, Hua; Nielsen, Peter V.; Hyldgård, Carl-Erik

    2006-01-01

    The Centers for Disease Control and Prevention has recommended the use of downward ventilation systems in isolation rooms to reduce the risk of cross-infection from airborne transmissible diseases. The expected airflow pattern of a downward ventilation design would supply cooler and slightly...... to investigate the airflow pattern and pollutant dispersion in the test ward. Based on both experimental and numerical results, the laminar airflow pattern was shown to be impossible to achieve due to turbulent flow mixing and flow entrainment into the supply air stream. The thermal plumes produced above people...... were found to induce flow mixing. We also studied the effects of the locations of the supply and extraction openings on both the flow pattern and pollutant exposure level in the occupied zone. A number of practical recommendations are suggested....

  2. An Experimental Study on the Onset of Nucleate Boiling in Narrow Rectangular Channels for Downward Flow

    International Nuclear Information System (INIS)

    Song, Jung-Hyun; Lee, Juhyung; Jeong, Yong Hoon; Chang, Soon Heung

    2014-01-01

    As the research reactors operates with downward flow, they have some advantages; downward flow can reduce the radioisotopes in the upper part of research reactor and simplify the locking mechanism as countervailing the buoyancy force on the nuclear fuel. However, as the research reactor operates under the low pressure condition, the premature critical heat flux (CHF) can occur during the onset of flow instability (OFI) according to circumstances as the pressure fluctuates significantly. For that reason, it is important to know and set the margin for the onset of nucleate boiling (ONB) which is the preceding phenomena of OFI and CHF to predict and handle with OFI. In addition, research reactor is the nuclear reactor serves neutron source for many research fields such as neutron scattering, non-destructive testing, radioisotope treatment and so on, it is important to avoid ONB to get stable neutron source. IAEA also recommends for research reactors to have enough ONB margin to maintain the normal operation state in 'IAEA-TECDOC-233' (1980). Though the ONB in research reactor is emphasized for these reasons, there isn't sufficient ONB data under downward flow condition and no ONB prediction correlation for downward flow as well. In addition, in many researches; Mosyak et al., Hapke et al., Wu et al. and Hong et al., the existing ONB correlations are not suitable for narrow rectangular channel. In the present work, not only a new ONB prediction correlation would be developed, but also comparison between new correlation with several ONB correlations would be shown. In this paper, ONB data would be analyzed to develop new ONB prediction correlation

  3. Vertical downward subcooled bubbly flow modelling with RELAP5/MOD3.2.2 gamma

    International Nuclear Information System (INIS)

    Ristevski, R.; Parzer, I.; Markov, Z.

    2000-01-01

    The presented paper will consider the correlation for void fraction distribution in the subcooled boiling flow regime of downward liquid flow at low velocities. More specifically, it will focus on the choice of the most appropriate heat and mass transfer correlation. The experimental findings and theoretical consideration of these processes and phenomena will be compared with RELAP5/MOD3.2.2 Gamma predictions. (author)

  4. Fixing the Phillips curve: The case of downward nominal wage rigidity in the US

    OpenAIRE

    Reitz, Stefan; Slopek, Ulf D.

    2012-01-01

    Whereas microeconomic studies point to pronounced downward rigidity of nominal wages in the US economy, the standard Phillips curve neglects such a feature. Using a stochastic frontier model we find macroeconomic evidence of a strictly nonnegative error in an otherwise standard Phillips curve in post-war data on the US nonfinancial corporate sector. This error depends on growth in the profit ratio, output, and trend productivity, which should all determine the flexibility of wage adjustments....

  5. Downward continuation of airborne gravity data by means of the change of boundary approach

    Science.gov (United States)

    Mansi, A. H.; Capponi, M.; Sampietro, D.

    2018-03-01

    Within the modelling of gravity data, a common practice is the upward/downward continuation of the signal, i.e. the process of continuing the gravitational signal in the vertical direction away or closer to the sources, respectively. The gravity field, being a potential field, satisfies the Laplace's equation outside the masses and this means that it allows to unambiguously perform this analytical continuation only in a source-free domain. The analytical continuation problem has been solved both in the space and spectral domains by exploiting different algorithms. As well known, the downward continuation operator, differently from the upward one, is an unstable operator, due to its spectral characteristics similar to those of a high-pass filter, and several regularization methods have been proposed in order to stabilize it. In this work, an iterative procedure to downward/upward continue the gravity field observations, acquired at different altitudes, is proposed. This methodology is based on the change of boundary principle and it has been expressively thought for aerogravimetric observations for geophysical exploration purposes. Within this field of application, usually several simplifications can be applied, basically due to the specific characteristics of the airborne surveys which are usually flown at almost constant altitude as close as possible to the terrain. For instance, these characteristics, as shown in the present work, allow to perform the downward continuation without the need of any regularization. The goodness of the proposed methodology has been evaluated by means of a numerical test on real data, acquired in the South of Australia. The test shows that it is possible to move the aerogravimetric data, acquired along tracks with a maximum height difference of about 250 m, with accuracies of the order of 10^{-3} mGal.

  6. Iterative Spherical Downward Continuation Applied to Magnetic and Gravitational Data from Satellite

    Czech Academy of Sciences Publication Activity Database

    Sebera, J.; Šprlák, M.; Novák, P.; Bezděk, Aleš; Valko, M.

    2014-01-01

    Roč. 35, č. 4 (2014), s. 941-958 ISSN 0169-3298 R&D Projects: GA MŠk LH13071 Grant - others:ESA(XE) AO/1-6367/10/NL/AF Institutional support: RVO:67985815 Keywords : downward continuation * Earth's gravitational and magnetic field * poisson integral equation Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 3.447, year: 2014

  7. Optical progression characteristics of an interesting natural downward bipolar lightning flash

    Science.gov (United States)

    Chen, Luwen; Lu, Weitao; Zhang, Yijun; Wang, Daohong

    2015-01-01

    high-speed cameras, Lightning Attachment Process Observation Systems, and fast and slow electrical antennas, we documented a downward bipolar lightning flash that contained one first positive stroke with a peak current of 142 kA and five subsequent negative strokes hitting on a 90 m tall structure on 29 July 2010 in Guangzhou City, China. All the six strokes propagated along the same viewed channel established by the first positive return stroke. The leader which preceded the positive return stroke propagated downward without any branches at a two-dimensional (2-D) speed of 2.5 × 106 m/s. An upward connecting leader with a length of about 80 m was observed in response to the downward positive leader. The 10-90% risetimes of the return strokes' optical pulses ranged from 2.2 µs to 3.2 µs, while the widths from the 10% wavefront to the 50% wave tail ranged from 56.5 µs to 83.1 µs, and the half peak widths ranged from 53.4 µs to 81.6 µs. All the return strokes exhibited similar speeds, ranging from 1.0 × 108 m/s to 1.3 × 108 m/s. Each of the return strokes was followed by a continuing current stage (CC). The first positive stroke CC lasted more than 150 ms, much larger than all the subsequent negative stroke CC, ranging from 13 ms to 70 ms.

  8. Observations of Magnetosphere-Ionosphere Coupling Processes in Jupiter's Downward Auroral Current Region

    Science.gov (United States)

    Clark, G. B.; Mauk, B.; Allegrini, F.; Bagenal, F.; Bolton, S. J.; Bunce, E. J.; Connerney, J. E. P.; Ebert, R. W.; Gershman, D. J.; Gladstone, R.; Haggerty, D. K.; Hospodarsky, G. B.; Kotsiaros, S.; Kollmann, P.; Kurth, W. S.; Levin, S.; McComas, D. J.; Paranicas, C.; Rymer, A. M.; Saur, J.; Szalay, J. R.; Tetrick, S.; Valek, P. W.

    2017-12-01

    Our view and understanding of Jupiter's auroral regions are ever-changing as Juno continues to map out this region with every auroral pass. For example, since last year's Fall AGU and the release of publications regarding the first perijove orbit, the Juno particles and fields teams have found direct evidence of parallel potential drops in addition to the stochastic broad energy distributions associated with the downward current auroral acceleration region. In this region, which appears to exist in an altitude range of 1.5-3 Jovian radii, the potential drops can reach as high as several megavolts. Associated with these potentials are anti-planetward electron angle beams, energetic ion conics and precipitating protons, oxygen and sulfur. Sometimes the potentials within the downward current region are structured such that they look like the inverted-V type distributions typically found in Earth's upward current region. This is true for both the ion and electron energy distributions. Other times, the parallel potentials appear to be intermittent or spatially structured in a way such that they do not look like the canonical diverging electrostatic potential structure. Furthermore, the parallel potentials vary grossly in spatial/temporal scale, peak voltage and associated parallel current density. Here, we present a comprehensive study of these structures in Jupiter's downward current region focusing on energetic particle measurements from Juno-JEDI.

  9. Experimental study on liquid velocity in upward and downward two-phase flows

    International Nuclear Information System (INIS)

    Sun, X.; Paranjape, S.; Kim, S.; Ozar, B.; Ishii, M.

    2003-01-01

    Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral Laser Doppler Anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void weighted area-averaged drift velocity were obtained based on the definitions

  10. Interfacial structures and area transport in upward and downward two-phase flow

    International Nuclear Information System (INIS)

    Paranjape, S. S.; Kim, S.; Ishii, M.; Kelly, J.

    2003-01-01

    An experimental study has been carried out for upward and downward two-phase flow to study local interfacial structures and interfacial area transport. The flow studied, is an adiabatic, air-water, co-current, two-phase flow, in 25.4 mm and 50.8 mm ID test sections. Flow regime map is obtained using the characteristic signals obtained from an impedance void meter, employing neural network based identification methodology. A four sensor conductivity probe is used to measure the local two phase flow parameters, in bubbly flow regime. The local profiles of these parameters as well as their axial development reveal the nature of the interfacial structures and the bubble interaction mechanisms occurring in the flow. Furthermore, this study provides a good database for the development of the interfacial area transport equation, which dynamically models the changes in the interfacial area along a flow field. An interfacial area transport equation is used for downward flow based on that developed for the upward flow, with certain modifications in the bubble interaction terms. The area averaged values of the interfacial area concentration are compared with those predicted by the interfacial area transport model. The differences in the interfacial structures and interfacial area transport in co-current downward and upward two-phase flows are studied

  11. The onset of flow instability for a downward flow of a non-boiling heated liquid

    International Nuclear Information System (INIS)

    Babelli, Ibrahim; Ishii, Mamoru

    1999-01-01

    A procedure for predicting the onset of flow instability (OFI) in downward flows at low-pressure and low-flow conditions without boiling is presented in this paper. It is generally accepted that the onset of significant void in subcooled boiling precedes, and is a precondition to, the occurrence of static flow instability. A detailed analysis of the pressure drop components for a downward flow in a heated channel reveals the possibility of unstable transition from single-phase flow to high-quality two-phase flow, i.e., flow excursion. Low flow rate and high subcooling are the two important conditions for the occurrence of this type of instability. The unstable transition occurs when the resistance to the downward flow caused by local (orifice), frictional, and thermal expansion pressure drops equalizes the driving force of the gravitational pressure drop. The inclusion of the thermal expansion pressure drop is essential to account for this type of transition. Experimental data are yet to be produced to verify the prediction of the present analysis. (author)

  12. Premature and stable critical heat flux for downward flow in a narrow rectangular channel

    International Nuclear Information System (INIS)

    Lee, Juhyung; Chang, Soon Heung; Jeong, Yong Hoon; Jo, Daeseong

    2014-01-01

    It has been recommended that RRs and MTRs be designed to have sufficient margins for CHF and the onset of FI as well, since unstable flow could leads to premature CHF under very low wall heat flux in comparison to stable CHF. Even the fact and previous studies, however, the understanding of relationship among FI, premature CHF and stable CHF is not sufficient to date. In this regards, subcooled flow boiling in a vertical rectangular channel was experimentally investigated to enhance the understanding of the CHF and the effect of the two-phase flow instability on it under low pressure conditions, especially for downward flow which was adopted for Jordan Research and Training Reactor (JRTR) and Kijang research reactor (KJRR) to achieve easier fuel and irradiation rig loading. In this study, CHF for downward flow of water under low pressure in narrow rectangular channel was experimentally investigated. For conditions such as downward flow, narrow rectangular channel and low pressure, it has been deduced from literature that flow instability could largely influence on triggering CHF at lower heat flux, i. e. premature CHF. Total 54 CHF data, which includes premature and stable data was obtained for various fluid conditions and system configurations including inlet stiffness. The upper and lower boundaries of CHF were newly proposed based on the experiment

  13. Long-wave equivalent viscoelastic solids for porous rocks saturated by two-phase fluids

    Science.gov (United States)

    Santos, J. E.; Savioli, G. B.

    2018-04-01

    Seismic waves traveling across fluid-saturated poroelastic materials with mesoscopic-scale heterogeneities induce fluid flow and Biot's slow waves generating energy loss and velocity dispersion. Using Biot's equations of motion to model these type of heterogeneities would require extremely fine meshes. We propose a numerical upscaling procedure to determine the complex and frequency dependent P-wave and shear moduli of an effective viscoelastic medium long-wave equivalent to a poroelastic solid saturated by a two-phase fluid. The two-phase fluid is defined in terms of capillary pressure and relative permeability flow functions. The P-wave and shear effective moduli are determined using harmonic compressibility and shear experiments applied on representative samples of the bulk material. Each experiment is associated with a boundary value problem that is solved using the finite element method. Since a poroelastic solid saturated by a two-phase fluid supports the existence of two slow waves, this upscaling procedure allows to analyze their effect on the mesoscopic-loss mechanism in hydrocarbon reservoir formations. Numerical results show that a two-phase Biot medium model predicts higher attenuation than classic Biot models.

  14. Long-wave, infrared laser-induced breakdown (LIBS) spectroscopy emissions from energetic materials.

    Science.gov (United States)

    Yang, Clayton S-C; Brown, Ei E; Hommerich, Uwe; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

    2012-12-01

    Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof. The silicon-based detector for conventional ultraviolet-visible LIBS operations was replaced with a mercury-cadmium-telluride detector for MIR-LWIR spectral detection. The IR spectral signature region between 4 and 12 μm was mined for the appearance of MIR and LWIR-LIBS emissions directly indicative of oxygenated breakdown products as well as dissociated, and/or recombined sample molecular fragments. Distinct LWIR-LIBS emission signatures from dissociated-recombination sample molecular fragments between 4 and 12 μm are observed for the first time.

  15. Integration of Absorption Feature Information from Visible to Longwave Infrared Spectral Ranges for Mineral Mapping

    Directory of Open Access Journals (Sweden)

    Veronika Kopačková

    2017-09-01

    Full Text Available Merging hyperspectral data from optical and thermal ranges allows a wider variety of minerals to be mapped and thus allows lithology to be mapped in a more complex way. In contrast, in most of the studies that have taken advantage of the data from the visible (VIS, near-infrared (NIR, shortwave infrared (SWIR and longwave infrared (LWIR spectral ranges, these different spectral ranges were analysed and interpreted separately. This limits the complexity of the final interpretation. In this study a presentation is made of how multiple absorption features, which are directly linked to the mineral composition and are present throughout the VIS, NIR, SWIR and LWIR ranges, can be automatically derived and, moreover, how these new datasets can be successfully used for mineral/lithology mapping. The biggest advantage of this approach is that it overcomes the issue of prior definition of endmembers, which is a requested routine employed in all widely used spectral mapping techniques. In this study, two different airborne image datasets were analysed, HyMap (VIS/NIR/SWIR image data and Airborne Hyperspectral Scanner (AHS, LWIR image data. Both datasets were acquired over the Sokolov lignite open-cast mines in the Czech Republic. It is further demonstrated that even in this case, when the absorption feature information derived from multispectral LWIR data is integrated with the absorption feature information derived from hyperspectral VIS/NIR/SWIR data, an important improvement in terms of more complex mineral mapping is achieved.

  16. First Satellite-detected Perturbations of Outgoing Longwave Radiation Associated with Blowing Snow Events over Antarctica

    Science.gov (United States)

    Yang, Yuekui; Palm, Stephen P.; Marshak, Alexander; Wu, Dong L.; Yu, Hongbin; Fu, Qiang

    2014-01-01

    We present the first satellite-detected perturbations of the outgoing longwave radiation (OLR) associated with blowing snow events over the Antarctic ice sheet using data from Cloud-Aerosol Lidar with Orthogonal Polarization and Clouds and the Earth's Radiant Energy System. Significant cloud-free OLR differences are observed between the clear and blowing snow sky, with the sign andmagnitude depending on season and time of the day. During nighttime, OLRs are usually larger when blowing snow is present; the average difference in OLRs between without and with blowing snow over the East Antarctic Ice Sheet is about 5.2 W/m2 for the winter months of 2009. During daytime, in contrast, the OLR perturbation is usually smaller or even has the opposite sign. The observed seasonal variations and day-night differences in the OLR perturbation are consistent with theoretical calculations of the influence of blowing snow on OLR. Detailed atmospheric profiles are needed to quantify the radiative effect of blowing snow from the satellite observations.

  17. Recent developments in the line-by-line modeling of outgoing longwave radiation

    International Nuclear Information System (INIS)

    Buehler, S.A.; Engeln, A. von; Brocard, E.; John, V.O.; Kuhn, T.; Eriksson, P.

    2006-01-01

    High frequency resolution radiative transfer model calculations with the Atmospheric Radiative Transfer Simulator (ARTS) were used to simulate the clear-sky outgoing longwave radiative flux (OLR) at the top of the atmosphere. Compared to earlier calculations by Clough and coworkers the model used a spherical atmosphere instead of a plane parallel atmosphere, updated spectroscopic parameters from HITRAN, and updated continuum parameterizations from Mlawer and coworkers. These modifications lead to a reduction in simulated OLR by approximately 4.1%, the largest part, approximately 2.5%, being due to the absence of the plane parallel approximation. As a simple application of the new model, the sensitivity of OLR to changes in humidity, carbon dioxide concentration, and temperature were investigated for different cloud-free atmospheric scenarios. It was found that for the tropical scenario a 20% change in humidity has a larger impact than a doubling of the carbon dioxide concentration. The sensitive altitude region for temperature and humidity changes is the entire free troposphere, including the upper troposphere where humidity data quality is poor

  18. Long-wave model for strongly anisotropic growth of a crystal step.

    Science.gov (United States)

    Khenner, Mikhail

    2013-08-01

    A continuum model for the dynamics of a single step with the strongly anisotropic line energy is formulated and analyzed. The step grows by attachment of adatoms from the lower terrace, onto which atoms adsorb from a vapor phase or from a molecular beam, and the desorption is nonnegligible (the "one-sided" model). Via a multiscale expansion, we derived a long-wave, strongly nonlinear, and strongly anisotropic evolution PDE for the step profile. Written in terms of the step slope, the PDE can be represented in a form similar to a convective Cahn-Hilliard equation. We performed the linear stability analysis and computed the nonlinear dynamics. Linear stability depends on whether the stiffness is minimum or maximum in the direction of the step growth. It also depends nontrivially on the combination of the anisotropy strength parameter and the atomic flux from the terrace to the step. Computations show formation and coarsening of a hill-and-valley structure superimposed onto a long-wavelength profile, which independently coarsens. Coarsening laws for the hill-and-valley structure are computed for two principal orientations of a maximum step stiffness, the increasing anisotropy strength, and the varying atomic flux.

  19. Modelling of long-wave chaotic radar system for anti-stealth applications

    Science.gov (United States)

    Al-Suhail, Ghaida A.; Tahir, Fadhil Rahma; Abd, Mariam Hussien; Pham, Viet-Thanh; Fortuna, Luigi

    2018-04-01

    Although the Very Low-Frequency (VLF) waveforms have limited practical applications in acoustics (sonar) and secure military communications with radars and submarines; to this end; this paper presents a new and simple analytical model of VLF monostatic direct chaotic radar system. The model hypothetically depends on the two identical coupled time-delayed feedback chaotic systems which can generate and recover a long-wave chaotic signal. To resist the influence of positive Lyapunov exponents of the time-delay chaotic systems, the complete replacement of Pecaro and Carroll (PC) synchronization is employed. It can faithfully recover the chaotic signal from the back-scattered (echo) signal from the target over a noisy channel. The system performance is characterized in terms of the time series of synchronization in addition to the peak of the cross-correlation. Simulation results are conducted for substantial sensitivities of the chaotic signal to the system parameters and initial conditions. As a result, it is found that an effective and robust chaotic radar (CRADAR) model can be obtained when the signal-to-noise ratio (SNR) highly degrades to 0 dB, but with clear peak in correlation performance for detecting the target. Then, the model can be considered as a state of the art towards counter stealth technology and might be developed for other acoustic secure applications.

  20. Long-wave theory for a new convective instability with exponential growth normal to the wall.

    Science.gov (United States)

    Healey, J J

    2005-05-15

    A linear stability theory is presented for the boundary-layer flow produced by an infinite disc rotating at constant angular velocity in otherwise undisturbed fluid. The theory is developed in the limit of long waves and when the effects of viscosity on the waves can be neglected. This is the parameter regime recently identified by the author in a numerical stability investigation where a curious new type of instability was found in which disturbances propagate and grow exponentially in the direction normal to the disc, (i.e. the growth takes place in a region of zero mean shear). The theory describes the mechanisms controlling the instability, the role and location of critical points, and presents a saddle-point analysis describing the large-time evolution of a wave packet in frames of reference moving normal to the disc. The theory also shows that the previously obtained numerical solutions for numerically large wavelengths do indeed lie in the asymptotic long-wave regime, and so the behaviour and mechanisms described here may apply to a number of cross-flow instability problems.

  1. Mutagenicity of 8-methoxypsoralen and long-wave ultraviolet irradiation in V-79 Chinese hamster cells

    International Nuclear Information System (INIS)

    Burger, P.M.; Simons, J.W.I.M.

    1979-01-01

    The effect of 8-methoxypsoralen (8-MOP) and long-wave ultraviolet irradiation (UVA) on cell killing and mutation induction was studied in V-79 Chinese hamster cells. No effect was observed after treatment with 8-MOP alone (50 μg/ml, 4 h), UVA alone (9000 J/m 2 ), or 8-MOP metobolized by rat-liver microsomes. Combined treatment with 8-MOP and UVA induced both cell killing and mutation. This was also observed under conditins approaching patient treatment with PUVA photochemotherapy with respect to the concentration of 8-MOP in the skin and the amount of UVA received by the epidermal cells. A simple relation proved to apply for mutation induction under different treatment conditions: 5.5 X 10 -8 per J/m 2 per μg 8-MOP/ml. On this basis the mutation induction in dividing cells per session of PUVA-photochemotherapy amounts to 12.4 X 10 -5 , which is probably an over-estimation. (Auth.)

  2. Role of Longwave Cloud-Radiation Feedback in the Simulation of the Madden-Julian Oscillation

    Science.gov (United States)

    Kim, Daehyun; Ahn, Min-Seop; Kang, In-Sik; Del Genio, Anthony D.

    2015-01-01

    The role of the cloud-radiation interaction in the simulation of the Madden-Julian oscillation (MJO) is investigated. A special focus is on the enhancement of column-integrated diabatic heating due to the greenhouse effects of clouds and moisture in the region of anomalous convection. The degree of this enhancement, the greenhouse enhancement factor (GEF), is measured at different precipitation anomaly regimes as the negative ratio of anomalous outgoing longwave radiation to anomalous precipitation. Observations show that the GEF varies significantly with precipitation anomaly and with the MJO cycle. The greenhouse enhancement is greater in weak precipitation anomaly regimes and its effectiveness decreases monotonically with increasing precipitation anomaly. The GEF also amplifies locally when convection is strengthened in association with the MJO, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). A robust statistical relationship is found among CMIP5 climate model simulations between the GEF and the MJO simulation fidelity. Models that simulate a stronger MJO also simulate a greater GEF, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). Models with a greater GEF in the strong precipitation anomaly regime (greater than 30 mm day(-1)) represent a slightly slower MJO propagation speed. Many models that lack the MJO underestimate the GEF in general and in particular in the weak precipitation anomaly regime. The results herein highlight that the cloud-radiation interaction is a crucial process for climate models to correctly represent the MJO.

  3. Downward migration of radiocesium in an abandoned paddy soil after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Takahashi, Junko; Wakabayashi, Shokichi; Tamura, Kenji; Onda, Yuichi

    2018-02-01

    After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, continuous monitoring of the detailed vertical distribution of radiocesium in soil is required to evaluate the fate of radiocesium and establish strategies for remediation and management of the contaminated land. It is especially important to investigate paddy soil because little knowledge has been accumulated for paddy soil and wetland rice is a major staple in Japan. Therefore, we monitored the vertical distribution of 137 Cs in abandoned paddy soil in a planned evacuation zone from June 2011 to March 2016. The decontamination works (i.e., 5 cm of surface soil removal and re-covering with uncontaminated soil) were conducted by the government in 2015. As a result of monitoring, the 137 Cs gradually migrated downward with time and the 137 Cs concentration in the 0-10 cm soil was almost homogenous in October 2014, although it was non-cultivated. The liner relationship was obtained between the median depth, which is the thickness of a soil layer containing half of the total 137 Cs inventory, and the time after the accident, indicating the migration rate was constant (1.3 cm y -1 ) before the decontamination works. After the decontamination works, the 137 Cs concentration in the uppermost surface layer was reduced by 90%, however the total 137 Cs inventory was reduced by only 50-70%. It was shown that the efficiency of 137 Cs removal by the decontamination works decrease linearly over time in fields like the studied paddy, in which the homogenization of 137 Cs concentration occurred. Conversely, the downward migration of 137 Cs to subsurface layers deeper than 10 cm (i.e., plowpan layer) with low permeability rarely occurred. It is expected that these unique trends in distribution and migration of 137 Cs would be found in abandoned paddy soils with properties similar to the studied soil, sandy loam but poorly drained because of the low permeable plowpan layer, although further validation is

  4. Impact of Precipitating Ice Hydrometeors on Longwave Radiative Effect Estimated by a Global Cloud-System Resolving Model

    Science.gov (United States)

    Chen, Ying-Wen; Seiki, Tatsuya; Kodama, Chihiro; Satoh, Masaki; Noda, Akira T.

    2018-02-01

    Satellite observation and general circulation model (GCM) studies suggest that precipitating ice makes nonnegligible contributions to the radiation balance of the Earth. However, in most GCMs, precipitating ice is diagnosed and its radiative effects are not taken into account. Here we examine the longwave radiative impact of precipitating ice using a global nonhydrostatic atmospheric model with a double-moment cloud microphysics scheme. An off-line radiation model is employed to determine cloud radiative effects according to the amount and altitude of each type of ice hydrometeor. Results show that the snow radiative effect reaches 2 W m-2 in the tropics, which is about half the value estimated by previous studies. This effect is strongly dependent on the vertical separation of ice categories and is partially generated by differences in terminal velocities, which are not represented in GCMs with diagnostic precipitating ice. Results from sensitivity experiments that artificially change the categories and altitudes of precipitating ice show that the simulated longwave heating profile and longwave radiation field are sensitive to the treatment of precipitating ice in models. This study emphasizes the importance of incorporating appropriate treatments for the radiative effects of precipitating ice in cloud and radiation schemes in GCMs in order to capture the cloud radiative effects of upper level clouds.

  5. RELAP5 analysis of subcooled boiling appearance and disappearance in downward flow

    International Nuclear Information System (INIS)

    Ristevski, R.; Parzer, I.; Spasojevic, D.

    1999-01-01

    The presented paper will mainly consider heat and mass transfer phenomenology in the subcooled boiling regime of downward liquid flow at low velocities. More specifically, it will focus on the effects of appearance and disappearance of two-phase flow at low liquid velocities, in the area where gravity force has significant influence. Two among a series of tests performed on a high-pressure circulation loop, installed in Vinca, will be analyzed. The experimental findings and theoretical consideration of these processes and phenomena will be compared with RELAP5/MOD3.2.2 predictions.(author)

  6. Flow Boiling on a Downward-Facing Inclined Plane Wall of Core Catcher

    International Nuclear Information System (INIS)

    Kim, Hyoung Tak; Bang, Kwang Hyun; Suh, Jung Soo

    2013-01-01

    In order to investigate boiling behavior on downward-facing inclined heated wall prior to the CHF condition, an experiment was carried out with 1.2 m long rectangular channel, inclined by 10 .deg. from the horizontal plane. High speed video images showed that the bubbles were sliding along the heated wall, continuing to grow and combining with the bubbles growing at their nucleation sites in the downstream. These large bubbles continued to slide along the heated wall and formed elongated slug bubbles. Under this slug bubble thin liquid film layer on the heated wall was observed and this liquid film prevents the wall from dryout. The length, velocity and frequency of slug bubbles sliding on the heated wall were measured as a function of wall heat flux and these parameters were used to develop wall boiling model for inclined, downward-facing heated wall. One approach to achieve coolable state of molten core in a PWR-like reactor cavity during a severe accident is to retain the core melt on a so-called core catcher residing on the reactor cavity floor after its relocation from the reactor pressure vessel. The core melt retained in the core catcher is cooled by water coolant flowing in an inclined cooling channel underneath as well as the water pool overlaid on the melt layer. Two-phase flow boiling with downward-facing heated wall such as this core catcher cooling channel has drawn a special attention because this orientation of heated wall may reach boiling crisis at lower heat flux than that of a vertical or upward-facing heated wall. Nishikawa and Fujita, Howard and Mudawar, Qiu and Dhir have conducted experiments to study the effect of heater orientation on boiling heat transfer and CHF. SULTAN experiment was conducted to study inclined large-scale structure coolability by water in boiling natural convection. In this paper, high-speed visualization of boiling behavior on downward-facing heated wall inclined by 10 .deg. is presented and wall boiling model for the

  7. Downward Price-Based Brand Line Extensions Effects on Luxury Brands

    OpenAIRE

    Royo-Vela, Marcelo; Voss, Eileen

    2015-01-01

    This study tries to examine the brand concept consistency, the self-concept congruence and the resulting loyalty status of the consumers in order to evaluate whether a downward price-based line extensions in the luxury goods market has any negative or positive effect on them. By conducting focus group and in-depth interviews it was tried to filter out how brand concepts of luxury brands are perceived before and after a line extension. Results revealed that a crucial aspect for the evaluation ...

  8. Study of natural energy system and downward atmospheric radiation. Part 1. Outline on measurement and result on downward atmospheric radiation; Shizen energy system to tenku hosharyo no kansoku kenkyu. 1. Kisho kansoku gaiyo to tenku hosharyo no kansoku kekka

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, K [Kogakuin University, Tokyo (Japan); Masuoka, Y [Yokogawa Architects and Engineers, Inc., Tokyo (Japan)

    1996-10-27

    For the study of a natural energy system taking advantage of radiation cooling, a simplified method for estimating downward atmospheric radiation quantities was examined, using observation records supplied from Hachioji City, Aerological Observatory in Tsukuba City, and four other locations. Downward atmospheric radiation quantities are closely related to partial vapor pressure in the atmosphere. Because partial vapor pressure changes according to the season, it was classified into two, for summer and for winter, and was referred to downward atmospheric radiation quantities for the establishment of their correlationships. Downward atmospheric radiation quantities were predicted on the basis of meteorological factors such as partial vapor pressure and free air temperature. Accuracy was examined of the simplified estimation equation for downward atmospheric radiation that had been proposed. A multiple regression analysis was carried out for calculating constants for the estimation equation, using partial vapor pressure, Stefan-Boltzmann constant, and free air dry-bulb absolute temperature, all closely correlated with atmospheric downward radiation quantities. Accuracy improved by time-based classification. At night, use of SAT (equivalent free air temperature) produced more accurate estimation. Though dependent upon local characteristics of the observation spot, the estimation equation works effectively. 10 refs., 10 figs., 3 tabs.

  9. Development of a Convective Heat Transfer Correlation of a Supercritical CO2 with Vertical Downward Flow in Circular Tubes

    International Nuclear Information System (INIS)

    Yoo, Tae Ho; Kim, Hwan Yeol; Bae, Yoon Yeong

    2009-01-01

    Pressure of coolant flowing through a SCWR core subchannel is supercritical and the heat transfer behavior is known to be quite different from those at a subcritical pressure. Therefore the heat transfer study in a supercritical pressure is required for the acquisition of a reliable heat transfer correlation. A downward flow as well as an upward flow occurs in a multi-pass reactor core. The heat transfer at a supercritical pressure in downward channel has been known to result in a quite different behavior from an upward flow. An experiment for a supercritical CO 2 flowing vertically downward in circular tubes with inner diameters of 6.32 mm and 9 mm was performed by using SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation) at KAERI. The obtained test results are compared with the estimations from the existing correlations and an empirical formula for a downward flow is suggested

  10. Removal of NAPLs from the unsaturated zone using steam: prevention of downward migration by injecting mixtures of steam and air

    DEFF Research Database (Denmark)

    Schmidt, R.; Gudbjerg, Jacob; Sonnenborg, Torben Obel

    2002-01-01

    injection technology is presented, where a mixture of steam and air was injected. In twodimensional experiments with unsaturated porous medium contaminated with nonaqueous phase liquids, it was demonstrated how injection of pure steam lead to severe downward migration. Similar experiments, where steam......Steam injection for remediation of porous media contaminated by nonaqueous phase liquids has been shown to be a potentially efficient technology. There is, however, concern that the technique may lead to downward migration of separate phase contaminant. In this work, a modification of the steam...... and air were injected simultaneously, resulted in practically no downward migration and still rapid cleanup was achieved. The processes responsible for the prevention of downward migration when injecting steam–air mixtures were analyzed using a nonisothermal multiphase flow and transport model. Hereby...

  11. A stable downward continuation of airborne magnetic data: A case study for mineral prospectivity mapping in Central Iran

    Science.gov (United States)

    Abedi, Maysam; Gholami, Ali; Norouzi, Gholam-Hossain

    2013-03-01

    Previous studies have shown that a well-known multi-criteria decision making (MCDM) technique called Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE II) to explore porphyry copper deposits can prioritize the ground-based exploratory evidential layers effectively. In this paper, the PROMETHEE II method is applied to airborne geophysical (potassium radiometry and magnetometry) data, geological layers (fault and host rock zones), and various extracted alteration layers from remote sensing images. The central Iranian volcanic-sedimentary belt is chosen for this study. A stable downward continuation method as an inverse problem in the Fourier domain using Tikhonov and edge-preserving regularizations is proposed to enhance magnetic data. Numerical analysis of synthetic models show that the reconstructed magnetic data at the ground surface exhibits significant enhancement compared to the airborne data. The reduced-to-pole (RTP) and the analytic signal filters are applied to the magnetic data to show better maps of the magnetic anomalies. Four remote sensing evidential layers including argillic, phyllic, propylitic and hydroxyl alterations are extracted from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images in order to map the altered areas associated with porphyry copper deposits. Principal component analysis (PCA) based on six Enhanced Thematic Mapper Plus (ETM+) images is implemented to map iron oxide layer. The final mineral prospectivity map based on desired geo-data set indicates adequately matching of high potential zones with previous working mines and copper deposits.

  12. Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number

    KAUST Repository

    Yoon, Sung Hwan

    2017-10-12

    According to previous theory, pulsating propagation in a premixed flame only appears when the reduced Lewis number, β(Le-1), is larger than a critical value (Sivashinsky criterion: 4(1 +3) ≈ 11), where β represents the Zel\\'dovich number (for general premixed flames, β ≈ 10), which requires Lewis number Le > 2.1. However, few experimental observation have been reported because the critical reduced Lewis number for the onset of pulsating instability is beyond what can be reached in experiments. Furthermore, the coupling with the unavoidable hydrodynamic instability limits the observation of pure pulsating instabilities in flames. Here, we describe a novel method to observe the pulsating instability. We utilize a thermoacoustic field caused by interaction between heat release and acoustic pressure fluctuations of the downward-propagating premixed flames in a tube to enhance conductive heat loss at the tube wall and radiative heat loss at the open end of the tube due to extended flame residence time by diminished flame surface area, i.e., flat flame. The thermoacoustic field allowed pure observation of the pulsating motion since the primary acoustic force suppressed the intrinsic hydrodynamic instability resulting from thermal expansion. By employing this method, we have provided new experimental observations of the pulsating instability for premixed flames. The Lewis number (i.e., Le ≈ 1.86) was less than the critical value suggested previously.

  13. Extracting Leaf Area Index by Sunlit Foliage Component from Downward-Looking Digital Photography under Clear-Sky Conditions

    Directory of Open Access Journals (Sweden)

    Yelu Zeng

    2015-10-01

    Full Text Available The development of near-surface remote sensing requires the accurate extraction of leaf area index (LAI from networked digital cameras under all illumination conditions. The widely used directional gap fraction model is more suitable for overcast conditions due to the difficulty to discriminate the shaded foliage from the shadowed parts of images acquired on sunny days. In this study, a new LAI extraction method by the sunlit foliage component from downward-looking digital photography under clear-sky conditions is proposed. In this method, the sunlit foliage component was extracted by an automated image classification algorithm named LAB2, the clumping index was estimated by a path length distribution-based method, the LAD and G function were quantified by leveled digital images and, eventually, the LAI was obtained by introducing a geometric-optical (GO model which can quantify the sunlit foliage proportion. The proposed method was evaluated at the YJP site, Canada, by the 3D realistic structural scene constructed based on the field measurements. Results suggest that the LAB2 algorithm makes it possible for the automated image processing and the accurate sunlit foliage extraction with the minimum overall accuracy of 91.4%. The widely-used finite-length method tends to underestimate the clumping index, while the path length distribution-based method can reduce the relative error (RE from 7.8% to 6.6%. Using the directional gap fraction model under sunny conditions can lead to an underestimation of LAI by (1.61; 55.9%, which was significantly outside the accuracy requirement (0.5; 20% by the Global Climate Observation System (GCOS. The proposed LAI extraction method has an RMSE of 0.35 and an RE of 11.4% under sunny conditions, which can meet the accuracy requirement of the GCOS. This method relaxes the required diffuse illumination conditions for the digital photography, and can be applied to extract LAI from downward-looking webcam images

  14. Inhibition of human peripheral blood lymphocyte function by protoporphyrin and longwave ultraviolet light

    International Nuclear Information System (INIS)

    Barrett, K.E.; Yen, A.; Montisano, D.; Gigli, I.; Bigby, T.D.

    1994-01-01

    Modulation of immunologic effector cells by exogenous photoactive substances has been advanced as an underlying mechanism for the efficacy of various photochemotherapeutic regimens. It is also possible that endogenous photosensitizers, such as protoporphyrin, could similarly modify the function of immune cell types. The authors examined the effects of protoporphyrin plus longwave UV light on the ability of human PBL to proliferate in response to mitogens. Noncytotoxic dosages of protoporphyrin plus UV light suppressed PHA-stimulated proliferation of both PBMC and enriched T cells. CD8 + cells were more sensitive to this inhibitory effect than CD4 + cells. The inhibitory effect was also observed when proliferation was induced by the combination of a phorbol ester and ionomycin. Inhibition of PBMC proliferation was associated with inhibition of IL-2 secretion but proliferation was not restored with exogenous IL-2. Instead, the effect of protoporphyrin plus UV light may be on IL-2R. Cells treated with protoporphyrin and UV light did not display the increase in CD25 and β-chain of the IL-2R induced by PHA in control cells. In contrast to the effects of protoporphyrin and UV light on IL-2 and IL-2R α-chain protein expression, the accumulation of mRNA for these proteins induced by PHA was unaffected. None of the effects of protoporphyrin plus UV light on lymphocytes were observed in control experiments where cells were treated with either protoporphyrin or UV light alone. They conclude that biologically relevant dosages of protoporphyrin and UV light modify the function of circulating lymphocytes. 26 refs., 8 figs., 1 tab

  15. The downward spiral of chronic pain, prescription opioid misuse, and addiction: cognitive, affective, and neuropsychopharmacologic pathways.

    Science.gov (United States)

    Garland, Eric L; Froeliger, Brett; Zeidan, Fadel; Partin, Kaitlyn; Howard, Matthew O

    2013-12-01

    Prescription opioid misuse and addiction among chronic pain patients are emerging public health concerns of considerable significance. Estimates suggest that more than 10% of chronic pain patients misuse opioid analgesics, and the number of fatalities related to nonmedical or inappropriate use of prescription opioids is climbing. Because the prevalence and adverse consequences of this threat are increasing, there is a pressing need for research that identifies the biobehavioral risk chain linking chronic pain, opioid analgesia, and addictive behaviors. To that end, the current manuscript draws upon current neuropsychopharmacologic research to provide a conceptual framework of the downward spiral leading to prescription opioid misuse and addiction among chronic pain patients receiving opioid analgesic pharmacotherapy. Addictive use of opioids is described as the outcome of a cycle initiated by chronic pain and negative affect and reinforced by opioidergic-dopamingeric interactions, leading to attentional hypervigilance for pain and drug cues, dysfunctional connectivity between self-referential and cognitive control networks in the brain, and allostatic dysregulation of stress and reward circuitry. Implications for clinical practice are discussed; multimodal, mindfulness-oriented treatment is introduced as a potentially effective approach to disrupting the downward spiral and facilitating recovery from chronic pain and opioid addiction. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Void fraction in steam-water mixture downward motion in tubes and intertubular spaces

    International Nuclear Information System (INIS)

    Miropol'skij, Z.L.; Shneerova, R.I.; Karamysheva, A.I.

    1978-01-01

    Experiments have been carried out with a view to determining the averaged cross-section virtual steam contents for downward steam-air mixture flows in a pipe (diameter 40 mm, length 600 mm) and in a 400 mm-long cylindrical channel, which accomodated 19 cylindrical tubes. Equivalent channel diameter was 9.2 mm. The tests were carried out both under adiabatic flow conditions and in the presence of heat transfer through pipes, which were electrically heated. The p pressure was 3 mPa, specific heat fluxes g=0-0.27 MW/m 2 , mass rates wsub(p)=110-395 kg/m 2 xs in the tube bunch and 95-345 kg/m 2 xs in the pipe. The test results indicate that: the virtual volumetric steam contents in a downward flow of a steam-air mixture are higher than those in an upward flow; x in a tube bunch is substantially smaller than that in a pipe

  17. Satellite Based Downward Long Wave Radiation by Various Models in Northeast Asia

    Directory of Open Access Journals (Sweden)

    Chanyang Sur

    2014-01-01

    Full Text Available Satellite-based downward long wave radiation measurement under clear sky conditions in Northeast Asia was conducted using five well-known physical models (Brunt 1932, Idso and Jackson 1969, Brutsaert 1975, Satterlund 1979, Prata 1996 with a newly proposed global Rld model (Abramowitz et al. 2012. Data from two flux towers in South Korea were used to validate downward long wave radiation. Moderate resolution imaging spectroradiometer (MODIS atmospheric profile products were used to develop the Rld models. The overall root mean square error (RMSE of MODIS Rld with respect to two ecosystem-type flux towers was determined to be ≈ 20 W m-2. Based on the statistical analyses, MODIS Rld estimates with Brutsaert (1975 and Abramowitz et al. (2012 models were the most applicable for evaluating Rld for clear sky conditions in Northeast Asia. The Abramowitz Rld maps with MODIS Ta and ea showed reasonable seasonal patterns, which were well-aligned with other biophysical variables reported by previous studies. The MODIS Rld map developed in this study will be very useful for identifying spatial patterns that are not detectable from ground-based Rld measurement sites.

  18. A unified engineering model of the first stroke in downward negative lightning

    Science.gov (United States)

    Nag, Amitabh; Rakov, Vladimir A.

    2016-03-01

    Each stroke in a negative cloud-to-ground lightning flash is composed of downward leader and upward return stroke processes, which are usually modeled individually. The first stroke leader is stepped and starts with preliminary breakdown (PB) which is often viewed as a separate process. We present the first unified engineering model for computing the electric field produced by a sequence of PB, stepped leader, and return stroke processes, serving to transport negative charge to ground. We assume that a negatively charged channel extends downward in a stepped fashion during both the PB and leader stages. Each step involves a current wave that propagates upward along the newly formed channel section. Once the leader attaches to ground, an upward propagating return stroke neutralizes the charge deposited along the channel. Model-predicted electric fields are in reasonably good agreement with simultaneous measurements at both near (hundreds of meters, electrostatic field component is dominant) and far (tens of kilometers, radiation field component is dominant) distances from the lightning channel. Relations between the features of computed electric field waveforms and model input parameters are examined. It appears that peak currents associated with PB pulses are similar to return stroke peak currents, and the observed variation of electric radiation field peaks produced by leader steps at different heights above ground is influenced by the ground corona space charge.

  19. Effects of fuel properties on the natural downward smoldering of piled biomass powder: Experimental investigation

    International Nuclear Information System (INIS)

    He, Fang; Yi, Weiming; Li, Yongjun; Zha, Jianwen; Luo, Bin

    2014-01-01

    To validate the modeling of one-dimensional biomass smoldering and combustion, the effects of fuel type, moisture content and particle size on the natural downward smoldering of biomass powder have been investigated experimentally. A cylindrical reactor (inner size Φ26 cm × 22 cm) was constructed, and corn stalk, pine trunk, pyrolysis char and activated char from corn stalk were prepared as powders. The smoldering characteristics were examined for each of the four materials and for different moisture contents and particle sizes. The results revealed the following: 1) The maximum temperature in the fuel bed is only slightly affected by the fuel type and particle size. It increases gradually for original biomass and decreases slowly for chars with the development of the process. 2) The propagation velocity of the char oxidation front is significantly affected by the carbon density and ash content and nearly unaffected by moisture content and particle size. 3) The propagation velocity of the drying front is significantly affected by the moisture content, decreasing from over 10 times the propagation velocity of char oxidation front to about 3 times as the moisture content increased from 3 to 21%. - Highlights: • Natural downward smoldering of four materials, different moisture contents, and different particle sizes were investigated. • Propagation velocity of the char oxidation front differs significantly from that of the drying front. • Carbon density and ash content of fuel significantly affect propagation velocity of the char oxidation front

  20. Impacts of Saharan dust on downward irradiance and photosynthetically available radiation in the water column

    Directory of Open Access Journals (Sweden)

    T. Ohde

    2012-09-01

    Full Text Available A semi-empirical approach was used to quantify the modification of the underwater light field in amplitude (magnitude effect and spectral distribution (spectral effect by different atmospheric conditions altering the incident light. The approach based on an optical model in connection with radiation measurements in the area off Northwest Africa. Key inputs of the model were parameterized magnitude and spectral effects. Various atmospheric conditions were considered: clear sky, dusty sky without clouds, cloudy sky without dust and skies with different ratios of dust and clouds. Their impacts were investigated concerning the modification of the downward irradiance and photosynthetically available radiation in the water column. The impact on downward irradiance depended on the wavelength, the water depth, the optical water properties, the dust and cloud properties, and the ratio of clouds to dust. The influence of clouds on the amplitude can be much higher than that of dust. Saharan dust reduced the photosynthetically available radiation in the water column. Ocean regions were more influenced than coastal areas. Compensations of the magnitude and spectral effects were observed at special water depths in ocean regions and at atmospheric conditions with definite cloud to dust ratios.

  1. Heating limits of boiling downward two-phase flow in parallel channels

    International Nuclear Information System (INIS)

    Fukuda, Kenji; Kondoh, Tetsuya; Hasegawa, Shu; Sakai, Takaaki.

    1989-01-01

    Flow characteristics and heating limits of downward two-phase flow in single or parallel multi-channels are investigated experimentally and analytically. The heating section used is made of glass tube, in which the heater tube is inserted, and the flow regime inside it is observed. In single channel experiments with low flow rate conditions, it is found that, initially, gas phase which flows upward against the downward liquid phase flow condenses and diminishes as it flows up being cooled by inflowing liquid. However, as the heating power is increased, some portion of the gas phase reaches the top and accumulates to form an liquid level, which eventually causes the dryout. On the other hand, for high flow rate condition, the flooding at the bottom of the heated section is the cause of the dryout. In parallel multi-channels experiments, reversed (upward) flow which leads to the dryout is observed in some of these channels for low flow rate conditions, while the situation is the same to the single channel case for high flow rate conditions. Analyses are carried out to predict the onset of dryout in single channel using the drift flux model as well as the Wallis' flooding correlation. Above-mentioned two types of the dryout and their boundary are predicted which agree well with the experimental results. (author)

  2. Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

    Science.gov (United States)

    Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

    2015-11-20

    In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

  3. Characteristics of downward leaders in a cloud-to-ground lightning strike on a lightning rod

    Science.gov (United States)

    Wang, Caixia; Sun, Zhuling; Jiang, Rubin; Tian, Yangmeng; Qie, Xiushu

    2018-05-01

    A natural downward negative cloud-to-ground (CG) lightning was observed at a close distance of 370 m by using electric field change measurements and a high-speed camera at 5400 frames per second (fps). Two subsequent leader-return strokes of the lightning hit a lightning rod installed on the top of a seven-story building in Beijing city, while the grounding point for the stepped leader-first return stroke was 12 m away, on the roof of the building. The 2-D average speed of the downward stepped leader (L1) before the first return stroke (R1) was approximately 5.1 × 104 m/s during its propagation over the 306 m above the building, and those before the subsequent strokes (R2 and R3) ranged from 1.1 × 106 m/s to 2.2 × 106 m/s. An attempted leader (AL) occurred 201 ms after R1 and 10 ms before R2 reached approximately 99 m above the roof and failed to connect to the ground. The 2-D average speed of the AL was approximately 7.4 × 104 m/s. The luminosity at tip of the leader was brighter than the channel behind it. The leader inducing the R2 with an alteration of terminating point was a dart-stepped leader (DSL), which propagated through the channel of AL and continued to develop downward with new branches at about 17 m above the roof. The 2-D speed of the DSL at the bottom 99 m was 6.6 × 105 m/s. The average time interval between the stepped pulses of the DSL was approximately 10 μs, smaller than that of L1 with value of about 17 μs. The average step lengths of the DSL were approximately 6.6 m. The study shows that the stepped leader-first return stroke of lightning will not always hit the tip of a tall metal rod due to the significant branching property of the leader. However, under certain conditions, the subsequent return strokes may alter the grounding point to the tip of a tall metal rod. For the lightning rod, the protection against subsequent return strokes may be better than that against the first return stroke.

  4. Far-zone contributions of airborne gravity anomalies' upward/downward continuation

    Directory of Open Access Journals (Sweden)

    Boyang Zhou

    2016-11-01

    Full Text Available Airborne gravimetry has become a vital technique in local gravity field approximation, and upward/downward continuation of gravity data is a key process of airborne gravimetry. In these procedures, the integral domain is divided into two parts, namely the near-zone and the far-zone. The far-zone contributions are approximated by the truncation coefficients and a global geo-potential model, and their values are controlled by several issues. This paper investigates the effects of flight height, the size of near-zone cap, and Remove-Compute-Restore (RCR technique upon far-zone contributions. Results show that at mountainous area the far-zone contributions can be ignored when EIGEN-6C of 360 degree is removed from the gravity data, together with a near-zone cap of 1° and a flight height less than 10 km, while at flat area EIGEN-6C of 180 degree is feasible.

  5. Collector Efficiency in Downward-Type Internal-Recycle Solar Air Heaters with Attached Fins

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2013-10-01

    Full Text Available The internal-recycle operation effect on collector efficiency in downward-type rectangular solar air heaters with attached fins is theoretically investigated. It is found that considerable collector efficiency is obtainable if the collector has attached fins and the operation is carried out with internal recycling. The recycling operation increases the fluid velocity to decrease the heat transfer resistance, compensating for the undesirable effect of decreasing the heat transfer driving force (temperature difference due to remixing. The attached fins provide an enlarged heat transfer area. The order of performance in a device of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

  6. Heavy mineral sorting in downwards injected Palaeocene sandstone, Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Svendsen, Johan Byskov

    2011-01-01

    Post-depositional remobilization and injection of sand are often seen in deep-water clastic systems and has been recently recognised as a significant modifier of deep-water sandstone geometry. Large-scale injectite complexes have been interpreted from borehole data in the Palaeocene Siri Canyon...... of depositional structures in deep-water sandstones, the distinction between "in situ" and injected or remobilised sandstones is often ambiguous. Large scale heavy mineral sorting (in 10 m thick units) is observed in several reservoir units in the Siri Canyon and has been interpreted to represent the depositional...... sorting. In this study we describe an example of effective shear-zone sorting of heavy minerals in a thin downward injected sandstone dyke which was encountered in one of the cores in the Cecilie Field, Siri Canyon. Differences in sorting pattern of heavy minerals are suggested as a tool for petrographic...

  7. Research on the Flow Field and Structure Optimization in Cyclone Separator with Downward Exhaust Gas

    Directory of Open Access Journals (Sweden)

    Wang Weiwei

    2017-01-01

    Full Text Available A numerical software analysis of the turbulent and strongly swirling flow field of a cyclone separator with downward exhaust gas and its performances is described. The ANSYS 14.0 simulations based on DPM model are also used in the investigation. A new set of geometrical design has been optimized to achieve minimum pressure drop and maximum separation efficiency. A comparison of numerical simulation of the new design confirm the superior performance of the new design compared to the conventional design. The influence of the structure parameters such as the length of the guide pipe, the shape of the guide, the inlet shape on the separation performance was analyzed in this research. This research result has certain reference value for cyclone separator design and performance optimization.

  8. Concepts of self-acting circulation loops for downward heat transfer (reverse thermosiphons)

    International Nuclear Information System (INIS)

    Dobriansky, Y.

    2011-01-01

    This paper reviews the scientific and technical knowledge related to general self-acting flow loops (thermosiphons and heat pipes) that transmit heat upwards and self-acting reverse flow loops that transmit heat downwards. This paper classifies the heat and mass transfer processes that take place in general flow loops and analyses the nomenclature applied in the literature. It also presents the principles of operation of sixteen reverse flow loops; four of the loops are powered by an external source of energy, while the remaining loops are self-acting. Of the self-acting loops, vapor was used for heat transfer in seven of them and liquid was used in the remaining ones. Based on the available research results, a list of the advantages and disadvantages of both types of loops is presented.

  9. Downward economic mobility and preterm birth: an exploratory study of Chicago-born upper class White mothers.

    Science.gov (United States)

    Collins, James W; Rankin, Kristin M; David, Richard J

    2015-07-01

    A paucity of published data exists on the factors underlying the relatively poor birth outcome of non-Hispanic White women in the United States. To determine whether downward economic mobility is a risk factor for preterm birth (births of Chicago-born upper-class (defined by early-life residence in affluent neighborhoods) non-Hispanic White women. Upper class-born White women (n = 4,891) who did not experience downward economic mobility by the time of delivery had a PTB rate of 5.4 %. Those women who experienced slight (n = 5,112), moderate (n = 2,158), or extreme (n = 339) downward economic mobility had PTB rates of 6.5, 8.5, and 10.1 %, respectively; RR (95 % CI) = 1.2 (1.0-4.0), 1.6 (1.3-1.9), and 1.9 (1.3-2.6), respectively. Maternal downward economic mobility was also associated with an increased prevalence of biologic, medical, and behavioral risk factors. Interestingly, the relationship between moderate to extreme downward mobility and preterm birth was stronger among former low birth weight (birth for former LBW and non-LBW women who experienced any downward mobility (compared to those women with lifelong upper class status) equaled 2.4 (1.1-5.3) and 1.1 (1.0-1.1), respectively. Downward economic mobility is associated with an increased risk of preterm birth among upper class-born White urban women; this phenomenon is strongest among former low birth weight women.

  10. Experimental study on interfacial area transport in downward two-phase flow

    Science.gov (United States)

    Wang, Guanyi

    In view of the importance of two group interfacial area transport equations and lack of corresponding accurate downward flow database that can reveal two group interfacial area transport, a systematic database for adiabatic, air-water, vertically downward two-phase flow in a round pipe with inner diameter of 25.4 mm was collected to gain an insight of interfacial structure and provide benchmarking data for two-group interfacial area transport models. A four-sensor conductivity probe was used to measure the local two phase flow parameters and data was collected with data sampling frequency much higher than conventional data sampling frequency to ensure the accuracy. Axial development of local flow parameter profiles including void fraction, interfacial area concentration, and Sauter mean diameter were presented. Drastic inter-group transfer of void fraction and interfacial area was observed at bubbly to slug transition flow. And the wall peaked interfacial area concentration profiles were observed in churn-turbulent flow. The importance of local data about these phenomenon on flow structure prediction and interfacial area transport equation benchmark was analyzed. Bedsides, in order to investigate the effect of inlet conditions, all experiments were repeated after installing the flow straightening facility, and the results were briefly analyzed. In order to check the accuracy of current data, the experiment results were cross-checked with rotameter measurement as well as drift-flux model prediction, the averaged error is less than 15%. Current models for two-group interfacial area transport equation were evaluated using these data. The results show that two-group interfacial area transport equations with current models can predict most flow conditions with error less than 20%, except some bubbly to slug transition flow conditions and some churn-turbulent flow conditions. The disagreement between models and experiments could result from underestimate of inter

  11. Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

    Science.gov (United States)

    Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel

    2018-06-01

    Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

  12. Kinematic differences exist between transtibial amputee fallers and non-fallers during downwards step transitioning.

    Science.gov (United States)

    Vanicek, Natalie; Strike, Siobhán C; Polman, Remco

    2015-08-01

    Stair negotiation is biomechanically more challenging than level gait. There are few biomechanical assessments of transtibial amputees descending stairs and none specifically related to falls. Stair descent may elicit more differences than level gait in amputees with and without a previous falls history. The aim of this study was to compare the gait kinematics of fallers and non-fallers during downwards step transitioning in transtibial amputees. Cross-sectional study. Six fallers and five non-fallers completed step transition trials on a three-step staircase at their self-selected pace. Nine participants exhibited a clear preference to lead with the affected limb, while two had no preference. Four participants self-selected a step-to rather than a reciprocal stair descent strategy. The fallers who used a reciprocal strategy walked 44% more quickly than the non-fallers. To compensate for the lack of active plantar flexion of the prosthetic foot, exaggerated range of motion occurred proximally at the pelvis during swing. The step-to group was more reliant on the handrails than the reciprocal group and walked more slowly. As anticipated, the fallers walked faster than the non-fallers despite employing the more difficult 'roll-over' technique. Handrail use could help to improve dynamic control during downwards step transitions. Transtibial amputees are advised to descend steps using external support, such as handrails, for enhanced dynamic control. Hip abductor and knee extensor eccentric strength should be improved through targeted exercise. Prosthetic socket fit should be checked to allow adequate knee range of motion on the affected side. © The International Society for Prosthetics and Orthotics 2014.

  13. Downwards Vertical Attention Bias in Conversion Disorder vs Controls: A Pilot Study.

    Science.gov (United States)

    Gazit, Sivan; Elkana, Odelia; Dawidowicz, Liraz; Yeshayahu, Liel; Biran, Iftah

    Conversion disorder (CD) is a largely enigmatic disorder, one that requires a thorough ruling-out process. Prior research suggests that metaphors and conceptualization are rooted in physical experience, and that we interpret our affective world through metaphors. Spatial metaphors (interaction of affect and vertical space) are a prominent example of the grounding of metaphors. This is a relatively unpaved direction of research of CD. The present pilot study sought to explore this view by investigating the "healthy is up, sick is down" spatial metaphors (e.g., "fell ill" and "top shape") in patients with CD, examining the correlation between the processing of bodily-related words, CD, and vertical space. We hypothesized that patients with CD, who experience their bodies as ill, will demonstrate a downwards bias when processing bodily-related words; corresponding to the "healthy is up, sick is down" spatial metaphor. A total of 8 female patients (ages M-38.13 SD-10.44) and 42 female controls (ages M-36.4 SD-14.57) performed a visual attention task. Participants were asked to identify a spatial probe at the top or the bottom of a screen, following either a bodily related (e.g., arm) or non-bodily related (e.g., clock) prime word. As predicted, when processing bodily-related words, patients with CD demonstrated a downwards attention bias. Moreover, the higher the patient's level of somatization, the faster the patient detected lower (vs upper) spatial targets. This study suggests that the changed health paradigm of patients with CD is grounded in sensorimotor perception. Further research could propose new diagnostic and treatment options for CD. Copyright © 2017 The Academy of Psychosomatic Medicine. Published by Elsevier Inc. All rights reserved.

  14. Four-Wave Mixing of Gigawatt Power, Long-Wave Infrared Radiation in Gases and Semiconductors

    Science.gov (United States)

    Pigeon, Jeremy James

    The nonlinear optics of gigawatt power, 10 microm, 3 and 200 ps long pulses propagating in gases and semiconductors has been studied experimentally and numerically. In this work, the development of a high-repetition rate, picosecond, CO2 laser system has enabled experiments using peak intensities in the range of 1-10 GW/cm2, approximately one thousand times greater than previous nonlinear optics experiments in the long-wave infrared (LWIR) spectral region. The first measurements of the nonlinear refractive index of the atomic and molecular gases Kr, Xe, N2, O2 and the air at a wavelength near 10 microm were accomplished by studying the four-wave mixing (FWM) of dual-wavelength, 200 ps CO2 laser pulses. These measurements indicate that the nonlinearities of the diatomic molecules N2, O2 and the air are dominated by the molecular contribution to the nonlinear refractive index. Supercontinuum (SC) generation covering the infrared spectral range, from 2-20 microm, was realized by propagating 3 ps, 10 microm pulses in an approximately 7 cm long, Cr-doped GaAs crystal. Temporal measurements of the SC radiation show that pulse splitting accompanies the generation of such broadband light in GaAs. The propagation of 3 ps, 10 microm pulses in GaAs was studied numerically by solving the Generalized Nonlinear Schrodinger Equation (GNLSE). These simulations, combined with analytic estimates, were used to determine that stimulated Raman scattering combined with a modulational instability caused by the propagation of intense LWIR radiation in the negative group velocity dispersion region of GaAs are responsible for the SC generation process. The multiple FWM of a 106 GHz, 200 ps CO2 laser beat-wave propagating in GaAs was used to generate a broadband FWM spectrum that was compressed by the negative group velocity dispersion of GaAs and NaCl crystals to form trains of high-power, picosecond pulses at a wavelength near 10 microm. Experimental FWM spectra obtained using 165 and 882

  15. Effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells. II. In vitro PUVA inhibits degranulation of rat peritoneal mast cells induced by compound 48/80

    International Nuclear Information System (INIS)

    Toda, K.; Danno, K.; Tachibana, T.; Horio, T.

    1986-01-01

    Rat peritoneal mast cells incubated with a histamine liberator, compound 48/80, showed a significantly reduced capacity for releasing histamine following in vitro treatment with 0.1 micrograms/ml of 8-methoxypsoralen (8-MOP) plus 1-5 J/cm2 of long-wave ultraviolet (UVA) irradiation (PUVA). No remarkable inhibition in histamine release was observed in the cells treated with 8-MOP only. Irradiation with 5 J/cm2 of UVA alone exerted an inhibitory effect on histamine release, to a lesser extent than PUVA. PUVA irradiation did not bring any decrease in cell viability or any spontaneous release of histamine from irradiated cells as shown by phase-contrast microscopy and by histamine assay, respectively. These results suggest that PUVA treatment may cause a noncytotoxic disturbance at mast cell membranes or on surface receptors, leading to a decreased capacity for secreting chemical mediators

  16. A machine learning approach to estimation of downward solar radiation from satellite-derived data products: An application over a semi-arid ecosystem in the U.S.

    Science.gov (United States)

    Zhou, Qingtao; Flores, Alejandro; Glenn, Nancy F; Walters, Reggie; Han, Bangshuai

    2017-01-01

    Shortwave solar radiation is an important component of the surface energy balance and provides the principal source of energy for terrestrial ecosystems. This paper presents a machine learning approach in the form of a random forest (RF) model for estimating daily downward solar radiation flux at the land surface over complex terrain using MODIS (MODerate Resolution Imaging Spectroradiometer) remote sensing data. The model-building technique makes use of a unique network of 16 solar flux measurements in the semi-arid Reynolds Creek Experimental Watershed and Critical Zone Observatory, in southwest Idaho, USA. Based on a composite RF model built on daily observations from all 16 sites in the watershed, the model simulation of downward solar radiation matches well with the observation data (r2 = 0.96). To evaluate model performance, RF models were built from 12 of 16 sites selected at random and validated against the observations at the remaining four sites. Overall root mean square errors (RMSE), bias, and mean absolute error (MAE) are small (range: 37.17 W/m2-81.27 W/m2, -48.31 W/m2-15.67 W/m2, and 26.56 W/m2-63.77 W/m2, respectively). When extrapolated to the entire watershed, spatiotemporal patterns of solar flux are largely consistent with expected trends in this watershed. We also explored significant predictors of downward solar flux in order to reveal important properties and processes controlling downward solar radiation. Based on the composite RF model built on all 16 sites, the three most important predictors to estimate downward solar radiation include the black sky albedo (BSA) near infrared band (0.858 μm), BSA visible band (0.3-0.7 μm), and clear day coverage. This study has important implications for improving the ability to derive downward solar radiation through a fusion of multiple remote sensing datasets and can potentially capture spatiotemporally varying trends in solar radiation that is useful for land surface hydrologic and terrestrial

  17. Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

    Science.gov (United States)

    Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír

    2017-04-01

    More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands

  18. Simultaneous emissions of X-rays and microwaves from long laboratory sparks and downward lightning leaders

    Science.gov (United States)

    Montanya, J.; Oscar, V. D. V.; Tapia, F. F.

    2017-12-01

    radiation was detected before the return stroke. The microwave emissions in the first positive leader had lower amplitude but presented longer duration whereas the emissions in the three negative downward dart leaders were more impulsive. X-rays were detected in two of the three negative downward dart leaders.

  19. Ultra-Trace Chemical Sensing with Long-Wave Infrared Cavity-Enhanced Spectroscopic Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Taubman, Matthew S.; Myers, Tanya L.; Cannon, Bret D.; Williams, Richard M.; Schultz, John F.

    2003-02-20

    The infrared sensors task of Pacific Northwest National Laboratory's (PNNL's) Remote Spectroscopy Project (Task B of Project PL211) is focused on the science and technology of remote and in-situ spectroscopic chemical sensors for detecting proliferation and coun-tering terrorism. Missions to be addressed by remote chemical sensor development in-clude detecting proliferation of nuclear or chemical weapons, and providing warning of terrorist use of chemical weapons. Missions to be addressed by in-situ chemical sensor development include countering terrorism by screening luggage, personnel, and shipping containers for explosives, firearms, narcotics, chemical weapons, or chemical weapons residues, and mapping contaminated areas. The science and technology is also relevant to chemical weapons defense, air operations support, monitoring emissions from chemi-cal weapons destruction or industrial activities, law enforcement, medical diagnostics, and other applications. Sensors for most of these missions will require extreme chemical sensitivity and selectiv-ity because the signature chemicals of importance are expected to be present in low con-centrations or have low vapor pressures, and the ambient air is likely to contain pollutants or other chemicals with interfering spectra. Cavity-enhanced chemical sensors (CES) that draw air samples into optical cavities for laser-based interrogation of their chemical content promise real-time, in-situ chemical detection with extreme sensitivity to specified target molecules and superb immunity to spectral interference and other sources of noise. PNNL is developing CES based on quantum cascade (QC) lasers that operate in the mid-wave infrared (MWIR - 3 to 5 microns) and long-wave infrared (LWIR - 8 to 14 mi-crons), and CES based on telecommunications lasers operating in the short-wave infrared (SWIR - 1 to 2 microns). All three spectral regions are promising because smaller mo-lecular absorption cross sections in the SWIR

  20. Solute transport with time-variable flow paths during upward and downward flux in a heterogeneous unsaturated porous medium

    Science.gov (United States)

    Cremer, Clemens; Neuweiler, Insa; Bechtold, Michel; Vanderborght, Jan

    2014-05-01

    To acquire knowledge of solute transport through the unsaturated zone in the shallow subsurface is decisive to assess groundwater quality, nutrient cycling or to plan remediation strategies. The shallow subsurface is characterized by structural heterogeneity and strongly influenced by atmospheric conditions. This leads to changing flow directions, strong temporal changes in saturation and heterogeneous water fluxes during infiltration and evaporation events. Recent studies (e.g. Lehmann and Or, 2009; Bechtold et al.,2011) demonstrated the importance of lateral flow and solute transport during evaporation conditions (upward flux). The heterogeneous structure in these studies was constructed using two types of sand with strong material contrasts and arranged in parallel with a vertical orientation. Lateral transport and redistribution of solute from coarse to fine media was observed deeper in the soil column and from fine to coarse close to the soil surface. However, if boundary conditions are reversed due to precipitation, the flow field is not necessarily reversed in the same manner, resulting in entirely different transport patterns for downward and upward flow. Therefore, considering net-flow rates alone is misleading when describing transport under those conditions. In this contribution we analyze transport of a solute in the shallow subsurface to assess effects resulting from the temporal change of heterogeneous soil structures due to dynamic flow conditions. Two-dimensional numerical simulations of unsaturated flow and transport are conducted using a coupled finite volume and random walk particle tracking algorithm to quantify solute transport and leaching rates. Following previous studies (Lehmann and Or, 2009; Bechtold et al., 2011), the chosen domain is composed of two materials, coarse and fine sand, arranged in parallel with a vertical orientation. Hence, one sharp interface of strong material heterogeneity is induced. During evaporation both sands are

  1. Analysis of Tube Bank Heat Transfer In Downward Directed Foam Flow

    Directory of Open Access Journals (Sweden)

    Jonas Gylys

    2004-06-01

    Full Text Available Apparatus with the foam flow are suitable to use in different technologies like heat exchangers, food industry, chemical and oil processing industry. Statically stable liquid foam until now is used in technologic systems rather seldom. Although a usage of this type of foam as heat transfer agent in foam equipment has a number of advantages in comparison with one phase liquid equipment: small quantity of liquid is required, heat transfer rate is rather high, mass of equipment is much smaller, energy consumption for foam delivery into heat transfer zone is lower. The paper analyzes the peculiarities of heat transfer from distributed in staggered order and perpendicular to foam flow in channel of rectangular cross section tube bundle to the foam flow. It was estimated the dependence of mean gas velocity and volumetric void fraction of foam flow to heat transfer in downward foam flow. Significant difference of heat transfer intensity from front and back tubes of tube row in laminar foam flow was noticed. Dependence of heat transfer on flow velocity and volumetric void fraction of foam was confirmed and estimated by criterion equations.

  2. 'Downward control' of the mean meridional circulation and temperature distribution of the polar winter stratosphere

    Science.gov (United States)

    Garcia, Rolando R.; Boville, Byron A.

    1994-01-01

    According to the 'downward control' principle, the extratropical mean vertical velocity on a given pressure level is approximately proportional to the meridional gradient of the vertically integrated zonal force per unit mass exerted by waves above that level. In this paper, a simple numerical model that includes parameterizations of both planetary and gravity wave breaking is used to explore the influence of gravity wave breaking in the mesosphere on the mean meridional circulation and temperature distribution at lower levels in the polar winter stratosphere. The results of these calculations suggest that gravity wave drag in the mesosphere can affect the state of the polar winter stratosphere down to altitudes below 30 km. The effect is most important when planetary wave driving is relatively weak: that is, during southern winter and in early northern winter. In southern winter, downwelling weakens by a factor of 2 near the stratospause and by 20% at 30 km when gravity wave drag is not included in the calculations. As a consequence, temperatures decrease considerably throughout the polar winter stratosphere (over 20 K above 40 km and as much as 8 K at 30 km, where the effect is enhanced by the long radiative relaxation timescale). The polar winter states obtained when gravity wave drag is omitted in this simple model resemble the results of simulations with some general circulation models and suggest that some of the shortcomings of the latter may be due to a deficit in mesospheric momentum deposition by small-scale gravity waves.

  3. Flow Regime Identification of Co-Current Downward Two-Phase Flow With Neural Network Approach

    International Nuclear Information System (INIS)

    Hiroshi Goda; Seungjin Kim; Ye Mi; Finch, Joshua P.; Mamoru Ishii; Jennifer Uhle

    2002-01-01

    Flow regime identification for an adiabatic vertical co-current downward air-water two-phase flow in the 25.4 mm ID and the 50.8 mm ID round tubes was performed by employing an impedance void meter coupled with the neural network classification approach. This approach minimizes the subjective judgment in determining the flow regimes. The signals obtained by an impedance void meter were applied to train the self-organizing neural network to categorize these impedance signals into a certain number of groups. The characteristic parameters set into the neural network classification included the mean, standard deviation and skewness of impedance signals in the present experiment. The classification categories adopted in the present investigation were four widely accepted flow regimes, viz. bubbly, slug, churn-turbulent, and annular flows. These four flow regimes were recognized based upon the conventional flow visualization approach by a high-speed motion analyzer. The resulting flow regime maps classified by the neural network were compared with the results obtained through the flow visualization method, and consequently the efficiency of the neural network classification for flow regime identification was demonstrated. (authors)

  4. Correlation for downward melt penetration into a miscible low-density substrate

    International Nuclear Information System (INIS)

    Fang, L.J.; Cheung, F.B.; Pedersen, D.R.; Linehan, J.H.

    1984-01-01

    Downward penetration of a sacrificial bed material or a concrete basemat structure by an overlying layer of core melt resulting from a hypothetical core disruptive accident has been a major issue in post accident heat removal studies. One characteristic feature of this problem is that the solid substrate, when molten, is miscible with and lighter than the core melt so that the rate of penetration is strongly dependent upon the motion of natural convection in the melt layer driven by the density difference between the core melt and the molten substrate. This fundamentally interesting and technologically important problem has been investigated by a number of researchers. Significantly different melting rates, however, were observed in these studies. Questions concerning the occurrence of flow transition and its effect on melt penetration remain to be answered. To promote the understanding of the phenomena and to strengthen the data base of melt penetration, simulation experiments were conducted using various kinds of salt solutions (KI, NaCl, CaCl 2 , and MgCl 2 solutions) as the working fluid and an air-bubble-free ice slab as the solid substrate

  5. Reliability of levator scapulae index in subjects with and without scapular downward rotation syndrome.

    Science.gov (United States)

    Lee, Ji-Hyun; Cynn, Heon-Seock; Choi, Woo-Jeong; Jeong, Hyo-Jung; Yoon, Tae-Lim

    2016-05-01

    The objective of this study was to introduce levator scapulae (LS) measurement using a caliper and the levator scapulae index (LSI) and to investigate intra- and interrater reliability of the LSI in subjects with and without scapular downward rotation syndrome (SDRS). Two raters measured LS length twice in 38 subjects (19 with SDRS and 19 without SDRS). For reliability testing, intraclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated. Intrarater reliability analysis resulted with ICCs ranging from 0.94 to 0.98 in subjects with SDRS and 0.96 to 0.98 in subjects without SDRS. These results represented that intrarater reliability in both groups were excellent for measuring LS length with the LSI. Interrater reliability was good (ICC: 0.82) in subjects with SDRS; however, interrater reliability was moderate (ICC: 0.75) in subjects without SDRS. Additionally, SEM and MDC were 0.13% and 0.36% in subjects with SDRS and 0.35% and 0.97% in subjects without SDRS. In subjects with SDRS, low dispersion of the measurement errors and MDC were shown. This study suggested that the LSI is a reliable method to measure LS length and is more reliable for subjects with SDRS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Evaluation and comparison of the processing methods of airborne gravimetry concerning the errors effects on downward continuation results: Case studies in Louisiana (USA) and the Tibetan Plateau (China)

    DEFF Research Database (Denmark)

    Zhao, Qilong; Strykowski, Gabriel; Li, Jiancheng

    2017-01-01

    and the most extreme area of the world for this type of survey is the Tibetan Plateau. Since there are no high-accuracy surface gravity data available for this area, the above error minimization method involving the external gravity data cannot be used. We propose a semi-parametric downward continuation method...... in combination with regularization to suppress the systematic error effect and the random error effect in the Tibetan Plateau; i.e., without the use of the external high-accuracy gravity data. We use a Louisiana airborne gravity dataset from the USA National Oceanic and Atmospheric Administration (NOAA......) to demonstrate that the new method works effectively. Furthermore, and for the Tibetan Plateau we show that the numerical experiment is also successfully conducted using the synthetic Earth Gravitational Model 2008 (EGM08)-derived gravity data contaminated with the synthetic errors. The estimated systematic...

  7. Sensitivity of surface radiation budget to clouds over the Asian ...

    Indian Academy of Sciences (India)

    National Climate Centre, India Meteorological Department, Pune 400 005. ... down on the earth surface–atmosphere system also as an imbalance between surface netcloud ... the clouds produce more cooling effect in short-wave band than the warming effect in long-wave .... In the present study, we use the analysis method.

  8. Downward social comparison and subjective well-being in late life: the moderating role of perceived control.

    Science.gov (United States)

    Stewart, Tara L; Chipperfield, Judith G; Ruthig, Joelle C; Heckhausen, Jutta

    2013-01-01

    Drawing from Heckhausen and Schulz's Motivational Theory of Life-span Development, this study examined perceived control as a moderator of the protective relationship between downward social comparison and subjective well-being among older adults. Community-dwelling older adults (N = 97, 63% female, ages 79-97) were interviewed in their own homes at three time-points over a nine-year period. Interviews assessed older adults' perceived control over daily tasks, their use of downward social comparison in response to task restriction, and their subjective well-being. Regression analyses yielded a significant interaction between downward social comparison and perceived control for three subjective well-being outcomes: life satisfaction, perceived stress, and depressive symptoms. Follow-up analyses revealed that downward social comparison was associated with greater subjective well-being at low levels of perceived control; but was unrelated to subjective well-being at high levels of perceived control. These findings corroborate Heckhausen and Schulz's theorized goal-opportunity congruence premise and have implications for quality-of-life interventions to assist community-dwelling older adults.

  9. Distribution characteristics of interfacial parameter in downward gas-liquid two-phase flow in vertical circular tube

    International Nuclear Information System (INIS)

    Liu Guoqiang; Yan Changqi; Tian Daogui; Sun Licheng

    2014-01-01

    Experimental study was performed on distribution characteristics of interfacial parameters of downward gas-liquid flow in a vertical circular tube with the measurement by a two-sensor optical fiber probe. The test section is a circular pipe with the inner diameter of 50 mm and the length of 2000 mm. The superficial velocities of the gas and the liquid phases cover the ranges of 0.004-0.077 m/s and 0.43-0.71 m/s, respectively. The results show that the distributions of the interfacial parameters in downward bubbly flows are quite different from those in upward bubbly flows. For the case of upward flow, the parameters present the 'wall-peak' or 'core-peak' distributions, but for the case of downward flow, they show 'wall-peak' or 'wide-peak' distributions. The average value of void fraction in vertical downward flow is about 119.6%-145.0% larger than that in upward flow, and the interfacial area concentration is about 18.8%-82.5% larger than that in upward flow. The distribution of interfacial parameters shows an obvious tendency of uniformity. (authors)

  10. Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number

    KAUST Repository

    Yoon, Sung Hwan; Hu, Longhua; Fujita, Osamu

    2017-01-01

    by interaction between heat release and acoustic pressure fluctuations of the downward-propagating premixed flames in a tube to enhance conductive heat loss at the tube wall and radiative heat loss at the open end of the tube due to extended flame residence time

  11. Dropout and downward mobility in the educational career: An event-history analysis of ethnic schooling differences in the Netherlands

    NARCIS (Netherlands)

    Kalmijn, M.; Kraaykamp, G.L.M.

    2003-01-01

    While many aspects of educational careers have been examined ill the literature on ethnic minorities, such as truancy, turnover and grades, downward mobility has rarely been studied. Using data on more than 10,000 students who entered secondary school in The Netherlands in 1989, we develop an

  12. Dropout and Downward Mobility in the Educational Career : An Event-History Analysis of ethnic Schooling Differences in the Netherlands

    NARCIS (Netherlands)

    Kalmijn, M.; Kraaykamp, G.

    2003-01-01

    While many aspects of educational careers have been examined ill the literature on ethnic minorities, such as truancy, turnover and grades, downward mobility has rarely been studied. Using data on more than 10,000 students who entered secondary school in The Netherlands in 1989, we develop an

  13. Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

    Digital Repository Service at National Institute of Oceanography (India)

    Martin, P.; Loeff, M.M.R. van der.; Cassar, N.; Vandromme, P.; d'Ovidio, F.; Stemmann, L.; Rengarajan, R.; Soares, M.A.; Gonzalez, H.E.; Ebersbach, F.; Lampitt, R.S.; Sanders, R.; Barnett, B.A.; Smetacek, V.; Naqvi, S.W.A.

    A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux...

  14. Comparison of vehicle-mounted forward-looking polarimetric infrared and downward-looking infrared sensors for landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Schavemaker, J.G.M.; Jong, W. de; Schutte, K.

    2003-01-01

    This paper gives a comparison of two vehicle-mounted infrared systems for landmine detection. The first system is a down-ward looking standard infrared camera using processing methods developed within the EU project LOTUS. The second system is using a forward-looking polarimetric infrared camera.

  15. Measurements of the eigenfunction of reversed shear Alfvén eigenmodes that sweep downward in frequency

    International Nuclear Information System (INIS)

    Heidbrink, W. W.; Austin, M. E.; Spong, D. A.; Tobias, B. J.; Van Zeeland, M. A.

    2013-01-01

    Reversed shear Alfvén eigenmodes (RSAEs) usually sweep upward in frequency when the minimum value of the safety factor q min decreases in time. On rare occasions, RSAEs sweep downward prior to the upward sweep. Electron cyclotron emission measurements show that the radial eigenfunction during the downsweeping phase is similar to the eigenfunction of normal, upsweeping RSAEs

  16. Flow regime, void fraction and interfacial area transport and characteristics of co-current downward two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Lokanathan, Manojkumar [School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907-2088 (United States); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States)

    2016-10-15

    Highlights: • Downward flow regime maps and models were studied for 25.4 to 101.6 mm pipe diameters. • Effect of flow inlet on flow transition, void & interfacial area profile were studied. • Bubble void profiles were associated with the interfacial forces for downward flow. • Flow regime pressure drop and interfacial friction factor were studied. • The most applicable and accurate downward drift-flux correlation was determined. - Abstract: Downward two-phase flow is observed in light water reactor accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS) due to loss of feed water or a secondary pipe break. Hence, a comprehensive literature review has been performed for the co-current downward two-phase flow with information on the flow regime transitions and flow characteristics for each regime in the downward flow. The review compares the experimental data of the flow regime map and the current available transition models. Objectivity of the data varies on the method utilized as a certain degree of subjectivity is still present in the most objective method. Nevertheless, experimental data through subjective methods such as direct visualization or analysis of a wire mesh sensor (WMS) data were still studied in this review. Despite the wide range of flow regime data for numerous pipe sizes, a consensus was not reached for the effect of pipe sizes on flow regime transition. However, it is known that a larger pipe results in greater degree of coalescence at lower gas flow rates (Hibiki et al., 2004). The introduction of a flow straightener at the inlet led to less coring and fluid rotation and inevitably, reduced bubble coalescence. This also resulted in the disappearance of the kinematic shock wave phenomenon, contrary to an inlet without a flow straightener. The effect of flow inlet, flow location, pipe diameter and bubble interfacial forces on the radial distribution as well as bubble coalescence and breakup rate

  17. Downward carbon transport in a 2000-year rice paddy soil chronosequence traced by radiocarbon measurements

    Energy Technology Data Exchange (ETDEWEB)

    Braeuer, T., E-mail: tbraeuer@leibniz.uni-kiel.de [Leibniz-Laboratory, Christian-Albrechts-University, Kiel (Germany); Grootes, P.M.; Nadeau, M.-J.; Andersen, N. [Leibniz-Laboratory, Christian-Albrechts-University, Kiel (Germany)

    2013-01-15

    Paddy and non-paddy soils from a chronosequence of 50-2000 years of agricultural use, developed on former estuarine sediments of the Yangtze River, were sampled near Cixi, Zhejiang Province, China, in the framework of the Research Unit 'Biogeochemistry of paddy soil evolution' of the German Research Foundation (DFG). In addition samples of Yangtze River estuarine sediments were obtained. The parent sediment shows a fairly homogeneous composition with ca. 0.3% TOC and a {sup 14}C concentration of ca. 50 pMC. After being diked-in, gradients in soil organic carbon and {sup 14}C concentration develop under the influence of vegetation and cultivation. In the non-paddy soil, a {sup 14}C gradient with concentration decreasing with increasing depth from modern (>100 pMC) to original sediment values around 50 pMC is already established after 50 years and can also be observed in the older sites. In contrast, the 50 years old paddy soil shows organic carbon and {sup 14}C enrichment only in the A-horizon and a nearly constant TOC and {sup 14}C stock of original sediment below the plough pan. To test the basic approach that the soil profile development started on homogeneous sediment, an isotope and mass balance calculation was used. The results show a quite similar age composition of different sample sites. Paddy rice cultivation quickly leads to a dense plough pan, which seriously reduces, but not totally prevents, downward transport of organic matter. The equilibrium times for TOC and {sup 14}C in paddy soil profiles are short (decades) in the topsoil and in the order of centuries in the subsoil, underlining the dynamic character of soil organic carbon.

  18. Downward carbon transport in a 2000-year rice paddy soil chronosequence traced by radiocarbon measurements

    International Nuclear Information System (INIS)

    Bräuer, T.; Grootes, P.M.; Nadeau, M.-J.; Andersen, N.

    2013-01-01

    Paddy and non-paddy soils from a chronosequence of 50–2000 years of agricultural use, developed on former estuarine sediments of the Yangtze River, were sampled near Cixi, Zhejiang Province, China, in the framework of the Research Unit “Biogeochemistry of paddy soil evolution” of the German Research Foundation (DFG). In addition samples of Yangtze River estuarine sediments were obtained. The parent sediment shows a fairly homogeneous composition with ca. 0.3% TOC and a 14 C concentration of ca. 50 pMC. After being diked-in, gradients in soil organic carbon and 14 C concentration develop under the influence of vegetation and cultivation. In the non-paddy soil, a 14 C gradient with concentration decreasing with increasing depth from modern (>100 pMC) to original sediment values around 50 pMC is already established after 50 years and can also be observed in the older sites. In contrast, the 50 years old paddy soil shows organic carbon and 14 C enrichment only in the A-horizon and a nearly constant TOC and 14 C stock of original sediment below the plough pan. To test the basic approach that the soil profile development started on homogeneous sediment, an isotope and mass balance calculation was used. The results show a quite similar age composition of different sample sites. Paddy rice cultivation quickly leads to a dense plough pan, which seriously reduces, but not totally prevents, downward transport of organic matter. The equilibrium times for TOC and 14 C in paddy soil profiles are short (decades) in the topsoil and in the order of centuries in the subsoil, underlining the dynamic character of soil organic carbon.

  19. Natural convection in a water tank with a heated horizontal plate facing downward

    International Nuclear Information System (INIS)

    Yang, Sun Kyoo; Jung, Moon Kee; Helmut Hoffmann

    1995-01-01

    Experimental and computational studies were carried out to investigate the natural convection of the single phase flow in a tank with a heated horizontal plate facing downward. This is a simplified model for investigations of the influence of a core melt at the bottom of a reactor vessel on the thermal hydraulic behavior in a water filled cavity surrounding the vessel. In this case the vessel is simulated by a hexahedron insulated box with a heated plate horizontally mounted at the bottom of the box. The box with the heated plate is installed in a water filled hexahedron tank. Coolers are immersed in the U-type water volume between the box and the tank. Although the multicomponent flows exist more probably below the heated plate in reality, present study concentrates on the single phase flow in a first step prior to investigating the complicated multicomponent thermal hydraulic phenomena. In the present study, in order to get a better understanding for the natural convection characteristics below the heated plate, the velocity and temperature are measured by LDA(Laser Doppler Anemometry) and thermocouples, respectively. And flow fields are visualized by taking pictures of the flow region with suspended particles. The results show the occurrence of a very effective circulation of the fluid in the whole flow area as the heater and coolers are put into operation. In the remote region below the heated plate the flow is nearly stagnant, and a remarkable temperature stratification can be observed with very thin thermal boundary. Analytical predictions using the FLUTAN code show a reasonable matching of the measured velocity fields. 18 figs., 2 tabs., 18 refs. (Author)

  20. Tracers confirm downward mixing of Tyrrhenian Sea upper waters associated with the Eastern Mediterranean Transient

    Directory of Open Access Journals (Sweden)

    W. Roether

    2011-01-01

    Full Text Available Observations of tritium and 3He in the Tyrrhenian Sea, 1987–2009, confirm the enhanced vertical mixing of intermediate waters into the deep waters that has been noted and associated with the Eastern Mediterranean Transient in previous studies. Our evidence for the mixing rests on increasing tracer concentrations in the Tyrrhenian deep waters, accompanied by decreases in the upper waters, which are supplied from the Eastern Mediterranean. The downward transfer is particularly evident between 1987 and 1997. Later on, information partly rests on increasing tritium-3He ages; here we correct the observed 3He for contributions released from the ocean floor. The Tyrrhenian tracer distributions are fully compatible with data upstream of the Sicily Strait and in the Western Mediterranean. The tracer data show that mixing reached to the bottom and confirm a cyclonic nature of the deep water circulation in the Tyrrhenian. They furthermore indicate that horizontal homogenization of the deep waters occurs on a time scale of roughly 5 years. Various features point to a reduced impact of Western Mediterranean Deep Water (WMDW in the Tyrrhenian during the enhanced-mixing period. This is an important finding because it implies less upward mixing of WMDW, which has been named a major process to enable the WMDW to leave the Mediterranean via the Gibraltar Strait. On the other hand, the TDW outflow for several years represented a major influx of enhanced salinity and density waters into the deep-water range of the Western Mediterranean.

  1. Photometric and fluorometric continuous kinetic assay of acid phosphatases with new substrates possessing longwave absorption and emission maxima.

    Science.gov (United States)

    Koller, E; Wolfbeis, O S

    1984-11-15

    A direct and continuous kinetic method for the photometric and fluorometric determination of various acid phosphatases is described. It is based on new coumarin-derived phosphates, which after enzymatic hydrolysis undergo dissociation to form intensely colored and strongly fluorescent phenolate anions. The latter have absorption maxima ranging from 385 to 505 nm, and fluorescence maxima between 470 and 595 nm. The new substrates were compared with respect to their rate of enzymatic hydrolysis, optimum pH, and detection limits of acid phosphatase from potato and wheat germ. Detection limits of 0.001 unit/ml were found by photometry, and as low as 0.00006 unit/ml by fluorometry. The principal advantages of the new substrates over existing ones are longwave absorptions and emissions, large Stokes shifts, and the low pKa values of the corresponding phenols, thus allowing a direct and continuous assay of acid phosphatase even in weakly acidic solutions.

  2. Comparative analysis of different approaches to the computation of long-wave radiation balance of water air systems

    International Nuclear Information System (INIS)

    Zhukovskii, K.; Nourani, Y.; Monte, L.

    1999-01-01

    In the present paper, the net long-wave radiation balance of the water-air environmental systems is analysed on the base of several semi-empirical approaches. Various theoretical models of infrared atmospheric radiation are reviewed. Factors, affecting their behavior are considered. Special attention is paid to physical conditions under which those models are applicable. Atmospheric and net infrared radiation fluxes are computed and compared under clear and cloudy sky. Results are presented in graphical form. Conclusions are made on the applicability of models considered for evaluating infrared radiation fluxes in environmental conditions of Central Italy. On the base of present analysis Anderson's model is chosen for future calculations of heat budget of lakes in Central Italy [it

  3. Effect of long-wave ultraviolet light on the lens. I. Model systems for detecting and measuring effect on the lens in vitro

    International Nuclear Information System (INIS)

    Kuck, J.F.R. Jr.

    1976-01-01

    Rat, mouse, and chick lenses incubated with 3-aminotriazole under long-wave ultraviolet (UV) show reduced accumulation and incorporation of leucine and a loss of glutathione. The effect on leucine incorporation is strikingly enhanced when capsule-epithelium pools are incubated. The procedure may identify photosensitizers or metabolic inhibitors which are cataractogenic when acting in conjunction with UV

  4. Observation of The Top of The Atmosphere Outgoing Longwave Radiation Using The Geostationary Earth Radiation Budget Sensor

    Science.gov (United States)

    Spencer, G.; Llewellyn-Jones, D.

    In the summer of 2002 the Meteosat Second Generation (MSG) satellite is due to be launched. On board the MSG satellite is the Geostationary Earth Radiation Budget (GERB) sensor. This is a new radiometer that will be able to observe and measure the outgoing longwave radiation from the top of the atmosphere for the whole ob- served Earth disc, due to its unique position in geostationary orbit. Every 15 minutes the GERB sensor will make a full Earth disc observation, centred on the Greenwich meridian. Thus, the GERB sensor will provide unprecedented coupled temporal and spatial resolution of the outgoing longwave radiation (4.0 to 30.0 microns), by first measuring the broadband radiation (0.32 to 30.0 microns) and then subtracting the measured reflected shortwave solar radiation (0.32 to 4.0 microns), from the earth- atmosphere system. The GERB sensor is able to make measurements to within an accuracy of 1 W/sq. m. A forward model is being developed at Leicester to simulate the data from the GERB sensor for representative geophysical scenes and to investigate key parameters and processes that will affect the top of the atmosphere signal. At the heart of this model is a line-by-line radiative transfer model, the Oxford Reference Forward Model (RFM) that is to be used with model atmospheres generated from ECMWF analysis data. When MSG is launched, cloud data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI), also on board, is to be used in conjunction with GERB data.

  5. Radiometric analysis of the longwave infrared channel of the Thematic Mapper on LANDSAT 4 and 5

    Science.gov (United States)

    Schott, John R.; Volchok, William J.; Biegel, Joseph D.

    1986-01-01

    The first objective was to evaluate the postlaunch radiometric calibration of the LANDSAT Thematic Mapper (TM) band 6 data. The second objective was to determine to what extent surface temperatures could be computed from the TM and 6 data using atmospheric propagation models. To accomplish this, ground truth data were compared to a single TM-4 band 6 data set. This comparison indicated satisfactory agreement over a narrow temperature range. The atmospheric propagation model (modified LOWTRAN 5A) was used to predict surface temperature values based on the radiance at the spacecraft. The aircraft data were calibrated using a multi-altitude profile calibration technique which had been extensively tested in previous studies. This aircraft calibration permitted measurement of surface temperatures based on the radiance reaching the aircraft. When these temperature values are evaluated, an error in the satellite's ability to predict surface temperatures can be estimated. This study indicated that by carefully accounting for various sensor calibration and atmospheric propagation effects, and expected error (1 standard deviation) in surface temperature would be 0.9 K. This assumes no error in surface emissivity and no sampling error due to target location. These results indicate that the satellite calibration is within nominal limits to within this study's ability to measure error.

  6. Study of the influence of water properties dependency with the temperature in a laminar downward flow between parallel flat plates

    International Nuclear Information System (INIS)

    Delmastro, Dario F.; Chasseur, A.F.; Garcia, Juan C.

    2007-01-01

    In this work we develop a model that contemplates stationary completely developed laminar downward flow between flat parallel plates with uniform and constant heat fluxes. The Boussinesq approach is used in the momentum equation, taking into account the change of the density with the temperature only in the gravitational term. The system is at atmospheric pressure and the dependencies of the density and the thermal conductivity with the temperature are also considered. The velocity and temperature profiles, the friction factor, the heat transfer coefficient and the Nusselt Number are calculated, for different flow rates and heating powers. The results allow to obtain some conclusions that can be of interest in the study of research reactors with forced downward refrigeration and flat plate fuels, although these calculations do not exactly represent the real behavior inside these channels. (author) [es

  7. The Downward Causality and the Hard Problem of Consciousness or Why Computer Programs Do not Work in the Dark

    Directory of Open Access Journals (Sweden)

    Boldachev Alexander

    2015-01-01

    Full Text Available Any low-level processes, the sequence of chemical interactions in a living cell, muscle cellular activity, processor commands or neuron interaction, is possible only if there is a downward causality, only due to uniting and controlling power of the highest level. Therefore, there is no special “hard problem of consciousness”, i.e. the problem of relation of ostensibly purely biological materiality and non-causal mentality - we have only the single philosophical problem of relation between the upward and downward causalities, the problem of interrelation between hierarchic levels of existence. It is necessary to conclude that the problem of determinacy of chemical processes by the biological ones and the problem of neuron interactions caused by consciousness are of one nature and must have one solution.

  8. A simple way of characterizing X-ray downwards-deflecting mirror-bender assemblies using the long trace profiler

    International Nuclear Information System (INIS)

    Assoufid, L.; Her, P.

    1999-01-01

    A simple device composed of a modular double-pentaprism system that enables the long trace profiler (LTP) to measure mirrors in nonconventional ways, i.e., in the vertical-downward and sideways positions, has been devised and implemented in the Advanced Photon Source (APS) long trace profiler (LTP II). The systems is very useful in calibrating mirror-bender assemblies. This paper describes the system and gives results of measurements performed with it on a mirror used at the APS

  9. On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

    Science.gov (United States)

    Bagiya, Mala S.; Vichare, Geeta; Sinha, A. K.; Sripathi, S.

    2018-02-01

    During quiet period, the nocturnal equatorial ionospheric plasma drifts eastward in the zonal direction and downward in the vertical direction. This quiet time drift pattern could be understood through dynamo processes in the nighttime equatorial ionosphere. The present case study reports the nocturnal simultaneous occurrence of the vertically downward and zonally westward plasma drifts over the Indian latitudes during the geomagnetic storm of 17 March 2015. After 17:00 UT ( 22:10 local time), the vertical plasma drift became downward and coincided with the westward zonal drift, a rarely observed feature of low latitude plasma drifts. The vertical drift turned upward after 18:00 UT, while the zonal drift became eastward. We mainly emphasize here the distinct bipolar type variations of vertical and zonal plasma drifts observed around 18:00 UT. We explain the vertical plasma drift in terms of the competing effects between the storm time prompt penetration and disturbance dynamo electric fields. Whereas, the westward drift is attributed to the storm time local electrodynamical changes mainly through the disturbance dynamo field in addition to the vertical Pedersen current arising from the spatial (longitudinal) gradient of the field aligned Pedersen conductivity.

  10. Unexpected high 35S concentration revealing strong downward transport of stratospheric air during the monsoon transitional period in East Asia

    Science.gov (United States)

    Lin, Mang; Zhang, Zhisheng; Su, Lin; Su, Binbin; Liu, Lanzhong; Tao, Jun; Fung, Jimmy C. H.; Thiemens, Mark H.

    2016-03-01

    October is the monsoon transitional period in East Asia (EA) involving a series of synoptic activities that may enhance the downward transport of stratospheric air to the planetary boundary layer (PBL). Here we use cosmogenic 35S in sulfate aerosols (35SO42-) as a tracer for air masses originating from the stratosphere and transported downward to quantify these mixing processes. From 1 year 35SO42- measurements (March 2014 to February 2015) at a background station in EA we find remarkably enhanced 35SO42- concentration (3150 atoms m-3) in October, the highest value ever reported for natural sulfate aerosols. A four-box 1-D model and meteorological analysis reveal that strong downward transport from the free troposphere is a vital process entraining aged stratospheric air masses to the PBL. The aged stratospheric masses are accumulated in the PBL, accelerating the SO2 transformation to SO42-. Implications for the tropospheric O3 budget and the CO2 biogeochemical cycle are discussed.

  11. Are insecure jobs as bad for mental health and occupational commitment as unemployment? Equal threat or downward spiral

    Directory of Open Access Journals (Sweden)

    Kathleen Otto

    2014-01-01

    Full Text Available We investigated the significance of unemployment and job insecurity for mental health (self-esteem; life satisfaction and occupational commitment (occupational self-efficacy; affective occupational commitment comparing the "equal threat" assumption with the "downward spiral" assumption. Whereas the equal threat model suggests that unemployment and (perceived insecure employment are similarly threatening phenomena, the downward spiral model assumes that there might be a spectrum of employment insecurity, ranging from secure employment to long-term unemployment, that is associated with decreasing mental health and occupational commitment. Controlling for socio-demographic background variables and personality traits, results of ANCOVAs, in which we distinguished between workers who were (more or less securely employed and those who were either insecurely employed or short- or long-term unemployed revealed that the insecurely employed workers were no better off than those who were (short-term unemployed - in line with the equal threat hypothesis. Only for occupational self-efficacy did we find some support for the downward spiral model.

  12. Disappearance of the laue spots of the downward X-ray diffraction and huge recoil Thomson scattering in solid helium as some prominent peculiarities of a quantum crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Tetsuo

    1996-02-01

    In topographs of the downward X-ray diffraction, no Laue spots could be observed using a horizontally thin line-focussed beam. The disappearance of the Laue spots by the downward X-ray diffraction could be explained by two main factors besides a synergistic effect of the smallness of the atomic-scattering factors, the absorption coefficients, the densities etc. One is that the downward X-ray diffraction is completely inelastic scattering, and, as a result, diffracted X-ray beams may become entirely diffuse scattering. The other is that the great difference in the linear scatterer density between the forward and downward directions resulted from the fact that the irradiation of a line-focussed X-ray beam to take section topographs weakens the downward X-ray diffraction. The main reason is not due to the zero-point vibration. (J.P.N.).

  13. Disappearance of the laue spots of the downward X-ray diffraction and huge recoil Thomson scattering in solid helium as some prominent peculiarities of a quantum crystal

    International Nuclear Information System (INIS)

    Nakajima, Tetsuo.

    1996-02-01

    In topographs of the downward X-ray diffraction, no Laue spots could be observed using a horizontally thin line-focussed beam. The disappearance of the Laue spots by the downward X-ray diffraction could be explained by two main factors besides a synergistic effect of the smallness of the atomic-scattering factors, the absorption coefficients, the densities etc. One is that the downward X-ray diffraction is completely inelastic scattering, and, as a result, diffracted X-ray beams may become entirely diffuse scattering. The other is that the great difference in the linear scatterer density between the forward and downward directions resulted from the fact that the irradiation of a line-focussed X-ray beam to take section topographs weakens the downward X-ray diffraction. The main reason is not due to the zero-point vibration. (J.P.N.)

  14. Impact of external longwave radiation on optimum insulation thickness in Tunisian building roofs based on a dynamic analytical model

    International Nuclear Information System (INIS)

    Daouas, Naouel

    2016-01-01

    Highlights: • An efficient tool is proposed for a rigorous energy analysis of building envelope. • The longwave radiation has an important impact on the energy requirements. • Optimum insulation thickness for roofs is rigorously determined in a cost analysis. • The present method is more accurate than the sol–air degree hours method. • The proposed model is applicable to the study of the efficiency of cool roofs. - Abstract: In Tunisia, the building sector is considered as a major issue of energy consumption. A special attention should be drawn to improve the thermal quality of the building envelope with real consideration of the Tunisian climate specificity. One of the most effective measures is the roof insulation. Therefore, the present study is concerned with the determination of the optimum insulation thickness and the resulting energy savings and payback period for two typical roof structures and two types of insulation materials. An efficient analytical dynamic model based on the Complex Finite Fourier Transform (CFFT) is proposed and validated in order to handle the nonlinear longwave radiation (LWR) exchange with the sky. This model provides a short computational time solution of the transient heat transfer through multilayer roofs, which could be a good alternative to some numerical methods. Both heating and cooling annual loads are rigorously estimated and used as inputs to a life-cycle cost analysis. Among the studied cases, the most economical one is the hollow terracotta-based roof insulated with rock wool, where the optimum insulation thickness is estimated to be 7.9 cm, with a payback period of 6.06 years and energy savings up to 58.06% of the cost of energy consumed without insulation. The impact of the LWR exchange component is quantified and the results show its important effect on the annual transmission loads and, consequently, on optimum insulation thickness. A sensitivity analysis shows the efficiency of cool roofs in the Tunisian

  15. Advances in low-cost long-wave infrared polymer windows

    Science.gov (United States)

    Weimer, Wayne A.; Klocek, Paul

    1999-07-01

    Recent improvements in engineered polymeric material compositions and advances in processing methodologies developed and patented at Raytheon Systems Company have produced long wave IR windows at exceptionally low costs. These UV stabilized, high strength windows incorporating subwavelength structured antireflection surfaces are enabling IR imaging systems to penetrate commercial markets and will reduce the cost of systems delivered to the military. The optical and mechanical properties of these windows will be discussed in detail with reference to the short and long-term impact on military IR imaging systems.

  16. Progress in Understanding Land-Surface-Atmosphere Coupling from LBA Research

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2010-06-01

    Full Text Available LBA research has deepened our understanding of the role of soil water storage, clouds and aerosols in land-atmosphere coupling. We show how the reformulation of cloud forcing in terms of an effective cloud albedo per unit area of surface gives a useful measure of the role of clouds in the surface energy budget over the Amazon. We show that the diurnal temperature range has a quasi-linear relation to the daily mean longwave cooling; and to effective cloud albedo because of the tight coupling between the near-surface climate, the boundary layer and the cloud field. The coupling of surface and atmospheric processes is critical to the seasonal cycle: deep forest rooting systems make water available throughout the year, whereas in the dry season the shortwave cloud forcing is reduced by regional scale subsidence, so that more light is available for photosynthesis. At sites with an annual precipitation above 1900 mm and a dry season length less than 4 months, evaporation rates increased in the dry season, coincident with increased radiation. In contrast, ecosystems with precipitation less than 1700 mm and a longer dry season showed clear evidence of reduced evaporation in the dry season coming from water stress. In all these sites, the seasonal variation of the effective cloud albedo is a major factor in determining the surface available energy. Dry season fires add substantial aerosol to the atmosphere. Aerosol scattering and absorption both reduce the total downward surface radiative flux, but increase the diffuse/direct flux ratio, which increases photosynthetic efficiency. Convective plumes produced by fires enhance the vertical transport of aerosols over the Amazon, and effectively inject smoke aerosol and gases directly into the middle troposphere with substantial impacts on mid- tropospheric dispersion. In the rainy season in Rondônia, convection in low-level westerly flows with low aerosol content resembles oceanic convection with

  17. Nonlinear interaction between a pair of oblique modes in a supersonic mixing layer: Long-wave limit

    Science.gov (United States)

    Balsa, Thomas F.; Gartside, James

    1995-01-01

    The nonlinear interaction between a pair of symmetric, oblique, and spatial instability modes is studied in the long-wave limit using asymptotic methods. The base flow is taken to be a supersonic mixing layer whose Mach number is such that the corresponding vortex sheet is marginally stable according to Miles' criterion. It is shown that the amplitude of the mode obeys a nonlinear integro-differential equation. Numerical solutions of this equation show that, when the obliqueness angle is less than pi/4, the effect of the nonlinearity is to enhance the growth rate of the instability. The solution terminates in a singularity at a finite streamwise location. This result is reminiscent of that obtained in the vicinity of the neutral point by other authors in several different types of flows. On the other hand, when the obliqueness angle is more than pi/4, the streamwise development of the amplitude is characterized by a series of modulations. This arises from the fact that the nonlinear term in the amplitude equation may be either stabilizing or destabilizing, depending on the value of the streamwise coordinate. However, even in this case the amplitude of the disturbance increases, though not as rapidly as in the case for which the angle is less than pi/4. Quite generally then, the nonlinear interaction between two oblique modes in a supersonic mixing layer enhances the growth of the disturbance.

  18. Long-wave analysis and control of the viscous Rayleigh-Taylor instability with electric fields

    Science.gov (United States)

    Cimpeanu, Radu; Anderson, Thomas; Petropoulos, Peter; Papageorgiou, Demetrios

    2016-11-01

    We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a solid surface in the presence of a horizontally acting electric field. The competition between gravity, surface tension and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semi-spectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations and assess the accuracy of the obtained solutions when varying the electric field strength from zero up to the point when complete stabilization at the target finite wavelengths occurs. We employ DNS to examine the limitations of the asymptotically derived behavior in the context of increasing liquid film heights, with agreement found to be excellent even beyond the target lengthscales. Regimes in which the thin film assumption is no longer valid and droplet pinch-off occurs are then analyzed. Finally, the asymptotic and computational approaches are used in conjunction to identify efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

  19. A comparison of ground reaction force components according to the foothold heights in 16-t truck during downward step.

    Science.gov (United States)

    Hyun, Seung-Hyun; Ryew, Che-Cheong

    2017-12-01

    The aim of this study is to compare and analyze the components of ground reaction force (GRF) relative to the foothold heights during downward step of 16-t truck. Adult males (n= 10) jumped downward from each 1st, 2nd, 3rd foothold step and driver's seat orderly using hand rail. Sampling rate of force components of 3 axis (medial-lateral [ML] GRF, anterior-posterior [AP] GRF, peak vertical force [PVF]), variables (COPx, COPy, COP area) of center of pressure (COP), loading rate, and stability index (ML, AP, vertical, and dynamic postural stability index [DPSI]) processed from GRF system was cut off at 1,000 Hz. and variables was processed with repeated one-way analysis of variance. AP GRF, PVF and loading rate showed higher value in case of not used hand rail than that used hand rail in all 1st, 2nd, and 3rd of foothold step. DPSI showed more lowered stability in order of 2nd, 3rd step than 1st foothold step used with hand rail, of which showed lowest stability from driver's seat. COPx, COPy, and COP area showed higher value in case of 2nd and 3rd than that of 1st of foothold step, and showed lowest stability from driver's seat. It is more desirable for cargo truck driver to utilize an available hand rail in order of 3rd, 2nd, and 1st of foothold step than downward stepping directly, thus by which may results in decrease of falling injuries and minimization of impulsive force transferring to muscular-skeletal system.

  20. A 19m Deep Well – a Downward Thermal Diffusion Cloud Chamber?

    OpenAIRE

    Holub, R.F.

    2013-01-01

    An unusual phenomenon, first observed on a clear summer day after several rainy days, were droplets constantly hitting the water surface in a 19 m deep and 2.4 m diameter water well. This droplet formation was occurring during the night as well. Since the droplet formation was near continuous, we called it “the eternal rain”. The water well is about 230 years old and located in the Benedictine monastery in Broumov, Czech Republic.

  1. Mixed convection heat transfer to carbon dioxide flowing upward and downward in a vertical tube and an annular channel

    International Nuclear Information System (INIS)

    Bae, Yoon Y.

    2011-01-01

    Highlights: → Experimental results of heat transfer at a supercritical pressure for a tube with an inner diameter of 4.57 mm and a corresponding annular channel (8 mm x 10 mm, 1 mm gap) were compared each other. → Effect of various parameters such as pressure, flow direction, diameter, channel shape, was investigated. → Existing correlation for supercritical heat transfer were evaluated against the experimental data. → Some unusual characteristics of supercritical heat transfer, such as overshoot and non-monotonic behavior against buoyancy parameter, were discussed. → New correlations were proposed based on the experimental data. - Abstract: This paper addresses three main subjects in supercritical heat transfer: (1) difference in thermal characteristics between upward and downward flows; (2) effect of simulating flow channel shape; (3) evaluation of the existing supercritical heat transfer correlations. To achieve the objectives, a series of experiments was carried out with CO 2 flowing upward and downward in a circular tube with an inner diameter of 4.57 mm and an annular channel created between a tube with an inner diameter of 10 mm and a heater rod with an outer diameter of 8 mm. The working fluid, CO 2 , has been regarded as an appropriate modeling fluid for water, primarily because of their similarity in property variations against reduced temperatures. The mass flux ranged from 400 to 1200 kg/m 2 s. The heat flux was varied between 30 and 140 kW/m 2 so that the pseudo-critical point was located in the middle of the heated section at a given mass flux. The measurements were made at a pressure of 8.12 MPa, which corresponds to 110% of the critical pressure of CO 2 . The difference between the upward and downward flows was observed clearly. The heat transfer deterioration was observed in the downward flow through an annular subchannel over the region beyond the critical point. Several well-known correlations were evaluated against the experimental

  2. Study of Volcanic Activity at Different Time Scales Using Hypertemporal Land Surface Temperature Data

    NARCIS (Netherlands)

    Pavlidou, Efthymia; Hecker, Chris; van der Werff, Harald; van der Meijder, Mark

    2017-01-01

    We apply a method for detecting subtle spatiotemporal signal fluctuations to monitor volcanic activity. Whereas midwave infrared data are commonly used for volcanic hot spot detection, our approach utilizes hypertemporal longwave infrared-based land surface temperature (LST) data. Using LST data of

  3. Climatic responses to the shortwave and longwave direct radiative effects of sea salt aerosol in present day and the last glacial maximum

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Xu [Chinese Academy of Sciences (CAS), Climate Change Research Center (CCRC), Beijing (China); Chinese Academy of Sciences (CAS), Nansen-Zhu International Research Center, Institute of Atmospheric Physics (IAP), Beijing (China); Harvard University, School of Engineering and Applied Sciences, Cambridge, MA (United States); Liao, Hong [Chinese Academy of Sciences (CAS), State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), P.O. Box 9804, Beijing (China)

    2012-12-15

    We examine the climatic responses to the shortwave (SW) and longwave (LW) direct radiative effects (RE) of sea salt aerosol in present day and the last glacial maximum (LGM) using a general circulation model with online simulation of sea salt cycle. The 30-year control simulation predicts a present-day annual emission of sea salt of 4,253 Tg and a global burden of 8.1 Tg for the particles with dry radii smaller than 10 {mu}m. Predicted annual and global mean SW and LW REs of sea salt are, respectively, -1.06 and +0.14 W m{sup -2} at the top of atmosphere (TOA), and -1.10 and +0.54 W m{sup -2} at the surface. The LW warming of sea salt is found to decrease with altitude, which leads to a stronger net sea salt cooling in the upper troposphere. The changes in global mean air temperature by the present-day sea salt are simulated to be -0.55, -0.63, -0.86, and -0.91 K at the surface, 850, 500a, and 200 hPa, respectively. The emission of sea salt at the LGM is estimated to be 4,075 Tg year{sup -1}. Relative to present day, the LGM sea salt emission is higher by about 18% over the tropical and subtropical oceans, and is lower by about 35% in the mid- and high-latitudes in both hemispheres because of the expansion of sea ice. As a result of the weakened LGM water cycle, the LGM annual and global mean burden of sea salt is predicted to be higher by 4% as compared to the present-day value. Compared with the climatic effect of sea salt in present day, the sea-salt-induced reductions in surface air temperature at the LGM have similar magnitude in the tropics but are weakened by about 0.18 and 0.14 K in the high latitudes of the Southern and Northern Hemispheres, respectively. We also perform a sensitivity study to explore the upper limit of the climatic effect of the LGM sea salt. We assume an across-the-board 30% increase in the glacial wind speed and consider sea salt emissions over sea ice, so that the model can reproduce the ratio of sea salt deposition between the LGM and

  4. PREDICTION METRICS FOR CHEMICAL DETECTION IN LONG-WAVE INFRARED HYPERSPECTRAL IMAGERY

    Energy Technology Data Exchange (ETDEWEB)

    Chilton, M.; Walsh, S.J.; Daly, D.S.

    2009-01-01

    Natural and man-made chemical processes generate gaseous plumes that may be detected by hyperspectral imaging, which produces a matrix of spectra affected by the chemical constituents of the plume, the atmosphere, the bounding background surface and instrument noise. A physics-based model of observed radiance shows that high chemical absorbance and low background emissivity result in a larger chemical signature. Using simulated hyperspectral imagery, this study investigated two metrics which exploited this relationship. The objective was to explore how well the chosen metrics predicted when a chemical would be more easily detected when comparing one background type to another. The two predictor metrics correctly rank ordered the backgrounds for about 94% of the chemicals tested as compared to the background rank orders from Whitened Matched Filtering (a detection algorithm) of the simulated spectra. These results suggest that the metrics provide a reasonable summary of how the background emissivity and chemical absorbance interact to produce the at-sensor chemical signal. This study suggests that similarly effective predictors that account for more general physical conditions may be derived.

  5. Evaluation of Haney-Type Surface Thermal Boundary Conditions Using a Coupled Atmosphere and Ocean Model

    National Research Council Canada - National Science Library

    Chu, Peter C; Chen, Yuchun; Lu, Shihua

    2001-01-01

    ... (Russell et al,, 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat flux Q to air / sea temperature difference DeltaT by a relaxation coefficient K...

  6. Development of a Convective Heat Transfer Correlation of a Supercritical CO{sub 2} with Vertical Downward Flow in Circular Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Tae Ho; Kim, Hwan Yeol; Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    Pressure of coolant flowing through a SCWR core subchannel is supercritical and the heat transfer behavior is known to be quite different from those at a subcritical pressure. Therefore the heat transfer study in a supercritical pressure is required for the acquisition of a reliable heat transfer correlation. A downward flow as well as an upward flow occurs in a multi-pass reactor core. The heat transfer at a supercritical pressure in downward channel has been known to result in a quite different behavior from an upward flow. An experiment for a supercritical CO{sub 2} flowing vertically downward in circular tubes with inner diameters of 6.32 mm and 9 mm was performed by using SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation) at KAERI. The obtained test results are compared with the estimations from the existing correlations and an empirical formula for a downward flow is suggested.

  7. Properties of the histogram location approach and the extent and change of downward nominal wage rigidity in the EU

    Directory of Open Access Journals (Sweden)

    Andreas Behr

    2006-06-01

    Full Text Available The histogram location approach has been proposed by Kahn (1997 to estimate the fraction of wage cuts prevented by downward nominal wage rigidity. In this paper, we analyze the validity of the approach by means of a simulation study which yielded evidence of unbiasedness but also of potential underestimation of rigidity parameter uncertainty and therefore of potential anticonservative inference. We apply the histogram location approach to estimate the extent of downward nominal wage rigidity across the EU for 1995-2001. Our data base is the User Data Base (UDB of the European Community Household Panel (ECHP. The results show wide variation in the fraction of wage cuts prevented by nominal wage rigidity across the EU. The lowest rigidity parameters are found for the UK, Spain and Ireland, the largest for Portugal and Italy. Analyzing the change of rigidity between sub periods 1995-1997 and 1999-2001 even shows an widening of the differences in nominal wage rigidity. Due to the finding of large differences across the EU, the results imply that the costs of low inflation policies across the EU differ substantially.

  8. Downward Migration of Coastal Conifers as a Response to Recent Land Emergence in Eastern Hudson Bay, Québec

    Science.gov (United States)

    Bégin, Yves; Bérubé, Dominique; Grégoire, Martin

    1993-07-01

    Postglacial uplift in the eastern Hudson Bay area is among the most rapid in the world (300 m during the last 8000 yr). Although emergence curves based on 14 C-dated raised shorelines give a consistent basis for modeling relative sea-level changes, such a low-resolution dating method is inappropriate for estimating trends over recent decades. A major downward displacement of white spruce ( Picea glauca (Moench) Voss) and tamarack ( Larix laricina (DuRoi) K. Koch) occurred on protected shores as a response to shoreline retreat during this century. Analysis of the age distribution of trees indicates a progradation of white spruce and tamarack on gently sloping terrain ranging from 1.3 and 2.6 cm/yr, respectively, toward the sea. Improvement of climatic conditions during the 20th century favored such expansion which was probably faster than the real land emergence rates, but recent episodes of high water levels caused regression of forest margins over the highly exposed shores. Nevertheless, the downward trend of the treeline over this century substantiates the projections of 14C-dated coastal emergence curves during the modern period (1.0 to 1.3 cm/yr) by providing an estimate of the maximum rates of shoreline retreat.

  9. Shutterless non-uniformity correction for the long-term stability of an uncooled long-wave infrared camera

    Science.gov (United States)

    Liu, Chengwei; Sui, Xiubao; Gu, Guohua; Chen, Qian

    2018-02-01

    For the uncooled long-wave infrared (LWIR) camera, the infrared (IR) irradiation the focal plane array (FPA) receives is a crucial factor that affects the image quality. Ambient temperature fluctuation as well as system power consumption can result in changes of FPA temperature and radiation characteristics inside the IR camera; these will further degrade the imaging performance. In this paper, we present a novel shutterless non-uniformity correction method to compensate for non-uniformity derived from the variation of ambient temperature. Our method combines a calibration-based method and the properties of a scene-based method to obtain correction parameters at different ambient temperature conditions, so that the IR camera performance can be less influenced by ambient temperature fluctuation or system power consumption. The calibration process is carried out in a temperature chamber with slowly changing ambient temperature and a black body as uniform radiation source. Enough uniform images are captured and the gain coefficients are calculated during this period. Then in practical application, the offset parameters are calculated via the least squares method based on the gain coefficients, the captured uniform images and the actual scene. Thus we can get a corrected output through the gain coefficients and offset parameters. The performance of our proposed method is evaluated on realistic IR images and compared with two existing methods. The images we used in experiments are obtained by a 384× 288 pixels uncooled LWIR camera. Results show that our proposed method can adaptively update correction parameters as the actual target scene changes and is more stable to temperature fluctuation than the other two methods.

  10. Solar radiation, cloudiness and longwave radiation over low-latitude glaciers: implications for mass-balance modelling

    Science.gov (United States)

    Mölg, Thomas; Cullen, Nicolas J.; Kaser, Georg

    Broadband radiation schemes (parameterizations) are commonly used tools in glacier mass-balance modelling, but their performance at high altitude in the tropics has not been evaluated in detail. Here we take advantage of a high-quality 2 year record of global radiation (G) and incoming longwave radiation (L↓) measured on Kersten Glacier, Kilimanjaro, East Africa, at 5873 m a.s.l., to optimize parameterizations of G and L↓. We show that the two radiation terms can be related by an effective cloud-cover fraction neff, so G or L↓ can be modelled based on neff derived from measured L↓ or G, respectively. At neff = 1, G is reduced to 35% of clear-sky G, and L↓ increases by 45-65% (depending on altitude) relative to clear-sky L↓. Validation for a 1 year dataset of G and L↓ obtained at 4850 m on Glaciar Artesonraju, Peruvian Andes, yields a satisfactory performance of the radiation scheme. Whether this performance is acceptable for mass-balance studies of tropical glaciers is explored by applying the data from Glaciar Artesonraju to a physically based mass-balance model, which requires, among others, G and L↓ as forcing variables. Uncertainties in modelled mass balance introduced by the radiation parameterizations do not exceed those that can be caused by errors in the radiation measurements. Hence, this paper provides a tool for inclusion in spatially distributed mass-balance modelling of tropical glaciers and/or extension of radiation data when only G or L↓ is measured.

  11. Temperature properties in the tropical tropopause layer and their correlations with Outgoing Longwave Radiation: FORMOSAT-3/COSMIC observations

    Science.gov (United States)

    Wang, Kaiti; Wu, Yi-chao; Lin, Jia-Ting; Tan, Pei-Hua

    2018-06-01

    The properties of temperature at the level of lapse rate minimum (LRM) in the tropical tropopause layer between 20°S and 20°N are investigated using 3-year radio occultation observations based on the FORMOSAT-3/COSMIC mission from November of 2006 to October of 2009. The correlations between this LRM temperature and Outgoing Longwave Radiation (OLR) are analyzed by 5° × 5° grids in longitude and latitude. Two primary regions, one from 60°E to 180°E and the other from 90°W to 30°E, are found to have higher correlations and can be associated with regions of lower OLR values. The patterns of this spatial distributions of regions with higher correlations begin to change more obviously when the altitude ascends to the level of Cold Point Tropopause (CPT). This correlation at the LRM altitude in annual and seasonal scales also shows spatial distributions associated with OLR intensities. The altitudinal dependence of the correlations between temperature and OLR is further analyzed based on grids of high correlations with significance at LRM altitude, for the two primary regions. The results show that for the different time scales in this analysis (3-year, annual, and seasonal), the correlations all gradually decrease above the LRM levels but maintain a significant level to as high as 2.5-3.5 km. Below the LRM level, the correlation decreases with a slower rate as the altitude descends and still keeps significant at the deep 5 km level. These suggest that the vertical temperature profiles could be affected by the convection mechanism for a wide range of altitudes in the troposphere even above LRM altitude. Applying the same analysis on one complete La Niña event during the survey period also reveals similar features.

  12. Classification of tree species based on longwave hyperspectral data from leaves, a case study for a tropical dry forest

    Science.gov (United States)

    Harrison, D.; Rivard, B.; Sánchez-Azofeifa, A.

    2018-04-01

    Remote sensing of the environment has utilized the visible, near and short-wave infrared (IR) regions of the electromagnetic (EM) spectrum to characterize vegetation health, vigor and distribution. However, relatively little research has focused on the use of the longwave infrared (LWIR, 8.0-12.5 μm) region for studies of vegetation. In this study LWIR leaf reflectance spectra were collected in the wet seasons (May through December) of 2013 and 2014 from twenty-six tree species located in a high species diversity environment, a tropical dry forest in Costa Rica. A continuous wavelet transformation (CWT) was applied to all spectra to minimize noise and broad amplitude variations attributable to non-compositional effects. Species discrimination was then explored with Random Forest classification and accuracy improved was observed with preprocessing of reflectance spectra with continuous wavelet transformation. Species were found to share common spectral features that formed the basis for five spectral types that were corroborated with linear discriminate analysis. The source of most of the observed spectral features is attributed to cell wall or cuticle compounds (cellulose, cutin, matrix glycan, silica and oleanolic acid). Spectral types could be advantageous for the analysis of airborne hyperspectral data because cavity effects will lower the spectral contrast thus increasing the reliance of classification efforts on dominant spectral features. Spectral types specifically derived from leaf level data are expected to support the labeling of spectral classes derived from imagery. The results of this study and that of Ribeiro Da Luz (2006), Ribeiro Da Luz and Crowley (2007, 2010), Ullah et al. (2012) and Rock et al. (2016) have now illustrated success in tree species discrimination across a range of ecosystems using leaf-level spectral observations. With advances in LWIR sensors and concurrent improvements in their signal to noise, applications to large-scale species

  13. An experimental study on the negative effects of downwards flow of the melted frost over a multi-circuit outdoor coil in an air source heat pump during reverse cycle defrosting

    International Nuclear Information System (INIS)

    Song, Mengjie; Pan, Dongmei; Li, Ning; Deng, Shiming

    2015-01-01

    Highlights: • A special experimental rig was built and its details are reported. • The negative effects of downwards flowing of the melted frost were shown. • Defrosting duration was shortened after installing water collecting trays. • Temperature of melted frost decreased after installing trays. - Abstract: When the surface temperature of the outdoor coil in an air source heat pump (ASHP) unit is lower than both freezing point of water and the air dew point, frost can be formed and accumulated over outdoor coil surface. Frosting affects the energy efficiency, and periodic defrosting therefore is necessary. Reverse cycle defrosting is currently the most widely used defrosting method. A previous related study has indicated that during reverse cycle defrosting, downwards flow of the melted frost over a multi-circuit outdoor coil could affect the defrosting performance, without however giving detailed quantitative analysis of the effects. Therefore an experimental study on the effects has been carried out and a quantitative analysis conducted using the experimental data. In this paper, the detailed description of an experimental ASHP unit which was specifically built up is firstly reported. This is followed by presenting experimental results. Result analysis and conclusions are finally given

  14. Experimental Study on Downwardly Spreading Flame over Inclined Polyethylene-insulated Electrical Wire with Applied AC Electric Fields

    KAUST Repository

    Lim, Seung Jae

    2014-12-30

    An experimental study on downwardly spreading flame over slanted electrical wire, which is insulated by Polyethylene (PE), was conducted with applied AC electric fields. The result showed that the flame spread rate decreased initially with increase in inclination angle of wire and then became nearly constant. The flame shape was modified significantly with applied AC electric field due to the effect of ionic wind. Such a variation in flame spread rate could be explained by a thermal balance mechanism, depending on flame shape and slanted direction of flame. Extinction of the spreading flame was not related to angle of inclination, and was described well by a functional dependency upon the frequency and voltage at extinction.

  15. Collector Efficiency in Downward-Type Double-Pass Solar Air Heaters with Attached Fins and Operated by External Recycle

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2012-07-01

    Full Text Available The collector efficiency in a downward-type double-pass external-recycle solar air heater with fins attached on the absorbing plate has been investigated theoretically. Considerable improvement in collector efficiency is obtainable if the collector is equipped with fins and the operation is carried out with an external recycle. Due to the recycling, the desirable effect of increasing the heat transfer coefficient compensates for the undesirable effect of decreasing the driving force (temperature difference of heat transfer, while the attached fins provide an enlarged heat transfer area. The order of performances in the devices of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

  16. Uncertainty in RELAP5/MOD3.2 calculations for interfacial drag in downward two-phase flow

    International Nuclear Information System (INIS)

    Clark, Collin; Schlegel, Joshua P.; Hibiki, Takashi; Ishii, Mamoru; Kinoshita, Ikuo

    2016-01-01

    Highlights: • Uncertainty propagation is key for best estimate code reliability. • Uncertainty in drift flux correlations used to evaluate uncertainty in interfacial drag. • Bias and error have been compared for various models. - Abstract: RELAP5/MOD3.2 is a thermal-hydraulic system analysis code used to predict the response of nuclear reactor coolant systems in the event of certain accident scenarios. It is important that RELAP and other system analysis codes are able to accurately predict various two-phase flow phenomena, particularly the interfacial transfers between the liquid and gas phases. It is also important to understand how much uncertainty exists in these predictions due to uncertainties in the constitutive relations used to close the two-fluid model. In this paper, the uncertainty in the interfacial drag calculated by RELAP5/MOD3.2 due to errors in the drift-flux models used to close the model is evaluated and compared to the correlation developed by Goda et al. (2003). The case of downward flow is considered due to the importance of co-current and counter-current downward flow for predicting behavior in the downcomer of reactor systems during small-break Loss of Coolant Accidents (LOCAs) in nuclear reactor systems. The overall uncertainty in the interfacial force calculations due to error in the distribution parameter models were found to have a bias of +8.1% and error of 20.1% for the models used in RELAP5, and a bias of −30.8% and error of 23.1% for the correlation of Goda et al. (2003). However this analysis neglects the effects of compensating errors in the drift-flux parameters, as the drift velocity is assumed to be perfectly accurate. More physically meaningful results could be obtained if the distribution parameter and drift velocity were calculated directly from local phase concentration and velocity measurements, however no studies were available which included all of this information.

  17. Identification of retinal ganglion cells and their projections involved in central transmission of information about upward and downward image motion.

    Directory of Open Access Journals (Sweden)

    Keisuke Yonehara

    Full Text Available The direction of image motion is coded by direction-selective (DS ganglion cells in the retina. Particularly, the ON DS ganglion cells project their axons specifically to terminal nuclei of the accessory optic system (AOS responsible for optokinetic reflex (OKR. We recently generated a knock-in mouse in which SPIG1 (SPARC-related protein containing immunoglobulin domains 1-expressing cells are visualized with GFP, and found that retinal ganglion cells projecting to the medial terminal nucleus (MTN, the principal nucleus of the AOS, are comprised of SPIG1+ and SPIG1(- ganglion cells distributed in distinct mosaic patterns in the retina. Here we examined light responses of these two subtypes of MTN-projecting cells by targeted electrophysiological recordings. SPIG1+ and SPIG1(- ganglion cells respond preferentially to upward motion and downward motion, respectively, in the visual field. The direction selectivity of SPIG1+ ganglion cells develops normally in dark-reared mice. The MTN neurons are activated by optokinetic stimuli only of the vertical motion as shown by Fos expression analysis. Combination of genetic labeling and conventional retrograde labeling revealed that axons of SPIG1+ and SPIG1(- ganglion cells project to the MTN via different pathways. The axon terminals of the two subtypes are organized into discrete clusters in the MTN. These results suggest that information about upward and downward image motion transmitted by distinct ON DS cells is separately processed in the MTN, if not independently. Our findings provide insights into the neural mechanisms of OKR, how information about the direction of image motion is deciphered by the AOS.

  18. Analysis of the Electronic Crosstalk Effect in Terra MODIS Long-Wave Infrared Photovoltaic Bands Using Lunar Images

    Science.gov (United States)

    Wilson, Truman; Wu, Aisheng; Wang, Zhipeng; Xiong, Xiaoxiong

    2016-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the key sensors among the suite of remote sensing instruments on board the Earth Observing System Terra and Aqua spacecrafts. For each MODIS spectral band, the sensor degradation has been measured using a set of on-board calibrators. MODIS also uses lunar observations from nearly monthly spacecraft maneuvers, which bring the Moon into view through the space-view port, helping to characterize the scan mirror degradation at a different angles of incidence. Throughout the Terra mission, contamination of the long-wave infrared photovoltaic band (LWIR PV, bands 27-30) signals has been observed in the form of electronic crosstalk, where signal from each of the detectors among the LWIR PV bands can leak to the other detectors, producing a false signal contribution. This contamination has had a noticeable effect on the MODIS science products since 2010 for band 27, and since 2012 for bands 28 and 29. Images of the Moon have been used effectively for determining the contaminating bands, and have also been used to derive correction coefficients for the crosstalk contamination. In this paper, we introduce an updated technique for characterizing the crosstalk contamination among the LWIR PV bands using data from lunar calibration events. This approach takes into account both the in-band and out-of-band contribution to the signal contamination for each detector in bands 27-30, which is not considered in previous works. The crosstalk coefficients can be derived for each lunar calibration event, providing the time dependence of the crosstalk contamination. Application of these coefficients to Earth-view image data results in a significant reduction in image contamination and a correction of the scene radiance for bands 27- 30. Also, this correction shows a significant improvement to certain threshold tests in the MODIS Level-2 Cloud Mask. In this paper, we will detail the methodology used to identify and correct

  19. Flow regime visualization and pressure drops of HFO-1234yf, R-134a and R-410A during downward two-phase flow in vertical return bends

    International Nuclear Information System (INIS)

    Padilla, Miguel; Revellin, Rémi; Wallet, Jérémy; Bonjour, Jocelyn

    2013-01-01

    Highlights: ► Visual observation of two-phase flow regimes during downward flow in a return bend. ► Bubble and vapor slug dynamical behaviors in downward slug flow are reported. ► Perturbation lengths up- and downstream of the return bend have been investigated. ► Measurement of 285 pressure drop data points for HFO-1234yf, R-134a and R-410A. -- Abstract: This paper provides a qualitative visual observation of the two-phase flow patterns for HFO-1234yf and R-134a during downward flow in a vertical 6.7 mm inner diameter glass return bend. The different flow regimes observed are: slug, intermittent and annular flows. Bubble and vapor slug dynamical behaviors in downward slug flow are reported for HFO-1234yf. In addition, to determine the perturbation lengths up- and downstream of the return bend, the total pressure drop has been measured at different pressure tap location up- and downstream of the singularity. Furthermore, 285 pressure drop data points measured for two-phase flow of HFO-1234yf, R-134a and R-410A in vertical downward flow return bends are presented. The flow behavior in the return bend, which is subjected to the complex combined actions of gravity and centrifugal force was expressed in terms of the vapor Froude number. This experimental pressure drop database, which is included in the appendix, is compared to four well-known prediction methods available in the literature

  20. An experimental study on two-phase pressure drop in small diameter horizontal, downward inclined and vertical tubes

    Directory of Open Access Journals (Sweden)

    Autee Arun

    2015-01-01

    Full Text Available An experimental study of two-phase pressure drop in small diameter tubes orientated horizontally, vertically and at two other downward inclinations of θ= 300 and θ = 600 is described in this paper. Acrylic transparent tubes of internal diameters 4.0, 6.0, and 8.0 mm with lengths of 400 mm were used as the test section. Air-water mixture was used as the working fluid. Two-phase pressure drop was measured and compared with the existing correlations. These correlations are commonly used for calculation of pressure drop in macro and mini-microchannels. It is observed that the existing correlations are inadequate in predicting the two-phase pressure drop in small diameter tubes. Based on the experimental data, a new correlation has been proposed for predicting the two-phase pressure drop. This correlation is developed by modification of Chisholm parameter C by incorporating different parameters. It was found that the proposed correlation predicted two-phase pressure drop at satisfactory level.

  1. Seasonal contrast in the surface energy balance of the Sahel

    Science.gov (United States)

    Miller, R. L.; Slingo, A.; Barnard, J. C.; Kassianov, E.

    2009-07-01

    Over much of the world, heating of the surface by sunlight is balanced predominately by evaporative cooling. However, at the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) in Niamey, Niger, evaporation makes a significant contribution to the surface energy balance only at the height of the rainy season, when precipitation has replenished the reservoir of soil moisture. The AMF was placed at Niamey from late 2005 to early 2007 to provide measurements of surface fluxes in coordination with geostationary satellite retrievals of radiative fluxes at the top of the atmosphere, as part of the RADAGAST experiment to calculate atmospheric radiative divergence. We use observations at the mobile facility to investigate how the surface adjusts to radiative forcing throughout the year. The surface response to solar heating varies with changes in atmospheric water vapor associated with the seasonal reversal of the West African monsoon, which modulates the greenhouse effect and the ability of the surface to radiate thermal energy directly to space. During the dry season, sunlight is balanced mainly by longwave radiation and the turbulent flux of sensible heat. The ability of longwave radiation to cool the surface drops after the onset of southwesterly surface winds at Niamey, when moist, oceanic air flows onshore, increasing local column moisture and atmospheric opacity. Following the onset of southwesterly flow, evaporation remains limited by the supply of moisture from precipitation. By the height of the rainy season, however, sufficient precipitation has accumulated that evaporation is controlled by incident sunlight, and radiative forcing of the surface is balanced comparably by the latent, sensible, and longwave fluxes. Evaporation increases with the leaf area index, suggesting that plants are a significant source of atmospheric moisture and may tap moisture stored beneath the surface that accumulated during a previous rainy season. Surface radiative forcing

  2. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.; Wilson, S. K.; Duffy, B. R.

    2014-01-01

    large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a

  3. The Remote Sensing of Surface Radiative Temperature over Barbados.

    Science.gov (United States)

    remote sensing of surface radiative temperature over Barbados was undertaken using a PRT-5 attached to a light aircraft. Traverses across the centre of the island, over the rugged east coast area, and the urban area of Bridgetown were undertaken at different times of day and night in the last week of June and the first week of December, 1969. These traverses show that surface variations in long-wave radiation emission lie within plus or minus 5% of the observations over grass at a representative site. The quick response of the surface to sunset and sunrise was

  4. Surface radiation changes and their impact on climate in Central Europe[Dissertation 17578

    Energy Technology Data Exchange (ETDEWEB)

    Ruckstuhl, Ch.

    2008-07-01

    forcing on surface temperature, direct aerosol forcing is found to be about five times larger than the forcing due to changing clouds. First order estimates using mean climate sensitivity factors indicate that with the observed strong aerosol decline the direct and the indirect aerosol and cloud forcing combined may have produced about one third of the recent rapid temperature increase observed in Central Europe since the 1980s. The observed relation of decreasing AOD and consequently increasing solar radiation under cloud-free skies has been confirmed by MODTRAN (MODerate spectral resolution atmospheric TRANsmittance algorithm and computer model) calculations. MODTRAN calculations further indicate that the observed increase in water vapor has at least a five times smaller impact on solar irradiance transmission under cloud-free skies than the measured aerosol optical depth decline has. For the conducted analysis of solar radiation under cloud-free skies, a new method has been developed to automatically detect cloud-free skies. The method is based on sunshine duration measurements and the variability of the atmospheric transmission derived from global solar irradiance measurements. This new method presents the advantage to use standard solar radiation parameters that are usually measured at advanced meteorological stations. To validate state-of-the-art radiometers a one year radiometer comparison campaign has been performed at the Payerne Baseline Surface Radiation Network (BSRN) site. The comparison has shown that state-of-the-art Kipp and Zonen pyranometers measure global solar irradiance within 1.6%, and if a field adjustment is performed the uncertainty even reduces to 1.0% on monthly means. If Eppley PSP pyranometers are also considered, the uncertainties are about twice as large. In order to explore the total surface radiation budget, a parameterization has been derived to estimate longwave downward radiation (LDR) from surface humidity and column integrated water

  5. Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora

    Directory of Open Access Journals (Sweden)

    H. Gunell

    2015-10-01

    Full Text Available The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electron phase-space holes through beam–plasma interaction. The double layer is disrupted when reaching altitudes of 1–2 Earth radii where the Langmuir condition no longer can be satisfied due to the diminishing density of electrons coming up from the ionosphere. During the disruption the potential drop is in part carried by the electron holes. The disruption creates favourable conditions for double layer formation near the ionosphere and double layers form anew in that region. The process repeats itself with a period of approximately 1 min. This period is determined by how far the double layer can reach before being disrupted: a higher disruption altitude corresponds to a longer repetition period. The disruption altitude is, in turn, found to increase with ionospheric density and to decrease with total voltage. The current displays oscillations around a mean value. The period of the oscillations is the same as the recurrence period of the double layer formations. The oscillation amplitude increases with increasing voltage, whereas the mean value of the current is independent of voltage in the 100 to 800 V range covered by our simulations. Instead, the mean value of the current is determined by the electron density at the ionospheric boundary.

  6. Modeling the downward transport of 210Pb in Peatlands: Initial Penetration‐Constant Rate of Supply (IP-CRS) model

    International Nuclear Information System (INIS)

    Olid, Carolina; Diego, David; Garcia-Orellana, Jordi; Cortizas, Antonio Martínez; Klaminder, Jonatan

    2016-01-01

    The vertical distribution of 210 Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210 Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210 Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210 Pb ( 210 Pb xs ) in peat taking into account both incorporation of 210 Pb into the accumulating peat matrix as well as an initial flushing of 210 Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210 Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used 210 Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241 Am and 137 Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210 Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene. - Highlights: • Accurate age dating of peat and sediment cores is critical for evaluating change. • A new 210 Pb dating model that includes vertical transport of 210 Pb was developed. • The IP-CRS model provided consistent peat accumulation rates. • The IP-CRS ages were consistent with independent chronological markers. • The IP-CRS model derives peat ages where downward 210 Pb transport is evidenced.

  7. Exhaustive Classification of the Invariant Solutions for a Specific Nonlinear Model Describing Near Planar and Marginally Long-Wave Unstable Interfaces for Phase Transition

    Science.gov (United States)

    Ahangari, Fatemeh

    2018-05-01

    Problems of thermodynamic phase transition originate inherently in solidification, combustion and various other significant fields. If the transition region among two locally stable phases is adequately narrow, the dynamics can be modeled by an interface motion. This paper is devoted to exhaustive analysis of the invariant solutions for a modified Kuramoto-Sivashinsky equation in two spatial and one temporal dimensions is presented. This nonlinear partial differential equation asymptotically characterizes near planar interfaces, which are marginally long-wave unstable. For this purpose, by applying the classical symmetry method for this model the classical symmetry operators are attained. Moreover, the structure of the Lie algebra of symmetries is discussed and the optimal system of subalgebras, which yields the preliminary classification of group invariant solutions is constructed. Mainly, the Lie invariants corresponding to the infinitesimal symmetry generators as well as associated similarity reduced equations are also pointed out. Furthermore, the nonclassical symmetries of this nonlinear PDE are also comprehensively investigated.

  8. Radiation observation at Dome Fuji Station, Antarctica

    Directory of Open Access Journals (Sweden)

    Naohiko Hirasawa

    2008-06-01

    Full Text Available This paper reports radiation observations at Dome Fuji Station from February 1, 2003 to January 20, 2004, carried out by the 44th Japanese Antarctic Research Expedition team. The radiometers which measured the upward longwave radiation (LWu, the downward longwave (LWd and the downward shortwave (SWd were equipped with fans to avoid frosting on the surface of the radiometer dome by air circulation. The upward shortwave radiation (SWu measured by a radiometer without fan needs correction, which we leave as a problem for the future. In addition, as for LWd and LWu in the polar night, a typical radiational cooling case and a suppressed radiational cooling one are shown.

  9. Time and spatial heat transfer performance around an isothermally heated sphere placed in a uniform, downwardly directed flow (in relation to the enhancement of latent heat storage rate in a spherical capsule)

    International Nuclear Information System (INIS)

    Koizumi, H.

    2004-01-01

    The aim of this study is to reveal the temporal and spatial heat transfer performance of an isothermally heated sphere placed in a uniform, downwardly directed flow using a micro-foil heat flow sensor (HFS). A HFS, whose response time is about 0.02 s, was pasted on the surface of a heated copper sphere. Experiments were carried out using air with a Grashof number of 3.3 x 10 5 and with several Reynolds numbers (Re) up to 1800. Three flow patterns appeared: a chaotic flow at Re<240; a two-dimensional steady separated flow at 240 ≤ Re<500, and a three-dimensional unsteady separated flow at Re ≥ 500. In addition, the instantaneous and time-averaged heat transfer performance around the sphere in each of the three regions was clarified. Next, enhancement of the latent heat storage rate of a solid phase change material (PCM) in a spherical capsule was performed. The flow around the spherical capsule, in which the solid PCM was filled and placed in a heated, upwardly directed flow, is the approximate adverse flow phenomenon around the heated sphere which was placed in a downwardly directed flow. In other words, the buoyant flow and the forced flow are in the opposite directions in these two cases. Tests of latent heat storage were run for two Reynolds numbers which represented different flow characteristics in the heat transfer experiments, Re=150 and 1800. Furthermore, copper plates were inserted into the solid PCM, of which thermal conductivity was considerably low, to enhance the latent heat storage rate for the two Reynolds number flows

  10. Scenarios for exposure of aquatic organisms to plant protection products in the Netherlands : part 1: Field crops and downward spraying

    NARCIS (Netherlands)

    Tiktak, A.; Adriaanse, P.I.; Boesten, J.J.T.I.; Griethuysen, van C.; Horst, ter M.M.S.; Linders, J.B.H.J.; Linden, van der A.M.A.; Zande, van de J.C.

    2012-01-01

    In the current Dutch authorisation procedure for calculating the exposure of surface water organisms to plant protection products, drift deposition is considered to be the only source for exposure of surface water organisms. Although drift can still be considered the most important source,

  11. A theoretical model of air and steam co-injection to prevent the downward migration of DNAPLs during steam-enhanced extraction

    Science.gov (United States)

    Kaslusky, Scott F.; Udell, Kent S.

    2002-04-01

    When steam is injected into soil containing a dense volatile non-aqueous phase liquid contaminant the DNAPL vaporized within the heated soil region condenses and accumulates ahead of the steam condensation front. If enough DNAPL accumulates, gravitational forces can overcome trapping forces allowing the liquid contaminant to flow downward. By injecting air with steam, a portion of the DNAPL vapor remains suspended in equilibrium with the air, decreasing liquid contaminant accumulation ahead of the steam condensation front, and thus reducing the possibility of downward migration. In this work, a one-dimensional theoretical model is developed to predict the injection ratio of air to steam that will prevent the accumulation of volatile DNAPLs. The contaminated region is modeled as a one-dimensional homogeneous porous medium with an initially uniform distribution of a single component contaminant. Mass and energy balances are combined to determine the injection ratio of air to steam that eliminates accumulation of the contaminant ahead of the steam condensation front, and hence reduces the possibility of downward migration. The minimum injection ratio that eliminates accumulation is defined as the optimum injection ratio. Example calculations are presented for three DNAPLs, carbon tetrachloride (CCl 4), trichloroethylene (TCE), and perchloroethylene (PCE). The optimum injection ratio of air to steam is shown to depend on the initial saturation and the volatility of the liquid contaminant. Numerical simulation results are presented to validate the model, and to illustrate downward migration for ratios less than optimum. Optimum injection ratios determined from numerical simulations are shown to be in good agreement with the theoretical model.

  12. The Downward Continuation to the Earth’s Surface of Truncated Spherical and Ellipsoidal Harmonic Series of the Gravity and Height Anomalies,

    Science.gov (United States)

    1981-12-01

    triangle OBQ, we obtain r c =COtI ose + sine (411) Hence with (4.10) e 2 sinecose (412)tan ip = (__o__2)_ 1 - e 2sin2 0 Pythagoras ’ theorem then easily...coordinate system. Strictly, this theorem tinds no application in our physical world since it guarantees convergence only outside the sphere enclosing...Junq, 1956, p.54 3 ; Moritz, 1980, p.52) is found, using the above theorem , to be f =E, the focal distance of the ellipsoid, shoving also that the

  13. Observations of the boiling process from a downward-facing torispherical surface: Confirmatory testing of the heavy water new production reactor flooded cavity design

    International Nuclear Information System (INIS)

    Chu, T.Y.; Bentz, J.H.; Simpson, R.B.

    1995-01-01

    Reactor-scale ex-vessel boiling experiments were performed in the CYBL facility at Sandia National Laboratories. The boiling flow pattern outside the RPV bottom head shows a center pulsating region and an outer steady two-phase boundary layer region. The local heat transfer data can be correlated in terms of a modified Rohsenow correlation

  14. Land-Surface-Atmosphere Coupling in Observations and Models

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2009-07-01

    Full Text Available The diurnal cycle and the daily mean at the land-surface result from the coupling of many physical processes. The framework of this review is largely conceptual; looking for relationships and information in the coupling of processes in models and observations. Starting from the surface energy balance, the role of the surface and cloud albedos in the shortwave and longwave fluxes is discussed. A long-wave radiative scaling of the diurnal temperature range and the night-time boundary layer is summarized. Several aspects of the local surface energy partition are presented: the role of soilwater availability and clouds; vector methods for understanding mixed layer evolution, and the coupling between surface and boundary layer that determines the lifting condensation level. Moving to larger scales, evaporation-precipitation feedback in models is discussed; and the coupling of column water vapor, clouds and precipitation to vertical motion and moisture convergence over the Amazon. The final topic is a comparison of the ratio of surface shortwave cloud forcing to the diabatic precipitation forcing of the atmosphere in ERA-40 with observations.

  15. Alteration of lymphocyte functions by 8-methoxypsoralen and longwave ultraviolet radiation. I. Suppressive effects of PUVA on T-lymphocyte migration in vitro

    International Nuclear Information System (INIS)

    Okamoto, H.; Takigawa, M.; Horio, T.

    1985-01-01

    We investigated the influence of 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet radiation (PUVA) on lymphocyte migration in vitro. Nylon wool-purified, mouse splenic T lymphocytes showed locomotive responses to casein, normal mouse serum (NMS), and zymosan-activated mouse serum (ZAS). Migratory responses to casein and NMS, and to ZAS were remarkably suppressed in lymphocytes exposed to 0.5 J/cm2 UVA plus 0.1 micrograms/ml 8-MOP and to 0.8 J/cm2 UVA plus 8-MOP, respectively. The PUVA treatment used in the present study had no effect on random movement and lymphocyte viability. T lymphocytes cultured in the absence of mitogenic agent for 24 h demonstrated a greater increase in their migration activity than noncultured cells, while lymphocytes cultured after 1.0 J/cm2 PUVA pretreatment remained low. These findings suggest that the therapeutic effect of PUVA on inflammatory skin disorders may be due in part to the suppression of lymphocyte migration

  16. Long-Wave Infrared (LWIR) Molecular Laser-Induced Breakdown Spectroscopy (LIBS) Emissions of Thin Solid Explosive Powder Films Deposited on Aluminum Substrates.

    Science.gov (United States)

    Yang, Clayton S-C; Jin, Feng; Trivedi, Sudhir B; Brown, Ei E; Hommerich, Uwe; Tripathi, Ashish; Samuels, Alan C

    2017-04-01

    Thin solid films made of high nitro (NO 2 )/nitrate (NO 3 ) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region. A preliminary assessment of the detection limit for a thin film of RDX on aluminum appears to be much lower than 60 µg/cm 2 . This LWIR LIBS setup is capable of rapidly probing and charactering samples without the need for elaborate sample preparation and also offers the possibility of a simultaneous ultraviolet visible and LWIR LIBS measurement.

  17. Cell cycle analysis of cultured mammalian cells after exposure to 4,5',8-trimethylpsoralen and long-wave ultraviolet light

    International Nuclear Information System (INIS)

    Cohen, S.R.; Burkholder, D.E.; Varga, J.M.; Carter, D.M.; Bartholomew, J.C.

    1981-01-01

    Cell cycle analysis was used to study the the effect of 4,5'8-trimethylpsoralen (TMP) and long-wave ultraviolet light (UV-A) on cultured mammalian cells. DNA distribution patterns were measured for murine melanoma cells (a cloned line of Cloudman S91) and a strain of diploid human skin fibroblasts (CRL 1295) using both a microfluorimetry procedure and flow cytometry. The untreated cells and those receiving TMP along and UV-A alone had identical DNA content as assessed at several posttreatment intervals (0-72 hr). The majority of cells in control groups contained a G1 DNA content, whereas exposure to TMP (2 x 10(-7) M) plus UV-A (1 Joule/cm2) led to the accumulation of cells in the G2 phase. These observations were similar for each cell type and both analytical techniques were in excellent agreement. The finding that psoralen plus UV-A induces a phase-specific G2 blockade in cultured cells has important implications for understanding the mechanisms which account for enhanced pigmentation and suppression of cellular proliferation following exposure to these agents in vivo

  18. Comparative investigation of long-wave infrared generation based on ZnGeP{sub 2} and CdSe optical parametric oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Bao-Quan, Yao; Gang, Li; Guo-Li, Zhu; Pei-Bei, Meng; You-Lun, Ju; Wang Yue-Zhu, E-mail: yaobq08@hit.edu.cn [National Key Laboratory of Tunable Laser Technology Harbin Institute of Technology Harbin 150001 (China)

    2012-03-15

    Long-wave infrared (IR) generation based on type-II (o{yields}e+o) phase matching ZnGeP{sub 2} (ZGP) and CdSe optical parametric oscillators (OPOs) pumped by a 2.05 {mu}m Tm,Ho:GdVO{sub 4} laser is reported. The comparisons of the bire-fringent walk-off effect and the oscillation threshold between ZGP and CdSe OPOs are performed theoretically and experimentally. For the ZGP OPO, up to 419 mW output at 8.04 {mu}m is obtained at the 8 kHz pump pulse repetition frequency (PRF) with a slope efficiency of 7.6%. This ZGP OPO can be continuously tuned from 7.8 to 8.5 {mu}m. For the CdSe OPO, we demonstrate a 64 mW output at 8.9 {mu}m with a single crystal 28 mm in length. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. Presbycusis: a human temporal bone study of individuals with downward sloping audiometric patterns of hearing loss and review of the literature.

    Science.gov (United States)

    Nelson, Erik G; Hinojosa, Raul

    2006-09-01

    The purpose of this retrospective case review was to identify patterns of cochlear element degeneration in individuals with presbycusis exhibiting downward sloping audiometric patterns of hearing loss and to correlate these findings with those reported in the literature to clarify conflicting concepts regarding the association between hearing loss and morphologic abnormalities. Archival human temporal bones from individuals with presbycusis were selected on the basis of strict audiometric criteria for downward-sloping audiometric thresholds. Twenty-one temporal bones that met these criteria were identified and compared with 10 temporal bones from individuals with normal hearing. The stria vascularis volumes, spiral ganglion cell populations, inner hair cells, and outer hair cells were quantitatively evaluated. The relationship between the severity of hearing loss and the degeneration of cochlear elements was analyzed using univariate linear regression models. Outer hair cell loss and ganglion cell loss was observed in all individuals with presbycusis. Inner hair cell loss was observed in 18 of the 21 individuals with presbycusis and stria vascularis loss was observed in 10 of the 21 individuals with presbycusis. The extent of degeneration of all four of the cochlear elements evaluated was highly associated with the severity of hearing loss based on audiometric thresholds at 8,000 Hz and the pure-tone average at 500, 1,000, and 2,000 Hz. The extent of ganglion cell degeneration was associated with the slope of the audiogram. Individuals with downward-sloping audiometric patterns of presbycusis exhibit degeneration of the stria vascularis, spiral ganglion cells, inner hair cells, and outer hair cells that is associated with the severity of hearing loss. This association has not been previously reported in studies that did not use quantitative methodologies for evaluating the cochlear elements and strict audiometric criteria for selecting cases.

  20. An Experimental Study on the Convective Heat Transfer in Narrow Rectangular Channels for Downward Flow to Predict Onset of Nucleate Boiling

    International Nuclear Information System (INIS)

    Song, Junghyun; Jeong, Yong Hoon; Lee, Juhyung; Chang, Soon Heung

    2014-01-01

    Research reactor is the nuclear reactor serves neutron source for many research fields such as neutron scattering, non-destructive testing, radioisotope treatment and so on. Due to that characteristic of research reactor, as many people work around the research reactor, research reactor should be designed to have much more conservative margin for normal operation. Boiling heat transfer is the one of the most efficient type in heat transfer modes, however, research reactor needs to avoid onset of nucleate boiling (ONB) in normal operation as IAEA recommend for research reactors to have enough ONB margin to maintain the normal operation state in 'IAEA-TECDOC-233' (1980) for the same reason explained above. Jordan Research and Training Reactor (JRTR) operates under downward flow in narrow rectangular channel in fuel assembly. There isn't sufficient heat transfer data under downward flow condition and only few ONB prediction correlation as well. In the present work, not only a new ONB prediction model would be developed, but also comparison between heat transfer data with several heat transfer correlations could be shown. In addition, as Sudo and Omar S. proposed differently about the Nusselt number behaviors in upward and downward convective heat transfer, the study of convective heat transfer should be conducted continuously to determine it exactly. In this paper, single-phase heat transfer data is analyzed by several heat transfer correlations before developing ONB prediction correlation. In this study, an experiment on the single-phase heat transfer was conducted. As shown in Fig. 5, comparison between experimental data and existing correlations shows quite huge difference as about 40%. Additional experiments on single-phase heat transfer at low heat flux are necessary to clarify the tendency of Nusselt number among heat flux and to develop new correlation for single-phase heat transfer

  1. Research Note : Near-surface layer replacement for sparse data: Is interpolation needed?

    NARCIS (Netherlands)

    Sun, Yimin; Verschuur, D.J.; Luo, Yi

    2017-01-01

    Near-surface problem is a common challenge faced by land seismic data processing, where often, due to near-surface anomalies, events of interest are obscured. One method to handle this challenge is near-surface layer replacement, which is a wavefield reconstruction process based on downward

  2. Balance of longwave radiation employing the rate of solar radiation for Santa Maria, Rio Grande do Sul, Brazil1

    Directory of Open Access Journals (Sweden)

    Evandro Zanini Righi

    Full Text Available New coefficients were determined for the weighting term for cloudiness in the Brunt-Penman equation using the rate of solar radiation (RK in place of the rate of sunshine duration (n/N. The coefficients in the Brutsaert method proposed for daytime in southern Brazil were also tested and adjusted, and the method was selected which gave the more accurate daily results in relation to the original Brunt-Penman equation, for Santa Maria in the state of Rio Grande do Sul, Brazil (RS. Meteorological data covering 2,472 days obtained from the automatic and conventional weather stations in Santa Maria were used. The coefficients were adjusted by linear and nonlinear regression methods depending on the model, using 2/3 of the data. The adjusted equations were tested with the remaining 1/3 of the data. The Brunt-Penman equation modified by the term for cloudiness weighted both for solar radiation incident on the surface with no cloudiness (RK,R and for solar radiation incident at the top of the atmosphere (RK,K, were those that resulted in the best statistical indices relative to the original Brunt-Penman equation. In those equations the boundary conditions, 0.3 ≥ RK,R ≥ 1 or RK,K ≤ 0.22, were imposed. Although having similar statistical indices, a sensitivity analysis showed that the Brutsaert equation and other weightings for cloudiness resulted in larger deviations when compared to the original Brunt-Penman equation, in addition to having greater complexity for practical application.

  3. Measuring the greenhouse effect and radiative forcing through the atmosphere

    Science.gov (United States)

    Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

    2013-04-01

    In spite of a large body of existing measurements of incoming shortwave solar radiation and outgoing longwave terrestrial radiation at the Earth's surface and at the top of the atmosphere, there are few observations documenting how radiation profiles change through the atmosphere - information that is necessary to fully quantify the greenhouse effect of the Earth's atmosphere. Using weather balloons and specific radiometer equipped radiosondes, we continuously measured shortwave and longwave radiation fluxes from the surface of the Earth up to altitudes of 35 kilometers in the upper stratosphere. Comparing radiation profiles from night measurements with different amounts of water vapor, we show evidence of large greenhouse forcing. We show, that under cloud free conditions, water vapor increases with Clausius-Clapeyron ( 7% / K), and longwave downward radiation at the surface increases by 8 Watts per square meter per Kelvin. The longwave net radiation however, shows a positive increase (downward) of 2.4 Watts per square meter and Kelvin at the surface, which decreases with height and shows a similar but negative increase (upward) at the tropopause. Hence, increased tropospheric water vapor increases longwave net radiation towards the ground and towards space, and produces a heating of 0.42 Kelvin per Watt per square meter at the surface. References: Philipona et al., 2012: Solar and thermal radiation profiles and radiative forcing measured through the atmosphere. Geophys. Res. Lett., 39, L13806, doi: 10.1029/2012GL052087.

  4. Experimental study on in-vessel debris coolability; experiments on heat transfer in downward-facing hemicircular gap

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Kune Yull; Kim, Yong Hoon; Kim, Seong Joong; Lee, Seung Dong [Seoul National University, Seoul (Korea)

    2002-03-01

    Experiments were performed to measure the CHF and the critical power and to investigate the heat transfer mechanism in the narrow gap with 2D slice test sections. Test parameters in this study included the gap size of 1, 2, 5, and 10mm and the system pressure from 0.1 to 1.0 MPa. The CHF was measured for the distilled water. Results of this study may be summarized as follows. 1) In the narrow gap size of 1 and 2mm, the CHF occurs at the bottom and propagates upwards as the inclination angle relative to gravitational force increases. 2) Dryout is the limiting heat transfer mechanism in the 2D sliced experiments, and the CHF reaches 80-90% of the 3D CHFG value. 3) In the narrow gap size of 1 and 2mm the CHF values lie on the order of 104 kW/m2, while in the gap sizes of 5 and 10mm the CHF values have an order of 105 kW/m2. 4) The flow visualization study revealed that the shape of bubble is elliptic and the hydrodynamic bubble diameter exceeds the size of 20mm. 5) In analyzing the CHF with the inclination angle of the heated surface in the narrow gap size of 1 and 2mm, there exists a transition angle in the vicinity of 20-30 .deg.. From the region of the inclination angle of 0 .deg. C to 20 .deg. C or 30 .deg. C, the dryout mechanism may be directly applicable. On the contrary the transition angle is not conspicuously seen in the gap sizes of 5 and 10mm in which dominant mechanism is closer to pool boiling. 27 refs., 29 figs., 8 tabs. (Author)

  5. Galileo Probe Doppler Residuals as the Wave-Dynamical Signature of Weakly Stable, Downward-Increasing Stratification in Jupiter's Deep Wind Layer

    Science.gov (United States)

    Allison, Michael; Atkinson, David H.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Doppler radio tracking of the Galileo probe-to-orbiter relay, previously analyzed for its in situ measure of Jupiter's zonal wind at the equatorial entry site, also shows a record of significant residual fluctuations apparently indicative of varying vertical motions. Regular oscillations over pressure depth in the residual Doppler measurements of roughly 1-8 Hz (increasing upward), as filtered over a 134 sec window, are most plausibly interpreted as gravity waves, and imply a weak, but downward increasing static stability within the 5 - 20 bar region of Jupiter's atmosphere. A matched extension to deeper levels of an independent inertial stability constraint from the measured vertical wind shear at 1 - 4 bars is roughly consistent with a static stability of approximately 0.5 K/km near the 20 bar level, as independently detected by the probe Atmospheric Structure Instrument.

  6. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    Science.gov (United States)

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, D.

    2015-10-01

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  7. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    International Nuclear Information System (INIS)

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Shiraki, D.; Eidietis, N. W.; Parks, P. B.; Lasnier, C. J.

    2015-01-01

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect

  8. Refining surface net radiation estimates in arid and semi-arid climates of Iran

    Science.gov (United States)

    Golkar, Foroogh; Rossow, William B.; Sabziparvar, Ali Akbar

    2018-06-01

    an alternative was checked and found to not improve the agreement. The MODIS surface albedos differed from the ISCCP FD values by no more than 0.02-0.07, but because these differences are mostly at longer wavelengths, they did not change the net solar radiation very much. Therefore to obtain the best estimate of surface net radiation with the best combination of spatial and temporal resolution, we developed a method to adjust the ISCCP FD surface longwave fluxes using the AIRS surface air and skin temperatures to obtain the higher spatial resolution of the latter (45 km), while retaining the 3-h time intervals of the former. Overall, the refinements reduced the ISCCP FD longwave flux magnitudes by about 25.5-42.1 W/m2 RMS (maximum difference -27.5 W/m2 for incoming longwave radiation and -59 W/m2 for outgoing longwave radiation) with the largest differences occurring at 9:00 and 12:00 UTC near local noon. Combining the ISCCP FD net shortwave radiation data and the AIRS-modified net longwave radiation data changed the total net radiation for summertime by 4.64 to 61.5 W/m2 and for wintertime by 1.06 to 41.88 W/m2 (about 11.1-39.2% of the daily mean).

  9. Oblique Longwave Infrared Atmospheric Compensation

    Science.gov (United States)

    2017-09-14

    been updated to take terrain shape from a digital elevation model into account, as well as multiple viewing geometries for the different pixels...utilizing a digital elevation map). In summary, OISAC simply estimates line contributions for the transmission and path radiance, τ̄` and L̄p,`, from the...and Atmospheric Administration (NOAA) National Operational Model Archive and Distribution System ( NOMADS ) [34]. At- mospheric estimates from the

  10. Investigation of the effect of sealed surfaces on local climate in urban areas

    Science.gov (United States)

    Weihs, Philipp; Hasel, Stefan; Mursch-Radlgruber, Erich; Gützer, Christian; Krispel, Stefan; Peyerl, Martin; Trimmel, Heidi

    2015-04-01

    Local climate is driven by the interaction between energy balance and energy transported by advected air. Short-wave and long-wave radiation are major components in this interaction. Some few studies (e.g. Santamouris et al.) showed that adjusting the grade of reflection of surfaces is an efficient way to influence temperature. The present study investigates the influence of high albedo concrete surfaces on local climate. The first step of the study consisted of experimental investigations: routine measurements of the short and longwave radiation balance, of the ground and of the air temperature and humidity at different heights above 6 different types of sealed surfaces were performed. During this measurement campaign the above mentioned components were measured over a duration of 4 months above two conventional asphalt surfaces, one conventional concrete and three newly developed concrete surfaces with increased reflectances. Measured albedo values amounted to 0.12±0.02 for the asphalt surfaces and to maximum values of 0.56 for high albedo concrete. The maximum difference in surface temperature between the asphalt surfaces and the high albedo concrete surfaces amounted to 15°C. In addition the emission constants of the different sealed surfaces were also determined and were compared to values from literature.. In a second step the urban energy balance model Envi_Met was used to simulate the surface temperature of the six surfaces. The simulated surface temperatures were compared to the measured surface temperatures and statements as to uncertainties of the model simulations were made In a third step, Envi_Met was used to simulate the local climate of an urban district in Vienna. The surface and air temperature and the SW, LW fluxes were calculated for different types of sealed surfaces. By performing calculations of thermal stress indices (UTCI, PMV), statements as to the influence of the type of sealed surface on thermal stress on humans was made.

  11. Microclimatic conditions at the external surface of building envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Kragh, M.K.

    1998-12-31

    The project is described, the motivation for the research and the microclimate is defined in relation to both building physics research and applications. Air temperatur, air humidity, solar radiation and air velocity are briefly considered, whilst driving rain and long-wave radiation are described in more detail. Convective heat transfer and surface coefficients are discussed, although they are not microclimatic factors, merely resulting from combinations of such factors. They are included as they are important in relation to transfer of heat and moisture at the surface of the building envelope. Driving rain measurement is the main area of interest, including development of measurement equipment. Long-wave irradiation is measured and compared with empirical formulae from the literature. Window convection heat transfer is another main area of interest. Nocturnal convective heat transfer from a double pane glazing is studied and measurement principles are discussed. Finally, a compilation of meteorological data for hygrothermal simulations, including estimation of driving rain, is described. System error estimation in relation to the window convection measurements, design notes on an apparatus for external convection measurement, formulae for conversion of relative humitity and dry-bulb temperature into dew point temperature. (EG) 66 refs.

  12. Microclimatic conditions at the external surface of building envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Kragh, M K

    1999-12-31

    The project is described, the motivation for the research and the microclimate is defined in relation to both building physics research and applications. Air temperatur, air humidity, solar radiation and air velocity are briefly considered, whilst driving rain and long-wave radiation are described in more detail. Convective heat transfer and surface coefficients are discussed, although they are not microclimatic factors, merely resulting from combinations of such factors. They are included as they are important in relation to transfer of heat and moisture at the surface of the building envelope. Driving rain measurement is the main area of interest, including development of measurement equipment. Long-wave irradiation is measured and compared with empirical formulae from the literature. Window convection heat transfer is another main area of interest. Nocturnal convective heat transfer from a double pane glazing is studied and measurement principles are discussed. Finally, a compilation of meteorological data for hygrothermal simulations, including estimation of driving rain, is described. System error estimation in relation to the window convection measurements, design notes on an apparatus for external convection measurement, formulae for conversion of relative humitity and dry-bulb temperature into dew point temperature. (EG) 66 refs.

  13. Influence of surface roughness of a desert

    Science.gov (United States)

    Sud, Y. C.; Smith, W. E.

    1984-01-01

    A numerical simulation study, using the current GLAS climate GCM, was carried out to examine the influence of low bulk aerodynamic drag parameter in the deserts. The results illustrate the importance of yet another feedback effect of a desert on itself, that is produced by the reduction in surface roughness height of land once the vegetation dies and desert forms. Apart from affecting the moisture convergence, low bulk transport coefficients of a desert lead to enhanced longwave cooling and sinking which together reduce precipitation by Charney's (1975) mechanism. Thus, this effect, together with albedo and soil moisture influence, perpetuate a desert condition through its geophysical feedback effect. The study further suggests that man made deserts is a viable hypothesis.

  14. Biodiversity losses: The downward spiral

    Science.gov (United States)

    Tomback, Diana F.; Kendall, Katherine C.; Tomback, Diana F.; Arno, Stephen F.; Keane, Robert E.

    2001-01-01

    The dramatic decline of whitebark pine (Pinus albicaulis) populations in the northwestern United States and southwestern Canada from the combined effects of fire exclusion, mountain pine beetles (Dendroctonus ponderosae), and white pine blister rust (Cronartium ribicola), and the projected decline of whitebark pine populations rangewide (Chapters 10 and 11) do not simply add up to local extirpations of a single tree species. Instead, the loss of whitebark pine has broad ecosystem-level consequences, eroding local plant and animal biodiversity, changing the time frame of succession, and altering the distribution of subalpine vegetation (Chapter 1). One potential casualty of this decline may be the midcontinental populations of the grizzly bear (Ursus arctos horribilis), which use whitebark pine seeds as a major food source (Chapter 7). Furthermore, whitebark pine is linked to other white pine ecosystems in the West through its seed-disperser, Clark's nutcracker (Nucifraga columbiana) (Chapter 5). Major declines in nutcracker populations ultimately seal the fate of several white pine ecosystems, and raise the question of whether restoration is possible once a certain threshold of decline is reached.

  15. Rayleigh oscillations localized near free surface of a fcc crystal

    International Nuclear Information System (INIS)

    Kosevich, A.M.; Matsokin, D.V.; Savotchenko, S.E.

    1997-01-01

    The waves, which are localized near the free (001) surface of a fcc crystal and propagate in the [110] direction, are described using the model of central interaction of the nearest neighbors. The frequencies of these waves come into the gaps within the frequency spectrum of bulk harmonic oscillations with a fixed wave vector k component along the surface. The long-wave limit and the case of wave vectors close to the Brillouin band boundary are studied analytically. These limit dependences are in agreement with other authors results which were obtained by numerical methods. Analytical calculations in the limit intervals of k are supplemented by numerical calculations for any values of the wave vector. It is essential that these waves have a displacement component which is perpendicular to the crystal surface and can, therefore, be studied by methods of He atoms inelastic scattering

  16. Dry Deposition, Surface Production and Dynamics of Aerosols in the Marine Boundary Layer

    DEFF Research Database (Denmark)

    Fairall, C.W.; Larsen, Søren Ejling

    1984-01-01

    A model of downward aerosol panicle flux characterized by dry deposition velocity, Vd, due to Slinn and Slinn (1980) is generalized to the case of nonzero surface concentration (absorbing surface with a surface source). A more general expression for the flux at some reference height is developed ...... produced as droplets at the surface and ‘continental’ background aerosols brought into the boundary layer at the top by entrainment and gravitational settling. Estimates of Si are provided....

  17. Bread and Shoulders: Reversing the Downward Spiral, a Qualitative Analyses of the Effects of a Housing First-Type Program in France

    Science.gov (United States)

    Rhenter, Pauline; Moreau, Delphine; Laval, Christian; Mantovani, Jean; Albisson, Amandine; Suderie, Guillaume; Boucekine, Mohamed; Tinland, Aurelie; Loubière, Sandrine; Greacen, Tim; Auquier, Pascal; Girard, Vincent

    2018-01-01

    This paper is a qualitative analysis of the effects of accompagnement, a support framework, on recovery trajectories of people with long-term homelessness and severe psychiatric disorders during 24 months in a Housing First-type program in France. A comprehensive methodology based on grounded theory was used to construct an interview guide, conduct multiple interviews with 35 Housing First participants sampled for heterogeneity, and produce memos on their trajectories before and after entering the program based on interview information. Thematic analysis of a representative subsample (n = 13) of memos identified 12 objective factors and 6 subjective factors key to the recovery process. An in-depth re-analysis of the memos generated four recovery themes: (1) the need for secure space favorable to self-reflexivity; (2) a “honeymoon” effect; (3) the importance of even weak social ties; (4) support from and hope among peers. Three challenges to recovery were identified: (1) finding a balance between protection and risk; (2) breaking downward spirals; (3) bifurcating the trajectory. This study provides new insight into the recovery process, understood as a non-linear transformation of an experience—the relationship between objective life conditions and subjective perception of those conditions—which reinforces protective support over risk elements. PMID:29538346

  18. Disrupting the downward spiral of chronic pain and opioid addiction with mindfulness-oriented recovery enhancement: a review of clinical outcomes and neurocognitive targets.

    Science.gov (United States)

    Garland, Eric L

    2014-06-01

    Prescription opioid misuse and addiction among chronic pain patients are problems of growing medical and social significance. Chronic pain patients often require intervention to improve their well-being and functioning, and yet, the most commonly available form of pharmacotherapy for chronic pain is centered on opioid analgesics--drugs that have high abuse liability. Consequently, health care and legal systems are often stymied in their attempts to intervene with individuals who suffer from both pain and addiction. As such, novel, nonpharmacologic interventions are needed to complement pharmacotherapy and interrupt the cycle of behavioral escalation. The purpose of this paper is to describe how the downward spiral of chronic pain and prescription opioid misuse may be targeted by one such intervention, Mindfulness-Oriented Recovery Enhancement (MORE), a new behavioral treatment that integrates elements from mindfulness training, cognitive-behavioral therapy, and positive psychology. The clinical outcomes and neurocognitive mechanisms of this intervention are reviewed with respect to their effects on the risk chain linking chronic pain and prescription opioid misuse. Future directions for clinical and pharmacologic research are discussed.

  19. Bread and Shoulders: Reversing the Downward Spiral, a Qualitative Analyses of the Effects of a Housing First-Type Program in France

    Directory of Open Access Journals (Sweden)

    Pauline Rhenter

    2018-03-01

    Full Text Available This paper is a qualitative analysis of the effects of accompagnement, a support framework, on recovery trajectories of people with long-term homelessness and severe psychiatric disorders during 24 months in a Housing First-type program in France. A comprehensive methodology based on grounded theory was used to construct an interview guide, conduct multiple interviews with 35 Housing First participants sampled for heterogeneity, and produce memos on their trajectories before and after entering the program based on interview information. Thematic analysis of a representative subsample (n = 13 of memos identified 12 objective factors and 6 subjective factors key to the recovery process. An in-depth re-analysis of the memos generated four recovery themes: (1 the need for secure space favorable to self-reflexivity; (2 a “honeymoon” effect; (3 the importance of even weak social ties; (4 support from and hope among peers. Three challenges to recovery were identified: (1 finding a balance between protection and risk; (2 breaking downward spirals; (3 bifurcating the trajectory. This study provides new insight into the recovery process, understood as a non-linear transformation of an experience—the relationship between objective life conditions and subjective perception of those conditions—which reinforces protective support over risk elements.

  20. A Dual Conductance Sensor for Simultaneous Measurement of Void Fraction and Structure Velocity of Downward Two-Phase Flow in a Slightly Inclined Pipe.

    Science.gov (United States)

    Lee, Yeon-Gun; Won, Woo-Youn; Lee, Bo-An; Kim, Sin

    2017-05-08

    In this study, a new and improved electrical conductance sensor is proposed for application not only to a horizontal pipe, but also an inclined one. The conductance sensor was designed to have a dual layer, each consisting of a three-electrode set to obtain two instantaneous conductance signals in turns, so that the area-averaged void fraction and structure velocity could be measured simultaneously. The optimum configuration of the electrodes was determined through numerical analysis, and the calibration curves for stratified and annular flow were obtained through a series of static experiments. The fabricated conductance sensor was applied to a 45 mm inner diameter U-shaped downward inclined pipe with an inclination angle of 3° under adiabatic air-water flow conditions. In the tests, the superficial velocities ranged from 0.1 to 3.0 m/s for water and from 0.1 to 18 m/s for air. The obtained mean void fraction and the structure velocity from the conductance sensor were validated against the measurement by the wire-mesh sensor and the cross-correlation technique for the visualized images, respectively. The results of the flow regime classification and the corresponding time series of the void fraction at a variety of flow velocities were also discussed.

  1. Bread and Shoulders: Reversing the Downward Spiral, a Qualitative Analyses of the Effects of a Housing First-Type Program in France.

    Science.gov (United States)

    Rhenter, Pauline; Moreau, Delphine; Laval, Christian; Mantovani, Jean; Albisson, Amandine; Suderie, Guillaume; Boucekine, Mohamed; Tinland, Aurelie; Loubière, Sandrine; Greacen, Tim; Auquier, Pascal; Girard, Vincent

    2018-03-14

    This paper is a qualitative analysis of the effects of accompagnement , a support framework, on recovery trajectories of people with long-term homelessness and severe psychiatric disorders during 24 months in a Housing First-type program in France. A comprehensive methodology based on grounded theory was used to construct an interview guide, conduct multiple interviews with 35 Housing First participants sampled for heterogeneity, and produce memos on their trajectories before and after entering the program based on interview information. Thematic analysis of a representative subsample ( n = 13) of memos identified 12 objective factors and 6 subjective factors key to the recovery process. An in-depth re-analysis of the memos generated four recovery themes: (1) the need for secure space favorable to self-reflexivity; (2) a "honeymoon" effect; (3) the importance of even weak social ties; (4) support from and hope among peers. Three challenges to recovery were identified: (1) finding a balance between protection and risk; (2) breaking downward spirals; (3) bifurcating the trajectory. This study provides new insight into the recovery process, understood as a non-linear transformation of an experience-the relationship between objective life conditions and subjective perception of those conditions-which reinforces protective support over risk elements.

  2. A Strange Case of Downward Displacement of a Deep Brain Stimulation Electrode 10 Years Following Implantation: The Gliding Movement of Snakes Theory.

    Science.gov (United States)

    Iacopino, Domenico Gerardo; Maugeri, Rosario; Giugno, Antonella; Giller, Cole A

    2015-08-01

    Despite the best efforts to ensure stereotactic precision, deep brain stimulation (DBS) electrodes can wander from their intended position after implantation. We report a case of downward electrode migration 10 years following successful implantation in a patient with Parkinson disease. A 53-year-old man with Parkinson disease underwent bilateral implantation of DBS electrodes connected to a subclavicular 2-channel pulse generator. The generator was replaced 7 years later, and a computed tomography (CT) scan confirmed the correct position of both leads. The patient developed a gradual worsening affecting his right side 3 years later, 10 years after the original implantation. A CT scan revealed displacement of the left electrode inferiorly into the pons. The new CT scans and the CT scans obtained immediately after the implantation were merged within a stereotactic planning workstation (Brainlab). Comparing the CT scans, the distal end of the electrode was in the same position, the proximal tip being significantly more inferior. The size and configuration of the coiled portions of the electrode had not changed. At implantation, the length was 27.7 cm; after 10 years, the length was 30.6 cm. These data suggests that the electrode had been stretched into its new position rather than pushed. Clinicians evaluating patients with a delayed worsening should be aware of this rare event. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

    Science.gov (United States)

    Mulligan, Kevin; Towler, Brett; Haro, Alexander J.; Ahlfeld, David P.

    2017-01-01

    Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity to the sweeping velocity magnitude changes along the full length and depth of a guide wall under a wide range of bypass flow percentages within a power canal. This paper focused on two guide wall configurations, each set at an angle of 45 ° to the approaching flow field and at a depth of 10 and 20 ft (3.05 and 6.10 m). The hydraulic conditions upstream of each guide wall configuration were shown to be impacted by a change in the bypass flow percentage, not only near the bypass but also at upstream sections of the guide wall. Furthermore, the effect of changing the bypass flow percentage was similar for both guide wall depths. In both cases, the effect of increasing the bypass flow percentage was magnified closer to the bypass and deeper in the water column along the guide wall.

  4. Surface spectral emissivity derived from MODIS data

    Science.gov (United States)

    Chen, Yan; Sun-Mack, Sunny; Minnis, Patrick; Smith, William L.; Young, David F.

    2003-04-01

    Surface emissivity is essential for many remote sensing applications including the retrieval of the surface skin temperature from satellite-based infrared measurements, determining thresholds for cloud detection and for estimating the emission of longwave radiation from the surface, an important component of the energy budget of the surface-atmosphere interface. In this paper, data from the Terra MODIS (MODerate-resolution Imaging Spectroradiometer) taken at 3.7, 8.5, 10.8, 12.0 micron are used to simultaneously derive the skin temperature and the surface emissivities at the same wavelengths. The methodology uses separate measurements of the clear-sky temperatures that are determined by the CERES (Clouds and Earth's Radiant Energy System) scene classification in each channel during the daytime and at night. The relationships between the various channels at night are used during the day when solar reflectance affects the 3.7 micron data. A set of simultaneous equations is then solved to derive the emissivities. Global results are derived from MODIS. Numerical weather analyses are used to provide soundings for correcting the observed radiances for atmospheric absorption. These results are verified and will be available for remote sensing applications.

  5. Three modes of interdecadal trends in sea surface temperature and sea surface height

    Science.gov (United States)

    Gnanadesikan, A.; Pradal, M.

    2013-12-01

    It might be thought that sea surface height and sea surface temperature would be tightly related. We show that this is not necessarily the case on a global scale. We analysed this relationship in a suite of coupled climate models run under 1860 forcing conditions. The models are low-resolution variants of the GFDL Earth System Model, reported in Galbraith et al. (J. Clim. 2011). 1. Correlated changes in global sea surface height and global sea surface temperature. This mode corresponds to opening and closing of convective chimneys in the Southern Ocean. As the Southern Ocean destratifies, sea ice formation is suppressed during the winter and more heat is taken up during the summer. This mode of variability is highly correlated with changes in the top of the atmosphere radiative budget and weakly correlated with changes in the deep ocean circulation. 2. Uncorrelated changes in global sea surface height and global sea surface temperature. This mode of variability is associated with interdecadal variabliity in tropical winds. Changes in the advective flux of heat to the surface ocean play a critical role in driving these changes, which also result in significant local changes in sea level. Changes sea ice over the Southern Ocean still result in changes in solar absorption, but these are now largely cancelled by changes in outgoing longwave radiation. 3. Anticorrelated changes in global sea surface height and global sea surface temperatures. By varying the lateral diffusion coefficient in the ocean model, we are able to enhance and suppress convection in the Southern and Northern Pacific Oceans. Increasing the lateral diffusion coefficients shifts the balance sources of deep water away from the warm salty deep water of the North Atlantic and towards cold fresh deep water from the other two regions. As a result, even though the planet as a whole warms, the deep ocean cools and sea level falls, with changes of order 30 cm over 500 years. The increase in solar absorption

  6. Global scale variability of the mineral dust long-wave refractive index: a new dataset of in situ measurements for climate modeling and remote sensing

    Science.gov (United States)

    Di Biagio, Claudia; Formenti, Paola; Balkanski, Yves; Caponi, Lorenzo; Cazaunau, Mathieu; Pangui, Edouard; Journet, Emilie; Nowak, Sophie; Caquineau, Sandrine; Andreae, Meinrat O.; Kandler, Konrad; Saeed, Thuraya; Piketh, Stuart; Seibert, David; Williams, Earle; Doussin, Jean-François

    2017-02-01

    Modeling the interaction of dust with long-wave (LW) radiation is still a challenge because of the scarcity of information on the complex refractive index of dust from different source regions. In particular, little is known about the variability of the refractive index as a function of the dust mineralogical composition, which depends on the specific emission source, and its size distribution, which is modified during transport. As a consequence, to date, climate models and remote sensing retrievals generally use a spatially invariant and time-constant value for the dust LW refractive index. In this paper, the variability of the mineral dust LW refractive index as a function of its mineralogical composition and size distribution is explored by in situ measurements in a large smog chamber. Mineral dust aerosols were generated from 19 natural soils from 8 regions: northern Africa, the Sahel, eastern Africa and the Middle East, eastern Asia, North and South America, southern Africa, and Australia. Soil samples were selected from a total of 137 available samples in order to represent the diversity of sources from arid and semi-arid areas worldwide and to account for the heterogeneity of the soil composition at the global scale. Aerosol samples generated from soils were re-suspended in the chamber, where their LW extinction spectra (3-15 µm), size distribution, and mineralogical composition were measured. The generated aerosol exhibits a realistic size distribution and mineralogy, including both the sub- and super-micron fractions, and represents in typical atmospheric proportions the main LW-active minerals, such as clays, quartz, and calcite. The complex refractive index of the aerosol is obtained by an optical inversion based upon the measured extinction spectrum and size distribution. Results from the present study show that the imaginary LW refractive index (k) of dust varies greatly both in magnitude and spectral shape from sample to sample, reflecting the

  7. Long-Wave Radiation Divergence over Water and Land from Measurement and Calculation (Die Langwellige Strahlungsdivergenz ueber Wasser und ueber dem Festen Boden nach Messung und Rechnung),

    Science.gov (United States)

    surface temperature field. If these are eliminated, which is relatively simple over a water surface, the differences between calculated and measured...divergences at these levels is less than 20%, on the average. The relative variation of the divergence with height is somewhat greater over water than over land, due to the different temperature profiles. (Author)

  8. Radionuclide transfer onto ground surface in surface water flow, 1

    International Nuclear Information System (INIS)

    Mukai, Masayuki; Takebe, Shinichi; Komiya, Tomokazu; Kamiyama, Hideo

    1991-07-01

    Radionuclides migration in ground surface water flow is considered to be one of the important path way in the scenario for environmental migration of radionuclides leaked from low level radioactive waste repository. Simulating the slightly sloped surface on which contaminated solution is flowing downward, testing for radionuclide migration on ground surface had been started. As it's first step, an experiment was carried out under the condition of restricted infiltration in order to elucidate the adsorption behavior of radionuclides onto the loamy soil surface in related with hydraulic conditions. Radionuclides concentration change in effluent solution with time and a concentration distribution of radionuclides adsorbed on the ground surface were obtained from several experimental conditions combining the rate and the duration time of the water flow. The radionuclides concentration in the effluent solution was nearly constant during each experimental period, and was reduced under the condition of lower flow rate. The surface distribution of radionuclides concentration showed two distinctive regions. The one was near the inlet vessel where the concentration was promptly reducing, and the other was following the former where the concentration was nearly constant. The characteristic surface distribution of radionuclides concentration can be explained by a two dimensional diffusion model with a first order adsorption reaction, based on the advection of flow rate distribution in perpendicular direction. (author)

  9. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores

  10. An Improved Method For Retrieving Land Surface Albedo Over Rugged Terrain

    NARCIS (Netherlands)

    Gao, B.; Jia, L.; Menenti, M.

    2014-01-01

    Land surface albedo is a very important parameter, which can be derived from a bidirectional reflectance distribution function (BRDF) model with angular integration of BRDF in a particular distribution of downward solar irradiance. The Algorithm for MODIS Bidirectional Reflectance Anisotropic of

  11. Modeling the downward transport of {sup 210}Pb in Peatlands: Initial Penetration‐Constant Rate of Supply (IP-CRS) model

    Energy Technology Data Exchange (ETDEWEB)

    Olid, Carolina, E-mail: olid.carolina@gmail.com [Department of Ecology and Environmental Science, Umeå University, SE-90187, Umeå (Sweden); Diego, David [Department of Earth Science, University of Bergen, NO-5020 Bergen (Norway); Garcia-Orellana, Jordi [Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Cortizas, Antonio Martínez [Departamento de Edafoloxía e Química Agrícola, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Klaminder, Jonatan [Department of Ecology and Environmental Science, Umeå University, SE-90187, Umeå (Sweden)

    2016-01-15

    The vertical distribution of {sup 210}Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of {sup 210}Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from {sup 210}Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived {sup 210}Pb ({sup 210}Pb{sub xs}) in peat taking into account both incorporation of {sup 210}Pb into the accumulating peat matrix as well as an initial flushing of {sup 210}Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous {sup 210}Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used {sup 210}Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. {sup 241}Am and {sup 137}Cs). Our results showed that the IP-CRS can provide chronologies from peat records where {sup 210}Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene. - Highlights: • Accurate age dating of peat and sediment cores is critical for evaluating change. • A new {sup 210}Pb dating model that includes vertical transport of {sup 210}Pb was developed. • The IP-CRS model provided consistent peat accumulation rates. • The IP-CRS ages were consistent with independent chronological markers. • The IP-CRS model derives peat ages where downward {sup 210}Pb transport is

  12. Long-term changes in net radiation and its components above a pine forest and a grass surface in Germany

    International Nuclear Information System (INIS)

    Kessler, A.; Jaeger, L.

    1999-01-01

    Long-term measurements (1974–1993 and 1996, respectively) of the net radiation (Q), global radiation (G), reflected global radiation (R), long-wave atmospheric radiation (A) and thermal radiation (E) of a pine forest in Southern Germany (index p) and of a grass surface in Northern Germany (index g) are compared. The influence of changes in surface properties is discussed. There are, in the case of the pine stand, forest growth and forest management and in the case of the grass surface, the shifting of the site from a climatic garden to a horizontal roof. Both series of radiant fluxes are analyzed with respect to the influences of the weather (cloudiness, heat advection). To eliminate the different influence of the solar radiation of the two sites, it is necessary to normalize by means of the global radiation G, yielding the radiation efficiency Q/G, the albedo R/G=α and the normalized long-wave net radiation (A+E)/G. Furthermore, the long-term mean values and the long-term trend of yearly mean values are discussed and, moreover, a comparison is made of individual monthly values. Q p is twice as large as Q g . The reason for this is the higher values of G and A above the pine forest and half values of α p compared to α g . E p is only a little greater than E g . The time series of the radiation fluxes show the following trends: Q p declines continuously despite a slight increase of G p . This is mainly due to the long-wave radiation fluxes. The net radiation of the grass surface Q g shows noticeably lower values after the merging of the site. This phenomenon is also dominated by the long-wave radiation processes. Although the properties of both site surfaces alter, E p and E g remain relatively stable. A p and A g show a remarkable decrease however. The reason for this is to be found in a modification of the heat advection, showing a more pronounced impact on the more continentally exposed site (pine forest). Compared to α g , α p shows only a small

  13. Surface Water & Surface Drainage

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  14. Surface correlations of hydrodynamic drag for transitionally rough engineering surfaces

    Science.gov (United States)

    Thakkar, Manan; Busse, Angela; Sandham, Neil

    2017-02-01

    Rough surfaces are usually characterised by a single equivalent sand-grain roughness height scale that typically needs to be determined from laboratory experiments. Recently, this method has been complemented by a direct numerical simulation approach, whereby representative surfaces can be scanned and the roughness effects computed over a range of Reynolds number. This development raises the prospect over the coming years of having enough data for different types of rough surfaces to be able to relate surface characteristics to roughness effects, such as the roughness function that quantifies the downward displacement of the logarithmic law of the wall. In the present contribution, we use simulation data for 17 irregular surfaces at the same friction Reynolds number, for which they are in the transitionally rough regime. All surfaces are scaled to the same physical roughness height. Mean streamwise velocity profiles show a wide range of roughness function values, while the velocity defect profiles show a good collapse. Profile peaks of the turbulent kinetic energy also vary depending on the surface. We then consider which surface properties are important and how new properties can be incorporated into an empirical model, the accuracy of which can then be tested. Optimised models with several roughness parameters are systematically developed for the roughness function and profile peak turbulent kinetic energy. In determining the roughness function, besides the known parameters of solidity (or frontal area ratio) and skewness, it is shown that the streamwise correlation length and the root-mean-square roughness height are also significant. The peak turbulent kinetic energy is determined by the skewness and root-mean-square roughness height, along with the mean forward-facing surface angle and spanwise effective slope. The results suggest feasibility of relating rough-wall flow properties (throughout the range from hydrodynamically smooth to fully rough) to surface

  15. Influence of surface oxidation on the radiative properties of ZrB{sub 2}-SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ning, E-mail: lncaep@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (China); Xing, Pifeng; Li, Cui [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (China); Wang, Peng [School of Material Science and Engineering, Shandong University of Technology, Zibo 255049 (China); Jin, Xinxin [College of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040 (China); Zhang, Xinghong [Science and Technology on Advanced Composites in Special Environments Laboratory, Harbin Institute of Technology, Harbin 150001 (China)

    2017-07-01

    Highlights: • Surface component affected radiative properties of ZrB{sub 2}-SiC composites significantly. • Emissivity in long-wave range gradually increased with the thickness of oxide scale. • The surface temperature had a little effect on radiative properties of composites. • Influence of surface roughness on emissivity could be negligible. • Covering the surface with glass is a method for improving radiative properties. - Abstract: The spectral emissivities of ZrB{sub 2}-20 vol.% SiC composites with various surface components of ZrB{sub 2}/SiC (ZS1), silica-rich glass (ZS2) and porous zirconia (ZS3) were measured using infrared spectrometer in the wavelength range from 2.5 to 25.0 μm. The relationship between surface oxidation (associated with surface component, thickness of oxide scale, testing temperature as well as roughness) and the radiative properties of ZrB{sub 2}-SiC composites were investigated systematically. Surface component affected the radiative properties of composites significantly. The total emissivity of ZS1 varied from 0.22 to 0.81 accompanied with surface oxidation in the temperature range 300–900 °C. The emissivity of ZS2 was about 1.5 times as that of ZS3 under the same testing conditions. The oxide scale on specimen surface enhanced the radiative properties especially in terms of short-wave range, and the emissivity in the long-wave range gradually increased with the thickness of oxide scale within a certain range. The influence of testing temperature and surface roughness was also investigated. The testing temperature had a little effect on radiative properties, whereas effect of surface roughness could be negligible.

  16. An investigation of the sensitivity of a land surface model to climate change using a reduced form model

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, A.H.; McIlwaine, S. [PAOS/CIRES, Univ. of Colorado, Boulder, CO (United States); Beringer, J. [Inst. of Arctic Biology, Univ. of Alaska, Fairbanks (United States); Bonan, G.B. [National Center for Atmospheric Research, Boulder, CO (United States)

    2001-05-01

    In an illustration of a model evaluation methodology, a multivariate reduced form model is developed to evaluate the sensitivity of a land surface model to changes in atmospheric forcing. The reduced form model is constructed in terms of a set of ten integrative response metrics, including the timing of spring snow melt, sensible and latent heat fluxes in summer, and soil temperature. The responses are evaluated as a function of a selected set of six atmospheric forcing perturbations which are varied simultaneously, and hence each may be thought of as a six-dimensional response surface. The sensitivities of the land surface model are interdependent and in some cases illustrate a physically plausible feedback process. The important predictors of land surface response in a changing climate are the atmospheric temperature and downwelling longwave radiation. Scenarios characterized by warming and drying produce a large relative response compared to warm, moist scenarios. The insensitivity of the model to increases in precipitation and atmospheric humidity is expected to change in applications to coupled models, since these parameters are also strongly implicated, through the representation of clouds, in the simulation of both longwave and shortwave radiation. (orig.)

  17. The long-term Global LAnd Surface Satellite (GLASS) product suite and applications

    Science.gov (United States)

    Liang, S.

    2015-12-01

    Our Earth's environment is experiencing rapid changes due to natural variability and human activities. To monitor, understand and predict environment changes to meet the economic, social and environmental needs, use of long-term high-quality satellite data products is critical. The Global LAnd Surface Satellite (GLASS) product suite, generated at Beijing Normal University, currently includes 12 products, including leaf area index (LAI), broadband shortwave albedo, broadband longwave emissivity, downwelling shortwave radiation and photosynthetically active radiation, land surface skin temperature, longwave net radiation, daytime all-wave net radiation, fraction of absorbed photosynetically active radiation absorbed by green vegetation (FAPAR), fraction of green vegetation coverage, gross primary productivity (GPP), and evapotranspiration (ET). Most products span from 1981-2014. The algorithms for producing these products have been published in the top remote sensing related journals and books. More and more applications have being reported in the scientific literature. The GLASS products are freely available at the Center for Global Change Data Processing and Analysis of Beijing Normal University (http://www.bnu-datacenter.com/), and the University of Maryland Global Land Cover Facility (http://glcf.umd.edu). After briefly introducing the basic characteristics of GLASS products, we will present some applications on the long-term environmental changes detected from GLASS products at both global and local scales. Detailed analysis of regional hotspots, such as Greenland, Tibetan plateau, and northern China, will be emphasized, where environmental changes have been mainly associated with climate warming, drought, land-atmosphere interactions, and human activities.

  18. Future projections of the Greenland ice sheet energy balance driving the surface melt

    Directory of Open Access Journals (Sweden)

    B. Franco

    2013-01-01

    Full Text Available In this study, simulations at 25 km resolution are performed over the Greenland ice sheet (GrIS throughout the 20th and 21st centuries, using the regional climate model MAR forced by four RCP scenarios from three CMIP5 global circulation models (GCMs, in order to investigate the projected changes of the surface energy balance (SEB components driving the surface melt. Analysis of 2000–2100 melt anomalies compared to melt results over 1980–1999 reveals an exponential relationship of the GrIS surface melt rate simulated by MAR to the near-surface air temperature (TAS anomalies, mainly due to the surface albedo positive feedback associated with the extension of bare ice areas in summer. On the GrIS margins, the future melt anomalies are preferentially driven by stronger sensible heat fluxes, induced by enhanced warm air advection over the ice sheet. Over the central dry snow zone, the surface albedo positive feedback induced by the increase in summer melt exceeds the negative feedback of heavier snowfall for TAS anomalies higher than 4 °C. In addition to the incoming longwave flux increase associated with the atmosphere warming, GCM-forced MAR simulations project an increase of the cloud cover decreasing the ratio of the incoming shortwave versus longwave radiation and dampening the albedo feedback. However, it should be noted that this trend in the cloud cover is contrary to that simulated by ERA-Interim–forced MAR for recent climate conditions, where the observed melt increase since the 1990s seems mainly to be a consequence of more anticyclonic atmospheric conditions. Finally, no significant change is projected in the length of the melt season, which highlights the importance of solar radiation absorbed by the ice sheet surface in the melt SEB.

  19. Evaluating Surface Radiation Fluxes Observed From Satellites in the Southeastern Pacific Ocean

    Science.gov (United States)

    Pinker, R. T.; Zhang, B.; Weller, R. A.; Chen, W.

    2018-03-01

    This study is focused on evaluation of current satellite and reanalysis estimates of surface radiative fluxes in a climatically important region. It uses unique observations from the STRATUS Ocean Reference Station buoy in a region of persistent marine stratus clouds 1,500 km off northern Chile during 2000-2012. The study shows that current satellite estimates are in better agreement with buoy observations than model outputs at a daily time scale and that satellite data depict well the observed annual cycle in both shortwave and longwave surface radiative fluxes. Also, buoy and satellite estimates do not show any significant trend over the period of overlap or any interannual variability. This verifies the stability and reliability of the satellite data and should make them useful to examine El Niño-Southern Oscillation variability influences on surface radiative fluxes at the STRATUS site for longer periods for which satellite record is available.

  20. NASA/GEWEX Surface Radiation Budget: Integrated Data Product With Reprocessed Radiance, Cloud, and Meteorology Inputs, and New Surface Albedo Treatment

    Science.gov (United States)

    Cox, Stephen J.; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Mikovitz, J. Colleen; Zhang, Taiping

    2016-01-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The current release 3.0 (available at gewex-srb.larc.nasa.gov) uses the International Satellite Cloud Climatology Project (ISCCP) DX product for pixel level radiance and cloud information. This product is subsampled to 30 km. ISCCP is currently recalibrating and recomputing their entire data series, to be released as the H product, at 10km resolution. The ninefold increase in pixel number will allow SRB a higher resolution gridded product (e.g. 0.5 degree), as well as the production of pixel-level fluxes. In addition to the input data improvements, several important algorithm improvements have been made. Most notable has been the adaptation of Angular Distribution Models (ADMs) from CERES to improve the initial calculation of shortwave TOA fluxes, from which the surface flux calculations follow. Other key input improvements include a detailed aerosol history using the Max Planck Institut Aerosol Climatology (MAC), temperature and moisture profiles from HIRS, and new topography, surface type, and snow/ice. Here we present results for the improved GEWEX Shortwave and Longwave algorithm (GSW and GLW) with new ISCCP data, the various other improved input data sets and the incorporation of many additional internal SRB model improvements. As of the time of abstract submission, results from 2007 have been produced with ISCCP H availability the limiting factor. More SRB data will be produced as ISCCP reprocessing continues. The SRB data produced will be released as part of the Release 4.0 Integrated Product, recognizing the interdependence of the radiative fluxes with other GEWEX products providing estimates of the Earth's global water and energy cycle (I.e., ISCCP, SeaFlux, LandFlux, NVAP, etc.).

  1. A Stabilizing Feedback Between Cloud Radiative Effects and Greenland Surface Melt: Verification From Multi-year Automatic Weather Station Measurements

    Science.gov (United States)

    Zender, C. S.; Wang, W.; van As, D.

    2017-12-01

    Clouds have strong impacts on Greenland's surface melt through the interaction with the dry atmosphere and reflective surfaces. However, their effects are uncertain due to the lack of in situ observations. To better quantify cloud radiative effects (CRE) in Greenland, we analyze and interpret multi-year radiation measurements from 30 automatic weather stations encompassing a broad range of climatological and topographical conditions. During melt season, clouds warm surface over most of Greenland, meaning the longwave greenhouse effect outweighs the shortwave shading effect; on the other hand, the spatial variability of net (longwave and shortwave) CRE is dominated by shortwave CRE and in turn by surface albedo, which controls the potential absorption of solar radiation when clouds are absent. The net warming effect decreases with shortwave CRE from high to low altitudes and from north to south (Fig. 1). The spatial correlation between albedo and net CRE is strong (r=0.93, palbedo determines the net CRE seasonal trend, which decreases from May to July and increases afterwards. On an hourly timescale, we find two distinct radiative states in Greenland (Fig. 2). The clear state is characterized by clear-sky conditions or thin clouds, when albedo and solar zenith angle (SZA) weakly correlates with CRE. The cloudy state is characterized by opaque clouds, when the combination of albedo and SZA strongly correlates with CRE (r=0.85, palbedo and solar zenith angle, explains the majority of the CRE variation in spatial distribution, seasonal trend in the ablation zone, and in hourly variability in the cloudy radiative state. Clouds warm the brighter and colder surfaces of Greenland, enhance snow melt, and tend to lower the albedo. Clouds cool the darker and warmer surfaces, inhibiting snow melt, which increases albedo, and thus stabilizes surface melt. This stabilizing mechanism may also occur over sea ice, helping to forestall surface melt as the Arctic becomes dimmer.

  2. Marangoni instability in a thin film heated from below: Effect of nonmonotonic dependence of surface tension on temperature

    Science.gov (United States)

    Sarma, Rajkumar; Mondal, Pranab Kumar

    2018-04-01

    We investigate Marangoni instability in a thin liquid film resting on a substrate of low thermal conductivity and separated from the surrounding gas phase by a deformable free surface. Considering a nonmonotonic variation of surface tension with temperature, here we analytically derive the neutral stability curve for the monotonic and oscillatory modes of instability (for both the long-wave and short-wave perturbations) under the framework of linear stability analysis. For the long-wave instability, we derive a set of amplitude equations using the scaling k ˜(Bi) 1 /2 , where k is the wave number and Bi is the Biot number. Through this investigation, we demonstrate that for such a fluid layer upon heating from below, both monotonic and oscillatory instability can appear for a certain range of the dimensionless parameters, viz., Biot number (Bi ) , Galileo number (Ga ) , and inverse capillary number (Σ ) . Moreover, we unveil, through this study, the influential role of the above-mentioned parameters on the stability of the system and identify the critical values of these parameters above which instability initiates in the liquid layer.

  3. Regional difference of the vertical structure of seasonal thermocline and its impact on sea surface temperature in the North Pacific

    Science.gov (United States)

    Yamaguchi, R.; Suga, T.

    2016-12-01

    Recent observational studies show that, during the warming season, a large amount of heat flux is penetrated through the base of thin mixed layer by vertical eddy diffusion, in addition to penetration of solar radiation [1]. In order to understand this heat penetration process due to vertical eddy diffusivity and its contribution to seasonal variation of sea surface temperature, we investigated the evolution of thermal stratification below the summertime thin mixed layer (i.e. evolution of seasonal thermocline) and its vertical structure in the North Pacific using high vertical resolution temperature profile observed by Argo floats. We quantified the vertical structure of seasonal thermocline as deviations from the linear structure where the vertical gradient of temperature is constant, that is, "shape anomaly". The shape anomaly is variable representing the extent of the bend of temperature profiles. We found that there are larger values of shape anomaly in the region where the seasonal sea surface temperature warming is relatively faster. To understand the regional difference of shape anomalies, we investigated the relationship between time changes in shape anomalies and net surface heat flux and surface kinetic energy flux. From May to July, the analysis indicated that, in a large part of North Pacific, there's a tendency for shape anomalies to develop strongly (weakly) under the conditions of large (small) downward net surface heat flux and small (large) downward surface kinetic energy flux. Since weak (strong) development of shape anomalies means efficient (inefficient) downward heat transport from the surface, these results suggest that the regional difference of the downward heat penetration below mixed layer is explained reasonably well by differences in surface heat forcing and surface wind forcing in a vertical one dimensional framework. [1] Hosoda et al. (2015), J. Oceanogr., 71, 541-556.

  4. Preliminary analysis of surface radiation measurements recorded at the Nansen ice sheet (Antarctica)

    International Nuclear Information System (INIS)

    Bonafe', U.; Dalpane, E.; Georgiadis, T.; Pitacco, A.

    1996-01-01

    An experiment on radiation and surface energy balance was conducted during the 9. Italian expedition in Antarctica at the Nancen ice sheet, a glacier situated close to the Italian base at Terra Nova Bay, to correlate surface balances to the formation and development of katabatic winds. Measurements were taken by radiometers covering the whole spectra of solar and terrestrial emissions and by fast sensors of atmospheric wind velocity and humidity for the application of the eddy correlation technique. A preliminary analysis of the radiometric data collected in order to quantify the major components of radiative energy balance during the Antarctic summer in clear sky conditions is reported and discussed. The findings show the very low available energy (mean about 1 W/m 2 ), in terms of net radiation, for the physical processes such as sensible- and latent-heat fluxes. Long-wave radiation balance was applied to estimate the reliability of the Swinbank's parametrization, relative to general conditions of the atmosphere

  5. Evaluation of Arctic broadband surface radiation measurements

    Science.gov (United States)

    Matsui, N.; Long, C. N.; Augustine, J.; Halliwell, D.; Uttal, T.; Longenecker, D.; Niebergall, O.; Wendell, J.; Albee, R.

    2012-02-01

    The Arctic is a challenging environment for making in-situ surface radiation measurements. A standard suite of radiation sensors is typically designed to measure incoming and outgoing shortwave (SW) and thermal infrared, or longwave (LW), radiation. Enhancements may include various sensors for measuring irradiance in narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers) that keep sensors and shading devices trained on the sun along its diurnal path. High quality measurements require striking a balance between locating stations in a pristine undisturbed setting free of artificial blockage (such as from buildings and towers) and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data in the Arctic include solar tracker malfunctions, rime/frost/snow deposition on the protective glass domes of the radiometers and operational problems due to limited operator access in extreme weather conditions. In this study, comparisons are made between the global and component sum (direct [vertical component] + diffuse) SW measurements. The difference between these two quantities (that theoretically should be zero) is used to illustrate the magnitude and seasonality of arctic radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both SW and LW measurements. Solutions to these operational problems that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols are proposed.

  6. The World Radiation Monitoring Center of the Baseline Surface Radiation Network: Status 2017

    Science.gov (United States)

    Driemel, Amelie; König-Langlo, Gert; Sieger, Rainer; Long, Charles N.

    2017-04-01

    The World Radiation Monitoring Center (WRMC) is the central archive of the Baseline Surface Radiation Network (BSRN). The BSRN was initiated by the World Climate Research Programme (WCRP) Working Group on Radiative Fluxes and began operations in 1992. One of its aims is to provide short and long-wave surface radiation fluxes of the best possible quality to support the research projects of the WCRP and other scientific projects. The high quality, uniform and consistent measurements of the BSRN network can be used to monitor the short- and long-wave radiative components and their changes with the best methods currently available, to validate and evaluate satellite-based estimates of the surface radiative fluxes, and to verify the results of global climate models. In 1992 the BSRN/WRMC started at ETH Zurich, Switzerland with 9 stations. Since 2007 the archive is hosted by the Alfred-Wegener-Institut (AWI) in Bremerhaven, Germany (http://www.bsrn.awi.de/) and comprises a network of currently 59 stations in contrasting climatic zones, covering a latitude range from 80°N to 90°S. Of the 59 stations, 23 offer the complete radiation budget (down- and upwelling short- and long-wave data). In addition to the ftp-service access instituted at ETH Zurich, the archive at AWI offers data access via PANGAEA - Data Publisher for Earth & Environmental Science (https://www.pangaea.de). PANGAEA guarantees the long-term availability of its content through a commitment of the operating institutions. Within PANGAEA, the metadata of the stations are freely available. To access the data itself an account is required. If the scientist accepts to follow the data release guidelines of the archive (http://bsrn.awi.de/data/conditions-of-data-release/) he or she can get an account from amelie.driemel@awi.de. Currently, more than 9,400 station months (>780 years) are available for interested scientists (see also https://dataportals.pangaea.de/bsrn/?q=LR0100 for an overview on available data

  7. Sky glint correction in measurements of upward radiance above the sea surface

    Directory of Open Access Journals (Sweden)

    Jerzy Olszewski

    2000-06-01

    Full Text Available An experiment has been performed to determine the upward water-leaving radiance by non-contact measurement of the total upward and downward radiance above the sea surface from a moving ship. The method for achieving this aim is described: the radiance meters are both tilted in such a way that the upward radiance meter can 'see' that part of the measured downward radiance which would be reflected if the water surface were smooth and which is not derived directly from solar glitter. Both meters are firmly fixed in a special frame, which ensures that the required orientation is the most probable one. Time records of the measured parameters are analysed. The results are presented in several forms: frequency (histogram analysis appears to be the most promising one.

  8. The influence of the speed of the down-ward leader channel in computation of additional charge for protection against direct lightning strike by charge transfer system in 'ultra-corona' mode

    International Nuclear Information System (INIS)

    Talevski, V.

    2012-01-01

    In this paper computation of additional charge is done for protection against direct lightning strike, by charge transfer system, by point electrode, in 'ultra-corona' mode. The influence of the voltage increase in a very small time interval is computed and the influence is taken into consideration in the computation of the additional space charge on the object used for protection. The model of the electrical thundercloud is taken into consideration with all the electrical charge in it with its corresponding heights above ground. Plotted values are presented of the speed of the down-ward leader from the cloud versus the additional space charge, needed to be placed on the top of the object protected by direct lightning. Plotted values are also presented of different position of the horizontal distance of the protected object and its height versus the additional space charge. (Authors)

  9. Electric controlling of surface metal-insulator transition in the doped BaTiO3 film

    Directory of Open Access Journals (Sweden)

    Wei Xun

    2017-07-01

    Full Text Available Based on first-principles calculations, the BaTiO3(BTO film with local La-doping is studied. For a selected concentration and position of doping, the surface metal-insulator transition occurs under the applied electric field, and the domain appears near the surface for both bipolar states. Furthermore, for the insulated surface state, i.e., the downward polarization state in the doped film, the gradient bandgap structure is achieved, which favors the absorption of solar energy. Our investigation can provide an alternative avenue in modification of surface property and surface screening effect in polar materials.

  10. Onset and end of the summer melt season over sea ice: thermal structure and surface energy perspective from SHEBA

    Energy Technology Data Exchange (ETDEWEB)

    Persson, P.O.G. [University of Colorado, Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO (United States); National Oceanic and Atmospheric Administration/Earth Systems Research Laboratory, Physical Sciences Division (NOAA/ESRL/PSD), Boulder, CO (United States)

    2012-09-15

    Various measurements from the Surface Heat Flux of the Arctic Ocean (SHEBA) experiment have been combined to study structures and processes producing the onset and end of summer melt over Arctic sea ice. The analysis links the surface energy budget to free-troposphere synoptic variables, clouds, precipitation, and in-ice temperatures. The key results are (1) SHEBA melt-season transitions are associated with atmospheric synoptic events (2) onset of melt clearly occurs on May 28, while the end of melt is produced by a sequence of three atmospheric storm events over a 28-day period producing step-like reductions in the net surface energy flux. The last one occurs on August 22.; (3) melt onset is primarily due to large increases in the downwelling longwave radiation and modest decreases in the surface albedo; (4) decreases in the downwelling longwave radiation occur for all end-of-melt transition steps, while increases in surface albedo occur for the first two; (5) decreases in downwelling shortwave radiation contribute only to the first end-of-melt transition step; (6) springtime free-tropospheric warming preconditions the atmosphere-ice system for the subsequent melt onset; and (7) melt-season transitions also mark transitions in system responses to radiative energy flux changes because of invariant melt-season surface temperatures. The extensive SHEBA observations enable an understanding of the complex processes not available from other field program data. The analysis provides a basis for future testing of the generality of the results, and contributes to better physical understanding of multi-year analyses of melt-season trends from less extensive data sets. (orig.)

  11. Field measurement of albedo for limited extent test surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sailor, David J. [Portland State University, Department of Mechanical and Materials Engineering, P.O. Box 751-ME, Portland, OR 97207 (United States); Resh, Kyle; Segura, Del [Tulane University, Department of Mechanical Engineering, 400 Lindy Boggs Center, New Orleans, LA 70118 (United States)

    2006-05-15

    A new method is introduced for field measurement of surface albedo. This method consists of the use of a cylindrical shade ring made of opaque fabric with a known (low) albedo placed over a test surface. The albedo measurement is accomplished using two small pyranometers situated so that the downward-facing pyranometer receives radiation only from the test surface and the shade ring. The upward-facing pyranometer simultaneously records the incoming solar radiation. The radiation received by the downward-facing pyramometer is a combination of reflected radiation from shaded and unshaded portions of these two surfaces, requiring detailed accounting of the resulting view factor geometries. The method presented here improves upon past approaches by allowing for smaller sample sizes, minimizing errors associated with reflective properties of the surroundings, and allowing for accurate measurements even under partially cloudy skies. In addition to these methodological improvements we introduce an approach for estimating the uncertainty in the resulting albedo measurements. Results from field measurements are presented to validate the measurement protocol, and to compare its accuracy with the accuracy of a published standard. (author)

  12. Turbulent flow over an interactive alternating land-water surface

    Science.gov (United States)

    Van Heerwaarden, C.; Mellado, J. P.

    2014-12-01

    The alternating land-water surface is a challenging surface to represent accurately in weather and climate models, but it is of great importance for the surface energy balance in polar regions. The complexity of this surface lies in the fact that secondary circulations, which form at the boundary of water and land, interact strongly with the surface energy balance. Due to its large heat capacity, the water temperature adapts slowly to the flow, thus the properties of the atmosphere determine the uptake of energy from the water. In order to study this complex system in a simpler way, retaining only the most essential physics, we have simplified the full surface energy balance including radiation. We have derived a boundary condition that mimics the full balance and can be formulated as a so-called Robin boundary condition: a linear combination of Dirichlet (fixed temperature) and Neumann (fixed temperature gradient) ones. By spatially varying the coefficients, we are able to express land and water using this boundary condition. We have done a series of direct numerical simulations in which we generate artificial land-water patterns from noise created from a Gaussian spectrum centered around a dominant wave number. This method creates realistic random patterns, but we are still in control of the length scales. We show that the system can manifest itself in three regimes: micro-, meso- and macro-scale. In the micro-scale, we find perfect mixing of the near-surface atmosphere that results in identical air properties over water and land. In the meso-scale, secondary circulations alter the heat exchange considerably by advecting air between land and water. In addition, they bring the surface temperature of the land closer to that of the air, thereby modulating the energy loss due to outgoing longwave radiation. In the macro-scale regime, the flow over land and water become independent of each other and only the large scale forcings determine the energy balance.

  13. Mechanical Balance Laws for Boussinesq Models of Surface Water Waves

    Science.gov (United States)

    Ali, Alfatih; Kalisch, Henrik

    2012-06-01

    Depth-integrated long-wave models, such as the shallow-water and Boussinesq equations, are standard fare in the study of small amplitude surface waves in shallow water. While the shallow-water theory features conservation of mass, momentum and energy for smooth solutions, mechanical balance equations are not widely used in Boussinesq scaling, and it appears that the expressions for many of these quantities are not known. This work presents a systematic derivation of mass, momentum and energy densities and fluxes associated with a general family of Boussinesq systems. The derivation is based on a reconstruction of the velocity field and the pressure in the fluid column below the free surface, and the derivation of differential balance equations which are of the same asymptotic validity as the evolution equations. It is shown that all these mechanical quantities can be expressed in terms of the principal dependent variables of the Boussinesq system: the surface excursion η and the horizontal velocity w at a given level in the fluid.

  14. Atomic-scale friction on stepped surfaces of ionic crystals.

    Science.gov (United States)

    Steiner, Pascal; Gnecco, Enrico; Krok, Franciszek; Budzioch, Janusz; Walczak, Lukasz; Konior, Jerzy; Szymonski, Marek; Meyer, Ernst

    2011-05-06

    We report on high-resolution friction force microscopy on a stepped NaCl(001) surface in ultrahigh vacuum. The measurements were performed on single cleavage step edges. When blunt tips are used, friction is found to increase while scanning both up and down a step edge. With atomically sharp tips, friction still increases upwards, but it decreases and even changes sign downwards. Our observations extend previous results obtained without resolving atomic features and are associated with the competition between the Schwöbel barrier and the asymmetric potential well accompanying the step edges.

  15. Symmetric scaling properties in global surface air temperature anomalies

    Science.gov (United States)

    Varotsos, Costas A.; Efstathiou, Maria N.

    2015-08-01

    We have recently suggested "long-term memory" or internal long-range correlation within the time-series of land-surface air temperature (LSAT) anomalies in both hemispheres. For example, an increasing trend in the LSAT anomalies is followed by another one at a different time in a power-law fashion. However, our previous research was mainly focused on the overall long-term persistence, while in the present study, the upward and downward scaling dynamics of the LSAT anomalies are analysed, separately. Our results show that no significant fluctuation differences were found between the increments and decrements in LSAT anomalies, over the whole Earth and over each hemisphere, individually. On the contrary, the combination of land-surface air and sea-surface water temperature anomalies seemed to cause a departure from symmetry and the increments in the land and sea surface temperature anomalies appear to be more persistent than the decrements.

  16. A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Sedlar, Joseph; Tjernstroem, Michael; Leck, Caroline [Stockholm University, Department of Meteorology, Stockholm (Sweden); Mauritsen, Thorsten [Max-Planck-Institute for Meteorology, Hamburg (Germany); Shupe, Matthew D.; Persson, P.O.G. [University of Colorado, NOAA-ESRL-PSD, Boulder, CO (United States); Brooks, Ian M.; Birch, Cathryn E. [University of Leeds, School of Earth and Environment, Leeds (United Kingdom); Sirevaag, Anders [University of Bergen, Bjerknes Center for Climate Research, Bergen (Norway); Nicolaus, Marcel [Norwegian Polar Institute, Tromsoe (Norway); Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)

    2011-10-15

    Snow surface and sea-ice energy budgets were measured near 87.5 N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to -7 C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between -50 W m{sup -2} and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m{sup -2}, except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area. (orig.)

  17. Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface.

    Science.gov (United States)

    Zhang, Aizhong; Maki, Kara L; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Hindman, Holly B; Aquavella, James V; Zavislan, James M

    2015-03-01

    In this study, we explore the usage of ocular surface temperature (OST) decay patterns to distinguished between dry eye patients with aqueous deficient dry eye (ADDE) and meibomian gland dysfunction (MGD). The OST profiles of 20 dry eye subjects were measured by a long-wave infrared thermal camera in a standardized environment (24 °C, and relative humidity (RH) 40%). The subjects were instructed to blink every 5 s after 20 ∼ 25 min acclimation. Exponential decay curves were fit to the average temperature within a region of the central cornea. We find the MGD subjects have both a higher initial temperature (p model, referred to as the thermal impulse perturbation (TIP) model. We conclude that long-wave-infrared thermal imaging is a plausible tool in assisting with the classification of dry eye patient. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Low level chemiluminescence measurement of the binding of 8-methoxypsoralen to proteins and lymphocytic surfaces

    International Nuclear Information System (INIS)

    Lange, B.

    1980-01-01

    Photochemotherapy with 8-methoxypsoralen (8-MOP) and longwave ultraviolet light is beneficial in such different disorders like psoriasis, lichen planus, and mykosis fungoides. In contrast to a widely accepted hypothesis 8-MOP does not solely bind to nucleic acid, but also to certain proteins. The mechanism of this binding as well as the precise binding area are unknown. Therefore the UV-provoked reactions of 8-MOP with a lipid mixture, a glucosaminoglycan solution, a protein solution, and lymphocyte suspensions, respectively were investigated using low level chemiluminescence (LLCL). It was found an 8-MOP concentration-dependent decrease of LLCL intensity in the lymphocyte suspensions (10 3 to 10 4 cells/μl). This effect is result of the diminution of the photoactive 8-MOP content of the solution. 8-MOP binds quickly and in the course of a free radical reaction to lymphocytic surfaces and coincidentally loses its potency to start LLCL-detectable free radical chain responses. (author)

  19. Minimal surfaces

    CERN Document Server

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  20. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  1. Cycling downwards - dissolved organic matter in soils

    NARCIS (Netherlands)

    Kaiser, K.; Kalbitz, K.

    2012-01-01

    Dissolved organic matter has been recognized as mobile, thus crucial to translocation of metals, pollutants but also of nutrients in soil. We present a conceptual model of the vertical movement of dissolved organic matter with soil water, which deviates from the view of a chromatographic stripping

  2. Comparative Study of the Spherical Downward Continuation

    Czech Academy of Sciences Publication Activity Database

    Sebera, Josef; Pitoňák, M.; Hamáčková, E.; Novák, P.

    2015-01-01

    Roč. 36, č. 2 (2015), s. 253-267 ISSN 0169-3298 Grant - others:GA MŠk(CZ) CZ.1.05/1.1.00/02.0090 Institutional support: RVO:67985815 Keywords : limited airborne gravity * potential-field data * horizontal plane Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 3.622, year: 2015

  3. Sustainable development: downwards and upwards strategies

    International Nuclear Information System (INIS)

    Claval, Paul

    2006-01-01

    The idea of sustainable development, which was officialised by the Brundtland Report in 1987, was born from the will to reconcile the defence of ecological equilibria with the necessity to offer better conditions of life to the developing countries. It was supported from the start by the most important ecological NGOs. Following Solow, economists showed that, under specific conditions, economic growth was not conducive to environmental degradation. In 1992, the Rio de Janeiro Conference transformed sustainable growth into a political obligation for political authorities, whatever their scale. Because of the urgency created by climatic change, targets were fixed at the top level, and then applied to every State. Other procedures, which give more initiative to the local and national levels, are also used

  4. Process Parameter Identification in Thin Film Flows Driven by a Stretching Surface

    Directory of Open Access Journals (Sweden)

    Satyananda Panda

    2014-01-01

    Full Text Available The flow of a thin liquid film over a heated stretching surface is considered in this study. Due to a potential nonuniform temperature distribution on the stretching sheet, a temperature gradient occurs in the fluid which produces surface tension gradient at the free surface of the thin film. As a result, the free surface deforms and these deformations are advected by the flow in the stretching direction. This work focuses on the inverse problem of reconstructing the sheet temperature distribution and the sheet stretch rate from observed free surface variations. This work builds on the analysis of Santra and Dandapat (2009 who, based on the long-wave expansion of the Navier-Stokes equations, formulate a partial differential equation which describes the evolution of the thickness of a film over a nonisothermal stretched surface. In this work, we show that after algebraic manipulation of a discrete form of the governing equations, it is possible to reconstruct either the unknown temperature field on the sheet and hence the resulting heat transfer or the stretching rate of the underlying surface. We illustrate the proposed methodology and test its applicability on a range of test problems.

  5. Development of an Urban Multilayer Radiation Scheme and Its Application to the Urban Surface Warming Potential

    Science.gov (United States)

    Aoyagi, Toshinori; Takahashi, Shunji

    2012-02-01

    To investigate how a three-dimensional structure such as an urban canyon can affect urban surface warming, we developed an urban multilayer radiation scheme. The complete consideration of multiple scattering of shortwave and longwave radiation using the radiosity method is an important feature of the present scheme. A brief description of this scheme is presented, followed by evaluations that compare its results with observations of the effective albedo and radiative temperature for urban blocks. Next, we calculate the urban surface warming potential (USWP), defined as the difference between the daily mean radiative temperature of urban surfaces (which are assumed to be black bodies), including their canyon effects and the daily mean temperature of a flat surface with the same material properties, under a radiative equilibrium state. Assuming standard material properties (albedo and emissivity of 0.4 and 0.9, respectively), we studied the sensitivity of the USWP to various aspect ratios of building heights to road widths. The results show that the temporally-averaged surface temperature of an urban area can be higher than that of a flat surface. In addition, we determined the overestimation of the effective temperature of urban surfaces induced by the overestimation of the radiation distribution to the walls when one uses a single-layer scheme for urban block arrays that have a low sky-view factor less than around 0.5.

  6. Analysis of energy flow during playground surface impacts.

    Science.gov (United States)

    Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

    2013-10-01

    The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

  7. Rumble surfaces

    CSIR Research Space (South Africa)

    National Institute for Transport and Road

    1977-01-01

    Full Text Available Rumble surfaces are intermittent short lengths of coarse-textured road surfacings on which vehicle tyres produce a rumbling sound. used in conjunction with appropriate roadsigns and markings, they can reduce accidents on rural roads by alerting...

  8. Constraining the Surface Energy Balance of Snow in Complex Terrain

    Science.gov (United States)

    Lapo, Karl E.

    values and coupled land-atmosphere models have difficulty representing these processes. We developed a new method analyzing turbulent fluxes at the land surface that relies on using the observed surface temperature, which we called the offline turbulence method. We used this method to test a number of stability schemes as they are implemented within land models. Stability schemes can cause small biases in the simulated sensible heat flux, but these are caused by compensating errors, as no single method was able to accurately reproduce the observed distribution of the sensible heat flux. We described how these turbulence schemes perform within different turbulence regimes, particularly noting the difficulty representing turbulence during conditions with faster wind speeds and the transition between weak and strong wind turbulence regimes. Heterogeneity in the horizontal distribution of surface temperature associated with different land surface types likely explains some of the missing physics within land models and is manifested as counter-gradient fluxes in observations. The coupling of land and atmospheric models needs further attention, as we highlight processes that are missing. Expanding on the utility of surface temperature, Ts, in model evaluations, we demonstrated the utility of using surface temperature in snow models evaluations. Ts is the diagnostic variable of the modeled surface energy balance within physically-based models and is an ideal supplement to traditional evaluation techniques. We demonstrated how modeling decisions affect Ts, specifically testing the impact of vertical layer structure, thermal conductivity, and stability corrections in addition to the effect of uncertainty in forcing data on simulated Ts. The internal modeling decisions had minimal impacts relative to uncertainty in the forcing data. Uncertainty in downwelling longwave was found to have the largest impact on simulated Ts. Using Ts, we demonstrated how various errors in the forcing

  9. Surface thermodynamics

    International Nuclear Information System (INIS)

    Garcia-Moliner, F.

    1975-01-01

    Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

  10. Intraseasonal sea surface temperature variability in Indonesian seas

    Science.gov (United States)

    Napitu, A. M.; Gordon, A. L.; Yuan, X.

    2012-12-01

    The satellite-derived sea surface temperature (SST) data, 1998-mid 2012, are used to examine intraseasonal variability (ISV; 20-90 days) across the Indonesian seas. The most energetic ISV is observed in the Banda Sea and across the Indo-Australia basin with an The satellite-derived sea surface temperature (SST) data, 1998-mid 2012, are used to examine intraseasonal variability (ISV; 20-90 days) across the Indonesian seas. The most energetic ISV is observed in the Banda Sea and across the Indo-Australia basin with an average SST standard deviation (STD) between 0.4-0.5°C, with strongest signature during boreal winter. What physical processes force the SST ISV variability within the Indonesian seas? Ocean process, sea-air interaction, or both? To help identify the main forcing, the satellite derived outgoing longwave radiation (OLR) and wind stress data in the region are examined. The OLR shows robust intraseasonal variations and is significantly correlated with the SST, particularly for variability with periods of 30-60 days, with OLR accounting for ~60-70% of the SST variance. The OLR is also maximum during boreal winter. Conversely, the surface wind may play insignificant role in perturbing the SST at intraseasonal timescales as shown by weak correlation between wind stress and SST. We thus suspect that the surface solar flux (suggested by the OLR) is likely more dominant than the surface turbulent heat flux (indicated by the surface wind) as the main source for the ISV in the SST in Indonesian seas. Furthermore the maximum OLR phase, coupled with a period of minimum mixed layer depth, may explain the strong SST variation during boreal winter in Indonesian seas. The influence of the Madden-Julian Oscillation (MJO) on the OLR and SST variability is currently being evaluated.

  11. Investigation of empirical correlations on the determination of condensation heat transfer characteristics during downward annular flow of R134a inside a vertical smooth tube using artificial intelligence algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Balcilar, Muhammet; Dalkilic, Ahmet Selim; Bolat, Berna [Yildiz Technical University, Istanbul (Turkmenistan); Wongwises, Somchai [King Mongkut' s University of Technology Thonburi, Bangkok (Thailand)

    2011-10-15

    The heat transfer characteristics of R134a during downward condensation are investigated experimentally and numerically. While the convective heat transfer coefficient, two-phase multiplier and frictional pressure drop are considered to be the significant variables as output for the analysis, inputs of the computational numerical techniques include the important two-phase flow parameters such as equivalent Reynolds number, Prandtl number, Bond number, Froude number, Lockhart and Martinelli number. Genetic algorithm technique (GA), unconstrained nonlinear minimization algorithm-Nelder-Mead method (NM) and non-linear least squares error method (NLS) are applied for the optimization of these significant variables in this study. Regression analysis gave convincing correlations on the prediction of condensation heat transfer characteristics using {+-}30% deviation band for practical applications. The most suitable coefficients of the proposed correlations are depicted to be compatible with the large number of experimental data by means of the computational numerical methods. Validation process of the proposed correlations is accomplished by means of the comparison between the various correlations reported in the literature.

  12. Simulated Effects of Land Cover Conversion on the Surface Energy Budget in the Southwest of China

    Directory of Open Access Journals (Sweden)

    Jiangbo Gao

    2014-03-01

    Full Text Available In this paper, the coupled WRF/SSiB model, accompanied by a Karst Rocky Desertification (KRD map of the Guizhou Karst Plateau (GKP of China, was applied to detect how the changed vegetation and soil characteristics over the GKP modify the energy balance at the land surface. The results indicated that land degradation led to reduced net radiation by inducing more upward shortwave and longwave radiation, which were associated with increasing surface albedo and temperature, respectively. The KRD also resulted in changed surface energy partitioning into sensible and latent heat fluxes. The latent heat flux at land surface was reduced substantially due to the higher surface albedo and stomatal resistance, the lower Leaf Area Index (LAI and roughness length in the degradation experiment, while the sensible heat flux increased, mainly because of the higher surface temperature. Furthermore, the moisture flux convergence was reduced, owing to the lower atmospheric heating and the relative subsidence. However, compared with the reduced evaporation, the decrease in moisture flux convergence contributed much less to the reduced precipitation. Precipitation strongly affects soil moisture, vegetation growth and phenology, and thus evaporation and convective latent heating, so when precipitation was changed, a feedback loop was created.

  13. Defining the Magnitude: Patterns, Regularities and Direct TOA-Surface Flux Relationships in the 15-Year Long CERES Satellite Data — Observations, Model and Theory

    Science.gov (United States)

    Zagoni, M.

    2017-12-01

    Over the past fifteen years, the NASA Clouds and the Earth's Radiant Energy System (CERES) satellite mission has provided the scientific community with the most reliable Earth radiation budget data. This presentation offers quantitative assessment of the published CERES Energy Balanced and Filled (EBAF) Edition 2.8 and Edition 4.0 data products, and reveals several internal patterns, ratios and regularities within the annual global mean flux components of the all-sky and clear-sky surface and atmospheric energy budgets. The found patterns, among others, include: (i) direct relationships between the top-of-atmosphere (TOA) radiative and surface radiative and non-radiative fluxes (contradicting the expectation that TOA and surface fluxes are physically decoupled); (ii) integer ratios and relationships between the absorbed and emitted surface and atmospheric energy flow elements; and (iii) definite connections among the clear-sky and the all-sky shortwave, longwave and non-radiative (turbulent) flux elements and the corresponding greenhouse effect. Comparison between the EBAF Ed2.8 and Ed4.0 SFC and TOA data products and trend analyses of the normalized clear-sky and all-sky greenhouse factors are presented. Longwave cloud radiative effect (LW CRE) proved to be playing a principal role in organizing the found numerical patterns in the surface and atmospheric energy flow components. All of the revealed structures are quantitatively valid within the one-sigma range of uncertainty of the involved individual flux elements. This presentation offers a conceptual framework to interpret the found relationships and shows how the observed CERES fluxes can be deduced from this proposed physical model. An important conclusion drawn from our analysis is that the internal atmospheric and surface energy flow system forms a definite structure and seems to be more constrained to the incoming solar energy than previously thought.

  14. The effect of surface anisotropy in the slippery zone of Nepenthes alata pitchers on beetle attachment

    Directory of Open Access Journals (Sweden)

    Elena V. Gorb

    2011-06-01

    Full Text Available The slippery zone in pitchers of the carnivorous plant Nepenthes alata bears scattered prominent lunate cells and displays continuous epicuticular crystalline wax coverage. The aim of this study was to examine the influence of the surface anisotropy, caused by the shape of lunate cells, on insect attachment ability. Traction tests with ladybird beetles Coccinella septempunctata were performed in two types of experiments, where surface samples of (1 intact pitchers, (2 chemically de-waxed pitchers, and (3 their polymer replicas were placed horizontally. Beetle traction forces were measured when they walked on test surfaces in either an upward (towards the peristome or downward (towards the pitcher bottom direction, corresponding to the upright or inverted positions of the pitcher. On intact pitcher surfaces covered with both lunate cells and wax crystals, experiments showed significantly higher forces in the direction towards the pitcher bottom. To distinguish between the contributions, from claw interlocking and pad adhesion, to insect attachment on the pitcher surfaces, intact versus claw-ablated beetles were used in the second type of experiment. On both de-waxed plant samples and their replicas, intact insects generated much higher forces in the downward direction compared to the upward one, whereas clawless insects did not. These results led to the conclusion that, (i due to the particular shape of lunate cells, the pitcher surface has anisotropic properties in terms of insect attachment, and (ii claws were mainly responsible for attachment enhancement in the downward pitcher direction, since, in this direction, they could interlock with overhanging edges of lunate cells.

  15. a Research on Monitoring Surface Deformation and Relationships with Surface Parameters in Qinghai Tibetan Plateau Permafrost

    Science.gov (United States)

    Mi, S. J.; Li, Y. T.; Wang, F.; Li, L.; Ge, Y.; Luo, L.; Zhang, C. L.; Chen, J. B.

    2017-09-01

    different in arid areas and wet areas. During the research time, frost heaving firstly accounted for a large proportion both in the arid and wet areas with the decrease of downward radiation from July to December; after December, thaw settlement came into prominence with the increase downward radiation in the arid areas, while in the wet areas, surface put into diverse situations because of water transformation leading to severe deformation. In summary, soil moisture is an important factor that influences the surface deformation. This relationship between deformation process and soil moisture will be researched more in our further work.

  16. Evaluation of Arctic broadband surface radiation measurements

    Directory of Open Access Journals (Sweden)

    N. Matsui

    2012-02-01

    Full Text Available The Arctic is a challenging environment for making in-situ surface radiation measurements. A standard suite of radiation sensors is typically designed to measure incoming and outgoing shortwave (SW and thermal infrared, or longwave (LW, radiation. Enhancements may include various sensors for measuring irradiance in narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers that keep sensors and shading devices trained on the sun along its diurnal path. High quality measurements require striking a balance between locating stations in a pristine undisturbed setting free of artificial blockage (such as from buildings and towers and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data in the Arctic include solar tracker malfunctions, rime/frost/snow deposition on the protective glass domes of the radiometers and operational problems due to limited operator access in extreme weather conditions. In this study, comparisons are made between the global and component sum (direct [vertical component] + diffuse SW measurements. The difference between these two quantities (that theoretically should be zero is used to illustrate the magnitude and seasonality of arctic radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both SW and LW measurements. Solutions to these operational problems that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols are proposed.

  17. ENSO surface shortwave radiation forcing over the tropical Pacific

    Directory of Open Access Journals (Sweden)

    K. G. Pavlakis

    2008-09-01

    Full Text Available We have studied the spatial and temporal variation of the downward shortwave radiation (DSR at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40° S–40° N, 90° E–75° W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters, and aerosol parameters from GADS (acronyms explained in main text. A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A time-series, in the region 7° S–5° N 160° E–160° W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm−2 during El Niño episodes to +40 Wm−2 during La Niña events. Within the Niño-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10° S–5° N, 120–140° E, where the mean DSR anomaly values range from +20 Wm−2 to −20 Wm−2 during El Niño and La Niña episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7–15° N 150–170° E, precedes the Niño-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Niño or La Niña conditions prevail.

  18. Redatuming borehole-to-surface electromagnetic data using Stratton-Chu integral transforms

    DEFF Research Database (Denmark)

    Zhdanov, Michael; Cai, Hongzhu

    2012-01-01

    We present a new method of analyzing borehole-to-surface electromagnetic (BSEM) survey data based on redatuming of the observed data from receivers distributed over the surface of the earth onto virtual receivers located within the subsurface. The virtual receivers can be placed close to the target...... of interest, such as just above a hydrocarbon reservoir, which increases the sensitivity of the EM data to the target. The method is based on the principles of downward analytical continuation of EM fields. We use Stratton-Chu type integral transforms to calculate the EM fields at the virtual receivers. Model...

  19. The Plumbing of Land Surface Models: Is Poor Performance a Result of Methodology or Data Quality?

    Science.gov (United States)

    Haughton, Ned; Abramowitz, Gab; Pitman, Andy J.; Or, Dani; Best, Martin J.; Johnson, Helen R.; Balsamo, Gianpaolo; Boone, Aaron; Cuntz, Matthais; Decharme, Bertrand; hide

    2016-01-01

    The PALS Land sUrface Model Benchmarking Evaluation pRoject (PLUMBER) illustrated the value of prescribing a priori performance targets in model intercomparisons. It showed that the performance of turbulent energy flux predictions from different land surface models, at a broad range of flux tower sites using common evaluation metrics, was on average worse than relatively simple empirical models. For sensible heat fluxes, all land surface models were outperformed by a linear regression against downward shortwave radiation. For latent heat flux, all land surface models were outperformed by a regression against downward shortwave, surface air temperature and relative humidity. These results are explored here in greater detail and possible causes are investigated. We examine whether particular metrics or sites unduly influence the collated results, whether results change according to time-scale aggregation and whether a lack of energy conservation in fluxtower data gives the empirical models an unfair advantage in the intercomparison. We demonstrate that energy conservation in the observational data is not responsible for these results. We also show that the partitioning between sensible and latent heat fluxes in LSMs, rather than the calculation of available energy, is the cause of the original findings. Finally, we present evidence suggesting that the nature of this partitioning problem is likely shared among all contributing LSMs. While we do not find a single candidate explanation forwhy land surface models perform poorly relative to empirical benchmarks in PLUMBER, we do exclude multiple possible explanations and provide guidance on where future research should focus.

  20. Surface radiation fluxes in transient climate simulations

    Science.gov (United States)

    Garratt, J. R.; O'Brien, D. M.; Dix, M. R.; Murphy, J. M.; Stephens, G. L.; Wild, M.

    1999-01-01

    Transient CO 2 experiments from five coupled climate models, in which the CO 2 concentration increases at rates of 0.6-1.1% per annum for periods of 75-200 years, are used to document the responses of surface radiation fluxes, and associated atmospheric properties, to the CO 2 increase. In all five models, the responses of global surface temperature and column water vapour are non-linear and fairly tightly constrained. Thus, global warming lies between 1.9 and 2.7 K at doubled, and between 3.1 and 4.1 K at tripled, CO 2, whilst column water vapour increases by between 3.5 and 4.5 mm at doubled, and between 7 and 8 mm at tripled, CO 2. Global cloud fraction tends to decrease by 1-2% out to tripled CO 2, mainly the result of decreases in low cloud. Global increases in column water, and differences in these increases between models, are mainly determined by the warming of the tropical oceans relative to the middle and high latitudes; these links are emphasised in the zonal profiles of warming and column water vapour increase, with strong water vapour maxima in the tropics. In all models the all-sky shortwave flux to the surface S↓ (global, annual average) changes by less than 5 W m -2 out to tripled CO 2, in some cases being essentially invariant in time. In contrast, the longwave flux to the surface L↓ increases significantly, by 25 W m -2 typically at tripled CO 2. The variations of S↓ and L↓ (clear-sky and all-sky fluxes) with increase in CO 2 concentration are generally non-linear, reflecting the effects of ocean thermal inertia, but as functions of global warming are close to linear in all five models. This is best illustrated for the clear-sky downwelling fluxes, and the net radiation. Regionally, as illustrated in zonal profiles and global distributions, greatest changes in both S↓ and L↓ are the result primarily of local maxima in warming and column water vapour increases.

  1. Surface mining

    Science.gov (United States)

    Robert Leopold; Bruce Rowland; Reed Stalder

    1979-01-01

    The surface mining process consists of four phases: (1) exploration; (2) development; (3) production; and (4) reclamation. A variety of surface mining methods has been developed, including strip mining, auger, area strip, open pit, dredging, and hydraulic. Sound planning and design techniques are essential to implement alternatives to meet the myriad of laws,...

  2. Superhydrophobic surfaces

    Science.gov (United States)

    Wang, Evelyn N; McCarthy, Matthew; Enright, Ryan; Culver, James N; Gerasopoulos, Konstantinos; Ghodssi, Reza

    2015-03-24

    Surfaces having a hierarchical structure--having features of both microscale and nanoscale dimensions--can exhibit superhydrophobic properties and advantageous condensation and heat transfer properties. The hierarchical surfaces can be fabricated using biological nanostructures, such as viruses as a self-assembled nanoscale template.

  3. Surface characterization

    Science.gov (United States)

    Mandla A. Tshabalala

    2005-01-01

    Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites, as the...

  4. The intraseasonal variability of winter semester surface air temperature in Antarctica

    Directory of Open Access Journals (Sweden)

    Lejiang Yu

    2011-02-01

    Full Text Available This study investigates systematically the intraseasonal variability of surface air temperature over Antarctica by applying empirical orthogonal function (EOF analysis to the National Centers for Environmental Prediction, US Department of Energy, Reanalysis 2 data set for the period of 1979 through 2007. The results reveal the existence of two major intraseasonal oscillations of surface temperature with periods of 26–30 days and 14 days during the Antarctic winter season in the region south of 60°S. The first EOF mode shows a nearly uniform spatial pattern in Antarctica and the Southern Ocean associated with the Antarctic Oscillation. The mode-1 intraseasonal variability of the surface temperature leads that of upper atmosphere by one day with the largest correlation at 300-hPa level geopotential heights. The intraseasonal variability of the mode-1 EOF is closely related to the variations of surface net longwave radiation the total cloud cover over Antarctica. The other major EOF modes reveal the existence of eastward propagating phases over the Southern Ocean and marginal region in Antarctica. The leading two propagating modes respond to Pacific–South American modes. Meridional winds induced by the wave train from the tropics have a direct influence on the surface air temperature over the Southern Ocean and the marginal region of the Antarctic continent.

  5. A Climatology of Surface Cloud Radiative Effects at the ARM Tropical Western Pacific Sites

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Long, Charles N.; Flaherty, Julia E.

    2013-04-01

    Cloud radiative effects on surface downwelling fluxes are investigated using long-term datasets from the three Atmospheric Radiation Measurement (ARM) sites in the Tropical Western Pacific (TWP) region. The Nauru and Darwin sites show significant variability in sky cover, downwelling radiative fluxes, and surface cloud radiative effect (CRE) due to El Niño and the Australian monsoon, respectively, while the Manus site shows little intra-seasonal or interannual variability. Cloud radar measurement of cloud base and top heights are used to define cloud types so that the effect of cloud type on the surface CRE can be examined. Clouds with low bases contribute 71-75% of the surface shortwave (SW) CRE and 66-74% of the surface longwave (LW) CRE at the three TWP sites, while clouds with mid-level bases contribute 8-9% of the SW CRE and 12-14% of the LW CRE, and clouds with high bases contribute 16-19% of the SW CRE and 15-21% of the LW CRE.

  6. Two-dimensional interaction of a shear flow with a free surface in a stratified fluid and its solitary-wave solutions via mathematical methods

    Science.gov (United States)

    Seadawy, Aly R.

    2017-12-01

    In this study, we presented the problem formulations of models for internal solitary waves in a stratified shear flow with a free surface. The nonlinear higher order of extended KdV equations for the free surface displacement is generated. We derived the coefficients of the nonlinear higher-order extended KdV equation in terms of integrals of the modal function for the linear long-wave theory. The wave amplitude potential and the fluid pressure of the extended KdV equation in the form of solitary-wave solutions are deduced. We discussed and analyzed the stability of the obtained solutions and the movement role of the waves by making graphs of the exact solutions.

  7. Multimodal imaging of ocular surface of dry eye subjects

    Science.gov (United States)

    Zhang, Aizhong; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Aquavella, James V.; Zavislan, James M.

    2016-03-01

    To study the relationship between the corneal lipid layer and the ocular surface temperature (OST), we conducted a clinical trial for 20 subjects. Subjects were clinically screened prior to the trial. Of the 20 subjects, 15 have Meibomian gland dysfunction (MGD), and 5 have aqueous-deficient dry eye (ADDE). A custom, circularly polarized illumination video tearscope measured the lipid layer thickness of the ocular tear film. A long-wave infrared video camera recorded the dynamic thermal properties of the ocular team film. The results of these two methods were analyzed and compared. Using principal component analysis (PCA) of the lipid layer distribution, we find that the 20 subjects could be categorized into five statistically significant groups, independent of their original clinical classification: thin (6 subjects), medium (5 subjects), medium and homogenous (3 subjects), thick (4 subjects), and very thick (2 subjects) lipids, respectively. We also conducted PCA of the OST data, and recategorized the subjects into two thermal groups by k-means clustering: one includes all ADDE subjects and some MGD subjects; the other includes the remaining MGD subjects. By comparing these two methods, we find that dry eye subjects with thin ( 40 nm), there is no strong correlation between the lipid layer thickness and heterogeneity and the OST patterns.

  8. Seasonal Surface Spectral Emissivity Derived from Terra MODIS Data

    Science.gov (United States)

    Sun-Mack, Sunny; Chen, Yan; Minnis, Patrick; Young, DavidF.; Smith, William J., Jr.

    2004-01-01

    The CERES (Clouds and the Earth's Radiant Energy System) Project is measuring broadband shortwave and longwave radiances and deriving cloud properties form various images to produce a combined global radiation and cloud property data set. In this paper, simultaneous data from Terra MODIS (Moderate Resolution Imaging Spectroradiometer) taken at 3.7, 8.5, 11.0, and 12.0 m are used to derive the skin temperature and the surface emissivities at the same wavelengths. The methodology uses separate measurements of clear sky temperature in each channel determined by scene classification during the daytime and at night. The relationships between the various channels at night are used during the day when solar reflectance affects the 3.7- m radiances. A set of simultaneous equations is then solved to derive the emissivities. Global monthly emissivity maps are derived from Terra MODIS data while numerical weather analyses provide soundings for correcting the observed radiances for atmospheric absorption. These maps are used by CERES and other cloud retrieval algorithms.

  9. Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

    Science.gov (United States)

    Giblin, Jay P.; Dixon, John; Dupuis, Julia R.; Cosofret, Bogdan R.; Marinelli, William J.

    2017-05-01

    Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army. In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system's cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface.

  10. Convex surfaces

    CERN Document Server

    Busemann, Herbert

    2008-01-01

    This exploration of convex surfaces focuses on extrinsic geometry and applications of the Brunn-Minkowski theory. It also examines intrinsic geometry and the realization of intrinsic metrics. 1958 edition.

  11. Surface boxplots

    KAUST Repository

    Genton, Marc G.

    2014-01-22

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  12. Surface boxplots

    KAUST Repository

    Genton, Marc G.; Johnson, Christopher; Potter, Kristin; Stenchikov, Georgiy L.; Sun, Ying

    2014-01-01

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  13. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  14. Downscaling Satellite Land Surface Temperatures in Urban Regions for Surface Energy Balance Study and Heat Index Development

    Science.gov (United States)

    Norouzi, H.; Bah, A.; Prakash, S.; Nouri, N.; Blake, R.

    2017-12-01

    A great percentage of the world's population reside in urban areas that are exposed to the threats of global and regional climate changes and associated extreme weather events. Among them, urban heat islands have significant health and economic impacts due to higher thermal gradients of impermeable surfaces in urban regions compared to their surrounding rural areas. Therefore, accurate characterization of the surface energy balance in urban regions are required to predict these extreme events. High spatial resolution Land surface temperature (LST) in the scale of street level in the cities can provide wealth of information to study surface energy balance and eventually providing a reliable heat index. In this study, we estimate high-resolution LST maps using combination of LandSat 8 and infrared based satellite products such as Moderate Resolution Imaging Spectroradiometer (MODIS) and newly launched Geostationary Operational Environmental Satellite-R Series (GOES-R). Landsat 8 provides higher spatial resolution (30 m) estimates of skin temperature every 16 days. However, MODIS and GOES-R have lower spatial resolution (1km and 4km respectively) with much higher temporal resolution. Several statistical downscaling methods were investigated to provide high spatiotemporal LST maps in urban regions. The results reveal that statistical methods such as Principal Component Analysis (PCA) can provide reliable estimations of LST downscaling with 2K accuracy. Other methods also were tried including aggregating (up-scaling) the high-resolution data to a coarse one to examine the limitations and to build the model. Additionally, we deployed flux towers over distinct materials such as concrete, asphalt, and rooftops in New York City to monitor the sensible and latent heat fluxes through eddy covariance method. To account for the incoming and outgoing radiation, a 4-component radiometer is used that can observe both incoming and outgoing longwave and shortwave radiation. This

  15. Martian surface

    International Nuclear Information System (INIS)

    Carr, M.H.

    1987-01-01

    The surface of Mars is characterized on the basis of reformatted Viking remote-sensing data, summarizing results published during the period 1983-1986. Topics examined include impact craters, ridges and faults, volcanic studies (modeling of surface effects on volcanic activity, description and interpretation of volcanic features, and calculations on lava-ice interactions), the role of liquid water on Mars, evidence for abundant ground ice at high latitudes, water-cycle modeling, and the composition and dynamics of Martian dust

  16. Surface decontamination

    International Nuclear Information System (INIS)

    Silva, S. da; Teixeira, M.V.

    1986-06-01

    The general methods of surface decontamination used in laboratory and others nuclear installations areas, as well as the procedures for handling radioactive materials and surfaces of work are presented. Some methods for decontamination of body external parts are mentioned. The medical supervision and assistance are required for internal or external contamination involving or not lesion in persons. From this medical radiation protection decontamination procedures are determined. (M.C.K.) [pt

  17. Surface phonons

    CERN Document Server

    Wette, Frederik

    1991-01-01

    In recent years substantial progress has been made in the detection of surface phonons owing to considerable improvements in inelastic rare gas scattering tech­ niques and electron energy loss spectroscopy. With these methods it has become possible to measure surface vibrations in a wide energy range for all wave vectors in the two-dimensional Brillouin zone and thus to deduce the complete surface phonon dispersion curves. Inelastic atomic beam scattering and electron energy loss spectroscopy have started to play a role in the study of surface phonons similar to the one played by inelastic neutron scattering in the investigation of bulk phonons in the last thirty years. Detailed comparison between experimen­ tal results and theoretical studies of inelastic surface scattering and of surface phonons has now become feasible. It is therefore possible to test and to improve the details of interaction models which have been worked out theoretically in the last few decades. At this point we felt that a concise, co...

  18. An energy balance model exploration of the impacts of interactions between surface albedo, cloud cover and water vapor on polar amplification

    Science.gov (United States)

    Södergren, A. Helena; McDonald, Adrian J.; Bodeker, Gregory E.

    2017-11-01

    We examine the effects of non-linear interactions between surface albedo, water vapor and cloud cover (referred to as climate variables) on amplified warming of the polar regions, using a new energy balance model. Our simulations show that the sum of the contributions to surface temperature changes due to any variable considered in isolation is smaller than the temperature changes from coupled feedback simulations. This non-linearity is strongest when all three climate variables are allowed to interact. Surface albedo appears to be the strongest driver of this non-linear behavior, followed by water vapor and clouds. This is because increases in longwave radiation absorbed by the surface, related to increases in water vapor and clouds, and increases in surface absorbed shortwave radiation caused by a decrease in surface albedo, amplify each other. Furthermore, our results corroborate previous findings that while increases in cloud cover and water vapor, along with the greenhouse effect itself, warm the polar regions, water vapor also significantly warms equatorial regions, which reduces polar amplification. Changes in surface albedo drive large changes in absorption of incoming shortwave radiation, thereby enhancing surface warming. Unlike high latitudes, surface albedo change at low latitudes are more constrained. Interactions between surface albedo, water vapor and clouds drive larger increases in temperatures in the polar regions compared to low latitudes. This is in spite of the fact that, due to a forcing, cloud cover increases at high latitudes and decreases in low latitudes, and that water vapor significantly enhances warming at low latitudes.

  19. A physically based model of global freshwater surface temperature

    Science.gov (United States)

    van Beek, Ludovicus P. H.; Eikelboom, Tessa; van Vliet, Michelle T. H.; Bierkens, Marc F. P.

    2012-09-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for

  20. Characteristics of Eurasian snowmelt and its impacts on the land surface and surface climate

    Science.gov (United States)

    Ye, Kunhui; Lau, Ngar-Cheung

    2018-03-01

    The local hydrological and climatic impacts of Eurasian snowmelt are studied using advanced land surface and atmospheric data. It is found that intense melting of snow is located at mid-high latitudes in April and May. Snowmelt plays an important role in determining the seasonal cycles of surface runoff and soil moisture (SM). Specifically, melting is accompanied by sharp responses in surface runoff and surface SM while the impacts are delayed for deeper-layer of soil. This is particularly significant in the western sector of Eurasia. On interannual timescales, the responses of various surface parameters to snowmelt in the same month are rather significant. However, the persistence of surface SM anomalies is weak due to the strong soil evaporation anomalies and surplus of surface energy for evaporation. Strong impacts on the sensible heat flux, planetary boundary layer height and precipitation in the next month following the melting of snow are identified in west Russia and Siberia. Downward propagation of surface SM anomalies is observed and a positive evaporation-convection feedback is identified in west Russia. However, the subsequent impacts on the local convective precipitation in late spring-summer and its contribution to the total precipitation are seemingly weak. The atmospheric water vapor convergence has strong control over the total precipitation anomalies. Overall, snowmelt-produced SM anomalies are not found to significantly impact the late spring-summer local climate anomalies in Northern Eurasia. Therefore, the delayed remote-responses of atmospheric circulation and climate to the melting of Eurasian snow may be only possible near the melting period.

  1. CFD simulation of simultaneous monotonic cooling and surface heat transfer coefficient

    International Nuclear Information System (INIS)

    Mihálka, Peter; Matiašovský, Peter

    2016-01-01

    The monotonic heating regime method for determination of thermal diffusivity is based on the analysis of an unsteady-state (stabilised) thermal process characterised by an independence of the space-time temperature distribution on initial conditions. At the first kind of the monotonic regime a sample of simple geometry is heated / cooled at constant ambient temperature. The determination of thermal diffusivity requires the determination rate of a temperature change and simultaneous determination of the first eigenvalue. According to a characteristic equation the first eigenvalue is a function of the Biot number defined by a surface heat transfer coefficient and thermal conductivity of an analysed material. Knowing the surface heat transfer coefficient and the first eigenvalue the thermal conductivity can be determined. The surface heat transport coefficient during the monotonic regime can be determined by the continuous measurement of long-wave radiation heat flow and the photoelectric measurement of the air refractive index gradient in a boundary layer. CFD simulation of the cooling process was carried out to analyse local convective and radiative heat transfer coefficients more in detail. Influence of ambient air flow was analysed. The obtained eigenvalues and corresponding surface heat transfer coefficient values enable to determine thermal conductivity of the analysed specimen together with its thermal diffusivity during a monotonic heating regime.

  2. Impact of soil moisture and winter wheat height from the Loess Plateau in Northwest China on surface spectral albedo

    Science.gov (United States)

    Li, Zhenchao; Yang, Jiaxi; Gao, Xiaoqing; Zheng, Zhiyuan; Yu, Ye; Hou, Xuhong; Wei, Zhigang

    2018-02-01

    The understanding of surface spectral radiation and reflected radiation characteristics of different surfaces in different climate zones aids in the interpretation of regional surface energy transfers and the development of land surface models. This study analysed surface spectral radiation variations and corresponding surface albedo characteristics at different wavelengths as well as the relationship between 5-cm soil moisture and surface albedo on typical sunny days during the winter wheat growth period. The analysis was conducted using observational Loess Plateau winter wheat data from 2015. The results show that the ratio of atmospheric downward radiation to global radiation on typical sunny days is highest for near-infrared wavelengths, followed by visible wavelengths and ultraviolet wavelengths, with values of 57.3, 38.7 and 4.0%, respectively. The ratio of reflected spectral radiation to global radiation varies based on land surface type. The visible radiation reflected by vegetated surfaces is far less than that reflected by bare ground, with surface albedos of 0.045 and 0.27, respectively. Thus, vegetated surfaces absorb more visible radiation than bare ground. The atmospheric downward spectral radiation to global radiation diurnal variation ratios vary for near-infrared wavelengths versus visible and ultraviolet wavelengths on typical sunny days. The near-infrared wavelengths ratio is higher in the morning and evening and lower at noon. The visible and ultraviolet wavelengths ratios are lower in the morning and evening and higher at noon. Visible and ultraviolet wavelength surface albedo is affected by 5-cm soil moisture, demonstrating a significant negative correlation. Excluding near-infrared wavelengths, correlations between surface albedo and 5-cm soil moisture pass the 99% confidence test at each wavelength. The correlation with 5-cm soil moisture is more significant at shorter wavelengths. However, this study obtained surface spectral radiation

  3. Mostly surfaces

    CERN Document Server

    Schwartz, Richard Evan

    2011-01-01

    This book presents a number of topics related to surfaces, such as Euclidean, spherical and hyperbolic geometry, the fundamental group, universal covering surfaces, Riemannian manifolds, the Gauss-Bonnet Theorem, and the Riemann mapping theorem. The main idea is to get to some interesting mathematics without too much formality. The book also includes some material only tangentially related to surfaces, such as the Cauchy Rigidity Theorem, the Dehn Dissection Theorem, and the Banach-Tarski Theorem. The goal of the book is to present a tapestry of ideas from various areas of mathematics in a clear and rigorous yet informal and friendly way. Prerequisites include undergraduate courses in real analysis and in linear algebra, and some knowledge of complex analysis.

  4. Surface rights

    Directory of Open Access Journals (Sweden)

    Regina Célia Corrêa Landim

    2009-06-01

    Full Text Available In many cities of Brazil, social inequality is illustrated by violence, poverty, and unemployment located next to luxurious residential towers and armored passenger cars. In the face of this situation, the National Movement of Urban Reform encouraged the inclusion of the social function of property in Brazil's new constitution of 1988. Surface rights represent an urbanistic instrument in the city statute that is best aligned to the constitutional principles and urban policies. The current article compares two laws that govern the principle of surface rights and provides a brief history of the evolution of the state based on illuminism and the consequent change in paradigm affecting individual rights, including property and civil rights, and their interpretation under the Constitution. The article concludes by suggesting the use of land surface rights in a joint operation, matching the ownership of the property with urban planning policies and social interest.

  5. An Experimental Study on the Pool Boiling Heat Transfer on a Square Surface

    International Nuclear Information System (INIS)

    Kim, Jae Kwang

    2000-02-01

    An experimental study was carried out to identify the various regimes of natural convective boiling and to determine the Critical Heat Flux (CHF) on a square surface. The basic knowledge on the boiling heat transfer and CHF on the square surface is necessary for various engineering problems, such as the design of compact heat exchangers, cooling of CPU chips, and design of the external cooling mechanism for the reactor during the severe accidents in the nuclear power plants. The heater block made of copper with cartridge heaters in it is submerged in a water tank with windows for visualization. The heater surface has dimension of 70mm x 70mm and the maximum heat flux capacity is about 1.8MW/m 2 . The boiling heat transfer coefficient for the various flow regimes up to CHF has been measured for upward facing surface, vertical surface, and nearly horizontal downward facing surfaces. The temperatures of the heater block are measured by the thermocouples imbedded in the heater block. As the heat flux increases from 100kW/m 2 to 1.0MW/m 2 , the heat-transfer regime changes from the nucleate boiling to the CHF. Near 1.0MW/m 2 , the heat transfer regime suddenly changed from nucleate boiling to film boiling and it resulted in a rapid heat up of the heater block. The various boiling patterns on the vertical surface, upward facing surface, and downward facing surface are observed by a high speed video camera whose frame rate is 1000fps. An explosive vapor generation on the heated surface, whose size and frequency are characterized by the heat flux and inclination angle, is observed

  6. Sensitivity of surface temperature to radiative forcing by contrail cirrus in a radiative-mixing model

    Directory of Open Access Journals (Sweden)

    U. Schumann

    2017-11-01

    Full Text Available Earth's surface temperature sensitivity to radiative forcing (RF by contrail cirrus and the related RF efficacy relative to CO2 are investigated in a one-dimensional idealized model of the atmosphere. The model includes energy transport by shortwave (SW and longwave (LW radiation and by mixing in an otherwise fixed reference atmosphere (no other feedbacks. Mixing includes convective adjustment and turbulent diffusion, where the latter is related to the vertical component of mixing by large-scale eddies. The conceptual study shows that the surface temperature sensitivity to given contrail RF depends strongly on the timescales of energy transport by mixing and radiation. The timescales are derived for steady layered heating (ghost forcing and for a transient contrail cirrus case. The radiative timescales are shortest at the surface and shorter in the troposphere than in the mid-stratosphere. Without mixing, a large part of the energy induced into the upper troposphere by radiation due to contrails or similar disturbances gets lost to space before it can contribute to surface warming. Because of the different radiative forcing at the surface and at top of atmosphere (TOA and different radiative heating rate profiles in the troposphere, the local surface temperature sensitivity to stratosphere-adjusted RF is larger for SW than for LW contrail forcing. Without mixing, the surface energy budget is more important for surface warming than the TOA budget. Hence, surface warming by contrails is smaller than suggested by the net RF at TOA. For zero mixing, cooling by contrails cannot be excluded. This may in part explain low efficacy values for contrails found in previous global circulation model studies. Possible implications of this study are discussed. Since the results of this study are model dependent, they should be tested with a comprehensive climate model in the future.

  7. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants....

  8. Simulation and transient analyses of a complete passive heat removal system in a downward cooling pool-type material testing reactor against a complete station blackout and long-term natural convection mode using the RELAP5/3.2 code

    Directory of Open Access Journals (Sweden)

    Afshin Hedayat

    2017-08-01

    Full Text Available In this paper, a complete station blackout (SBO or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR. The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank, safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal–hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

  9. Simulation and transient analyses of a complete passive heat removal system in a downward cooling pool-type material testing reactor against a complete station blackout and long-term natural convection mode using the RELAP5/3.2 code

    Energy Technology Data Exchange (ETDEWEB)

    Hedayat, Afshin [Reactor and Nuclear Safety School, Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of)

    2017-08-15

    In this paper, a complete station blackout (SBO) or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR). The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank), safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal–hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

  10. The Asian-Bering-North American teleconnection: seasonality, maintenance, and climate impact on North America

    Science.gov (United States)

    Yu, Bin; Lin, H.; Wu, Z. W.; Merryfield, W. J.

    2018-03-01

    The Asian-Bering-North American (ABNA) teleconnection index is constructed from the normalized 500-hPa geopotential field by excluding the Pacific-North American pattern contribution. The ABNA pattern features a zonally elongated wavetrain originating from North Asia and flowing downstream across Bering Sea and Strait towards North America. The large-scale teleconnection is a year-round phenomenon that displays strong seasonality with the peak variability in winter. North American surface temperature and temperature extremes, including warm days and nights as well as cold days and nights, are significantly controlled by this teleconnection. The ABNA pattern has an equivalent barotropic structure in the troposphere and is supported by synoptic-scale eddy forcing in the upper troposphere. Its associated sea surface temperature anomalies exhibit a horseshoe-shaped structure in the North Pacific, most prominent in winter, which is driven by atmospheric circulation anomalies. The snow cover anomalies over the West Siberian plain and Central Siberian Plateau in autumn and spring and over southern Siberia in winter may act as a forcing influence on the ABNA pattern. The snow forcing influence in winter and spring can be traced back to the preceding season, which provides a predictability source for this teleconnection and for North American temperature variability. The ABNA associated energy budget is dominated by surface longwave radiation anomalies year-round, with the temperature anomalies supported by anomalous downward longwave radiation and damped by upward longwave radiation at the surface.

  11. Simultaneous solution of the geoid and the surface density anomalies

    Science.gov (United States)

    Ardalan, A. A.; Safari, A.; Karimi, R.; AllahTavakoli, Y.

    2012-04-01

    The main application of the land gravity data in geodesy is "local geoid" or "local gravity field" modeling, whereas the same data could play a vital role for the anomalous mass-density modeling in geophysical explorations. In the realm of local geoid computations based on Geodetic Boundary Value Problems (GBVP), it is needed that the effect of the topographic (or residual terrain) masses be removed via application of the Newton integral in order to perform the downward continuation in a harmonic space. However, harmonization of the downward continuation domain may not be perfectly possible unless accurate information about the mass-density of the topographic masses be available. On the other hand, from the exploration point of view the unwanted topographical masses within the aforementioned procedure could be regarded as the signal. In order to overcome the effect of the remaining masses within the remove step of the GBVP, which cause uncertainties in mathematical modeling of the problem, here we are proposing a methodology for simultaneous solution of the geoid and residual surface density modeling In other words, a new mathematical model will be offered which both provides the needed harmonic space for downward continuation and at the same time accounts for the non-harmonic terms of gravitational field and makes use of it for residual mass density modeling within the topographic region. The presented new model enjoys from uniqueness of the solution, opposite to the inverse application of the Newton integral for mass density modeling which is non-unique, and only needs regularization to remove its instability problem. In this way, the solution of the model provides both the incremental harmonic gravitational potential on surface of the reference ellipsoid as the gravity field model and the lateral surface mass-density variations via the second derivatives of the non harmonic terms of gravitational field. As the case study and accuracy verification, the proposed

  12. How much can Greenland melt? An upper bound on mass loss from the Greenland Ice Sheet through surface melting

    Science.gov (United States)

    Liu, X.; Bassis, J. N.

    2015-12-01

    With observations showing accelerated mass loss from the Greenland Ice Sheet due to surface melt, the Greenland Ice Sheet is becoming one of the most significant contributors to sea level rise. The contribution of the Greenland Ice Sheet o sea level rise is likely to accelerate in the coming decade and centuries as atmospheric temperatures continue to rise, potentially triggering ever larger surface melt rates. However, at present considerable uncertainty remains in projecting the contribution to sea level of the Greenland Ice Sheet both due to uncertainty in atmospheric forcing and the ice sheet response to climate forcing. Here we seek an upper bound on the contribution of surface melt from the Greenland to sea level rise in the coming century using a surface energy balance model coupled to an englacial model. We use IPCC Representative Concentration Pathways (RCP8.5, RCP6, RCP4.5, RCP2.6) climate scenarios from an ensemble of global climate models in our simulations to project the maximum rate of ice volume loss and related sea-level rise associated with surface melting. To estimate the upper bound, we assume the Greenland Ice Sheet is perpetually covered in thick clouds, which maximize longwave radiation to the ice sheet. We further assume that deposition of black carbon darkens the ice substantially turning it nearly black, substantially reducing its albedo. Although assuming that all melt water not stored in the snow/firn is instantaneously transported off the ice sheet increases mass loss in the short term, refreezing of retained water warms the ice and may lead to more melt in the long term. Hence we examine both assumptions and use the scenario that leads to the most surface melt by 2100. Preliminary models results suggest that under the most aggressive climate forcing, surface melt from the Greenland Ice Sheet contributes ~1 m to sea level by the year 2100. This is a significant contribution and ignores dynamic effects. We also examined a lower bound

  13. Surface energy budget and turbulent fluxes at Arctic terrestrial sites

    Science.gov (United States)

    Grachev, Andrey; Persson, Ola; Uttal, Taneil; Konopleva-Akish, Elena; Crepinsek, Sara; Cox, Christopher; Fairall, Christopher; Makshtas, Alexander; Repina, Irina

    2017-04-01

    imbalance magnitude. All turbulent fluxes are highly correlated with net radiation because this balance between solar and longwave radiation is the principal energy source for daytime surface warming, evaporation, and photosynthesis. We find that turbulent fluxes of carbon dioxide and sensible heat are closely linked and, on average, change sign synchronously during the diurnal and annual cycles. The work is supported by the NOAA Climate Program Office, the U.S. National Science Foundation (NSF) with award ARC 11-07428, and by the U.S. Civilian Research & Development Foundation (CRDF) with award RUG1-2976-ST-10.

  14. Electric field stabilization of viscous liquid layers coating the underside of a surface

    Science.gov (United States)

    Anderson, Thomas G.; Cimpeanu, Radu; Papageorgiou, Demetrios T.; Petropoulos, Peter G.

    2017-05-01

    We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a horizontal surface in the presence of an electric field applied parallel to the surface. The model includes the effect of bounding solid dielectric regions above and below the liquid-air system that are typically found in experiments. The competition between gravitational forces, surface tension, and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semispectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations using the volume-of-fluid methodology and assess the accuracy of the obtained solutions in the long-wave (thin-film) regime when varying the electric field strength from zero up to the point when complete stabilization occurs. We employ DNS to examine the limitations of the asymptotically derived behavior as the liquid layer thickness increases and find excellent agreement even beyond the regime of strict applicability of the asymptotic solution. Finally, the asymptotic and computational approaches are utilized to identify robust and efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

  15. Surface temperatures in New York City: Geospatial data enables the accurate prediction of radiative heat transfer.

    Science.gov (United States)

    Ghandehari, Masoud; Emig, Thorsten; Aghamohamadnia, Milad

    2018-02-02

    Despite decades of research seeking to derive the urban energy budget, the dynamics of thermal exchange in the densely constructed environment is not yet well understood. Using New York City as a study site, we present a novel hybrid experimental-computational approach for a better understanding of the radiative heat transfer in complex urban environments. The aim of this work is to contribute to the calculation of the urban energy budget, particularly the stored energy. We will focus our attention on surface thermal radiation. Improved understanding of urban thermodynamics incorporating the interaction of various bodies, particularly in high rise cities, will have implications on energy conservation at the building scale, and for human health and comfort at the urban scale. The platform presented is based on longwave hyperspectral imaging of nearly 100 blocks of Manhattan, in addition to a geospatial radiosity model that describes the collective radiative heat exchange between multiple buildings. Despite assumptions in surface emissivity and thermal conductivity of buildings walls, the close comparison of temperatures derived from measurements and computations is promising. Results imply that the presented geospatial thermodynamic model of urban structures can enable accurate and high resolution analysis of instantaneous urban surface temperatures.

  16. Surface smoothness

    DEFF Research Database (Denmark)

    Tummala, Sudhakar; Dam, Erik B.

    2010-01-01

    accuracy, such novel markers must therefore be validated against clinically meaningful end-goals such as the ability to allow correct diagnosis. We present a method for automatic cartilage surface smoothness quantification in the knee joint. The quantification is based on a curvature flow method used....... We demonstrate that the fully automatic markers eliminate the time required for radiologist annotations, and in addition provide a diagnostic marker superior to the evaluated semi-manual markers....

  17. Adsorption properties of AlN on Si(111) surface: A density functional study

    Science.gov (United States)

    Yuan, Yinmei; Zuo, Ran; Mao, Keke; Tang, Binlong; Zhang, Zhou; Liu, Jun; Zhong, Tingting

    2018-04-01

    In the process of preparing GaN on Si substrate by MOCVD, an AlN buffer layer is very important. In this study, we conducted density functional theory calculations on the adsorption of AlN molecule on Si(111)-(2 × 2) surface, with the AlN molecule located horizontally or vertically above Si(111) surface at different adsorption sites. The calculations revealed that the lowest adsorption energy was at the N-top-Al-bridge site in the horizontal configuration, with the narrowest band gap, indicating that it was the most preferential adsorption growth status of AlN. In the vertical configurations, N adatom was more reactive and convenient to form bonds with the topmost Si atoms than Al adatom. When the N-end of the AlN molecule was located downward, the hollow site was the preferred adsorption site; when the Al-end was located downward, the bridge site was the most energetically favorable. Moreover, we investigated some electronic properties such as partial density of states, electron density difference, Mulliken populations, etc., revealing the microscale mechanism for AlN adsorption on Si(111) surface and providing theoretical support for adjusting the processing parameters during AlN or GaN production.

  18. One-dimensional critical heat flux concerning surface orientation and gap size effects

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Hoon; Suh, Kune Y. E-mail: kysuh@snu.ac.kr

    2003-12-01

    Tests were conducted to examine the critical heat flux (CHF) on a one-dimensional downward heating rectangular channel having a narrow gap by changing the orientation of the copper test heater assembly in a pool of saturated water under atmospheric pressure. The test parameters include both the gap sizes of 1, 2, 5 and 10 mm, and the surface orientation angles from the downward-facing position (180 deg.) to the vertical position (90 deg.), respectively. Also, the CHF experiments were performed for pool boiling with varying heater surface orientations in the unconfined space at atmospheric pressure using the rectangular test section. It was observed that the CHF generally decreases as the surface inclination angle increases and as the gap size decreases. In consistency with several studies reported in the literature, it was found that there exists a transition angle at which the CHF changes with a rapid slope. An engineering correlation is developed for the CHF during natural convective boiling in the inclined, confined rectangular channels with the aid of dimensional analysis. This correlation agrees with the experimental data of this study within {+-}20%.

  19. Analysis of MAGSAT and surface data of the Indian region

    Science.gov (United States)

    Agarwal, G. C. (Principal Investigator)

    1983-01-01

    Techniques and significant results of an analysis of MAGSAT and surface data of the Indian region are described. Specific investigative tasks included: (1) use of the multilevel data at different altitudes to develop a model for variation of magnetic anomaly with altitude; (2) development of the regional model for the description of main geomagnetic field for the Indian sub-continent using MAGSAT and observatory data; (3) development of regional mathematical model of secular variations over the Indian sub-continent; and (4) downward continuation of the anomaly field obtained from MAGSAT and its combination with the existing observatory data to produce a regional anomaly map for elucidating tectonic features of the Indian sub-continent.

  20. Surface formation, preservation, and history of low-porosity crusts at the WAIS Divide site, West Antarctica

    Science.gov (United States)

    Fegyveresi, John M.; Alley, Richard B.; Muto, Atsuhiro; Orsi, Anaïs J.; Spencer, Matthew K.

    2018-01-01

    Observations at the West Antarctic Ice Sheet (WAIS) Divide site show that near-surface snow is strongly altered by weather-related processes such as strong winds and temperature fluctuations, producing features that are recognizable in the deep ice core. Prominent glazed surface crusts develop frequently at the site during summer seasons. Surface, snow pit, and ice core observations made in this study during summer field seasons from 2008-2009 to 2012-2013, supplemented by automated weather station (AWS) data with short- and longwave radiation sensors, revealed that such crusts formed during relatively low-wind, low-humidity, clear-sky periods with intense daytime sunshine. After formation, such glazed surfaces typically developed cracks in a polygonal pattern likely from thermal contraction at night. Cracking was commonest when several clear days occurred in succession and was generally followed by surface hoar growth; vapor escaping through the cracks during sunny days may have contributed to the high humidity that favored nighttime formation of surface hoar. Temperature and radiation observations show that daytime solar heating often warmed the near-surface snow above the air temperature, contributing to upward mass transfer, favoring crust formation from below, and then surface hoar formation. A simple surface energy calculation supports this observation. Subsequent examination of the WDC06A deep ice core revealed that crusts are preserved through the bubbly ice, and some occur in snow accumulated during winters, although not as commonly as in summertime deposits. Although no one has been on site to observe crust formation during winter, it may be favored by greater wintertime wind packing from stronger peak winds, high temperatures and steep temperature gradients from rapid midwinter warmings reaching as high as -15 °C, and perhaps longer intervals of surface stability. Time variations in crust occurrence in the core may provide paleoclimatic information

  1. Linking atmospheric synoptic transport, cloud phase, surface energy fluxes, and sea-ice growth: observations of midwinter SHEBA conditions

    Science.gov (United States)

    Persson, P. Ola G.; Shupe, Matthew D.; Perovich, Don; Solomon, Amy

    2017-08-01

    Observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) project are used to describe a sequence of events linking midwinter long-range advection of atmospheric heat and moisture into the Arctic Basin, formation of supercooled liquid water clouds, enhancement of net surface energy fluxes through increased downwelling longwave radiation, and reduction in near-surface conductive heat flux loss due to a warming of the surface, thereby leading to a reduction in sea-ice bottom growth. The analyses provide details of two events during Jan. 1-12, 1998, one entering the Arctic through Fram Strait and the other from northeast Siberia; winter statistics extend the results. Both deep, precipitating frontal clouds and post-frontal stratocumulus clouds impact the surface radiation and energy budget. Cloud liquid water, occurring preferentially in stratocumulus clouds extending into the base of the inversion, provides the strongest impact on surface radiation and hence modulates the surface forcing, as found previously. The observations suggest a minimum water vapor threshold, likely case dependent, for producing liquid water clouds. Through responses to the radiative forcing and surface warming, this cloud liquid water also modulates the turbulent and conductive heat fluxes, and produces a thermal wave penetrating into the sea ice. About 20-33 % of the observed variations of bottom ice growth can be directly linked to variations in surface conductive heat flux, with retarded ice growth occurring several days after these moisture plumes reduce the surface conductive heat flux. This sequence of events modulate pack-ice wintertime environmental conditions and total ice growth, and has implications for the annual sea-ice evolution, especially for the current conditions of extensive thinner ice.

  2. Quantifying the Contributions of Environmental Parameters to Ceres Surface Net Radiation Error in China

    Science.gov (United States)

    Pan, X.; Yang, Y.; Liu, Y.; Fan, X.; Shan, L.; Zhang, X.

    2018-04-01

    Error source analyses are critical for the satellite-retrieved surface net radiation (Rn) products. In this study, we evaluate the Rn error sources in the Clouds and the Earth's Radiant Energy System (CERES) project at 43 sites from July in 2007 to December in 2007 in China. The results show that cloud fraction (CF), land surface temperature (LST), atmospheric temperature (AT) and algorithm error dominate the Rn error, with error contributions of -20, 15, 10 and 10 W/m2 (net shortwave (NSW)/longwave (NLW) radiation), respectively. For NSW, the dominant error source is algorithm error (more than 10 W/m2), particularly in spring and summer with abundant cloud. For NLW, due to the high sensitivity of algorithm and large LST/CF error, LST and CF are the largest error sources, especially in northern China. The AT influences the NLW error large in southern China because of the large AT error in there. The total precipitable water has weak influence on Rn error even with the high sensitivity of algorithm. In order to improve Rn quality, CF and LST (AT) error in northern (southern) China should be decreased.

  3. The clear-sky greenhouse effect sensitivity to a sea surface temperature change

    Science.gov (United States)

    Duvel, J. PH.; Breon, F. M.

    1991-01-01

    The clear-sky greenhouse effect response to a sea surface temperature (SST or Ts) change is studied using outgoing clear-sky longwave radiation measurements from the Earth Radiation Budget Experiment. Considering geographical distributions for July 1987, the relation between the SST, the greenhouse effect (defined as the outgoing infrared flux trapped by atmospheric gases), and the precipitable water vapor content (W), estimated by the Special Sensor Microwave Imager, is analyzed first. A fairly linear relation between W and the normalized greenhouse effect g, is found. On the contrary, the SST dependence of both W and g exhibits nonlinearities with, especially, a large increase for SST above 25 C. This enhanced sensitivity of g and W can be interpreted in part by a corresponding large increase of atmospheric water vapor content related to the transition from subtropical dry regions to equatorial moist regions. Using two years of data (1985 and 1986), the normalized greenhouse effect sensitivity to the sea surface temperature is computed from the interannual variation of monthly mean values.

  4. Surfaces of Building Practice

    OpenAIRE

    Surynková, Petra

    2009-01-01

    My diploma thesis Surfaces of Building Practice deals with the basic properties of surfaces, their mathematical description, categorization, and application in technical practice. Each studied surface is defined and its process of construction and parametrical description is listed. The thesis studies selected types of surfaces in details - these surfaces include surfaces of revolution, ruled surfaces, screw surfaces, and translational surfaces. An application of each studied surfaces is show...

  5. Water Entry and Exit of Horizontal Cylinder in Free Surface Flow

    International Nuclear Information System (INIS)

    Hafsia, Zouhaier; Maalel, Khlifa; Mnasri, Chokri; Mohamed, Omri

    2009-01-01

    This paper describes two-dimensional numerical simulations of the water entry and exit of horizontal circular cylinder at constant velocity. The deformation of free surface is described by Navier-Stokes (N S) equations of incompressible and viscous fluid with additional transport equation of the volume-of-fluid (VOF). The motion of the cylinder is modeled by the associated momentum source term implemented in the Phoenicis (Parabolic Hyperbolic Or Elliptic Numerical Integration Code Series) code. The domain is discretized by a fixed Cartesian grid using a finite volume method and the cylinder is represented and cut cell method. The simulated results are compared with the numerical results of Lin (2007). This comparison shows good agreement in terms of free surface evolution for water exit and sinking. However, for water entry, the jet flow simulated by Lin is not reproduced. The free surface deformation around the cylinder in downward direction is accurately predicted

  6. A hybrid model to predict the onset of gas entrainment with surface tension effects

    International Nuclear Information System (INIS)

    Saleh, W.; Bowden, R.C.; Hassan, I.G.; Kadem, L.

    2008-01-01

    The onset of gas entrainment, in a single downward oriented discharge from a stratified gas-liquid region with was modeled. The assumptions made in the development of the model reduced the problem to that of a potential flow. The discharge was modeled as a point-sink. Through use of the Kelvin-Laplace equation the model included the effects of surface tension. The resulting model required further knowledge of the flow field, specifically the dip radius of curvature prior to the onset of gas entrainment. The dip shape and size was investigated experimentally and correlations were provided to characterize the dip in terms of the discharge Froude number. The experimental correlation was used in conjunction with the theoretical model to predict the critical height. The results showed that by including surface tension effects the predicted critical height showed excellent agreement with experimental data. Surface tension reduces the critical height through the Bond number

  7. Mixed convection-radiation interaction in boundary-layer flow over horizontal surfaces

    Science.gov (United States)

    Ibrahim, F. S.; Hady, F. M.

    1990-06-01

    The effect of buoyancy forces and thermal radiation on the steady laminar plane flow over an isothermal horizontal flat plate is investigated within the framework of first-order boundary-layer theory, taking into account the hydrostatic pressure variation normal to the plate. The fluid considered is a gray, absorbing-emitting but nonscattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both a hot surface facing upward and a cold surface facing downward are considered in the analysis. Numerical results for the local Nusselt number, the local wall shear stress, the local surface heat flux, as well as the velocity and temperature distributions are presented for gases with a Prandtl number of 0.7 for various values of the radiation-conduction parameter, the buoyancy parameter, and the temperature ratio parameter.

  8. Photoelectric emission from negative-electron-affinity diamond (111) surfaces: Exciton breakup versus conduction-band emission

    International Nuclear Information System (INIS)

    Bandis, C.; Pate, B.B.

    1995-01-01

    We have recently reported that bound electron-hole pairs (Mott-Wannier excitons) are the dominant source of photoelectron emission from specially prepared [''as-polished'' C(111)-(1x1):H] negative-electron-affinity diamond surfaces for near-band-gap excitation up to 0.5 eV above threshold [C. Bandis and B. B. Pate, Phys. Rev. Lett. 74, 777 (1995)]. It was found that photoexcited excitons transport to the surface, break up, and emit their electron. In this paper, we extend the study of exciton-derived emission to include partial yield (constant final-state) analysis as well as angular distribution measurements of the photoelectric emission. In addition, we find that exciton-derived emission does not always dominate. Photoelectric emission properties of the in situ ''rehydrogenated'' (111)-(1x1):H diamond surface are characteristically different than emission observed from the as-polished (111)-(1x1):H surface. The rehydrogenated surface has additional downward band bending as compared to the as-polished surface. In confirmation of the assignment of photoelectric yield to exciton breakup emission, we find a significant enhancement of the total electron yield when the downward band bending of the hydrogenated surface is increased. The functional form of the observed total electron yield demonstrates that, in contrast to the as-polished surface, conduction-band electrons are a significant component of the observed photoelectric yield from the in situ hydrogenated (111)-(1x1):H surface. Furthermore, electron emission characteristics of the rehydrogenated surface confirms our assignment of a Fan phonon-cascade mechanism for thermalization of excitons

  9. Biphilic Surfaces for Enhanced Water Collection from Humid Air

    Science.gov (United States)

    Benkoski, Jason; Gerasopoulos, Konstantinos; Luedeman, William

    Surface wettability plays an important role in water recovery, distillation, dehumidification, and heat transfer. The efficiency of each process depends on the rate of droplet nucleation, droplet growth, and mass transfer. Unfortunately, hydrophilic surfaces are good at nucleation but poor at shedding. Hydrophobic surfaces are the reverse. Many plants and animals overcome this tradeoff through biphilic surfaces with patterned wettability. For example, the Stenocara beetle uses hydrophilic patches on a superhydrophobic background to collect fog from air. Cribellate spiders similarly collect fog on their webs through periodic spindle-knot structures. In this study, we investigate the effects of wettability patterns on the rate of water collection from humid air. The steady state rate of water collection per unit area is measured as a function of undercooling, angle of inclination, water contact angle, hydrophilic patch size, patch spacing, area fraction, and patch height relative to the hydrophobic background. We then model each pattern by comparing the potential and kinetic energy of a droplet as it rolls downwards at a fixed angle. The results indicate that the design rules for collecting fog differ from those for condensation from humid air. The authors gratefully acknowledge the Office of Naval Research for financial support through Grant Number N00014-15-1-2107.

  10. Fast simulation tool for ultraviolet radiation at the earth's surface

    Science.gov (United States)

    Engelsen, Ola; Kylling, Arve

    2005-04-01

    FastRT is a fast, yet accurate, UV simulation tool that computes downward surface UV doses, UV indices, and irradiances in the spectral range 290 to 400 nm with a resolution as small as 0.05 nm. It computes a full UV spectrum within a few milliseconds on a standard PC, and enables the user to convolve the spectrum with user-defined and built-in spectral response functions including the International Commission on Illumination (CIE) erythemal response function used for UV index calculations. The program accounts for the main radiative input parameters, i.e., instrumental characteristics, solar zenith angle, ozone column, aerosol loading, clouds, surface albedo, and surface altitude. FastRT is based on look-up tables of carefully selected entries of atmospheric transmittances and spherical albedos, and exploits the smoothness of these quantities with respect to atmospheric, surface, geometrical, and spectral parameters. An interactive site, http://nadir.nilu.no/~olaeng/fastrt/fastrt.html, enables the public to run the FastRT program with most input options. This page also contains updated information about FastRT and links to freely downloadable source codes and binaries.

  11. Experimental study of the effect of the reduced graphene oxide films on nucleate boiling performances of inclined surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Hoon; Kong, Byeong Tak [Incheon National University, Incheon (Korea, Republic of); Kim, Ji Min [POSTECH, Pohang (Korea, Republic of); and others

    2016-05-15

    For the enhancing the CHF, surface coating techniques are available. Yang et al. performed small scale boiling experiments for the vessel lower head, which was coated by aluminum/copper micro particles. Recently, graphene has received much attention for applications in thermal engineering due to its large thermal conductivity. Ahn et al. used a silicon dioxide substrate, which was coated graphene films, as a heating surface during pool boiling experiments. The graphene films inhibited the formation of hot spots, increasing the CHF. For applying novel material 'Graphene' in nuclear industry, here we investigated the effects of graphene film coatings on boiling performances. The experimental pool boiling facility, copying the geometry of lower head of reactor, was designed for verifying orientation effects. The effects of graphene films coating on varied inclined heater surfaces were investigated. The CHF values were increased at every case, but the increased amounts were decreased for downward heater surfaces. At the downward-facing region, however, coating the RGO films would change the CHF mechanisms and boiling heat transfer performances. Generally, RGO films, made by colloidal fabrication, has defects on each flakes.

  12. Experimental study of the effect of the reduced graphene oxide films on nucleate boiling performances of inclined surfaces

    International Nuclear Information System (INIS)

    Kim, Ji Hoon; Kong, Byeong Tak; Kim, Ji Min

    2016-01-01

    For the enhancing the CHF, surface coating techniques are available. Yang et al. performed small scale boiling experiments for the vessel lower head, which was coated by aluminum/copper micro particles. Recently, graphene has received much attention for applications in thermal engineering due to its large thermal conductivity. Ahn et al. used a silicon dioxide substrate, which was coated graphene films, as a heating surface during pool boiling experiments. The graphene films inhibited the formation of hot spots, increasing the CHF. For applying novel material 'Graphene' in nuclear industry, here we investigated the effects of graphene film coatings on boiling performances. The experimental pool boiling facility, copying the geometry of lower head of reactor, was designed for verifying orientation effects. The effects of graphene films coating on varied inclined heater surfaces were investigated. The CHF values were increased at every case, but the increased amounts were decreased for downward heater surfaces. At the downward-facing region, however, coating the RGO films would change the CHF mechanisms and boiling heat transfer performances. Generally, RGO films, made by colloidal fabrication, has defects on each flakes.

  13. Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

    Science.gov (United States)

    Xiao, Ziniu; Li, Delin

    2016-06-01

    The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

  14. Phonon-mediated decay of an atom in a surface-induced potential

    International Nuclear Information System (INIS)

    Kien, Fam Le; Hakuta, K.; Dutta Gupta, S.

    2007-01-01

    We study phonon-mediated transitions between translational levels of an atom in a surface-induced potential. We present a general master equation governing the dynamics of the translational states of the atom. In the framework of the Debye model, we derive compact expressions for the rates for both upward and downward transitions. Numerical calculations for the transition rates are performed for a deep silica-induced potential allowing for a large number of bound levels as well as free states of a cesium atom. The total absorption rate is shown to be determined mainly by the bound-to-bound transitions for deep bound levels and by bound-to-free transitions for shallow bound levels. Moreover, the phonon emission and absorption processes can be orders of magnitude larger for deep bound levels as compared to the shallow bound ones. We also study various types of transitions from free states. We show that, for thermal atomic cesium with a temperature in the range from 100 μK to 400 μK in the vicinity of a silica surface with a temperature of 300 K, the adsorption (free-to-bound decay) rate is about two times larger than the heating (free-to-free upward decay) rate, while the cooling (free-to-free downward decay) rate is negligible

  15. Self-energy behavior away from the Fermi surface in doped Mott insulators.

    Science.gov (United States)

    Merino, J; Gunnarsson, O; Kotliar, G

    2016-02-03

    We analyze self-energies of electrons away from the Fermi surface in doped Mott insulators using the dynamical cluster approximation to the Hubbard model. For large onsite repulsion, U, and hole doping, the magnitude of the self-energy for imaginary frequencies at the top of the band ([Formula: see text]) is enhanced with respect to the self-energy magnitude at the bottom of the band ([Formula: see text]). The self-energy behavior at these two [Formula: see text]-points is switched for electron doping. Although the hybridization is much larger for (0, 0) than for [Formula: see text], we demonstrate that this is not the origin of this difference. Isolated clusters under a downward shift of the chemical potential, [Formula: see text], at half-filling reproduce the overall self-energy behavior at (0, 0) and [Formula: see text] found in low hole doped embedded clusters. This happens although there is no change in the electronic structure of the isolated clusters. Our analysis shows that a downward shift of the chemical potential which weakly hole dopes the Mott insulator can lead to a large enhancement of the [Formula: see text] self-energy for imaginary frequencies which is not associated with electronic correlation effects, even in embedded clusters. Interpretations of the strength of electronic correlations based on self-energies for imaginary frequencies are, in general, misleading for states away from the Fermi surface.

  16. An analytical model for displacement velocity of liquid film on a hot vertical surface

    International Nuclear Information System (INIS)

    Yoshioka, Keisuke; Hasegawa, Shu

    1975-01-01

    The downward progress of the advancing front of a liquid film streaming down a heated vertical surface, as it would occur in emergency core cooling, is much slower than in the case of ordinary streaming down along a heated surface already wetted with the liquid. A two-dimensional heat conduction model is developed for evaluating this velocity of the liquid front, which takes account of the heat removal by ordinary flow boiling mechanism. In the analysis, the maximum heat flux and the calefaction temperature are taken up as parameters in addition to the initial dry heated wall temperature, the flow rate and the velocity of downward progress of the liquid front. The temperature profile is calculated for various combinations of these parameters. Two criteria are proposed for choosing the most suitable combination of the parameters. One is to reject solutions that represent an oscillating wall temperature distribution, and the second criterion requires that the length of the zone of violent boiling immediately following the liquid front should not be longer than about 1 mm, this value being determined from comparisons made between experiment and calculation. Application of the above two criteria resulted in reasonable values obtained for the calefaction temperature and the maximum heat flux, and the velocity of the liquid front derived therefrom showed good agreement with experiment. (auth.)

  17. Warm winds from the Pacific caused extensive Arctic sea-ice melt in summer 2007

    Energy Technology Data Exchange (ETDEWEB)

    Graversen, Rune G.; Drijfhout, Sybren [Royal Netherlands Meteorological Institute, De Bilt (Netherlands); Mauritsen, Thorsten [Max-Planck Institute for Meteorology, Hamburg (Germany); Tjernstroem, Michael; Maartensson, Sebastian [Stockholm University, Department of Meteorology, Stockholm (Sweden)

    2011-06-15

    During summer 2007 the Arctic sea-ice shrank to the lowest extent ever observed. The role of the atmospheric energy transport in this extreme melt event is explored using the state-of-the-art ERA-Interim reanalysis data. We find that in summer 2007 there was an anomalous atmospheric flow of warm and humid air into the region that suffered severe melt. This anomaly was larger than during any other year in the data (1989-2008). Convergence of the atmospheric energy transport over this area led to positive anomalies of the downward longwave radiation and turbulent fluxes. In the region that experienced unusual ice melt, the net anomaly of the surface fluxes provided enough extra energy to melt roughly one meter of ice during the melting season. When the ocean successively became ice-free, the surface-albedo decreased causing additional absorption of shortwave radiation, despite the fact that the downwelling solar radiation was smaller than average. We argue that the positive anomalies of net downward longwave radiation and turbulent fluxes played a key role in initiating the 2007 extreme ice melt, whereas the shortwave-radiation changes acted as an amplifying feedback mechanism in response to the melt. (orig.)

  18. Flange surface detection device for upper lid of reactor pressure vessel

    International Nuclear Information System (INIS)

    Kobayashi, Teruo.

    1996-01-01

    The present invention provide a device for detecting a flatness of an O-ring groove formed on a flange surface simply and at a high accuracy in a state where the upper lid of a reactor pressure vessel is removed as it is. Namely, a running truck provided with magnetic wheels is caused to run while being adsorbed along the outer circumferential surface of a downward flange surface and the lower surface of the flange in a state where the upper lid is removed. A sensor attaching stand equipped with spring-biased wheels is mounted to the running truck. The sensor attaching stand is provided with a flange surface sensor for measuring the distance to the lower surface of the flange and a groove sensor for measuring the distance to the bottom surface of an O-ring groove. Relative displacement of the groove sensor is determined by a calculator based on the measured value on the flange surface sensor. A flatness is obtained from the maximum value and the minimum value. In addition, presence of flaws on the bottom surface of the groove is detected based on the relative change of both measured values at the same time. As a result, all of the errors caused by the running are off-set thereby capable of performing a measurement at high accuracy. (I.S.)

  19. Observation of low-frequency acoustic surface waves in the nocturnal boundary layer.

    Science.gov (United States)

    Talmadge, Carrick L; Waxler, Roger; Di, Xiao; Gilbert, Kenneth E; Kulichkov, Sergey

    2008-10-01

    A natural terrain surface, because of its porosity, can support an acoustic surface wave that is a mechanical analog of the familiar vertically polarized surface wave in AM radio transmission. At frequencies of several hundred hertz, the acoustic surface wave is attenuated over distances of a few hundred meters. At lower frequencies (e.g., below approximately 200 Hz) the attenuation is much less, allowing surface waves to propagate thousands of meters. At night, a low-frequency surface wave is generally present at long ranges even when downward refraction is weak. Thus, surface waves represent a ubiquitous nighttime transmission mode that exists even when other transmission modes are weak or absent. Data from recent nighttime field experiments and theoretical calculations are presented, demonstrating the persistence of the surface wave under different meteorological conditions. The low-frequency surface wave described here is the "quasiharmonical" tail observed previously in nighttime measurements but not identified by S. Kulichkov and his colleagues (Chunchuzov, I. P. et al. 1990. "On acoustical impulse propagation in a moving inhomogeneous atmospheric layer," J. Acoust. Soc. Am. 88, 455-461).

  20. Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications

    Science.gov (United States)

    Minnis, P.; Smith, W., Jr.; Bedka, K. M.; Nguyen, L.; Palikonda, R.; Hong, G.; Trepte, Q.; Chee, T.; Scarino, B. R.; Spangenberg, D.; Sun-Mack, S.; Fleeger, C.; Ayers, J. K.; Chang, F. L.; Heck, P. W.

    2014-12-01

    Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-real time globally from both geostationary (GEO) and low-earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.

  1. Decomposing Shortwave Top-of-Atmosphere Radiative Flux Variability in Terms of Surface and Atmospheric Contributions Using CERES Observations

    Science.gov (United States)

    Loeb, N. G.; Wong, T.; Wang, H.

    2017-12-01

    Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, while the system cools by emitting outgoing longwave (LW) radiation to space. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget along with the associated atmospheric and surface properties that influence it. CERES data products utilize a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, polar orbiting and geostationary spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. Here we use simple diagnostic model of Earth's albedo and CERES Energy Balanced and Filled (EBAF) Ed4.0 data for March 2000-February 2016 to quantify interannual variations in SW TOA flux associated with surface albedo and atmospheric reflectance and transmittance variations. Surface albedo variations account for cloud properties over the Arctic Ocean.

  2. Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications

    Science.gov (United States)

    Minnis, Patrick; Smith, William L., Jr.; Bedka, Kristopher M.; Nguyen, Louis; Palikonda, Rabindra; Hong, Gang; Trepte, Qing Z.; Chee, Thad; Scarino, Benjamin; Spangenberg, Douglas A.; hide

    2014-01-01

    Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-­-real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-­-real time globally from both geostationary (GEO) and low-­-earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.

  3. Description of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    International Nuclear Information System (INIS)

    Johansson, Per-Olof

    2008-12-01

    This report describes the modelling of the surface hydrology and near-surface hydrogeology that was performed for the final site descriptive model of Forsmark produced in the site investigation stage, SDM-Site Forsmark. The comprehensive investigation and monitoring programme forms a strong basis for the developed conceptual and descriptive model of the hydrological and near-surface hydrological system of the site investigation area. However, there are some remaining uncertainties regarding the interaction of deep and near-surface groundwater and surface water of importance for the understanding of the system: The groundwaters in till below Lake Eckarfjaerden, Lake Gaellbotraesket, Lake Fiskarfjaerden and Lake Bolundsfjaerden have high salinities. The hydrological and hydrochemical interpretations indicate that these waters are relict waters of mainly marine origin. From the perspective of the overall water balance, the water below the central parts of the lakes can be considered as stagnant. However, according to the hydrochemical interpretation, these waters also contain weak signatures of deep saline water. Rough chloride budget calculations for the Gaellbotraesket depression also raise the question of a possible upward flow of deep groundwater. No absolute conclusion can be drawn from the existing data analyses regarding the key question of whether there is a small ongoing upward flow of deep saline water. However, Lake Bolundsfjaerden is an exception where the clear downward flow gradient from the till to the bedrock excludes the possibility of an active deep saline source. The available data indicate that there are no discharge areas for flow systems involving deep bedrock groundwater in the northern part of the tectonic lens, where the repository is planned to be located (the so-called 'target area'). However, it can not be excluded that such discharge areas exist. Data indicate that the prevailing downward vertical flow gradients from the QD to the bedrock

  4. Description of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Per-Olof (Artesia Grundvattenkonsult AB, Taeby (Sweden))

    2008-12-15

    This report describes the modelling of the surface hydrology and near-surface hydrogeology that was performed for the final site descriptive model of Forsmark produced in the site investigation stage, SDM-Site Forsmark. The comprehensive investigation and monitoring programme forms a strong basis for the developed conceptual and descriptive model of the hydrological and near-surface hydrological system of the site investigation area. However, there are some remaining uncertainties regarding the interaction of deep and near-surface groundwater and surface water of importance for the understanding of the system: The groundwaters in till below Lake Eckarfjaerden, Lake Gaellbotraesket, Lake Fiskarfjaerden and Lake Bolundsfjaerden have high salinities. The hydrological and hydrochemical interpretations indicate that these waters are relict waters of mainly marine origin. From the perspective of the overall water balance, the water below the central parts of the lakes can be considered as stagnant. However, according to the hydrochemical interpretation, these waters also contain weak signatures of deep saline water. Rough chloride budget calculations for the Gaellbotraesket depression also raise the question of a possible upward flow of deep groundwater. No absolute conclusion can be drawn from the existing data analyses regarding the key question of whether there is a small ongoing upward flow of deep saline water. However, Lake Bolundsfjaerden is an exception where the clear downward flow gradient from the till to the bedrock excludes the possibility of an active deep saline source. The available data indicate that there are no discharge areas for flow systems involving deep bedrock groundwater in the northern part of the tectonic lens, where the repository is planned to be located (the so-called 'target area'). However, it can not be excluded that such discharge areas exist. Data indicate that the prevailing downward vertical flow gradients from the QD to

  5. Temperate forest impacts on maritime snowpacks across an elevation gradient: An assessment of the snow surface energy balance and airborne lidar derived forest structure

    Science.gov (United States)

    Roth, T. R.; Nolin, A. W.

    2016-12-01

    Temperate forests modify snow evolution patterns both spatially and temporally relative to open areas. Dense, warm forests both impede snow accumulation through increased canopy snow interception and increase sub-canopy longwave energy inputs onto the snow surface. These process modifications vary in magnitude and duration depending on climatic, topographic and forest characteristics. Here we present results from a four year study of paired forested and open sites at three elevations, Low - 1150 m, Mid - 1325 m and High - 1465 m. Snowpacks are deeper and last up to 3-4 weeks longer at the Low and Mid elevation Open sites relative to the adjacent Forest sites. Conversely, at the High Forest site, snow is retained 2-4 weeks longer than the Open site. This change in snowpack depth and persistence is attributed to deposition patterns at higher elevations and forest structure differences that alter the canopy interception efficiency and the sub-canopy energy balance. Canopy interception efficiency (CIE) in the Low and Mid Forest sites, over the duration of the study were 79% and 76% of the total event snowfall, whereas CIE was 31% at the High Forest site. Longwave radiation in forested environments is the primary energy component across each elevation band due to the warm winter environment and forest presence, accounting for 82%, 88%, and 59% of the energy balance at the Low, Mid, and High Forest sites, respectively. High wind speeds in the High elevation Open site significantly increases the turbulent energy and creates preferential snowfall deposition in the nearby Forest site. These results show the importance of understanding the effects of forest cover on sub-canopy snowpack evolution and highlight the need for improved forest cover model representation to accurately predict water resources in maritime forests.

  6. Spin-polarized scanning tunneling spectroscopy of self-organized nanoscale Co islands on Au(111) surfaces.

    Science.gov (United States)

    Schouteden, K; Muzychenko, D A; Van Haesendonck, C

    2008-07-01

    Magnetic monolayer and bilayer Co islands of only a few nanometer in size were grown by atomic deposition on atomically flat Au(111) films. The islands were studied in situ by scanning tunneling microscopy (STM) and spectroscopy at low temperatures. Spin-resolved tunneling spectroscopy, using an STM tip with a magnetic coating, revealed that the Co islands exhibit a net magnetization perpendicular to the substrate surface due to the presence of spin-polarized d-states. A random distribution of islands with either upward or downward pointing magnetization was observed, without any specific correlation of magnetization orientation with island size or island height.

  7. Final Report for “Simulating the Arctic Winter Longwave Indirect Effects. A New Parameterization for Frost Flower Aerosol Salt Emissions” (DESC0006679) for 9/15/2011 through 9/14/2015

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Lynn M. [Univ. of California, San Diego, CA (United States); Somerville, Richard C.J. [Univ. of California, San Diego, CA (United States); Burrows, Susannah [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rasch, Phil [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-12-12

    Description of the Project: This project has improved the aerosol formulation in a global climate model by using innovative new field and laboratory observations to develop and implement a novel wind-driven sea ice aerosol flux parameterization. This work fills a critical gap in the understanding of clouds, aerosol, and radiation in polar regions by addressing one of the largest missing particle sources in aerosol-climate modeling. Recent measurements of Arctic organic and inorganic aerosol indicate that the largest source of natural aerosol during the Arctic winter is emitted from crystal structures, known as frost flowers, formed on a newly frozen sea ice surface [Shaw et al., 2010]. We have implemented the new parameterization in an updated climate model making it the first capable of investigating how polar natural aerosol-cloud indirect effects relate to this important and previously unrecognized sea ice source. The parameterization is constrained by Arctic ARM in situ cloud and radiation data. The modified climate model has been used to quantify the potential pan-Arctic radiative forcing and aerosol indirect effects due to this missing source. This research supported the work of one postdoc (Li Xu) for two years and contributed to the training and research of an undergraduate student. This research allowed us to establish a collaboration between SIO and PNNL in order to contribute the frost flower parameterization to the new ACME model. One peer-reviewed publications has already resulted from this work, and a manuscript for a second publication has been completed. Additional publications from the PNNL collaboration are expected to follow.

  8. Parametric influence of powerful radiation on plasma surface

    International Nuclear Information System (INIS)

    Kuklin, V.M.; Panchenko, I.P.; Chernousenko, V.M.

    1989-01-01

    A self-consistent set of equations that describes one-dimensional dynamics to develop the instability of long-wave intensive Langmuir wave is obtained and solved. The parametric instability influence on the character of absorption of the incident radiation energy is elucidated primarily. 40 refs.; 8 figs

  9. Surface excitation parameter for rough surfaces

    International Nuclear Information System (INIS)

    Da, Bo; Salma, Khanam; Ji, Hui; Mao, Shifeng; Zhang, Guanghui; Wang, Xiaoping; Ding, Zejun

    2015-01-01

    Graphical abstract: - Highlights: • Instead of providing a general mathematical model of roughness, we directly use a finite element triangle mesh method to build a fully 3D rough surface from the practical sample. • The surface plasmon excitation can be introduced to the realistic sample surface by dielectric response theory and finite element method. • We found that SEP calculated based on ideal plane surface model are still reliable for real sample surface with common roughness. - Abstract: In order to assess quantitatively the importance of surface excitation effect in surface electron spectroscopy measurement, surface excitation parameter (SEP) has been introduced to describe the surface excitation probability as an average number of surface excitations that electrons can undergo when they move through solid surface either in incoming or outgoing directions. Meanwhile, surface roughness is an inevitable issue in experiments particularly when the sample surface is cleaned with ion beam bombardment. Surface roughness alters not only the electron elastic peak intensity but also the surface excitation intensity. However, almost all of the popular theoretical models for determining SEP are based on ideal plane surface approximation. In order to figure out whether this approximation is efficient or not for SEP calculation and the scope of this assumption, we proposed a new way to determine the SEP for a rough surface by a Monte Carlo simulation of electron scattering process near to a realistic rough surface, which is modeled by a finite element analysis method according to AFM image. The elastic peak intensity is calculated for different electron incident and emission angles. Assuming surface excitations obey the Poisson distribution the SEPs corrected for surface roughness are then obtained by analyzing the elastic peak intensity for several materials and for different incident and emission angles. It is found that the surface roughness only plays an

  10. Sedimentation and fouling of optical surfaces at the ANTARES site

    Science.gov (United States)

    ANTARES Collaboration; CAU CEFREM Collaboration; Amram, P.; Anghinolfi, M.; Anvar, S.; Ardellier-Desages, F. E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Bellotti, R.; Beltramelli, J.; Benhammou, Y.; Berthier, R.; Bertin, V.; Billault, M.; Blaes, R.; Bland, R. W.; Blondeau, F.; de Botton, N.; Boulesteix, J.; Brooks, C. B.; Brunner, J.; Cafagna, F.; Calzas, A.; Capone, A.; Caponetto, L.; Cârloganu, C.; Carmona, E.; Carr, J.; Cartwright, S. L.; Cecchini, S.; Ciacio, F.; Circella, M.; Compère, C.; Cooper, S.; Coyle, P.; Cuneo, S.; Danilov, M.; van Dantzig, R.; de Marzo, C.; Destelle, J.-J.; de Vita, R.; Dispau, G.; Druillole, F.; Engelen, J.; Feinstein, F.; Ferdi, C.; Festy, D.; Fopma, J.; Gallone, J.-M.; Giacomelli, G.; Goret, P.; Gournay, J.-F.; Hallewell, G.; Heijboer, A.; Hernández-Rey, J. J.; Hubbard, J. R.; Jaquet, M.; de Jong, M.; Karolak, M.; Keller, P.; Kooijman, P.; Kouchner, A.; Kudryavtsev, V. A.; Lafoux, H.; Lagier, P.; Lamare, P.; Languillat, J.-C.; Laubier, L.; Laugier, J.-P.; Leilde, B.; Le Provost, H.; Le van Suu, A.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazeau, B.; Mazure, A.; McMillan, J. E.; Migneco, E.; Millot, C.; Mols, P.; Montanet, F.; Montaruli, T.; Moscoso, L.; Musumeci, M.; Nezri, E.; Nooren, G. J.; Oberski, J. E. J.; Olivetto, C.; Oppelt-Pohl, A.; Palanque-Delabrouille, N.; Papaleo, R.; Payre, P.; Perrin, P.; Petruccetti, M.; Petta, C.; Piattelli, P.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raia, G.; Randazzo, N.; Rethore, F.; Riccobene, G.; Ricol, J.-S.; Ripani, M.; Roca-Blay, V.; Romeyer, A.; Rostovstev, A.; Russo, G. V.; Sacquin, Y.; Salusti, E.; Schuller, J.-P.; Schuster, W.; Soirat, J.-P.; Souvorova, O.; Spooner, N. J. C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Tao, C.; Thompson, L. F.; Tilav, S.; Triay, R.; Usik, A.; Valdy, P.; Valente, V.; Varlamov, I.; Vaudaine, G.; Vernin, P.; Vladimirsky, E.; Vorobiev, M.; de Witt Huberts, P.; de Wolf, E.; Zakharov, V.; Zavatarelli, S.; Zornoza, Juan de Dios; Zún~Iga, J.; Aloïsi, J.-C.; Kerhervé, Ph.; Monaco, A.

    2003-05-01

    ANTARES is a project leading towards the construction and deployment of a neutrino telescope in the deep Mediterranean Sea. The telescope will use an array of photomultiplier tubes to detect the Cherenkov light emitted by muons resulting from the interaction with matter of high energy neutrinos. In the vicinity of the deployment site the ANTARES Collaboration has performed a series of in situ measurements to study the change in light transmission through glass surfaces during immersions of several months. The average loss of light transmission is estimated to be only ~2% at the equator of a glass sphere one year after deployment. It decreases with increasing zenith angle, and tends to saturate with time. The transmission loss, therefore, is expected to remain small for the several year lifetime of the ANTARES detector whose optical modules are oriented downwards. The measurements were complemented by the analysis of the 210Pb activity profile in sediment cores and the study of biofouling on glass plates. Despite a significant sedimentation rate at the site, in the 0.02-0.05 cmyr-1 range, the sediments adhere loosely to the glass surfaces and can be washed off by water currents. Further, fouling by deposits of light-absorbing particulates is only significant for surfaces facing upwards.

  11. Effect of reflective surfaces on a greenhouse lettuce crop

    Energy Technology Data Exchange (ETDEWEB)

    Warman, P.R.; Mayhew, W.J.

    1979-01-01

    The Canadian greenhouse industry is an important segment of horticultural production, providing employment for thousands of people. Continuing increases in the costs of conventional fuel supplies, however, has placed the industry in some jeopardy since the cost of heating during the winter months is also escalating. In response to this problem the Brace Research Institute has developed a single roofed greenhouse designed to capture and store the sun's energy, and to increase the amount of downward solar radiation inside the greenhouse through the use of specularly-reflecting back and side walls. The research investigated the effect of a reflective surface on plant growth, development, and nutritional uptake during fall and the early months of winter. The inside walls of the greenhouse were lined with aluminized polyester to act as a reflective surface and flat black roofing felt paper to provide a non-reflecting surface. Grand Rapids Forcing lettuce was planted from seed into a peat-vermiculite bed and total solar radiation was monitored on the horizontal. Over the duration of the experiment, the reflective side of the greenhouse received more than twice as much solar radiation as the non-reflective side leading to significantly larger plant yields on the reflective side. There were no significant differences in the uptake of the plant macronutrients, N, P, K, Ca, and Mg.

  12. An intercomparison and validation of satellite-based surface radiative energy flux estimates over the Arctic

    Science.gov (United States)

    Riihelä, Aku; Key, Jeffrey R.; Meirink, Jan Fokke; Kuipers Munneke, Peter; Palo, Timo; Karlsson, Karl-Göran

    2017-05-01

    Accurate determination of radiative energy fluxes over the Arctic is of crucial importance for understanding atmosphere-surface interactions, melt and refreezing cycles of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite-based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative flux estimates from Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1-degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water Cycle Experiment (GEWEX) surface energy budget, and our own experimental FluxNet / Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg flux estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave flux in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave flux over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer-based GEWEX and FluxNet-CLARA flux estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the FluxNet-CLARA downwelling shortwave flux is shown to be an overestimated cloud optical thickness. The results illustrate that satellite-based flux estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in flux retrievals.

  13. Clean Os(0001) electronic surface states: A first-principle fully relativistic investigation

    Science.gov (United States)

    Urru, Andrea; Dal Corso, Andrea

    2018-05-01

    We analyze the electronic structure of the Os(0001) surface by means of first-principle calculations based on Fully Relativistic (FR) Density Functional Theory (DFT) and a Projector Augmented-Wave (PAW) approach. We investigate surface states and resonances analyzing their spin-orbit induced energy splitting and their spin polarization. The results are compared with previously studied surfaces Ir(111), Pt(111), and Au(111). We do not find any surface state in the gap similar to the L-gap of the (111) fcc surfaces, but find Rashba split resonances that cross the Fermi level and, as in the recently studied Ir(111) surface, have a characteristic downward dispersion. Moreover, for some selected surface states we study the spin polarization with respect to k∥, the wave-vector parallel to the surface. In some cases, such as the Rashba split resonances, the spin polarization shows a smooth behavior with slow rotations, in others the rotation is faster, due to mixing and anti-crossing of the states.

  14. Impact of potassium and water on the electronic properties of InN(0001) surfaces

    International Nuclear Information System (INIS)

    Reiss, S.; Eisenhardt, A.; Krischok, S.; Himmerlich, M.

    2014-01-01

    In this work we investigate the interaction of potassium and water with 2 x 2 reconstructed InN(0001) surfaces prepared by plasma-assisted molecular beam epitaxy. The influence of adsorbate-substrate-interaction on surface properties is characterized in-situ by photoelectron spectroscopy. Potassium exposure leads to a strong reduction in the work function Φ to 1.6 eV revealing a charge transfer from the adsorbate to the InN surface. In parallel, a reduction of the surface downward band bending by 0.2 eV and hence a reduced electron accumulation density is observed. While interaction of water with clean InN(0001)-2 x 2 surfaces induces only minor changes in the surface band bending, water adsorption at potassium covered InN(0001) leads to a reversal of the K-induced reduction in surface band bending and a slight increase of Φ to 2.4 eV. These results show that surrounding water modifies the interaction of potassium with InN(0001) surfaces. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Diffusion Filters for Variational Data Assimilation of Sea Surface Temperature in an Intermediate Climate Model

    Directory of Open Access Journals (Sweden)

    Xuefeng Zhang

    2015-01-01

    Full Text Available Sequential, adaptive, and gradient diffusion filters are implemented into spatial multiscale three-dimensional variational data assimilation (3DVAR as alternative schemes to model background error covariance matrix for the commonly used correction scale method, recursive filter method, and sequential 3DVAR. The gradient diffusion filter (GDF is verified by a two-dimensional sea surface temperature (SST assimilation experiment. Compared to the existing DF, the new GDF scheme shows a superior performance in the assimilation experiment due to its success in extracting the spatial multiscale information. The GDF can retrieve successfully the longwave information over the whole analysis domain and the shortwave information over data-dense regions. After that, a perfect twin data assimilation experiment framework is designed to study the effect of the GDF on the state estimation based on an intermediate coupled model. In this framework, the assimilation model is subject to “biased” initial fields from the “truth” model. While the GDF reduces the model bias in general, it can enhance the accuracy of the state estimation in the region that the observations are removed, especially in the South Ocean. In addition, the higher forecast skill can be obtained through the better initial state fields produced by the GDF.

  16. Observations of climate, albedo, and surface radiation over cleared and undisturbed Amazonian forest

    International Nuclear Information System (INIS)

    Bastable, H.G.; Shuttleworth, W.J.; Dallarosa, R.L.G.; Fisch, G.; Nobre, C.A.

    1993-01-01

    Measurements from the first comparative study of climate over Amazonian tropical forest and an embedded deforested clearing are presented. Observations comprise a continuous 60-day run of data from mid-October to mid-December 1990, covering the end of the dry season and the beginning of the wet season. Mean hourly observations are calculated for the whole period; and for two 10-day periods, one in the dry season and one at the start of the wet season. Much greater variation in weather variables was observed at the clearing compared with over the forest. While the mean values of temperature and specific humidity deficit differed by less than 1°C and 1 g kg −1 respectively, their daily ranges at the clearing were twice those at the forest. Mean daily albedo of the forest was 13.1 per cent, agreeing well with other tropical forest measurements, and of the clearing was 16.3 per cent, somewhat lower than the values currently being used in GCMs. The surface energy balance was investigated and mean available energy calculated for each site. The significant difference in the daily pattern of net radiation between the sites was found to be at least as much due to differences in the longwave radiation balance as to differences in albedo. The diurnal pattern of net radiation therefore changed between dry and wet periods as the higher plant water stress experienced by clearing vegetation altered the daily temperature cycle

  17. A Smart Irrigation Approach Aided by Monitoring Surface Soil Moisture using Unmanned Aerial Vehicles

    Science.gov (United States)

    Wienhold, K. J.; Li, D.; Fang, N. Z.

    2017-12-01

    Soil moisture is a critical component in the optimization of irrigation scheduling in water resources management. Unmanned Aerial Vehicles (UAV) equipped with multispectral sensors represent an emerging technology capable of detecting and estimating soil moisture for irrigation and crop management. This study demonstrates a method of using a UAV as an optical and thermal remote sensing platform combined with genetic programming to derive high-resolution, surface soil moisture (SSM) estimates. The objective is to evaluate the feasibility of spatially-variable irrigation management for a golf course (about 50 acres) in North Central Texas. Multispectral data is collected over the course of one month in the visible, near infrared and longwave infrared spectrums using a UAV capable of rapid and safe deployment for daily estimates. The accuracy of the model predictions is quantified using a time domain reflectometry (TDR) soil moisture sensor and a holdout validation test set. The model produces reasonable estimates for SSM with an average coefficient of correlation (r) = 0.87 and coefficient of determination of (R2) = 0.76. The study suggests that the derived SSM estimates be used to better inform irrigation scheduling decisions for lightly vegetated areas such as the turf or native roughs found on golf courses.

  18. Nanoparticle motion on the surface of drying droplets

    Science.gov (United States)

    Zhao, Mingfei; Yong, Xin

    2018-03-01

    Advances in solution-based printing and surface patterning techniques for additive manufacturing demand a clear understanding of particle dynamics in drying colloidal droplets and its relationship with deposit structure. Although the evaporation-driven deposition has been studied thoroughly for the particles dispersed in the bulk of the droplet, few investigations have focused on the particles strongly adsorbed to the droplet surface. We modeled the assembly and deposition of the surface-active particles in a drying sessile droplet with a pinned contact line by the multiphase lattice Boltzmann-Brownian dynamics method. The particle trajectory and its area density profile characterize the assembly dynamics and deposition pattern development during evaporation. While the bulk-dispersed particles continuously move to the contact line, forming the typical "coffee-ring" deposit, the interface-bound particles migrate first toward the apex and then to the contact line as the droplet dries out. To understand this unexpected behavior, we resolve the droplet velocity field both in the bulk and within the interfacial region. The simulation results agree well with the analytical solution for the Stokes flow inside an evaporating droplet. At different stages of evaporation, our study reveals that the competition between the tangential surface flow and the downward motion of the evaporating liquid-vapor interface governs the dynamics of the interface-bound particles. In particular, the interface displacement contributes to the particle motion toward the droplet apex in a short phase, while the outward advective flow prevails at the late stage of drying and carries the particles to the contact line. The final deposit of the surface-adsorbed particles exhibits a density enhancement at the center, in addition to a coffee ring. Despite its small influence on the final deposit in the present study, the distinct dynamics of surface-active particles due to the interfacial confinement

  19. The structure of the radiation balance on a sandy surface: case the Błędów desert, Silesian Upland

    Directory of Open Access Journals (Sweden)

    Caputa Zbigniew

    2016-06-01

    Full Text Available Comprehensive environmental studies taking under consideration the structure of the radiation balance during the vegetation growing seasons of 2001 and 2002 were carried out on the open sandy surface of the area called the Błędów ‘desert’ located on Silesian Upland. The research in each site covered the composition of plant species, their age and height, the condition of the substratum, the composition and structure of the soil and the meteorological conditions with elements of the radiation balance. The article presents some part of the research on meteorological elements and their impact on ecosystem. Special attention was devoted to radiation conditions on the open sandy surface in the context of the formation of BSC (biological soil crust. Having presumed that the values obtained on the grassy surface constituted 100%, the values of radiation reflection measured on the open sandy surface were 185% higher and the values of net longwave radiation were 105% higher in day time and 137% in night time. Values of net radiation of about 63% lower were observed on the sandy surface during a typical sunny summer day. It was found that a strong irradiation of the sandy surface (26 MJ·m–2d–1 creates extremely difficult conditions for the initiation of the process of ecosystem formation (including BSC or plant succession. The elements of the radiation balance, net radiation, albedo and temperature of the open sandy surface were represented quantitatively. The test surfaces were classified based on the value of the albedo: group I with low albedo values, up to 0.15 (spore-bearing plants on a dark surface, including BSC; group II with mean values of the albedo from 0.16 to 0.24 (spore-bearing plants and seed on a dark grey surface; and group III with high albedo values, above 0.25 (plants growing on bare or loose sands.

  20. Comparison and evaluation of gridded radiation products across northern Eurasia

    International Nuclear Information System (INIS)

    Troy, T J; Wood, E F

    2009-01-01

    Northern Eurasia is a region experiencing documented changes in temperature and large-scale streamflow, yet little attention has been focused on the large-scale energy budgets over the region. We compare station data and gridded radiation products from reanalysis and remote sensing to evaluate the radiative fluxes across northern Eurasia. On annual timescales, we find that the downward shortwave radiation products, with the exception of those of the NCEP/NCAR reanalysis, compare well with long-term station observations, but that this agreement breaks down with smaller timescales and for downward longwave and upward shortwave and longwave radiation. Of the six gridded products, the Surface Radiation Budget data set performs the best as compared to observations. Differences in radiative fluxes are on the order of 15-20 W m -2 on seasonal timescales, averaged across the region, with larger variations spatially and at smaller timescales. The resulting uncertainty in net radiation has implications for climate and hydrologic analyses that seek to understand changes in northern Eurasia climate and its hydrologic cycle.

  1. Meteorological data for four sites at surface-disruption features in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1985--1986

    International Nuclear Information System (INIS)

    Carman, R.L.

    1994-01-01

    Surface-disruption features, or craters, resulting from underground nuclear testing at the Nevada Test Site may increase the potential for ground-water recharge in an area that would normally produce little, if any, recharge. This report presents selected meteorological data resulting from a study of two surface-disruption features during May 1985 through June 1986. The data were collected at four adjacent sites in Yucca Flat, about 56 kilometers north of Mercury, Nevada. Three sites (one in each of two craters and one at an undisturbed site at the original land surface) were instrumented to collect meteorological data for calculating bare-soil evaporation. These data include (1) long-wave radiation, (2) short-wave radiation, (3) net radiation, (4) air temperature, and (5) soil surface temperature. Meteorological data also were collected at a weather station at an undisturbed site near the study craters. Data collected at this site include (1) air temperature, (2) relative humidity, (3) wind velocity, and (4) wind direction

  2. The Validation of the GEWEX SRB Surface Shortwave Flux Data Products Using BSRN Measurements: A Systematic Quality Control, Production and Application Approach

    Science.gov (United States)

    Zhang, Taiping; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Cox, Stephen J.; Mikovitz, J. Colleen; Hinkelman, Laura M.

    2013-01-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project has produced a 24.5-year continuous record of global shortwave and longwave radiation fluxes at TOA and the Earth's surface from satellite measurements. The time span of the data is from July 1983 to December 2007, and the spatial resolution is 11 latitude11 longitude. The inputs of the latest version (Release 3.0) include the GEOS Version 4.0.3 meteorological information and cloud properties derived from ISCCP DX data. The SRB products are available on 3-hourly, 3-hourly-monthly, daily and monthly time scales. To assess the quality of the product, we extensively validated the SRB data against 5969 site-months of groundbased measurements from 52 Baseline Surface Radiation Network (BSRN) stations. This paper describes first the characteristics of the BSRN data and the GEWEX SRB data, the methodology for quality control and processing of the shortwave BSRN data, and then the systematic SRB-BSRN comparisons. It is found that, except for occasional extreme outliers as seen in scatter plots, the satellite-based surface radiation data generally agree very well with BSRN measurements. Specifically, the bias/RMS for the daily and monthly mean shortwave fluxes are, respectively, -3.6/35.5 and -5.2/23.3W1 m2 under all-sky conditions.

  3. Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us po

    Science.gov (United States)

    2002-01-01

    Credit: Image courtesy Barbara Summey, NASA Goddard Visualization Analysis Lab, based upon data processed by Takmeng Wong, CERES Science Team, NASA Langley Research Center Satellite: Terra Sensor: CERES Image Date: 09-30-2001 VE Record ID: 11546 Description: Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us possible. But the energy cannot stay bound up in the Earth's environment forever. If it did then the Earth would be as hot as the Sun. Instead, as the surface and the atmosphere warm, they emit thermal longwave radiation, some of which escapes into space and allows the Earth to cool. This false-color image of the Earth was produced on September 30, 2001, by the Clouds and the Earth's Radiant Energy System (CERES) instrument flying aboard NASA's Terra spacecraft. The image shows where more or less heat, in the form of longwave radiation, is emanating from the top of Earth's atmosphere. As one can see in the image, the thermal radiation leaving the oceans is fairly uniform. The blue swaths across the central Pacific represent thick clouds, the tops of which are so high they are among the coldest places on Earth. In the American Southwest, which can be seen in the upper righthand corner of the globe, there is often little cloud cover to block outgoing radiation and relatively little water to absorb solar energy. Consequently, the amount of outgoing radiation in the American Southwest exceeds that of the oceans. Also, that region was experiencing an extreme heatwave when these data were acquired. Recently, NASA researchers discovered that incoming solar radiation and outgoing thermal radiation increased in the tropics from the 1980s to the 1990s. (Click to read the press release .) They believe that the reason for the unexpected increase has to do with an apparent change in circulation patterns around the globe, which effectively reduced the amount of water vapor and cloud cover in the upper reaches of the atmosphere

  4. A simulation model of distributions of radiational flux at leaf surfaces in crowns of fruit trees

    International Nuclear Information System (INIS)

    Yamamoto, T.

    1988-01-01

    A computer-model was constructed for estimating distributions with time of radiational fluxes at leaf surfaces throughout fruit tree canopies in which leaves did not distribute uniformely in three dimensional space. Several assumptions were set up to construct the model for approximation of using solid geometry. For irregular distribution of leaf area in three dimensional space data were used in the simulation as number of leaves per internal cubic bloc of a cubic grid (n-divided per side). Several main parameters used were peculiar to fruit species which contain parameters (λ, ν) of Beta function to calculate both probability density function of leaf area distribution with respect to inclination angle and leaf extinction coefficient for parallel beam by leaves parameters (A, R i ) to calculate stem extinction coefficient for parallel beam, and parameters (D i ) to calculate leaf extinction coefficient of downward transmission and downward reflection. With these data and parameters solid geometry and Lambert-Beer's law constituted this model

  5. Artificial Intelligence Mechanisms on Interactive Modified Simplex Method with Desirability Function for Optimising Surface Lapping Process

    Directory of Open Access Journals (Sweden)

    Pongchanun Luangpaiboon

    2014-01-01

    Full Text Available A study has been made to optimise the influential parameters of surface lapping process. Lapping time, lapping speed, downward pressure, and charging pressure were chosen from the preliminary studies as parameters to determine process performances in terms of material removal, lap width, and clamp force. The desirability functions of the-nominal-the-best were used to compromise multiple responses into the overall desirability function level or D response. The conventional modified simplex or Nelder-Mead simplex method and the interactive desirability function are performed to optimise online the parameter levels in order to maximise the D response. In order to determine the lapping process parameters effectively, this research then applies two powerful artificial intelligence optimisation mechanisms from harmony search and firefly algorithms. The recommended condition of (lapping time, lapping speed, downward pressure, and charging pressure at (33, 35, 6.0, and 5.0 has been verified by performing confirmation experiments. It showed that the D response level increased to 0.96. When compared with the current operating condition, there is a decrease of the material removal and lap width with the improved process performance indices of 2.01 and 1.14, respectively. Similarly, there is an increase of the clamp force with the improved process performance index of 1.58.

  6. Satellite-based climate data records of surface solar radiation from the CM SAF

    Science.gov (United States)

    Trentmann, Jörg; Cremer, Roswitha; Kothe, Steffen; Müller, Richard; Pfeifroth, Uwe

    2017-04-01

    radiation also the longwave surface radiation as well as surface albedo and numerous cloud properties are provided in CLARA. Here we provide an overview of the climate data records of the surface solar radiation and present the results of the quality assessment of both climate data records against available surface reference observations, e.g., from the BSRN and the GEBA data archive.

  7. Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

    Science.gov (United States)

    Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

    2013-01-01

    Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

  8. Experimental study of gas entrainment from surface swirl

    Energy Technology Data Exchange (ETDEWEB)

    Moudjed, B., E-mail: brahim.moudjed@cea.fr; Excoffon, J.; Riva, R.; Rossi, L., E-mail: lionel.rossi@cea.fr

    2016-12-15

    Gas entrainment from surface swirls is characterized using water experiments. A free surface shear flow is generated in an open channel flow. A suction nozzle is set at the bottom of the test section to induce a downward flow and provoke gas entrainment. An important originality of these experiments is the possibility to change the inlet condition so as to generate different turbulent shear flows. This is done by adding obstacles of different sizes and shapes at the end of a flat plate separating the inlet flow from a “stagnant” water area. Velocity fields and profiles, measured with the PIV technique, are provided both to describe the inlet conditions corresponding to various geometries and flow rates, and to characterize the temporal average shear flow generated within the centre part of the channel. Gas entrainment mappings are established from direct observations of the different flow configurations. These new results show that the threshold for the suction velocities required to entrain gas are similar for the configurations with small obstacles and the flat plate configuration triggering a standard shear flow. Increasing the size of the obstacles promotes gas entrainment and reduces the threshold values of the suction velocity to trigger gas entrainment. Shadowgraphy with image processing is used to present new results characterizing the geometrical properties of surface swirls and the quantity of gas entrained. Inlet configurations with obstacles generate larger surface swirls which move upstream from the suction nozzle centre whereas they are situated downstream with the flat plate configuration. Moreover, dimensionless power laws are found to be good approximations for the surface swirl width and the quantity of gas entrained. In addition to provide new insights about gas entrainment in analytical configurations relevant to Sodium cooled fast nuclear reactor, these results should provide different test cases for the validation of MCFD codes.

  9. The Relationship Between Surface Temperature Anomaly Time Series and those of OLR, Water Vapor, and Cloud Cover as Observed Using Nine Years of AIRS Version-5 Level-3 Products

    Science.gov (United States)

    Susskind, Joel; Molnar, Gyula; Iredell, Lena

    2011-01-01

    Outline: (1) Comparison of AIRS and CERES anomaly time series of outgoing longwave radiation (OLR) and OLR(sub CLR), i.e. Clear Sky OLR (2) Explanation of recent decreases in global and tropical mean values of OLR (3) AIRS "Short-term" Longwave Cloud Radiative Feedback -- A new product

  10. Cryogenic Selective Surfaces

    Data.gov (United States)

    National Aeronautics and Space Administration — Selective surfaces have wavelength dependent emissivity/absorption. These surfaces can be designed to reflect solar radiation, while maximizing infrared emittance,...

  11. Characterization of solid surfaces

    National Research Council Canada - National Science Library

    Kane, Philip F; Larrabee, Graydon B

    1974-01-01

    .... A comprehensive review of surface analysis, this important volume surveys both principles and techniques of surface characterization, describes instrumentation, and suggests the course of future research...

  12. Long-wave Infrared Detectors for the Planetary Infrared Spectrometers

    Data.gov (United States)

    National Aeronautics and Space Administration — Understanding the role of primitive bodies as building blocks for planets and life are key targets for space exploration. Chemical and mineralogical...

  13. Silicon waveguided components for the long-wave infrared region

    Science.gov (United States)

    Soref, Richard A.; Emelett, Stephen J.; Buchwald, Walter R.

    2006-10-01

    We propose that the operational wavelength of waveguided Si-based photonic integrated circuits and optoelectronic integrated circuits can be extended beyond the 1.55 µm telecom range into the wide infrared from 1.55 to 100 µm. The Si rib-membrane waveguide offers low-loss transmission from 1.2 to 6 µm and from 24 to 100 µm. This waveguide, which is compatible with Si microelectronics manufacturing, is constructed from silicon-on-insulator by etching away the oxide locally beneath the rib. Alternatively, low-loss waveguiding from 1.9 to 14.7 µm is assured by employing a crystal Ge rib grown directly upon the Si substrate. The Si-based hollow-core waveguide is an excellent device that minimizes loss due to silicon's 6-24 µm multi-phonon absorption. Here the rectangular air-filled core is surrounded by SiGe/Si multi-layer anti-resonant or Bragg claddings. The hollow channel offers less than 1.7 dB cm-1 loss from 1.2 to 100 µm. .

  14. Long-wave forcing for regional atmospheric modelling

    Energy Technology Data Exchange (ETDEWEB)

    Storch, H. von; Langenberg, H.; Feser, F. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

    1999-07-01

    A new method, named 'spectral nudging', of linking a regional model to the driving large-scale model simulated or analyzed by a global model is proposed and tested. Spectral nudging is based on the idea that regional-scale climate statistics are conditioned by the interplay between continental-scale atmospheric conditions and such regional features as marginal seas and mountain ranges. Following this 'downscaling' idea, the regional model is forced to satisfy not only boundary conditions, possibly in a boundary sponge region, but also large-scale flow conditions inside the integration area. We demonstrate that spectral nudging succeeds in keeping the simulated state close to the driving state at large scales, while generating smaller-scale features. We also show that the standard boundary forcing technique in current use allows the regional model to develop internal states conflicting with the large-scale state. It is concluded that spectral nudging may be seen as a suboptimal and indirect data assimilation technique. (orig.) [German] Eine neue Methode, genannt 'spektrales nudging', ein Regionalmodell an das durch ein Globalmodell simulierte grossskalige Antriebsfeld zu koppeln, wird vorgestellt und getestet. Das spektrale nudging basiert auf der Annahme, dass regionale Klimastatistik durch die Wechselwirkung zwischen dem kontinental-skaligen atmosphaerischen Zustand und regionalen Gegebenheiten, wie kleinere Seen und Gebirgszuege, bestimmt wird. Demnach muss das Regionalmodell nicht nur die Randbedingungen erfuellen, sondern auch die grossskaligen Zustaende innerhalb des Integrationsgebietes wiedergeben koennen. Wir zeigen, dass durch das spektrale nudging der grossskalige modellierte Zustand nahe an dem des Antriebsfeldes liegt, ohne die Modellierung regionaler Phaenomene zu beeintraechtigen. Ausserdem zeigen wir, dass das Regionalmodell durch die zur Zeit benutzte Antriebstechnik ueber den Modellrand interne Felder produzieren kann, die zu dem grossskaligen Zustand im Widerspruch stehen. Wird schliessen daraus, dass das spektrale nudging als eine suboptimale, indirekte Datenassimilierungsmethode angesehen werden kann. (orig.)

  15. Open algebraic surfaces

    CERN Document Server

    Miyanishi, Masayoshi

    2000-01-01

    Open algebraic surfaces are a synonym for algebraic surfaces that are not necessarily complete. An open algebraic surface is understood as a Zariski open set of a projective algebraic surface. There is a long history of research on projective algebraic surfaces, and there exists a beautiful Enriques-Kodaira classification of such surfaces. The research accumulated by Ramanujan, Abhyankar, Moh, and Nagata and others has established a classification theory of open algebraic surfaces comparable to the Enriques-Kodaira theory. This research provides powerful methods to study the geometry and topology of open algebraic surfaces. The theory of open algebraic surfaces is applicable not only to algebraic geometry, but also to other fields, such as commutative algebra, invariant theory, and singularities. This book contains a comprehensive account of the theory of open algebraic surfaces, as well as several applications, in particular to the study of affine surfaces. Prerequisite to understanding the text is a basic b...

  16. Characterization of as-grown and adsorbate-covered N-polar InN surfaces using in situ photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Eisenhardt, Anja; Himmerlich, Marcel; Krischok, Stefan

    2012-01-01

    The surface electronic properties and adsorption behaviour of as-grown and oxidized N-polar InN films are characterized by photoelectron spectroscopy (XPS, UPS). The epitaxial growth of the InN layers was performed by plasma-assisted molecular beam epitaxy on GaN/6H-SiC(000-1). After growth and in situ characterization the InN surfaces were exposed to molecular oxygen to evaluate the adsorption behaviour of O 2 on N-polar InN and to study its impact on the surface electronic properties of the III-nitride material. The results are compared with studies on In-polar InN on GaN/sapphire templates. The as-grown N-polar InN surface exhibits a pronounced surface state at a binding energy of ∝1.6 eV. The valence band minimum lies about 0.8-1.0 eV below the surface Fermi level. Additionally, the XPS core level binding energies for InN(000-1) are reduced compared to InN(0001) films, indicating different surface band bending for clean N-polar and In-polar InN, respectively. The interaction of molecular oxygen with the InN(000-1) surface leads to a downward band bending by 0.1 eV compared to the initial state. Additional adsorption of species from the residual gas of the UHV chamber increases the surface downward band bending. Furthermore two pronounced oxygen related states with an energy distance of ∝5 eV could be detected in the valence band region. The adsorbed oxygen results in an additional component in the N1s core level spectra, which is interpreted as formation of NO x bonds. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. An assessment of the land surface emissivity in the 8 - 12 micrometer window determined from ASTER and MODIS data

    Science.gov (United States)

    Schmugge, T.; Hulley, G.; Hook, S.

    2009-04-01

    The land surface emissivity is often overlooked when considering surface properties that effect the energy balance. However, knowledge of the emissivity in the window region is important for determining the longwave radiation balance and its subsequent effect on surface temperature. The net longwave radiation (NLR) is strongly affected by the difference between the temperature of the emitting surface and the sky brightness temperature, this difference will be the greatest in the window region. Outside the window region any changes in the emitted radiation by emissivity variability are mostly compensated for by changes in the reflected sky brightness. The emissivity variability is typically greatest in arid regions where the exposed soil and rock surfaces display the widest range of emissivity. For example, the dune regions of North Africa have emissivities of 0.7 or less in the 8 to 9 micrometer wavelength band due to the quartz sands of the region, which can produce changes in NLR of more than 10 w/m*m compared to assuming a constant emissivity. The errors in retrievals of atmospheric temperature and moisture profiles from hyperspectral infrared radiances, such as those from the Atmospheric Infrared Sounder (AIRS) on the NASA Aqua satellite result from using constant or inaccurate surface emissivities, particularly over arid and semi-arid regions here the variation in emissivity is large, both spatially and spectrally. The multispectral thermal infrared data obtained from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer and MODerate resolution Imaging Spectrometer (MODIS) sensors on NASA's Terra satellite have been shown to be of good quality and provide a unique new tool for studying the emissivity of the land surface. ASTER has 5 channels in the 8 to 12 micrometer waveband with 90 m spatial resolution, when the data are combined with the Temperature Emissivity Separation (TES) algorithm the surface emissivity over this wavelength region

  18. Comparison between the land surface response of the ECMWF model and the FIFE-1987 data

    Science.gov (United States)

    Betts, Alan K.; Ball, John H.; Beljaars, Anton C. M.

    1993-01-01

    An averaged time series for the surface data for the 15 x 15 km FIFE site was prepared for the summer of 1987. Comparisons with 48-hr forecasts from the ECMWF model for extended periods in July, August, and October 1987 identified model errors in the incoming SW radiation in clear skies, the ground heat flux, the formulation of surface evaporation, the soil-moisture model, and the entrainment at boundary-layer top. The model clear-sky SW flux is too high at the surface by 5-10 percent. The ground heat flux is too large by a factor of 2 to 3 because of the large thermal capacity of the first soil layer (which is 7 cm thick), and a time truncation error. The surface evaporation was near zero in October 1987, rather than of order 70 W/sq m at noon. The surface evaporation falls too rapidly after rainfall, with a time-scale of a few days rather than the 7-10 d (or more) of the observations. On time-scales of more than a few days the specified 'climate layer' soil moisture, rather than the storage of precipitation, has a large control on the evapotranspiration. The boundary-layer-top entrainment is too low. This results in a moist bias in the boundary-layer mixing ratio of order 2 g/Kg in forecasts from an experimental analysis with nearly realistic surface fluxes; this because there is insufficient downward mixing of dry air.

  19. Early stages of Cs adsorption mechanism for GaAs nanowire surface

    Science.gov (United States)

    Diao, Yu; Liu, Lei; Xia, Sihao; Feng, Shu

    2018-03-01

    In this study, the adsorption mechanism of Cs adatoms on the (100) surface of GaAs nanowire with [0001] growth direction is investigated utilizing first principles method based on density function theory. The adsorption energy, work function, atomic structure and electronic property of clean surface and Cs-covered surfaces with different coverage are discussed. Results show that when only one Cs is adsorbed on the surface, the most favorable adsorption site is BGa-As. With increasing Cs coverage, work function gradually decreases and gets its minimum at 0.75 ML, then rises slightly when Cs coverage comes to 1 ML, indicating the existence of 'Cs-kill' phenomenon. According to further analysis, Cs activation process can effectively reduce the work function due to the formation of a downward band bending region and surface dipole moment directing from Cs adatom to the surface. As Cs coverage increases, the conduction band minimum and valence band maximum both shift towards lower energy side, contributed by the orbital hybridization between Cs-5s, Cs-5p states and Ga-4p, As-4s, As-4p states near Fermi level. The theoretical calculations and analysis in this study can improve the Cs activation technology for negative electron affinity optoelectronic devices based on GaAs nanowires, and also provide a reference for the further Cs/O or Cs/NF3 activation process.

  20. Spatial distribution of potential near surface moisture flux at Yucca Mountain

    International Nuclear Information System (INIS)

    Flint, A.L.; Flint, L.E.

    1994-01-01

    An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity, moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages

  1. Spatial distribution of potential near surface moisture flux at Yucca Mountain

    International Nuclear Information System (INIS)

    Flint, A.L.; Flint, L.E.

    1994-01-01

    An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages

  2. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  3. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

    Science.gov (United States)

    McFarlane, S. A.; Gaustad, K. L.; Mlawer, E. J.; Long, C. N.; Delamere, J.

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  4. A study of the mechanisms causing surface defects on sidewalls during Si etching for TSV (through Si via)

    International Nuclear Information System (INIS)

    Choi, Jae Woong; Loh, Woon Leng; Praveen, Sampath Kumar; Murphy, Ramana; Swee, Eugene Tan Kiat

    2013-01-01

    In this paper we report three mechanisms causing surface defects on Si sidewalls during Si etching for TSV. The first mechanism causing surface defects was a downward surface-defect formation due to the participation of the residual polymerizing gas in the transition periods between passivation steps and etch steps. The second mechanism was an upward surface-defect formation due to etchant attacking the interface between the Si and the sidewall polymer. Although the sidewall polymer was thick enough to protect the Si surface, it was not possible to avoid surface defects if the etch step was not switched to the following passivation step in time. The third mechanism was a sponge-like surface-defect formation caused by either poor polymer depositions or voids inside the sidewall polymer. The sponge-like surface defects were formed by Si isotropic etching through the weak points of the sidewall polymer. All three surface defects were considered as the major factors on TSV integration and packaging reliability issues. (paper)

  5. Contrasting responses of urban and rural surface energy budgets to heat waves explain synergies between urban heat islands and heat waves

    International Nuclear Information System (INIS)

    Li, Dan; Sun, Ting; Liu, Maofeng; Yang, Long; Wang, Linlin; Gao, Zhiqiu

    2015-01-01

    Heat waves (HWs) are projected to become more frequent and last longer over most land areas in the late 21st century, which raises serious public health concerns. Urban residents face higher health risks due to synergies between HWs and urban heat islands (UHIs) (i.e., UHIs are higher under HW conditions). However, the responses of urban and rural surface energy budgets to HWs are still largely unknown. This study analyzes observations from two flux towers in Beijing, China and reveals significant differences between the responses of urban and rural (cropland) ecosystems to HWs. It is found that UHIs increase significantly during HWs, especially during the nighttime, implying synergies between HWs and UHIs. Results indicate that the urban site receives more incoming shortwave radiation and longwave radiation due to HWs as compared to the rural site, resulting in a larger radiative energy input into the urban surface energy budget. Changes in turbulent heat fluxes also diverge strongly for the urban site and the rural site: latent heat fluxes increase more significantly at the rural site due to abundant available water, while sensible heat fluxes and possibly heat storage increase more at the urban site. These comparisons suggest that the contrasting responses of urban and rural surface energy budgets to HWs are responsible for the synergies between HWs and UHIs. As a result, urban mitigation and adaption strategies such as the use of green roofs and white roofs are needed in order to mitigate the impact of these synergies. (letter)

  6. Surfaces with Natural Ridges

    DEFF Research Database (Denmark)

    Brander, David; Markvorsen, Steen

    2015-01-01

    We discuss surfaces with singularities, both in mathematics and in the real world. For many types of mathematical surface, singularities are natural and can be regarded as part of the surface. The most emblematic example is that of surfaces of constant negative Gauss curvature, all of which...

  7. Approximation by Cylinder Surfaces

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1997-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...

  8. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail; Pottmann, Helmut; Grohs, Philipp

    2011-01-01

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ

  9. Potential sea salt aerosol sources from frost flowers in the pan-Arctic region

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Li [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Now at Department of Earth System Science, University of California, Irvine California USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Burrows, Susannah M. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

    2016-09-23

    In order to better represent observed wintertime aerosol concentrations at Barrow, Alaska, we implemented an observationally-based parameterization for estimating sea salt production from frost flowers in the Community Earth System Model (CESM). In this work, we evaluate the potential influence of this sea salt source on the pan-Arctic (60ºN-90ºN) climate. Results show that frost flower salt emissions substantially increase the modeled surface sea salt aerosol concentration in the winter months when new sea ice and frost flowers are present. The parameterization reproduces both the magnitude and seasonal variation of the observed submicron sea salt aerosol concentration at surface in Barrow during winter much better than the standard CESM simulation without a frost-flower salt particle source. Adding these frost flower salt particle emissions increases aerosol optical depth by 10% and results in a small cooling at surface. The increase in salt particle mass concentrations of a factor of 8 provides nearly two times the cloud condensation nuclei concentration, as well as 10% increases in cloud droplet number and 40% increases in liquid water content near coastal regions adjacent to continents. These cloud changes reduce longwave cloud forcing by 3% and cause a small surface warming, increasing the downward longwave flux at the surface by 2 W m-2 in the pan-Arctic under the present-day climate.

  10. Possible influence of long-term sea surface temperature anomalies in the tropical Pacific on global zone

    Energy Technology Data Exchange (ETDEWEB)

    Komhyr, W D; Oltmans, S J; Grass, R D [Atmospheric Administration Climate Monitoring and Diagnostics Lab., Boulder, CO (USA); Leonard, R K [Colorado Univ., Boulder, CO (USA)

    1991-01-01

    A significant negative correlation exists between summer sea surface temperatures (SSTs) in the east equatorial Pacific and late-October south pole total ozone values. SSTs in the eastern equatorial Pacific were anomalously warmer during 1976-1987 compared with 1962-1975. QBO (quasi-biennial oscillation) easterly winds in the equatorial Pacific stratosphere were generally stronger after 1975. Before the early-to-mid 1970s the trend in global ozone was generally upward, but then turned downward. Total ozone at Hawaii and Samoa, which had been decreasing during 1976-1987, showed recovery to mid-1970s values in 1988-1989 following a drop in SSTs in the eastern equatorial Pacific to low values last observed there prior to 1976. During late October 1988, total south pole ozone, which had decreased from ca 280 Dobson units (DU) before 1980 to 140 DU in 1987, suddenly recovered to 250 DU, though substantial ozone depletion by heterogeneous photochemical processes involving polar stratospheric clouds was still evident in the south pole ozone vertical profiles. These observations suggest that the downward trend in ozone observed over the globe in recent years may have been at least partly meteorologically induced, possibly via modulation by the warmer tropical Pacific ocean waters of QBO easterly winds at the equator, of Hadley Cell circulation, or other factors. A cursory analysis of geostrophic wind flow around the Baffin Island low suggests a meteorological influence on the observed downward trend in ozone over North America during the past decade. Because ozone has a lifetime that varies from years to minutes, changes in atmospheric dynamics have a potential to not only redistribute ozone over the globe but also to change global ozone abundance. 47 refs., 5 figs., 1 tab.

  11. Surface Topography Hinders Bacterial Surface Motility.

    Science.gov (United States)

    Chang, Yow-Ren; Weeks, Eric R; Ducker, William A

    2018-03-21

    We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.

  12. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD</