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Sample records for single-scattering albedo ssa

  1. Parameterization of single-scattering albedo (SSA) and absorption Ångström exponent (AAE) with EC / OC for aerosol emissions from biomass burning

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    Pokhrel, Rudra P.; Wagner, Nick L.; Langridge, Justin M.; Lack, Daniel A.; Jayarathne, Thilina; Stone, Elizabeth A.; Stockwell, Chelsea E.; Yokelson, Robert J.; Murphy, Shane M.

    2016-08-01

    Single-scattering albedo (SSA) and absorption Ångström exponent (AAE) are two critical parameters in determining the impact of absorbing aerosol on the Earth's radiative balance. Aerosol emitted by biomass burning represent a significant fraction of absorbing aerosol globally, but it remains difficult to accurately predict SSA and AAE for biomass burning aerosol. Black carbon (BC), brown carbon (BrC), and non-absorbing coatings all make substantial contributions to the absorption coefficient of biomass burning aerosol. SSA and AAE cannot be directly predicted based on fuel type because they depend strongly on burn conditions. It has been suggested that SSA can be effectively parameterized via the modified combustion efficiency (MCE) of a biomass burning event and that this would be useful because emission factors for CO and CO2, from which MCE can be calculated, are available for a large number of fuels. Here we demonstrate, with data from the FLAME-4 experiment, that for a wide variety of globally relevant biomass fuels, over a range of combustion conditions, parameterizations of SSA and AAE based on the elemental carbon (EC) to organic carbon (OC) mass ratio are quantitatively superior to parameterizations based on MCE. We show that the EC / OC ratio and the ratio of EC / (EC + OC) both have significantly better correlations with SSA than MCE. Furthermore, the relationship of EC / (EC + OC) with SSA is linear. These improved parameterizations are significant because, similar to MCE, emission factors for EC (or black carbon) and OC are available for a wide range of biomass fuels. Fitting SSA with MCE yields correlation coefficients (Pearson's r) of ˜ 0.65 at the visible wavelengths of 405, 532, and 660 nm while fitting SSA with EC / OC or EC / (EC + OC) yields a Pearson's r of 0.94-0.97 at these same wavelengths. The strong correlation coefficient at 405 nm (r = 0.97) suggests that parameterizations based on EC / OC or EC / (EC + OC) have good predictive

  2. Aerosol single scattering albedo estimated across China from a combination of ground and satellite measurements

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    Kwon Ho Lee; Zhanqing Li; Man Sing Wong; Jinyuan Xin; Wang Yuesi; Wei Min Hao; Fengsheng Zhao

    2007-01-01

    Single scattering albedo (SSA) governs the strength of aerosols in absorbing solar radiation, but few methods are available to directly measure this important quantity. There currently exist many ground-based measurements of spectral transmittance from which aerosol optical thickness (AOT) are retrieved under clear sky conditions. Reflected radiances at the top of the...

  3. Seasonal Variability of Aerosol Single Scattering Albedo at Biomass Burning Sites in Southern Africa and Amazonia

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Mukelabai, M. M.; Dubovik, O.; Smirnov, A.; Schafer, J. S.; Slutsker, I.

    2002-05-01

    Monitoring of the optical properties of primarily biomass burning aerosols in Mongu, Zambia was initiated in 1995, when an AERONET sun/sky radiometer site was established at the Mongu airport. For the biomass burning season months (July-November), we present monthly means of aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals utilizing the algorithm of Dubovik and King (2000). The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from July (0.845) to October (0.93). The slope of the spectral dependence of aerosol single scattering albedo with wavelength decreased as SSA increased from July to October. However, there was no significant change in particle size in either the dominant accumulation or secondary coarse modes during these months. Similarly, seasonal SSA retrievals for Etosha Pan, Namibia also show increasing values through the burning season in 2000. We also analyze the seasonality of SSA for sites in biomass burning regions of Amazonia. We show maps of satellite detected fire counts which indicate that the regions of primary biomass burning shift significantly from July to October. Possible reasons for the seasonal changes in observed SSA include differences in aging to due transport speed and distance from source regions, differences in biomass fuel types in different regions (fraction of woody biomass versus grasses), and differences in fuel moisture content (October is the beginning of the rainy season on both continents).

  4. Using Single-Scattering Albedo Spectral Curvature to Characterize East Asian Aerosol Mixtures

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    Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

    2015-01-01

    Spectral dependence of aerosol single-scattering albedo (SSA) has been used to infer aerosol composition. In particular, aerosol mixtures dominated by dust absorption will have monotonically increasing SSA with wavelength while that dominated by black carbon absorption has monotonically decreasing SSA spectra. However, by analyzing SSA measured at four wavelengths, 440, 675, 870, and 1020 nm from the Aerosol Robotic Network data set, we find that the SSA spectra over East Asia are frequently peaked at 675 nm. In these cases, we suggest that SSA spectral curvature, defined as the negative of the second derivative of SSA as a function of wavelength, can provide additional information on the composition of these aerosol mixtures. Aerosol SSA spectral curvatures for East Asia during fall and winter are considerably larger than those found in places primarily dominated by biomass burning or dust aerosols. SSA curvature is found to increase as the SSA magnitude decreases. The curvature increases with coarse mode fraction (CMF) to a CMF value of about 0.4, then slightly decreases or remains constant at larger CMF. Mie calculations further verify that the strongest SSA curvature occurs at approx. 40% dust fraction, with 10% scattering aerosol fraction. The nonmonotonic SSA spectral dependence is likely associated with enhanced absorption in the shortwave by dust, absorption by black carbon at longer wavelengths, and also the flattened absorption optical depth spectral dependence due to the increased particle size.

  5. Effective single scattering albedo estimation using regional climate model

    CSIR Research Space (South Africa)

    Tesfaye, M

    2011-09-01

    Full Text Available In this study, by modifying the optical parameterization of Regional Climate model (RegCM), the authors have computed and compared the Effective Single-Scattering Albedo (ESSA) which is a representative of VIS spectral region. The arid, semi...

  6. Seasonal Trend of Aerosol Single Scattering Albedo at Biomass Burning Sites in Southern Africa

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Ward, D.; Mukelabai, M. M.; Piketh, S.; Hyer, E. J.; Dubovik, O.; Sinyuk, A.; Schafer, J. S.; Giles, D. M.; Smirnov, A.; Slutsker, I.

    2011-12-01

    A database of the optical properties of primarily biomass burning aerosols in Mongu, Zambia from multi-year monitoring at an AERONET sun-sky radiometer site was examined. For the biomass burning season months (July-November), we investigate the aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals utilizing the algorithm of Dubovik and King (2000). The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from ~0.84 in July to ~0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Angstrom Exponent (440-870 nm; r2=0.02). A significant downward seasonal trend in imaginary refractive index (r2=0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, seasonal SSA retrievals for both the Etosha Pan, Namibia and Skukuza, South Africa AERONET sites also show increasing single scattering albedo values through the burning season. We show maps of satellite detected fire counts, which indicate that the regions of primary biomass burning in southern Africa shift significantly from July to October. Possible reasons for the seasonal changes in observed SSA include differences in biomass fuel types in different regions and seasons (fraction of woody biomass versus grasses), agricultural practices (Chitemene: in which woody fuels are burned at the end of the dry season), differences in fuel moisture content (as mid-October is the typical beginning of the rainy season) and differences in aging due to transport speed and distance from varying source regions. We also analyze the seasonality of SSA for sites in biomass burning regions of southern Amazonia, where no significant seasonal trend in SSA was detected.

  7. Retrievals and uncertainty analysis of aerosol single scattering albedo from MFRSR measurements

    International Nuclear Information System (INIS)

    Yin, Bangsheng; Min, Qilong; Joseph, Everette

    2015-01-01

    Aerosol single scattering albedo (SSA) can be retrieved from the ratio of diffuse horizontal and direct normal fluxes measured from multifilter rotating shadowband radiometer (MFRSR). In this study, the measurement channels at 415 nm and 870 nm are selected for aerosol optical depth (AOD) and Angstrom coefficient retrievals, and the measurements at 415 nm are used for aerosol SSA retrievals with the constraint of retrieved Angstrom coefficient. We extensively assessed various issues impacting on the accuracy of SSA retrieval from measurements to input parameters and assumptions. For cloud-free days with mean aerosol loading of 0.13–0.60, our sensitivity study indicated that: (1) 1% calibration uncertainty can result in 0.8–3.7% changes in retrieved SSA; (2) without considering the cosine respond correction and/or forward scattering correction will result in underestimation of 1.1–3.3% and/or 0.73% in retrieved SSA; (3) an overestimation of 0.1 in asymmetry factor can result in an underestimation of 2.54–3.4% in retrieved SSA; (4) for small aerosol loading (e.g., 0.13), the uncertainty associated with the choice of Rayleigh optical depth value can result in non-negligible change in retrieved SSA (e.g., 0.015); (5) an uncertainty of 0.05 for surface albedo can result in changes of 1.49–5.4% in retrieved SSA. We applied the retrieval algorithm to the MFRSR measurements at the Atmospheric Radiation Measurements (ARM) Southern Great Plains (SGP) site. The retrieved results of AOD, Angstrom coefficient, and SSA are basically consistent with other independent measurements from co-located instruments at the site. - Highlights: • Aerosol SSA is derived from MFRSR measured diffuse to direct normal irradiance ratio. • We extensively assessed various issues impacting on the accuracy of SSA retrieval. • The issues are mainly from measurements and model input parameters and assumptions. • We applied the retrieval algorithm to the MFRSR measurements at ARM SGP

  8. The effect of the global UV irradiance measurement accuracy on the single scattering albedo retrieval

    Directory of Open Access Journals (Sweden)

    S. Kazadzis

    2010-08-01

    Full Text Available The possibility of measuring aerosol optical absorption properties in the UV spectral range such as single scattering albedo (SSA, using remote sensing techniques, is currently an open scientific issue. We investigate the limitations on calculating column average SSA using a combination of global UV spectral measurements (that are comon in various UV monitoring stations worldwide with radiative transfer modeling. To point out the difficulties in such a retrieval we have used the travelling reference spectroradiometer QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe results from 27 visits to UV monitoring stations around Europe. We have used the QASUME instrument as relative reference, analyzing absolute differences and also temporal and spectral deviations of UV irraidances, that are used as basic input for the SSA retrieval.

    The results comparing the mean SSA derived by all instruments, measuring synchronous UV spectra, showed that 5 were within ± 0.02 difference from the SSA calculated from the QASUME instrument, while 17 were within ± 0.04, for the Solar zenith angle of 60 degrees. As for the uncertainty that has been calculated using the 2σ standard deviation of the spectral measurements, a mean 0.072 and 0.10 (2σ uncertainties have been calculated for 60° and 30°, respectively. Based on the fact that additional uncertainties would be introduced in the SSA retrieval from AOD model input accuracy, assymetry parameter assumptions, we show that only very few instrumnents could be able to detect long term SSA changes. However, such measurements/results ar useful in order to retrieve SSA at UV wavelengths, a product needed for various applications such as, inputs for modeling radiative forcing studies and satellite retrieval algorithms.

  9. On Spectral Invariance of Single Scattering Albedo for Weakly Absorbing Wavelengths

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    Marshak, Alexander

    2012-01-01

    The single scattering albedo omega (sub 0 lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength A and droplet size r. In this presentation we will show that for water droplets at weakly absorbing wavelengths, the ratio omega (sub 0 lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo omega (sub 0 lambda) via one known spectrum omega (sub 0 lambda)(r(sub o)). We will provide a simple physical explanation of the discovered relationship. In addition to water droplets, similar linear relationships were found for the single scattering albedo of non-spherical ice crystals. The single scattering albedo $\\omega _ {0\\lambda }$ in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, and thus the single scattering albedo, are functions of wavelength $\\lambda $ and droplet size $r$. We show that for water droplets at weakly absorbing wavelengths, the ratio $\\omega _ {0\\lambda } (r)$/$\\omega _ {0\\lambda } (r_{0})$ of two single scattering albedo spectra for two different droplet sizes is a linear function of $\\omega _{0\\lambda }(r)$. The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo $\\omega_{0\\lambda }(r)$ via one known spectrum $\\omega_{0\\lambda }(r_{0})$. We provide a simple physical explanation of the discovered relationship. Similar linear relationships characterize the single scattering albedo of non-spherical ice crystals.

  10. Aerosol single-scattering albedo retrieval over North Africa using critical reflectance

    Science.gov (United States)

    Wells, Kelley C.

    The sign and magnitude of the aerosol radiative forcing over bright surfaces is highly dependent on the absorbing properties of the aerosol. Thus, the determination of aerosol forcing over desert regions requires accurate information about the aerosol single-scattering albedo (SSA). However, the brightness of desert surfaces complicates the retrieval of aerosol optical properties using passive space-based measurements. The aerosol critical reflectance is one parameter that can be used to relate top-of-atmosphere (TOA) reflectance changes over land to the aerosol absorption properties, without knowledge of the underlying surface properties or aerosol loading. Physically, the parameter represents the TOA reflectance at which increased aerosol scattering due to increased aerosol loading is balanced by increased absorption of the surface contribution to the TOA reflectance. It can be derived by comparing two satellite images with different aerosol loading, assuming that the surface reflectance and background aerosol are similar between the two days. In this work, we explore the utility of the critical reflectance method for routine monitoring of spectral aerosol absorption from space over North Africa, a region that is predominantly impacted by absorbing dust and biomass burning aerosol. We derive the critical reflectance from Moderate Resolution Spectroradiometer (MODIS) Level 1B reflectances in the vicinity of two Aerosol Robotic Network (AERONET) stations: Tamanrasset, a site in the Algerian Sahara, and Banizoumbou, a Sahelian site in Niger. We examine the sensitivity of the critical reflectance parameter to aerosol physical and optical properties, as well as solar and viewing geometry, using the Santa Barbara DISORT Radiative Transfer (SBDART) model, and apply our findings to retrieve SSA from the MODIS critical reflectance values. We compare our results to AERONET-retrieved estimates, as well as to measurements of the TOA albedo and surface fluxes from the

  11. Aerosol optical properties at Lampedusa (Central Mediterranean. 2. Determination of single scattering albedo at two wavelengths for different aerosol types

    Directory of Open Access Journals (Sweden)

    D. Meloni

    2006-01-01

    Full Text Available Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR at the island of Lampedusa (35.5° N, 12.6° E, in the Central Mediterranean, in the period July 2001–September 2003. In a companion paper (Pace et al., 2006 the aerosol optical depth (AOD and Ångström exponent were used together with airmass backward trajectories to identify and classify different aerosol types. The MFRSR diffuse-to-direct ratio (DDR at 415.6 nm and 868.7 nm for aerosol classified as 'biomass burning-urban/industrial', originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the aerosol single scattering albedo (SSA. A detailed radiative transfer model is initialised with the measured aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g, and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of <0.04 at 415.6 nm, and <0.06 at 868.7 nm; finally, an increase of the assumed surface albedo of 0.05 causes very small changes (0.01–0.02 in the retrieved SSA. The calculations show that the SSA of desert dust (DD increases with wavelength, from 0.81±0.05 at 415.6 nm to 0.94±0.05 at 868.7 nm; on the contrary, the SSA of urban/industrial (UN aerosols decreases from 0.96±0.02 at 415.6 nm to 0.87±0.07 at 868.7 nm; the SSA of biomass burning (BB particles is 0.82±0.04 at 415.6 nm and 0.80±0.05 at 868.7 nm. Episodes of UN aerosols occur usually in June and July; long lasting BB aerosol episodes

  12. Wavelength dependence of Ångström exponent and single scattering albedo observed by skyradiometer in Seoul, Korea

    Science.gov (United States)

    Koo, Ja-Ho; Kim, Jhoon; Lee, Jaehwa; Eck, Thomas F.; Lee, Yun Gon; Park, Sang Seo; Kim, Mijin; Jung, Ukkyo; Yoon, Jongmin; Mok, Jungbin; Cho, Hi-Ku

    2016-11-01

    Absorption and scattering characteristics of various aerosol events are investigated using 2-years of measurements from a skyradiometer at Yonsei University in Seoul, Korea. Both transported dust and anthropogenic aerosols are observed at distinct geo-location of Seoul, a megacity located a few thousand kilometers away from dust source regions in China. We focus on the wavelength dependence of Ångström exponent (AE) and single scattering albedo (SSA), showing the characteristics of regional aerosols. The correlation between spectral SSAs and AEs calculated using different wavelength pairs generally indicates relatively weak absorption of fine-mode aerosols (urban pollution and/or biomass burning) and strong absorption of coarse-mode aerosols (desert dust) at this location. AE ratio (AER), a ratio of AEs calculated using wavelength pair between shorter (340-675 nm) and longer wavelength pair (675-1020 nm) correlates differently with SSA according to the dominant size of local aerosols. Correlations between SSA and AER show strong absorption of aerosols for AER 2.0. Based on the seasonal pattern of wavelength dependence of AER and SSA, this correlation difference looks to reveal the separated characteristics of transported dust and anthropogenic particles from urban pollution respectively. The seasonal characteristics of AER and SSAs also show that the skyradiometer measurement with multiple wavelengths may be able to detect the water soluble brown carbon, one of the important secondary organic aerosols in the summertime atmospheric composition.

  13. Spatial distribution of mineral dust single scattering albedo based on DREAM model

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    Kuzmanoski, Maja; Ničković, Slobodan; Ilić, Luka

    2016-04-01

    Mineral dust comprises a significant part of global aerosol burden. There is a large uncertainty in estimating role of dust in Earth's climate system, partly due to poor characterization of its optical properties. Single scattering albedo is one of key optical properties determining radiative effects of dust particles. While it depends on dust particle sizes, it is also strongly influenced by dust mineral composition, particularly the content of light-absorbing iron oxides and the mixing state (external or internal). However, an assumption of uniform dust composition is typically used in models. To better represent single scattering albedo in dust atmospheric models, required to increase accuracy of dust radiative effect estimates, it is necessary to include information on particle mineral content. In this study, we present the spatial distribution of dust single scattering albedo based on the Dust Regional Atmospheric Model (DREAM) with incorporated particle mineral composition. The domain of the model covers Northern Africa, Middle East and the European continent, with horizontal resolution set to 1/5°. It uses eight particle size bins within the 0.1-10 μm radius range. Focusing on dust episode of June 2010, we analyze dust single scattering albedo spatial distribution over the model domain, based on particle sizes and mineral composition from model output; we discuss changes in this optical property after long-range transport. Furthermore, we examine how the AERONET-derived aerosol properties respond to dust mineralogy. Finally we use AERONET data to evaluate model-based single scattering albedo. Acknowledgement We would like to thank the AERONET network and the principal investigators, as well as their staff, for establishing and maintaining the AERONET sites used in this work.

  14. Laboratory estimate of the regional shortwave refractive index and single scattering albedo of mineral dust from major sources worldwide

    Science.gov (United States)

    Di Biagio, C.; Formenti, P.; Caponi, L.; Cazaunau, M.; Pangui, E.; Journet, E.; Nowak, S.; Caquineau, S.; Andreae, M. O.; Kandler, K.; Saeed, T.; Piketh, S.; Seibert, D.; Williams, E.; Balkanski, Y.; Doussin, J. F.

    2017-12-01

    Mineral dust is one of the most abundant aerosol species in the atmosphere and strongly contributes to the global and regional direct radiative effect. Still large uncertainties persist on the magnitude and overall sign of the dust direct effect, where indeed one of the main unknowns is how much mineral dust absorbs light in the shortwave (SW) spectral range. Aerosol absorption is represented both by the imaginary part (k) of the complex refractive index or the single scattering albedo (SSA, i.e. the ratio of the scattering to extinction coefficient). In this study we present a new dataset of SW complex refractive indices and SSA for mineral dust aerosols obtained from in situ measurements in the 4.2 m3 CESAM simulation chamber at LISA (Laboratoire Interuniversitaire des Systemes Atmospheriques) in Créteil, France. Investigated dust aerosol samples were issued from major desert sources worldwide, including the African Sahara and Sahel, Eastern Asia, the Middle East, Southern Africa, Australia, and the Americas, with differing iron oxides content. Results from the present study provide a regional mapping of the SW absorption by dust and show that the imaginary part of the refractive index largely varies (by up to a factor 6, 0.003-0.02 at 370 nm and 0.001-0.003 at 950 nm) for the different source areas due to the change in the particle iron oxide content. The SSA for dust varies between 0.75-0.90 at 370 nm and 0.95-0.99 at 950 nm, with the largest absorption observed for Sahelian and Australian dust aerosols. Our range of variability for k and SSA is well bracketed by already published literature estimates, but suggests that regional‒dependent values should be used in models. The possible relationship between k and the dust iron oxides content is investigated with the aim of providing a parameterization of the regional‒dependent dust absorption to include in climate models.

  15. Summer and winter time heterogeneity in aerosol single scattering albedo over the northwestern Atlantic Ocean during the TCAP field campaign: Relationship to chemical composition and mixing state

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    Berg, L. K.; Chand, D.; Fast, J. D.; Zelenyuk, A.; Wilson, J. M.; Sedlacek, A. J., III; Tomlinson, J. M.; Hubbe, J. M.; Comstock, J. M.; Mei, F.; Kassianov, E.; Schmid, B.

    2015-12-01

    Aerosol play crucial role in earth's radiative budget by scattering and absorbing solar radiation. The impact of aerosol on radiation budget depend on several factors including single scattering albedo (SSA), composition, and the growth processes, like coating or mixing. We describe findings relevant to optical properties of aerosol characterized over the Cape Cod and nearby northwest Atlantic Ocean during the Two Column Aerosol Project (TCAP) during the summer (July 2012) and winter (February 2013) campaigns. The average single scattering albedo (SSA) shows distinctly different vertical profiles during the summer and winter periods. During the summer study period, the average SSA is greater than 0.95 near surface, it increases to 0.97 until an altitude of 2.5 km, and then decreases to 0.94 at top of the column near 4 km. In contrast, during the winter study period the average SSA is less than 0.93 and decreases with height reaching an average value of 0.87 near the top of the column. The large difference in summer and winter time SSA is linked to the presence of biomass burning (BB) aerosol rather than black carbon or soot in both seasons. In our study, the BB on average is factor of two higher in free troposphere (FT) during summer and more than a factor of two higher in the boundary layer during winter. Single particle analysis indicates that the average profiles of refractory black carbon (rBC) mass are similar in both seasons. The average rBC size are similar at all altitudes sampled (0-4 km) in summer time but different during winter time. In addition, the particles sampled in the summertime FT appear to be more aged than those seen during winter. The observed large heterogeneity in SSA and its links to the particle coating and composition highlights the importance of aging and mixing processes of aerosol in this region and represents a challenge for both regional and global scale models.

  16. On Spectral Invariance of Single Scattering Albedo for Water Droplets and Ice Crystals at Weakly Absorbing Wavelengths

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    Marshak, Alexander; Knyazikhin, Yuri; Chiu, J. Christine; Wiscombe, Warren J.

    2012-01-01

    The single scattering albedo omega(sub O lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength lambda and droplet size r. This note shows that for water droplets at weakly absorbing wavelengths, the ratio omega(sub O lambda)(r)/omega(sub O lambda)(r (sub O)) of two single scattering albedo spectra is a linear function of omega(sub O lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo spectrum omega(sub O lambda)(r) via one known spectrum omega(sub O lambda)(r (sub O)). We provide a simple physical explanation of the discovered relationship. Similar linear relationships were found for the single scattering albedo spectra of non-spherical ice crystals.

  17. Chemical Characterization and Single Scattering Albedo of Atmospheric Aerosols Measured at Amami-Oshima, Southwest Japan, During Spring Seasons

    Science.gov (United States)

    Tsuruta, H.; Yabuki, M.; Takamura, T.; Sudo, S.; Yonemura, S.; Shirasuna, Y.; Hirano, K.; Sera, K.; Maeda, T.; Hayasaka, T.; Nakajima, T.

    2008-12-01

    An intensive field program was performed to measure atmospheric aerosols at Amami-Oshima, a small island located at southwest Japan, in the spring season of 2001, 2003, and 2005 under the ACE-Asia, APEX and ABC-EAREX2005 projects. Chemical analysis of the fine and coarse aerosols was made for elemental carbon (EC) and organic carbon, water soluble ions, and trace elements. Single scattering albedo (SSA) of aerosols was independently estimated by two methods. The one (SSAc) is by chemical compositions assuming a half internal mixture between EC and non sea-salt sulfate, and the other (SSAo) is by optical measurements of scattering coefficient and absorption coefficient. The backward trajectory analysis showed that the aerosol concentrations in the air masses arrived at Amami, were much higher from the Asian Continent than from other regions, and two types of aerosol enhancement were observed. The one was caused by polluted air masses from the urban-industrial area of east-coast China, the other was by high mineral dusts due to large- scale dust storms in the desert regions of northwest China. The SSAc was in a range of 0.87-0.98, and in good agreement with the SSAo after some corrections for original scattering and absorption coefficients. The SSAc showed no significant difference between the air masses from the polluted area and the desert regions. The negative correlation between the SSAc and EC was divided into two groups depending on the concentration of non sea-salt sulfate, while the increase in mineral dusts did not show any correlation with the SSAc.

  18. A Seasonal Trend of Single Scattering Albedo in Southern African Biomass-burning Particles: Implications for Satellite Products and Estimates of Emissions for the World's Largest Biomass-burning Source

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Mukelabai, M. M.; Piketh, S. J.; Torres, O.; Jethva, H. T.; Hyer, E. J.; Ward, D. E.; Dubovik, O.; hide

    2013-01-01

    As a representative site of the southern African biomass-burning region, sun-sky data from the 15 year Aerosol Robotic Network (AERONET) deployment at Mongu, Zambia, was analyzed. For the biomass-burning season months (July-November), we investigate seasonal trends in aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals. The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from approx.. 0.84 in July to approx. 0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Angstrom exponent (440-870 nm; r(exp 2) = 0.02). A significant downward seasonal trend in imaginary refractive index (r(exp 2) = 0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, burning season SSA retrievals for the Etosha Pan, Namibia AERONET site also show very similar increasing single scattering albedo values and decreasing imaginary refractive index as the season progresses. Furthermore, retrievals of SSA at 388 nm from the Ozone Monitoring Instrument satellite sensor show similar seasonal trends as observed by AERONET and suggest that this seasonal shift is widespread throughout much of southern Africa. A seasonal shift in the satellite retrieval bias of aerosol optical depth from the Moderate Resolution Imaging Spectroradiometer collection 5 dark target algorithm is consistent with this seasonal SSA trend since the algorithm assumes a constant value of SSA. Multi-angle Imaging Spectroradiometer, however, appears less sensitive to the absorption-induced bias.

  19. A seasonal trend of single scattering albedo in southern African biomass-burning particles: Implications for satellite products and estimates of emissions for the world's largest biomass-burning source

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Mukelabai, M. M.; Piketh, S. J.; Torres, O.; Jethva, H. T.; Hyer, E. J.; Ward, D. E.; Dubovik, O.; Sinyuk, A.; Schafer, J. S.; Giles, D. M.; Sorokin, M.; Smirnov, A.; Slutsker, I.

    2013-06-01

    As a representative site of the southern African biomass-burning region, sun-sky data from the 15 year Aerosol Robotic Network (AERONET) deployment at Mongu, Zambia, was analyzed. For the biomass-burning season months (July-November), we investigate seasonal trends in aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals. The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from 0.84 in July to 0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Ångström exponent (440-870 nm; r2 = 0.02). A significant downward seasonal trend in imaginary refractive index (r2 = 0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, burning season SSA retrievals for the Etosha Pan, Namibia AERONET site also show very similar increasing single scattering albedo values and decreasing imaginary refractive index as the season progresses. Furthermore, retrievals of SSA at 388 nm from the Ozone Monitoring Instrument satellite sensor show similar seasonal trends as observed by AERONET and suggest that this seasonal shift is widespread throughout much of southern Africa. A seasonal shift in the satellite retrieval bias of aerosol optical depth from the Moderate Resolution Imaging Spectroradiometer collection 5 dark target algorithm is consistent with this seasonal SSA trend since the algorithm assumes a constant value of SSA. Multi-angle Imaging Spectroradiometer, however, appears less sensitive to the absorption-induced bias.

  20. Determination of the single scattering albedo and direct radiative forcing of biomass burning aerosol with data from the MODIS (Moderate Resolution Imaging Spectroradiometer) satellite instrument

    Science.gov (United States)

    Zhu, Li

    Biomass burning aerosols absorb and scatter solar radiation and therefore affect the energy balance of the Earth-atmosphere system. The single scattering albedo (SSA), the ratio of the scattering coefficient to the extinction coefficient, is an important parameter to describe the optical properties of aerosols and to determine the effect of aerosols on the energy balance of the planet and climate. Aerosol effects on radiation also depend strongly on surface albedo. Large uncertainties remain in current estimates of radiative impacts of biomass burning aerosols, due largely to the lack of reliable measurements of aerosol and surface properties. In this work we investigate how satellite measurements can be used to estimate the direct radiative forcing of biomass burning aerosols. We developed a method using the critical reflectance technique to retrieve SSA from the Moderate Resolution Imaging Spectroradiometer (MODIS) observed reflectance at the top of the atmosphere (TOA). We evaluated MODIS retrieved SSAs with AErosol RObotic NETwork (AERONET) retrievals and found good agreements within the published uncertainty of the AERONET retrievals. We then developed an algorithm, the MODIS Enhanced Vegetation Albedo (MEVA), to improve the representations of spectral variations of vegetation surface albedo based on MODIS observations at the discrete 0.67, 0.86, 0.47, 0.55, 1.24, 1.64, and 2.12 mu-m channels. This algorithm is validated using laboratory measurements of the different vegetation types from the Amazon region, data from the Johns Hopkins University (JHU) spectral library, and data from the U.S. Geological Survey (USGS) digital spectral library. We show that the MEVA method can improve the accuracy of flux and aerosol forcing calculations at the TOA compared to more traditional interpolated approaches. Lastly, we combine the MODIS retrieved biomass burning aerosol SSA and the surface albedo spectrum determined from the MEVA technique to calculate TOA flux and

  1. Application of AERONET Single Scattering Albedo and Absorption Angstrom Exponent to Classify Dominant Aerosol Types during DRAGON Campaigns

    Science.gov (United States)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Schafer, J.; Crawford, J. H.; Kim, J.; Sano, I.; Liew, S.; Salinas Cortijo, S. V.; Chew, B. N.; Lim, H.; Smirnov, A.; Sorokin, M.; Kenny, P.; Slutsker, I.

    2013-12-01

    Aerosols can have major implications on human health by inducing respiratory diseases due to inhalation of fine particles from biomass burning smoke or industrial pollution and on radiative forcing whereby the presence of absorbing aerosol particles (e.g., black carbon) increases atmospheric heating. Aerosol classification techniques have utilized aerosol loading and aerosol properties derived from multi-spectral and multi-angle observations by ground-based (e.g., AERONET) and satellite instrumentation (e.g., MISR). Aerosol Robotic Network (AERONET) data have been utilized to determine aerosol types by implementing various combinations of measured aerosol optical depth or retrieved size and absorption aerosol properties (e.g., Gobbi et al., 2007; Russell et al., 2010). Giles et al. [2012] showed single scattering albedo (SSA) relationship with extinction Angstrom exponent (EAE) can provide an estimate of the general classification of dominant aerosol types (i.e., desert dust, urban/industrial pollution, biomass burning smoke, and mixtures) based on data from ~20 AERONET sites located in known aerosol source regions. In addition, the absorption Angstrom exponent relationship with EAE can provide an indication of the dominant absorbing aerosol type such as dust, black carbon, brown carbon, or mixtures of them. These classification techniques are applied to the AERONET Level 2.0 quality assured data sets collected during Distributed Regional Aerosol Gridded Observational Network (DRAGON) campaigns in Maryland (USA), Japan, South Korea, Singapore, Penang (Malaysia), and California (USA). An analysis of aerosol type classification for DRAGON sites is performed as well as an assessment of the spatial variability of the aerosol types for selected DRAGON campaigns. Giles, D. M., B. N. Holben, T. F. Eck, A. Sinyuk, A. Smirnov, I. Slutsker, R. R. Dickerson, A. M. Thompson, and J. S. Schafer (2012), An analysis of AERONET aerosol absorption properties and classifications

  2. Saharan dust events at the Jungfraujoch: detection by wavelength dependence of the single scattering albedo and first climatology analysis

    Directory of Open Access Journals (Sweden)

    M. Collaud Coen

    2004-01-01

    Full Text Available Scattering and absorption coefficients have been measured continuously at several wavelengths since March 2001 at the high altitude site Jungfraujoch (3580ma.s.l.. From these data, the wavelength dependences of the Ångström exponent and particularly of the single scattering albedo are determined. While the exponent of the single scattering albedo usually increases with wavelength, it decreases with wavelength during Saharan dust events (SDE due to the greater size of the mineral aerosol particles and their different chemical composition. This change in the sign of the single scattering exponent turns out to be a sensitive means for detecting Saharan dust events. The occurrence of SDE detected by this new method was confirmed by visual inspection of filter colors and by studying long-range back-trajectories. An examination of SDE over a 22-month period shows that SDE are more frequent during the March-June period as well as during October and November. The trajectory analysis indicated a mean traveling time of 96.5h, with the most important source countries situated in the northern and north-western part of the Saharan desert. Most of the SDE do not lead to a detectable increase of the 48-h total suspended particulate matter (TSP concentration at the Jungfraujoch. During Saharan dust events, the average contribution of this dust to hourly TSP at the Jungfraujoch is 16µg/m3, which corresponds to an annual mean of 0.8µg/m3 or 24% of TSP.

  3. Vertical variability of aerosol single-scattering albedo and equivalent black carbon concentration based on in-situ and remote sensing techniques during the iAREA campaigns in Ny-Ålesund

    Science.gov (United States)

    Markowicz, K. M.; Ritter, C.; Lisok, J.; Makuch, P.; Stachlewska, I. S.; Cappelletti, D.; Mazzola, M.; Chilinski, M. T.

    2017-09-01

    This work presents a methodology for obtaining vertical profiles of aerosol single scattering properties based on a combination of different measurement techniques. The presented data were obtained under the iAREA (Impact of absorbing aerosols on radiative forcing in the European Arctic) campaigns conducted in Ny-Ålesund (Spitsbergen) during the spring seasons of 2015-2017. The retrieval uses in-situ observations of black carbon concentration and absorption coefficient measured by a micro-aethalometer AE-51 mounted onboard a tethered balloon, as well as remote sensing data obtained from sun photometer and lidar measurements. From a combination of the balloon-borne in-situ and the lidar data, we derived profiles of single scattering albedo (SSA) as well as absorption, extinction, and aerosol number concentration. Results have been obtained in an altitude range from about 400 m up to 1600 m a.s.l. and for cases with increased aerosol load during the Arctic haze seasons of 2015 and 2016. The main results consist of the observation of increasing values of equivalent black carbon (EBC) and absorption coefficient with altitude, and the opposite trend for aerosol concentration for particles larger than 0.3 μm. SSA was retrieved with the use of lidar Raman and Klett algorithms for both 532 and 880 nm wavelengths. In most profiles, SSA shows relatively high temporal and altitude variability. Vertical variability of SSA computed from both methods is consistent; however, some discrepancy is related to Raman retrieval uncertainty and absorption coefficient estimation from AE-51. Typically, very low EBC concentration in Ny-Ålesund leads to large error in the absorbing coefficient. However, SSA uncertainty for both Raman and Klett algorithms seems to be reasonable, e.g. SSA of 0.98 and 0.95 relate to an error of ±0.01 and ± 0.025, respectively.

  4. Using the Aerosol Single Scattering Albedo and Angstrom Exponent from AERONET to Determine Aerosol Origins and Mixing States over the Indo-Gangetic Plain

    Science.gov (United States)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Slutsker, I.; Smirnov, A.; Schafer, J. S.; Dickerson, R. R.; Thompson, A. M.; Tripathi, S. N.; Singh, R. P.; Ghauri, B.

    2012-12-01

    Aerosol mixtures—whether dominated by dust, carbon, sulfates, nitrates, sea salt, or mixtures of them—complicate the retrieval of remotely sensed aerosol properties from satellites and possibly increase the uncertainty of the aerosol radiative impact on climate. Major aerosol source regions in South Asia include the Thar Desert as well as agricultural lands, Himalayan foothills, and large urban centers in and near the Indo-Gangetic Plain (IGP). Over India and Pakistan, seasonal changes in meteorology, including the monsoon (June-September), significantly affect the transport, lifetime, and type of aerosols. Strong monsoonal winds can promote long range transport of dust resulting in mixtures of dust and carbonaceous aerosols, while more stagnant synoptic conditions (e.g., November-January) can prolong the occurrence of urban/industrial pollution, biomass burning smoke, or mixtures of them over the IGP. Aerosol Robotic Network (AERONET) Sun/sky radiometer data are analyzed to show the aerosol optical depth (AOD) seasonality and aerosol dominant mixing states. The Single Scattering Albedo (SSA) and extinction Angstrom exponent (EAE) relationship has been shown to provide sound clustering of dominant aerosol types using long term AERONET site data near known source regions [Giles et al., 2012]. In this study, aerosol type partitioning using the SSA (440 nm) and EAE (440-870 nm) relationship is further developed to quantify the occurrence of Dust, Mixed (e.g., dust and carbonaceous aerosols), Urban/Industrial (U/I) pollution, and Biomass Burning (BB) smoke. Based on EAE thresholds derived from the cluster analysis (for AOD440nm>0.4), preliminary results (2001-2010) for Kanpur, India, show the overall contributions of each dominant particle type (rounded to the nearest 10%): 10% for Dust (EAE≤0.25), 60% for Mixed (0.251.25). In the IGP, BB aerosols may have varying sizes (e.g., corresponding to 1.2India and Pakistan are also analyzed using available AERONET

  5. Measurement of size-dependent single scattering albedo of fresh biomass burning aerosols using the extinction-minus-scattering technique with a combination of cavity ring-down spectroscopy and nephelometry

    Directory of Open Access Journals (Sweden)

    S. Singh

    2016-11-01

    Full Text Available Biomass burning (BB aerosols have a significant effect on regional climate, and represent a significant uncertainty in our understanding of climate change. Using a combination of cavity ring-down spectroscopy and integrating nephelometry, the single scattering albedo (SSA and Ångstrom absorption exponent (AAE were measured for several North American biomass fuels. This was done for several particle diameters for the smoldering and flaming stage of white pine, red oak, and cedar combustion. Measurements were done over a wider wavelength range than any previous direct measurement of BB particles. While the offline sampling system used in this work shows promise, some changes in particle size distribution were observed, and a thorough evaluation of this method is required. The uncertainty of SSA was 6 %, with the truncation angle correction of the nephelometer being the largest contributor to error. While scattering and extinction did show wavelength dependence, SSA did not. SSA values ranged from 0.46 to 0.74, and were not uniformly greater for the smoldering stage than the flaming stage. SSA values changed with particle size, and not systematically so, suggesting the proportion of tar balls to fractal black carbon change with fuel type/state and particle size. SSA differences of 0.15–0.4 or greater can be attributed to fuel type or fuel state for fresh soot. AAE values were quite high (1.59–5.57, despite SSA being lower than is typically observed in wildfires. The SSA and AAE values in this work do not fit well with current schemes that relate these factors to the modified combustion efficiency of a burn. Combustion stage, particle size, fuel type, and fuel condition were found to have the most significant effects on the intrinsic optical properties of fresh soot, though additional factors influence aged soot.

  6. SCAP-82, Single Scattering, Albedo Scattering, Point-Kernel Analysis in Complex Geometry

    International Nuclear Information System (INIS)

    Disney, R.K.; Vogtman, S.E.

    1987-01-01

    1 - Description of problem or function: SCAP solves for radiation transport in complex geometries using the single or albedo scatter point kernel method. The program is designed to calculate the neutron or gamma ray radiation level at detector points located within or outside a complex radiation scatter source geometry or a user specified discrete scattering volume. Geometry is describable by zones bounded by intersecting quadratic surfaces within an arbitrary maximum number of boundary surfaces per zone. Anisotropic point sources are describable as pointwise energy dependent distributions of polar angles on a meridian; isotropic point sources may also be specified. The attenuation function for gamma rays is an exponential function on the primary source leg and the scatter leg with a build- up factor approximation to account for multiple scatter on the scat- ter leg. The neutron attenuation function is an exponential function using neutron removal cross sections on the primary source leg and scatter leg. Line or volumetric sources can be represented as a distribution of isotropic point sources, with un-collided line-of-sight attenuation and buildup calculated between each source point and the detector point. 2 - Method of solution: A point kernel method using an anisotropic or isotropic point source representation is used, line-of-sight material attenuation and inverse square spatial attenuation between the source point and scatter points and the scatter points and detector point is employed. A direct summation of individual point source results is obtained. 3 - Restrictions on the complexity of the problem: - The SCAP program is written in complete flexible dimensioning so that no restrictions are imposed on the number of energy groups or geometric zones. The geometric zone description is restricted to zones defined by boundary surfaces defined by the general quadratic equation or one of its degenerate forms. The only restriction in the program is that the total

  7. Aerosol ultraviolet absorption experiment (2002 to 2004), part 2: absorption optical thickness, refractive index, and single scattering albedo

    Science.gov (United States)

    Krotkov, Nickolay A.; Bhartia, Pawan K.; Herman, Jay R.; Slusser, James R.; Scott, Gwendolyn R.; Labow, Gordon J.; Vasilkov, Alexander P.; Eck, Tom; Doubovik, Oleg; Holben, Brent N.

    2005-04-01

    Compared to the visible spectral region, very little is known about aerosol absorption in the UV. Without such information it is impossible to quantify the causes of the observed discrepancy between modeled and measured UV irradiances and photolysis rates. We report results of a 17-month aerosol column absorption monitoring experiment conducted in Greenbelt, Maryland, where the imaginary part of effective refractive index k was inferred from the measurements of direct and diffuse atmospheric transmittances by a UV-multifilter rotating shadowband radiometer [UV-MFRSR, U.S. Department of Agriculture (USDA) UV-B Monitoring and Research Network]. Colocated ancillary measurements of aerosol effective particle size distribution and refractive index in the visible wavelengths [by CIMEL sun-sky radiometers, National Aeronautics and Space Administration (NASA) Aerosol Robotic Network (AERONET)], column ozone, surface pressure, and albedo constrain the forward radiative transfer model input, so that a unique solution for k is obtained independently in each UV-MFRSR spectral channel. Inferred values of k are systematically larger in the UV than in the visible wavelengths. The inferred k values enable calculation of the single scattering albedo ω, which is compared with AERONET inversions in the visible wavelengths. On cloud-free days with high aerosol loadings [τext(440)>0.4], ω is systematically lower at 368 nm (=0.94) than at 440 nm (=0.96), however, the mean ω differences (0.02) are within expected uncertainties of ω retrievals (~0.03). The inferred ω is even lower at shorter UV wavelengths (~=0.92), which might suggest the presence of selectively UV absorbing aerosols. We also find that decreases with decrease in aerosol loading. This could be due to real changes in the average aerosol composition between summer and winter months at the Goddard Space Flight Center (GSFC) site.

  8. Aerosol single-scattering albedo and asymmetry parameter from MFRSR observations during the ARM Aerosol IOP 2003

    Directory of Open Access Journals (Sweden)

    E. I. Kassianov

    2007-06-01

    Full Text Available Multi-filter Rotating Shadowband Radiometers (MFRSRs provide routine measurements of the aerosol optical depth (τ at six wavelengths (0.415, 0.5, 0.615, 0.673, 0.870 and 0.94 μm. The single-scattering albedo0 is typically estimated from the MFRSR measurements by assuming the asymmetry parameter (g. In most instances, however, it is not easy to set an appropriate value of g due to its strong temporal and spatial variability. Here, we introduce and validate an updated version of our retrieval technique that allows one to estimate simultaneously π0 and g for different types of aerosol. We use the aerosol and radiative properties obtained during the Atmospheric Radiation Measurement (ARM Program's Aerosol Intensive Operational Period (IOP to validate our retrieval in two ways. First, the MFRSR-retrieved optical properties are compared with those obtained from independent surface, Aerosol Robotic Network (AERONET, and aircraft measurements. The MFRSR-retrieved optical properties are in reasonable agreement with these independent measurements. Second, we perform radiative closure experiments using the MFRSR-retrieved optical properties. The calculated broadband values of the direct and diffuse fluxes are comparable (~5 W/m2 to those obtained from measurements.

  9. Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon

    Directory of Open Access Journals (Sweden)

    D. A. Lack

    2010-05-01

    Full Text Available The presence of clear coatings on atmospheric black carbon (BC particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate that the enhancement of light absorption (EAbs by atmospheric black carbon (BC when it is coated in mildly absorbing material (CBrown is reduced relative to the enhancement induced by non-absorbing coatings (CClear. This reduction, sensitive to both the CBrown coating thickness and imaginary refractive index (RI, can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of CClear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with CBrown is shown to be important to the calculated single scatter albedo only when models treat BC as large spherical cores (>50 nm. For smaller BC cores (or fractal agglomerates consideration of the BC and CBrown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It has often been assumed that observation of an absorption Angström exponent (AAE>1 indicates absorption by a non-BC aerosol. Here, it is shown that BC cores coated in CClear can reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to CBrown within ambient particles. However, an AAE<1.6 does not exclude the possibility of CBrown; rather CBrown cannot be confidently assigned unless AAE>1.6. Comparison of these model

  10. Continental pollution in the Western Mediterranean basin: large variability of the aerosol single scattering albedo and influence on the direct shortwave radiative effect

    Directory of Open Access Journals (Sweden)

    C. Di Biagio

    2016-08-01

    Full Text Available Pollution aerosols strongly influence the composition of the Western Mediterranean basin, but at present little is known on their optical properties. We report in this study in situ observations of the single scattering albedo (ω of pollution aerosol plumes measured over the Western Mediterranean basin during the TRAQA (TRansport and Air QuAlity airborne campaign in summer 2012. Cases of pollution export from different source regions around the basin and at different altitudes between  ∼  160 and 3500 m above sea level were sampled during the flights. Data from this study show a large variability of ω, with values between 0.84–0.98 at 370 nm and 0.70–0.99 at 950 nm. The single scattering albedo generally decreases with the wavelength, with some exception associated to the mixing of pollution with sea spray or dust particles over the sea surface. The lowest values of ω (0.84–0.70 between 370 and 950 nm are measured in correspondence of a fresh plume possibly linked to ship emissions over the basin. The range of variability of ω observed in this study seems to be independent of the source region around the basin, as well as of the altitude and aging time of the plumes. The observed variability of ω reflects in a large variability for the complex refractive index of pollution aerosols, which is estimated to span in the large range 1.41–1.77 and 0.002–0.097 for the real and the imaginary parts, respectively, between 370 and 950 nm. Radiative calculations in clear-sky conditions were performed with the GAME radiative transfer model to test the sensitivity of the aerosol shortwave Direct Radiative Effect (DRE to the variability of ω as observed in this study. Results from the calculations suggest up to a 50 and 30 % change of the forcing efficiency (FE, i.e. the DRE per unit of optical depth, at the surface (−160/−235 W m−2 τ−1 at 60° solar zenith angle and at the Top-Of-Atmosphere (−137/−92

  11. Influence of soot mixing state on aerosol light absorption and single scattering albedo during air mass aging at a polluted regional site in northeastern China

    Science.gov (United States)

    Cheng, Y. F.; Berghof, M.; Garland, R. M.; Wiedensohler, A.; Wehner, B.; Müller, T.; Su, H.; Zhang, Y. H.; Achtert, P.; Nowak, A.; PöSchl, U.; Zhu, T.; Hu, M.; Zeng, L. M.

    2009-01-01

    An aerosol optical closure study was performed using the observed high time- and size-resolved soot mixing states determined by a Volatility Tandem Differential Mobility Analyzer (VTDMA) at a polluted regional site, Yufa, in the south of Beijing during the summer of 2006. Good agreement was found between the simulated and measured aerosol absorption (σap, R = 0.9) and scattering (σsp, R ≥ 0.95). The soot mixing state at Yufa can be generally determined by VTDMA, in terms of properly predicting the σap using a simple optical model combined with spherical homogeneous and core-shell coated Mie codes. The possible uncertainties in the modeled σap were discussed. Rapid soot aging was observed, which led to large variations in the fractional contributions to σap by externally mixed and coated soot. On average, about 37% of the σap (˜10-60%) arose by the coated soot. The coating enhancement in σap and σsp of the coated soot can reach up to a factor of 8-10 within several hours owing to the secondary processing during daytime. It was contributed not only by the increased thickness of coating shell, but also the transition of soot from externally mixed to coated one. Hence, assuming constant soot mixing state for the regional climate model is not realistic and may lead to uncertainties. In the highly polluted region in northeastern China, the aerosol single scattering albedo may increase very fast owing to the rapid secondary particle formation and condensation (up to 0.90-0.95). This increase took place although the concurrent coating processing enhanced the light absorption capability of soot.

  12. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 2; Derivation of Aerosol Real Refractive Index, Single-Scattering Albedo, and Humidification Factor using Raman Lidar and Aircraft Size Distribution

    Science.gov (United States)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Poellot, M.; Kaufman, Y. J.

    1998-01-01

    Aerosol backscattering and extinction profiles measured by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site during two nights in April 1994 are discussed. These profiles are shown to be consistent with the simultaneous aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter flown on the University of North Dakota Citation aircraft. We describe a technique which uses both lidar and PCASP measurements to derive the dependence of particle size on relative humidity, the aerosol real refractive index n, and estimate the effective single-scattering albedo Omega(sub 0). Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); Omega(sub 0) varied between 0.7 and 1.0. The single-scattering albedo derived from this technique is sensitive to the manner in which absorbing particles are represented in the aerosol mixture; representing the absorbing particles as an internal mixture rather than the external mixture assumed here results in generally higher values of Omega(sub 0). The lidar measurements indicate that the change in particle size with relative humidity as measured by the PCASP can be represented in the form discussed by Hattel with the exponent gamma = 0.3 + or - 0.05. The variations in aerosol optical and physical characteristics captured in the lidar and aircraft size distribution measurements are discussed in the context of the meteorological conditions observed during the experiment.

  13. Investigation of snow single scattering properties based on first order Legendre phase function

    Science.gov (United States)

    Eppanapelli, Lavan Kumar; Casselgren, Johan; Wåhlin, Johan; Sjödahl, Mikael

    2017-04-01

    Angularly resolved bidirectional reflectance measurements were modelled by approximating a first order Legendre expanded phase function to retrieve single scattering properties of snow. The measurements from 10 different snow types with known density and specific surface area (SSA) were investigated. A near infrared (NIR) spectrometer was used to measure reflected light above the snow surface over the hemisphere in the wavelength region of 900-1650 nm. A solver based on discrete ordinate radiative transfer (DISORT) model was used to retrieve the estimated Legendre coefficients of the phase function and a correlation between the coefficients and physical properties of different snow types is investigated. Results of this study suggest that the first two coefficients of the first order Legendre phase function provide sufficient information about the physical properties of snow where the latter captures the anisotropic behaviour of snow and the former provides a relative estimate of the single scattering albedo of snow. The coefficients of the first order phase function were compared with the experimental data and observed that both the coefficients are in good agreement with the experimental data. These findings suggest that our approach can be applied as a qualitative tool to investigate physical properties of snow and also to classify different snow types.

  14. An algorithm to determine backscattering ratio and single scattering albedo

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

    and backscattering coefficients and the remote sensing reflectance are used to obtain a relationship for the backscattering ratio, which is defined as the ratio of the total backscattering to the total scattering in terms of the remote sensing reflectance of two...

  15. Single scattering properties of hydrosols

    Science.gov (United States)

    Mukherjee, L.; Zhai, P.; Hu, Y.

    2017-12-01

    The single scattering or inherent optical properties (IOPs) of hydrosols play an important role in the complete study of ocean optics, ocean color remote sensing, and ocean biogeochemistry research. Measurements show that hydrosols can be of various sizes and shapes, which suggests that general non-spherical models should be considered for the study of IOPs of hydrosols. In this work, the IOPs of randomly oriented non-spherical hydrosols of both absorbing and non-absorbing types are modeled using the Amsterdam Discrete Dipole Approximation (ADDA). We have defined the degree of optical non-sphericity (DONS) and investigated the dependence of DONS on refractive indices, sizes, and aspect ratios. For particles with non-unit aspect ratios, the magnitude of DONS increases with an increase of refractive index and aspect ratio. In general, the value of DONS increases with increase in particle size. The variation of DONS with respect to refractive indices and aspect ratios of the hydrosols makes it an important parameter in the study of ocean optics. Dependence of backscattering fraction on non-sphericity, size, and aspect ratio of the hydrosols is also demonstrated. The modeling of single scattering properties of hydrosols with different microphysical parameters would help to interpret the ocean radiation field measured by in situ or remote sensing sensors. Understanding the IOPs of hydrosols would lead to better radiative transfer models in ocean waters and new remote sensing technologies of hydrosol compositions.

  16. Single-scattering properties of Platonic solids in geometrical-optics regime

    International Nuclear Information System (INIS)

    Zhang Zhibo; Yang Ping; Kattawar, George W.; Wiscombe, Warren J.

    2007-01-01

    We investigate the single-scattering properties of the Platonic solids with size parameters in the geometrical-optics regime at wavelengths 0.66 and 11 μm using the geometrical-optics method. The comparisons between the results for the Platonic solids and four types of spherical equivalence show that the equal-surface-area spherical equivalence has the smallest errors in terms of the extinction cross section at both wavelengths. At a wavelength of 0.66 μm, all the spherical equivalences substantially overestimate the asymmetry factors of the Platonic solids; and in the case of strong absorption, they underestimate the single-scattering albedo. The comparisons also show that the spherical equivalences cannot be used to describe the spatial distribution of scattered intensity associated with a prismatic polyhedron

  17. A spectral geometric model for Compton single scatter in PET based on the single scatter simulation approximation

    Science.gov (United States)

    Kazantsev, I. G.; Olsen, U. L.; Poulsen, H. F.; Hansen, P. C.

    2018-02-01

    We investigate the idealized mathematical model of single scatter in PET for a detector system possessing excellent energy resolution. The model has the form of integral transforms estimating the distribution of photons undergoing a single Compton scattering with a certain angle. The total single scatter is interpreted as the volume integral over scatter points that constitute a rotation body with a football shape, while single scattering with a certain angle is evaluated as the surface integral over the boundary of the rotation body. The equations for total and sample single scatter calculations are derived using a single scatter simulation approximation. We show that the three-dimensional slice-by-slice filtered backprojection algorithm is applicable for scatter data inversion provided that the attenuation map is assumed to be constant. The results of the numerical experiments are presented.

  18. SSA Disability Claim Data

    Data.gov (United States)

    Social Security Administration — The dataset includes fiscal year data for initial claims for SSA disability benefits that were referred to a state agency for a disability determination. Specific...

  19. A spectral geometric model for Compton single scatter in PET based on the single scatter simulation approximation

    DEFF Research Database (Denmark)

    Kazantsev, I.G.; Olsen, Ulrik Lund; Poulsen, Henning Friis

    2018-01-01

    scatter is interpreted as the volume integral over scatter points that constitute a rotation body with a football shape, while single scattering with a certain angle is evaluated as the surface integral over the boundary of the rotation body. The equations for total and sample single scatter calculations...... are derived using a single scatter simulation approximation. We show that the three-dimensional slice-by-slice filtered backprojection algorithm is applicable for scatter data inversion provided that the attenuation map is assumed to be constant. The results of the numerical experiments are presented....

  20. Highlights from 4STAR Sky-Scanning Retrievals of Aerosol Intensive Optical Properties from Multiple Field Campaigns with Detailed Comparisons of SSA Reported During SEAC4RS

    Science.gov (United States)

    Flynn, C. J.; Dahlgren, R. P.; Dunagan, S. E.; Johnson, R. R.; Kacenelenbogen, M. S.; LeBlanc, S. E.; Livingston, J. M.; Redemann, J.; Schmid, B.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Zhang, Q.; Schmidt, S.; Holben, B. N.; Sinyuk, A.; Hair, J. W.; Anderson, B. E.; Ziemba, L. D.

    2015-12-01

    The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument combines airborne sun tracking capabilities of the Ames Airborne Tracking Sun Photometer (AATS-14) with AERONET-like sky-scanning capability and adds state-of-the-art fiber-coupled grating spectrometry to yield hyperspectral measurements of direct solar irradiance and angularly resolved sky radiance. The combination of sun-tracking and sky-scanning capability enables retrievals of wavelength-dependent aerosol optical depth (AOD), mode-resolved aerosol size distribution (SD), asphericity, and complex refractive index, and thus also the scattering phase function, asymmetry parameter, single-scattering albedo (SSA), and absorption aerosol optical thickness (AAOT). From 2012 to 2014 4STAR participated in four major field campaigns: the U.S. Dept. of Energy's TCAP I & II campaigns, and NASA's SEAC4RS and ARISE campaigns. Establishing a strong performance record, 4STAR operated successfully on all flights conducted during each of these campaigns. Sky radiance spectra from scans in either constant azimuth (principal plane) or constant zenith angle (almucantar) were interspersed with direct beam measurements during level legs. During SEAC4RS and ARISE, 4STAR airborne measurements were augmented with flight-level albedo from the collocated Shortwave Spectral Flux Radiometer (SSFR) providing improved specification of below-aircraft radiative conditions for the retrieval. Calibrated radiances and retrieved products will be presented with particular emphasis on detailed comparisons of ambient SSA retrievals and measurements during SEAC4RS from 4STAR, AERONET, HSRL2, and from in situ measurements.

  1. Parameterizations for Cloud Overlapping and Shortwave Single-Scattering Properties for Use in General Circulation and Cloud Ensemble Models.

    Science.gov (United States)

    Chou, Ming-Dah; Suarez, Max J.; Ho, Chang-Hoi; Yan, Michael M.-H.; Lee, Kyu-Tae

    1998-02-01

    Parameterizations for cloud single-scattering properties and the scaling of optical thickness in a partial cloudiness condition have been developed for use in atmospheric models. Cloud optical properties are parameterized for four broad bands in the solar (or shortwave) spectrum; one in the ultraviolet and visible region and three in the infrared region. The extinction coefficient, single-scattering albedo, and asymmetry factor are parameterized separately for ice and water clouds. Based on high spectral-resolution calculations, the effective single-scattering coalbedo of a broad band is determined such that errors in the fluxes at the top of the atmosphere and at the surface are minimized. This parameterization introduces errors of a few percent in the absorption of shortwave radiation in the atmosphere and at the surface.Scaling of the optical thickness is based on the maximum-random cloud-overlapping approximation. The atmosphere is divided into three height groups separated approximately by the 400- and 700-mb levels. Clouds are assumed maximally overlapped within each height group and randomly overlapped among different groups. The scaling is applied only to the maximally overlapped cloud layers in individual height groups. The scaling as a function of the optical thickness, cloud amount, and the solar zenith angle is derived from detailed calculations and empirically adjusted to minimize errors in the fluxes at the top of the atmosphere and at the surface. Different scaling is used for direct and diffuse radiation. Except for a large solar zenith angle, the error in fluxes introduced by the scaling is only a few percent. In terms of absolute error, it is within a few watts per square meter.

  2. SSA State Agency Workload Data

    Data.gov (United States)

    Social Security Administration — The dataset is revised and expanded from 4 to 71 data fields. It includes monthly data from October 2000 onwards for SSA disability cases that were referred to the...

  3. Sand Dune Albedo Feedback

    Directory of Open Access Journals (Sweden)

    Yosef Ashkenazy

    2018-02-01

    Full Text Available Sand dunes cover substantial parts of desert areas. Fully active dunes are bare, while fixed dunes are stabilized by vegetation and biogenic crust, and the dune activity is affected by the wind. Here we suggest the following atmosphere-sand dune feedback: spatial differences in the dunes’ vegetation and biogenic crust cover lead to differences in albedo as the albedo of bare sand is larger than that of vegetation and biogenic crust. This leads to a higher temperature over the vegetated area, resulting in air flow from the bare dune area to the vegetated dune area, thus increasing the wind activity over the vegetated dune area. In turn, this leads to enhanced stress on the vegetation and enhanced dune activity and thus to a decrease in vegetation. These changes in vegetation cover affect the surface albedo, leading to a change in wind activity. We examined this feedback using an atmospheric general circulation model, Weather Research and Forecasting (WRF, in selected regions of the northwestern Negev Desert and the Sahara/Sahel region, and we show that changes in surface albedo do indeed lead to significantly enhanced wind activity over the lower albedo region. We then incorporated this feedback into a simple vegetated dune model, showing that the multiple states associated with active and fixed dunes can be obtained for a larger range of parameters and that the stables states become more extreme (i.e., the fixed dune state becomes more vegetated and the active dune state becomes less vegetated.

  4. Fire-induced albedo change and surface radiative forcing in sub-Saharan Africa savanna ecosystems: Implications for the energy balance

    Science.gov (United States)

    Dintwe, Kebonye; Okin, Gregory S.; Xue, Yongkang

    2017-06-01

    Surface albedo is a critical parameter that controls surface energy balance. In dryland ecosystems, fires play a significant role in decreasing surface albedo, resulting in positive radiative forcing. Here we investigate the long-term effect of fire on surface albedo. We devised a method to calculate short-, medium-, and long-term effect of fire-induced radiative forcing and their relative effects on energy balance. We used Moderate Resolution Imaging Spectroradiometer (MODIS) data in our analysis, covering different vegetation classes in sub-Saharan Africa (SSA). Our analysis indicated that mean short-term fire-induced albedo change in SSA was -0.022, -0.035, and -0.041 for savannas, shrubland, and grasslands, respectively. At regional scale, mean fire-induced albedo change in savannas was -0.018 and -0.024 for northern sub-Saharan of Africa and the southern hemisphere Africa, respectively. The short-term mean fire-induced radiative forcing in burned areas in sub-Saharan Africa (SSA) was 5.41 W m-2, which contributed continental and global radiative forcings of 0.25 and 0.058 W m-2, respectively. The impact of fire in surface albedo has long-lasting effects that varies with vegetation type. The long-term energetic effects of fire-induced albedo change and associated radiative forcing were, on average, more than 19 times greater across SSA than the short-term effects, suggesting that fires exerted far more radiative forcing than previously thought. Taking into account the actual duration of fire's effect on surface albedo, we conclude that the contribution of SSA fires, globally and throughout the year, is 0.12 W m-2. These findings provide crucial information on possible impact of fire on regional climate variability.

  5. BOREAS TE-01 SSA Soil Lab Data

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides a set of soil properties for the SSA. The soil samples were collected at sets of soil pits. Major soil properties include soil...

  6. BOREAS TE-01 SSA Soil Lab Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides a set of soil properties for the SSA. The soil samples were collected at sets of soil pits. Major soil properties include soil horizon; dry...

  7. The colour potentials of SSA-containing mortar

    OpenAIRE

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie; Bache, Anja Margrethe; Goltermann, Per

    2015-01-01

    This paper reports an experimental study of aesthetical qualities of mortar containing sewage sludgeash (SSA). SSA is the residue produced at water treatment plants where incineration of the sludge is applied in order to decrease volume and to prevent pathogens from spreading. Today SSA is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals...

  8. Dicty_cDB: SSA423 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available SS (Link to library) SSA423 (Link to dictyBase) - - - - SSA423F (Link to Original s...ite) SSA423F 443 - - - - - - Show SSA423 Library SS (Link to library) Clone ID SSA423 (Link to dictyBase) Atlas ID - NBRP ID - dict...yBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/...FIIGFFLCLTVFLTFVNSSEIDHQYSLTSSINGSSSGVSNSTDNTGCGEYTSCGDCREDK GCVWCGSEGICTEGTFYGTKPLNINGACKDFMWMQCKIQGRWAILIA...VSNSTDNTGCGEYTSCGDCREDK GCVWCGSEGICTEGTFYGTKPLNINGACKDFMWMQCKIQGRWAILIAAGGAFLIIVFFFI CLCCCCCRRKKDKHYHNIQDDET

  9. Dicty_cDB: SSA581 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available SS (Link to library) SSA581 (Link to dictyBase) - - - Contig-U12576-1 SSA581Z (Link... to Original site) - - SSA581Z 504 - - - - Show SSA581 Library SS (Link to library) Clone ID SSA581 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U12576-1 Original site URL http://dict...SARPLGVAMILIGIDDELGPQLFKVDPAGVFTGYKATAAGEK EQESTNFLEKKFKSNPQLSKDETIQMAISTLQSVLGADLKSSDLEIGICTMDNRKFVIMT DEDI...QHASARPLGVAMILIGIDDELGPQLFKVDPAGVFTGYKATAAGEK EQESTNFLEKKFKSNPQLSKDETIQMAISTLQSVLGADLKSSDLEIGICTMDNRKFVIMT D

  10. Absorption line profiles in a moving atmosphere - A single scattering linear perturbation theory

    Science.gov (United States)

    Hays, P. B.; Abreu, V. J.

    1989-01-01

    An integral equation is derived which linearly relates Doppler perturbations in the spectrum of atmospheric absorption features to the wind system which creates them. The perturbation theory is developed using a single scattering model, which is validated against a multiple scattering calculation. The nature and basic properties of the kernels in the integral equation are examined. It is concluded that the kernels are well behaved and that wind velocity profiles can be recovered using standard inversion techniques.

  11. ISLSCP II MODIS (Collection 4) Albedo, 2002

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The MODIS BRDF/Albedo Product (MOD43B) provides measures of clear sky surface albedo every 16 days. Both white-sky albedo (bihemispherical reflectance) and...

  12. Reuse of sewage sludge ashes (SSA) in cement mixtures: the effect of SSA on the workability of cement mortars.

    Science.gov (United States)

    Monzó, J; Payá, J; Borrachero, M V; Girbés, I

    2003-01-01

    The influence of sewage sludge ash (SSA) on workability of cement mortars has been studied. The irregular morphology of SSA particles produced a decrease of mortar workability. A nonlinear reduction of workability in mortars containing SSA was observed, but when SSA content in mortars was increased the workability reduction was less significant. A superplasticizer is used in order to compensate the decrease of workability produced by SSA. When SSA sized fractions were used, only significant differences in workability for mortars prepared with high water volumes or with the presence of superplasticizer were observed.

  13. Microwave single-scattering properties of randomly oriented soft-ice hydrometeors

    Directory of Open Access Journals (Sweden)

    D. Casella

    2008-11-01

    Full Text Available Large ice hydrometeors are usually present in intense convective clouds and may significantly affect the upwelling radiances that are measured by satellite-borne microwave radiometers – especially, at millimeter-wavelength frequencies. Thus, interpretation of these measurements (e.g., for precipitation retrieval requires knowledge of the single scattering properties of ice particles. On the other hand, shape and internal structure of these particles (especially, the larger ones is very complex and variable, and therefore it is necessary to resort to simplifying assumptions in order to compute their single-scattering parameters.

    In this study, we use the discrete dipole approximation (DDA to compute the absorption and scattering efficiencies and the asymmetry factor of two kinds of quasi-spherical and non-homogeneous soft-ice particles in the frequency range 50–183 GHz. Particles of the first kind are modeled as quasi-spherical ice particles having randomly distributed spherical air inclusions. Particles of the second kind are modeled as random aggregates of ice spheres having random radii. In both cases, particle densities and dimensions are coherent with the snow hydrometeor category that is utilized by the University of Wisconsin – Non-hydrostatic Modeling System (UW-NMS cloud-mesoscale model. Then, we compare our single-scattering results for randomly-oriented soft-ice hydrometeors with corresponding ones that make use of: a effective-medium equivalent spheres, b solid-ice equivalent spheres, and c randomly-oriented aggregates of ice cylinders. Finally, we extend to our particles the scattering formulas that have been developed by other authors for randomly-oriented aggregates of ice cylinders.

  14. Equivalence of internal and external mixture schemes of single scattering properties in vector radiative transfer.

    Science.gov (United States)

    Mukherjee, Lipi; Zhai, Peng-Wang; Hu, Yongxiang; Winker, David M

    2017-05-10

    Polarized radiation fields in a turbid medium are influenced by single-scattering properties of scatterers. It is common that media contain two or more types of scatterers, which makes it essential to properly mix single-scattering properties of different types of scatterers in the vector radiative transfer theory. The vector radiative transfer solvers can be divided into two basic categories: the stochastic and deterministic methods. The stochastic method is basically the Monte Carlo method, which can handle scatterers with different scattering properties explicitly. This mixture scheme is called the external mixture scheme in this paper. The deterministic methods, however, can only deal with a single set of scattering properties in the smallest discretized spatial volume. The single-scattering properties of different types of scatterers have to be averaged before they are input to deterministic solvers. This second scheme is called the internal mixture scheme. The equivalence of these two different mixture schemes of scattering properties has not been demonstrated so far. In this paper, polarized radiation fields for several scattering media are solved using the Monte Carlo and successive order of scattering (SOS) methods and scattering media contain two types of scatterers: Rayleigh scatterers (molecules) and Mie scatterers (aerosols). The Monte Carlo and SOS methods employ external and internal mixture schemes of scatterers, respectively. It is found that the percentage differences between radiances solved by these two methods with different mixture schemes are of the order of 0.1%. The differences of Q/I, U/I, and V/I are of the order of 10 -5 ∼10 -4 , where I, Q, U, and V are the Stokes parameters. Therefore, the equivalence between these two mixture schemes is confirmed to the accuracy level of the radiative transfer numerical benchmarks. This result provides important guidelines for many radiative transfer applications that involve the mixture of

  15. Modeling Snow Aggregates and their Single Scattering Properties: Implications to Snowfall Remote Sensing

    Science.gov (United States)

    Nowell, H.; Liu, G.

    2012-12-01

    With the advent of satellites, we can now observe areas of the globe that have sparse to no ground data coverage. Both active and passive satellite sensors aboard satellites including CloudSat's Cloud Profiling Radar (CPR), Aqua's Advanced Microwave Scanning Radiometer (AMSR-E) and the upcoming Global Precipitation Measurement's (GPM) Dual-Frequency Precipitation Radar (DPR) and GPM Microwave Imager (GMI) study ice and snow particles. A good retrieval algorithm for these satellite sensors can only be developed when the single scattering properties of the snowflakes are accurately calculated in radiative transfer models. This becomes crucial at frequencies at and above the W-band when aggregate ice crystals become detectable by satellite radiometers. Snowflakes are often modeled as spheres or oblate spheroids to ease the complexity of calculations, despite the fact that they are typically aggregates of crystals. For improved accuracy in satellite remote sensing, it is important to model snowflakes as close to nature as possible. Several recent studies model flakes as pristine crystal types [Liu, 2008], generate aggregate flakes as fractals [Ishimoto, 2008] or via the Monte Carlo method [Maruyama and Fujioshi, 2005]. Modeling snowflakes as pristine crystals, however, has the drawback of not accurately reflecting snowflakes as most tend to be aggregates of different crystal types. Other studies where aggregates are generated tend to overlook size-density relationships of aggregate flakes or other studied statistical parameters such as aspect ratio. In an effort to improve available single-scattering properties of aggregate flakes, we developed a new method of generating flakes. Starting out with a six-bullet rosette crystal of accurate size and density, aggregate flakes are generated with two different bullet rosette crystal sizes of 200 and/or 400 microns in maximum dimension. The flakes similarly follow size-density relationships of aggregate as determined from

  16. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003 (OMAERUV) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Aura Ozone Monitoring Instrument level-2 near UV Aerosol data product 'OMAERUV', recently re-processed using an enhanced algorithm, is now released (April 2012)...

  17. OMI/Aura Multi-wavelength Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003 (OMAERO) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Level-2 Aura Ozone Monitoring Instrument (OMI) Aerosol Product (OMAERO) is now available from NASA Goddard Earth Sciences Data and Information Services Center...

  18. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo Daily L3 Global 1x1 deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI-Aura level-3 daily global gridded (1x1 deg) near-UV Aerosol data product OMAERUVd based on the enhanced algorithm is available from the NASA Goddard Earth...

  19. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI/Aura level-2 near UV Aerosol data product 'OMAERUV', recently re-processed using an enhanced algorithm, is now released (April 2012) to the public. The data...

  20. OMI/Aura Multi-wavelength Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The improved Level-2 OMI Aerosol Product 'OMAERO' is now available (http://disc.gsfc.nasa.gov/Aura/OMI/omaero_v003.shtml ) from NASA GSFC Earth Sciences (GES) Data...

  1. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003 NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI/Aura level-2 near UV Aerosol data product 'OMAERUV', recently re-processed using an enhanced algorithm, is now released (April 2012) to the public. The data...

  2. Strong spectral variation of biomass smoke light absorption and single scattering albedo observed with a novel dual-wavelength photoacoustic instrument

    Science.gov (United States)

    Kristin Lewis; William P. Arnott; Hans Moosmuller; Cyle E. Wold

    2008-01-01

    A dual-wavelength photoacoustic instrument operating at 405 and 870 nm was used during the 2006 Fire Lab at Missoula Experiment to measure light scattering and absorption by smoke from the combustion of a variety of biomass fuels. Simultaneous measurements of aerosol light scattering by reciprocal nephelometry within the instrument's acoustic resonator accompany...

  3. Vertical profile of the specific surface area and density of the snow at Dome C and on a transect to Dumont D'Urville, Antarctica – albedo calculations and comparison to remote sensing products

    Directory of Open Access Journals (Sweden)

    J.-C. Gallet

    2011-08-01

    Full Text Available The specific surface area (SSA of snow determines in part the albedo of snow surfaces and the capacity of the snow to adsorb chemical species and catalyze reactions. Despite these crucial roles, almost no value of snow SSA are available for the largest permanent snow expanse on Earth, the Antarctic. We report the first extensive study of vertical profiles of snow SSA near Dome C (DC: 75°06' S, 123°20' E, 3233 m a.s.l. on the Antarctic plateau, and at seven sites during the logistical traverse between Dome C and the French coastal base Dumont D'Urville (DDU: 66°40' S, 140°01' E during the Austral summer 2008–2009. We used the DUFISSS system, which measures the IR reflectance of snow at 1310 nm with an integrating sphere. At DC, the mean SSA of the snow in the top 1 cm is 38 m2 kg−1, decreasing monotonically to 14 m2 kg−1 at a depth of 50 cm. Along the traverse, the snow SSA profile is similar to that at DC in the first 600 km from DC. Closer to DDU, the SSA of the top 5 cm is 23 m2 kg−1, decreasing to 19 m2 kg−1 at 50 cm depth. This difference is attributed to wind, which causes a rapid decrease of surface snow SSA, but forms hard windpacks whose SSA decrease more slowly with time. Since light-absorbing impurities are not concentrated enough to affect albedo, the vertical profiles of SSA and density were used to calculate the spectral albedo of the snow for several realistic illumination conditions, using the DISORT radiative transfer model. A preliminary comparison with MODIS data is presented and our calculations and MODIS data show similar trends.

  4. BOREAS TE-1 SSA Soil Lab Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Knapp, David E. (Editor); Nerbas, Tim; Anderson, Darwin

    2000-01-01

    This data set was collected by TE-1 to provide a set of soil properties for BOREAS investigators in the SSA. The soil samples were collected at sets of soil pits in 1993 and 1994. Each set of soil pits was in the vicinity of one of the five flux towers in the BOREAS SSA. The collected soil samples were sent to a lab, where the major soil properties were determined. These properties include, but are not limited to, soil horizon; dry soil color; pH; bulk density; total, organic, and inorganic carbon; electric conductivity; cation exchange capacity; exchangeable sodium, potassium, calcium, magnesium, and hydrogen; water content at 0.01, 0.033, and 1.5 MPascals; nitrogen; phosphorus; particle size distribution; texture; pH of the mineral soil and of the organic soil; extractable acid; and sulfur. The data are stored in tabular ASCII text files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. ISLSCP II AVHRR Albedo and BRDF, 1995

    Data.gov (United States)

    National Aeronautics and Space Administration — This Albedo and BRDF (Bidirectional Reflectance Distribution Function) data set contains three files containing BRDF parameters, white- sky albedo and black-sky...

  6. Modeling the radiation transfer of discontinuous canopies: results for gap probability and single-scattering contribution

    Science.gov (United States)

    Zhao, Feng; Zou, Kai; Shang, Hong; Ji, Zheng; Zhao, Huijie; Huang, Wenjiang; Li, Cunjun

    2010-10-01

    In this paper we present an analytical model for the computation of radiation transfer of discontinuous vegetation canopies. Some initial results of gap probability and bidirectional gap probability of discontinuous vegetation canopies, which are important parameters determining the radiative environment of the canopies, are given and compared with a 3- D computer simulation model. In the model, negative exponential attenuation of light within individual plant canopies is assumed. Then the computation of gap probability is resolved by determining the entry points and exiting points of the ray with the individual plants via their equations in space. For the bidirectional gap probability, which determines the single-scattering contribution of the canopy, a gap statistical analysis based model was adopted to correct the dependence of gap probabilities for both solar and viewing directions. The model incorporates the structural characteristics, such as plant sizes, leaf size, row spacing, foliage density, planting density, leaf inclination distribution. Available experimental data are inadequate for a complete validation of the model. So it was evaluated with a three dimensional computer simulation model for 3D vegetative scenes, which shows good agreement between these two models' results. This model should be useful to the quantification of light interception and the modeling of bidirectional reflectance distributions of discontinuous canopies.

  7. Single Scattering Detection in Turbin Media Using Single-Phase Structured Illumination Filtering

    Science.gov (United States)

    Berrocal, E.; Johnsson, J.; Kristensson, E.; Alden, M.

    2012-05-01

    This work shows a unique possibility of visualizing the exponential intensity decay due to light extinction, when laser adiation propagates through a homogeneous scattering edium. This observation implies that the extracted intensity mostly riginates from single scattering events. The filtering of this single light scattering intensity is performed by means of a single-phase structured illumination filtering approach. Results from numerical Monte Carlo simulation confirm the experimental findings for an extinction coefficient of μ_e = 0.36 mm^-1. This article demonstrates an original and reliable way of measuring the extinction coefficient of particulate turbid media based on sidescattering imaging. Such an approach has capabilities to replace the commonly used transmission measurement within the intermediate single-to multiple scattering regime where the optical depth ranges between 1 procedure and set-up. Applications of the technique has potential in probing challenging homogeneous scattering media, such as biomedical tissues, turbid emulsions, etc, in situations where dilution cannot be applied and where conventional transmission measurements fail.

  8. Measuring Longitudinal Albedo Variations of Asteroids with Ground-Based, Part-Per-Million Polarimetry

    Science.gov (United States)

    Wiktorowicz, Sloane; Masiero, Joseph R.

    2017-10-01

    The polarization state of asteroids encodes a wealth of information about their surfaces. Linear polarization and albedo of rocky Solar System bodies has long been known to be anticorrelated (the Umov effect): dark surfaces, dominated by single scattering, are strongly polarized, but multiple scattering in bright surfaces randomizes the electric field orientation and reduces polarization. As an asteroid rotates, both shape changes and surface albedo variations affect reflected light flux, causing difficulty in the identification of albedo variations. As a differential technique, however, polarimetry is insensitive to shape changes: as total flux varies with instantaneous cross-sectional area, fractional polarization does not. Thus, rotational variability in linear polarization is a hallmark of albedo inhomogeneity, and it cannot be identified with photometry alone.Until now, polarimeters have only discovered high significance rotational variation of linear polarization for one asteroid, (4) Vesta. We report on Lick 3-m observations of Main Belt asteroids with the POLISH2 polarimeter, which utilizes photoelastic modulators instead of a waveplate. We have not only confirmed rotational variations in (4) Vesta with 12 sigma significance in a single, 4-hour observation, but we have also discovered variations in (1) Ceres (5 sigma detection) and (7) Iris (7 sigma detection). We observe that both (4) Vesta and (7) Iris harbor strong linear polarization variations, due to the presence of significant albedo heterogeneity on their surfaces, while those of (1) Ceres are markedly weaker due to its relatively homogenous surface.Circular polarization, which may originate from multiple scattering or from the phase retardance introduced by a metalliferous surface, has been observed in nearly all Solar System bodies except for asteroids. POLISH2 simultaneously measures linear and circular polarization, and we report the discovery of non-zero circular polarization from (7) Iris with

  9. Albedo matters: Understanding runaway albedo variations on Pluto

    Science.gov (United States)

    Earle, Alissa M.; Binzel, Richard P.; Young, Leslie A.; Stern, S. A.; Ennico, K.; Grundy, W.; Olkin, C. B.; Weaver, H. A.; New Horizons Surface Composition Theme

    2018-03-01

    The data returned from NASA's New Horizons reconnaissance of the Pluto system show striking albedo variations from polar to equatorial latitudes as well as sharp longitudinal boundaries. Pluto has a high obliquity (currently 119°) that varies by 23° over a period of less than 3 million years. This variation, combined with its regressing longitude of perihelion (360° over 3.7 million years), creates epochs of "Super Seasons" where one pole is pointed at the Sun at perihelion, thereby experiencing a short, relatively warm summer followed by its longest possible period of winter darkness. In contrast, the other pole experiences a much longer, less intense summer and a short winter season. We use a simple volatile sublimation and deposition model to explore the relationship between albedo variations, latitude, and volatile sublimation and deposition for the current epoch as well as historical epochs during which Pluto experienced these "Super Seasons." Our investigation quantitatively shows that Pluto's geometry creates the potential for runaway albedo and volatile variations, particularly in the equatorial region, which can sustain stark longitudinal contrasts like the ones we see between Tombaugh Regio and the informally named Cthulhu Regio.

  10. The colour potentials of SSA-containing mortar

    DEFF Research Database (Denmark)

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2015-01-01

    is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals and added to mortar mixes by replacing 20% of the cement. An additional focus was to examine...

  11. The Aesthetical quality of SSA-containing mortar and concrete

    DEFF Research Database (Denmark)

    Kappel, Annemette; Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.

    2014-01-01

    SSA (sewage sludge ash) is resulting ash from the combustion of sewage sludge, and is a method employed at some water treatment plants in order to decrease volume and hygenize the sludge. Today, SSA is with a few exceptions landfilled. As cement production is responsible for app. 5 % of the total...

  12. Radiation pressure in galactic disks: stability, turbulence, and winds in the single-scattering limit

    Science.gov (United States)

    Wibking, Benjamin D.; Thompson, Todd A.; Krumholz, Mark R.

    2018-04-01

    The radiation force on dust grains may be dynamically important in driving turbulence and outflows in rapidly star-forming galaxies. Recent studies focus on the highly optically-thick limit relevant to the densest ultra-luminous galaxies and super star clusters, where reprocessed infrared photons provide the dominant source of electromagnetic momentum. However, even among starburst galaxies, the great majority instead lie in the so-called "single-scattering" limit, where the system is optically-thick to the incident starlight, but optically-thin to the re-radiated infrared. In this paper we present a stability analysis and multidimensional radiation-hydrodynamic simulations exploring the stability and dynamics of isothermal dusty gas columns in this regime. We describe our algorithm for full angle-dependent radiation transport based on the discontinuous Galerkin finite element method. For a range of near-Eddington fluxes, we show that the medium is unstable, producing convective-like motions in a turbulent atmosphere with a scale height significantly inflated compared to the gas pressure scale height and mass-weighted turbulent energy densities of ˜0.01 - 0.1 of the midplane radiation energy density, corresponding to mass-weighted velocity dispersions of Mach number ˜0.5 - 2. Extrapolation of our results to optical depths of 103 implies maximum turbulent Mach numbers of ˜20. Comparing our results to galaxy-averaged observations, and subject to the approximations of our calculations, we find that radiation pressure does not contribute significantly to the effective supersonic pressure support in star-forming disks, which in general are substantially sub-Eddington. We further examine the time-averaged vertical density profiles in dynamical equilibrium and comment on implications for radiation-pressure-driven galactic winds.

  13. ESA-SSA Review of Space Weather Measurement Requirements

    Science.gov (United States)

    Luntama, Juha-Pekka; Glover, Alexi; Hilgers, Alain

    2012-07-01

    The ESA Space Situational Awareness (SSA) Preparatory Programme was started in 2009. The objective of the programme is to support the European independent utilisation of and access to space. The first phase of the ESA SSA system development will be finished in 2012 and the next phase is foreseen to be started after the ESA Ministerial Council meeting in November 2012. The definition of measurement requirements for the Space Weather Segment (SWE) of the ESA SSA system has been based on the space weather service requirements defined the by expected users of the system. This document, SSA SWE Customer Requirements Document (CRD), has been defined in a iterative process together with the members of the SSA User Representative Group (URG) and the delegates representing the European states participating the programme. Based on the SWE CRD, ESA with the support of the European industry has produced two documents: SSA SWE System Requirements Document (SRD) and SSA SWE Product Specification (PS). SWE PS contains the requirements for the measurements data required by the SSA SWE system. The SWE PS document has been recently rigorously reviewed by the SSA URG in the framework of the SSA System Requirements Review (SRR). The support provided by the Steering Board of the ESA Space Weather Working Team (SWWT) in this review was extremely useful. The members of the SWWT SB representing the scientific community and the provisional service providers were able to give very detailed comments regarding the measurement requirements for accuracy, cadence, timeliness, etc. As these parameters will be provisional design and cost drivers for the ESA SSA system, definition of the appropriate values at this point in the programme is crucial. This paper provides an overview of the measurement requirements for the SWE Segment of the ESA SSA Programme. The paper discusses the requirement definition process, the customer and service provider inputs, and the critical requirements as they have

  14. Remote Control Southern Hemisphere SSA Observatory

    Science.gov (United States)

    Ritchie, I.; Pearson, M.; Sang, J.

    2013-09-01

    EOS Space Systems (EOSSS) is a research and development company which has developed custom observatories, camera and telescope systems for space surveillance since 1996, as well as creating several evolutions of systems control software for control of observatories and laser tracking systems. Our primary reserach observatory is the Space Reserach Centre (SRC) at Mount Stromlo Asutralia. The current SRC control systems are designed such that remote control can be offered for real time data collection, noise filtering and flexible session management. Several imaging fields of view are available simultaneously for tracking orbiting objects, with real time imaging to Mag 18. Orbiting objects can have the centroids post processed into orbital determination/ orbital projection (OD/OP) elements. With or without laser tracking of orbiting objects, they can be tracked in terminator conditions and their OD/OP data created, then enhanced by proprietary methods involving ballistic coefficient estimation and OD convergence pinning, using a priori radar elements. Sensors in development include a thermal imager for satellite thermal signature detection. Extending laser tracking range by use of adaptive optics beam control is also in development now. This Southern Hemisphere observatory is in a unique position to facilitate the study of space debris, either stand-alone or as part of a network such as Falcon. Current national and international contracts will enhance the remote control capabilities further, creating a resource ready to go for a wide variety of SSA missions.

  15. Albedos

    Science.gov (United States)

    1993-07-01

    Maize 18 Spring wheat 10 - 25 Wheat 18 Swamp rice 11 Tobacco 19 Paddy rice 12 Cassava 19 Kola nuts 13 Potatos 19 Stubble fields 15 - 17 Yams 19 Sugar...441. Perevertun, M. P., 1957, "Spectral Reflectance of Certain Plants in the Range 650-1200 jm," Trans Asrobotan Sect Acad Sci Kazahk SSR, 5. Posey...Barnes) ATTN: AMSMI-RD-DE-SE Fort McClellan, AL 36205-5020 Gordon Lill, Jr. Redstone Arsenal, AL 35898-5245 NASA/Marshall Space Flight Center Deputy

  16. The colour potentials of SSA-containing mortar

    DEFF Research Database (Denmark)

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2015-01-01

    is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals and added to mortar mixes by replacing 20% of the cement. An additional focus was to examine...... the possibilities to accentuate the colours of the hardened mortar by using paper cuttings in the production of the samples. The result of the experiments showed that a colour scale can be developed from ground SSA, and that paper may have the potential of providing divers textural qualities when it is used...

  17. Neutron albedo effects of underground nuclear explosion

    International Nuclear Information System (INIS)

    Yang Bo; Ying Yangjun; Li Jinhong; Bai Yun

    2013-01-01

    The neutron field distribution is affected by the surrounding medium in the underground nuclear explosion. It will influence the radiation chemical diagnosis. By Monte Carlo simulation, the fuel burnup induced by device and neutron albedo was calculated. The analysis method of albedo effect on radiation chemical diagnosis result under special environment was proposed. Neutron albedo should be considered when capture reaction burnup fraction is used, and then correct analysis can be carried out on the nuclear device.The neutron field distribution is affected by the surrounding medium in the underground nuclear explosion. It will influence the radiation chemical diagnosis. By Monte Carlo simulation, the fuel burnup induced by device and neutron albedo was calculated. The analysis method of albedo effect on radiation chemical diagnosis result under special environment was proposed. Neutron albedo should be considered when capture reaction burnup fraction is used, and then correct analysis can be carried out on the nuclear device. (authors)

  18. The Ultraviolet Albedo of Ganymede

    Science.gov (United States)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  19. CARP: a computer code and albedo data library for use by BREESE, the MORSE albedo package

    International Nuclear Information System (INIS)

    Emmett, M.B.; Rhoades, W.A.

    1978-10-01

    The CARP computer code was written to allow processing of DOT angular flux tapes to produce albedo data for use in the MORSE computer code. An albedo data library was produced containing several materials. 3 tables

  20. BOREAS TF-01 SSA-OA Soil Characteristics Data

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Data collected in support of the effort to characterize and interpret soil information at the SSA-OA tower site in 1994. Data collected include soil...

  1. BOREAS TF-01 SSA-OA Soil Characteristics Data

    Data.gov (United States)

    National Aeronautics and Space Administration — Data collected in support of the effort to characterize and interpret soil information at the SSA-OA tower site in 1994. Data collected include soil respiration,...

  2. TiSSA eelkonverents doktorantidele Tallinnas / Koidu Saame

    Index Scriptorium Estoniae

    Saame, Koidu

    2010-01-01

    Tallinna Ülikoolis toimunud TiSSA doktorantide eelkonverentsist 22.-24. aug. 2010.a. Doktorantide ettekannetest. Esinesid: Hans-Uwe Otto, Andriy Yuryev, Tiina Naarits, Ivar Tröner, Koidu Saame, Maija Jäppinen, Janissa Miettinen

  3. BOREAS TE-18 Biomass Density Image of the SSA

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This biomass density image covers almost the entire BOREAS SSA. The pixels for which biomass density is computed include areas that are in conifer land...

  4. BOREAS TE-18 Biomass Density Image of the SSA

    Data.gov (United States)

    National Aeronautics and Space Administration — This biomass density image covers almost the entire BOREAS SSA. The pixels for which biomass density is computed include areas that are in conifer land cover classes...

  5. Data over the SSA in Raster Format and AEAC Projection

    Data.gov (United States)

    National Aeronautics and Space Administration — GIS layers that describe the soils of the BOREAS SSA. Original data were submitted as vector layers that were then gridded by BOREAS staff to a 30-meter pixel size...

  6. Data over the SSA in Raster Format and AEAC Projection

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: GIS layers that describe the soils of the BOREAS SSA. Original data were submitted as vector layers that were then gridded by BOREAS staff to a 30-meter...

  7. The Critical Role of Experimentation to Further SSA Understanding

    Science.gov (United States)

    Donnelly, P.; Ash, A.

    2016-09-01

    Dstl has developed an approach to explore the challenges of understanding the fundamental principles of SSA through the design and execution of a series of national and international SSA experiments conducted since 2008. These have involved a number of nations within different multi-lateral constructs (such as Combined Space Operations [CSPO] and NATO), and have also served as test case scenarios in support of international SSA research collaboration. It has been found that this experimentally-driven approach has been successful in linking government R&D activities to actual operations with UK MOD; enabling enhanced cooperation with academia through the provision of access to sensors and data; as well as an understanding of the operational imperatives and constraints, not usually available or apparent to these institutions. The experiences of the Dstl team over the past 8 years have yielded a number of lessons learnt that we believe the wider international community would benefit from in relation to effective SSA operations, including how to generate closer relationships between communities across government, industry, academia and operators. This paper describes the overall Dstl approach to a series of SSA experiments designed to inform the UK MOD on the challenges and potential technical solutions related to SSA mission areas. It includes details of the participants, design and execution; and illustrates some major findings of each event to date. Lessons learnt pertinent to the AMOS and wider SSA community are presented that will inform the audience on how this approach may be adopted to meet other SSA scenarios. Finally, it presents the UK roadmap for future experiments identified as possible activities under the CSPO initiative and the EU Space Surveillance and Tracking programme.

  8. Albedo recovery for hyperspectral image classification

    Science.gov (United States)

    Zhan, Kun; Wang, Haibo; Xie, Yuange; Zhang, Chutong; Min, Yufang

    2017-07-01

    Image intensity value is determined by both the albedo component and the shading component. The albedo component describes the physical nature of different objects at the surface of the earth, and land-cover classes are different from each other because of their intrinsic physical materials. We, therefore, recover the intrinsic albedo feature of the hyperspectral image to exploit the spatial semantic information. Then, we use the support vector machine (SVM) to classify the recovered intrinsic albedo hyperspectral image. The SVM tries to maximize the minimum margin to achieve good generalization performance. Experimental results show that the SVM with the intrinsic albedo feature method achieves a better classification performance than the state-of-the-art methods in terms of visual quality and three quantitative metrics.

  9. Role of non-convexity in characterizing single-scattering properties for ensembles of non-spherical precipitation particles

    Science.gov (United States)

    Kuo, K.; Clune, T.; Pearson, C.; Olson, W. S.; Skofronick-Jackson, G.; Gravner, J.; Griffeath, D.

    2010-12-01

    This study improves upon an earlier, preliminary study using only three size bins based on maximum diameter in which it is found that the single-scattering properties of ensembles of non-spherical precipitation particles can be better characterized by considering the non-convexity of these particles. The difficulty of retrievals involving non-spherical particles stems not only from the fact that these particles are not spherical but also the fact that the shape composition of an ensemble of particles is usually unknown and the possibility of its mixture is infinite. Being able to adequately characterize the single-scattering properties of ensembles involving these non-spherical particles with as few parameters as possible is at the heart of solving this thorny remote sensing problem. Inspired by how well three parameters, i.e. water content, effective radius, and effective variance (or their equivalent), characterize the single-scattering properties of an ensemble of spherical particles of varying sizes, we set out to find additional parameters that generalize these three for ensembles of non-spherical particles. We find that a non-convexity measure appears to be one of these additional parameters. Non-convexity is expressed as a ratio of two effective radii derived from the moments of a given particle size distribution (PSD), each of which is in essence a ratio of ensemble particle volume to area. The effective radius in the numerator (denoted as rA) of the non-convexity ratio is based on the projection area of the particle ensemble whereas the one in the denominator (denoted as rS) is based on the surface area. In the preliminary study with PSDs having only three size bins, it is found that variations in the single-scattering properties, such as the scattering and extinction coefficients, the asymmetry factor, and even the scattering phase function, of a particle ensemble with a specified water content are very limited (practically non-existent), if 1) the habit

  10. The colour potentials of SSA-containing mortar:the long version

    OpenAIRE

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie; Bache, Anja Margrethe; Goltermann, Per

    2015-01-01

    This paper reports an experimental study of aesthetical qualities of mortar containing sewage sludgeash (SSA). SSA is the residue produced at water treatment plants where incineration of the sludge is applied in order to decrease volume and to prevent pathogens from spreading. Today SSA is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals...

  11. Clinical and Pathological Roles of Ro/SSA Autoantibody System

    Directory of Open Access Journals (Sweden)

    Ryusuke Yoshimi

    2012-01-01

    Full Text Available Anti-Ro/SSA antibodies are among the most frequently detected autoantibodies against extractable nuclear antigens and have been associated with systemic lupus erythematosus (SLE and Sjögren's syndrome (SS. Although the presence of these autoantibodies is one of the criteria for the diagnosis and classification of SS, they are also sometimes seen in other systemic autoimmune diseases. In the last few decades, the knowledge of the prevalence of anti-Ro/SSA antibodies in various autoimmune diseases and symptoms has been expanded, and the clinical importance of these antibodies is increasing. Nonetheless, the pathological role of the antibodies is still poorly understood. In this paper, we summarize the milestones of the anti-Ro/SSA autoantibody system and provide new insights into the association between the autoantibodies and the pathogenesis of autoimmune diseases.

  12. Arctic Region Space Weather Customers and SSA Services

    DEFF Research Database (Denmark)

    Høeg, Per; Kauristi, Kirsti; Wintoft, Peter

    and communication can be established without errors resulting from Space Weather effects. An ESA project have identified and clarified, how the products of the four ESA Space Weather Expert Service Centres (SWE) in the ESA Space Situational Awareness Programme (SSA), can contribute to the requirements of SSA...... services in Arctic, and how new products and services need to be developed and implemented in the roadmap of SWE for Arctic region network services. An important element in the project is the end-user requirements and needs in the public and commercial sector. A detailed user-survey and interviews with key......-companies in the region have been performed. The outcome has been analysed in view of the present SWE system, and products and suggestions to a roadmap for the development of coming Arctic region SSA services, have been established....

  13. Preliminary approach of the MELiSSA loop energy balance

    Science.gov (United States)

    Poulet, Lucie; Lamaze, Brigitte; Lebrun, Jean

    Long duration missions, such as the establishment of permanent bases on the lunar surface or the travel to Mars, require a huge amount of life support consumables (e.g. food, water and oxygen). Current rockets are at the moment unable to launch such a mass from Earth. Consequently Regenerative Life Support Systems are necessary to sustain long-term manned space mission to increase recycling rates and so reduce the launched mass. Thus the European and Canadian research has been concentrating on the MELiSSA (Micro-Ecological Life Support System Alternative) project over the last 20 years. MELiSSA is an Environmental Controlled Life Support System (ECLSS), i.e. a closed regenerative loop inspired of a lake ecosystem. Using light as a source of energy, MELiSSA's goal is the recovery of food, water and oxygen from CO2 and organic wastes, using microorganisms and higher plants. The architecture of a ECLSS depends widely on the mission scenario. To compare several ECLSS architectures and in order to be able to evaluate them, ESA is developing a multi criteria evaluation tool: ALISSE (Advanced LIfe Support System Evaluator). One of these criteria is the energy needed to operate the ECLSS. Unlike other criteria like the physical mass, the energy criterion has not been investigated yet and needs hence a detailed analysis. It will consequently be the focus of this study. The main objective of the work presented here is to develop a dynamic tool able to estimate the energy balance for several configurations of the MELiSSA loop. The first step consists in establishing the energy balance using concrete figures from the MELiSSA Pilot Plant (MPP). This facility located at the Universitat Autonoma de Barcelona (UAB) is aimed at the ground demonstration of the MELiSSA loop. The MELiSSA loop is structured on several subsystems; each of them is characterized by supplies, exhausts and process reactions. For the purpose of this study (i.e. a generic tool) the solver EES (Engineering

  14. Number Albedo of Low-Energy Photons

    International Nuclear Information System (INIS)

    Ljubenov, V.; Simovic, R.; Markovic, S.

    2007-01-01

    Number albedo of water, aluminum and iron for incident photons in energy range from 20 keV to 100 keV is presented in this paper. Results are obtained through the Monte Carlo simulations of photon reflection by using the MCNP, FOTELP and PENELOPE computer codes. Calculated values are compared with the classical data published by B. P. Bulatov and his collaborators. Influence of the fluorescence yield to the photon number albedo of iron target is analyzed in detail. (author)

  15. Albedo Corrections for High Albedo Near Earth Objects Observed With Spitzer

    Science.gov (United States)

    Gustafsson, Annika; Trilling, David E.; Mommert, Michael; Hora, Joseph L.

    2017-10-01

    Thermal infrared observations are the most effective way to measure asteroid diameter and albedo. Major surveys like NEOWISE and NEOSurvey return a small fraction of objects with albedo values higher than that believed to exist in the near-Earth object (NEO) population. About 10% of Spitzer-observed NEOs have nominal albedo solutions greater than 0.5. There are many possible causes for these unrealistically high albedos, including thermal lightcurves (leading to a mis-estimate of asteroid diameter) or inaccurate absolute visual magnitudes (either from poor photometry or lightcurve effects). We present here the results of a ground-based optical photometric study of 36 high albedo NEOs from NEOSurvey (Trilling et al. 2016) using measurements from the Discovery Channel Telescope. Our findings indicate that uncertainty in the diameter has the most impact on the derived albedo of our targets, while the uncertainty in the H-magnitude and slope parameter have smaller effects. We supply corrected albedos for our target list, as well as a systematic offset dependent on the solar phase angle of the object (Mommert el al. 2017). These corrected albedo values will help constrain the albedo range in the population to better reflect its physical characteristics. This work is based in part on the observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.

  16. Accurate single-scattering simulation of ice cloud using the invariant-imbedding T-matrix method and the physical-geometric optics method

    Science.gov (United States)

    Sun, B.; Yang, P.; Kattawar, G. W.; Zhang, X.

    2017-12-01

    The ice cloud single-scattering properties can be accurately simulated using the invariant-imbedding T-matrix method (IITM) and the physical-geometric optics method (PGOM). The IITM has been parallelized using the Message Passing Interface (MPI) method to remove the memory limitation so that the IITM can be used to obtain the single-scattering properties of ice clouds for sizes in the geometric optics regime. Furthermore, the results associated with random orientations can be analytically achieved once the T-matrix is given. The PGOM is also parallelized in conjunction with random orientations. The single-scattering properties of a hexagonal prism with height 400 (in units of lambda/2*pi, where lambda is the incident wavelength) and an aspect ratio of 1 (defined as the height over two times of bottom side length) are given by using the parallelized IITM and compared to the counterparts using the parallelized PGOM. The two results are in close agreement. Furthermore, the integrated single-scattering properties, including the asymmetry factor, the extinction cross-section, and the scattering cross-section, are given in a completed size range. The present results show a smooth transition from the exact IITM solution to the approximate PGOM result. Because the calculation of the IITM method has reached the geometric regime, the IITM and the PGOM can be efficiently employed to accurately compute the single-scattering properties of ice cloud in a wide spectral range.

  17. 20 CFR 411.630 - Is SSA's decision final?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Is SSA's decision final? 411.630 Section 411.630 Employees' Benefits SOCIAL SECURITY ADMINISTRATION THE TICKET TO WORK AND SELF-SUFFICIENCY PROGRAM Ticket to Work Program Dispute Resolution Disputes Between Beneficiaries and Employment Networks § 411...

  18. 20 CFR 411.660 - Is SSA's decision final?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Is SSA's decision final? 411.660 Section 411.660 Employees' Benefits SOCIAL SECURITY ADMINISTRATION THE TICKET TO WORK AND SELF-SUFFICIENCY PROGRAM Ticket to Work Program Dispute Resolution Disputes Between Employment Networks and Program Managers § 411...

  19. Arctic sea ice albedo from AVHRR

    Science.gov (United States)

    Lindsay, R. W.; Rothrock, D. A.

    1994-01-01

    The seasonal cycle of surface albedo of sea ice in the Arctic is estimated from measurements made with the Advanced Very High Resolution Radiometer (AVHRR) on the polar-orbiting satellites NOAA-10 and NOAA-11. The albedos of 145 200-km-square cells are analyzed. The cells are from March through September 1989 and include only those for which the sun is more than 10 deg above the horizon. Cloud masking is performed manually. Corrections are applied for instrument calibration, nonisotropic reflection, atmospheric interference, narrowband to broadband conversion, and normalization to a common solar zenith angle. The estimated albedos are relative, with the instrument gain set to give an albedo of 0.80 for ice floes in March and April. The mean values for the cloud-free portions of individual cells range from 0.18 to 0.91. Monthly averages of cells in the central Arctic range from 0.76 in April to 0.47 in August. The monthly averages of the within-cell standard deviations in the central Arctic are 0.04 in April and 0.06 in September. The surface albedo and surface temperature are correlated most strongly in March (R = -0.77) with little correlation in the summer. The monthly average lead fraction is determined from the mean potential open water, a scaled representation of the temperature or albedo between 0.0 (for ice) and 1.0 (for water); in the central Arctic it rises from an average 0.025 in the spring to 0.06 in September. Sparse data on aerosols, ozone, and water vapor in the atmospheric column contribute uncertainties to instantaneous, area-average albedos of 0.13, 0.04, and 0.08. Uncertainties in monthly average albedos are not this large. Contemporaneous estimation of these variables could reduce the uncertainty in the estimated albedo considerably. The poor calibration of AVHRR channels 1 and 2 is another large impediment to making accurate albedo estimates.

  20. Evaluating Options for Civil Space Situational Awareness (SSA)

    Science.gov (United States)

    Lal, B.; Carioscia, S. A.

    In recent years, the number of active satellites and human-made orbital space debris has increased dramatically. An expansion of activities in space, as is currently being proposed by many commercial and international entities, is expected to further exacerbate this challenge. The 18th Space Control Squadron under the Department of Defense (DOD) United States Strategic Command provides space situational awareness (SSA) services to users outside the national security community at no cost. International and commercial users demand better SSA service than is currently feasible, and the demand comes at a time when DOD is under pressure to better prepare for and respond to growing space-based threats to national security. Concerned about the possibility of overextending across conflicting missions in a fiscally constrained environment, some DOD officials have publicly noted a desire to move SSA services not related to national security out of DOD purview. Responding to a request from the Federal Aviation Administration (FAA) Office of Commercial Space Transportation (AST), researchers at the Science and Technology Policy Institute (STPI) identified and evaluated potential approaches for providing SSA services for civil and commercial operations in space. In this paper, we summarize the report [1] and present the pros and cons of four approaches to the provision of civil SSA services in the United States: (1) maintaining status quo through continued provision by DOD; (2) provision by a civil government entity; (3) industry self-provision; and (4) provision by an international organization. Within the second approach, assuming the provision of SSA by a civil agency, STPI further identified and discussed four options: (1) civil agency service capability embedded within DOD; (2) independent civil service capability, using DOD software and systems; (3) independent civil service capability, using commercial software and systems; and (4) the government certifies non

  1. Non-traditional Sensor Tasking for SSA: A Case Study

    Science.gov (United States)

    Herz, A.; Herz, E.; Center, K.; Martinez, I.; Favero, N.; Clark, C.; Therien, W.; Jeffries, M.

    Industry has recognized that maintaining SSA of the orbital environment going forward is too challenging for the government alone. Consequently there are a significant number of commercial activities in various stages of development standing-up novel sensors and sensor networks to assist in SSA gathering and dissemination. Use of these systems will allow government and military operators to focus on the most sensitive space control issues while allocating routine or lower priority data gathering responsibility to the commercial side. The fact that there will be multiple (perhaps many) commercial sensor capabilities available in this new operational model begets a common access solution. Absent a central access point to assert data needs, optimized use of all commercial sensor resources is not possible and the opportunity for coordinated collections satisfying overarching SSA-elevating objectives is lost. Orbit Logic is maturing its Heimdall Web system - an architecture facilitating “data requestor” perspectives (allowing government operations centers to assert SSA data gathering objectives) and “sensor operator” perspectives (through which multiple sensors of varying phenomenology and capability are integrated via machine -machine interfaces). When requestors submit their needs, Heimdall’s planning engine determines tasking schedules across all sensors, optimizing their use via an SSA-specific figure-of-merit. ExoAnalytic was a key partner in refining the sensor operator interfaces, working with Orbit Logic through specific details of sensor tasking schedule delivery and the return of observation data. Scant preparation on both sides preceded several integration exercises (walk-then-run style), which culminated in successful demonstration of the ability to supply optimized schedules for routine public catalog data collection – then adapt sensor tasking schedules in real-time upon receipt of urgent data collection requests. This paper will provide a

  2. SURFACE ALBEDO AND SPECTRAL VARIABILITY OF CERES

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian-Yang; Reddy, Vishnu; Corre, Lucille Le; Sykes, Mark V.; Prettyman, Thomas H. [Planetary Science Institute, 1700 E. Ft. Lowell Road, Suite 106, Tucson, AZ 85719 (United States); Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael [Max Planck Institute for Solar System Research, Göttingen (Germany); Izawa, Matthew R. M.; Cloutis, Edward A. [University of Winnipeg, Winnipeg, Manitoba (Canada); Carsenty, Uri; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Schröder, Stefan E. [German Aerospace Center (DLR), Institute of Planetary Research, Berlin (Germany); Castillo-Rogez, Julie C. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Schenk, Paul [Lunar and Planetary Institute, Houston, TX 77058 (United States); Williams, David A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Smith, David E. [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zuber, Maria T. [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km{sup 2}, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  3. The Albedo of Kepler's Small Worlds

    Science.gov (United States)

    Jansen, Tiffany; Kipping, David

    2018-01-01

    The study of exoplanet phase curves has been established as a powerful tool for measuring the atmospheric properties of other worlds. To first order, phase curves have the same amplitude as occultations, yet far greater temporal baselines enabling substantial improvements in sensitivity. Even so, only a relatively small fraction of Kepler planets have detectable phase curves, leading to a population dominated by hot-Jupiters. One way to boost sensitivity further is to stack different planets of similar types together, giving rise to an average phase curve for a specific ensemble. In this work, we measure the average albedo, thermal redistribution efficiency, and greenhouse boosting factor from the average phase curves of 115 Neptunian and 50 Terran (solid) worlds. We construct ensemble phase curve models for both samples accounting for the reflection and thermal components and regress our models assuming a global albedo, redistribution factor and greenhouse factor in a Bayesian framework. We find modest evidence for a detected phase curve in the Neptunian sample, although the albedo and thermal properties are somewhat degenerate meaning we can only place an upper limit on the albedo of Ag < 0.23 and greenhouse factor of f < 1.40 to 95% confidence. As predicted theoretically, this confirms hot-Neptunes are darker than Neptune and Uranus. Additionally, we place a constraint on the albedo of solid, Terran worlds of Ag < 0.42 and f < 1.60 to 95% confidence, compatible with a dark Lunar-like surface.

  4. The Ro/SSA Complex in Systemic Lupus Erythematosus Patients

    OpenAIRE

    Do Nascimento, Noelle Mariane

    2017-01-01

    In this work the involved mechanisms between Ro/SSA complex, composed also by the tripartite motif 21 (TRIM21alpha) and trove domain 2 (TROVE2) proteins, with respect to systemic lupus erythematosus (SLE) autoantibodies is studied. The work is divided in three chapters: I- In vitro and in silico analysis of the molecular recognition between lupus autoantibodies and TRIM21alpha Fc Receptor ; II- In vitro evidence of bipolar-bridged immune TROVE2 complexes in the pathogenesis of systemic lupus ...

  5. Systematic Sustainability Assessment (SSA) Tool for Hydroelectric Project in Malaysia

    Science.gov (United States)

    Turan, Faiz Mohd; Johan, Kartina

    2017-08-01

    Sustainably developed and managed hydropower has enormous potential to contribute to global sustainability goals. It is known that hydroelectricity contributing small amounts to greenhouse gas emissions and other atmospheric pollutants. However, developing the remaining hydroelectric potential offers many challenges, and public pressure and expectations on the environmental and social performance of hydroelectric tend to increase over time. This paper aims to develop Systematic Sustainability Assessment (SSA) Tool that promotes and guides more sustainable hydroelectric projects in the context of Malaysia. The proposed SSA tool which not only provide a quality and quantitative report of sustainability performance but also act as Self-Assessment Report (SAR) to provide roadmap to achieve greater level of sustainability in project management for continuous improvement. It is expected to provide a common language that allow government, civil society, financial institutions and the hydroelectric sector to talk about and evaluate sustainability issues. The advantage of SSA tool is it can be used at any stage of hydroelectric development, from the earliest planning stages right through to operation.

  6. NEOWISE DIAMETERS AND ALBEDOS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by...

  7. Variability of soil moisture and its relationship with surface albedo ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 119; Issue 4. Variability of soil moisture and its relationship with surface albedo and soil thermal ... The diurnal variation of surface albedo appears as a U-shaped curve on sunny days. Surface albedo decreases with the increase of solar elevation angle, and it tends ...

  8. Albedo decline on Greenland's Mittivakkat Gletscher in a warming climate

    DEFF Research Database (Denmark)

    Mernild, Sebastian H; Malmros, Jeppe K.; Yde, Jacob Clement

    2015-01-01

    balance year (EBY), MG's AWS observed bare ice albedo reached ∼0.3 only just exceeding values observed for proglacial bedrock (∼0.2). The analysis reveals negative mean trends in the MODIS-derived MG EBY albedo for the period 2000–2013 with a significant decline in mean glacier-wide albedo of 0...

  9. BOREAS TE-12 SSA Leaf Water Potential Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Walter-Shea, Elizabeth A.; Mesarch, Mark A.; Chen, L.; Yang, Litao

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-12 (Terrestrial Ecology) team collected water potential data in 1993 and 1994 from aspen, jack pine, and black spruce leaves/needles. Collections were made at the Southern Study Area Nipawin Fen Site (SSA FEN), Young Jack Pine (YJP), Young Aspen (YA), Old Aspen (OA), and Old Black Spruce (OBS) sites. Measurements were made using a pressure chamber on a platform in the field. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  10. ESA's SSA Programme: Activities in Space Surveillance and Tracking

    Science.gov (United States)

    Flohrer, T.; Krag, H.

    Today, satellites and space-based systems are indispensable for the provision of critical services. Understanding and forecasting the space environment, especially space weather, near-Earth objects, and the population of space debris is needed to protect our space-based infrastructure. The rapidly growing number of smaller satellites and maturing plans for deploying large constellations of satellites further increase the need for reliable and timely information on the space object population. Since 2009 the European Space Agency (ESA) has been undertaking an Space Situational Awareness (SSA) Program with three segments Space Weather (SWE), Near Earth Objects (NEO) and Space Surveillance and Tracking (SST). Period 3 of the program has been approved at the ESA Ministerial Council in December 2016 for a 3-year period starting 2017. A total of 19 member states of ESA participate in the SSA program, of which 11 subscribed to the SST segment. In SST, the development of the technologies for detection, cataloguing and follow-up of space objects, and of the derived applications for conjunction event prediction, re-entry predictions, and fragmentation event detection are considered as the first important steps towards an European SST capability. To achieve this goal, ESA is focusing on research and development, supporting national initiatives, and staying complementary with other European approaches in SST. It is expected that in Europe a demand for larger, cross-national SST components and technology developments arises to ensure interoperability of systems. Examples of planned activities are space-based SST sensors, processing software, facilitating data exchange mechanisms, and common data processing techniques and formats. With the activities of the SSA program ESA’s expertise will be further exploited in supporting the research, development, and coordination of space-related technologies in a multinational environment, and in assessing and maturing the relevant

  11. Modeling Earth Albedo for Satellites in Earth Orbit

    DEFF Research Database (Denmark)

    Bhanderi, Dan; Bak, Thomas

    2005-01-01

    Many satellite are influences by the Earthøs albedo, though very few model schemes exist.in order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate...... with as much as 20 deg. Digital Sun sensors with Earth albedo correction in hardware exist, but are expensive. In addition, albedo estimates are necessary in thermal calculations and power budgets. We present a modeling scheme base4d on Eartht reflectance, measured by NASA's Total Ozone Mapping Spectrometer......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view...

  12. BOREAS TE-1 SSA-Fen Soil Profile Nutrient Data

    Science.gov (United States)

    Papagno, Andrea; Anderson, Darwin; Newcomer, Jeffrey A. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall traniect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains soil profile measurements of various nutrients at the SSA-Fen site. The data were collected from 23-May to 21-Oct- 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  13. MODIS/Terra+Aqua BRDF/Albedo Black Sky Albedo Shortwave Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D51 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Black Sky Albedo near shortwave broadband data set is a daily 16-day...

  14. MODIS/Terra+Aqua BRDF/Albedo Black Sky Albedo VIS Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D49 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Black Sky Albedo visible broadband data set is a daily 16-day...

  15. OMI/Aura Multi-wavelength Aerosol Optical Depth and Single Scattering Albedo L3 1 day Best Pixel in 0.25 degree x 0.25 degree V3 (OMAEROe) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI science team produces this Level-3 Aura/OMI Global Aerosol Data Products OMAEROe (0.25deg Lat/Lon grids). The OMAEROe product selects best aerosol value from...

  16. OMI/Aura Multi-wavelength Aerosol Optical Depth and Single Scattering Albedo Daily L2 Global 0.25x0.25 deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The second release of Collection 3 OMI/Aura level-2G daily global gridded (0.25x0.25 deg) Aerosol data product OMAEROG (Version 003 has been made available to the...

  17. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo Daily L2 Global 0.25x0.25 deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI-Aura level-2G daily global gridded (0.25x0.25 deg) near-UV Aerosol data product OMAERUVG based on the enhanced algorithm is available from the NASA Goddard...

  18. OMI/Aura Level 2 Near UV Aerosol Optical Depth and Single Scattering Albedo 200-m swath subset along CloudSat track V003 (OMAERUV_CPR) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a CloudSat-collocated subset of the original OMI product OMAERUV, for the purposes of the A-Train mission. The goal of the subset is to select and return OMI...

  19. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo Daily L2 Global Gridded 0.25 degree x 0.25 degree V3 (OMAERUVG) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This Level-2G daily global gridded product OMAERUVG is based on the pixel level OMI Level-2 AERUV product OMAERUV. This Level-2G daily global gridded product...

  20. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo L3 1 day 0.25 degree x 0.25 degree V3 (OMAERUVd) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI science team produces this Level-3 daily global gridded product OMAERUVd (1 deg Lat/Lon grids). The OMAERUVd product is produced with all data pixels that...

  1. OMI/Aura Multi-wavelength Aerosol Optical Depth and Single Scattering Albedo Daily L3 Global 0.25x0.25 deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI science team produces two Level-3 Aura/OMI Global Aerosol Data Products OMAERUVd (1deg Lat/Lon grids) and OMAEROe (0.25deg Lat/Lon grids). The OMAERUVd...

  2. MELiSSA Food Characterization general approach and current status

    Science.gov (United States)

    Weihreter, Martin; Chaerle, Laury; Secco, Benjamin; Molders, Katrien; van der Straeten, Dominique; Duliere, Eric; Pieters, Serge; Maclean, Heather; Dochain, Denis; Quinet, Muriel; Lutts, Stanley; Graham, Thomas; Stasiak, Michael; Rondeau Vuk, Theresa; Zheng, Youbin; Dixon, Mike; Laniau, Martine; Larreture, Alain; Timsit, Michel; Aronne, Giovanna; Barbieri, Giancarlo; Buonomo, Roberta; Veronica; Paradiso, Roberta; de Pascale, Stafania; Galbiati, Massimo; Troia, A. R.; Nobili, Matteo; Bucchieri, Lorenzo; Page, Valérie; Feller, Urs; Lasseur, Christophe

    Higher plants play an important role in closed ecological life support systems as oxygen pro-ducers, carbon dioxide and water recyclers, and as a food source. For an integration of higher plant chambers into the MELiSSA (Micro Ecological Life Support System Alternative) loop, a detailed characterization and optimization of the full food production and preparation chain is needed. This implies the prediction and control of the nutritional quality of the final products consumed by the crew, the prediction of the wastes quality and quantity produced along the chain for further waste treatment (MELiSSA waste treatment) and the optimization of overall efficiencies. To reach this goal several issues have to be studied in an integrated manner: the physiological responses of crops to a range of environmental parameters, crop yield efficiencies and respective ratio and composition of edible and inedible biomass, the processability and storability of the produced food and last but not least composition of wastes in view of further degradation (fiber content). Within the Food Characterization (FC) project several compar-ative plant growth bench tests were carried out to obtain preliminary data regarding these aspects. Four pre-selected cultivars of each of the four energy-rich crops with worldwide usage -wheat, durum wheat, potato and soybean -were grown under well-characterized environmental conditions. The different cultivars of each species are screened for their performance in view of a closed loop application by parameter ranking. This comprises the characterization of edi-ble/inedible biomass ratio, nutritional quality, processability and overall performance under the specific conditions of hydroponic cultivation and artificial illumination. A second closely linked goal of the FC project is to develop a mechanistic physiological plant model, which will ease the integration of higher plants compartments in the MELiSSA concept by virtue of its predictive abilities

  3. Human Decision Processes: Implications for SSA Support Tools

    Science.gov (United States)

    Picciano, P.

    2013-09-01

    Despite significant advances in computing power and artificial intelligence (AI), few critical decisions are made without a human decision maker in the loop. Space Situational Awareness (SSA) missions are both critical and complex, typically adhering to the human-in-the-loop (HITL) model. The collection of human operators injects a needed diversity of expert knowledge, experience, and authority required to successfully fulfill SSA tasking. A wealth of literature on human decision making exists citing myriad empirical studies and offering a varied set of prescriptive and descriptive models of judgment and decision making (Hastie & Dawes, 2001; Baron, 2000). Many findings have been proven sufficiently robust to allow information architects or system/interface designers to take action to improve decision processes. For the purpose of discussion, these concepts are bifurcated in two groups: 1) vulnerabilities to mitigate, and 2) capabilities to augment. These vulnerabilities and capabilities refer specifically to the decision process and should not be confused with a shortcoming or skill of a specific human operator. Thus the framing of questions and orders, the automated tools with which to collaborate, priming and contextual data, and the delivery of information all play a critical role in human judgment and choice. Evaluating the merits of any decision can be elusive; in order to constrain this discussion, ‘rational choice' will tend toward the economic model characteristics such as maximizing utility and selection consistency (e.g., if A preferred to B, and B preferred to C, than A should be preferred to C). Simple decision models often encourage one to list the pros and cons of a decision, perhaps use a weighting schema, but one way or another weigh the future benefit (or harm) of making a selection. The result (sought by the rationalist models) should drive toward higher utility. Despite notable differences in researchers' theses (to be discussed in the full

  4. Albedo and transmittance of inhomogeneous stratus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.E.; Kasyanov, E.I.; Titov, G.A. [Institute of Atmospheric Optics, Tomsk (Russian Federation)] [and others

    1996-04-01

    A highly important topic is the study of the relationship between the statistical parameters of optical and radiative charactertistics of inhomogeneous stratus clouds. This is important because the radiation codes of general circulation models need improvement, and it is important for geophysical information. A cascade model has been developed at the Goddard Space Flight Center to treat stratocumulus clouds with the simplest geometry and horizontal fluctuations of the liquid water path (optical thickness). The model evaluates the strength with which the stochastic geometry of clouds influences the statistical characteristics of albedo and the trnasmittance of solar radiation.

  5. Large-scale simulations of snow albedo masking by forests

    OpenAIRE

    Essery, Richard

    2013-01-01

    Comparisons between climate models have found large differences in predictions for the albedo of forested regions with snow cover, leading to uncertainty in the strength of snow albedo feedbacks on climate change predicted by these models. To explore this uncertainty, three commonly used methods for calculating the albedo of vegetated surfaces are compared, taking observed snow and vegetation distributions as inputs. Surprisingly, all three methods produce similar results and compare reasonab...

  6. MODIS/Terra+Aqua BRDF/Albedo Albedo Daily L3 Global - 500m V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS MCD43A3 Version 6 Albedo Model data set is a daily 16-day product. The Julian date in the granule ID of each specific file represents the 9th day of the 16...

  7. 20 CFR 411.330 - How will SSA evaluate an EN's performance?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How will SSA evaluate an EN's performance? 411.330 Section 411.330 Employees' Benefits SOCIAL SECURITY ADMINISTRATION THE TICKET TO WORK AND SELF-SUFFICIENCY PROGRAM Employment Networks § 411.330 How will SSA evaluate an EN's performance? (a) We will...

  8. 77 FR 43639 - Privacy Act of 1974, as Amended; Computer Matching Program (Social Security Administration (SSA...

    Science.gov (United States)

    2012-07-25

    ...)/Department of Veterans Affairs (VA), Veterans Benefits Administration (VBA))--Match Number 1008 AGENCY: SSA... of an existing computer matching program that we are currently conducting with VA/VBA. DATES: We will... Benefits Administration (VBA) A. Participating Agencies SSA and VA/VBA. B. Purpose of the Matching Program...

  9. 77 FR 54943 - Privacy Act of 1974, as Amended; Computer Matching Program (Social Security Administration (SSA...

    Science.gov (United States)

    2012-09-06

    ...)/Department of Veterans Affairs (VA), Veterans Benefits Administration (VBA))--Match Number 1309 AGENCY: SSA... of an existing computer matching program that we are currently conducting with VA/VBA. DATES: We will... Benefits Administration (VBA). A. Participating Agencies SSA and VA/VBA. B. Purpose of the Matching Program...

  10. Isolated anti-Ro/SSA thrombocytopenia: a rare feature of neonatal ...

    African Journals Online (AJOL)

    We report a rare case of isolated thrombocytopenia related to anti-Ro/SSA antibodies. The mother was followed for unlabeled familial thrombocytopenia. The mother had positive anti-Ro/SSA antibodies. She was asymptomatic without skin lesions or other criteria neither of systemic lupus erythematosus nor other connective ...

  11. Albedo of the ice covered Weddell and Bellingshausen Seas

    OpenAIRE

    Weiss, A. I.; King, J. C.; Lachlan-Cope, T. A.; Ladkin, R. S.

    2012-01-01

    This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo o...

  12. Enhancement of the MODIS Daily Snow Albedo Product

    Science.gov (United States)

    Hall, Dorothy K.; Schaaf, Crystal B.; Wang, Zhuosen; Riggs, George A.

    2009-01-01

    The MODIS daily snow albedo product is a data layer in the MOD10A1 snow-cover product that includes snow-covered area and fractional snow cover as well as quality information and other metadata. It was developed to augment the MODIS BRDF/Albedo algorithm (MCD43) that provides 16-day maps of albedo globally at 500-m resolution. But many modelers require daily snow albedo, especially during the snowmelt season when the snow albedo is changing rapidly. Many models have an unrealistic snow albedo feedback in both estimated albedo and change in albedo over the seasonal cycle context, Rapid changes in snow cover extent or brightness challenge the MCD43 algorithm; over a 16-day period, MCD43 determines whether the majority of clear observations was snow-covered or snow-free then only calculates albedo for the majority condition. Thus changes in snow albedo and snow cover are not portrayed accurately during times of rapid change, therefore the current MCD43 product is not ideal for snow work. The MODIS daily snow albedo from the MOD10 product provides more frequent, though less robust maps for pixels defined as "snow" by the MODIS snow-cover algorithm. Though useful, the daily snow albedo product can be improved using a daily version of the MCD43 product as described in this paper. There are important limitations to the MOD10A1 daily snow albedo product, some of which can be mitigated. Utilizing the appropriate per-pixel Bidirectional Reflectance Distribution Functions (BRDFs) can be problematic, and correction for anisotropic scattering must be included. The BRDF describes how the reflectance varies with view and illumination geometry. Also, narrow-to-broadband conversion specific for snow on different surfaces must be calculated and this can be difficult. In consideration of these limitations of MOD10A1, we are planning to improve the daily snow albedo algorithm by coupling the periodic per-pixel snow albedo from MCD43, with daily surface ref|outanoom, In this paper, we

  13. Measurements of spectral snow albedo at Neumayer, Antarctica

    OpenAIRE

    Wuttke Sigrid; Seckmeyer G; König-Langlo Gert

    2006-01-01

    Spectral albedo in high resolution, from 290 to 1050 nm, has been measured at Neumayer, Antarctica, (70°39' S, 8°15' W) during the austral summer 2003/2004. At 500 nm, the spectral albedo nearly reaches unity, with slightly lower values below and above 500 nm. Above 600 nm, the spectral albedo decreases to values between 0.45 and 0.75 at 1000 nm. For one cloudless case an albedo up to 1.01 at 500 nm could be determined. This can be explained by the larger directional...

  14. LUNAR TERRAIN AND ALBEDO RECONSTRUCTION FROM APOLLO IMAGERY

    Data.gov (United States)

    National Aeronautics and Space Administration — LUNAR TERRAIN AND ALBEDO RECONSTRUCTION FROM APOLLO IMAGERY ARA V NEFIAN*, TAEMIN KIM, MICHAEL BROXTON, AND ZACH MORATTO Abstract. Generating accurate three...

  15. Spacecraft Attitude Determination with Earth Albedo Corrected Sun Sensor Measurements

    DEFF Research Database (Denmark)

    Bhanderi, Dan

    This thesis focuses on advanced modeling of the Earth albedo experienced by satellites in Earth orbit. The model of the Earth albedo maintains directional information of the Earth albedo irradiance from each partition on the Earth surface. This allows enhanced modeling of Sun sensor current outputs......-Method, Extended Kalman Filter, and Unscented Kalman Filter algorithms are presented and the results are compared. Combining the Unscented Kalman Filter with Earth albedo and enhanced Sun sensor modeling allows for three-axis attitude determination from Sun sensor only, which previously has been perceived...

  16. Arrhythmogenicity of Anti-Ro/SSA Antibodies in Patients With Torsades de Pointes.

    Science.gov (United States)

    Lazzerini, Pietro Enea; Yue, Yuankun; Srivastava, Ujala; Fabris, Frank; Capecchi, Pier Leopoldo; Bertolozzi, Iacopo; Bacarelli, Maria Romana; Morozzi, Gabriella; Acampa, Maurizio; Natale, Mariarita; El-Sherif, Nabil; Galeazzi, Mauro; Laghi-Pasini, Franco; Boutjdir, Mohamed

    2016-04-01

    In patients with autoimmune disease, anti-Ro/SSA antibodies (anti-Ro/SSA) are responsible for a novel autoimmune-associated long-QT syndrome by targeting the hERG potassium channel and inhibiting the related current (IKr). Because anti-Ro/SSA are also present in a significant proportion of healthy subjects and may be associated with torsades de pointes (TdP) arrhythmia, we tested the hypothesis that anti-Ro/SSA may represent a silent risk factor in patients developing TdP. Twenty-five consecutive patients who experienced TdP were prospectively collected independent of ongoing therapies and concomitant diseases. Anti-Ro/SSA were detected by fluoroenzyme immunoassay, immuno-Western blotting, and line-blot immunoassay. Purified IgGs from anti-Ro/SSA-positive and anti-Ro/SSA-negative patients were tested on IKr using HEK293 cells stably expressing the hERG channel. As expected, in TdP patients, many known corrected QT interval-prolonging risk factors were simultaneously present, including hypokalemia that was the most common (52%). Anti-Ro/SSA were present in 60% of the subjects, mostly the anti-Ro/SSA-52-kD subtype detected by immuno-Western blotting only. A history of autoimmune disease was found in only 2 of anti-Ro/SSA-positive patients. Experimental data demonstrated that purified anti-Ro/SSA-positive IgGs significantly inhibited IKr and cross reacted with hERG-channel proteins. Moreover, anti-Ro/SSA-positive sera exhibited high reactivity with a peptide corresponding to the hERG-channel pore-forming region. Anti-Ro/SSA may represent a clinically silent novel risk factor for TdP development via an autoimmune-mediated electrophysiological interference with the hERG channel. We propose that TdP patients may benefit from specific anti-Ro/SSA testing even in the absence of autoimmune diseases as immunomodulating therapies may be effective in shortening corrected QT interval and reducing TdP recurrence risk. © 2016 American Heart Association, Inc.

  17. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    OpenAIRE

    Y. Liu; W. Wu; M. P. Jensen; T. Toto

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

  18. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    OpenAIRE

    Y. Liu; W. Wu; M. P. Jensen; T. Toto

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction...

  19. 78 FR 16564 - Privacy Act of 1974, as Amended; Computer Matching Program (SSA/Office of Personnel Management...

    Science.gov (United States)

    2013-03-15

    ... (SSN) verification to our Master Files of SSN Holders and SSN Applications. The Federal Register designation for the SSA file is Master Files of SSN Holders and SSN Applications, SSA/OSR, 60-0058. Those...

  20. Measurements of spectral snow albedo at Neumayer, Antarctica

    Directory of Open Access Journals (Sweden)

    S. Wuttke

    2006-03-01

    Full Text Available Spectral albedo in high resolution, from 290 to 1050 nm, has been measured at Neumayer, Antarctica, (70°39' S, 8°15' W during the austral summer 2003/2004. At 500 nm, the spectral albedo nearly reaches unity, with slightly lower values below and above 500 nm. Above 600 nm, the spectral albedo decreases to values between 0.45 and 0.75 at 1000 nm. For one cloudless case an albedo up to 1.01 at 500 nm could be determined. This can be explained by the larger directional component of the snow reflectivity for direct incidence, combined with a slightly mislevelled sensor and the snow surface not being perfectly horizontal. A possible explanation for an observed decline in albedo is an increase in snow grain size. The theoretically predicted increase in albedo with increasing solar zenith angle (SZA could not be observed. This is explained by the small range of SZA during albedo measurements, combined with the effect of changing snow conditions outweighing the effect of changing SZA. The measured spectral albedo serves as input for radiative transfer models, describing radiation conditions in Antarctica.

  1. The albedo of snow for partially cloudy skies

    Science.gov (United States)

    Choudhury, B. J.; Chang, A. T. C.

    1980-01-01

    The input parameters of the model are atmospheric precipitable water, ozone content, turbidity, cloud optical thickness, size and shape of ice crystal of snow and surface pressure. The model outputs spectral and integrated solar flux snow reflectance as a function of solar elevation and fractional cloudcover. The model is illustrated using representative parameters for the Antarctic coastal regions. The albedo for a clear sky depends inversely on the solar elevation. At high elevation the albedo depends primarily upon the grain size; at low elevation this dependence is on grain size and shape. The gradient of the albedo-elevation curve increases as the grains get larger and faceted. The albedo for a dense overcast is a few percent higher than the clear sky albedo at high elevations. A simple relation between the grain size and the overcast albedo is obtained. For a set of grain size and shape, the albedo matrices (the albedo as a function of solar elevation and fractional cloudcover) are tabulated.

  2. Variability of soil moisture and its relationship with surface albedo ...

    Indian Academy of Sciences (India)

    30 N latitude) are used to study the diurnal, monthly and seasonal soil moisture variations. The effect of rainfall on diurnal and seasonal soil moisture is discussed. We have investigated relationships of soil moisture with sur- face albedo and soil thermal diffusivity. The diurnal variation of surface albedo appears as a.

  3. The effect of pulverization on the albedo of lunar rocks

    NARCIS (Netherlands)

    Minnaert, Marcel Gilles Jozef

    1969-01-01

    Measures of the albedo under full-moon conditions have been made on two samples of very dark rocks, pulverized and sieved so as to obtain powders of different grain size. Below a size of 0.05 mm the albedo suddenly increases, obviously because the individual grains become transparent. By a rough

  4. NEOWISE REACTIVATION MISSION YEAR TWO: ASTEROID DIAMETERS AND ALBEDOS

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R.; Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Bauer, J.; Kramer, E. A.; Masiero, J.; Sonnett, S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States); Wright, E. L., E-mail: cnugent@ipac.caltech.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  5. Use of wrist albedo neutron dosimeters

    International Nuclear Information System (INIS)

    Hankins, D.E.

    1983-01-01

    We are developing a wrist dosimeter that can be used to measure the exposure at the wrist to x-rays, gamma rays, beta-particles, thermal neutrons and fast neutrons. It consists of a modified Hankins Type albedo neutron dosimeter and also contains three pieces of CR-39 plastic. ABS plastic in the form of an elongated hemisphere provides the beta and low energy x-ray shielding necessary to meet the requirement of depth dose measurements at 1 cm. The dosimeter has a beta window located in the side of the hemisphere oriented towards an object being held in the hands. A TLD 600 is positioned under the 1 cm thick ABS plastic and is used to measure the thermal neutron dose. At present we are using Velcro straps to hold the dosimeter on the inside of the wrist. 9 figures

  6. Global color and albedo variations on Io

    Science.gov (United States)

    McEwen, A.S.

    1988-01-01

    Three multispectral mosaics of Io have been produced from Voyager imaging data: a global mosaic from each of the Voyager 1 and Voyager 2 data sets and a high-resolution mosaic of the region surrounding the volcano Ra Patera. The mosaics are maps of normal albedo and color in accurate geometric map formats. Io's photometric behavior, mapped with a two-image technique, is spatially variable, especially in the bright white areas. The disk-integrated color and albedo of the satellite have been remarkably constant over recent decades, despite the volcanic activity and the many differences between Voyager 1 and 2 images (acquired just 4 months apart). This constancy is most likely due to the consistent occurrence of large Pele-type plumes with relatively dark, red deposits in the region from long 240 to 360??. A transient brightening southeast of Pele during the Voyager 1 encounter was probably due to real changes in surface and/or atmospheric materials, rather than to photometric behavior. The intrinsic spectral variability of Io, as seen in a series of two-dimensional histograms of the multispectral mosaics, consists of continuous variation among three major spectral end members. The data were mapped into five spectral units to compare them with laboratory measurements of candidate surface materials and to show the planimetric distributions. Unit 1 is best fit by the spectral reflectance of ordinary elemental sulfur, and it is closely associated with the Peletype plume deposits. Unit 2 is strongly confined to the polar caps above about latitude ??50??, but its composition is unknown. Unit 5 is probably SO2 with relatively minor contamination; it is concentrated in the equatorial region and near the long-lived Prometheus-type plumes. Units 3 and 4 are gradational between units 1 and 5. In addition to SO2 and elemental sulfur, other plausible components of the surface are polysulfur oxides, FeCl2, Na2S, and NaHS. ?? 1988.

  7. Fire disturbance effects on land surface albedo in Alaskan tundra

    Science.gov (United States)

    French, Nancy H. F.; Whitley, Matthew A.; Jenkins, Liza K.

    2016-03-01

    The study uses satellite Moderate Resolution Imaging Spectroradiometer albedo products (MCD43A3) to assess changes in albedo at two sites in the treeless tundra region of Alaska, both within the foothills region of the Brooks Range, the 2007 Anaktuvuk River Fire (ARF) and 2012 Kucher Creek Fire (KCF). Results are compared to each other and other studies to assess the magnitude of albedo change and the longevity of impact of fire on land surface albedo. In both sites there was a marked decrease of albedo in the year following the fire. In the ARF, albedo slowly increased until 4 years after the fire, when it returned to albedo values prior to the fire. For the year immediately after the fire, a threefold difference in the shortwave albedo decrease was found between the two sites. ARF showed a 45.3% decrease, while the KCF showed a 14.1% decrease in shortwave albedo, and albedo is more variable in the KCF site than ARF site 1 year after the fire. These differences are possibly the result of differences in burn severity of the two fires, wherein the ARF burned more completely with more contiguous patches of complete burn than KCF. The impact of fire on average growing season (April-September) surface shortwave forcing in the year following fire is estimated to be 13.24 ± 6.52 W m-2 at the ARF site, a forcing comparable to studies in other treeless ecosystems. Comparison to boreal studies and the implications to energy flux are discussed in the context of future increases in fire occurrence and severity in a warming climate.

  8. Simulations of tropical rainforest albedo: is canopy wetness important?

    Directory of Open Access Journals (Sweden)

    Silvia N.M. Yanagi

    Full Text Available Accurate information on surface albedo is essential for climate modelling, especially for regions such as Amazonia, where the response of the regional atmospheric circulation to the changes on surface albedo is strong. Previous studies have indicated that models are still unable to correctly reproduce details of the seasonal variation of surface albedo. Therefore, it was investigated the role of canopy wetness on the simulated albedo of a tropical rainforest by modifying the IBIS canopy radiation transfer code to incorporate the effects of canopy wetness on the vegetation reflectance. In this study, simulations were run using three versions of the land surface/ecosystem model IBIS: the standard version, the same version recalibrated to fit the data of albedo on tropical rainforests and a modified version that incorporates the effects of canopy wetness on surface albedo, for three sites in the Amazon forest at hourly and monthly scales. The results demonstrated that, at the hourly time scale, the incorporation of canopy wetness on the calculations of radiative transfer substantially improves the simulations results, whereas at the monthly scale these changes do not substantially modify the simulated albedo.

  9. Surface albedo measurements in Mexico City metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Castro, T; Mar, B; Longoria, R; Ruiz Suarez, L. G [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico); Morales, L [Instituto de Geografia, UNAM, Mexico, D.F. (Mexico)

    2001-04-01

    Optical and thermal properties of soils are important input data for the meteorological and photochemical modules of air quality models. As development of these models increase on spatial resolution good albedo data become more important. In this paper measurements of surface albedo of UV (295-385 nm) and visible (450-550 nm) radiation are reported for different urban and rural surfaces in the vicinity of Mexico City. It was found for the downtown zone and average albedo value of 0.05 which is in very good agreement with reported values for urban surfaces. Our albedo values measured in UV region for grey cement and green grass are of 0.10 and 0.009, respectively, and quite similar to those found at the literature of 0.11 and 0.008 for those type of surfaces. [Spanish] Las propiedades opticas y termicas de suelos son datos importantes para los modulos meteorologicos y fotoquimicos de los modelos de calidad del aire. Conforme aumenta la resolucion espacial del modelo se vuelve mas importante contar con buenos datos de albedo. En este articulo se presentan mediciones de albedo superficial de radiacion Ultravioleta (295-385 nm) y visible (450-550 nm) para diferentes superficies urbanas. Los valores medidos de albedo en la region UV para cemento gris y pasto verde son de 0.10 y 0.009, respectivamente, y son muy similares a los reportados en la literatura, 0.11 y 0.008 para este tipo de superficies.

  10. VBA SSA Acc To Fed Rec Online (SAFRO) - Also known as Veterans Benefit Administration Query (VBAQ).

    Data.gov (United States)

    Social Security Administration — The purpose of this query is to provide SSA field office personnel with real-time access to military discharge data from the VA BIRLS database. This information is...

  11. Shock Hazard Prevention through Self-Healing Insulative Coating on SSA Metallic Bearings, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The space suit assembly (SSA) contains metallic bearings at the wrist, neck, and waist, which are exposed to space environment, and pose a potential shock hazard....

  12. Resonance assignments for the substrate binding domain of Hsp70 chaperone Ssa1 from Saccharomyces cerevisiae.

    Science.gov (United States)

    Hu, Wanhui; Wu, Huiwen; Zhang, Hong; Gong, Weibin; Perrett, Sarah

    2015-10-01

    Hsp70 chaperone proteins play crucial roles in the cell. Extensive structural and functional studies have been performed for bacterial and mammalian Hsp70s. Ssa1 from Saccharomyces cerevisiae is a member of the Hsp70 family. In vivo and biochemical studies on Ssa1 have revealed that it regulates prion propagation and the cell cycle. However, no structural data has been obtained for Ssa1 up to now. Here we report the almost complete (96 %) (1)H, (13)C, (15)N backbone and side chain NMR assignment of the 18.8 kDa Ssa1 substrate binding domain. The construct includes residues 382-554, which corresponds to the entire substrate binding domain and two following α-helices in homologous structures. The secondary structure predicted from the assigned chemical shifts is consistent with that of homologous Hsp70 substrate binding domains.

  13. BOREAS RSS-08 SSA IFC-3 Digitized Stereo Imagery at the OBS, OA, and OJP Sites

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The RSS08 team acquired stereo photography from the double-scaffold towers at the Southern Study Area (SSA), Old Black Spruce (OBS), Old Aspen (OA), and...

  14. BOREAS RSS-08 SSA IFC-3 Digitized Stereo Imagery at the OBS, OA, and OJP Sites

    Data.gov (United States)

    National Aeronautics and Space Administration — The RSS08 team acquired stereo photography from the double-scaffold towers at the Southern Study Area (SSA), Old Black Spruce (OBS), Old Aspen (OA), and Old Jack...

  15. BOREAS TE-18 Landsat TM Physical Classification Image of the SSA

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The objective of this classification is to provide BOREAS investigators with a data product that characterizes the land cover of the SSA. A Landsat-5 TM...

  16. Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers

    Directory of Open Access Journals (Sweden)

    J. E. Box

    2012-08-01

    Full Text Available Greenland ice sheet mass loss has accelerated in the past decade responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the ablation area. Using satellite-derived surface albedo with calibrated regional climate modeled surface air temperature and surface downward solar irradiance, we determine the spatial dependence and quantitative impact of the ice sheet albedo feedback over 12 summer periods beginning in 2000. We find that, while albedo feedback defined by the change in net solar shortwave flux and temperature over time is positive over 97% of the ice sheet, when defined using paired annual anomalies, a second-order negative feedback is evident over 63% of the accumulation area. This negative feedback damps the accumulation area response to warming due to a positive correlation between snowfall and surface air temperature anomalies. Positive anomaly-gauged feedback concentrated in the ablation area accounts for more than half of the overall increase in melting when satellite-derived melt duration is used to define the timing when net shortwave flux is sunk into melting. Abnormally strong anticyclonic circulation, associated with a persistent summer North Atlantic Oscillation extreme since 2007, enabled three amplifying mechanisms to maximize the albedo feedback: (1 increased warm (south air advection along the western ice sheet increased surface sensible heating that in turn enhanced snow grain metamorphic rates, further reducing albedo; (2 increased surface downward shortwave flux, leading to more surface heating and further albedo reduction; and (3 reduced snowfall rates sustained low albedo, maximizing surface solar heating, progressively lowering albedo over multiple years. The summer net infrared and solar radiation for the high elevation accumulation area approached

  17. Possible role of anti-SSA/Ro antibodies in the pathogenesis of pulmonary hypertension

    Directory of Open Access Journals (Sweden)

    Kelsey Guerreso

    2016-01-01

    Conclusion: It is known that pulmonary hypertension has association with autoimmune diseases, however no clear markers yet exist. Anti-SSA/Ro antibodies have been rarely described in cases of pulmonary disease, and less so in pulmonary hypertension. This case describes a unique association between isolated pulmonary hypertension and anti-SSA/Ro antibody, thereby illustrating the need to investigate this autoantibody and others in the pathogenesis of autoimmune pulmonary hypertension.

  18. Newborn infant with maternal anti-SSA antibody-induced complete heart block accompanying cardiomyopathy.

    Science.gov (United States)

    Iida, Midori; Inamura, Noboru; Takeuchi, Makoto

    2006-01-01

    Newborn case of maternal anti-SSA antibody-induced congenital complete heart block (CCHB) accompanying cardiomyopathy is presented. Unexpectedly, she died of ventricular tachycardia, not bradycardia, 6 days after birth. Autopsy revealed left ventricular cardiomyopathy with endocardial fibroelastosis. Thus, when evaluating fetal cardiac performance in cases of maternal anti-SSA antibody-induced CCHB, it is necessary to pay attention to myocardial attributes such as endocardial hyperplasia.

  19. Albedo's determination by the method of neutron impulse

    International Nuclear Information System (INIS)

    Flores Calderon, J.E.

    1982-01-01

    Experiments with non-stationary neutron transport in large cavity moderators (l>>Σsub(tr) -1 ) (where l is the characteristic cavity length and Σsub(tr) -1 the macroscopic transport section of the moderator) led to the method reported in this study which, based on neutron impulses for determining albedo of thermal neutrons, gave a precision greater by an order of magnitude over previous methods. A sufficient time interval after introduction of the neutron flux into the moderator chamber decreased exponentially the decay constant L, which was itself related to albedo by a function called f. Numerical calculations of albedo were assisted. (author)

  20. GillespieSSA: Implementing the Gillespie Stochastic Simulation Algorithm in R

    Directory of Open Access Journals (Sweden)

    Mario Pineda-Krch

    2008-02-01

    Full Text Available The deterministic dynamics of populations in continuous time are traditionally described using coupled, first-order ordinary differential equations. While this approach is accurate for large systems, it is often inadequate for small systems where key species may be present in small numbers or where key reactions occur at a low rate. The Gillespie stochastic simulation algorithm (SSA is a procedure for generating time-evolution trajectories of finite populations in continuous time and has become the standard algorithm for these types of stochastic models. This article presents a simple-to-use and flexible framework for implementing the SSA using the high-level statistical computing language R and the package GillespieSSA. Using three ecological models as examples (logistic growth, Rosenzweig-MacArthur predator-prey model, and Kermack-McKendrick SIRS metapopulation model, this paper shows how a deterministic model can be formulated as a finite-population stochastic model within the framework of SSA theory and how it can be implemented in R. Simulations of the stochastic models are performed using four different SSA Monte Carlo methods: one exact method (Gillespie's direct method; and three approximate methods (explicit, binomial, and optimized tau-leap methods. Comparison of simulation results confirms that while the time-evolution trajectories obtained from the different SSA methods are indistinguishable, the approximate methods are up to four orders of magnitude faster than the exact methods.

  1. Hydraulic and mechanical behavior of landfill clay liner containing SSA in contact with leachate.

    Science.gov (United States)

    Zhang, Qian; Lu, Haijun; Liu, Junzhu; Wang, Weiwei; Zhang, Xiong

    2018-05-01

    Sewage sludge ash (SSA) produced by municipal sludge can be used as a modified additive for clay liner, and improves the working performance of landfill clay liner in contact with leachate. Under the action of landfill leachate, the permeability, shear strength, phase composition, and pore structure of the modified clay are investigated through the flexible wall permeability test, triaxial shear test, thermal gravimetric and differential thermal analysis, and low-temperature nitrogen adsorption test, respectively. The hydraulic conductivity of the modified clay containing 0-5% SSA is in the range of 3.94 × 10 -8 -1.16 × 10 -7  cm/s, and the pollutant concentration of the sample without SSA was higher than others. The shear strength of the modified clay is more than that of the traditional clay liner, the cohesion rate of modified clay increases from 32.5 to 199.91 kPa, and the internal friction angle decreases from 32.5° to 15.6°. Furthermore, the weight loss rates of the samples are 15.69%, 17.92%, 18.06%, and 20.68%, respectively, when the SSA content increases from 0% to 5%. The total pore volume and average pore diameter of the modified clay decrease with the increase in the SSA content, respectively. However, the specific area of the modified clay increases with the increase in the SSA content.

  2. PROVE Surface albedo of Jornada Experimental Range, New Mexico, 1997

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this study was to determine the spatial variations in field measurements of broadband albedo as related to the ground cover and under a range of...

  3. PROVE Surface albedo of Jornada Experimental Range, New Mexico, 1997

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The objective of this study was to determine the spatial variations in field measurements of broadband albedo as related to the ground cover and under a...

  4. Greenland ice sheet albedo variability and feedback: 2000-2015

    Science.gov (United States)

    Box, J. E.; van As, D.; Fausto, R. S.; Mottram, R.; Langen, P. P.; Steffen, K.

    2015-12-01

    Absorbed solar irradiance represents the dominant source of surface melt energy for Greenland ice. Surface melting has increased as part of a positive feedback amplifier due to surface darkening. The 16 most recent summers of observations from the NASA MODIS sensor indicate a darkening exceeding 6% in July when most melting occurs. Without the darkening, the increase in surface melting would be roughly half as large. A minority of the albedo decline signal may be from sensor degradation. So, in this study, MOD10A1 and MCD43 albedo products from MODIS are evaluated for sensor degradation and anisotropic reflectance errors. Errors are minimized through calibration to GC-Net and PROMICE Greenland snow and ice ground control data. The seasonal and spatial variability in Greenland snow and ice albedo over a 16 year period is presented, including quantifying changing absorbed solar irradiance and melt enhancement due to albedo feedback using the DMI HIRHAM5 5 km model.

  5. Correcting the Response of an Albedo Neutron Dosimeter for Energy

    National Research Council Canada - National Science Library

    Riel, Gordon K; Winters, Patrick J; Cassata, James R; St. John, Ted; Benevides, Luis A

    2007-01-01

    The neutron response of an albedo neutron dosimeter varies greatly with energy. For example, the dosimeter, calibrated with moderated Californium fission neutrons, will read more than 30 times the dose from thermal neutrons and less than 3...

  6. ALBEDO PATTERN RECOGNITION AND TIME-SERIES ANALYSES IN MALAYSIA

    Directory of Open Access Journals (Sweden)

    S. A. Salleh

    2012-07-01

    Full Text Available Pattern recognition and time-series analyses will enable one to evaluate and generate predictions of specific phenomena. The albedo pattern and time-series analyses are very much useful especially in relation to climate condition monitoring. This study is conducted to seek for Malaysia albedo pattern changes. The pattern recognition and changes will be useful for variety of environmental and climate monitoring researches such as carbon budgeting and aerosol mapping. The 10 years (2000–2009 MODIS satellite images were used for the analyses and interpretation. These images were being processed using ERDAS Imagine remote sensing software, ArcGIS 9.3, the 6S code for atmospherical calibration and several MODIS tools (MRT, HDF2GIS, Albedo tools. There are several methods for time-series analyses were explored, this paper demonstrates trends and seasonal time-series analyses using converted HDF format MODIS MCD43A3 albedo land product. The results revealed significance changes of albedo percentages over the past 10 years and the pattern with regards to Malaysia's nebulosity index (NI and aerosol optical depth (AOD. There is noticeable trend can be identified with regards to its maximum and minimum value of the albedo. The rise and fall of the line graph show a similar trend with regards to its daily observation. The different can be identified in term of the value or percentage of rises and falls of albedo. Thus, it can be concludes that the temporal behavior of land surface albedo in Malaysia have a uniform behaviours and effects with regards to the local monsoons. However, although the average albedo shows linear trend with nebulosity index, the pattern changes of albedo with respects to the nebulosity index indicates that there are external factors that implicates the albedo values, as the sky conditions and its diffusion plotted does not have uniform trend over the years, especially when the trend of 5 years interval is examined, 2000 shows high

  7. Automatic Satellite Telemetry Analysis for SSA using Artificial Intelligence Techniques

    Science.gov (United States)

    Stottler, R.; Mao, J.

    In April 2016, General Hyten, commander of Air Force Space Command, announced the Space Enterprise Vision (SEV) (http://www.af.mil/News/Article-Display/Article/719941/hyten-announces-space-enterprise-vision/). The SEV addresses increasing threats to space-related systems. The vision includes an integrated approach across all mission areas (communications, positioning, navigation and timing, missile warning, and weather data) and emphasizes improved access to data across the entire enterprise and the ability to protect space-related assets and capabilities. "The future space enterprise will maintain our nation's ability to deliver critical space effects throughout all phases of conflict," Hyten said. Satellite telemetry is going to become available to a new audience. While that telemetry information should be valuable for achieving Space Situational Awareness (SSA), these new satellite telemetry data consumers will not know how to utilize it. We were tasked with applying AI techniques to build an infrastructure to process satellite telemetry into higher abstraction level symbolic space situational awareness and to initially populate that infrastructure with useful data analysis methods. We are working with two organizations, Montana State University (MSU) and the Air Force Academy, both of whom control satellites and therefore currently analyze satellite telemetry to assess the health and circumstances of their satellites. The design which has resulted from our knowledge elicitation and cognitive task analysis is a hybrid approach which combines symbolic processing techniques of Case-Based Reasoning (CBR) and Behavior Transition Networks (BTNs) with current Machine Learning approaches. BTNs are used to represent the process and associated formulas to check telemetry values against anticipated problems and issues. CBR is used to represent and retrieve BTNs that represent an investigative process that should be applied to the telemetry in certain circumstances

  8. IAU nomenclature for albedo features on the planet Mercury

    Science.gov (United States)

    Dollfus, A.; Chapman, C. R.; Davies, M. E.; Gingerich, O.; Goldstein, R.; Guest, J.; Morrison, D.; Smith, B. A.

    1978-01-01

    The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

  9. Evaluation of coarse scale land surface remote sensing albedo product over rugged terrain

    Science.gov (United States)

    Wen, J.; Xinwen, L.; You, D.; Dou, B.

    2017-12-01

    Satellite derived Land surface albedo is an essential climate variable which controls the earth energy budget and it can be used in applications such as climate change, hydrology, and numerical weather prediction. The accuracy and uncertainty of surface albedo products should be evaluated with a reliable reference truth data prior to applications. And more literatures investigated the validation methods about the albedo validation in a flat or homogenous surface. However, the albedo performance over rugged terrain is still unknow due to the validation method limited. A multi-validation strategy is implemented to give a comprehensive albedo validation, which will involve the high resolution albedo processing, high resolution albedo validation based on in situ albedo, and the method to upscale the high resolution albedo to a coarse scale albedo. Among them, the high resolution albedo generation and the upscale method is the core step for the coarse scale albedo validation. In this paper, the high resolution albedo is generated by Angular Bin algorithm. And a albedo upscale method over rugged terrain is developed to obtain the coarse scale albedo truth. The in situ albedo located 40 sites in mountain area are selected globally to validate the high resolution albedo, and then upscaled to the coarse scale albedo by the upscale method. This paper takes MODIS and GLASS albedo product as a example, and the prelimarily results show the RMSE of MODIS and GLASS albedo product over rugged terrain are 0.047 and 0.057, respectively under the RMSE with 0.036 of high resolution albedo.

  10. Quantifying the ice-albedo feedback through decoupling

    Science.gov (United States)

    Kravitz, B.; Rasch, P. J.

    2017-12-01

    The ice-albedo feedback involves numerous individual components, whereby warming induces sea ice melt, inducing reduced surface albedo, inducing increased surface shortwave absorption, causing further warming. Here we attempt to quantify the sea ice albedo feedback using an analogue of the "partial radiative perturbation" method, but where the governing mechanisms are directly decoupled in a climate model. As an example, we can isolate the insulating effects of sea ice on surface energy and moisture fluxes by allowing sea ice thickness to change but fixing Arctic surface albedo, or vice versa. Here we present results from such idealized simulations using the Community Earth System Model in which individual components are successively fixed, effectively decoupling the ice-albedo feedback loop. We isolate the different components of this feedback, including temperature change, sea ice extent/thickness, and air-sea exchange of heat and moisture. We explore the interactions between these different components, as well as the strengths of the total feedback in the decoupled feedback loop, to quantify contributions from individual pieces. We also quantify the non-additivity of the effects of the components as a means of investigating the dominant sources of nonlinearity in the ice-albedo feedback.

  11. Albedo as a modulator of climate response to tropical deforestation

    Science.gov (United States)

    Dirmeyer, Paul A.; Shukla, J.

    1994-01-01

    An atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years' duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.

  12. Retrieval of snow albedo and grain size using reflectance measurements in Himalayan basin

    OpenAIRE

    H. S. Negi; A. Kokhanovsky

    2010-01-01

    In the present paper spectral reflectance measurements of Himalayan seasonal snow were carried out and analysed to retrieve the snow albedo and effective grain size. The asymptotic radiative transfer (ART) theory was applied to retrieve the plane and spherical albedo. The retrieved plane albedo was compared with the measured spectral albedo and a good agreement was observed with ±10% measured error accuracy. Retrieved integrated albedo was found within ±6% difference with ground observed broa...

  13. High-albedo materials for reducing building cooling energy use

    Energy Technology Data Exchange (ETDEWEB)

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building`s envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  14. High-albedo materials for reducing building cooling energy use

    Energy Technology Data Exchange (ETDEWEB)

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building's envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  15. Anti-Ro/SSA antibodies and cardiac arrhythmias in the adult: facts and hypotheses.

    Science.gov (United States)

    Lazzerini, P E; Capecchi, P L; Laghi-Pasini, F

    2010-09-01

    It is well established that the passive trans-placental passage of anti-Ro/SSA antibodies from mother to foetus is associated with the risk to develop an uncommon syndrome named neonatal lupus (NLE), where the congenital heart block represents the most severe clinical feature. Recent evidence demonstrated that also adult heart, classically considered invulnerable to the anti-Ro/SSA antibodies, may represent a target of the arrhythmogenicity of these autoantibodies. In particular, the prolongation of the QTc interval appears the most frequent abnormality observed in adults with circulating anti-Ro/SSA antibodies, with some data suggesting an association with an increased risk of ventricular arrhythmias, also life threatening. Moreover, even though the association between anti-Ro/SSA antibodies and conduction disturbances is undoubtedly less evident in adults than in infants, from the accurate dissection of the literature data the possibility arises that sometimes also the adult cardiac conduction tissue may be affected by such antibodies. The exact arrhythmogenic mechanisms involved in foetus/newborns and adults, respectively, have not been completely clarified as yet. However, increasing evidence suggests that anti-Ro/SSA antibodies may trigger rhythm disturbances through an inhibiting cross-reaction with several cardiac ionic channels, particularly the calcium channels (L-type and T-type), but also the potassium channel hERG, whose different expression and involvement in the cardiac electrophysiology during lifespan might account for the occurrence of age-related differences.

  16. Global Cooling: Effect of Urban Albedo on Global Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur

    2007-05-22

    In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). The roof and the pavement albedo can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60%. We estimate U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills. Increasing albedo of urban surfaces can reduce the summertime urban temperature and improve the urban air quality. Increasing the urban albedo has the added benefit of reflecting more of the incoming global solar radiation and countering the effect of global warming. We estimate that increasing albedo of urban areas by 0.1 results in an increase of 3 x 10{sup -4} in Earth albedo. Using a simple global model, the change in air temperature in lowest 1.8 km of the atmosphere is estimated at 0.01K. Modelers predict a warming of about 3K in the next 60 years (0.05K/year). Change of 0.1 in urban albedo will result in 0.01K global cooling, a delay of {approx}0.2 years in global warming. This 0.2 years delay in global warming is equivalent to 10 Gt reduction in CO2 emissions.

  17. A Continental United States High Resolution NLCD Land Cover – MODIS Albedo Database to Examine Albedo and Land Cover Change Relationships

    Science.gov (United States)

    Surface albedo influences climate by affecting the amount of solar radiation that is reflected at the Earth’s surface, and surface albedo is, in turn, affected by land cover. General Circulation Models typically use modeled or prescribed albedo to assess the influence of land co...

  18. Synthesis and crystal structures of a novel layered silicate SSA-1 and its microporous derivatives by topotactic transformation.

    Science.gov (United States)

    Takahashi, S; Kurita, Y; Ikeda, T; Miyamoto, M; Uemiya, S; Oumi, Y

    2016-10-18

    The synthesis of a novel layered silicate SSA-1 (SSA: silicate synthesized with a quaternary amine) was achieved in the SiO 2 -H 2 O-TEAOH (TEAOH: tetraethylammonium hydroxide - as an organic structural directing agent) system. The crystal structure of SSA-1 involved two silicate layers composed of bre [10T]-type CBU (Composite Building Unit) and TEAOH in interlayers. The topotactic transformation of SSA-1 by calcination was examined, resulting in a porous material (PML-1: porous material transformed from a layered silicate) with a 108 m 2 g -1 BET surface area and 0.035 cm 3 g -1 pore volume. PML-1 is a siliceous microporous material with silanols in the framework and possesses unique properties, such as hydrophilicity, in spite of all its silica composition. The most reasonable crystal structure of PML-1 was successfully determined on the basis of the crystal structure of SSA-1 by a combination of manual modelling, PXRD pattern simulation, DFT optimization and Rietveld analysis. Additionally, an interlayer expanded siliceous zeolite SSA-1 (IEZ-SSA-1) was also successfully prepared by silylation using trichloro(methyl)silane under acidic conditions. IEZ-SSA-1 showed hydrophilicity or hydrophobicity properties by changing the functional group of the pillar part in the interlayer. Additionally, IEZ-SSA-1 showed a large gas adsorption property (537 m 2 g -1 and 0.21 cm 3 g -1 ).

  19. Relating black carbon content to reduction of snow albedo

    Science.gov (United States)

    Brandt, R. E.; Warren, S. G.; Clarke, A. D.

    2011-12-01

    In remote snow of the Northern Hemisphere, the levels of soot pollution are in the parts-per-billion (ppb) range, where the effect on albedo is at the level of a few percent. A reduction of albedo by 1-2% is significant for climate but is difficult to detect experimentally, because snow albedo depends on several other variables. In our work to quantify the climatic effect of black carbon (BC) in snow, we therefore do not directly measure the albedo reduction. Instead, we use a two-step procedure: (1) We collect snow samples, melt and filter them, and analyze the filters spectrophotometrically for BC concentration. (2) We use the BC amount from the filter measurement, together with snow grain size, in a radiative transfer model to compute the albedo reduction. Our radiative transfer model uses the discrete ordinates algorithm DISORT 2.0. We have chosen a representative BC size distribution and optical constants, and have incorporated those of mineral dust as well. While a given mass of BC causes over an order of magnitude more snow albedo reduction compared to dust, a snowpack containing dust mutes the albedo-reducing effect of BC. Because the computed reduction of snow albedo is model-based, it requires experimental verification. We doubt that direct measurement of albedo-reduction will be feasible in nature, because of the vertical variation of both snow grain size and soot content, and because the natural soot content is small. We conclude that what is needed is an artificial snowpack, with uniform grain size and large uniform soot content (ppm not ppb), to produce a large signal on albedo. We have chosen to pursue this experiment outdoors rather than in the laboratory, for the following reasons: (1) The snowpack in the field of view is uniformly illuminated if the source of radiation is the Sun. (2) Visible radiation penetrates into the snow, so photons emerge horizontally distant from where they entered. In the limited width of a laboratory snowpack, radiation

  20. Higher albedos and size distribution of large transneptunian objects

    Science.gov (United States)

    Lykawka, Patryk Sofia; Mukai, Tadashi

    2005-11-01

    Transneptunian objects (TNOs) orbit beyond Neptune and do offer important clues about the formation of our solar system. Although observations have been increasing the number of discovered TNOs and improving their orbital elements, very little is known about elementary physical properties such as sizes, albedos and compositions. Due to TNOs large distances (>40 AU) and observational limitations, reliable physical information can be obtained only from brighter objects (supposedly larger bodies). According to size and albedo measurements available, it is evident the traditionally assumed albedo p=0.04 cannot hold for all TNOs, especially those with approximately absolute magnitudes H⩽5.5. That is, the largest TNOs possess higher albedos (generally >0.04) that strongly appear to increase as a function of size. Using a compilation of published data, we derived empirical relations which can provide estimations of diameters and albedos as a function of absolute magnitude. Calculations result in more accurate size/albedo estimations for TNOs with H⩽5.5 than just assuming p=0.04. Nevertheless, considering low statistics, the value p=0.04 sounds still convenient for H>5.5 non-binary TNOs as a group. We also discuss about physical processes (e.g., collisions, intrinsic activity and the presence of tenuous atmospheres) responsible for the increase of albedo among large bodies. Currently, all big TNOs (>700 km) would be capable to sustain thin atmospheres or icy frosts composed of CH 4, CO or N 2 even for body bulk densities as low as 0.5 g cm -3. A size-dependent albedo has important consequences for the TNOs size distribution, cumulative luminosity function and total mass estimations. According to our analysis, the latter can be reduced up to 50% if higher albedos are common among large bodies. Lastly, by analyzing orbital properties of classical TNOs ( 42AUbodies. For both populations, distinct absolute magnitude distributions are maximized for an inclination threshold

  1. MELiSSA celebrates 25 years of research into life support

    International Nuclear Information System (INIS)

    2015-01-01

    MELiSSA (Micro-Ecological Life Support System Alternative) is a collaborative project with the European Space Agency ESA and various other scientific partners. The objective of MELiSSA is to develop a system that is able to provide manned space missions with food, drinking water and oxygen autonomously in space. Drinkable water and oxygen are currently being made in the international space station ISS by filtering waste water and by electrolysing water. However, such physiochemical technologies do not offer a solution for food. The MELiSSA project intends to reuse waste products, which include CO2, water, stools and urine from the astronauts, and even the perspiration moisture in the cabin and to transfer these into food through the use of micro-organisms.

  2. Size and Albedo of Irregular Saturnian Satellites from Spitzer Observations

    Science.gov (United States)

    Mueller, Michael; Grav, T.; Trilling, D.; Stansberry, J.; Sykes, M.

    2008-09-01

    Using MIPS onboard the Spitzer Space Telescope, we observed the thermal emission (24 and, for some targets, 70 um) of eight irregular satellites of Saturn: Albiorix, Siarnaq, Paaliaq, Kiviuq, Ijiraq, Tarvos, Erriapus, and Ymir. We determined the size and albedo of all targets. An analysis of archived MIPS observations of Phoebe reproduces Cassini results very accurately, thereby validating our method. For all targets, the geometric albedo is found to be low, probably below 10% and clearly below 15%. Irregular satellites are much darker than the large regular satellites. Their albedo is, however, quite similar to that of small bodies in the outer Solar System (such as cometary nuclei, Jupiter Trojans, or TNOs). This is consistent with color measurements as well as dynamical considerations which suggest a common origin of the said populations. There appear to be significant object-to-object albedo differences. Similar albedos found for some members of dynamical clusters support the idea that they may have originated in the breakup of a parent body. For three satellites, thermal data at two wavelengths are available, enabling us to constrain their thermal properties. Sub-solar temperatures are similar to that found from Cassini's Phoebe fly-by. This suggests a rather low thermal inertia, as expected for regolith-covered objects. This work is based on observations made with the Spitzer Space Telescope, which is operated by JPL under a contract with NASA. Support for this work was provided by NASA.

  3. Matrix albedo for discrete ordinates infinite-medium boundary condition

    International Nuclear Information System (INIS)

    Mathews, K.; Dishaw, J.

    2007-01-01

    Discrete ordinates problems with an infinite exterior medium (reflector) can be more efficiently computed by eliminating grid cells in the exterior medium and applying a matrix albedo boundary condition. The albedo matrix is a discretized bidirectional reflection distribution function (BRDF) that accounts for the angular quadrature set, spatial quadrature method, and spatial grid that would have been used to model a portion of the exterior medium. The method is exact in slab geometry, and could be used as an approximation in multiple dimensions or curvilinear coordinates. We present an adequate method for computing albedo matrices and demonstrate their use in verifying a discrete ordinates code in slab geometry by comparison with Ganapol's infinite medium semi-analytic TIEL benchmark. With sufficient resolution in the spatial and angular grids and iteration tolerance to yield solutions converged to 6 digits, the conventional (scalar) albedo boundary condition yielded 2-digit accuracy at the boundary, but the matrix albedo solution reproduced the benchmark scalar flux at the boundary to all 6 digits. (authors)

  4. Occurrence of lower cloud albedo in ship tracks

    Directory of Open Access Journals (Sweden)

    Y.-C. Chen

    2012-09-01

    Full Text Available The concept of geoengineering by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which aerosol-perturbed marine clouds will respond with increased albedo. Ship tracks, quasi-linear cloud features prevalent in oceanic regions impacted by ship exhaust, are a well-known manifestation of the effect of aerosol injection on marine clouds. We present here an analysis of the albedo responses in ship tracks, based on in situ aircraft measurements and three years of satellite observations of 589 individual ship tracks. It is found that the sign (increase or decrease and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height. In a closed cell structure (cloud cells ringed by a perimeter of clear air, nearly 30% of ship tracks exhibited a decreased albedo. Detailed cloud responses must be accounted for in global studies of the potential efficacy of sea-spray geoengineering as a means to counteract global warming.

  5. Tundra vegetation effects on pan-Arctic albedo

    International Nuclear Information System (INIS)

    Loranty, Michael M; Goetz, Scott J; Beck, Pieter S A

    2011-01-01

    Recent field experiments in tundra ecosystems describe how increased shrub cover reduces winter albedo, and how subsequent changes in surface net radiation lead to altered rates of snowmelt. These findings imply that tundra vegetation change will alter regional energy budgets, but to date the effects have not been documented at regional or greater scales. Using satellite observations and a pan-Arctic vegetation map, we examined the effects of shrub vegetation on albedo across the terrestrial Arctic. We included vegetation classes dominated by low shrubs, dwarf shrubs, tussock-dominated graminoid tundra, and non-tussock graminoid tundra. Each class was further stratified by bioclimate subzones. Low-shrub tundra had higher normalized difference vegetation index values and earlier albedo decline in spring than dwarf-shrub tundra, but for tussock tundra, spring albedo declined earlier than for low-shrub tundra. Our results illustrate how relatively small changes in vegetation properties result in differences in albedo dynamics, regardless of shrub growth, that may lead to differences in net radiation upwards of 50 W m -2 at weekly time scales. Further, our findings imply that changes to the terrestrial Arctic energy budget during this important seasonal transition are under way regardless of whether recent satellite observed productivity trends are the result of shrub expansion. We conclude that a better understanding of changes in vegetation productivity and distribution in Arctic tundra is essential for accurately quantifying and predicting carbon and energy fluxes and associated climate feedbacks.

  6. Land surface albedo bias in climate models and its association with tropical rainfall

    Science.gov (United States)

    Levine, Xavier J.; Boos, William R.

    2017-06-01

    The influence of surface albedo on tropical precipitation is widely appreciated, but albedo bias over snow-free areas in climate models has been studied little. Here historical Coupled Model Intercomparison Project Phase 5 simulations are shown to exhibit large multimodel mean bias and intermodel variability in boreal summer mean surface broadband shortwave albedo. Intermodel variability in this albedo is globally coherent over vegetated regions and correlates with intermodel tropical precipitation variability. Evidence supports the hypothesis that these spatially coherent albedo variations cause precipitation variations. Specifically, spatial structures of albedo and precipitation variations are distinct, suggesting the latter do not cause the former by darkening soil. Furthermore, simulated interannual albedo variance is small compared to intermodel albedo variance, while the ratio of interannual to intermodel precipitation variance is much larger. Finally, imposing the dominant pattern of intermodel albedo variability in one climate model causes a precipitation change with structure similar to that of the intermodel variability.

  7. MORSE/STORM: A generalized albedo option for Monte Carlo calculations

    International Nuclear Information System (INIS)

    Gomes, I.C.; Stevens, P.N.

    1991-09-01

    The advisability of using the albedo procedure for the Monte Carlo solution of deep penetration shielding problems that have ducts and other penetrations has been investigated. The use of albedo data can dramatically improve the computational efficiency of certain Monte Carlo calculations. However, the accuracy of these results may be unacceptable because of lost information during the albedo event and serious errors in the available differential albedo data. This study was done to evaluate and appropriately modify the MORSE/BREESE package, to develop new methods for generating the required albedo data, and to extend the adjoint capability to the albedo-modified calculations. Major modifications to MORSE/BREESE include an option to save for further use information that would be lost at the albedo event, an option to displace the point of emergence during an albedo event, and an option to use spatially dependent albedo data for both forward and adjoint calculations, which includes the point of emergence as a new random variable to be selected during an albedo event. The theoretical basis for using TORT-generated forward albedo information to produce adjuncton albedos was derived. The MORSE/STORM package was developed to perform both forward and adjoint modes of analysis using spatially dependent albedo data. Results obtained with MORSE/STORM for both forward and adjoint modes were compared with benchmark solutions. Excellent agreement and improved computational efficiency were achieved, demonstrating the full utilization of the albedo option in the MORSE code. 7 refs., 17 figs., 15 tabs

  8. BOREAS TE-1 Soils Data Over The SSA Tower Sites in Raster Format

    Science.gov (United States)

    Hall, Forrest G. (Editor); Anderson, Darwin; Knapp, David E.

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. This data set was gridded from vector layers of soil maps that were received from Dr. Darwin Anderson (TE-1), who did the original soil mapping in the field during 1994. The vector layers were gridded into raster files that cover approximately 1 square kilometer over each of the tower sites in the SSA. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  9. Brazilian two-component TLD albedo neutron individual monitoring system

    Energy Technology Data Exchange (ETDEWEB)

    Martins, M.M., E-mail: marcelo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Mauricio, C.L.P., E-mail: claudia@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Fonseca, E.S. da, E-mail: evaldo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Silva, A.X. da, E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao em Engenharia, COPPE/PEN Caixa Postal 68509, CEP: 21941-972, Rio de Janeiro, RJ (Brazil)

    2010-12-15

    Since 1983, Instituto de Radioprotecao e Dosimetria, Brazil, uses a TLD one-component albedo neutron monitor, which has a single different calibration factor specifically for each installation type. In order to improve its energy response, a two-component albedo monitor was developed, which measure the thermal neutron component besides the albedo one. The two-component monitor has been calibrated in reference neutron fields: thermal, five accelerator-produced monoenergetic beams (70, 144, 565, 1200 and 5000 keV) and five radionuclide sources ({sup 252}Cf, {sup 252}Cf(D{sub 2}O), {sup 241}Am-Be, {sup 241}Am-B and {sup 238}Pu-Be) at several distances. Since January 2008, mainly Brazilian workers who handle neutron sources at different distances and moderation, such as in well logging and calibration facilities are using it routinely.

  10. Diurnal variations in the UV albedo of arctic snow

    Directory of Open Access Journals (Sweden)

    O. Meinander

    2008-11-01

    Full Text Available The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l. during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

  11. Detailed spatiotemporal albedo observations at Greenland's Mittivakkat Gletscher

    Science.gov (United States)

    Mernild, Sebastian H.; Knudsen, Niels T.; Yde, Jacob C.; Malmros, Jeppe K.

    2015-04-01

    Surface albedo is defined as the reflected fraction of incoming solar shortwave radiation at the surface. On Greenland's Mittivakkat Gletscher the mean glacier-wide MODIS-estimated albedo dropped by 0.10 (2000-2013) from 0.43 to 0.33 by the end of the mass balance year (EBY). Hand-held albedo measurements as low as 0.10 were observed over debris-covered ice at the glacier margin at the EBY: these values were slightly below observed values for proglacial bedrock (~0.2). The albedo is highly variable in space - a significant variability occurred within few meters at the glacier margin area ranging from 0.10 to 0.39 due to variability in debris-cover thickness and composition, microbial activity (including algae and cyanobacteria), snow grain crystal metamorphism, bare ice exposure, and meltwater ponding. Huge dark-red-brown-colored ice algae colonies were observed. Albedo measurements on snow patches and bare glacier ice changed significant with increasing elevations (180-600 m a.s.l.) by lapse rates of 0.04 and 0.03 per 100 m, respectively, indicating values as high as 0.82 and 0.40 on the upper part of the glacier. Over a period of two weeks from early August to late August 2014 the hand-held observed mean glacier-wide albedo changed from 0.40 to 0.30 indicating that on average 10% more incoming solar shortwave radiation became available for surface ablation at the end of the melt season.

  12. NEOWISE REACTIVATION MISSION YEAR ONE: PRELIMINARY ASTEROID DIAMETERS AND ALBEDOS

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R.; Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S.; Stevenson, R. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States); Wright, E. L., E-mail: cnugent@ipac.caltech.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2015-12-01

    We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or “NEOWISE” thermal measurements. Diameters are determined to an accuracy of ∼20% or better. If good-quality H magnitudes are available, albedos can be determined to within ∼40% or better.

  13. Comparative global albedo and color maps of the Uranian satellites

    International Nuclear Information System (INIS)

    Buratti, B.J.; Mosher, J.A.

    1991-01-01

    The surfaces of the Uranian satellites Ariel, Miranda, Oberon, Titania, and Umbriel are characterized on the basis of Voyager observations. Tables of spectrophotometric data and maps of normal reflectances, green/violet ratios, and possible geological formations are presented and discussed in detail. Variations in albedo are found to be associated with impact features, and it is inferred from color differences that the upper surface of Ariel contains a higher proportion of redder material (tentatively identified as accreted low-albedo meteoritic dust) than those of the other moons. 42 refs

  14. Validation of response simulation methodology of Albedo dosemeter

    International Nuclear Information System (INIS)

    Freitas, B.M.; Silva, A.X. da

    2016-01-01

    The Instituto de Radioprotecao e Dosimetria developed and runs a neutron TLD albedo individual monitoring service. To optimize the dose calculation algorithm and to infer new calibration factors, the response of this dosemeter was simulated. In order to validate this employed methodology, it was applied in the simulation of the problem of the QUADOS (Quality Assurance of Computational Tools for Dosimetry) intercomparison, aimed to evaluate dosimetric problems, one being to calculate the response of a generic albedo dosemeter. The obtained results were compared with those of other modeling and the reference one, with good agreements. (author)

  15. Ceres Photometry and Albedo from Dawn Framing Camera Images

    Science.gov (United States)

    Schröder, S. E.; Mottola, S.; Keller, H. U.; Li, J.-Y.; Matz, K.-D.; Otto, K.; Roatsch, T.; Stephan, K.; Raymond, C. A.; Russell, C. T.

    2015-10-01

    The Dawn spacecraft is in orbit around dwarf planet Ceres. The onboard Framing Camera (FC) [1] is mapping the surface through a clear filter and 7 narrow-band filters at various observational geometries. Generally, Ceres' appearance in these images is affected by shadows and shading, effects which become stronger for larger solar phase angles, obscuring the intrinsic reflective properties of the surface. By means of photometric modeling we attempt to remove these effects and reconstruct the surface albedo over the full visible wavelength range. Knowledge of the albedo distribution will contribute to our understanding of the physical nature and composition of the surface.

  16. The high albedo of the hot Jupiter Kepler-7b

    DEFF Research Database (Denmark)

    Demory, B.-O.; Seager, S.; Madhusudhan, N.

    2011-01-01

    Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations....... The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass...

  17. 75 FR 7648 - Privacy Act of 1974, as Amended; Computer Matching Program (SSA/Department of Veterans Affairs...

    Science.gov (United States)

    2010-02-22

    .../Veterans Benefits Administration (VA/ VBA))--Match Number 1309 AGENCY: Social Security Administration (SSA... announces a renewal of an existing computer matching program that we are currently conducting with VA/VBA... Matching Program, SSA With the Department of Veterans Affairs/Veterans Benefits Administration (VA/VBA) A...

  18. 20 CFR 408.1235 - How does the State transfer funds to SSA to administer its recognition payment program?

    Science.gov (United States)

    2010-04-01

    ... administer its recognition payment program? 408.1235 Section 408.1235 Employees' Benefits SOCIAL SECURITY... fifth business day following such date. (b) Accounting of State funds. (1) As soon as feasible after the... balance of the State's cash on deposit with SSA. (2) SSA will provide the State with an accounting of...

  19. 20 CFR 411.597 - Will SSA periodically review the outcome payment system and the outcome-milestone payment system...

    Science.gov (United States)

    2010-04-01

    ... Employment Network Payment Systems § 411.597 Will SSA periodically review the outcome payment system and the outcome-milestone payment system for possible modifications? (a) Yes. We will periodically review the... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Will SSA periodically review the outcome...

  20. 76 FR 55690 - Submission for OMB Review; Comment Request; The SSA-NIH Collaboration To Improve the Disability...

    Science.gov (United States)

    2011-09-08

    ...; Comment Request; The SSA-NIH Collaboration To Improve the Disability Determination Process: Validation of... Collection: Title: The SSA-NIH Collaboration to Improve the Disability Determination Process: Validation of IRT-CAT tools. Type of Information Collection Request: NEW. Need and Use of Information Collection...

  1. Lupus systémique et atteinte rénale: Apport des anticorps anti-SSA ...

    African Journals Online (AJOL)

    -SSA dans 12 cas (40%).Cinq patients (62.5%) ayant une atteinte rénale avaient des anticorps anti DNA négatifs. Parmi ces patients avec atteinte rénale, 37.5% avaient des anticorps anti SSA sans anticorps anti DNA. La moitié des patients ...

  2. Assessment of the Suomi NPP VIIRS Land Surface Albedo Data Using Station Measurements and High-Resolution Albedo Maps

    Directory of Open Access Journals (Sweden)

    Yuan Zhou

    2016-02-01

    Full Text Available Land surface albedo (LSA, one of the Visible Infrared Imaging Radiometer Suite (VIIRS environmental data records (EDRs, is a fundamental component for linking the land surface and the climate system by regulating shortwave energy exchange between the land and the atmosphere. Currently, the improved bright pixel sub-algorithm (BPSA is a unique algorithm employed by VIIRS to routinely generate LSA EDR from VIIRS top-of-atmosphere (TOA observations. As a product validation procedure, LSA EDR reached validated (V1 stage maturity in December 2014. This study summarizes recent progress in algorithm refinement, and presents comprehensive validation and evaluation results of VIIRS LSA by using extensive field measurements, Moderate Resolution Imaging Spectroradiometer (MODIS albedo product, and Landsat-retrieved albedo maps. Results indicate that: (1 by testing the updated desert-specific look-up-table (LUT that uses a stricter standard to select the training data specific for desert aerosol type in our local environment, it is found that the VIIRS LSA retrieval accuracy is improved over a desert surface and the absolute root mean square error (RMSE is reduced from 0.036 to 0.023, suggesting the potential of the updated desert LUT to the improve the VIIRS LSA product accuracy; (2 LSA retrieval on snow-covered surfaces is more accurate if the newly developed snow-specific LUT (RMSE = 0.082 replaces the generic LUT (RMSE = 0.093 that is employed in the current operational LSA EDR production; (3 VIIRS LSA is also comparable to high-resolution Landsat albedo retrieval (RMSE < 0.04, although Landsat albedo has a slightly higher accuracy, probably owing to higher spatial resolution with less impacts of mixed pixel; (4 VIIRS LSA retrievals agree well with the MODIS albedo product over various land surface types, with overall RMSE of lower than 0.05 and the overall bias as low as 0.025, demonstrating the comparable data quality between VIIRS and the MODIS LSA

  3. An application of the Krylov-FSP-SSA method to parameter fitting with maximum likelihood

    Science.gov (United States)

    Dinh, Khanh N.; Sidje, Roger B.

    2017-12-01

    Monte Carlo methods such as the stochastic simulation algorithm (SSA) have traditionally been employed in gene regulation problems. However, there has been increasing interest to directly obtain the probability distribution of the molecules involved by solving the chemical master equation (CME). This requires addressing the curse of dimensionality that is inherent in most gene regulation problems. The finite state projection (FSP) seeks to address the challenge and there have been variants that further reduce the size of the projection or that accelerate the resulting matrix exponential. The Krylov-FSP-SSA variant has proved numerically efficient by combining, on one hand, the SSA to adaptively drive the FSP, and on the other hand, adaptive Krylov techniques to evaluate the matrix exponential. Here we apply this Krylov-FSP-SSA to a mutual inhibitory gene network synthetically engineered in Saccharomyces cerevisiae, in which bimodality arises. We show numerically that the approach can efficiently approximate the transient probability distribution, and this has important implications for parameter fitting, where the CME has to be solved for many different parameter sets. The fitting scheme amounts to an optimization problem of finding the parameter set so that the transient probability distributions fit the observations with maximum likelihood. We compare five optimization schemes for this difficult problem, thereby providing further insights into this approach of parameter estimation that is often applied to models in systems biology where there is a need to calibrate free parameters. Work supported by NSF grant DMS-1320849.

  4. Ro/SSA autoantibody-positive pregnancy: reactions to serial fetal Doppler echocardiographic surveillance.

    Science.gov (United States)

    Tingström, J; Hjelmstedt, A; Welin Henriksson, E; Sonesson, S-E; Wahren-Herlenius, M

    2015-12-01

    The risk for congenital heart block (CHB) associated with maternal Ro/SSA autoantibodies is low, but the possibility of treating early stages of disease has seen the introduction of Doppler echocardiographic surveillance programs with serial examinations during the CHB susceptibility weeks of pregnancy. The aim of the present study was to understand how Ro/SSA autoantibody-positive women having undergone Doppler echocardiographic surveillance programs and giving birth to children without CHB experienced their pregnancy and frequent ultrasound examinations. A validated questionnaire based on data from an interview-study was distributed to Ro/SSA-positive women supervised with Doppler examinations during their pregnancy (n = 100). The response rate was 79%. The majority of the women (61%) reported that the increased number of ultrasound examinations influenced their pregnancy, but in a positive way, with qualified information and additional support from health care personnel in conjunction with the examinations. Further, the visits to the clinic provided opportunities to see the ultrasound picture of the expected infant. However, one-third of the women also reported stress in relation to the examinations. Fetal echocardiographic surveillance holds many and predominantly positive effects for Ro/SSA-positive women during pregnancy in addition to the medical advantages. © The Author(s) 2015.

  5. Possible role of anti-SSA/Ro antibodies in the pathogenesis of pulmonary hypertension.

    Science.gov (United States)

    Guerreso, Kelsey; Conner, Edward Alexander

    2016-01-01

    There are many different causes of pulmonary hypertension and the pathogenesis of the disease is still being elucidated. Although they are not the most common, autoimmunity and inflammation have been identified as possible causes. No one autoantibody has been identified as the definite cause of pulmonary hypertension. We present a rare association of anti-SSA/Ro antibodies and isolated pulmonary hypertension. A 53 year old African American female presented with abdominal pain, nausea, weight loss, dyspnea and fatigue. Upon further exam she was found to have high titers of antinuclear antibodies and anti-SSA/Ro antibodies. This antibody profile would typically be suggestive of Sjögren's Syndrome, which is characterized by dry eyes and poor salivary gland function. However, since this patient did not have any symptoms consistent with the disease a diagnosis of Sjögren's Syndrome could not be made. A combination of laboratory, imaging and diagnostic studies were done that revealed a final diagnosis of pulmonary hypertension. It is known that pulmonary hypertension has association with autoimmune diseases, however no clear markers yet exist. Anti-SSA/Ro antibodies have been rarely described in cases of pulmonary disease, and less so in pulmonary hypertension. This case describes a unique association between isolated pulmonary hypertension and anti-SSA/Ro antibody, thereby illustrating the need to investigate this autoantibody and others in the pathogenesis of autoimmune pulmonary hypertension.

  6. ESA SSA Space Radiation Expert Service Centre: the Importance of Community Feedback

    Science.gov (United States)

    Crosby, Norma; Dierckxsens, Mark; Kruglanski, Michel; De Donder, Erwin; Calders, Stijn; Messios, Neophytos; Glover, Alexi

    2017-04-01

    End-users in a wide range of sectors both in space and on the ground are affected by space weather. In the frame of its Space Situational Awareness (SSA) programme (http://swe.ssa.esa.int/) the European Space Agency (ESA) is establishing a Space Weather (SWE) Service Network to support end-users in three ways: mitigate the effects of space weather on their systems, reduce costs, and improve reliability. Almost 40 expert groups from institutes and organisations across Europe contribute to this Network organised in five Expert Service Centres (ESCs) - Solar Weather, Heliospheric Weather, Space Radiation, Ionospheric Weather, Geomagnetic Conditions. To understand the end-user needs, the ESCs are supported by the SSCC (SSA Space Weather Coordination Centre) that offers first line support to the end-users. Here we present the mission of the Space Radiation ESC (R-ESC) (http://swe.ssa.esa.int/space-radiation) and the space domain services it supports. Furthermore, we describe how the R-ESC project complements past and ongoing projects both on national level as well as international (e.g. EU projects), emphasizing the importance of inter-disciplinary communication between different communities ranging from scientists, engineers to end-users. Such collaboration is needed if basic science is to be used most efficiently for the development of products and tools that provide end-users with what they actually need. Additionally, feedback from the various communities (projects) is also essential when defining future projects.

  7. BOREAS TF-1 SSA-OA Understory Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Black, T. Andrew; Chen, Z.; Nesic, Zoran

    2000-01-01

    The BOREAS TF-1 team collected energy, carbon dioxide, and momentum flux data under the canopy along with meteorological and soils data at the BOREAS SSA-OA site from mid-October to mid-November of 1993 and throughout all of 1994. The data are available in tabular ASCII files.

  8. BOREAS TF-9 SSA-OBS Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Massheder, Jonathan M.; Moncrieff, John B.; Rayment, Mark B.; Jarvis, Paul G.

    2000-01-01

    The BOREAS TF-9 team collected energy, carbon dioxide, and water vapor flux data at the BOREAS SSA-OBS site during the growing season of 1994 and most of the year for 1996. From the winter of 1995 to 1996, soil temperature data were also collected and provided. The data are available in tabular ASCII files.

  9. BOREAS TF-1 SSA-OA Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Black, T. Andrew; Chen, Z.; Nesic, Zoran

    2000-01-01

    The BOREAS TF-1 team collected energy, carbon dioxide, and momentum flux data above the canopy along with meteorological and soils data at the BOREAS SSA-OA site from mid-April to the end of the year for 1996. The data are available in tabular ASCII files.

  10. Validation of response simulation methodology of Albedo dosemeter; Validacao da metodologia de simulacao de resposta de dosimetro de Albedo

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, B.M.; Silva, A.X. da, E-mail: bfreitas@nuclear.ufrj.br [Coordenacao do Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Mauricio, C.L.P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2016-07-01

    The Instituto de Radioprotecao e Dosimetria developed and runs a neutron TLD albedo individual monitoring service. To optimize the dose calculation algorithm and to infer new calibration factors, the response of this dosemeter was simulated. In order to validate this employed methodology, it was applied in the simulation of the problem of the QUADOS (Quality Assurance of Computational Tools for Dosimetry) intercomparison, aimed to evaluate dosimetric problems, one being to calculate the response of a generic albedo dosemeter. The obtained results were compared with those of other modeling and the reference one, with good agreements. (author)

  11. Anti-TNFa treatment in patients with rheumatoid arthritis and anti-Ro/SSA antibodies

    Directory of Open Access Journals (Sweden)

    P. Airò

    2011-09-01

    Full Text Available Objective: To analyse clinical efficacy, onset of new autoantibodies or symptoms of autoimmune disease in patients affected by rheumatoid arthritis with anti-Ro/SSA treated with anti-TNFa agents. Methods: Six anti-Ro/SSA positive subjects with RA were studied every six months until 24th month of treatment in order to detect ANA titer (IFI, anti-dsDNA (Farr, anti-cardiolipin and anti-beta2glycoprotein I (ELISA, anti-ENA (CIE. The titre of anti-Ro/SSA were analysed by ELISA. Four patients were diagnosed as overlap RA/SS. Results: Six female patients (mean age 58ys, SD 9.8ys, with long-standing RA (mean 7ys, range 5-22 ys were treated with anti-TNFa agents for a mean of 31 months (SD: 20.4 m: 4 with Infliximab and 2 with Etanercept. All the patients showed a significant reduction of DAS until 24th month (p<0.006 with stability of sicca symptoms. The titer of ANA and anti-Ro/SSA was stable, while 4 subjects developed anti-dsDNA at low titer within 6-12 months. One patient withdrawn the treatment, because of lupus-like features; another one, with HCV hepatitis, interrupted Etanercept because of elevation of liver enzymes. No anticardiolipin or antibeta2GPI antibodies were detected. One subject with RA-SS also presented a primary biliary cirrhosis: clinical and histological features of cholangitis remained stable during Etanercept treatment. Conclusions: Anti-TNFa treatment showed good efficacy and safety in anti-Ro/SSA positive patients with RA. Anti-ds- DNA antibodies at low titer appeared in most patients while the onset of lupus-like disease could be considered a rare event also in RA patients with a rich autoimmune repertoire.

  12. Elevated IL-1β levels in anti-Ro/SSA connective tissue diseases patients with prolonged corrected QTc interval.

    Science.gov (United States)

    Pisoni, Cecilia N; Reina, Silvia; Arakaki, Diego; Eimon, Alicia; Carrizo, Carolina; Borda, Enri

    2015-01-01

    Patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) have increased IL-1β levels. IL-1β and other pro-inflammatory cytokines have a modulating activity on cardiac ion channels and have been associated with increased arrhythmic risk in rheumatoid arthritis patients. Likewise, adult patients with connective tissue diseases (CTDs) may have prolonged QTc intervals associated with the presence of anti-Ro/SSA antibodies. Our objective was to evaluate the presence of serum IL-1β in subjects with CTDs, in relation to the presence of anti-Ro/SSA antibodies and QTc interval duration. 12-lead electrocardiograms (ECG) were performed and blood was withdrawn, measuring electrolytes, IL-1β anti-Ro/SSA antibodies by ELISA in 73 patients with CTDs. 55 patients were anti-Ro/SSA positive and 18 were anti-Ro/SSA negative. Patients with anti-Ro/SSA positive antibodies had a significantly greater median IL-1β serum level: 7.29 (range: 0.17-17.3 pg/ml) compared to patients with anti-Ro/SSA negative antibodies whose median was: 1.67 (range 0.55-4.12 pg/ml) pRo/SSA positive versus 0 (0 %) in anti-Ro/SSA negative patients p=0.05. Median IL-1β levels were: 8.7 (range: 2.69-15.1 pg/ml) in patients with prolonged QTc interval versus median: 5.0 (range: 0.17-17.3 pg/ml) in those with normal QTc interval values (Ro/SSA antibodies and prolonged QTc intervals.

  13. Anti-Ro/SSA antibodies are associated with severe mitral valve regurgitation in patients with systemic lupus erythematosus.

    Science.gov (United States)

    Higuera-Ortiz, Violeta; Mora-Arias, Tania; Castillo-Martinez, Diana; Amezcua-Guerra, Luis M

    2017-05-01

    To assess whether anti-Ro/SSA antibodies are associated with cardiac valve disease in lupus. A single-center, medical chart review was performed. Lupus patients were divided according to its anti-Ro/SSA status and subgroups were compared for valvular abnormalities and other characteristics. Dependence of anti-Ro/SSA reactivity to anti-Ro52/TRIM21 antibodies was also evaluated. Eighty-nine lupus patients were analyzed. The most common valvular abnormalities were tricuspid (60%), mitral (41%) and pulmonary (14%) regurgitation. Thirty-six patients were positive and 53 negative for anti-Ro/SSA antibodies. In patients positive to anti-Ro/SSA, a difference was noted for anti-dsDNA (67 versus 45%; p = 0.04) and anti-La/SSB (19 versus 2%; p = 0.004) antibodies. An association between anti-Ro/SSA antibodies and severe mitral regurgitation was observed; indeed, 4/15 patients with anti-Ro/SSA and mitral regurgitation had severe forms of valvulopathy as compared to only 1/22 patients with mitral regurgitation but negative to such antibody (27 versus 5%; p = 0.02). Anti-Ro/SSA antibodies significantly elevated the risk of severe mitral regurgitation (OR = 5). Anti-Ro52/TRIM21 levels (103 ± 29 versus 42 ± 43 U/mL; p = 0.03) and anti-Ro52/TRIM21: anti-Ro/SSA ratios (0.88 ± 0.02 versus 0.35 ± 0.37; p = 0.03) were higher in patients with mitral valve regurgitation than in those with no valvulopathy. Anti-Ro/SSA antibodies, mainly against Ro52/TRIM21 antigens, may be pathologically involved in lupus-associated mitral valve regurgitation.

  14. Size and Albedo of Irregular Saturnian Satellites from Spitzer Observations

    NARCIS (Netherlands)

    Mueller, Michael; Grav, T.; Trilling, D.; Stansberry, J.; Sykes, M.

    2008-01-01

    Using MIPS onboard the Spitzer Space Telescope, we observed the thermal emission (24 and, for some targets, 70 um) of eight irregular satellites of Saturn: Albiorix, Siarnaq, Paaliaq, Kiviuq, Ijiraq, Tarvos, Erriapus, and Ymir. We determined the size and albedo of all targets. An analysis of

  15. Surface albedo following biochar application in durum wheat

    International Nuclear Information System (INIS)

    Genesio, L; Miglietta, F; Lugato, E; Baronti, S; Pieri, M; Vaccari, F P

    2012-01-01

    The agronomic use of charcoal from biomass pyrolysis (biochar) represents an interesting option for increasing soil fertility and sequestering atmospheric CO 2 . However, before moving toward large-scale biochar applications, additional research must evaluate all possible land–atmosphere feedbacks. Despite the increasing number of studies investigating the effect of biochar on soil physical, chemical and biological properties, only a few have been done on surface albedo variations on agricultural lands. The present work had the aim of characterizing the annual albedo cycle for a durum wheat crop in Central Italy, by means of a spectroradiometer measurement campaign. Plots treated with biochar, at a rate of 30–60 t ha −1 , showed a surface albedo decrease of up to 80% (after the application) with respect to the control in bare soil conditions, while this difference tended to decrease during the crop growing season, because of the prevailing effect of canopy development on the radiometer response. After the post-harvesting tillage, the soil treated with biochar again showed a lower surface albedo value (<20–26% than the control), while the measurements taken in the second year after application suggested a clear decrease of biochar influence on soil color. The modeling of the surface energy balance highlighted changes in the partitioning of heat fluxes and in particular a substantial increase of ground heat fluxes on an annual basis. (letter)

  16. Mimicking biochar-albedo feedback in complex Mediterranean agricultural landscapes

    International Nuclear Information System (INIS)

    Bozzi, E; Genesio, L; Miglietta, F; Toscano, P; Pieri, M

    2015-01-01

    Incorporation of charcoal produced by biomass pyrolysis (biochar) in agricultural soils is a potentially sustainable strategy for climate change mitigation. However, some side effects of large-scale biochar application need to be investigated. In particular a massive use of a low-reflecting material on large cropland areas may impact the climate via changes in surface albedo. Twelve years of MODIS-derived albedo data were analysed for three pairs of selected agricultural sites in central Italy. In each pair bright and dark coloured soil were identified, mimicking the effect of biochar application on the land surface albedo of complex agricultural landscapes. Over this period vegetation canopies never completely masked differences in background soil colour. This soil signal, expressed as an albedo difference, induced a local instantaneous radiative forcing of up to 4.7 W m −2 during periods of high solar irradiance. Biochar mitigation potential might therefore be reduced up to ∼30%. This study proves the importance of accounting for crop phenology and crop management when assessing biochar mitigation potential and provides more insights into the analysis of its environmental feedback. (letter)

  17. The retrieval of land surface albedo in rugged terrain

    NARCIS (Netherlands)

    Gao, B.; Jia, L.; Menenti, M.

    2012-01-01

    Land surface albedo may be derived from the satellite data through the estimation of a bidirectional reflectance distribution function (BRDF) model and angular integration. However many BRDF models do not consider explicitly the topography. In rugged terrain, the topography influences the observed

  18. Summertime canopy albedo is sensitive to forest thinning

    NARCIS (Netherlands)

    Otto, J.; Berveiller, D.; Bréon, F.M.; Delpierre, N.; Geppert, G.; Granier, A.; Jans, W.W.P.; Knohl, A.; Moors, E.J.

    2013-01-01

    Despite an emerging body of literature linking canopy albedo to forest management, understanding of the process is still fragmented. We combined a stand-level forest gap model with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning,

  19. The effect of surface albedo and grain size distribution on ...

    African Journals Online (AJOL)

    Sand dams are very useful in arid and semi arid lands (ASALs) as facilities for water storage and conservation. Soils in ASALs are mainly sandy and major water loss is by evaporation and infiltration. This study investigated the effect of sand media characteristics, specifically surface albedo, grain size and stratification on ...

  20. Model test of CCN-cloud albedo climate forcing

    Science.gov (United States)

    Ghan, S. J.; Taylor, K. E.; Penner, J. E.; Erickson, D. J., III

    1990-01-01

    Cloud condensation nuclei (CCN) influence cloud albedo through their effect on the cloud droplet size distribution. A number of studies have evaluated the climatic impact of the CCN-cloud albedo feedback, but all have assumed that cloud distributions, cloud thicknesses, and cloud liquid water contents would remain constant as the climate adjusted. This assumption has been tested using the Livermore version of the National Center for Atmospheric Research Community Climate Model. The results indicate that there are no significant compensating changes in cloud properties that would counteract the 1.7 percent global albedo increase resulting from a fourfold increase in marine CCN concentration. Furthermore, when ocean surface temperatures are decreased 4 C in a manner broadly consistent with the enhanced cloud albedos, an increase in cloud fraction of 3.5 percent and a reduction in cloud altitude are predicted, leading to a positive feedback from clouds that would imply a climate impact roughly double that calculated from cloud droplet size distribution change alone.

  1. Effect of urban albedo surfaces on thermal comfort | Mansouri ...

    African Journals Online (AJOL)

    It turns out that the reflectivity of materials known as the albedo, plays a leading role in this degradation. A numerical study was carried out to assess the thermal comfort of citizens by applying reflective materials for roofs, facades and floor. The results show that the reflective light paints help in moderating the microclimate, ...

  2. Forests, nitrogen and albedo, a very interesting trio indeed

    Directory of Open Access Journals (Sweden)

    Borghetti M

    2009-01-01

    Full Text Available A short comment is made on a recent paper (Ollinger et al. 2008 which shows that forest ecosystem carbon uptake in temperate and boreal forests is directly related to canopy nitrogen concentration and that both carbon uptake capacity and canopy nitrogen concentration are positively correlated with shortwave surface albedo measured with broad-band satellite sensors.

  3. Albedo and color maps of the Saturnian satellites

    International Nuclear Information System (INIS)

    Buratti, B.J.; Mosher, J.A.; Johnson, T.V.

    1990-01-01

    The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites. 67 refs

  4. Multidecadal analysis of forest growth and albedo in boreal Finland

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Petr; Stenberg, P.; Mottus, M.; Manninen, T.; Rautiainen, M.

    2016-01-01

    Roč. 52, OCT (2016), s. 296-305 ISSN 0303-2434 R&D Projects: GA MŠk(CZ) LM2010007; GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : Albedo * fAPAR * LAI * NDVI * Time series * Seasonal trends * Forest structure Subject RIV: EH - Ecology, Behaviour Impact factor: 3.930, year: 2016

  5. MISR Level 3 FIRSTLOOK Component Global Albedo product covering a day V002

    Data.gov (United States)

    National Aeronautics and Space Administration — The MISR Level 3 FIRSTLOOK Component Global Albedo Product covering a day contains a statistical summary of column albedo 555 nanometer optical depth, and a monthly...

  6. MISR Level 3 FIRSTLOOK Component Global Albedo product covering a month V002

    Data.gov (United States)

    National Aeronautics and Space Administration — The MISR Level 3 FIRSTLOOK Component Global Albedo Product covering a monthly contains a statistical summary of column albedo 555 nanometer optical depth, and a...

  7. ISLSCP II Snow-Free, Spatially Complete, 16 Day Albedo, 2002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, ISLSCP II Snow-Free, Spatially Complete, 16 Day Albedo, 2002, contains 9 files for snow-free, spatially complete 16-day global black-sky albedos at...

  8. ISLSCP II Snow-Free, Spatially Complete, 16 Day Albedo, 2002

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains 9 files for snow-free, spatially complete 16-day global black-sky albedos at local solar noon, white-sky albedos and quality...

  9. ISLSCP II Snow-Free, Spatially Complete, 16 Day Albedo, 2002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 9 files for snow-free, spatially complete 16-day global black-sky albedos at local solar noon, white-sky albedos and quality information based...

  10. SAFARI 2000 MODIS L3 Albedo and Land Cover Data, Southern Africa, Dry Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — The Filled Land Surface Albedo Product for Southern Africa, which is generated from MOD43B3 Product (the official Terra/MODIS-derived Land Surface Albedo -...

  11. NLCD - MODIS land cover- albedo dataset for the continental United States

    Data.gov (United States)

    U.S. Environmental Protection Agency — The NLCD-MODIS land cover-albedo database integrates high-quality MODIS albedo observations with areas of homogeneous land cover from NLCD. The spatial resolution...

  12. SAFARI 2000 MODIS L3 Albedo and Land Cover Data, Southern Africa, Dry Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The Filled Land Surface Albedo Product for Southern Africa, which is generated from MOD43B3 Product (the official Terra/MODIS-derived Land Surface Albedo -...

  13. Snow cover and vegetation-induced decrease in global albedo from 2002 to 2016

    OpenAIRE

    Li, Qiuping; Ma, Mingguo; Wu, Xiaodan; Yang, Hong

    2018-01-01

    Land surface albedo is an essential parameter in regional and global climate models, and it is markedly influenced by land cover change. Variations in the albedo can affect the surface radiation budget and further impact the global climate. In this study, the interannual variation of albedo from 2002 to 2016 was estimated on the global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) datasets. The presence and causes of the albedo changes for each specific region were also ex...

  14. A statistics-based temporal filter algorithm to map spatiotemporally continuous shortwave albedo from MODIS data

    Directory of Open Access Journals (Sweden)

    N. F. Liu

    2013-06-01

    Full Text Available Land-surface albedo plays a critical role in the earth's radiant energy budget studies. Satellite remote sensing provides an effective approach to acquire regional and global albedo observations. Owing to cloud coverage, seasonal snow and sensor malfunctions, spatiotemporally continuous albedo datasets are often inaccessible. The Global LAnd Surface Satellite (GLASS project aims at providing a suite of key land surface parameter datasets with high temporal resolution and high accuracy for a global change study. The GLASS preliminary albedo datasets are global daily land-surface albedo generated by an angular bin algorithm (Qu et al., 2013. Like other products, the GLASS preliminary albedo datasets are affected by large areas of missing data; beside, sharp fluctuations exist in the time series of the GLASS preliminary albedo due to data noise and algorithm uncertainties. Based on the Bayesian theory, a statistics-based temporal filter (STF algorithm is proposed in this paper to fill data gaps, smooth albedo time series, and generate the GLASS final albedo product. The results of the STF algorithm are smooth and gapless albedo time series, with uncertainty estimations. The performance of the STF method was tested on one tile (H25V05 and three ground stations. Results show that the STF method has greatly improved the integrity and smoothness of the GLASS final albedo product. Seasonal trends in albedo are well depicted by the GLASS final albedo product. Compared with MODerate resolution Imaging Spectroradiometer (MODIS product, the GLASS final albedo product has a higher temporal resolution and more competence in capturing the surface albedo variations. It is recommended that the quality flag should be always checked before using the GLASS final albedo product.

  15. Albedo of a hybrid poplar plantation in central Alberta, Canada

    Science.gov (United States)

    Price, D. T.; Bernier, P. Y.; Orchansky, A.; Thomas, B.

    2012-04-01

    Canada's boreal forest resources are coming under increasing pressure from competing land-uses, including establishment of protected areas, and losses of harvestable forest to mining and oil and gas exploration. In the prairie region, concerns about lack of wood supply for pulpmills and potential opportunities for bioenergy production and carbon sequestration for climate change mitigation, have spurred interest in afforestation of marginal agricultural land, notably with fast-growing hybrid poplars (HP). However, global modelling studies suggest that a shift from grassland or crops to forest cover in temperate and boreal regions could result in reduced surface albedo, particularly in winter, causing an increase in radiative forcing and reducing any climate mitigation benefits due to net GHG removal. We report on seven growing seasons of measurements of short-wave canopy albedo using tower-mounted instruments, along with eddy covariance measurements of carbon, water and energy balance, at a site in central Alberta planted with HP cuttings in spring 2005. The data show little systematic change in average albedo as vegetation has changed from bare ground to a plantation of 6 m trees. Reasons for this include very wide (3 m) spacing between the trees, and snow cover which often persists for 4-5 months and is highly visible below the bare canopies during winter. While measurements should continue as the trees grow larger, we postulate that extensive afforestation with HP is unlikely to have major effects on regional-scale surface albedo compared to the agricultural systems they replace. Normal rotation lengths are 15-20 years, hence even if older plantations have significantly lower winter albedo, their contribution to the regional average would be relatively small because they will cover only a small fraction of the landscape (e.g., compared to forests of boreal conifers or temperate broadleaved species).

  16. Effect of land cover change on snow free surface albedo across the continental United States

    Science.gov (United States)

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-&t...

  17. MODIS/Terra+Aqua BRDF/Albedo Albedo Daily L3 Global 0.05Deg CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS MCD43C3 Version 6 Albedo Model data set is a 5600 meter daily 16-day product. The Julian date in the granule ID of each specific file represents the 9th...

  18. Understanding Large-scale Structure in the SSA22 Protocluster Region Using Cosmological Simulations

    Science.gov (United States)

    Topping, Michael W.; Shapley, Alice E.; Steidel, Charles C.; Naoz, Smadar; Primack, Joel R.

    2018-01-01

    We investigate the nature and evolution of large-scale structure within the SSA22 protocluster region at z = 3.09 using cosmological simulations. A redshift histogram constructed from current spectroscopic observations of the SSA22 protocluster reveals two separate peaks at z = 3.065 (blue) and z = 3.095 (red). Based on these data, we report updated overdensity and mass calculations for the SSA22 protocluster. We find {δ }b,{gal}=4.8+/- 1.8 and {δ }r,{gal}=9.5+/- 2.0 for the blue and red peaks, respectively, and {δ }t,{gal}=7.6+/- 1.4 for the entire region. These overdensities correspond to masses of {M}b=(0.76+/- 0.17)× {10}15{h}-1 {M}ȯ , {M}r=(2.15+/- 0.32)× {10}15{h}-1 {M}ȯ , and {M}t=(3.19+/- 0.40)× {10}15{h}-1 {M}ȯ for the red, blue, and total peaks, respectively. We use the Small MultiDark Planck (SMDPL) simulation to identify comparably massive z∼ 3 protoclusters, and uncover the underlying structure and ultimate fate of the SSA22 protocluster. For this analysis, we construct mock redshift histograms for each simulated z∼ 3 protocluster, quantitatively comparing them with the observed SSA22 data. We find that the observed double-peaked structure in the SSA22 redshift histogram corresponds not to a single coalescing cluster, but rather the proximity of a ∼ {10}15{h}-1 {M}ȯ protocluster and at least one > {10}14{h}-1 {M}ȯ cluster progenitor. Such associations in the SMDPL simulation are easily understood within the framework of hierarchical clustering of dark matter halos. We finally find that the opportunity to observe such a phenomenon is incredibly rare, with an occurrence rate of 7.4{h}3 {{{Gpc}}}-3. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.

  19. Retrieving the Height of Smoke and Dust Aerosols by Synergistic Use of Multiple Satellite Sensors

    Science.gov (United States)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2016-01-01

    The Aerosol Single scattering albedo and Height Estimation (ASHE) algorithm was first introduced in Jeong and Hsu (2008) to provide aerosol layer height and single scattering albedo (SSA) for biomass burning smoke aerosols. By using multiple satellite sensors synergistically, ASHE can provide the height information over much broader areas than lidar observations alone. The complete ASHE algorithm uses aerosol data from MODIS or VIIRS, OMI or OMPS, and CALIOP. A simplified algorithm also exists that does not require CALIOP data as long as the SSA of the aerosol layer is provided by another source. Several updates have recently been made: inclusion of dust layers in the retrieval process, better determination of the input aerosol layer height from CALIOP, improvement in aerosol optical depth (AOD) for nonspherical dust, development of quality assurance (QA) procedure, etc.

  20. Multiplatform observations enabling albedo retrievals with high temporal resolution

    Science.gov (United States)

    Riihelä, Aku; Manninen, Terhikki; Key, Jeffrey; Sun, Qingsong; Sütterlin, Melanie; Lattanzio, Alessio; Schaaf, Crystal

    2017-04-01

    In this paper we show that combining observations from different polar orbiting satellite families (such as AVHRR and MODIS) is physically justifiable and technically feasible. Our proposed approach will lead to surface albedo retrievals at higher temporal resolution than the state of the art, with comparable or better accuracy. This study is carried out in the World Meteorological Organization (WMO) Sustained and coordinated processing of Environmental Satellite data for Climate Monitoring (SCOPE-CM) project SCM-02 (http://www.scope-cm.org/projects/scm-02/). Following a spectral homogenization of the Top-of-Atmosphere reflectances of bands 1 & 2 from AVHRR and MODIS, both observation datasets are atmospherically corrected with a coherent atmospheric profile and algorithm. The resulting surface reflectances are then fed into an inversion of the RossThick-LiSparse-Reciprocal surface bidirectional reflectance distribution function (BRDF) model. The results of the inversion (BRDF kernels) may then be integrated to estimate various surface albedo quantities. A key principle here is that the larger number of valid surface observations with multiple satellites allows us to invert the BRDF coefficients within a shorter time span, enabling the monitoring of relatively rapid surface phenomena such as snowmelt. The proposed multiplatform approach is expected to bring benefits in particular to the observation of the albedo of the polar regions, where persistent cloudiness and long atmospheric path lengths present challenges to satellite-based retrievals. Following a similar logic, the retrievals over tropical regions with high cloudiness should also benefit from the method. We present results from a demonstrator dataset of a global combined AVHRR-GAC and MODIS dataset covering the year 2010. The retrieved surface albedo is compared against quality-monitored in situ albedo observations from the Baseline Surface Radiation Network (BSRN). Additionally, the combined retrieval

  1. Upwelling UV spectral irradiances and surface albedo measurements at Lauder, New Zealand

    Science.gov (United States)

    McKenzie, R. L.; Kotkamp, M.; Ireland, W.

    Simultaneous measurements of upwelling and downwelling ultraviolet (UV) spectral irradiance were used to deduce the wavelength dependence and the solar zenith angle dependence of the albedo of the ground surface (long grass) at Lauder, New Zealand (45.05°S, 169.68°E). In the UVB region the deduced albedos are approximately 1%. At longer wavelengths the albedo increases to approximately 2% at 400 nm, and 4.5% at 450 nm. These albedos are significantly smaller than those generally quoted for the visible region. The deduced albedos tend to increase at larger solar zenith angles, demonstrating that the surface is not strictly Lambertian.

  2. Sensitivity of mountain glacier mass balance to changes in bare-ice albedo

    OpenAIRE

    Naegeli, Kathrin; Huss, Matthias

    2017-01-01

    Albedo is an important parameter in the energy balance of bare-ice surfaces and modulates glacier melt rates. The prolongation of the ablation period enforces the albedo feedback and highlights the need for profound knowledge on impacts of bare-ice albedo on glacier mass balance. In this study, we assess the mass balance sensitivity of 12 Swiss glaciers with abundant long-term in-situ data on changes in bare-ice albedo. We use pixel-based bare-ice albedo derived from Landsat 8. A distributed ...

  3. Joint AGU/SSA Statement on the Comprehensive Test Ban Treaty

    Science.gov (United States)

    Lanzerotti, Louis J.

    Recognizing that the debate in the U.S. Senate on whether to ratify the Comprehensive Test Ban Treaty (CTBT) could benefit from a clear analysis of the technical limits to monitoring nuclear explosions, AGU joined with the Seismological Society of America (SSA) to carry out such an analysis. In the following policy statement, approved by both societies, seismologists speak with essentially one voice about this crucial aspect of the CTBT. This is the first time that AGU has prepared a policy statement jointly with another society, and this is the first policy statement SSA has adopted.The policy regarding AGU's procedures for developing position statements on public issues, the Union's role in advocacy of the statements, and all current AGU position statements are available online at http://www.agu. org/sci_soc/policy/sci_ pol.html.

  4. Effect of land cover change on snow free surface albedo across the continental United States

    Science.gov (United States)

    Wickham, J.; Nash, M.S.; Barnes, Christopher A.

    2016-01-01

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-×-30 m) land cover change data and moderate resolution (~ 500 m-×-500 m) albedo data. The land cover change data spanned 10 years (2001 − 2011) and the albedo data included observations every eight days for 13 years (2001 − 2013). Empirical testing was based on autoregressive time series analysis of snow free albedo for verified locations of land cover change. Approximately one-third of the autoregressive analyses for woody to herbaceous or forest to shrub change classes were not significant, indicating that albedo did not change significantly as a result of land cover change at these locations. In addition, ~ 80% of mean differences in albedo arising from land cover change were less than ± 0.02, a nominal benchmark for precision of albedo measurements that is related to significant changes in radiative forcing. Under snow free conditions, we found that land cover change does not guarantee a significant albedo response, and that the differences in mean albedo response for the majority of land cover change locations were small.

  5. Close packing effects on clean and dirty snow albedo and associated climatic implications

    Science.gov (United States)

    He, Cenlin; Takano, Yoshi; Liou, Kuo-Nan

    2017-04-01

    Previous modeling of snow albedo, a key climate feedback parameter, follows the independent scattering approximation (ISA) such that snow grains are considered as a number of separate units with distances longer than wavelengths. Here we develop a new snow albedo model for widely observed close-packed snow grains internally mixed with black carbon (BC) and demonstrate that albedo simulations match closer to observations. Close packing results in a stronger light absorption for clean and BC-contaminated snow. Compared with ISA, close packing reduces pure snow albedos by up to 0.05, whereas it enhances BC-induced snow albedo reduction and associated surface radiative forcing by up to 15% (20%) for fresh (old) snow, with larger enhancements for stronger structure packing. Finally, our results suggest that BC-snow albedo forcing and snow albedo feedback (climate sensitivity) are underestimated in previous modeling studies, making snow close packing consideration a necessity in climate modeling and analysis.

  6. Factors influencing fetal cardiac conduction in anti-Ro/SSA-positive pregnancies.

    Science.gov (United States)

    Sonesson, Sven-Erik; Hedlund, Malin; Ambrosi, Aurélie; Wahren-Herlenius, Marie

    2017-10-01

    Congenital heart block (CHB) develops in 1-2% of anti-Ro/SSA-positive pregnancies and has a recurrence rate of 12-20%, which indicates that factors other than maternal autoantibodies are crucial for CHB to occur. Here, we aimed to evaluate the influence of factors previously associated with CHB on the occurrence of milder forms of fetal cardiac conduction disturbances, shown to occur in up to 30% of anti-Ro/SSA-positive pregnancies, and on neonatal outcome in a large cohort of prospectively followed pregnancies. The association of maternal age, season of the year and history of atrioventricular block (AVB) with the development of fetal Doppler and neonatal ECG conduction disturbances was evaluated in 212 anti-Ro52/SSA-positive singleton pregnancies. Maternal age was significantly higher in AVB II-III pregnancies but was not correlated with fetal AV time intervals in fetuses without signs of AVB II-III. AV time intervals of fetuses surveilled during the winter were significantly longer than those of fetuses surveilled during the summer. Fetal AV time intervals in consecutive pregnancies from the same women were significantly correlated. A history of AVB II-III was associated with significantly longer AV time intervals, and AVB I-III was observed at birth in 38% of babies born after a sibling with abnormal fetal AV conduction. Our study shows that AV time intervals in anti-Ro/SSA antibody-exposed fetuses during the CHB risk period are influenced by the season of the year, and reveals that the recurrence of conduction disturbances in antibody-exposed fetuses is higher than previously reported when milder forms are taken into account. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  7. Albedo decreasing trend. White cars proposal and new urban scenarios

    Directory of Open Access Journals (Sweden)

    Niccolò Casiddu

    2014-05-01

    Full Text Available Global warming caused the decrease of the albedo. Emission reduction is the most widely proposed response to this problem. However simple ideas such as cool roofs and cool pavements seem successful remedies to counter the threat. However in Italy another strategy appears more effective. By changing from dark to pastel bright automotive colours a considerable increase of the albedo can be hypothesized: the effect should be from 32% to 50% of the results obtained with an extensive application of the “cool roofs” strategy. Such a proposal involves the creation of new, unexpected cityscapes. The city is a place where the perception of space changes. The car, by definition is an object in motion, but still present, sometimes redundant in the urban landscape. What will be the perceived relationship with buildings, streets, squares where the cars are all white or pastel colour?

  8. Comparison of MCNPX and Albedo method in criticality calculation

    International Nuclear Information System (INIS)

    Cunha, Victor L. Lassance; Rebello, Wilson F.; Cabral, Ronaldo G.; Melo, Fernando da S.; Silva, Ademir X. da

    2009-01-01

    This study aims to conduct a computer simulation that will calculate the reactivity of a homogeneous reactor and compare the results with the calculations made by the albedo method. The simulation will be developed using the MCNPX. The study compared the results calculated for a hypothetical reactor by the albedo method for four groups of energy with those obtained by the MCNPX simulation. The design of the reactor is spherical and homogeneous with a reflector of finite thickness. The value obtained for the neutron effective multiplication factor - k eff will be compared. Different situations were simulated in order to obtain results closer to the compared method and reality. The was Good consistency could be noticed between the calculated results. (author)

  9. Evaluation of Regional Climatic Model Simulated Aerosol Optical Properties over South Africa Using Ground-Based and Satellite Observations

    OpenAIRE

    Tesfaye, M.; Botai, J.; Sivakumar, V.; Mengistu Tsidu, G.

    2013-01-01

    The present study evaluates the aerosol optical property computing performance of the Regional Climate Model (RegCM4) which is interactively coupled with anthropogenic-desert dust schemes, in South Africa. The validation was carried out by comparing RegCM4 estimated: aerosol extinction coefficient profile, Aerosol Optical Depth (AOD), and Single Scattering Albedo (SSA) with AERONET, LIDAR, and MISR observations. The results showed that the magnitudes of simulated AOD at the Skukuza station (2...

  10. Colour, albedo and nucleus size of Halley's comet

    Science.gov (United States)

    Cruikshank, D. P.; Tholen, D. J.; Hartmann, W. K.

    1985-01-01

    Photometry of Halley's comet in the B, J, V, and K broadband filters during a time when the coma was very weak and presumed to contribute negligibly to the broadband photometry is reported. The V-J and J-K colors suggest that the color of the nucleus of Halley's comet is similar to that of the D-type asteroids, which in turn suggests that the surface of the nucleus has an albedo less than 0.1.

  11. PENGAMBILAN PEKTIN DARI ALBEDO SEMANGKA DENGAN PROSES EKSTRAKSI ASAM

    Directory of Open Access Journals (Sweden)

    Melisa Triandini Maulani

    2014-04-01

    Full Text Available Watermelon is a plant that is resistant to dry climate so it can be grown in tropical and semi-desert. Watermelon albedo is a potential source of pectin because it contains pectin compounds. To decompose the pectin in the watermelon albedo can be done by acid extraction process because it will lesser the possibility of damage pectin, whereas alcohol is use to precipitate pectin. In this research watermelon albedo as basic ingredients would be extracted to produce pectin to identified the differences in the influence of temperature variation and the type of solvent extraction of the pectin content of the albedo watermelon and determined variations in maximum temperature and type of solvent extraction to produce pectin. The study was conducted with a 90-minute extraction time and extraction temperature 60, 70, and 80 °C and 500 mL the solvent HCl and CH3COOH with 2.6 pH. The results were obtained taking the maximum conditions of pectin using solvent extraction HCl at a temperature of 80 °C and obtained pectin levels of 11.2635%. Solvent which is a strong acid HCl is easier to untie protopektin pectin so pectin levels has generated a high level. The higher the operating temperature, the bigger pectin levels that are obtained until the temperature limit of 80 °C. This caused by the movement of the H+ ions more reactive, the more contact between the substances dissolved in the sample with solvent and obtained more pectin.

  12. Rapid assessment of populations trends of invasive species: Singular Spectrum Analysis (SSA

    Directory of Open Access Journals (Sweden)

    DANA, ED

    2010-01-01

    Full Text Available Singular Spectrum Analysis (SSA is a powerful analytical approach for biodi-versity management. Its main advan-tages are due to its intuitive processing and visualization, since mathematical workflow is conceptually similar to the widely accepted Principal Components Analysis. Detailed analyses of popula-tion trends with mathematical tools are often difficult to achieve for managers by a number of reasons (large numbers or areas monitored, large number of species, insufficient statistics skills, strong knowledge level in demographic analyses, etc.. SSA has been used since the 1970’s in signal processing to clarify signal vs. noisy information, but it has also been used in climate change analy-sis and other developmental areas. Be-sides, SSA is a rapid-learning method for technicians and managers with medium level of mathematical knowledge. Free software in Unix environment is avail-able. Unfortunately, no free and friendly software is available for Win-dows SO. Although R package may offer solutions for really advanced users, it does not fit real work situations for managers of biological invasions. Cater-pillar (Gistat Group, Ltd is by now, the best option found by the author in terms of price, facility for results inter-pretation and time consumed in learn-ing. The main disadvantage is the poor content of tutorial files

  13. Sewage sludge ash (SSA in high performance concrete: characterization and application

    Directory of Open Access Journals (Sweden)

    C. M. A. Fontes

    Full Text Available ABSTRACT Sewage sludge originated from the process of treatment of wastewater has become an environmental issue for three main reasons: contains pathogens, heavy metals and organic compounds that are harmful to the environmental and human health; high volumes are daily generated; and shortage of landfill sites for proper disposal. This research deals with the viability study of sewage sludge utilization, after calcination process, as mineral admixture in the production of concrete. High-performance concretes were produced with replacement content of 5% and 10% by weight of Portland cement with sewage sludge ash (SSA. The influence of this ash was analyzed through physical and mechanical tests. Analysis showed that the mixtures containing SSA have lower values of compressive strength than the reference. The results of absorptivity, porosity and accelerated penetration of chloride ions, presents that mixtures containing ash showed reductions compared to the reference. This indicates that SSA provided refinement of the pore structure, which was confirmed by mercury intrusion porosimetry test.

  14. Gamma-ray Albedo of Small Solar System Bodies

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, I.V.

    2008-03-25

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For details of our calculations and references see [1].

  15. Signatures of Volatiles in the Lunar Proton Albedo

    Science.gov (United States)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; hide

    2015-01-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  16. Assessing the possibility of a runaway ice-albedo feedback

    Science.gov (United States)

    Eisenman, I.

    2012-12-01

    If the ice-albedo feedback becomes dominant in high latitudes at some point as the climate warms, a runaway feedback will ensue in which the climate transitions to a new state. Such a transition occurs at a bifurcation point and is characterized by a discontinuity in the stable states available to the climate system. The possibility of such a runaway feedback in the Arctic has been investigated previously in a number of studies using both single-column models and comprehensive global models, and they have produced widely differing results. Here, I will use a toy model to evaluate the varied previously published results. The toy model represents the physics of sea ice growth and melt below a single column of the atmosphere, and the strength of interacting climate feedbacks such as albedo, clouds, and water vapor are controlled by scalable parameters. The toy model results suggest a novel measure, which can be assessed based on the current climate state, of how prone to instability the sea ice cover will be under global warming. I will demonstrate this measure in simulations from two state-of-the-art climate models, one of which has been shown to simulate a runaway ice-albedo feedback in the Arctic climate response to substantial greenhouse forcing and the other of which has been shown not to. This measure, which is based only on the simulated 20th century climate in each model, correctly identifies the model more prone to Arctic sea ice instability under substantial global warming.

  17. SSA DISABILITY. SGA Levels Appear to Affect the Work Behavior of Relatively Few Beneficiaries, but More Data Needed

    National Research Council Canada - National Science Library

    Baucus, Max

    2002-01-01

    ... physical or mental impairment has earnings that exceed the Substantial Gainful Activity (SGA) level, which represents SSA's principal standard for determining whether a disabled individual is able to work...

  18. Distinguishing the albedo of exoplanets from stellar activity

    Science.gov (United States)

    Serrano, L. M.; Barros, S. C. C.; Oshagh, M.; Santos, N. C.; Faria, J. P.; Demangeon, O.; Sousa, S. G.; Lendl, M.

    2018-03-01

    Context. Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal. Aims: We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the obervations planned in the context of the CHEOPS mission. Methods: As initial condition, we have assumed that each star is characterized by just one orbiting planet. We built mock light curves that included a realistic stellar activity pattern, the reflected light component of the planet and an instrumental noise level, which we have chosen to be at the same level as predicted for CHEOPS. We then fit these light curves to try to recover the reflected light component, assuming the activity patterns can be modeled with a Gaussian process. Results: We estimate that at least one full stellar rotation is necessary to obtain a reliable detection of the planetary albedo. This result is independent of the level of noise, but it depends on the limitation of the Gaussian process to describe the stellar activity when the light curve time-span is shorter than the stellar rotation. As an additional result, we found that with a 6.5 magnitude star and the noise level of CHEOPS, it is possible to detect the planetary albedo up to a lower limit of Rp = 0.03 R*. Finally, in presence of typical CHEOPS gaps in the simulations, we confirm that it is still possible to obtain a reliable albedo.

  19. The East Asian Development Experience: Policy Lessons, Implications, and Recommendations for Sub-Saharan Africa (SSA) Global Competitiveness

    OpenAIRE

    Ashford C. Chea

    2012-01-01

    The paper looks at the development experience of East Asia and draws lessons for Sub-Saharan Africa in building global competitiveness. It starts with a historical perspective of both regions’ developmental trajectories. This is followed by an analysis of the causes of East Asia’s superior economic performance and development and SSA underdevelopment. The article also draws policy lessons from East Asia development strategies for SSA global competitiveness. The paper ends with a presentation ...

  20. SSa ameliorates the Glu uptaking capacity of astrocytes in epilepsy via AP-1/miR-155/GLAST.

    Science.gov (United States)

    Gao, Wei; Bi, Yongfeng; Ding, Li; Zhu, Weiwei; Ye, Ming

    2017-11-25

    Neuronal glutamate (Glu) release has been reported to mediate the neuronal injury of epilepsy, while Saikosaponin a (Ssa) was shown to ameliorate the epilepsy that induced by pentylenetetrazol (PTZ). However, potential interactions between glutamate release and Ssa has not been fully identified. Herein, PTZ-induced rat model were established to evaluate the neuron injury, while Ssa was used to treat the model rat. Rat astrocytes were isolated and induced by PTZ to construct cell models of epilepsy, real-time PCR and western blot were used to determine genes' expression. Luciferase reporter assay were performed to validate the relationship between miR-155-5p and glutamate aspartate transporter (GLAST). The level of Glu was sampled for HPLC measurement. Ssa treatment could decrease the level of Glu in hippocampus of rat. PTZ-induced astrocytes pretreated with Ssa significantly decreased the expression of AP-1 and miR-155, but increased the expression of GLAST, furthermore, PTZ stimulation enables astrocytes to uptake large amount of extracellular Glu. AP-1 could bind with the promoter of miR-155 to promote its transcription. MiR-155 tragets GLAST to govern its expression. Ssa treatment played pivotal roles in PTZ-induced epilepsy by promoting the expression of GLAT1 and uptaking of Glu, which was mediated by the expression of AP-1 and miR-155. Copyright © 2017. Published by Elsevier Inc.

  1. Land Surface Albedo Estimation from Chinese HJ Satellite Data Based on the Direct Estimation Approach

    Directory of Open Access Journals (Sweden)

    Tao He

    2015-05-01

    Full Text Available Monitoring surface albedo at medium-to-fine resolution (<100 m has become increasingly important for medium-to-fine scale applications and coarse-resolution data evaluation. This paper presents a method for estimating surface albedo directly using top-of-atmosphere reflectance. This is the first attempt to derive surface albedo for both snow-free and snow-covered conditions from medium-resolution data with a single approach. We applied this method to the multispectral data from the wide-swath Chinese HuanJing (HJ satellites at a spatial resolution of 30 m to demonstrate the feasibility of this data for surface albedo monitoring over rapidly changing surfaces. Validation against ground measurements shows that the method is capable of accurately estimating surface albedo over both snow-free and snow-covered surfaces with an overall root mean square error (RMSE of 0.030 and r-square (R2 of 0.947. The comparison between HJ albedo estimates and the Moderate Resolution Imaging Spectral Radiometer (MODIS albedo product suggests that the HJ data and proposed algorithm can generate robust albedo estimates over various land cover types with an RMSE of 0.011–0.014. The accuracy of HJ albedo estimation improves with the increase in view zenith angles, which further demonstrates the unique advantage of wide-swath satellite data in albedo estimation.

  2. Snow Cover and Vegetation-Induced Decrease in Global Albedo From 2002 to 2016

    Science.gov (United States)

    Li, Qiuping; Ma, Mingguo; Wu, Xiaodan; Yang, Hong

    2018-01-01

    Land surface albedo is an essential parameter in regional and global climate models, and it is markedly influenced by land cover change. Variations in the albedo can affect the surface radiation budget and further impact the global climate. In this study, the interannual variation of albedo from 2002 to 2016 was estimated on the global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) datasets. The presence and causes of the albedo changes for each specific region were also explored. From 2002 to 2016, the MODIS-based albedo decreased globally, snow cover declined by 0.970 (percent per pixel), while the seasonally integrated normalized difference vegetation index increased by 0.175. Some obvious increases in the albedo were detected in Central Asia, northeastern China, parts of the boreal forest in Canada, and the temperate steppe in North America. In contrast, noticeable decreases in the albedo were found in the Siberian tundra, Europe, southeastern Australia, and northeastern regions of North America. In the Northern Hemisphere, the greening trend at high latitudes made more contribution to the decline in the albedo. However, the dramatic fluctuation of snow-cover at midlatitudes predominated in the change of albedo. Our analysis can help to understand the roles that vegetation and snow cover play in the variation of albedo on global and regional scales.

  3. Inclusion of Solar Elevation Angle in Land Surface Albedo Parameterization Over Bare Soil Surface.

    Science.gov (United States)

    Zheng, Zhiyuan; Wei, Zhigang; Wen, Zhiping; Dong, Wenjie; Li, Zhenchao; Wen, Xiaohang; Zhu, Xian; Ji, Dong; Chen, Chen; Yan, Dongdong

    2017-12-01

    Land surface albedo is a significant parameter for maintaining a balance in surface energy. It is also an important parameter of bare soil surface albedo for developing land surface process models that accurately reflect diurnal variation characteristics and the mechanism behind the solar spectral radiation albedo on bare soil surfaces and for understanding the relationships between climate factors and spectral radiation albedo. Using a data set of field observations, we conducted experiments to analyze the variation characteristics of land surface solar spectral radiation and the corresponding albedo over a typical Gobi bare soil underlying surface and to investigate the relationships between the land surface solar spectral radiation albedo, solar elevation angle, and soil moisture. Based on both solar elevation angle and soil moisture measurements simultaneously, we propose a new two-factor parameterization scheme for spectral radiation albedo over bare soil underlying surfaces. The results of numerical simulation experiments show that the new parameterization scheme can more accurately depict the diurnal variation characteristics of bare soil surface albedo than the previous schemes. Solar elevation angle is one of the most important factors for parameterizing bare soil surface albedo and must be considered in the parameterization scheme, especially in arid and semiarid areas with low soil moisture content. This study reveals the characteristics and mechanism of the diurnal variation of bare soil surface solar spectral radiation albedo and is helpful in developing land surface process models, weather models, and climate models.

  4. Design of a Novel Spectral Albedometer for Validating the MODerate Resolution Imaging Spectroradiometer Spectral Albedo Product

    Directory of Open Access Journals (Sweden)

    Hongmin Zhou

    2018-01-01

    Full Text Available Land surface shortwave broadband albedo is a key parameter in general circulation models and surface energy budget models. Multispectral satellite data are typically used to generate broadband albedo products in a three-step process: atmospheric correction, for converting the top-of-atmosphere observations to surface directional reflectance; angular modeling, for converting the surface directional reflectance to spectral albedo of each individual band; and finally, narrowband-to-broadband conversion, for transforming the spectral albedos to broadband albedos. Spectroradiometers can be used for validating surface directional reflectance products and pyranometers or broadband albedometers, for validating broadband albedo products, but spectral albedo products are rarely validated using ground measurements. In this study, we designed a new type of albedometer that can measure spectral albedos. It consists of multiple interference filters and a silicon detector, for measuring irradiance from 400–1100 nm. The linearity of the sensors is 99%, and the designed albedometer exhibits consistency up to 0.993, with a widely-used commercial instrument. A field experiment for measuring spectral albedo of grassland using this new albedometer was conducted in Yudaokou, China and the measurements are used for validating the MODerate Resolution Imaging Spectroradiometer (MODIS spectral albedos. The results show that the biases of the MODIS spectral albedos of the first four bands are −0.0094, 0.0065, 0.0159, and −0.0001, respectively. This new instrument provides an effective technique for validating spectral albedos of any satellite sensor in this spectral range, which is critical for improving satellite broadband albedo products.

  5. Sea Ice, Clouds, Sunlight, and Albedo: The Umbrella Versus the Blanket

    Science.gov (United States)

    Perovich, D. K.

    2017-12-01

    The Arctic sea ice cover has undergone a major decline in recent years, with reductions in ice extent, ice thickness, and ice age. Understanding the feedbacks and forcing driving these changes is critical in improving predictions. The surface radiation budget plays a central role in summer ice melt and is governed by clouds and surface albedo. Clouds act as an umbrella reducing the downwelling shortwave, but also serve as a blanket increasing the downwelling longwave, with the surface albedo also determining the net balance. Using field observations from the SHEBA program, pairs of clear and cloudy days were selected for each month from May through September and the net radiation flux was calculated for different surface conditions and albedos. To explore the impact of albedo we calculated a break even albedo, where the net radiation for cloudy skies is the same as clear skies. For albedos larger than the break-even value the net radiation flux is smaller under clear skies compared to cloudy skies. Break-even albedos ranged from 0.30 in September to 0.58 in July. For snow covered or bare ice, clear skies always resulted in less radiative heat input. In contrast, leads always had, and ponds usually had, more radiative heat input under clear skies than cloudy skies. Snow covered ice had a net radiation flux that was negative or near zero under clear skies resulting in radiative cooling. We combined the albedo of individual ice types with the area of those ice types to calculate albedos averaged over a 50 km x 50 km area. The July case had the smallest areally averaged albedo of 0.50. This was less than the breakeven albedo, so cloudy skies had a smaller net radiation flux than clear skies. For the cases from the other four months, the areally averaged albedo was greater than the break-even albedo. The areally averaged net radiation flux was negative under clear skies for the May and September cases.

  6. Revisiting surface albedo changes over Greenland since 1980s using satellite data from GLASS, CLARA, MODIS, and Landsat

    Science.gov (United States)

    He, T.; Liang, S.; Zhang, Y.

    2017-12-01

    Massive melting events over Greenland have been observed over the past few decades. Accompanying the melting events are the surface albedo changes, which had temporal and spatial variations. Albedo changes over Greenland during the past few decades have been reported in previous studies with the help of satellite observations; however, magnitudes and timing in albedo trends differ greatly in those studies. This has limited our understanding of albedo change mechanisms over Greenland. In this study, we present an analysis of surface albedo change over Greenland since 1980s combining four satellite albedo datasets, namely MODIS, GLASS, CLARA, and Landsat. MODIS, GLASS, and CLARA albedo data are publicly available and Landsat albedos were derived in our earlier study trying to bridge the scale difference between coarse resolution data and ground measurements available from early 1980s. Inter-comparisons were made among the satellite albedos and against ground measurements. We have several new findings. First, trends in surface albedo change among the satellite albedo datasets generally agree with each other and with ground measurements. Second, all datasets showed negative albedo trends after 2000, but magnitudes differ greatly. Third, trends before 2000 from coarse resolution data are not significant but Landsat data observed positive albedo changes. Fourth, the turning point of albedo trend was found to be earlier than 2000. Those findings may bring new research topics on timing and magnitude, and an improved understanding mechanisms of the albedo changes over Greenland during the past few decades.

  7. Competing effects of surface albedo and orographic elevated heating on regional climate

    Science.gov (United States)

    Hu, Shineng; Boos, William R.

    2017-07-01

    All else being equal, a given atmospheric pressure level is thought to be warmer over a plateau than over surrounding nonelevated terrain because of orographic "elevated heating." However, elevated surfaces are also typically brighter due to reduced vegetation and increased ice cover. Here we assess the degree to which surface albedo compensates for orographic elevated heating. We confirm that land surface albedo generally increases with surface elevation in observations. Using a cloud system-resolving model, we show that increased surface albedo strongly compensates for orographic elevated heating in radiative-convective equilibrium. A nonelevated surface with the albedo of modern India would enter a runaway greenhouse regime without ventilation by monsoonal winds, while a surface with the albedo and elevation of Tibet would achieve a cooler radiative-convective equilibrium. Surface albedo changes may thus be just as important as surface elevation changes for the evolution of low-latitude regional climate throughout Earth's history.

  8. Land Surface Albedos Computed from BRF Measurements with a Study of Conversion Formulae

    Directory of Open Access Journals (Sweden)

    Aku Riihelä

    2010-08-01

    Full Text Available Land surface hemispherical albedos of several targets have been resolved using the bidirectional reflectance factor (BRF library of the Finnish Geodetic Institute (FGI. The library contains BRF data measured by FGI during the years 2003–2009. Surface albedos are calculated using selected BRF datasets from the library. Polynomial interpolation and extrapolation have been used in computations. Several broadband conversion formulae generally used for satellite based surface albedo retrieval have been tested. The albedos were typically found to monotonically increase with increasing zenith angle of the Sun. The surface albedo variance was significant even within each target category / surface type. In general, the albedo estimates derived using diverse broadband conversion formulas and estimates obtained by direct integration of the measured spectra were in line.

  9. Using albedo to reform wind erosion modelling, mapping and monitoring

    Science.gov (United States)

    Chappell, Adrian; Webb, Nicholas P.

    2016-12-01

    Wind erosion and dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth's surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and demonstrate that values are an order of magnitude too small and significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted, particularly under sparse surface roughness. We describe a solution which develops published work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas, across platforms from the field to airborne and readily available satellite data. Our new approach demonstrated redundancy in existing wind erosion models and thereby reduced model complexity and improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise fluid dynamics and predict sediment transport without the use of a drag partition scheme (Rt) or threshold friction velocity (u∗t). We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional parameters of wind erosion modelling. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not

  10. Swarm Utilisation Analysis: LEO satellite observations for the ESA's SSA Space Weather network

    Science.gov (United States)

    Kervalishvili, Guram; Stolle, Claudia; Rauberg, Jan; Olsen, Nils; Vennerstrøm, Susanne; Gullikstad Johnsen, Magnar; Hall, Chris

    2017-04-01

    ESA's (European Space Agency) constellation mission Swarm was successfully launched on 22 November 2013. The three satellites achieved their final constellation on 17 April 2014 and since then Swarm-A and Swarm-C orbiting the Earth at about 470 km (flying side-by-side) and Swarm-B at about 520 km altitude. Each of Swarm satellite carries instruments with high precision to measure magnetic and electric fields, neutral and plasma densities, and TEC (Total Electron Content) for which a dual frequency GPS receiver is used. SUA (Swarm Utilisation Analysis) is a project of the ESA's SSA (Space Situational Awareness) SWE (Space Weather) program. Within this framework GFZ (German Research Centre for Geosciences, Potsdam, Germany) and DTU (National Space Institute, Kongens Lyngby, Denmark) have developed two new Swarm products ROT (Rate Of change of TEC) and PEJ (Location and intensity level of Polar Electrojets), respectively. ROT is derived as the first time derivative from the Swarm measurements of TEC at 1 Hz sampling. ROT is highly relevant for users in navigation and communications: strong plasma gradients cause GPS signal degradation or even loss of GPS signal. Also, ROT is a relevant space weather asset irrespective of geomagnetic activity, e.g., high amplitude values of ROT occur during all geomagnetic conditions. PEJ is derived from the Swarm measurements of the magnetic field strength at 1 Hz sampling. PEJ has a high-level importance for power grid companies since the polar electrojet is a major cause for ground-induced currents. ROT and PEJ together with five existing Swarm products TEC, electron density, IBI (Ionospheric Bubble Index), FAC (Field-Aligned Current), and vector magnetic field build the SUA service prototype. This prototype will be integrated into ESA's SSA Space Weather network as a federated service and will be available soon from ESA's SSA SWE Ionospheric Weather and Geomagnetic Conditions Expert Service Centres (ESCs).

  11. Overview of Human-Centric Space Situational Awareness (SSA) Science and Technology (S&T)

    Science.gov (United States)

    Ianni, J.; Aleva, D.; Ellis, S.

    2012-09-01

    A number of organizations, within the government, industry, and academia, are researching ways to help humans understand and react to events in space. The problem is both helped and complicated by the fact that there are numerous data sources that need to be planned (i.e., tasked), collected, processed, analyzed, and disseminated. A large part of the research is in support of the Joint Space Operational Center (JSpOC), National Air and Space Intelligence Center (NASIC), and similar organizations. Much recent research has been specifically targeting the JSpOC Mission System (JMS) which has provided a unifying software architecture. This paper will first outline areas of science and technology (S&T) related to human-centric space situational awareness (SSA) and space command and control (C2) including: 1. Object visualization - especially data fused from disparate sources. Also satellite catalog visualizations that convey the physical relationships between space objects. 2. Data visualization - improve data trend analysis as in visual analytics and interactive visualization; e.g., satellite anomaly trends over time, space weather visualization, dynamic visualizations 3. Workflow support - human-computer interfaces that encapsulate multiple computer services (i.e., algorithms, programs, applications) into a 4. Command and control - e.g., tools that support course of action (COA) development and selection, tasking for satellites and sensors, etc. 5. Collaboration - improve individuals or teams ability to work with others; e.g., video teleconferencing, shared virtual spaces, file sharing, virtual white-boards, chat, and knowledge search. 6. Hardware/facilities - e.g., optimal layouts for operations centers, ergonomic workstations, immersive displays, interaction technologies, and mobile computing. Secondly we will provide a survey of organizations working these areas and suggest where more attention may be needed. Although no detailed master plan exists for human

  12. Potential use of sewage sludge ash (SSA as a cement replacement in precast concrete blocks

    Directory of Open Access Journals (Sweden)

    Pérez-Carrión, M.

    2014-03-01

    Full Text Available The present study explored the technological feasibility of re-using sewage sludge ash (SSA as a Portland cement replacement in commercially manufactured pre cast concrete blocks. The blocks analysed were made to the guidelines laid down in Spain’s National Plan for Waste Water Treatment Plant Sludge, 2001–2006, and European Union specifications (CE marking for such products. Performance was compared in three families of blocks, with 0, 10 and 20% SSA. The findings proved that SSA is apt for pre cast concrete block manufacture and that, in addition to the economic and environmental benefits afforded, its use would improve certain of the properties of conventional block.El objetivo de esta investigación es estudiar el uso potencial de las cenizas de lodos de depuradora (CLD, como sustitución del cemento Portland en bloques de hormigón prefabricados, de forma que se pueda lograr una revalorización de este material de desecho mediante este procedimiento. La metodología utilizada en este trabajo se rige por las directrices del Plan Nacional Español de Lodos de Aguas Residuales de 2001–2006, y por las exigencias del Consejo Europeo (marcado CE, que es obligatorio para este tipo de productos. Se han utilizado dos niveles de sustitución de cemento (10% y 20%, y todos los resultados han sido referidos a las muestras control. Los resultados obtenidos muestran que es posible utilizar una sustitución parcial del cemento por CLD, en la fabricación de bloques de hormigón prefabricados, y por lo tanto, se pueden conseguir beneficios económicos y ambientales, así como la mejora de una serie de propiedades.

  13. Land Surface Albedo Estimation from Chinese HJ Satellite Data Based on the Direct Estimation Approach

    OpenAIRE

    He, Tao; Liang, Shunlin; Wang, Dongdong; Chen, Xiaona; Song, Dan-Xia; Jiang, Bo

    2015-01-01

    Monitoring surface albedo at medium-to-fine resolution (<100 m) has become increasingly important for medium-to-fine scale applications and coarse-resolution data evaluation. This paper presents a method for estimating surface albedo directly using top-of-atmosphere reflectance. This is the first attempt to derive surface albedo for both snow-free and snow-covered conditions from medium-resolution data with a single approach. We applied this method to the multispectral data from the wide-...

  14. Radiative forcing by changes in surface albedo caused by changes in vegetation

    OpenAIRE

    Kvalevåg, Maria Malene

    2005-01-01

    The human influence on vegetation causes changes in the surface reflective properties. By using MODIS land cover and MODIS surface albedo products, an estimation of radiative forcing due to surface albedo changes caused by vegetation changes is performed. A potential natural vegetation data set is used to compute radiative forcing estimates from pre agricultural times to present. A combination between MODIS blacksky and whitesky albedo and diffuse and direct radiation at gr...

  15. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

    Science.gov (United States)

    2015-09-30

    Figure 1). When the ice is snow covered there is little difference in albedo and partitioning between first year and multiyear ice. Once the snow melts...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Sunlight, Sea Ice, and the Ice Albedo Feedback in a...and iv) onset dates of melt and freeze up. 4. Assess the magnitude of the contribution from ice- albedo feedback to the observed decrease of sea ice

  16. Vegetation controls on northern high latitude snow-albedo feedback: Observations and CMIP5 model simulations

    OpenAIRE

    Loranty, MM; Berner, LT; Goetz, SJ; Jin, Y; Randerson, JT

    2014-01-01

    The snow-masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large-scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow-albedo feedback is controlled largely by the contrast between snow-covered and snow-free albedo (Δα), which influences predictions of future warming in coupled climate models, despite being poorly constrained at seasonal and century time scales. Here, ...

  17. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Artic Sea Ice Cover

    Science.gov (United States)

    2015-11-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. SUNLIGHT, SEA ICE , AND THE ICE ALBEDO FEEDBACK IN A...iv) onset dates of melt and freeze up. 4. Assess the magnitude of the contribution from ice - albedo feedback to the observed decrease of sea ice in... sea ice prediction and modeling community to improve the treatment of solar radiation and the ice - albedo feedback. This transfer will take the form of

  18. Albedo, Land Cover, and Daytime Surface Temperature Variation Across an Urbanized Landscape

    Science.gov (United States)

    Trlica, A.; Hutyra, L. R.; Schaaf, C. L.; Erb, A.; Wang, J. A.

    2017-11-01

    Land surface albedo is a key parameter controlling the local energy budget, and altering the albedo of built surfaces has been proposed as a tool to mitigate high near-surface temperatures in the urban heat island. However, most research on albedo in urban landscapes has used coarse-resolution data, and few studies have attempted to relate albedo to other urban land cover characteristics. This study provides an empirical description of urban summertime albedo using 30 m remote sensing measurements in the metropolitan area around Boston, Massachusetts, relating albedo to metrics of impervious cover fraction, tree canopy coverage, population density, and land surface temperature (LST). At 30 m spatial resolution, median albedo over the study area (excluding open water) was 0.152 (0.112-0.187). Trends of lower albedo with increasing urbanization metrics and temperature emerged only after aggregating data to 500 m or the boundaries of individual towns, at which scale a -0.01 change in albedo was associated with a 29 (25-35)% decrease in canopy cover, a 27 (24-30)% increase in impervious cover, and an increase in population from 11 to 386 km-2. The most intensively urbanized towns in the region showed albedo up to 0.035 lower than the least urbanized towns, and mean mid-morning LST 12.6°C higher. Trends in albedo derived from 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) measurements were comparable, but indicated a strong contribution of open water at this coarser resolution. These results reveal linkages between albedo and urban land cover character, and offer empirical context for climate resilient planning and future landscape functional changes with urbanization.

  19. MELiSSA third compartment: Nitrosomonas europaea and Nitrobacter winogradskyi axenic cultures in bioreactors

    Science.gov (United States)

    Cruvellier, Nelly; Lasseur, Christophe; Poughon, Laurent; Creuly, Catherine; Dussap, Gilles

    Nitrogen is a key element for the life and its balance on Earth is regulated by the nitrogen cycle. This loop includes several steps among which nitrification that permits the transformation of the ammonium into nitrate. The MELiSSA loop is an artificial ecosystem designed for life support systems (LSS). It is based on the carbon and nitrogen cycles and the recycling of the non-edible part of the higher plants and the waste produced by the crew. In this order, all the wastes are collected in the first compartment to degrade them into organic acids and CO2. These compounds are joining the second compartment which is a photoheterotrophic compartment where at the outlet an organic-free medium containing ammonium is produced. This solution will be the substrate of the third compartment where nitrification is done. This compartment has to oxidize the ammonium into nitrate, and this biological reaction needs two steps. In the MELiSSA loop, the nitrification is carried out by two bacteria: Nitrosomonas europaea ATCC® 19718™ which is oxidizing ammonia into nitrite and Nitrobacter winogradskyi ATCC® 25391™ which is producing nitrate from nitrite in the third compartment. These two bacteria are growing in axenic conditions on a fixed bed bioreactor filled with Biostyr® beads. The nitrogen compounds are controlled by Ionic Chromatography and colorimetric titration for each sample. The work presented here deals with the culture of both bacteria in pure cultures and mixed cultures in stirred and aerated bioreactors of different volumes. The first aim of our work is the characterization of the bacteria growth in bioreactors and in the nitrifying fixed-bed column. The experimental results confirm that the growth is slow; the maximal growth rate in suspended cultures is 0.054h-1 for Nitrosomonas europaea and 0.022h-1 for Nitrobacter winogradskyi. Mixed cultures are difficult to control and operate but one could be done for more than 500 hours. The characterization of the

  20. The albedo of martian dunes: Insights into aeolian activity and dust devil formation

    Science.gov (United States)

    Bennett, K. A.; Fenton, L.; Bell, J. F.

    2017-06-01

    Wind is the primary geologic process currently active on the surface of Mars. Albedo variations at eight dune fields were tested based on the hypothesis that a dune's ripple migration rate is correlated to its albedo. On Mars, where the atmospheric pressure is low, dust is removed from the surface of a dune by saltating sand. Therefore, more active dunes should remove dust more efficiently than less active dunes. A dune's albedo was found to be low in the first half of the Mars year (Ls = 0-180°) and high in the second half (Ls = 180-360°) during the dusty season. Both dunes with fast- and slow-moving ripples exhibit low albedos, whereas dunes with ripples that migrate at intermediate speeds exhibit high albedos. A dune's minimum albedo does not have a simple correlation with its ripple migration rate. Instead, we propose that dust devils remove dust on slow-moving and immobile dunes, whereas saltating sand caused by strong winds removes dust on faster dunes. Albedo should not be used as a proxy for migration rate of ripples or dune activity, as it may be difficult to distinguish between fast- and slow-moving ripples on dunes that have the same albedo. The presence of dust devil tracks on a dune could indicate the dune and/or its ripples are either immobile or migrating slowly. We also propose that albedo variations on individual dune fields can reveal insight into the local wind regime.

  1. The accuracy of satellite-derived albedo for northern alpine and glaciated land covers

    Science.gov (United States)

    Williamson, Scott N.; Copland, Luke; Hik, David S.

    2016-09-01

    Alpine and Arctic land cover can present a challenge for the validation of satellite-derived albedo measurements due, in part, to the complex terrain and logistical difficulty of accessing these regions. We compared measurements of albedo on transects from northern mountain land covers (snowfield, glacier ice, tundra, saline silt river delta) and over a large elevation range to the coincident 8-day MODIS (MCD43) albedo product. We also compared field measurements at snow covered sites to the coincident daily MODIS (MOD10A1) snow albedo product. For each transect, we measured a range of albedo values, with the least variability on the silt river delta (range = 0.084) and the largest over mid-elevation glacier ice (range = 0.307). The highest elevation snowfield (0.170) had nearly the same range of albedo values as tundra (0.164). The MODIS shortwave White Sky Albedo product (MCD43A3) was highly correlated with the field transect albedo (R2 = 0.96), with a Root Mean Square Error (RMSE) of 0.061. The MODIS shortwave Black Sky Albedo product was similarly correlated with field transects (R2 = 0.96; RMSE = 0.063). These results indicate that remote observation of albedo over snow covered and alpine terrain is well constrained and consistent with other studies. Albedo varied by ∼15% both spatially and temporally for the high elevation snowfields at the point in the season where albedo variation should be at its minimum. There were several instances where MCD43A3 albedo was not produced over snow and was instead classified as cloud covered, despite field observations of cloud free skies. There were also several instances where daily MOD10A1 albedo was produced during the coincident 8-day period at these locations. This suggests that the cloud mask in the MCD43 product is overly conservative over snow. Spatial variation in albedo within the MODIS grid cell (500 m), especially for snow and glacier ice, combined with the uncertainty associated with positional accuracy of

  2. MODIS/Terra+Aqua Albedo 16-Day L3 Global 500m SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODerate-resolution Imaging Spectroradiometer (MODIS) Albedo product (MCD43A3) provides 500-meter data describing both directional hemispherical reflectance...

  3. Vegetation controls on northern high latitude snow-albedo feedback: observations and CMIP5 model simulations.

    Science.gov (United States)

    Loranty, Michael M; Berner, Logan T; Goetz, Scott J; Jin, Yufang; Randerson, James T

    2014-02-01

    The snow-masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large-scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow-albedo feedback is controlled largely by the contrast between snow-covered and snow-free albedo (Δα), which influences predictions of future warming in coupled climate models, despite being poorly constrained at seasonal and century time scales. Here, we compare satellite observations and coupled climate model representations of albedo and tree cover for the boreal and Arctic region. Our analyses reveal consistent declines in albedo with increasing tree cover, occurring south of latitudinal tree line, that are poorly represented in coupled climate models. Observed relationships between albedo and tree cover differ substantially between snow-covered and snow-free periods, and among plant functional type. Tree cover in models varies widely but surprisingly does not correlate well with model albedo. Furthermore, our results demonstrate a relationship between tree cover and snow-albedo feedback that may be used to accurately constrain high latitude albedo feedbacks in coupled climate models under current and future vegetation distributions. © 2013 John Wiley & Sons Ltd.

  4. Analysis on variability and trend in Antarctic sea ice albedo between 1983 and 2009

    Science.gov (United States)

    Seo, Minji; Kim, Hyun-cheol; Choi, Sungwon; Lee, Kyeong-sang; Han, Kyung-soo

    2017-04-01

    Sea ice is key parameter in order to understand the cryosphere climate change. Several studies indicate the different trend of sea ice between Antarctica and Arctic. Albedo is important factor for understanding the energy budget and factors for observing of environment changes of Cryosphere such as South Pole, due to it mainly covered by ice and snow with high albedo value. In this study, we analyzed variability and trend of long-term sea ice albedo data to understand the changes of sea ice over Antarctica. In addiction, sea ice albedo researched the relationship with Antarctic oscillation in order to determine the atmospheric influence. We used the sea ice albedo data at The Satellite Application Facility on Climate Monitoring and Antarctic Oscillation data at NOAA Climate Prediction Center (CPC). We analyzed the annual trend in albedo using linear regression to understand the spatial and temporal tendency. Antarctic sea ice albedo has two spatial trend. Weddle sea / Ross sea sections represent a positive trend (0.26% ˜ 0.04% yr-1) and Bellingshausen Amundsen sea represents a negative trend (- 0.14 ˜ -0.25%yr-1). Moreover, we performed the correlation analysis between albedo and Antarctic oscillation. As a results, negative area indicate correlation coefficient of - 0.3639 and positive area indicates correlation coefficient of - 0.0741. Theses results sea ice albedo has regional trend according to ocean. Decreasing sea ice trend has negative relationship with Antarctic oscillation, its represent a possibility that sea ice influence atmospheric factor.

  5. The seasonal cycle of snow cover, sea ice and surface albedo

    Science.gov (United States)

    Robock, A.

    1980-01-01

    The paper examines satellite data used to construct mean snow cover caps for the Northern Hemisphere. The zonally averaged snow cover from these maps is used to calculate the seasonal cycle of zonally averaged surface albedo. The effects of meltwater on the surface, solar zenith angle, and cloudiness are parameterized and included in the calculations of snow and ice albedo. The data allows a calculation of surface albedo for any land or ocean 10 deg latitude band as a function of surface temperature ice and snow cover; the correct determination of the ice boundary is more important than the snow boundary for accurately simulating the ice and snow albedo feedback.

  6. The Importance of Snow Albedo for Ice Sheet Evolution over the Last Glacial Cycle

    Science.gov (United States)

    Ganopolski, A.; Willeit, M.

    2017-12-01

    The surface energy and mass balance of ice sheets strongly depends on the amount of solar radiation absorbed at the surface, which is mainly controlled by the albedo of snow and ice. Here, using an Earth system model of intermediate complexity, we explore the role played by surface albedo for the simulation of glacial cycles. We show that the evolution of the Northern Hemisphere ice sheets over the last glacial cycle is very sensitive to the representation of snow albedo in the model. It is well known that the albedo of snow depends strongly on the snow grain size and the content of light absorbing impurities. Excluding either the snow aging effect or the dust darkening effect on snow albedo leads to an excessive ice build-up during glacial times and consequently to a failure in simulating deglaciation. While the effect of snow grain growth on snow albedo is well constrained, the albedo reduction due to the presence of dust in snow is much more uncertain, because the light absorbing properties of dust vary widely as a function of dust composition. We also show that assuming slightly different optical properties of dust leads to very different ice sheet and climate evolutions in the model. Conversely, ice sheet evolution is less sensitive to the choice of ice albedo in the model. We conclude that a proper representation of snow albedo is a fundamental prerequisite for a successful simulation of glacial cycles.

  7. A Tailorable Structural Composite for GCR and Albedo Neutron Protection on the Lunar Surface, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A tailorable structural composite that will provide protection from the lunar radiation environment, including GCR and albedo neutrons will be developed. This...

  8. Assessment of NPP VIIRS Albedo Over Heterogeneous Crop Land in Northern China

    Science.gov (United States)

    Wu, Xiaodan; Wen, Jianguang; Xiao, Qing; Yu, Yunyue; You, Dongqin; Hueni, Andreas

    2017-12-01

    In this paper, the accuracy of Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (VIIRS) land surface albedo, which is derived from the direct estimation algorithm, was assessed using ground-based albedo observations from a wireless sensor network over a heterogeneous cropland in the Huailai station, northern China. Data from six nodes spanning 2013-2014 over vegetation, bare soil, and mixed terrain surfaces were utilized to provide ground reference at VIIRS pixel scale. The performance of VIIRS albedo was also compared with Global LAnd Surface Satellite (GLASS) and Moderate Resolution Imaging Spectroradiometer (MODIS) albedos (Collection 5 and 6). The results indicate that the current granular VIIRS albedo has a high accuracy with a root-mean-square error of 0.02 for typical land covers. They are significantly correlated with ground references indicated by a correlation coefficient (R) of 0.73. The VIIRS albedo shows distinct advantages to GLASS and MODIS albedos over bare soil and mixed-cover surfaces, while it is inferior to the other two products over vegetated surfaces. Furthermore, its time continuity and the ability to capture the abrupt change of surface albedo are better than that of GLASS and MODIS albedo.

  9. Mars - Experimental study of albedo changes caused by dust fallout

    Science.gov (United States)

    Wells, E. N.; Veverka, J.; Thomas, P.

    1984-01-01

    A laboratory apparatus was used to simulate the uniform fallout and deposition of particles 1 to 5 microns in diameter in an experimental study on how the spectral and photometric properties of representative Martian areas are affected by fallout of atmospheric dust (smaller than or equalling 60 microns) suspended during dust storms. In this study, measurements are made in the changes in reflectance at optical and near-infrared wavelengths (0.4 to 1.2 micron) caused by deposition of varying amounts of a Mars-analog dust on bright and dark substrates before and after deposition of 6 x 10 to the -5th to 1.5 x 10 to the -3rd g/sq cm of simulated fallout. It is believed that only small amounts of dust particles (approximately 3 x 10 to the -4th g/sq cm) are needed to make significant albedo changes in dark areas of Mars, and that this would rule out uniform dust deposition on the surface of the planet. Data also indicate that other high albedo features like bright crater-related wind streaks may not be areas of significant sediment deposits. Laboratory simulations have permitted estimates of how much the reflectance of an area on Mars would change given a certain amount of dust fallout (g/sq cm) or reflectance data. These simulations may also be useful in tracking the transport and deposition of the dust.

  10. Tackling regional climate change by leaf albedo bio-geoengineering.

    Science.gov (United States)

    Ridgwell, Andy; Singarayer, Joy S; Hetherington, Alistair M; Valdes, Paul J

    2009-01-27

    The likelihood that continuing greenhouse-gas emissions will lead to an unmanageable degree of climate change has stimulated the search for planetary-scale technological solutions for reducing global warming ("geoengineering"), typically characterized by the necessity for costly new infrastructures and industries. We suggest that the existing global infrastructure associated with arable agriculture can help, given that crop plants exert an important influence over the climatic energy budget because of differences in their albedo (solar reflectivity) compared to soils and to natural vegetation. Specifically, we propose a "bio-geoengineering" approach to mitigate surface warming, in which crop varieties having specific leaf glossiness and/or canopy morphological traits are specifically chosen to maximize solar reflectivity. We quantify this by modifying the canopy albedo of vegetation in prescribed cropland areas in a global-climate model, and thereby estimate the near-term potential for bio-geoengineering to be a summertime cooling of more than 1 degrees C throughout much of central North America and midlatitude Eurasia, equivalent to seasonally offsetting approximately one-fifth of regional warming due to doubling of atmospheric CO(2). Ultimately, genetic modification of plant leaf waxes or canopy structure could achieve greater temperature reductions, although better characterization of existing intraspecies variability is needed first.

  11. A Multi-Scale Validation Strategy for Albedo Products over Rugged Terrain and Preliminary Application in Heihe River Basin, China

    Directory of Open Access Journals (Sweden)

    Xingwen Lin

    2018-01-01

    Full Text Available The issue for the validation of land surface remote sensing albedo products over rugged terrain is the scale effects between the reference albedo measurements and coarse scale albedo products, which is caused by the complex topography. This paper illustrates a multi-scale validation strategy specified for coarse scale albedo validation over rugged terrain. A Mountain-Radiation-Transfer-based (MRT-based albedo upscaling model was proposed in the process of multi-scale validation strategy for aggregating fine scale albedo to coarse scale. The simulated data of both the reference coarse scale albedo and fine scale albedo were used to assess the performance and uncertainties of the MRT-based albedo upscaling model. The results showed that the MRT-based model could reflect the albedo scale effects over rugged terrain and provided a robust solution for albedo upscaling from fine scale to coarse scale with different mean slopes and different solar zenith angles. The upscaled coarse scale albedos had the great agreements with the simulated coarse scale albedo with a Root-Mean-Square-Error (RMSE of 0.0029 and 0.0017 for black sky albedo (BSA and white sky albedo (WSA, respectively. Then the MRT-based model was preliminarily applied for the assessment of daily MODerate Resolution Imaging Spectroradiometer (MODIS Albedo Collection V006 products (MCD43A3 C6 over rugged terrain. Results showed that the MRT-based model was effective and suitable for conducting the validation of MODIS albedo products over rugged terrain. In this research area, it was shown that the MCD43A3 C6 products with full inversion algorithm, were generally in agreement with the aggregated coarse scale reference albedos over rugged terrain in the Heihe River Basin, with the BSA RMSE of 0.0305 and WSA RMSE of 0.0321, respectively, which were slightly higher than those over flat terrain.

  12. Spatial correlation between submillimetre and Lyman-alpha galaxies in the SSA 22 protocluster.

    Science.gov (United States)

    Tamura, Yoichi; Kohno, Kotaro; Nakanishi, Kouichiro; Hatsukade, Bunyo; Iono, Daisuke; Wilson, Grant W; Yun, Min S; Takata, Tadafumi; Matsuda, Yuichi; Tosaki, Tomoka; Ezawa, Hajime; Perera, Thushara A; Scott, Kimberly S; Austermann, Jason E; Hughes, David H; Aretxaga, Itziar; Chung, Aeree; Oshima, Tai; Yamaguchi, Nobuyuki; Tanaka, Kunihiko; Kawabe, Ryohei

    2009-05-07

    Lyman-alpha emitters are thought to be young, low-mass galaxies with ages of approximately 10(8) yr (refs 1, 2). An overdensity of them in one region of the sky (the SSA 22 field) traces out a filamentary structure in the early Universe at a redshift of z approximately 3.1 (equivalent to 15 per cent of the age of the Universe) and is believed to mark a forming protocluster. Galaxies that are bright at (sub)millimetre wavelengths are undergoing violent episodes of star formation, and there is evidence that they are preferentially associated with high-redshift radio galaxies, so the question of whether they are also associated with the most significant large-scale structure growing at high redshift (as outlined by Lyman-alpha emitters) naturally arises. Here we report an imaging survey of 1,100-microm emission in the SSA 22 region. We find an enhancement of submillimetre galaxies near the core of the protocluster, and a large-scale correlation between the submillimetre galaxies and the low-mass Lyman-alpha emitters, suggesting synchronous formation of the two very different types of star-forming galaxy within the same structure at high redshift. These results are in general agreement with our understanding of the formation of cosmic structure.

  13. BOREAS TE-1 CO2 and CH4 Flux Data Over the SSA-OBS Site

    Science.gov (United States)

    Anderson, Darwin; Papagno, Andrea; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor)

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall transect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains carbon dioxide and methane flux values from the SSA-OBS site. The data were collected from 09-Jun to 04-Sep-1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  14. BOREAS TE-1 CH4 Flux Data Over The SSA-OA

    Science.gov (United States)

    Anderson, Darwin; Papagno, Andrea; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor)

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall transect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains methane flux and soil profile methane concentration values from the SSA-OA site. The data were collected from 29-May to 17-Sep-1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  15. Linking glacier annual mass balance and glacier albedo retrieved from MODIS data

    Directory of Open Access Journals (Sweden)

    M. Dumont

    2012-12-01

    Full Text Available Albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODerate Imaging Spectroradiometer (MODIS on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ice are particularly investigated. The methods are tested on the Saint Sorlin Glacier (Grandes Rousses area, French Alps. The accuracy of the retrieved albedo is estimated using both field measurements, at two automatic weather stations located on the glacier, and albedo values derived from terrestrial photographs. For summers 2008 and 2009, the root mean square deviation (RMSD between field measurements and the broadband albedo retrieved from MODIS data at 250 m spatial resolution was found to be 0.052 or about 10% relative error. The RMSD estimated for the MOD10 daily albedo product is about three times higher. One decade (2000–2009 of MODIS data were then processed to create a time series of albedo maps of Saint Sorlin Glacier during the ablation season. The annual mass balance of Saint Sorlin Glacier was compared with the minimum albedo value (average over the whole glacier surface observed with MODIS during the ablation season. A strong linear correlation exists between the two variables. Furthermore, the date when the average albedo of the whole glacier reaches a minimum closely corresponds to the period when the snow line is located at its highest elevation, thus when the snow line is a good indicator of the glacier equilibrium line. This indicates that this strong correlation results from the fact that the minimal average albedo values of the glacier contains considerable information regarding the relative share of areal surfaces between the ablation zone (i.e. ice with generally

  16. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations.

    Science.gov (United States)

    Wang, Tao; Peng, Shushi; Krinner, Gerhard; Ryder, James; Li, Yue; Dantec-Nédélec, Sarah; Ottlé, Catherine

    2015-01-01

    Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation) into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique) improve the simulation accuracy of mean seasonal (October throughout May) snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the magnitude of

  17. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations.

    Directory of Open Access Journals (Sweden)

    Tao Wang

    Full Text Available Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique improve the simulation accuracy of mean seasonal (October throughout May snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the

  18. Spatio-temporal Variability of Albedo and its Impact on Glacier Melt Modelling

    Science.gov (United States)

    Kinnard, C.; Mendoza, C.; Abermann, J.; Petlicki, M.; MacDonell, S.; Urrutia, R.

    2017-12-01

    Albedo is an important variable for the surface energy balance of glaciers, yet its representation within distributed glacier mass-balance models is often greatly simplified. Here we study the spatio-temporal evolution of albedo on Glacier Universidad, central Chile (34°S, 70°W), using time-lapse terrestrial photography, and investigate its effect on the shortwave radiation balance and modelled melt rates. A 12 megapixel digital single-lens reflex camera was setup overlooking the glacier and programmed to take three daily images of the glacier during a two-year period (2012-2014). One image was chosen for each day with no cloud shading on the glacier. The RAW images were projected onto a 10m resolution digital elevation model (DEM), using the IMGRAFT software (Messerli and Grinsted, 2015). A six-parameter camera model was calibrated using a single image and a set of 17 ground control points (GCPs), yielding a georeferencing accuracy of accounting for possible camera movement over time. The reflectance values from the projected image were corrected for topographic and atmospheric influences using a parametric solar irradiation model, following a modified algorithm based on Corripio (2004), and then converted to albedo using reference albedo measurements from an on-glacier automatic weather station (AWS). The image-based albedo was found to compare well with independent albedo observations from a second AWS in the glacier accumulation area. Analysis of the albedo maps showed that the albedo is more spatially-variable than the incoming solar radiation, making albedo a more important factor of energy balance spatial variability. The incorporation of albedo maps within an enhanced temperature index melt model revealed that the spatio-temporal variability of albedo is an important factor for the calculation of glacier-wide meltwater fluxes.

  19. Simulation and Analysis of Topographic Effect on Land Surface Albedo over Mountainous Areas

    Science.gov (United States)

    Hao, D.; Wen, J.; Xiao, Q.

    2017-12-01

    Land surface albedo is one of the significant geophysical variables affecting the Earth's climate and controlling the surface radiation budget. Topography leads to the formation of shadows and the redistribution of incident radiation, which complicates the modeling and estimation of the land surface albedo. Some studies show that neglecting the topography effect may lead to significant bias in estimating the land surface albedo for the sloping terrain. However, for the composite sloping terrain, the topographic effects on the albedo remain unclear. Accurately estimating the sub-topographic effect on the land surface albedo over the composite sloping terrain presents a challenge for remote sensing modeling and applications. In our study, we focus on the development of a simplified estimation method for land surface albedo including black-sky albedo (BSA) and white-sky albedo (WSA) of the composite sloping terrain at a kilometer scale based on the fine scale DEM (30m) and quantitatively investigate and understand the topographic effects on the albedo. The albedo is affected by various factors such as solar zenith angle (SZA), solar azimuth angle (SAA), shadows, terrain occlusion, and slope and aspect distribution of the micro-slopes. When SZA is 30°, the absolute and relative deviations between the BSA of flat terrain and that of rugged terrain reaches 0.12 and 50%, respectively. When the mean slope of the terrain is 30.63° and SZA=30°, the absolute deviation of BSA caused by SAA can reach 0.04. The maximal relative and relative deviation between the WSA of flat terrain and that of rugged terrain reaches 0.08 and 50%. These results demonstrate that the topographic effect has to be taken into account in the albedo estimation.

  20. Monitoring land surface albedo and vegetation dynamics using high spatial and temporal resolution synthetic time series from Landsat and the MODIS BRDF/NBAR/albedo product

    Science.gov (United States)

    Wang, Zhuosen; Schaaf, Crystal B.; Sun, Qingsong; Kim, JiHyun; Erb, Angela M.; Gao, Feng; Román, Miguel O.; Yang, Yun; Petroy, Shelley; Taylor, Jeffrey R.; Masek, Jeffrey G.; Morisette, Jeffrey T.; Zhang, Xiaoyang; Papuga, Shirley A.

    2017-07-01

    Seasonal vegetation phenology can significantly alter surface albedo which in turn affects the global energy balance and the albedo warming/cooling feedbacks that impact climate change. To monitor and quantify the surface dynamics of heterogeneous landscapes, high temporal and spatial resolution synthetic time series of albedo and the enhanced vegetation index (EVI) were generated from the 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) operational Collection V006 daily BRDF/NBAR/albedo products and 30 m Landsat 5 albedo and near-nadir reflectance data through the use of the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). The traditional Landsat Albedo (Shuai et al., 2011) makes use of the MODIS BRDF/Albedo products (MCD43) by assigning appropriate BRDFs from coincident MODIS products to each Landsat image to generate a 30 m Landsat albedo product for that acquisition date. The available cloud free Landsat 5 albedos (due to clouds, generated every 16 days at best) were used in conjunction with the daily MODIS albedos to determine the appropriate 30 m albedos for the intervening daily time steps in this study. These enhanced daily 30 m spatial resolution synthetic time series were then used to track albedo and vegetation phenology dynamics over three Ameriflux tower sites (Harvard Forest in 2007, Santa Rita in 2011 and Walker Branch in 2005). These Ameriflux sites were chosen as they are all quite nearby new towers coming on line for the National Ecological Observatory Network (NEON), and thus represent locations which will be served by spatially paired albedo measures in the near future. The availability of data from the NEON towers will greatly expand the sources of tower albedometer data available for evaluation of satellite products. At these three Ameriflux tower sites the synthetic time series of broadband shortwave albedos were evaluated using the tower albedo measurements with a Root Mean Square Error (RMSE) less than 0.013 and a

  1. An Investigation of Ice Surface Albedo and Its Influence on the High-Altitude Lakes of the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Jiahe Lang

    2018-02-01

    Full Text Available Most high-altitude lakes are more sensitive to global warming than the regional atmosphere. However, most existing climate models produce unrealistic surface temperatures on the Tibetan Plateau (TP lakes, and few studies have focused on the influence of ice surface albedo on high-altitude lakes. Based on field albedo measurements, moderate resolution imaging spectrometer (MODIS albedo products and numerical simulation, this study evaluates the ice albedo parameterization schemes in existing lake models and investigates the characteristics of the ice surface albedo in six typical TP lakes, as well as the influence of ice albedo error in the FLake model. Compared with observations, several ice albedo schemes all clearly overestimate the lake ice albedo by 0.26 to 0.66, while the average bias of MODIS albedo products is only 0.07. The MODIS-observed albedo of a snow-covered lake varies with the snow proportion, and the lake surface albedo in a snow-free state is approximately 0.15 during the frozen period. The MODIS-observed ice surface (snow-free albedos are concentrated within the ranges of 0.14–0.16, 0.08–0.10 and 0.10–0.12 in Aksai Chin Lake, Nam Co Lake and Ngoring Lake, respectively. The simulated lake surface temperature is sensitive to variations in lake ice albedo especially in the spring and winter.

  2. ExploreNEOs: Average albedo by taxonomic complex in the near-Earth asteroid population

    NARCIS (Netherlands)

    Thomas, C. A.; Trilling, D. E.; Emery, J. P.; Mueller, M.; Hora, J. L.; Benner, L. A. M.; Bhattacharya, B.; Bottke, W. F.; Chesley, S.; Delbo, M.; Fazio, G.; Harris, A. W.; Mainzer, A.; Mommert, M.; Morbidelli, A.; Penprase, B.; Smith, H. A.; Spahr, T. B.; Stansberry, J. A.

    2011-01-01

    Understanding the albedo distribution of the Near- Earth Object (NEO) population allows for a better understanding of the relationship between absolute magnitude and size, which impacts calculations of size frequency distribution and impact hazards. Examining NEO albedos also sheds light on the

  3. ALBEDO MODELS FOR SNOW AND ICE ON A FRESHWATER LAKE. (R824801)

    Science.gov (United States)

    AbstractSnow and ice albedo measurements were taken over a freshwater lake in Minnesota for three months during the winter of 1996¯1997 for use in a winter lake water quality model. The mean albedo of new snow was measured as 0.83±0.028, while the...

  4. Global analysis of radiative forcing from fire-induced shortwave albedo change

    NARCIS (Netherlands)

    López-Saldaña, G.; Bistinas, I.; Pereira, J. M.C.

    2015-01-01

    Land surface albedo, a key parameter to derive Earth's surface energy balance, is used in the parameterization of numerical weather prediction, climate monitoring and climate change impact assessments. Changes in albedo due to fire have not been fully investigated on a continental and global scale.

  5. Assimilation of satellite observed snow albedo in a land surface model

    NARCIS (Netherlands)

    Malik, M.J.; van der Velde, R.; Vekerdy, Z.; Su, Zhongbo

    2012-01-01

    This study assesses the impact of assimilating satellite-observed snow albedo on the Noah land surface model (LSM)-simulated fluxes and snow properties. A direct insertion technique is developed to assimilate snow albedo into Noah and is applied to three intensive study areas in North Park

  6. Dominance of grain size impacts on seasonal snow albedo at open sites in New Hampshire

    Science.gov (United States)

    Adolph, Alden C.; Albert, Mary R.; Lazarcik, James; Dibb, Jack E.; Amante, Jacqueline M.; Price, Andrea

    2017-01-01

    Snow cover serves as a major control on the surface energy budget in temperate regions due to its high reflectivity compared to underlying surfaces. Winter in the northeastern United States has changed over the last several decades, resulting in shallower snowpacks, fewer days of snow cover, and increasing precipitation falling as rain in the winter. As these climatic changes occur, it is imperative that we understand current controls on the evolution of seasonal snow albedo in the region. Over three winter seasons between 2013 and 2015, snow characterization measurements were made at three open sites across New Hampshire. These near-daily measurements include spectral albedo, snow optical grain size determined through contact spectroscopy, snow depth, snow density, black carbon content, local meteorological parameters, and analysis of storm trajectories using the Hybrid Single-Particle Lagrangian Integrated Trajectory model. Using analysis of variance, we determine that land-based winter storms result in marginally higher albedo than coastal storms or storms from the Atlantic Ocean. Through multiple regression analysis, we determine that snow grain size is significantly more important in albedo reduction than black carbon content or snow density. And finally, we present a parameterization of albedo based on days since snowfall and temperature that accounts for 52% of variance in albedo over all three sites and years. Our improved understanding of current controls on snow albedo in the region will allow for better assessment of potential response of seasonal snow albedo and snow cover to changing climate.

  7. Growing season carries stronger contributions to albedo dynamics on the Tibetan plateau.

    Science.gov (United States)

    Tian, Li; Chen, Jiquan; Zhang, Yangjian

    2017-01-01

    The Tibetan Plateau has experienced higher-than-global-average climate warming in recent decades, resulting in many significant changes in ecosystem structure and function. Among them is albedo, which bridges the causes and consequences of land surface processes and climate. The plateau is covered by snow/ice and vegetation in the non-growing season (nGS) and growing season (GS), respectively. Based on the MODIS products, we investigated snow/ice cover and vegetation greenness in relation to the spatiotemporal changes of albedo on the Tibetan Plateau from 2000 through 2013. A synchronous relationship was found between the change in GSNDVI and GSalbedo over time and across the Tibetan landscapes. We found that the annual average albedo had a decreasing trend, but that the albedo had slightly increased during the nGS and decreased during the GS. Across the landscapes, the nGSalbedo fluctuated in a synchronous pattern with snow/ice cover. Temporally, monthly snow/ice coverage also had a high correspondence with albedo, except in April and October. We detected clear dependencies of albedo on elevation. With the rise in altitude, the nGSalbedo decreased below 4000 m, but increased for elevations of 4500-5500 m. Above 5500 m, the nGSalbedo decreased, which was in accordance with the decreased amount of snow/ice coverage and the increased soil moisture on the plateau. More importantly, the decreasing albedo in the most recent decade appeared to be caused primarily by lowered growing season albedo.

  8. Variation in foliar nitrogen and albedo in response to nitrogen fertilization and elevated CO2

    Science.gov (United States)

    Haley F. Wicklein; Scott V. Ollinger; Mary E. Martin; David Y. Hollinger; Lucie C. Lepine; Michelle C. Day; Megan K. Bartlett; Andrew D. Richardson; Richard J. Norby

    2012-01-01

    Foliar nitrogen has been shown to be positively correlated with midsummer canopy albedo and canopy near infrared (NIR) reflectance over a broad range of plant functional types (e.g., forests, grasslands, and agricultural lands). To date, the mechanism(s) driving the nitrogen-albedo relationship have not been established, and it is unknown whether factors affecting...

  9. Reconciling Space Object Observed and Solar Pressure Albedo-Areas Via Astrometric and Photometric Data Fusion

    Science.gov (United States)

    Jah, M.; Mallik, V.

    There are many Resident Space Objects (RSOs) in the Geostationary Earth Orbit (GEO) regime, both operational and debris. The primary non-gravitational force acting on these RSOs is Solar Radiation Pressure (SRP), which is sensitive to the RSO’s area-to-mass ratio. Sparse observation data and mismodelling of non-gravitational forces has constrained the state of practice in tracking and characterizing RSOs. Accurate identification, characterization, tracking, and motion prediction of RSOs is a high priority research issue as it shall aid in assessing collision probabilities in the GEO regime, and orbital safety writ large. Previous work in characterizing RSOs has taken a preliminary step in exploiting fused astrometric and photometric data to estimate the RSO mass, shape, attitude, and size. This works, in theory, since angles data are sensitive to SRP albedo-area-to-mass ratio, and photometric data are sensitive to shape, attitude, and observed albedo-area. By fusing these two data types, mass and albedo-area both become observable parameters and can be estimated as independent quantities. However, previous work in mass and albedo-area estimation has not quantified and assessed the fundamental physical link between SRP albedo-area and observed albedo-area. The observed albedo-area is always a function of the SRP albedo-area along the line of sight of the observer. This is the physical relationship that this current research exploits.

  10. A new albedo parameterization for use in climate models over the Antarctic ice sheet

    NARCIS (Netherlands)

    Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Flanner, M.G.; Gardner, A.S.; van de Berg, W.J.|info:eu-repo/dai/nl/304831611

    2011-01-01

    A parameterization for broadband snow surface albedo, based on snow grain size evolution, cloud optical thickness, and solar zenith angle, is implemented into a regional climate model for Antarctica and validated against field observations of albedo for the period 1995–2004. Over the Antarctic

  11. A Cloud-based, Open-Source, Command-and-Control Software Paradigm for Space Situational Awareness (SSA)

    Science.gov (United States)

    Melton, R.; Thomas, J.

    With the rapid growth in the number of space actors, there has been a marked increase in the complexity and diversity of software systems utilized to support SSA target tracking, indication, warning, and collision avoidance. Historically, most SSA software has been constructed with "closed" proprietary code, which limits interoperability, inhibits the code transparency that some SSA customers need to develop domain expertise, and prevents the rapid injection of innovative concepts into these systems. Open-source aerospace software, a rapidly emerging, alternative trend in code development, is based on open collaboration, which has the potential to bring greater transparency, interoperability, flexibility, and reduced development costs. Open-source software is easily adaptable, geared to rapidly changing mission needs, and can generally be delivered at lower costs to meet mission requirements. This paper outlines Ball's COSMOS C2 system, a fully open-source, web-enabled, command-and-control software architecture which provides several unique capabilities to move the current legacy SSA software paradigm to an open source model that effectively enables pre- and post-launch asset command and control. Among the unique characteristics of COSMOS is the ease with which it can integrate with diverse hardware. This characteristic enables COSMOS to serve as the command-and-control platform for the full life-cycle development of SSA assets, from board test, to box test, to system integration and test, to on-orbit operations. The use of a modern scripting language, Ruby, also permits automated procedures to provide highly complex decision making for the tasking of SSA assets based on both telemetry data and data received from outside sources. Detailed logging enables quick anomaly detection and resolution. Integrated real-time and offline data graphing renders the visualization of the both ground and on-orbit assets simple and straightforward.

  12. The influence of inter-annually varying albedo on regional climate and drought

    KAUST Repository

    Meng, Xianhong

    2013-05-05

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  13. Albedo Spatial Variability and Causes on the Western Greenland Ice Sheet Percolation Zone

    Science.gov (United States)

    Lewis, G.; Osterberg, E. C.; Hawley, R. L.; Koffman, B. G.; Marshall, H. P.; Birkel, S. D.; Dibb, J. E.

    2016-12-01

    Many recent studies have concluded that Greenland Ice Sheet (GIS) mass loss has been accelerating over recent decades, but spatial and temporal variations in GIS mass balance remain poorly understood due to a complex relationship among precipitation and temperature changes, increasing melt and runoff, ice discharge, and surface albedo. Satellite measurements from MODerate resolution Imaging Spectroradiometer (MODIS) indicate that albedo has been declining over the past decade, but the cause and extent of GIS albedo change remains poorly constrained by field data. As fresh snow (albedo > 0.85) warms and melts, its albedo decreases due to snow grain growth, promoting solar absorption, higher snowpack temperatures and further melt. However, dark impurities like soot and dust can also significantly reduce snow albedo, even in the dry snow zone. While many regional climate models (e.g. the Regional Atmospheric Climate MOdel - RACMO2) calculate albedo spatial resolutions on the order of 10-30 km, and MODIS averages albedo over 500 m, surface features like sastrugi can affect albedo on much smaller scales. Here we assess the relative importance of grain size and shape vs. impurity concentrations on albedo in the western GIS percolation zone. We collected broadband albedo measurements (300-2500 nm at 3-8 nm resolution) at 35 locations using an ASD FieldSpec4 spectroradiometer to simultaneously quantify radiative fluxes and spectral reflectance. Measurements were collected on 10 x 10 m, 1 x 1 km, 5 x 5 km, and 10 x 10 km grids to determine the spatial variability of albedo as part of the 850-km Greenland Traverse for Accumulation and Climate Studies (GreenTrACS) traverse from Raven/Dye 2 to Summit. Additionally, we collected shallow (0-50 cm) snow pit samples every 5 cm at ASD measurement sites to quantify black carbon and mineral dust concentrations and size distributions using a Single Particle Soot Photometer and Coulter Counter, respectively. Preliminary results

  14. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  15. Calculation of neutron albedo from laminated semiinfinite media

    International Nuclear Information System (INIS)

    Dobrynin, Yu.L.; Mikaehlyan, L.A.; Skorokhvatov, M.D.

    1978-01-01

    A version of a laminated neutron detector with increased efficiency for recording external neutron fluxes by gamma-quanta from neutron capture is considered. The detector comprises two zones. The first zone constitutes an absorbent layer (europium oxide) 0.5 cm thick, and the second one is a moderator (water with gadolinium salt at the concentration of 0.8 g/l). Mono-energetic neutrons fall normally onto the detector surface. Neutron energy varied from 0.1 eV to MeV. The results of calculations of the integral numerical current albedo (INCA) of neutrons by the Monte Carlo method are presented. The INCA dependences on neutron energy are obtained for one moderator with different gadolinium contents; for the absorbent with the moderator containing and lacking the gadolinium. The resultant dependences are indicative of preferential capture of neutrons by the gadolinium in the moderator, this being more desirable for recording neutrons in the (n, γ) reaction

  16. Water Ice Albedo Variations on the Martian Northern Polar Cap

    Science.gov (United States)

    Hale, A. S.; Bass, D. S.; Tamppari, L. K.

    2003-01-01

    The Viking Orbiters determined that the surface of Mars northern residual cap is water ice. Many researchers have related observed atmospheric water vapor abundances to seasonal exchange between reservoirs such as the polar caps, but the extent to which the exchange between the surface and the atmosphere remains uncertain. Early studies of the ice coverage and albedo of the northern residual Martian polar cap using Mariner 9 and Viking images reported that there were substantial internannual differences in ice deposition on the polar cap, a result which suggested a highly variable Martian climate. However, some of the data used in these studies were obtained at differing values of heliocentric solar longitude (L(sub s)). Reevaluation of this dataset indicated that the residual cap undergoes seasonal brightening throughout the summer, and indicated that this process repeats from year to year. In this study we continue to compare Mariner 9 and Viking Orbiter imaging observations and thermal data of the north residual polar cap to data acquired with Mars Global Surveyor s Mars Orbiter Camera (MOC) instrument. In the current study, our goal is to examine all released data from MGS MOC in the northern summer season, along with applicable TES data in order to better understand the albedo variations in the northern summer and their implications on water transport. To date, work has focused primarily on the MOC dataset. In 1999, data acquisition of the northern polar regions began at L(sub s) = 107, although there was little north polar data acquired from L(sub s)= 107 to L(sub s) = 109. We examined a total of 409 images from L(sub s) = 107 to L(sub s)=148. We have also examined data from 2000 from L(sub s)= 93 to L(sub s)= 110; additional progress is ongoing. Here we present a progress report of our observations, and continue to determine their implications for the Martian water cycle.

  17. Long-Term Variability of Surface Albedo and Its Correlation with Climatic Variables over Antarctica

    Directory of Open Access Journals (Sweden)

    Minji Seo

    2016-11-01

    Full Text Available The cryosphere is an essential part of the earth system for understanding climate change. Components of the cryosphere, such as ice sheets and sea ice, are generally decreasing over time. However, previous studies have indicated differing trends between the Antarctic and the Arctic. The South Pole also shows internal differences in trends. These phenomena indicate the importance of continuous observation of the Polar Regions. Albedo is a main indicator for analyzing Antarctic climate change and is an important variable with regard to the radiation budget because it can provide positive feedback on polar warming and is related to net radiation and atmospheric heating in the mainly snow- and ice-covered Antarctic. Therefore, in this study, we analyzed long-term temporal and spatial variability of albedo and investigated the interrelationships between albedo and climatic variables over Antarctica. We used broadband surface albedo data from the Satellite Application Facility on Climate Monitoring and data for several climatic variables such as temperature and Antarctic oscillation index (AAO during the period of 1983 to 2009. Time series analysis and correlation analysis were performed through linear regression using albedo and climatic variables. The results of this research indicated that albedo shows two trends, west trend and an east trend, over Antarctica. Most of the western side of Antarctica showed a negative trend of albedo (about −0.0007 to −0.0015 year−1, but the other side showed a positive trend (about 0.0006 year−1. In addition, albedo and surface temperature had a negative correlation, but this relationship was weaker in west Antarctica than in east Antarctica. The correlation between albedo and AAO revealed different relationships in the two regions; west Antarctica had a negative correlation and east Antarctica showed a positive correlation. In addition, the correlation between albedo and AAO was weaker in the west. This

  18. MISR Level 3 FIRSTLOOK Global Albedo product in netCDF format covering a day V002

    Data.gov (United States)

    National Aeronautics and Space Administration — The MISR Level 3 FIRSTLOOK Component Global Albedo Product in netCDF covering a day contains a statistical summary of column albedo 555 nanometer optical depth, and...

  19. MODIS/Terra+Aqua BRDF/Albedo Quality 16-Day L3 Global 1km SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODerate-resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo Quality product (MCD43B2) describes the overall condition of the other BRDF and Albedo...

  20. MODIS/Terra+Aqua BRDF/Albedo Quality 16-Day L3 Global 500m SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODerate-resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo Quality product (MCD43A2) describes the overall condition of the other BRDF and Albedo...

  1. MISR Level 3 FIRSTLOOK Global Albedo product in netCDF format covering a month V002

    Data.gov (United States)

    National Aeronautics and Space Administration — The MISR Level 3 FIRSTLOOK Component Global Albedo Product in netCDF format covering a month contains a statistical summary of column albedo 555 nanometer optical...

  2. MODIS/Terra+Aqua BRDF/Albedo Model Parameters Daily L3 Global 0.05Deg CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS MCD43C1 Version 6 Bidirectional reflectance distribution function and Albedo (BRDF/Albedo) Model Parameters data set is a 5600 meter daily 16-day product....

  3. MODIS/Terra+Aqua BRDF/Albedo Model Parameters Daily L3 Global - 500m V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS MCD43A1 Version 6 Bidirectional reflectance distribution function and Albedo (BRDF/Albedo) Model Parameters data set is a 500 meter daily 16-day product....

  4. MODIS/Terra+Aqua BRDF/Albedo Model Parameters Daily L3 Global 500m SIN Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Near Real Time (NRT) MCD43A1N, MODIS Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters is a...

  5. MODIS/Terra+Aqua BRDF/Albedo Model Parameters Daily L3 Global 0.05Deg CMG

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Near Real Time (NRT) MCD43C1N, MODIS Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters is a...

  6. Dominance of pollutant aerosols over an urban region and its impact on boundary layer temperature profile

    Science.gov (United States)

    Talukdar, Shamitaksha; Jana, Soumyajyoti; Maitra, Animesh

    2017-01-01

    Collocated measurements of aerosol optical depth (AOD) and black carbon at different wavelengths over Kolkata, an urban region in eastern India, have been used to calculate aerosol single-scattering albedo (SSA). The wavelength dependence of SSA and AOD has been presented to discriminate the aerosol types over this highly populated metropolitan area. The spectral pattern shows that SSA decreases with wavelength for most of the time in a year and corresponding Ångström coefficient is greater than unity. These optical properties indicate the dominance of fine-mode pollutant particles over the city. The temperature lapse rate profile within the surface boundary layer has been found to be significantly influenced by the heating effect of fine-mode pollutants, and consequently, the growth of the convective processes in the lower troposphere is notably affected. In addition, a back trajectory analysis has also been presented to indicate that transported air masses can have significant impact on spectral pattern of SSA.

  7. On application of the SSA method in the pulsating combustion studies

    Science.gov (United States)

    Berg, I. A.; Porshnev, S. V.; Oshchepkova, V. Y.

    2017-11-01

    Pulsating combustion is among combustion control methods used to suppress formation of NOx. An upgraded automatic setup with a direct gas injection burner was used for pulsating torch studies. Experiments resulted in obtaining time series of torch area changing in longitudinal section. Singular Spectral Analysis method (SSA) upgraded to allow for choosing the size of the window was used. Spectra of the extracted components of the time series demonstrate that they contain periodic components that match the fuel supply valve on/off cycle frequency. When increasing the control frequency the spectrum of the extracted component of the time series gets broader. With further frequency increase, the spectrum approaches that of no control action and the system operates in quasi-continuous mode. The results correspond to the results obtained earlier through the spectrum analysis that confirms the phenomenon of periodic change of the torch core area in the longitudinal section under pulsating supply of fuel.

  8. Analysis on the spatial structure of Shanghai tourism industry using the SSA method

    Directory of Open Access Journals (Sweden)

    LIU Jinwei

    2013-10-01

    Full Text Available This paper utilizes SSA method to calculate the comparative advantage of tourism industry over the other main departments in the tertiary industry in Shanghai from 2000 to 2010.The research results indicate that the structural advantage and competitive of Shanghai tourism industry are obvious,being stronger than the financial,real estate.While the developing levels among different districts are in great difference.The central metropolitan area has a higher gross value and more commercial patterns,and makes more contribution to the whole city tourism than those in suburb area;while its developing speed is slowing down.In the suburb area the gross value in tourism industry is lower,but it is increasing faster than those in urban area.The tourism industry in this area is facing with some problems as the changes in the development pattern,the cooperation of different tourism enterprises.

  9. An Investigation of Ice Surface Albedo and Its Influence on the High-Altitude Lakes of the Tibetan Plateau

    OpenAIRE

    Jiahe Lang; Shihua Lyu; Zhaoguo Li; Yaoming Ma; Dongsheng Su

    2018-01-01

    Most high-altitude lakes are more sensitive to global warming than the regional atmosphere. However, most existing climate models produce unrealistic surface temperatures on the Tibetan Plateau (TP) lakes, and few studies have focused on the influence of ice surface albedo on high-altitude lakes. Based on field albedo measurements, moderate resolution imaging spectrometer (MODIS) albedo products and numerical simulation, this study evaluates the ice albedo parameterization schemes in existing...

  10. Arctic and Antarctic diurnal and seasonal variations of snow albedo from multiyear Baseline Surface Radiation Network measurements

    OpenAIRE

    Wang, Xianwei; Zender, Charles S

    2011-01-01

    This study analyzes diurnal and seasonal variations of snow albedo at four Baseline Surface Radiation Network stations in the Arctic and Antarctica from 2003 to 2008 to elucidate similarities and differences in snow albedo diurnal cycles across geographic zones and to assess how diurnal changes in snow albedo affect the surface energy budget. At the seasonal scale, the daily albedo for the perennial snow at stations South Pole and Georg von Neumayer in Antarctica has a similar symmetric varia...

  11. Representation of vegetation effects on the snow-covered albedo in the Noah land surface model with multiple physics options

    OpenAIRE

    S. Park; S. K. Park

    2015-01-01

    Snow albedo plays a critical role in calculating the energy budget, but parameterization of the snow surface albedo is still under great uncertainty. It varies with snow grain size, snow cover thickness, snow age, forest shading factor and other variables. Snow albedo of forest is typically lower than that of short vegetation; thus snow albedo is dependent on the spatial distributions of characteristic land cover and on the canopy density and structure. In the No...

  12. The dependence of the ice-albedo feedback on atmospheric properties.

    Science.gov (United States)

    von Paris, P; Selsis, F; Kitzmann, D; Rauer, H

    2013-10-01

    Ice-albedo feedback is a potentially important destabilizing effect for the climate of terrestrial planets. It is based on the positive feedback between decreasing surface temperatures, an increase of snow and ice cover, and an associated increase in planetary albedo, which then further decreases surface temperature. A recent study shows that for M stars, the strength of the ice-albedo feedback is reduced due to the strong spectral dependence of stellar radiation and snow/ice albedos; that is, M stars primarily emit in the near IR, where the snow and ice albedo is low, and less in the visible, where the snow/ice albedo is high. This study investigates the influence of the atmosphere (in terms of surface pressure and atmospheric composition) on this feedback, since an atmosphere was neglected in previous studies. A plane-parallel radiative transfer model was used for the calculation of planetary albedos. We varied CO₂ partial pressures as well as the H₂O, CH₄, and O₃ content in the atmosphere for planets orbiting Sun-like and M type stars. Results suggest that, for planets around M stars, the ice-albedo effect is significantly reduced, compared to planets around Sun-like stars. Including the effects of an atmosphere further suppresses the sensitivity to the ice-albedo effect. Atmospheric key properties such as surface pressure, but also the abundance of radiative trace gases, can considerably change the strength of the ice-albedo feedback. For dense CO₂ atmospheres of the order of a few to tens of bar, atmospheric rather than surface properties begin to dominate the planetary radiation budget. At high CO₂ pressures, the ice-albedo feedback is strongly reduced for planets around M stars. The presence of trace amounts of H₂O and CH₄ in the atmosphere also weakens the ice-albedo effect for both stellar types considered. For planets around Sun-like stars, O₃ could also lead to a very strong decrease of the ice-albedo feedback at high CO₂ pressures.

  13. 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.

  14. Assessing spatio-temporal variability and trends in modelled and measured Greenland Ice Sheet albedo (2000-2013)

    NARCIS (Netherlands)

    Alexander, P. M.; Tedesco, M.; Fettweis, X.; Van De Wal, R. S W|info:eu-repo/dai/nl/101899556; Smeets, C. J P P|info:eu-repo/dai/nl/191522236; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643

    2014-01-01

    Accurate measurements and simulations of Greenland Ice Sheet (GrIS) surface albedo are essential, given the role of surface albedo in modulating the amount of absorbed solar radiation and meltwater production. In this study, we assess the spatio-temporal variability of GrIS albedo during June, July,

  15. 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.

  16. Low titer, isolated anti Ro/SSA 60 kd antibodies is correlated with positive pregnancy outcomes in women at risk of congenital heart block.

    Science.gov (United States)

    Tonello, Marta; Hoxha, Ariela; Mattia, Elena; Zambon, Alessandra; Visentin, Silvia; Cerutti, Alessia; Ghirardello, Anna; Milanesi, Ornella; Ruffatti, Amelia

    2017-05-01

    Congenital heart block (CHB) is an autoantibody mediated disorder presumably caused by placental transmission of maternal autoantibodies to Ro/SSA 52 kd, p200, Ro/SSA 60 kd, La/SSB ribonucleoproteins. This study investigated the clinical significance of isolated anti-Ro/SSA 52 kd, anti-p200, anti-Ro/SSA 60 kd, and anti-La/SSB antibodies in positive pregnant patients. One hundred sixty-three pregnant women positive to anti-Ro/SSA 52 kd and/or anti-Ro/SSA 60 kd and/or anti-La/SSB antibodies were prospectively enrolled in the study. Anti-Ro52, anti-Ro60, anti-p200, and anti-La antibodies were assayed using home-made ELISA assays. Isolated antibody positivity was found in 25 women (15.3%), while multiple antibody positivity in 138 (84.7%). Twenty-four developed CHB, and the 139 had a favorable pregnancy outcome. The prevalence of isolated anti-Ro/SSA 60 kd antibodies was significantly higher (p Ro/SSA 60 kd antibodies.

  17. 75 FR 30839 - Privacy Act of 1974; CMS Computer Match No. 2010-03, HHS Computer Match No. 1003, SSA Computer...

    Science.gov (United States)

    2010-06-02

    ... Match No. 1003 SSA Computer Match No. 1048 IRS Project No. 241 NAME: ``Medicare Secondary Payer (MSP... 1974; CMS Computer Match No. 2010-03, HHS Computer Match No. 1003, SSA Computer Match No. 1048, IRS Project No. 241 AGENCY: Department of Health and Human Services (HHS), Centers for Medicare & Medicaid...

  18. Validation study - on-road evaluation of the Cooperative Intersection Collision Avoidance System - Stop Sign Assist sign : (CICAS-SSA Report #5).

    Science.gov (United States)

    2009-11-01

    The CICAS-SSA sign is a roadside driver support system that is intended to improve gap rejection at rural stop-controlled intersections. The CICAS-SSA system tracks vehicle locations on a major roadway and then displays a message to a driver on the m...

  19. 20 CFR 411.321 - Under what conditions will SSA terminate an agreement with an EN due to inadequate performance?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Under what conditions will SSA terminate an agreement with an EN due to inadequate performance? 411.321 Section 411.321 Employees' Benefits SOCIAL SECURITY ADMINISTRATION THE TICKET TO WORK AND SELF-SUFFICIENCY PROGRAM Employment Networks § 411.321 Under...

  20. Outcome in 212 anti-Ro/SSA-positive pregnancies and population-based incidence of congenital heart block.

    Science.gov (United States)

    Skog, Amanda; Lagnefeldt, Linda; Conner, Peter; Wahren-Herlenius, Marie; Sonesson, Sven-Erik

    2016-01-01

    We investigated the effects of maternal autoimmune disease and fetal congenital heart block (CHB) on pregnancy outcomes in anti-Ro/SSA-positive women and assessed the population-based incidence of isolated CHB. One hundred and ninety nine anti-Ro/SSA-positive pregnancies were prospectively followed at our center (2000-2013). Seven fetuses developed atrioventricular block (AVB) II-III. In this period, another 13 anti-Ro/SSA-positive pregnancies were referred for fetal bradycardia, subsequently diagnosed with AVB II-III. Cesarean section rates, gestational age, body measurements at birth, and the incidence of CHB in these 212 pregnancies were analyzed in relation to fetal atrioventricular conduction and maternal diagnosis and compared with data from the Medical Birth Registry on 352,104 pregnancies in the Stockholm County. The prevalence of maternal systemic lupus erythematosus (SLE) and primary Sjögren's syndrome and the outcomes at birth were similar in normal conduction and AVB I cases. Only 1/20 AVB II-III cases (0/7 in the surveillance group) had a mother diagnosed with SLE, compared with 73/192 in cases with normal conduction or AVB I. Excluding cases with AVB II-III, SLE mothers more frequently delivered by cesarean section (31% vs. 20%, p Ro/SSA-positive women, which has clinical relevance when counseling rheumatic patients considering pregnancy. © 2015 Nordic Federation of Societies of Obstetrics and Gynecology.

  1. Persistent fetal sinus bradycardia associated with maternal anti-SSA/Ro and anti-SSB/La antibodies

    NARCIS (Netherlands)

    Chockalingam, Priya; Jaeggi, Edgar T.; Rammeloo, Lukas A.; Haak, Monique C.; Adama van Scheltema, Phebe N.; Breur, Johannes M. P. J.; Bartelings, Margot M.; Clur, Sally-Ann B.; Blom, Nico A.

    2011-01-01

    To study the clinical course and outcome of fetal sinus bradycardia (SB) due to maternal antibody-induced sinus node dysfunction. We reviewed the maternal, prenatal, and postnatal findings of fetuses with SB associated with elevated maternal anti-SSA/Ro and anti-SSB/La antibodies. Of the 6 cases

  2. 76 FR 77238 - Submission for OMB Review; Comment Request; The SSA-NIH Collaboration to Improve the Disability...

    Science.gov (United States)

    2011-12-12

    ... Collaboration to Improve the Disability Determination Process: Validation of IRT-CAT tools. Type of Information...; Comment Request; The SSA-NIH Collaboration to Improve the Disability Determination Process: Validation of... in RMD will be collecting information through a contractor (Boston University- Health and Disability...

  3. 76 FR 12397 - Privacy Act of 1974, as Amended; Computer Matching Program (SSA/Bureau of the Public Debt (BPD...

    Science.gov (United States)

    2011-03-07

    ...; Computer Matching Program (SSA/ Bureau of the Public Debt (BPD))--Match Number 1038 AGENCY: Social Security... 1795. The relevant BPD SORs are Treasury/ BPD.002, United States Savings Type Securities, and Treasury... containing SSNs extracted from the Supplemental Security Record database. Exchanges for this computer...

  4. 78 FR 69925 - Privacy Act of 1974, as Amended; Computer Matching Program (SSA/Bureau of the Fiscal Service...

    Science.gov (United States)

    2013-11-21

    ... savings securities. C. Authority for Conducting the Matching Program This computer matching agreement sets..., United States Savings Type Securities, and Treasury/BPD.008, Retail Treasury Securities Access... SOCIAL SECURITY ADMINISTRATION [Docket No. SSA 2013-0058] Privacy Act of 1974, as Amended...

  5. Estimation of Instantaneous TOA Albedo at 670 nm over Ice Clouds from POLDER Multidirectional Measurements

    Science.gov (United States)

    Sun, W.; Loeb, N. G.; Kato, S.

    2003-01-01

    An algorithm that determines the 670-nm top-of-atmosphere (TOA) albedo of ice clouds over ocean using Polarization and Directionality of the Earth's Reflectance ( POLDER) multidirectional measurements is developed. A plane-parallel layer of ice cloud with various optical thicknesses and light scattering phase functions is assumed. For simplicity, we use a double Henyey-Greenstein phase function to approximate the volume-averaged phase function of the ice clouds. A multidirectional reflectance best-fit match between theoretical and POLDER reflectances is used to infer effective cloud optical thickness, phase function and TOA albedo. Sensitivity tests show that while the method does not provide accurate independent retrievals of effective cloud optical depth and phase function, TOA albedo retrievals are accurate to within similar to 3% for both a single layer of ice clouds or a multilayer system of ice clouds and water clouds. When the method is applied to POLDER measurements and retrieved albedos are compared with albedos based on empirical angular distribution models (ADMs), zonal albedo differences are generally smaller than similar to 3%. When albedos are compared with those on the POLDER-I ERB and Cloud product, the differences can reach similar to 15% at small solar zenith angles.

  6. Mapping Surface Broadband Albedo from Satellite Observations: A Review of Literatures on Algorithms and Products

    Directory of Open Access Journals (Sweden)

    Ying Qu

    2015-01-01

    Full Text Available Surface albedo is one of the key controlling geophysical parameters in the surface energy budget studies, and its temporal and spatial variation is closely related to the global climate change and regional weather system due to the albedo feedback mechanism. As an efficient tool for monitoring the surfaces of the Earth, remote sensing is widely used for deriving long-term surface broadband albedo with various geostationary and polar-orbit satellite platforms in recent decades. Moreover, the algorithms for estimating surface broadband albedo from satellite observations, including narrow-to-broadband conversions, bidirectional reflectance distribution function (BRDF angular modeling, direct-estimation algorithm and the algorithms for estimating albedo from geostationary satellite data, are developed and improved. In this paper, we present a comprehensive literature review on algorithms and products for mapping surface broadband albedo with satellite observations and provide a discussion of different algorithms and products in a historical perspective based on citation analysis of the published literature. This paper shows that the observation technologies and accuracy requirement of applications are important, and long-term, global fully-covered (including land, ocean, and sea-ice surfaces, gap-free, surface broadband albedo products with higher spatial and temporal resolution are required for climate change, surface energy budget, and hydrological studies.

  7. Near-ground cooling efficacies of trees and high-albedo surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen M. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequently-proposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object`s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by.

  8. Analysis of earth albedo effect on sun sensor measurements based on theoretical model and mission experience

    Science.gov (United States)

    Brasoveanu, Dan; Sedlak, Joseph

    1998-01-01

    Analysis of flight data from previous missions indicates that anomalous Sun sensor readings could be caused by Earth albedo interference. A previous Sun sensor study presented a detailed mathematical model of this effect. The model can be used to study the effect of both diffusive and specular reflections and to improve Sun angle determination based on perturbed Sun sensor measurements, satellite position, and an approximate knowledge of attitude. The model predicts that diffuse reflected light can cause errors of up to 10 degrees in Coarse Sun Sensor (CSS) measurements and 5 to 10 arc sec in Fine Sun Sensor (FSS) measurements, depending on spacecraft orbit and attitude. The accuracy of these sensors is affected as long as part of the illuminated Earth surface is present in the sensor field of view. Digital Sun Sensors (DSS) respond in a different manner to the Earth albedo interference. Most of the time DSS measurements are not affected, but for brief periods of time the Earth albedo can cause errors which are a multiple of the sensor least significant bit and may exceed one degree. This paper compares model predictions with Tropical Rainfall Measuring Mission (TRMM) CSS measurements in order to validate and refine the model. Methods of reducing and mitigating the impact of Earth albedo are discussed. ne CSS sensor errors are roughly proportional to the Earth albedo coefficient. Photocells that are sensitive only to ultraviolet emissions would reduce the effective Earth albedo by up to a thousand times, virtually eliminating all errors caused by Earth albedo interference.

  9. Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Snow Albedo Product (MCD43A) over Tundra

    Science.gov (United States)

    Wang, Zhuosen; Schaaf, Crystal B.; Chopping, Mark J.; Strahler, Alan H.; Wang, Jindi; Roman, Miguel O.; Rocha, Adrian V.; Woodcock, Curtis E.; Shuai, Yanmin

    2012-01-01

    This study assesses the MODIS standard Bidirectional Reflectance Distribution Function (BRDF)/Albedo product, and the daily Direct Broadcast BRDF/Albedo algorithm at tundra locations under large solar zenith angles and high anisotropic diffuse illumination and multiple scattering conditions. These products generally agree with ground-based albedo measurements during the snow cover period when the Solar Zenith Angle (SZA) is less than 70deg. An integrated validation strategy, including analysis of the representativeness of the surface heterogeneity, is performed to decide whether direct comparisons between field measurements and 500- m satellite products were appropriate or if the scaling of finer spatial resolution airborne or spaceborne data was necessary. Results indicate that the Root Mean Square Errors (RMSEs) are less than 0.047 during the snow covered periods for all MCD43 albedo products at several Alaskan tundra areas. The MCD43 1- day daily albedo product is particularly well suited to capture the rapidly changing surface conditions during the spring snow melt. Results also show that a full expression of the blue sky albedo is necessary at these large SZA snow covered areas because of the effects of anisotropic diffuse illumination and multiple scattering. In tundra locations with dark residue as a result of fire, the MODIS albedo values are lower than those at the unburned site from the start of snowmelt.

  10. Improvement of Mars surface snow albedo modeling in LMD Mars GCM with SNICAR

    Science.gov (United States)

    Singh, D.; Flanner, M.; Millour, E.

    2017-12-01

    The current version of Laboratoire de Météorologie Dynamique (LMD) Mars GCM (original-MGCM) uses annually repeating (prescribed) albedo values from the Thermal Emission Spectrometer observations. We integrate the Snow, Ice, and Aerosol Radiation (SNICAR) model with MGCM (SNICAR-MGCM) to prognostically determine H2O and CO2 ice cap albedos interactively in the model. Over snow-covered regions mean SNICAR-MGCM albedo is higher by about 0.034 than original-MGCM. Changes in albedo and surface dust content also impact the shortwave energy flux at the surface. SNICAR-MGCM model simulates a change of -1.26 W/m2 shortwave flux on a global scale. Globally, net CO2 ice deposition increases by about 4% over one Martian annual cycle as compared to original-MGCM simulations. SNICAR integration reduces the net mean global surface temperature, and the global surface pressure of Mars by about 0.87% and 2.5% respectively. Changes in albedo also show a similar distribution as dust deposition over the globe. The SNICAR-MGCM model generates albedos with higher sensitivity to surface dust content as compared to original-MGCM. For snow-covered regions, we improve the correlation between albedo and optical depth of dust from -0.91 to -0.97 with SNICAR-MGCM as compared to original-MGCM. Using new diagnostic capabilities with this model, we find that cryospheric surfaces (with dust) increase the global surface albedo of Mars by 0.022. The cryospheric effect is severely muted by dust in snow, however, which acts to decrease the planet-mean surface albedo by 0.06.

  11. Albedo enhancement over land to counteract global warming: impacts on hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bala, Govindasamy; Nag, Bappaditya [Indian Institute of Science, Divecha Center for Climate Change and Center for Atmospheric and Oceanic Sciences, Bangalore (India)

    2012-09-15

    A recent modelling study has shown that precipitation and runoff over land would increase when the reflectivity of marine clouds is increased to counter global warming. This implies that large scale albedo enhancement over land could lead to a decrease in runoff over land. In this study, we perform simulations using NCAR CAM3.1 that have implications for Solar Radiation Management geoengineering schemes that increase the albedo over land. We find that an increase in reflectivity over land that mitigates the global mean warming from a doubling of CO{sub 2} leads to a large residual warming in the southern hemisphere and cooling in the northern hemisphere since most of the land is located in northern hemisphere. Precipitation and runoff over land decrease by 13.4 and 22.3%, respectively, because of a large residual sinking motion over land triggered by albedo enhancement over land. Soil water content also declines when albedo over land is enhanced. The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (-8.2 W m{sup -2}) to counter global mean radiative forcing from a doubling of CO{sub 2} (3.3 W m{sup -2}) is approximately twice the forcing needed over the oceans (-4.2 W m{sup -2}). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface albedo such as deforestation/afforestation/reforestation, air pollution, and desert and urban albedo modification. (orig.)

  12. Estimation of surface albedo from NOAA AVHRR data in high latitudes

    Science.gov (United States)

    Laine, Vesa; Heikinheimo, Martti

    1996-05-01

    A method for determining the surface albedo from routine daily NOAA AVHRR data is described and tested for applicability under high latitude conditions in a boreal-sub-arctic region. The test period included all received satellite data from April to October 1994, giving a good coverage of various and changing surface conditions. Albedo values obtained initially for each cloud-free pixel and satellite over-pass were averaged over nine-day periods to include a full cycle of measuring geometries and to obtain an adequate number of cloud-free pixels in the final average images. With the automated image navigation provided by the present receiving system, spatial averaging over a minimum of 24×24 pixel squares was needed to obtain acceptable repeatability of local albedo values. The atmospheric correction was made using a bi-directional atmospheric correction method. In early April, the albedo over the sea in the ice-covered northern Gulf of Bothnia and in the open mountain regions was typically above 60%. Over snow-covered forested areas, the albedo was near 50% in the sub-arctic zone, and near 30% for the central boreal forest-covered surface. The difference in albedo between the northern and southern forested locations in the presence of snow was attributed to the higher biomass density of forests in the south and possibly more snow remaining on trees in the north. For snow-free conditions, forested areas typically showed an albedo in the range 11 13%. Agricultural regions, mixed with minor patches of forest, generally showed an albedo below 15% for conditions of low crop leaf area coverage, but reached as high as 18% under conditions of maximum leaf area coverage in mid-summer. Retrieval of the edge of snow cover in spring and the appearance of newly fallen snow in autumn could readily be carried out using a threshold albedo of 20%.

  13. Deriving albedo maps for HAPEX-Sahel from ASAS data using kernel-driven BRDF models

    Directory of Open Access Journals (Sweden)

    P. Lewis

    1999-01-01

    Full Text Available This paper describes the application and testing of a method for deriving spatial estimates of albedo from multi-angle remote sensing data. Linear kernel-driven models of surface bi-directional reflectance have been inverted against high spatial resolution multi-angular, multi- spectral airborne data of the principal cover types within the HAPEX-Sahel study site in Niger, West Africa. The airborne data are obtained from the NASA Airborne Solid-state Imaging Spectrometer (ASAS instrument, flown in Niger in September and October 1992. The maps of model parameters produced are used to estimate integrated reflectance properties related to spectral albedo. Broadband albedo has been estimated from this by weighting the spectral albedo for each pixel within the map as a function of the appropriate spectral solar irradiance and proportion of direct and diffuse illumination. Partial validation of the results was performed by comparing ASAS reflectance and derived directional-hemispherical reflectance with simulations of a millet canopy made with a complex geometric canopy reflectance model, the Botanical Plant Modelling System (BPMS. Both were found to agree well in magnitude. Broadband albedo values derived from the ASAS data were compared with ground-based (point sample albedo measurements and found to agree extremely well. These results indicate that the linear kernel-driven modelling approach, which is to be used operationally to produce global 16 day, 1 km albedo maps from forthcoming NASA Earth Observing System spaceborne data, is both sound and practical for the estimation of angle-integrated spectral reflectance quantities related to albedo. Results for broadband albedo are dependent on spectral sampling and on obtaining the correct spectral weigthings.

  14. Global albedos of Pluto and Charon from LORRI New Horizons observations

    Science.gov (United States)

    Buratti, B. J.; Hofgartner, J. D.; Hicks, M. D.; Weaver, H. A.; Stern, S. A.; Momary, T.; Mosher, J. A.; Beyer, R. A.; Verbiscer, A. J.; Zangari, A. M.; Young, L. A.; Lisse, C. M.; Singer, K.; Cheng, A.; Grundy, W.; Ennico, K.; Olkin, C. B.

    2017-05-01

    The exploration of the Pluto-Charon system by the New Horizons spacecraft represents the first opportunity to understand the distribution of albedo and other photometric properties of the surfaces of objects in the Solar System's ;Third Zone; of distant ice-rich bodies. Images of the entire illuminated surface of Pluto and Charon obtained by the Long Range Reconnaissance Imager (LORRI) camera provide a global map of Pluto that reveals surface albedo variegations larger than any other Solar System world except for Saturn's moon Iapetus. Normal reflectances on Pluto range from 0.08-1.0, and the low-albedo areas of Pluto are darker than any region of Charon. Charon exhibits a much blander surface with normal reflectances ranging from 0.20-0.73. Pluto's albedo features are well-correlated with geologic features, although some exogenous low-albedo dust may be responsible for features seen to the west of the area informally named Tombaugh Regio. The albedo patterns of both Pluto and Charon are latitudinally organized, with the exception of Tombaugh Regio, with darker regions concentrated at the Pluto's equator and Charon's northern pole. The phase curve of Pluto is similar to that of Triton, the large moon of Neptune believed to be a captured Kuiper Belt Object (KBO), while Charon's is similar to that of the Moon. Preliminary Bond albedos are 0.25 ± 0.03 for Charon and 0.72 ± 0.07 for Pluto. Maps of an approximation to the Bond albedo for both Pluto and Charon are presented for the first time. Our work shows a connection between very high albedo (near unity) and planetary activity, a result that suggests the KBO Eris may be currently active.

  15. A note on solar elevation dependence of clear sky snow albedo

    Science.gov (United States)

    Choudhury, B. J.

    1981-01-01

    Recent attempts to match shortwave albedo of snow for clear skies using approximate spectral solar fluxes and solutions of the radiative transfer equation for snow were unsuccessful until a separate surface reflection term was introduced. A separate consideration of specular reflection from surface snow grains has been objected to as being ad hoc. Results based on a new parameterization of shortwave radiation are discussed. Compared to the previous radiation models, new model gives higher diffuse insolation and predicts higher albedos. The difference between observed and predicted albedos is substantially reduced without invoking surface reflection.

  16. Empirical models of monthly and annual surface albedo in managed boreal forests of Norway

    Science.gov (United States)

    Bright, Ryan M.; Astrup, Rasmus; Strømman, Anders H.

    2013-04-01

    As forest management activities play an increasingly important role in climate change mitigation strategies of Nordic regions such as Norway, Sweden, and Finland -- the need for a more comprehensive understanding of the types and magnitude of biogeophysical climate effects and their various tradeoffs with the global carbon cycle becomes essential to avoid implementation of sub-optimal policy. Forest harvest in these regions reduces the albedo "masking effect" and impacts Earth's radiation budget in opposing ways to that of concomitant carbon cycle perturbations; thus, policies based solely on biogeochemical considerations in these regions risk being counterproductive. There is therefore a need to better understand how human disturbances (i.e., forest management activities) affect important biophysical factors like surface albedo. An 11-year remotely sensed surface albedo dataset coupled with stand-level forest management data for a variety of stands in Norway's most productive logging region are used to develop regression models describing temporal changes in monthly and annual forest albedo following clear-cut harvest disturbance events. Datasets are grouped by dominant tree species and site indices (productivity), and two alternate multiple regression models are developed and tested following a potential plus modifier approach. This resulted in an annual albedo model with statistically significant parameters that explains a large proportion of the observed variation, requiring as few as two predictor variables: i) average stand age - a canopy modifier predictor of albedo, and ii) stand elevation - a local climate predictor of a forest's potential albedo. The same model structure is used to derive monthly albedo models, with models for winter months generally found superior to summer models, and conifer models generally outperforming deciduous. We demonstrate how these statistical models can be applied to routine forest inventory data to predict the albedo

  17. Hydrocarbon photochemistry and Lyman alpha albedo of Jupiter

    Science.gov (United States)

    Yung, Y. L.; Strobel, D. F.

    1980-01-01

    A combined study of hydrocarbon and atomic hydrogen photochemistry is made to calculate self-consistently the L alpha albedo of Jupiter. It is shown that the L alpha emissions observed by Voyagers I and II can be explained by resonance scattering of sunlight. Precipitation of energetic particles from the magnetosphere can provide the large required source of atomic hydrogen, although the contribution of direct particle excitation to the disk-averaged brightness is insignificant. The variability of the L alpha brightness inferred from many observations in recent years is examined. The large difference in the brightness of the He 584 A resonance line observed by Pioneer and Voyager is briefly discussed. Driving the photochemistry by solar ultraviolet radiation alone yields a maximum mixing ratio of C2H6 + C2H2 at 0.01 atm of about 4 x 10 to the -6th. The possibility of additional CH4 dissociation from precipitation of magnetospheric particles is discussed. The photochemistry of C2H2 and C2H3 is sufficiently uncertain not to permit accurate calculations of their densities and the ratio C2H6/C2H2.

  18. Constraining the instantaneous aerosol influence on cloud albedo

    Energy Technology Data Exchange (ETDEWEB)

    Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine; Gettelman, Andrew; Ghan, Steven; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G.; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Wang, Minghuai; Zhang, Kai

    2017-04-26

    Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.

  19. Constraining the instantaneous aerosol influence on cloud albedo

    Science.gov (United States)

    Quaas, Johannes; Ferrachat, Sylvaine; Gettelman, Andrew; Ghan, Steven; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G.; Takemura, Toshihiko; Wang, Hailong; Wang, Minghuai; Zhang, Kai

    2017-01-01

    Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data. PMID:28446614

  20. NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos

    Energy Technology Data Exchange (ETDEWEB)

    Masiero, Joseph R.; Mainzer, A. K.; Kramer, E. [Jet Propulsion Laboratory/California Institute of Technology, 4800 Oak Grove Drive, MS 183-301, Pasadena, CA 91109 (United States); Nugent, C.; Cutri, R. M. [California Institute of Technology, Infrared Processing and Analysis Center, 1200 California Boulevard, Pasadena, CA 91125 (United States); Wright, E. L. [University of California, Los Angeles, CA 90095 (United States); Bauer, J. M. [University of Maryland, College Park, MD 20742 (United States); Grav, T.; Sonnett, S., E-mail: Joseph.Masiero@jpl.nasa.gov [Planetary Science Institute, 1700 E Fort Lowell Road #106, Tucson, AZ 85719 (United States)

    2017-10-01

    The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) reactivation mission has completed its third year of surveying the sky in the thermal infrared for near-Earth asteroids and comets. NEOWISE collects simultaneous observations at 3.4 and 4.6  μ m of solar system objects passing through its field of regard. These data allow for the determination of total thermal emission from bodies in the inner solar system, and thus the sizes of these objects. In this paper, we present thermal model fits of asteroid diameters for 170 NEOs and 6110 Main Belt asteroids (MBAs) detected during the third year of the survey, as well as the associated optical geometric albedos. We compare our results with previous thermal model results from NEOWISE for overlapping sample sets, as well as diameters determined through other independent methods, and find that our diameter measurements for NEOs agree to within 26% (1 σ ) of previously measured values. Diameters for the MBAs are within 17% (1 σ ). This brings the total number of unique near-Earth objects characterized by the NEOWISE survey to 541, surpassing the number observed during the fully cryogenic mission in 2010.

  1. The influence of quorum sensing in compartment II of the MELiSSA loop

    Science.gov (United States)

    Condori, Sandra; Mastroleo, Felice; Wattiez, Ruddy; Leys, Natalie

    MELiSSA (Micro-Ecological Life Support System Alternative) has been conceived as a 5 compartments microorganisms and higher plants recycling system for long haul space flights. Rhodospirillum rubrum S1H colonizes compartment II. Previous work reported that continuous culture of the bacterium in a photobioreactor could lead to thick biofilm formation, leading to bioreactor arrest. Our aim is to investigate the unknown quorum sensing (QS) system of R. rubrum S1H, specifically under MELiSSA relevant culture conditions meaning light anaerobic (LAN) and using acetate as carbon source. In that purpose an autoinducer synthase gene (Rru_A3396) knockout mutant was constructed by allelic exchange generating strain M68. In addition phenotypic comparison between wild type (WT) and M68 was performed. Results of thin layer chromatography assay where Agrobacterium tumefaciens NT1 have been used as reporter strain showed that WT produces acyl-homoserine lactones (AHLs) from C4 to C12 acyl carbon chain length; however, in M68 no AHLs were detected confirming that gene Rru_A3396 (named rruI) encodes an autoinducer synthase. Interestingly under a low shear or static environment M68 showed cell aggregation similar as reported in a closely related bacterium Rhodobacter sphaeroides (cerI mutant). In contrast to WT, M68 did not form biofilm and exhibited a decreased motility and pigment content. M68 vs wild type transcriptomics results showed that 326 genes were statistically significant differentially expressed. Downregulation of genes related to photosynthesis e.g., reaction center subunits, light harvesting complex and photosynthetic assembly proteins was observed. Similar results were obtained for preliminary proteomic analysis. Results obtained showed that in R. rubrum S1H the AHL-based QS system regulates almost 8% of the genome which is linked to biofilm formation among other biological processes described above. Since strain M68 could not be used in compartment II due to its less

  2. Atmospheric effects on the mapping of Martian thermal inertia and thermally derived albedo

    Science.gov (United States)

    Hayashi, Joan N.; Jakosky, Bruce M.; Haberle, Robert M.

    1995-01-01

    We examine the effects of a dusty C02 atmosphere on the thermal inertia and thermally derived albedo of Mars and we present a new map of thermal inertias. This new map was produced using a coupled surface atmosphere (CSA) model, dust opacities from Viking infrared thermal mapper (IRTM) data, and C02 columns based on topography. The CSA model thermal inertias are smaller than the 2% model thermal inertias, with the difference largest at large thermal inertia. Although the difference between the thermal inertias obtained with the two models is moderate for much of the region studied, it is largest in regions of either high dust opacity or of topographic lows, including the Viking Lander 1 site and some geologically interesting regions. The CSA model thermally derived albedos do not accurately predict the IRTM measured albedos and are very similar to the thermally derived albedos obtained with models making the 2% assumption.

  3. SAFARI 2000 Surface Albedo and Radiation Fluxes at Mongu and Skukuza, 2000-2002

    Data.gov (United States)

    National Aeronautics and Space Administration — Top-of-the-canopy broadband albedo and radiation fluxes are calculated from measurements at the Mongu and Skukuza flux tower sites in southern Africa from March 2000...

  4. ISLSCP II Monthly Snow-Free Albedo, 1982-1998, and Background Soil Reflectance

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains monthly average snow-free surface shortwave albedo calculated for the period 1982-1998 and estimates of background soil/litter reflectances in...

  5. On the calibration of the polarimetric slope - albedo relation for asteroids: Work in progress

    Directory of Open Access Journals (Sweden)

    A. Cellino

    2011-09-01

    Full Text Available Asteroid polarimetry is known to be an excellent tool to derive information on the geometric albedo of these objects. This is made possible by the existence of a relation between the albedo and the morphology of the curve which describes the variation of the degree of linear polarization of asteroid light as a function of the illumination conditions. A major problem is that the calibration of the commonly accepted form of the polarization - albedo relation includes numerical coefficients which are affected by fairly high uncertainties. Following some recommendations issued by IAU Commission 15, we are trying to improve the albedo - polarization relation by taking advantage of new polarimetric data obtained in dedicated observation campaigns. We present here some very preliminary results.

  6. Spatially Complete Surface Albedo Data Sets: Value-Added Products Derived from Terra MODIS Land Products

    Science.gov (United States)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. Recent observations of diffuse bihemispherical (white-sky) and direct beam directional hemispherical (black-sky ) land surface albedo included in the MOD43B3 product from MODIS instruments aboard NASA's Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal characteristics. Cloud and seasonal snow cover, however, curtail retrievals to approximately half the global land surfaces on an annual equal-angle basis, precluding MOD43B3 albedo products from direct inclusion in some research projects and production environments.

  7. Development of a Multilayer MODIS IST-Albedo Product of Greenland

    Science.gov (United States)

    Hall, D. K.; Comiso, J. C.; Cullather, R. I.; Digirolamo, N. E.; Nowicki, S. M.; Medley, B. C.

    2017-01-01

    A new multilayer IST-albedo Moderate Resolution Imaging Spectroradiometer (MODIS) product of Greenland was developed to meet the needs of the ice sheet modeling community. The multiple layers of the product enable the relationship between IST and albedo to be evaluated easily. Surface temperature is a fundamental input for dynamical ice sheet models because it is a component of the ice sheet radiation budget and mass balance. Albedo influences absorption of incoming solar radiation. The daily product will combine the existing standard MODIS Collection-6 ice-surface temperature, derived melt maps, snow albedo and water vapor products. The new product is available in a polar stereographic projection in NetCDF format. The product will ultimately extend from March 2000 through the end of 2017.

  8. ISLSCP II NOAA 5-year Average Monthly Snow-free Albedo from AVHRR

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The objective of this work was to produce a monthly climatology of broadband surface albedos for use in global numerical weather prediction models at the...

  9. ISLSCP II NOAA 5-year Average Monthly Snow-free Albedo from AVHRR

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this work was to produce a monthly climatology of broadband surface albedos for use in global numerical weather prediction models at the National...

  10. Seasonal albedo of an urban/rural landscape from satellite observations

    Science.gov (United States)

    Brest, Christopher L.

    1987-01-01

    Using data from 27 calibrated Landsat observations of the Hartford, Connecticut area, the spatial distribution and seasonal variation of surface reflectance and albedo were examined. Mean values of visible reflectance, near-IR reflectance, and albedo are presented (for both snow-free and snow-cover observations) according to 14 land use/land cover categories. A diversity of albedo values was found to exist in this type of environment, associated with land cover. Many land-cover categories display a seasonal dependence, with intracategory seasonal differences being of comparable magnitude to intercategory differences. Key factors in determining albedo (and its seasonal dynamics) are the presence or absence of vegetation and the canopy structure. Snow-cover/snow-free differences range from a few percent (for urban land covers) to over 40 percent (for low-canopy vegetation).

  11. Arctic sea ice albedo - A comparison of two satellite-derived data sets

    Science.gov (United States)

    Schweiger, Axel J.; Serreze, Mark C.; Key, Jeffrey R.

    1993-01-01

    Spatial patterns of mean monthly surface albedo for May, June, and July, derived from DMSP Operational Line Scan (OLS) satellite imagery are compared with surface albedos derived from the International Satellite Cloud Climatology Program (ISCCP) monthly data set. Spatial patterns obtained by the two techniques are in general agreement, especially for June and July. Nevertheless, systematic differences in albedo of 0.05 - 0.10 are noted which are most likely related to uncertainties in the simple parameterizations used in the DMSP analyses, problems in the ISCCP cloud-clearing algorithm and other modeling simplifications. However, with respect to the eventual goal of developing a reliable automated retrieval algorithm for compiling a long-term albedo data base, these initial comparisons are very encouraging.

  12. Quality assurance of in-situ measurements of land surface albedo: A model-based approach

    Science.gov (United States)

    Adams, Jennifer; Gobron, Nadine; Widlowski, Jean-Luc; Mio, Corrado

    2016-04-01

    This paper presents the development of a model-based framework for assessing the quality of in-situ measurements of albedo used to validate land surface albedo products. Using a 3D Monte Carlo Ray Tracing (MCRT) radiative transfer model, a quality assurance framework is built based on simulated field measurements of albedo within complex 3D canopies and under various illumination scenarios. This method provides an unbiased approach in assessing the quality of field measurements, and is also able to trace the contributions of two main sources of uncertainty in field-measurements of albedo; those resulting from 1) the field measurement protocol, such as height or placement of field measurement within the canopy, and 2) intrinsic factors of the 3D canopy under specific illumination characteristics considered, such as the canopy structure and landscape heterogeneity, tree heights, ecosystem type and season.

  13. The surface abundance and stratigraphy of lunar rocks from data about their albedo

    Science.gov (United States)

    Shevchenko, V. V.

    1977-01-01

    The data pf ground-based studies and surveys of the lunar surface by the Zond and Apollo spacecraft have been used to construct an albedo map covering 80 percent of the lunar sphere. Statistical analysis of the distribution of areas with various albedos shows several types of lunar surface. Comparison of albedo data for maria and continental areas with the results of geochemical orbital surveys allows the identification of the types of surface with known types of lunar rock. The aluminum/silcon and magnesium/silicon ratios as measured by the geochemical experiments on the Apollo 15 and Apollo 16 spacecraft were used as an indication of the chemical composition of the rock. The relationship of the relative aluminum content to the age of crystalline rocks allows a direct dependence to be constructed between the mean albedo of areas and the age of the rocks of which they are composed.

  14. ISLSCP II Monthly Snow-Free Albedo, 1982-1998, and Background Soil Reflectance

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains monthly average snow-free surface shortwave albedo calculated for the period 1982-1998 and estimates of background soil/litter...

  15. The extreme ultraviolet albedos of the planet Mercury and of the moon

    Science.gov (United States)

    Wu, H. H.; Broadfoot, A. L.

    1977-01-01

    The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.

  16. Comparison between Snow Albedo Obtained from Landsat TM, ETM+ Imagery and the SPOT VEGETATION Albedo Product in a Mediterranean Mountainous Site

    Directory of Open Access Journals (Sweden)

    Rafael Pimentel

    2016-02-01

    Full Text Available Albedo plays an important role in snow evolution modeling quantifying the amount of solar radiation absorbed and reflected by the snowpack, especially in mid-latitude regions with semiarid conditions. Satellite remote sensing is the most extensive technique to determine the variability of snow albedo over medium to large areas; however, scale effects from the pixel size of the sensor source may affect the results of snow models, with different impacts depending on the spatial resolution. This work presents the evaluation of snow albedo values retrieved from (1 Landsat images, L (16-day frequency with 30 × 30 m pixel size and (2 SPOT VEGETATION albedo products, SV (10-day frequency with 1 × 1 km pixel size in the Sierra Nevada mountain range in South Spain, a Mediterranean site representative of highly heterogeneous conditions. Daily snow albedo map series were derived from both sources, and used as input for the snow module in the WiMMed (Watershed Integrated Management in Mediterranean Environment hydrological model, which was operational at the study area for snow monitoring for two hydrological years, 2011–2012 and 2012–2013, in the Guadalfeo river basin in Sierra Nevada. The results showed similar albedo trends in both data sources, but with different values, the shift between both sources being distributed in space according to the altitude. This difference resulted in lower snow cover fraction values in the SV-simulations that affected the rest of snow variables included in the simulation. This underestimation, mainly due to the effects of mixed pixels composed by both snow and snow-free areas, produced higher divergences from both sources during the melting periods when the evapo-sublimation and melting fluxes are more relevant. Therefore, the selection of the albedo data source in these areas, where snow evapo-sublimation plays a very important role and the presence of snow-free patches is very frequent, can condition the final

  17. Glacier albedo decrease in the European Alps: potential causes and links with mass balances

    Science.gov (United States)

    Di Mauro, Biagio; Julitta, Tommaso; Colombo, Roberto

    2016-04-01

    Both mountain glaciers and polar ice sheets are losing mass all over the Earth. They are highly sensitive to climate variation, and the widespread reduction of glaciers has been ascribed to the atmospheric temperature increase. Beside this driver, also ice albedo plays a fundamental role in defining mass balance of glaciers. In fact, dark ice absorbs more energy causing faster glacier melting, and this can drive to more negative balances. Previous studies showed that the albedo of Himalayan glaciers and the Greenland Ice Sheet is decreasing with important rates. In this contribution, we tested the hypothesis that also glaciers in the European Alps are getting darker. We analyzed 16-year time series of MODIS (MODerate resolution Imaging Spectrometer) snow albedo from Terra (MOD13A1, 2000-2015) and Aqua (MYD13A1, 2002-2015) satellites. These data feature a spatial resolution of 500m and a daily temporal resolution. We evaluated the existence of a negative linear and nonlinear trend of the summer albedo values both at pixel and at glacier level. We also calculated the correlation between MODIS summer albedo and glacier mass balances (from the World Glaciological Monitoring Service, WGMS database), for all the glaciers with available mass balance during the considered period. In order to estimate the percentage of the summer albedo that can be explained by atmospheric temperature, we correlated MODIS albedo and monthly air temperature extracted from the ERA-Interim reanalysis dataset. Results show that decreasing trends exist with a strong spatial variability in the whole Alpine chain. In large glaciers, such as the Aletch (Swiss Alps), the trend varies significantly also within the glacier, showing that the trend is higher in the area across the accumulation and ablation zone. Over the 17 glaciers with mass balance available in the WGMS data set, 11 gave significant relationship with the MODIS summer albedo. Moreover, the comparison between ERA-Interim temperature

  18. Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

    Directory of Open Access Journals (Sweden)

    M. U. F. Kirschbaum

    2011-12-01

    Full Text Available Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, afforestation also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes.

    We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture albedo as 20 %. We used these data to calculate the direct radiative forcing effect of changing albedo as the forest grew.

    We calculated the radiative forcing resulting from the removal of carbon from the atmosphere as a decrease in radiative forcing of −104 GJ tC−1 yr−1. We also showed that the observed change in albedo constituted a direct radiative forcing of 2759 GJ ha−1 yr−1. Thus, following afforestation, 26.5 tC ha−1 needs to be stored in a growing forest to balance the increase in radiative forcing resulting from the observed albedo change. Measurements of tree biomass and albedo were used to estimate the net change in radiative forcing as the newly planted forest grew. Albedo and carbon-storage effects were of similar magnitude for the first four to five years after tree planting, but as the stand grew older, the carbon storage effect increasingly dominated. Averaged over the whole

  19. Growing season carries stronger contributions to albedo dynamics on the Tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Li Tian

    Full Text Available The Tibetan Plateau has experienced higher-than-global-average climate warming in recent decades, resulting in many significant changes in ecosystem structure and function. Among them is albedo, which bridges the causes and consequences of land surface processes and climate. The plateau is covered by snow/ice and vegetation in the non-growing season (nGS and growing season (GS, respectively. Based on the MODIS products, we investigated snow/ice cover and vegetation greenness in relation to the spatiotemporal changes of albedo on the Tibetan Plateau from 2000 through 2013. A synchronous relationship was found between the change in GSNDVI and GSalbedo over time and across the Tibetan landscapes. We found that the annual average albedo had a decreasing trend, but that the albedo had slightly increased during the nGS and decreased during the GS. Across the landscapes, the nGSalbedo fluctuated in a synchronous pattern with snow/ice cover. Temporally, monthly snow/ice coverage also had a high correspondence with albedo, except in April and October. We detected clear dependencies of albedo on elevation. With the rise in altitude, the nGSalbedo decreased below 4000 m, but increased for elevations of 4500-5500 m. Above 5500 m, the nGSalbedo decreased, which was in accordance with the decreased amount of snow/ice coverage and the increased soil moisture on the plateau. More importantly, the decreasing albedo in the most recent decade appeared to be caused primarily by lowered growing season albedo.

  20. Carbon storage versus albedo change: Radiative Forcing of forest expansion in temperate mountainous regions of Switzerland

    Science.gov (United States)

    Schwaab, J.; Bavay, M.; Davin, E.; Hagedorn, F.; Hüsler, F.; Lehning, M.; Schneebeli, M.; Thürig, E.; Bebi, P.

    2014-06-01

    Forestation is seen as a possible option to counter climate change by sequestering carbon in forests and thus reducing the atmospheric concentration of carbon dioxide. However, previous studies suggest that the Radiative Forcing (RF) caused by forestation-induced albedo change in snow-rich boreal regions may offset the carbon sequestration effect. The Swiss mountains are characterized by snow-rich areas with strongly varying environmental conditions and forest expansion is currently the dominant land-use change process. Thus, quantifying both carbon sequestration and albedo change on appropriately high resolution in this region will improve our understanding of the forests potential for climate mitigation. We calculated the albedo RF based on remotely sensed datasets of albedo, global radiation and snow cover. Carbon sequestration was estimated from changes in carbon stocks based on National Inventories. Our results show that the net RF of forest expansion ranges from -24 W m-2 at low elevations of the Northern Prealps to 2 W m-2 at high elevations of the Central Alps. The albedo RF increases with increasing altitude, which offsets the CO2 RF at high elevations with long snow-covered periods, high global radiation and low carbon sequestration. Results indicate that the albedo RF is particularly relevant during transitions from open land to open forest and not in later stages of forest development. The albedo RF offsets the CO2 RF by an average of 40% between 1985 and 1997 when overall forest expansion in Switzerland was approximately 4%. We conclude that the albedo RF should be considered at an appropriately high resolution when estimating the climatic effect of forestation in temperate mountainous regions.

  1. Search for the cause of the low albedo of the Moon

    International Nuclear Information System (INIS)

    Gold, T.; Bilson, E.; Baron, R.L.

    1975-01-01

    Experimentation concerning lunar weathering and its effect on the albedo of the surface cover consisted of determination of the surface chemical composition of lunar soil and ground-up rock samples by Auger electron spectroscopy, measurement of the optical albedo of these samples, and proton or alpha-particle irradiation of terrestrial rock chips and rock powders and of ground-up lunar rock samples in order to determine the optical and surface chemical effect of simulated solar wind

  2. Surface Albedo Darkening from wildfires in Northern Sub-Saharan Africa

    Science.gov (United States)

    Gatebe, C. K.; Ichoku, C. M.; Poudal, R.; Roman, M. O.; Wilcox, E.

    2014-01-01

    Wildfires are recognized as a key physical disturbance of terrestrial ecosystems and a major source of atmospheric trace gases and aerosols. They are known to produce changes in landscape patterns and lead to changes in surface albedo that can persist for long periods. Here, we estimate the darkening of surface albedo due to wildfires in different land cover ecosystems in the Northern Sub-Saharan Africa using data from the Moderate Resolution Imaging Spectroradiometer (MODIS). We determined a decrease in albedo after fires over most land cover types (e.g. woody savannas: (-0.00352 0.00003) and savannas: (- 0.003910.00003), which together accounted for >86% of the total MODIS fire count between 2003 and 2011). Grasslands had a higher value (-0.00454 0.00003) than the savannas, but accounted for only about 5% of the total fire count. A few other land cover types (e.g. Deciduous broad leaf: (0.00062 0.00015), and barren: 0.00027 0.00019), showed an increase in albedo after fires, but accounted for less than 1% of the total fires. Albedo change due to wildfires is more important during the fire season (October-February). The albedo recovery progresses rapidly during the first year after fires, where savannas show the greatest recovery (>77%) within one year, while deciduous broadleaf, permanent wetlands and barren lands show the least one-year recovery (56%). The persistence of surface albedo darkening in most land cover types is limited to about six to seven years, after which at least 98% of the burnt pixels recover to their pre-fire albedo.

  3. Albedo impact on the suitability of biochar systems to mitigate global warming.

    Science.gov (United States)

    Meyer, Sebastian; Bright, Ryan M; Fischer, Daniel; Schulz, Hardy; Glaser, Bruno

    2012-11-20

    Biochar application to agricultural soils can change the surface albedo which could counteract the climate mitigation benefit of biochar systems. However, the size of this impact has not yet been quantified. Based on empirical albedo measurements and literature data of arable soils mixed with biochar, a model for annual vegetation cover development based on satellite data and an assessment of the annual development of surface humidity, an average mean annual albedo reduction of 0.05 has been calculated for applying 30-32 Mg ha(-1) biochar on a test field near Bayreuth, Germany. The impact of biochar production and application on the carbon cycle and on the soil albedo was integrated into the greenhouse gas (GHG) balance of a modeled pyrolysis based biochar system via the computation of global warming potential (GWP) characterization factors. The analysis resulted in a reduction of the overall climate mitigation benefit of biochar systems by 13-22% due to the albedo change as compared to an analysis which disregards the albedo effect. Comparing the use of the same quantity of biomass in a biochar system to a bioenergy district heating system which replaces natural gas combustion, bioenergy heating systems achieve 99-119% of the climate benefit of biochar systems according to the model calculation.

  4. Enhanced albedo feedback in North Africa from possible combined vegetation and soil-formation processes

    Energy Technology Data Exchange (ETDEWEB)

    Knorr, Wolfgang [University of Bristol, Department of Earth Sciences, Bristol (United Kingdom); Schnitzler, Karl-Georg [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)

    2006-01-01

    It has long been recognized that albedo related vegetation feedbacks amplify climate variability in North Africa. Recent studies have revealed that areas of very high albedo associated with certain desert soil types contribute to the current dry climate of the region. We construct three scenarios of North African albedo, one based on satellite measurements, one where the highest albedo resembles that of soils in the desert transition zones, and one based on a vegetation map for the ''green Sahara'' state of the middle Holocene, ca. 6,000 years ago. Using a series of climate model simulations, we find that the additional amplitude of albedo change from the middle Holocene to the present caused by the very bright desert soils enhances the magnitude of the June-to-August precipitation change in the region of the present Sahara from 0.6 to 1.0 mm/day on average. We also find that albedo change has a larger effect on regional precipitation than changes in either the Earth's orbit or sea surface temperatures between 6,000 years ago and today. Simulated precipitation agrees rather well with present observations and mid Holocene reconstructions. Our results suggest that there may exist an important climate feedback from soil formation processes that has so far not been recognized. (orig.)

  5. Method to determine snow albedo values in the ultraviolet for radiative transfer modeling.

    Science.gov (United States)

    Schwander, H; Mayer, B; Ruggaber, A; Albold, A; Seckmeyer, G; Koepke, P

    1999-06-20

    For many cases modeled and measured UV global irradiances agree to within +/-5% for cloudless conditions, provided that all relevant parameters for describing the atmosphere and the surface are well known. However, for conditions with snow-covered surfaces this agreement is usually not achievable, because on the one hand the regional albedo, which has to be used in a model, is only rarely available and on the other hand UV irradiance alters with different snow cover of the surface by as much as 50%. Therefore a method is given to determine the regional albedo values for conditions with snow cover by use of a parameterization on the basis of snow depth and snow age, routinely monitored by the weather services. An algorithm is evolved by multiple linear regression between the snow data and snow-albedo values in the UV, which are determined from a best fit of modeled and measured UV irradiances for an alpine site in Europe. The resulting regional albedo values in the case of snow are in the 0.18-0.5 range. Since the constants of the regression depend on the area conditions, they have to be adapted if the method is applied for other sites. Using the algorithm for actual cases with different snow conditions improves the accuracy of modeled UV irradiances considerably. Compared with the use of an average, constant snow albedo, the use of actual albedo values, provided by the algorithm, halves the average deviations between measured and modeled UV global irradiances.

  6. CLARA-SAL: a global 28 yr timeseries of Earth's black-sky surface albedo

    Directory of Open Access Journals (Sweden)

    A. Riihelä

    2013-04-01

    Full Text Available We present a novel 28 yr dataset of Earth's black-sky surface albedo, derived from AVHRR instruments. The dataset is created using algorithms to separately derive the surface albedo for different land use areas globally. Snow, sea ice, open water and vegetation are all treated independently. The product features corrections for the atmospheric effect in satellite-observed surface radiances, a BRDF correction for the anisotropic reflectance properties of natural surfaces, and a novel topography correction of geolocation and radiometric accuracy of surface reflectance observations over mountainous areas. The dataset is based on a homogenized AVHRR radiance timeseries. The product is validated against quality-controlled in situ observations of clear-sky surface albedo at various BSRN sites around the world. Snow and ice albedo retrieval validation is given particular attention using BSRN sites over Antarctica, Greenland Climate Network stations on the Greenland Ice Sheet (GrIS, as well as sea ice albedo data from the SHEBA and Tara expeditions. The product quality is found to be comparable to other previous long-term surface albedo datasets from AVHRR.

  7. Retrieval of snow albedo and grain size using reflectance measurements in Himalayan basin

    Directory of Open Access Journals (Sweden)

    H. S. Negi

    2011-03-01

    Full Text Available In the present paper, spectral reflectance measurements of Himalayan seasonal snow were carried out and analysed to retrieve the snow albedo and effective grain size. The asymptotic radiative transfer (ART theory was applied to retrieve the plane and spherical albedo. The retrieved plane albedo was compared with the measured spectral albedo and a good agreement was observed with ±10% differences. Retrieved integrated albedo was found within ±6% difference with ground observed broadband albedo. The retrieved snow grain sizes using different models based on the ART theory were compared for various snow types and it was observed that the grain size model using two channel method (one in visible and another in NIR region can work well for the Himalayan seasonal snow and it was found consistent with temporal changes in grain size. This method can work very well for clean, dry snow as in the upper Himalaya, but sometimes, due to the low reflectances (<20% using wavelength 1.24 μm, the ART theory cannot be applied, which is common in lower and middle Himalayan old snow. This study is important for monitoring the Himalayan cryosphere using air-borne or space-borne sensors.

  8. Thermal properties of poly(ethylene oxide)/lauric acid blends. A SSA-DSC study

    Energy Technology Data Exchange (ETDEWEB)

    Pielichowski, Krzysztof; Flejtuch, Kinga [Department of Chemistry and Technology of Polymers, Cracow University of Technology, ul. Warszawska 24, 31-155 Krakow (Poland)

    2006-03-15

    A series of poly(ethylene oxide) (PEO)/lauric acid blends with different compositions has been prepared and characterised by differential scanning calorimetry (DSC) in dynamic mode. It has been found that the enthalpy of melting and crystallisation reaches its highest value for PEO/lauric acid blend (1:1, w/w) which makes this system a promising candidate for thermal energy storage applications. Further studies by step-scan alternating (SSA)-DSC revealed that an increase of the temperature step causes that the average total heating rate is also increasing and the heat flow is characterised by higher values. Reversing component of the heat flow during melting reaches lowest values at highest step (step=1{sup o}) when the re-crystallisation of PEO is hindered. An increase of step generally leads to an increase of the number of non-equilibrium effects and facilitates the activation of kinetic non-reversing processes, hindering the overall crystallisation of PEO. For lauric acid, due to facile crystallisation and self-association, formation of ordered regular structures takes place faster and is influenced by non-reversing processes in higher proportion. (author)

  9. SPITZER OBSERVATIONS OF EXTENDED LYMAN-α CLOUDS IN THE SSA22 FIELD

    International Nuclear Information System (INIS)

    Webb, T. M. A.; Gonzalez, M.; Yamada, T.; Huang, J.-S.; Ashby, M. L. N; Matsuda, Y.; Egami, E.; Hayashimo, T.

    2009-01-01

    We present the results of a Spitzer IRAC and MIPS 24 μm study of extended Lyman-α clouds (or Lyman-α Blobs, LABs) within the SSA22 filamentary structure at z = 3.09. We detect 6/26 LABs in all IRAC filters, four of which are also detected at 24 μm, and find good correspondence with the 850 μm measurements of Geach et al. An analysis of the rest-frame ultraviolet, optical, near- and mid-infrared colors reveals that these six systems exhibit signs of nuclear activity (active galactic nucleus (AGN)) and/or extreme star formation. Notably, they have properties that bridge galaxies dominated by star formation (Lyman-break galaxies (LBGs)) and those with AGNs (LBGs classified as QSOs). The LAB systems not detected in all four IRAC bands, on the other hand, are, as a group, consistent with pure star-forming systems, similar to the majority of the LBGs within the filament. These results indicate that the galaxies within LABs do not comprise a homogeneous population, though they are also consistent with scenarios in which the gas halos are ionized through a common mechanism such as galaxy-scale winds driven by the galaxies within them, or gravitational heating of the collapsing cloud itself.

  10. Benefits of Applying Predictive Intelligence to the Space Situational Awareness (SSA) Mission

    Science.gov (United States)

    Lane, B.; Mann, B.; Millard, C.

    Recent events have heightened the interest in providing improved Space Situational Awareness (SSA) to the warfighter using novel techniques that are affordable and effective. The current Space Surveillance Network (SSN) detects, tracks, catalogs and identifies artificial objects orbiting earth and provides information on Resident Space Objects (RSO) as well as new foreign launch (NFL) satellites. The reactive nature of the SSN provides little to no warning on changes to the expected states of these RSOs or NFLs. This paper will detail the use of the historical data collected on RSOs to characterize what their steady state is, proactively help identify when changes or anomalies have occurred using a pattern-of-like activity based intelligence approach, and apply dynamic, adaptive mission planning to the observables that lead up to a NFL. Multiple hypotheses will be carried along with the intent or the changes to the steady state to assist the SSN in tasking the various sensors in the network to collect the relevant data needed to help prune the number of hypotheses by assigning likelihood to each of those activities. Depending on the hypothesis and thresholds set, these likelihoods will then be used in turn to alert the SSN operator with changes to the steady state, prioritize additional data collections, and provide a watch list of likely next activities.

  11. Ro/SSA autoantibodies directly bind cardiomyocytes, disturb calcium homeostasis, and mediate congenital heart block.

    Science.gov (United States)

    Salomonsson, Stina; Sonesson, Sven-Erik; Ottosson, Lars; Muhallab, Saad; Olsson, Tomas; Sunnerhagen, Maria; Kuchroo, Vijay K; Thorén, Peter; Herlenius, Eric; Wahren-Herlenius, Marie

    2005-01-03

    Congenital heart block develops in fetuses after placental transfer of Ro/SSA autoantibodies from rheumatic mothers. The condition is often fatal and the majority of live-born children require a pacemaker at an early age. The specific antibody that induces the heart block and the mechanism by which it mediates the pathogenic effect have not been elucidated. In this study, we define the cellular mechanism leading to the disease and show that maternal autoantibodies directed to a specific epitope within the leucine zipper amino acid sequence 200-239 (p200) of the Ro52 protein correlate with prolongation of fetal atrioventricular (AV) time and heart block. This finding was further confirmed experimentally in that pups born to rats immunized with p200 peptide developed AV block. p200-specific autoantibodies cloned from patients bound cultured cardiomyocytes and severely affected Ca2+ oscillations, leading to accumulating levels and overload of intracellular Ca2+ levels with subsequent loss of contractility and ultimately apoptosis. These findings suggest that passive transfer of maternal p200 autoantibodies causes congenital heart block by dysregulating Ca2+ homeostasis and inducing death in affected cells.

  12. Are crude oil markets multifractal? Evidence from MF-DFA and MF-SSA perspectives

    Science.gov (United States)

    He, Ling-Yun; Chen, Shu-Peng

    2010-08-01

    In this article, we investigated the multifractality and its underlying formation mechanisms in international crude oil markets, namely, Brent and WTI, which are the most important oil pricing benchmarks globally. We attempt to find the answers to the following questions: (1) Are those different markets multifractal? (2) What are the dynamical causes for multifractality in those markets (if any)? To answer these questions, we applied both multifractal detrended fluctuation analysis (MF-DFA) and multifractal singular spectrum analysis (MF-SSA) based on the partition function, two widely used multifractality detecting methods. We found that both markets exhibit multifractal properties by means of these methods. Furthermore, in order to identify the underlying formation mechanisms of multifractal features, we destroyed the underlying nonlinear temporal correlation by shuffling the original time series; thus, we identified that the causes of the multifractality are influenced mainly by a nonlinear temporal correlation mechanism instead of a non-Gaussian distribution. At last, by tracking the evolution of left- and right-half multifractal spectra, we found that the dynamics of the large price fluctuations is significantly different from that of the small ones. Our main contribution is that we not only provided empirical evidence of the existence of multifractality in the markets, but also the sources of multifractality and plausible explanations to current literature; furthermore, we investigated the different dynamical price behaviors influenced by large and small price fluctuations.

  13. Anti-Ro52 antibody level is an important marker of fetal congenital heart block risk in anti-Ro/SSA antibody positive pregnancy.

    Science.gov (United States)

    Miyasato-Isoda, Mai; Waguri, Masako; Yamada, Yuko; Miyano, Akira; Wada, Yoshinao

    2017-09-21

    The aims of this study are to determine the incidence of congenital heart block (CHB) in the Japanese population and identify maternal factors predicting fetal CHB in anti-Ro/SSA antibody positive pregnancy. A retrospective study was performed using 52,147 clinical records of pregnancies followed in a single center. For 183 anti-Ro/SSA antibody-positive women, anti-Ro52 and Ro60 antibodies were measured, and the odds of CHB in relation to maternal clinical features were calculated by multivariate analysis. The receiver-operating characteristic (ROC) curves for predicting CHB were constructed for the titers of anti-Ro/SSA, anti-Ro52 and anti-Ro60 antibodies. Fetal CHB occurred in two pregnancies among those without known risks such as positive anti-Ro/SSA antibody or previous CHB-affected pregnancy, suggesting an incidence similar to that in Caucasian populations. As for the anti-Ro/SSA antibody positive pregnancies, the titers of anti-Ro/SSA, anti-Ro52 and anti-Ro60 antibodies were independent risk factors for fetal CHB and the use of corticosteroids before 18 gestational weeks was an independent protective factor. The area under the ROC was 0.84, 0.73 and 0.74 for anti-Ro52, anti-Ro60 and anti-Ro/SSA antibodies, respectively. CHB occurred in two among approximately 50,000 pregnancies without known risks such as positive anti-Ro/SSA antibody or previous delivery of CHB-affected babies. Measurement of anti-Ro52 antibody levels may be helpful in extracting a risk group of delivering CHB infants in the anti-Ro/SSA antibody positive pregnancy.

  14. The Alpine snow-albedo feedback in regional climate models

    Science.gov (United States)

    Winter, Kevin J.-P. M.; Kotlarski, Sven; Scherrer, Simon C.; Schär, Christoph

    2017-02-01

    The effect of the snow-albedo feedback (SAF) on 2m temperatures and their future changes in the European Alps is investigated in the ENSEMBLES regional climate models (RCMs) with a focus on the spring season. A total of 14 re-analysis-driven RCM experiments covering the period 1961-2000 and 10 GCM-driven transient climate change projections for 1950-2099 are analysed. A positive springtime SAF is found in all RCMs, but the range of the diagnosed SAF is large. Results are compared against an observation-based SAF estimate. For some RCMs, values very close to this estimate are found; other models show a considerable overestimation of the SAF. Net shortwave radiation has the largest influence of all components of the energy balance on the diagnosed SAF and can partly explain its spatial variability. Model deficiencies in reproducing 2m temperatures above snow and ice and associated cold temperature biases at high elevations seem to contribute to a SAF overestimation in several RCMs. The diagnosed SAF in the observational period strongly influences the estimated SAF contribution to twenty first century temperature changes in the European Alps. This contribution is subject to a clear elevation dependency that is governed by the elevation-dependent change in the number of snow days. Elevations of maximum SAF contribution range from 1500 to 2000 m in spring and are found above 2000 m in summer. Here, a SAF contribution to the total simulated temperature change between 0 and 0.5 °C until 2099 (multi-model mean in spring: 0.26 °C) or 0 and 14 % (multi-model mean in spring: 8 %) is obtained for models showing a realistic SAF. These numbers represent a well-funded but only approximate estimate of the SAF contribution to future warming, and a remaining contribution of model-specific SAF misrepresentations cannot be ruled out.

  15. The potential impacts of climate change induced changes to tropical leaf albedo and its feedback on global climate

    Science.gov (United States)

    Doughty, C.; Shenkin, A.; Bentley, L. P.; Malhi, Y.

    2017-12-01

    Tropical forest leaf albedo plays a critical role in global climate by determining how much radiation the planet absorbs near the equator. However, little is known about how tropical leaf albedo could be affected by climate change and how any such changes in albedo could, in turn, impact global climate. Here we measure sunlit leaf albedo along two elevation temperature gradients (a 3000-meter gradient in Peru (10 plots) and a 1500 m gradient in Australia (10 plots) and along two wet to dry transects (a 2000 mm yr-1 gradient in Ghana (10 plots) and a 2000 mm yr-1 gradient in Brazil (10 plots). We found a highly significant increase in visible leaf albedo with wetness at both wet to dry gradients. We also found a marginally significant trend of increased albedo with warmer temperatures along one of the elevation gradients. Leaf albedo can also be impacted by changes in species composition, variations in interspecific variation, and changes in leaf chlorophyll concentrations. We removed the dominant two species from the basal area weighting for each plots but found no significant change, a directional change of interspecific variation could change albedo by 0.01 in the NIR, and changes in chlorophyll could decrease visible albedo by 0.005. We then simulated changes in tropical leaf albedo with a climate model and show that such changes could act as a small negative feedback on climate, but most likely will not have a large impact on future climate.

  16. Kinetic and isotherm studies of bisphenol A adsorption onto orange albedo(Citrus sinensis): Sorption mechanisms based on the main albedo components vitamin C, flavones glycosides and carotenoids.

    Science.gov (United States)

    Kamgaing, Theophile; Doungmo, Giscard; Melataguia Tchieno, Francis Merlin; Gouoko Kouonang, Jimmy Julio; Mbadcam, Ketcha Joseph

    2017-07-03

    Orange albedo and its adsorption capacity towards bisphenol A (BPA) were studied. Adsorption experiments were conducted in batch mode at 25-55°C. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the biosorbent. The effects of various parameters including adsorption time, equilibrium pH, adsorbent dosage and initial adsorbate concentration were investigated. The optimum contact time and pH for the removal of BPA were 60 min and 2, respectively. It was found that the adsorption isotherms best matched the Freundlich model, the adsorption of BPA being multilayer and that of the albedo surface heterogeneous. From the kinetic studies, it was found that the removal of BPA best matched the pseudo-second order kinetic model. An adsorption mechanism based on the albedo surface molecules is proposed and gives a good account of π-π interactions and hydrogen bonding. Orange albedo, with a maximum BPA loading capacity of 82.36 mg g -1 (significantly higher than that of most agricultural residues), is a good candidate for BPA adsorption in aqueous media.

  17. Development in neutron dosimetry: automatic traces reading system and albedo OSL dosimetry; Developpement en dosimetrie neutron: systeme automatique de lecture de traces et dosimetrie albedo OSL

    Energy Technology Data Exchange (ETDEWEB)

    Million, M.; Perks, C.A.; Faugoin, S.; Archambault, V. [LCIE Landauer, 92 - Fontenay aux Roses (France)

    2009-07-01

    To answer to a regulatory evolution and technical constraints, the Landauer group introduced on the make an automatic reading system of neutron traces and an albedo dosemeter based on the O.S.L. in light dosemeters (O.S.L. for optically stimulated luminescence). In this article are described the last developments in matter of neutron dosimetry. (N.C.)

  18. 30-m Land Surface Albedo by Integrating Landsat directional reflectance and MODIS anisotropic information

    Science.gov (United States)

    Shuai, Y.; Masek, J. G.; Gao, F.; Schaaf, C.; Williams, C. A.; Wang, Z.

    2012-12-01

    Land surface albedo as a key physical variable determining the solar energy absorbed by the land surface, and can affect climate through ecosystem feedback processes. Some studies have highlighted that positive radiative forcing (warming) induced by increased forest cover and decreased albedo in temperate and boreal forest regions could offset the negative forcing expected from carbon sequestration (Betts 2000). However, these studies have not used data at the spatial resolution of human land dynamics (e.g. 30m Landsat resolution). Therefore, there is a need for improved estimates of land surface albedo at high resolution to fully understand the role of land cover change in climate forcing and carbon cycle. Following our initial "concurrent" approach applied to Landsat data acquired during the post-2000 MODIS era (Shuai et al.2011), we have developed a "pre-MODIS era" approach to generate 30-meter albedos using Landsat surface directional reflectance (1970s-2000) and Look-Up-Tables (LUT) of anisotropy information extracted from MODIS BRDF data. We use a NLCD (National Land Cover Dataset)-class-based LUT for non-disturbed land cover. Disturbed forest patches are identified from the Monitoring Trends in Burn Severity (MTBS) and North American Forest Dynamics (NAFD) datasets. For each category, high quality MODIS BRDF parameters (MCD43A1 product) are retrieved and used to populate the LUT. Each entry in the LUT reflects a unique combination of land cover type, disturbance age and type, season/month, and sensor bands. The initial BRDF LUT generated for the Pacific Northwest of the United States exhibits various BRDF evolution trajectories for disturbed classes, including different recovery trajectories for fire and non-fire disturbance. The albedo-to-nadir-ratio method (Shuai et al., 2011) is applied to the BRDF LUT to calculate spectral albedos, followed by a narrow-to-broadband conversion (Liang 2000) to generate broad-band shortwave albedo. Our preliminary

  19. Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets

    Energy Technology Data Exchange (ETDEWEB)

    Menon, Surabi; Akbari, Hashem; Mahanama, Sarith; Sednev, Igor; Levinson, Ronnen

    2010-02-12

    The two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present-day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and land surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe by 0.1. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the change in the total outgoing (outgoing shortwave+longwave) radiation and land surface temperature to a 0.1 increase in urban albedos for all global land areas. The global average increase in the total outgoing radiation was 0.5 Wm{sup -2}, and temperature decreased by {approx}0.008 K for an average 0.003 increase in surface albedo. These averages represent all global land areas where data were available from the land surface model used and are for the boreal summer (June-July-August). For the continental U.S. the total outgoing radiation increased by 2.3 Wm{sup -2}, and land surface temperature decreased by {approx}0.03 K for an average 0.01 increase in surface albedo. Based on these forcings, the expected emitted CO{sub 2} offset for a plausible 0.25 and 0.15 increase in albedos of roofs and pavements, respectively, for all global urban areas, was found to be {approx} 57 Gt CO{sub 2}. A more meaningful evaluation of the impacts of urban albedo increases on global climate and the expected CO{sub 2} offsets would require simulations which better characterizes urban surfaces and represents the full annual cycle.

  20. Pectins from the albedo of immature lemon fruitlets have high water binding capacity.

    Science.gov (United States)

    Schröder, Roswitha; Clark, Christopher J; Sharrock, Keith; Hallett, Ian C; MacRae, Elspeth A

    2004-04-01

    The white part of citrus peel, the albedo, has a special role in water relations of both fruit and leaves from early on in fruit development. In times of drought, this tissue acts as a water reservoir for juice sacs, seeds and leaves. When water was injected into the albedo, free water was undetectable using magnetic resonance imaging. Microscopy showed tightly packed cells with little intercellular space, and thick cell walls. Cell wall material comprised 21% of the fresh albedo weight, and contained 26.1% galacturonic acid, the main constituent of pectin. From this, we postulated that pectin of the cell wall was responsible for the high water-binding capacity of the immature lemon albedo. Cell wall material was extracted using mild procedures that keep polymers intact, and four pectic fractions were recovered. Of these fractions, the SDS and chelator-soluble fractions showed viscosities ten and twenty times higher than laboratory-grade citrus pectin or the other albedo-derived pectins. The yield of these two pectins represented 28% of the cell walls and 62% of the galacturonic acid content of immature lemon albedo. We concluded that, from viscosity and abundance, these types of pectin account for the high water-binding capacity of this tissue. Compositional analyses showed that the two highly viscous pectic fractions differ in galacturonic acid content, degree of branching and length of side chains from the less viscous albedo-derived pectins. The most striking feature of these highly viscous pectins, however, was their high molecular weight distribution compared to the other pectic fractions.

  1. Spatiotemporal variation of surface shortwave forcing from fire-induced albedo change in interior Alaska

    Science.gov (United States)

    Huang, Shengli; Dahal, Devendra; Liu, Heping; Jin, Suming; Young, Claudia J.; Liu, Shuang; Liu, Shu-Guang

    2015-01-01

    The albedo change caused by both fires and subsequent succession is spatially heterogeneous, leading to the need to assess the spatiotemporal variation of surface shortwave forcing (SSF) as a component to quantify the climate impacts of high-latitude fires. We used an image reconstruction approach to compare postfire albedo with the albedo assuming fires had not occurred. Combining the fire-caused albedo change from the 2001-2010 fires in interior Alaska and the monthly surface incoming solar radiation, we examined the spatiotemporal variation of SSF in the early successional stage of around 10 years. Our results showed that while postfire albedo generally increased in fall, winter, and spring, some burned areas could show an albedo decrease during these seasons. In summer, the albedo increased for several years and then declined again. The spring SSF distribution did not show a latitudinal decrease from south to north as previously reported. The results also indicated that although the SSF is usually largely negative in the early successional years, it may not be significant during the first postfire year. The annual 2005-2010 SSF for the 2004 fire scars was -1.30, -4.40, -3.31, -4.00, -3.42, and -2.47 Wm-2. The integrated annual SSF map showed significant spatial variation with a mean of -3.15 Wm-2 and a standard deviation of 3.26 Wm-2, 16% of burned areas having positive SSF. Our results suggest that boreal deciduous fires would be less positive for climate change than boreal evergreen fires. Future research is needed to comprehensively investigate the spatiotemporal radiative and non-radiative forcings to determine the effect of boreal fires on climate.

  2. Sea ice roughness: the key for predicting Arctic summer ice albedo

    Science.gov (United States)

    Landy, J.; Ehn, J. K.; Tsamados, M.; Stroeve, J.; Barber, D. G.

    2017-12-01

    Although melt ponds on Arctic sea ice evolve in stages, ice with smoother surface topography typically allows the pond water to spread over a wider area, reducing the ice-albedo and accelerating further melt. Building on this theory, we simulated the distribution of meltwater on a range of statistically-derived topographies to develop a quantitative relationship between premelt sea ice surface roughness and summer ice albedo. Our method, previously applied to ICESat observations of the end-of-winter sea ice roughness, could account for 85% of the variance in AVHRR observations of the summer ice-albedo [Landy et al., 2015]. Consequently, an Arctic-wide reduction in sea ice roughness over the ICESat operational period (from 2003 to 2008) explained a drop in ice-albedo that resulted in a 16% increase in solar heat input to the sea ice cover. Here we will review this work and present new research linking pre-melt sea ice surface roughness observations from Cryosat-2 to summer sea ice albedo over the past six years, examining the potential of winter roughness as a significant new source of sea ice predictability. We will further evaluate the possibility for high-resolution (kilometre-scale) forecasts of summer sea ice albedo from waveform-level Cryosat-2 roughness data in the landfast sea ice zone of the Canadian Arctic. Landy, J. C., J. K. Ehn, and D. G. Barber (2015), Albedo feedback enhanced by smoother Arctic sea ice, Geophys. Res. Lett., 42, 10,714-10,720, doi:10.1002/2015GL066712.

  3. Automatic, Rapid Replanning of Satellite Operations for Space Situational Awareness (SSA)

    Science.gov (United States)

    Stottler, D.; Mahan, K.

    An important component of Space Situational Awareness (SSA) is knowledge of the status and tasking of blue forces (e.g. satellites and ground stations) and the rapid determination of the impacts of real or hypothetical changes and the ability to quickly replan based on those changes. For example, if an antenna goes down (either for benign reasons or from purposeful interference) determining which missions will be impacted is important. It is not simply the set of missions that were scheduled to utilize that antenna, because highly expert human schedulers will respond to the outage by intelligently replanning the real-time schedule. We have developed an automatic scheduling and deconfliction engine, called MIDAS (for Managed Intelligent Deconfliction And Scheduling) that interfaces to the current legacy system (ESD 2.7) which can perform this replanning function automatically. In addition to determining the impact of failed resources, MIDAS can also replan in response to a satellite under attack. In this situation, additional supports must be quickly scheduled and executed (while minimizing impacts to other missions). Because MIDAS is a fully automatic system, replacing a current human labor-intensive process, and provides very rapid turnaround (seconds) it can also be used by commanders to consider what-if questions and focus limited protection resources on the most critical resources. For example, the commander can determine the impact of a successful attack on one of two ground stations and place heavier emphasis on protecting the station whose loss would create the most severe impacts. The system is currently transitioning to operational use. The MIDAS system and its interface to the legacy ESD 2.7 system will be described along with the ConOps for different types of detailed operational scenarios.

  4. SsaA, a Member of a Novel Class of Transcriptional Regulators, Controls Sansanmycin Production in Streptomyces sp. Strain SS through a Feedback Mechanism

    Science.gov (United States)

    Li, Qinglian; Wang, Lifei; Xie, Yunying; Wang, Songmei; Chen, Ruxian

    2013-01-01

    Sansanmycins, produced by Streptomyces sp. strain SS, are uridyl peptide antibiotics with activities against Pseudomonas aeruginosa and multidrug-resistant Mycobacterium tuberculosis. In this work, the biosynthetic gene cluster of sansanmycins, comprised of 25 open reading frames (ORFs) showing considerable amino acid sequence identity to those of the pacidamycin and napsamycin gene cluster, was identified. SsaA, the archetype of a novel class of transcriptional regulators, was characterized in the sansanmycin gene cluster, with an N-terminal fork head-associated (FHA) domain and a C-terminal LuxR-type helix-turn-helix (HTH) motif. The disruption of ssaA abolished sansanmycin production, as well as the expression of the structural genes for sansanmycin biosynthesis, indicating that SsaA is a pivotal activator for sansanmycin biosynthesis. SsaA was proved to directly bind several putative promoter regions of biosynthetic genes, and comparison of sequences of the binding sites allowed the identification of a consensus SsaA binding sequence, GTMCTGACAN2TGTCAGKAC. The DNA binding activity of SsaA was inhibited by sansanmycins A and H in a concentration-dependent manner. Furthermore, sansanmycins A and H were found to directly interact with SsaA. These results indicated that SsaA strictly controls the production of sansanmycins at the transcriptional level in a feedback regulatory mechanism by sensing the accumulation of the end products. As the first characterized regulator of uridyl peptide antibiotic biosynthesis, the understanding of this autoregulatory process involved in sansanmycin biosynthesis will likely provide an effective strategy for rational improvements in the yields of these uridyl peptide antibiotics. PMID:23475969

  5. Early Student Support to Investigate the Role of Sea Ice-Albedo Feedback in Sea Ice Predictions

    Science.gov (United States)

    2014-09-30

    Ice - Albedo Feedback in Sea Ice Predictions Cecilia M. Bitz Atmospheric Sciences MS351640 University of Washington Seattle, WA 98196-1640 phone...TERM GOALS The overarching goals of this project are to understand the role of sea ice - albedo feedback on sea ice predictability, to improve how...sea- ice albedo is modeled and how sea ice predictions are initialized, and then to evaluate how these improvements influence inherent sea ice

  6. Constraining MODIS snow albedo at large solar zenith angles: Implications for the surface energy budget in Greenland

    OpenAIRE

    Wang, Xianwei; Zender, Charles S

    2010-01-01

    An understanding of the surface albedo of high latitudes is crucial for climate change studies. MODIS albedo retrievals flagged as high-quality compare well with in situ Greenland Climate Network (GC-Net) measurements but cover too small an area to fully characterize Greenland's albedo in nonsummer months. In contrast, poor quality MODIS retrievals provide adequate spatiotemporal coverage, but are not recommended for use at large solar zenith angles (SZAs) where they have a systematic low bia...

  7. MODIS snow albedo bias at high solar zenith angles relative to theory and to in situ observations in Greenland

    OpenAIRE

    Wang, Xianwei; Zender, Charles S

    2010-01-01

    In situ measurements of snow albedo at five stations along a north–south transect in the dry-snow facies of the interior of Greenland follow the theoretically expected dependence of snow albedo with solar zenith angle (SZA). Greenland Climate Network (GC-Net) measurements from 1997 through 2007 exhibit the trend of modest surface brightening with increasing SZA on both diurnal and seasonal timescales. SZA explains up to 50% of seasonal albedo variability. The two other environmental factors c...

  8. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

    Directory of Open Access Journals (Sweden)

    J. Delamere

    2011-09-01

    Full Text Available 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.

  9. Bipolar high temporal resolution measurements of snow UV albedo in Sodankylä and Marambio

    Science.gov (United States)

    Meinander, Outi; Kontu, Anna; Asmi, Eija; Sanchez, Ricardo; Mei, Miguel; de Leeuw, Gerrit

    2015-04-01

    In this presentation we will give an overview of our high temporal resolution polar snow UV albedo data from Arctic Sodankylä, and from Marambio, Antarctica. These both are WMO GAW stations with many measurement parameters relevant to the albedo data usage. We will also describe our campaign based polar albedo data (SNORTEX and SOS campaigns), and an important data set of light absorbing impurities (BC) in the Arctic snow. The black carbon (BC) has been estimated to be the second most important human emission after carbon dioxide, in terms of its climate forcing in the present-day atmosphere. The reflectance effect of BC deposited on snow surface is the bigger the smaller the wavelength, i.e. the albedo effect of BC is the biggest at UV. This is also shown in SNICAR-model simulated albedo values. In Sodankylä, our bipolar snow ultraviolet (UV) albedo research started within the International Polar Year (IPY) 2007-2008. In 2007, the continuous Sodankylä snow UV albedo measurements were installed in Sodankylä, in the operational albedo field of the Finnish Meteorological Institute Arctic Research Center (FMI-ARC). These Sodankylä 1-min data during snow time were soon compared with the German Antarctic Neumayer Station UV albedo data, also with the same sensor type. In both data we found an up to 10 % decrease in albedo as a function of time within a day, ranging from 0.77 to 0.67 in Sodankylä and from 0.96 to 0.86 in Neumeyer. Physical explanations to asymmetry were found for cases with high relative humidity and low surface temperature during the previous night, favorable to frost and higher albedo on the next morning; new snow on the previous night; snow melting during day time and refreezing during night. In Marambio, in the beginning of 2013, our new continuous Finnish-Argentinian co-operation snow UV albedo measurements were installed and started as part of a larger continuous meteorological and environmental instrumentation. These new UV radiation data

  10. Change in Urban Albedo in London: A Multi-scale Perspective

    Science.gov (United States)

    Susca, T.; Kotthaus, S.; Grimmond, S.

    2013-12-01

    Urbanization-induced change in land use has considerable implications for climate, air quality, resources and ecosystems. Urban-induced warming is one of the most well-known impacts. This directly and indirectly can extend beyond the city. One way to reduce the size of this is to modify the surface atmosphere exchanges through changing the urban albedo. As increased rugosity caused by the morphology of a city results in lower albedo with constant material characteristics, the impacts of changing the albedo has impacts across a range of scales. Here a multi-scale assessment of the potential effects of the increase in albedo in London is presented. This includes modeling at the global and meso-scale informed by local and micro-scale measurements. In this study the first order calculations are conducted for the impact of changing the albedo (e.g. a 0.01 increase) on the radiative exchange. For example, when incoming solar radiation and cloud cover are considered, based on data retrieved from NASA (http://power.larc.nasa.gov/) for ~1600 km2 area of London, would produce a mean decrease in the instantaneous solar radiative forcing on the same surface of 0.40 W m-2. The nature of the surface is critical in terms of considering the impact of changes in albedo. For example, in the Central Activity Zone in London pavement and building can vary from 10 to 100% of the plan area. From observations the albedo is seen to change dramatically with changes in building materials. For example, glass surfaces which are being used increasingly in the central business district results in dramatic changes in albedo. Using the documented albedo variations determined across different scales the impacts are considered. For example, the effect of the increase in urban albedo is translated into the corresponding amount of avoided emission of carbon dioxide that produces the same effect on climate. At local scale, the effect that the increase in urban albedo can potentially have on local

  11. A minimal, statistical model for the surface albedo of Vestfonna ice cap, Svalbard

    Directory of Open Access Journals (Sweden)

    M. Möller

    2012-09-01

    Full Text Available The ice cap Vestfonna is located in northeastern Svalbard and forms one of the largest ice bodies of the Eurasian Arctic. Its surface albedo plays a key role in the understanding and modelling of its energy and mass balance. The principle governing factors for albedo evolution, i.e. precipitation and air temperature and therewith snow depth and melt duration, were found to vary almost exclusively with terrain elevation throughout the ice cap. Hence, surface albedo can be expected to develop a comparable pattern. A new statistical model is presented that estimates this mean altitudinal albedo profile of the ice cap on the basis of a minimal set of meteorological variables on a monthly resolution. Model calculations are based on a sigmoid function of the artificial quantity rain-snow ratio and a linear function of cumulative snowfall and cumulative positive degree days. Surface albedo fields of the MODIS snow product MOD10A1 from the period March to October in the years 2001–2008 serve as a basis for both calibration and cross-validation of the model. The meteorological model input covers the period September 2000 until October 2008 and is based on ERA-Interim data of a grid point located close to the ice cap. The albedo model shows a good performance. The root mean square error between observed and modelled albedo values along the altitudinal profile is 0.057±0.028 (mean ± one standard deviation. The area weighted mean even reduces to a value of 0.054. Distinctly higher deviations (0.07–0.09 are only present throughout the very lowest and uppermost parts of the ice cap that are either small in area or hardly affected by surface melt. Thus, the new, minimal, statistical albedo model presented in this study is found to reproduce the albedo evolution on Vestfonna ice cap on a high level of accuracy and is thus suggested to be fully suitable for further application in broader energy or mass-balance studies of the ice cap.

  12. Albedo observation of near Earth C-type asteroid by Hayabusa2 LIDAR

    Science.gov (United States)

    Yamada, R.; Senshu, H.; Namiki, N.; Mizuno, T.; Noda, H.; Asari, K.; Yoshida, F.; Abe, S.; Oshigami, S.; Hirata, N.; Ishihara, Y.; Matsumoto, K.

    2016-12-01

    The Japanese asteroid explorer Hayabusa2 was launched at the end of 2014. Hayabusa2 is supposed to observe the near-Earth C-type asteroid 162173 Ryugu and bring surface material samples back to Earth in 2020. Hayabusa2 has the laser altimeter (LIDAR) for laser ranging. The LIDAR also has the function of measuring the intensities of a transmitted laser pulse and received pulse. We will apply these data to estimate the distribution of the normal albedo of Ryugu at a laser wavelength of 1.064 μm. The albedo variations on C-type asteroid was not found from previous exploration; NEAR Shoemaker due to observation at far distance (1200 km) during short term (40 min). Hayabusa2 will continue the observation at an altitude of 20km over a year and a half, and the albedo observation using the LIDAR will give first detailed information about normal albedo variation at 1.064 μm on C-type asteroid. In this presentation, we firstly describe a method used to estimate the normal albedo from the LIDAR data and the error. The intensities of the transmitted and received laser pulses are recorded by the LIDAR as digital power values. Therefore, we have determined the transfer functions of the laser module and receiver to convert these digital values into the pulse energies. The ratio of energy transmitted into the field of view of the LIDAR telescope to the total energy (the utilization ratio) has been also investigated to estimate received pulse energies. Then, we have evaluated the contribution of the errors of transfer functions and the utilization ratio to the normal albedo uncertainty. It has been found that the error of normal albedo will be 18.0 % at a nominal altitude of 20 km if the effects of the asteroid surface slope and roughness on the received pulse are accurately corrected. On the other hand, we don't have knowledges about how the albedo on C-type asteroid vary due to space weathering and aqueous alternation at observation condition of the LIDAR (1.064 μm and 0

  13. Expressive Single Scattering for Light Shaft Stylization

    NARCIS (Netherlands)

    Kol, T.R.; Klehm, O.; Seidel, Hans-Peter; Eisemann, E.

    2017-01-01

    Light scattering in participating media is a natural phenomenon that is increasingly featured in movies and games, as it is visually pleasing and lends realism to a scene. In art, it may further be used to express a certain mood or emphasize objects. Here, artists often rely on stylization when

  14. The SSB-positive/SSA-negative antibody profile is not associated with key phenotypic features of Sjögren's syndrome

    DEFF Research Database (Denmark)

    Baer, Alan N; McAdams DeMarco, Mara; Shiboski, Stephen C

    2015-01-01

    phenotypic features. Among SICCA participants classified with SS on the basis of the American-European Consensus Group or American College of Rheumatology criteria, only 2% required the anti-SSB-alone test result to meet these criteria. CONCLUSIONS: The presence of anti-SSB, without anti-SSA antibodies, had...... participants, 2061 (63%) had negative anti-SSA/anti-SSB, 1162 (35%) had anti-SSA with or without anti-SSB, and 74 (2%) anti-SSB alone. Key SS phenotypic features were more prevalent and had measures indicative of greater disease activity in those participants with anti-SSA, either alone or with anti-SSB, than...... in those with anti-SSB alone or negative SSA/SSB serology. These between-group differences were highly significant and not explained by confounding by age, race/ethnicity or gender. Participants with anti-SSB alone were comparable to those with negative SSA/SSB serology in their association with these key...

  15. Albedo Neutron Dosimetry in a Deep Geological Disposal Repository for High-Level Nuclear Waste.

    Science.gov (United States)

    Pang, Bo; Becker, Frank

    2017-04-28

    Albedo neutron dosemeter is the German official personal neutron dosemeter in mixed radiation fields where neutrons contribute to personal dose. In deep geological repositories for high-level nuclear waste, where neutrons can dominate the radiation field, it is of interest to investigate the performance of albedo neutron dosemeter in such facilities. In this study, the deep geological repository is represented by a shielding cask loaded with spent nuclear fuel placed inside a rock salt emplacement drift. Due to the backscattering of neutrons in the drift, issues concerning calibration of the dosemeter arise. Field-specific calibration of the albedo neutron dosemeter was hence performed with Monte Carlo simulations. In order to assess the applicability of the albedo neutron dosemeter in a deep geological repository over a long time scale, spent nuclear fuel with different ages of 50, 100 and 500 years were investigated. It was found out, that the neutron radiation field in a deep geological repository can be assigned to the application area 'N1' of the albedo neutron dosemeter, which is typical in reactors and accelerators with heavy shielding. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions

    International Nuclear Information System (INIS)

    Souza, J.L. de; Escobedo, J.F.; Tornero, M.T.T.

    1999-01-01

    This paper describes the albedo (r) and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L.), cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22° 54' S; 48° 27' W; 850 m). The solar global irradiance (R g ) and solar reflected radiation (R r ) were used to estimate the albedo through the ratio between R r and R g . The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (R g ) and net short-waves radiation (R c ) as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions. (author) [pt

  17. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    International Nuclear Information System (INIS)

    Freitas, Bruno M.; Silva, Ademir X. da

    2015-01-01

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely 241 Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a 6 LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of 241 Am-Be and 252 Cf were employed, besides 238 Pu-Be. Measurements were also made with scattered and moderated neutron beams, including 252 Cf(D 2 O) reference spectrum, 241 Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  18. Radiative forcing over the conterminous United States due to contemporary land cover land use albedo change

    Science.gov (United States)

    Barnes, Christopher; Roy, David P.

    2008-01-01

    Recently available satellite land cover land use (LCLU) and albedo data are used to study the impact of LCLU change from 1973 to 2000 on surface albedo and radiative forcing for 36 ecoregions covering 43% of the conterminous United States (CONUS). Moderate Resolution Imaging Spectroradiometer (MODIS) snow-free broadband albedo values are derived from Landsat LCLU classification maps located using a stratified random sampling methodology to estimate ecoregion estimates of LCLU induced albedo change and surface radiative forcing. The results illustrate that radiative forcing due to LCLU change may be disguised when spatially and temporally explicit data sets are not used. The radiative forcing due to contemporary LCLU albedo change varies geographically in sign and magnitude, with the most positive forcings (up to 0.284 Wm−2) due to conversion of agriculture to other LCLU types, and the most negative forcings (as low as −0.247 Wm−2) due to forest loss. For the 36 ecoregions considered a small net positive forcing (i.e., warming) of 0.012 Wm−2 is estimated.

  19. Retrieval of the ultraviolet effective snow albedo during 1998 winter campaign in the French Alps.

    Science.gov (United States)

    Smolskaia, Irina; Masserot, Dominique; Lenoble, Jacqueline; Brogniez, Colette; de la Casinière, Alain

    2003-03-20

    A measurement campaign was carried out in February 1998 at Briançon Station, French Alps (44.9 degrees N, 6.65 degrees E, 1,310 m above sea level) in order to determine the UV effective snow albedo that was retrieved for both erythemal and UV-A irradiances from measurements and modeling enhancement factors. The results are presented for 15 cloudless days with very variable snow cover and a small snowfall in the middle of the campaign. Erythemal irradiance enhancement due to the surface albedo was found to decrease from approximately +15% to +5% with a jump to +22% after the snowfall, whereas UV-A irradiance enhancement decreased from 7% to 5% and increased to 15% after the snowfall. Thesevalues fit to effective surface albedos of 0.4, 0.1, and 0.5 for erythemal, and to effective albedos of 0.25, 0.1, and 0.4 for UV-A irradiances, respectively. An unexpected difference between the effective albedos retrieved in the two wavelength regions can be explained by the difference of the environment contribution.

  20. Intercomparison of MODIS Albedo Retrievals and In Situ Measurements Across the Global FLUXNET Network

    Science.gov (United States)

    Cescatti, Alessandro; Marcolla, Barbara; Vannan, Suresh K. Santhana; Pan, Jerry Yun; Roman, Miguel O.; Yang, Xiaoyuan; Ciais, Philippe; Cook, Robert B.; Law, Beverly E.; Matteucci, Girogio; hide

    2012-01-01

    Surface albedo is a key parameter in the Earth's energy balance since it affects the amount of solar radiation directly absorbed at the planet surface. Its variability in time and space can be globally retrieved through the use of remote sensing products. To evaluate and improve the quality of satellite retrievals, careful intercomparisons with in situ measurements of surface albedo are crucial. For this purpose we compared MODIS albedo retrievals with surface measurements taken at 53 FLUXNET sites that met strict conditions of land cover homogeneity. A good agreement between mean yearly values of satellite retrievals and in situ measurements was found (R(exp 2)= 0.82). The mismatch is correlated to the spatial heterogeneity of surface albedo, stressing the relevance of land cover homogeneity when comparing point to pixel data. When the seasonal patterns of MODIS albedo is considered for different plant functional types, the match with surface observation is extremely good at all forest sites. On the contrary, in non-forest sites satellite retrievals underestimate in situ measurements across the seasonal cycle. The mismatch observed at grasslands and croplands sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.

  1. NASA Airborne Snow Observatory: Measuring Spatial Distribution of Snow Water Equivalent and Snow Albedo

    Science.gov (United States)

    Joyce, M.; Painter, T. H.; Bormann, K. J.; Berisford, D. F.; Lai-Norling, J.

    2017-12-01

    The two most critical properties for understanding snowmelt runoff and timing are the spatial and temporal distributions of snow water equivalent (SWE) and snow albedo. Despite their importance in controlling volume and timing of runoff, snowpack albedo and SWE are still largely unquantified in the US and not at all in most of the globe, leaving runoff models poorly constrained. NASA Jet Propulsion Laboratory, in partnership with the California Department of Water Resources, has developed the Airborne Snow Observatory (ASO), an imaging spectrometer and scanning LiDAR system, to quantify SWE and snow albedo, generate unprecedented knowledge of snow properties for cutting edge cryospheric science, and provide complete, robust inputs to water management models and systems of the future. This poster will describe the NASA Airborne Snow Observatory, its outputs and their uses and applications, along with recent advancements to the system and plans for the project's future. Specifically, we will look at how ASO uses its imaging spectrometer to quantify spectral albedo, broadband albedo, and radiative forcing by dust and black carbon in snow. Additionally, we'll see how the scanning LiDAR is used to determine snow depth against snow-free acquisitions and to quantify snow water equivalent when combined with in-situ constrained modeling of snow density.

  2. Observational determination of albedo decrease caused by vanishing Arctic sea ice.

    Science.gov (United States)

    Pistone, Kristina; Eisenman, Ian; Ramanathan, V

    2014-03-04

    The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m(2) of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming.

  3. The Earth's Albedo - The other side to Tyndall's contributions to climate

    Science.gov (United States)

    Stephens, G. L.

    2011-12-01

    Graeme L Stephens Director, Center for Climate Sciences and Juilin Li Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Mail Stop: 233-300 Pasadena, CA 91109 John Tyndall's contributions to understanding earth's climate are mostly thought of in terms of the planets absorbing gases and the greenhouse effect. However, there is another aspect of his contributions that lie in the so-called Tyndall effect that relates to scattering of sunlight by large particles. Such scattering is an important contribution to Earth's albedo. In the days of Tyndall's foundational work on Earth's greenhouse effect, the Earth's albedo was thought to be about 50%. Satellite observations in the late 1960s and early 1970s however led to a revision downwards to about 30%. Modern satellite observations suggest that more than half of this amount comes from reflection of sunlight by clouds. What is remarkable though is that the planet's albedo is almost invariant over the time of advanced satellite measurements despite large variability of cloudiness that has occurred. Furthermore, model projections imply that the albedo of Earth is not expected to change over the projected course of global warming. Thus a number of fundamental question emerge - why is the planet's albedo so constant, what factors really control its change and are there natural processes that act to buffer those changes expected from changes to clouds and other factor within the atmosphere? This talk will address these questions.

  4. Strength of forest-albedo feedback in mid-Holocene climate simulations

    Directory of Open Access Journals (Sweden)

    J. Otto

    2011-09-01

    Full Text Available Reconstructions of the mid-Holocene climate, 6000 years before present, suggest that spring temperatures were higher at high northern latitudes compared to the pre-industrial period. A positive feedback between expansion of forest and climate presumably contributed to this warming. In the presence of snow, forests have a lower albedo than grass land. Therefore, the expansion of forest likely favoured a warming in spring, counteracting the lower insolation at the mid-Holocene.

    We investigate the sensitivity of the vegetation-atmosphere interaction under mid-Holocene orbital forcing with respect to the strength of the forest-albedo feedback by using a comprehensive coupled atmosphere-vegetation model (ECHAM5/JSBACH. We perform two sets of model simulations: a first set of simulations with a relatively weak reduction of albedo of snow by forest; and a second set of simulations with a relatively strong reduction of the albedo of snow by forest.

    We show that the parameterisation of the albedo of snow leads to uncertainties in the temperature signal. Compared to the set with weak snow masking, the simulations with strong snow masking reveal a spring warming that is three times higher, by 0.34 °C north of 60° N. This warming is related to a forest expansion of only 13%.

  5. The Atmospheric Aerosols And Their Effects On Cloud Albedo And Radiative Forcing

    International Nuclear Information System (INIS)

    Stefan, S.; Iorga, G.; Zoran, M.

    2007-01-01

    The aim of this study is to provide results of the theoretical experiments in order to improve the estimates of indirect effect of aerosol on the cloud albedo and consequently on the radiative forcing. The cloud properties could be changed primarily because of changing of both the aerosol type and concentration in the atmosphere. Only a part of aerosol interacts effectively with water and will, in turn, determine the number concentration of cloud droplets (CDNC). We calculated the CDNC, droplet effective radius (reff), cloud optical thickness (or), cloud albedo and radiative forcing, for various types of aerosol. Our results show into what extent the change of aerosol characteristics (number concentration and chemical composition) on a regional scale can modify the cloud reflectivity. Higher values for cloud albedo in the case of the continental (urban) clouds were obtained

  6. UV irradiance and albedo at Union Glacier Camp (Antarctica: a case study.

    Directory of Open Access Journals (Sweden)

    Raul R Cordero

    Full Text Available We report on the first spectral measurements of ultraviolet (UV irradiance and the albedo at a Camp located in the southern Ellsworth Mountains on the broad expanse of Union Glacier (700 m altitude, 79° 46' S; 82° 52'W; about 1,000 km from the South Pole. The measurements were carried out by using a double monochromator-based spectroradiometer during a campaign (in December 2012 meant to weight up the effect of the local albedo on the UV irradiance. We found that the albedo measured at noon was about 0.95 in the UV and the visible part of the spectrum. This high surface reflectivity led to enhancements in the UV index under cloudless conditions of about 50% in comparison with snow free surfaces. Spectral measurements carried out elsewhere as well as estimates retrieved from the Ozone Monitoring Instrument (OMI were used for further comparisons.

  7. Program complex for calculating albedo characteristics of neutron and gamma radiations

    International Nuclear Information System (INIS)

    Zhezlov, A.M.; Zhurov, Yu.V.; Makhon'kov, A.S.; Chernyaev, A.

    1987-01-01

    The RADIUS (FORTRAN-DUBNA, BESM-6 computers) - RADIUS-M (FORTRAN-4 ES computers) program complex, designed to obtain albedo characteristics of neutron and gamma radiation for plane, cylindrical and spherical multilayer reflectors within wide range of energy and angles with regard to scattered particle spatial distribution, is described briefly. The RADIUS program is the KUPOL program modification and designed to calculate differential and integral albedo of neutrons and gamma photons in plane one- and two-layer reflectors. The RADIUS-M program realizes calculational algorithm of twice differential, differential and integral albedo from multilayer plane, cylindrical and spherical reflectors. Local estimation of flux into a point detector using multigroup constant systems is the base of the technique. Particle path in a reflector is simulated according to the maximal cross-section method

  8. Snow and albedo climate change impacts across the United States Northern Great Plains

    Science.gov (United States)

    Fassnacht, S. R.; Cherry, M. L.; Venable, N. B. H.; Saavedra, F.

    2016-02-01

    In areas with a seasonal snowpack, a warmer climate could cause less snowfall, a shallower snowpack, and a change in the timing of snowmelt, all which could reduce the winter albedo and yield an increase in net short-wave radiation. Trends in temperature, precipitation (total and as snow), days with precipitation and snow, and winter albedo were investigated over the 60-year period from 1951 to 2010 for 20 meteorological stations across the Northern Great Plains. This is an area where snow accumulation is shallow but persistent for most of the winter (November to March). The most consistent trends were minimum temperature and days with precipitation, both of which increased at a majority of the stations. Among the stations included, a decrease in the modelled winter albedo was more prevalent than an increase. There was substantial spatial variability in the climate trends. For most variables, the period of record used influenced the magnitude and sign of the significant trends.

  9. Modeling Earth Albedo Currents on Sun Sensors for Improved Vector Observations

    DEFF Research Database (Denmark)

    Bhanderi, Dan

    2006-01-01

    Earth albedo influences vector measurements of the solar line of sight vector, due to the induced current on in the photo voltaics of Sun sensors. Although advanced digital Sun sensors exist, these are typically expensive and may not be suited for satellites in the nano or pico-class. Previously...... for modeling Sun sensor output by incorporating the Earth albedo model is presented. This model utilizes the directional information of in the Earth albedo model, which is achieved by Earth surface partitioning. This allows accurate simulation of the Sun sensor output and the results are consistent with Ørsted...... and useful for space environment simulations, and may be utilized to improve attitude estimation algorithms applying Sun sensor vector observations....

  10. Spatially Complete Global Surface Albedos Derived from Terra/MODIS Data

    Science.gov (United States)

    King, Michael D.; Moody, Eric G.; Schaaf, Crystal B.; Platnick, Steven

    2006-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. , Over five years of land surface anisotropy, diffuse bihemispherical (white-sky) albedo and direct beam directional hemispherical (black-sky) albedo from observations acquired by the MODIS instruments aboard NASA s Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal information on the land surface s radiative characteristics. However, roughly 30% of the global land surface, on an annual equal-angle basis, is obscured due to persistent and transient cloud cover, while another 207% is obscured due to ephemeral and seasonal snow effects. This precludes the MOD43B3 albedo products from being directly used in some remote sensing and ground-based applications, climate models, and global change research projects. To provide researchers with the requisite spatially complete global snow-free land surface albedo dataset, an ecosystem-dependent temporal interpolation technique was developed to fill missing or lower quality data and snow covered values from the official MOD43B3 dataset with geophysically realistic values. The method imposes pixel-level and local regional ecosystem-dependent phenological behavior onto retrieved pixel temporal data in such a way as to maintain pixel-level spatial and spectral detail and integrity. The phenological curves are derived from statistics based on the MODIS MOD12Q1 IGBP land cover classification product geolocated with the MOD43B3 data.

  11. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    Directory of Open Access Journals (Sweden)

    A. Lattanzio

    2015-10-01

    Full Text Available Surface albedo has been identified as an important parameter for understanding and quantifying the Earth's radiation budget. EUMETSAT generated the Meteosat Surface Albedo (MSA Climate Data Record (CDR currently comprising up to 24 years (1982–2006 of continuous surface albedo coverage for large areas of the Earth. This CDR has been created within the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM framework. The long-term consistency of the MSA CDR is high and meets the Global Climate Observing System (GCOS stability requirements for desert reference sites. The limitation in quality due to non-removed clouds by the embedded cloud screening procedure is the most relevant weakness in the retrieval process. A twofold strategy is applied to efficiently improve the cloud detection and removal. The first step consists of the application of a robust and reliable cloud mask, taking advantage of the information contained in the measurements of the infrared and visible bands. Due to the limited information available from old radiometers, some clouds can still remain undetected. A second step relies on a post-processing analysis of the albedo seasonal variation together with the usage of a background albedo map in order to detect and screen out such outliers. The usage of a reliable cloud mask has a double effect. It enhances the number of high-quality retrievals for tropical forest areas sensed under low view angles and removes the most frequently unrealistic retrievals on similar surfaces sensed under high view angles. As expected, the usage of a cloud mask has a negligible impact on desert areas where clear conditions dominate. The exploitation of the albedo seasonal variation for cloud removal has good potentialities but it needs to be carefully addressed. Nevertheless it is shown that the inclusion of cloud masking and removal strategy is a key point for the generation of the next MSA CDR release.

  12. The Effect of Bond Albedo on Venus' Atmospheric and Surface Temperatures

    Science.gov (United States)

    Bullock, M. A.; Limaye, S. S.; Grinspoon, D. H.; Way, M.

    2017-12-01

    In spite of Venus' high planetary albedo, sufficient solar energy reaches the surface to drive a powerful greenhouse effect. The surface temperature is three times higher than it would be without an atmosphere. However, the details of the energy balance within Venus' atmosphere are poorly understood. Half of the solar energy absorbed within the clouds, where most of the solar energy is absorbed, is due to an unknown agent. One of the challenges of modeling Venus' atmosphere has been to account for all the sources of opacity sufficient to generate a globally averaged surface temperature of 735 K, when only 2% of the incoming solar energy is deposited at the surface. The wavelength and spherically integrated albedo, or Bond albedo, has typically been cited as between 0.7 and 0.82 (Colin 1983). Yet, recent photometry of Venus at extended phase angles between 2 and 179° indicate a Bond albedo of 0.90 (Mallama et al., 2006). The authors note an increase in cloud top brightness at phase angles right). Venus surface temperature as Bond Albedo changes. Radiative-convective equilibrium models predict the correct globally averaged surface temperature at a=0.81. Calculations here show that a Bond albedo of a=0.9 would yield a surface temperature of 666.4 K, about 70 K too low, unless there is additional thermal absorption within the atmosphere that is not understood. Colin, L.,, Venus, University of Arizona Press, Tucson, 1983, pp 10-26. Mallama, A., et al., 2006. Icarus. 182, 10-22.

  13. Changes in summer sea ice, albedo, and portioning of surface solar radiation in the Pacific sector of Arctic Ocean during 1982-2009

    OpenAIRE

    Lei, Ruibo; Tian-Kunze, Xiangshan; Leppäranta, Matti; Wang, Jia; Kaleschke, Lars; Zhang, Zhanhai

    2016-01-01

    SSM/I sea ice concentration and CLARA black-sky composite albedo were used to estimate sea ice albedo in the region 70 degrees N-82 degrees N, 130 degrees W-180 degrees W. The long-term trends and seasonal evolutions of ice concentration, composite albedo, and ice albedo were then obtained. In July-August 1982-2009, the linear trend of the composite albedo and the ice albedo was -0.069 and -0.046 units per decade, respectively. During 1 June to 19 August, melting of sea ice resulted in an inc...

  14. Response dependence of an albedo-neutron dosemeter on the properties of shielding

    International Nuclear Information System (INIS)

    Doerschel, B.; Herforth, L.; Schuricht, V.

    1976-07-01

    The ratio of the response of an albedo-neutron dosemeter to the biological neutron dose has been calculated for pile and 14-MeV neutrons in dependence on the thickness of several shielding materials, such as iron, water, and concrete. The results obtained show great differences of this ratio for pile and 14-MeV neutrons. Therefore, errors in estimating the biological neutron dose due to changes in the primary neutron energy spectra beyond shields limit the application of simple albedo-neutron dosemeters

  15. A COMPARISON OF OBSERVATION WITH MODELING FOR ALBEDO AND TRANSMITTANCE OF SNOW

    OpenAIRE

    アオキ, テルオ; セコ, カツモト; アオキ, タダオ; フカボリ, マサシ; Teruo, AOKI; Katsumoto, SEKO; Tadao, AOKI; Masashi, FUKABORI

    1994-01-01

    Snow surface albedo and transmittance inside the snow have been investigated by observation and modeling. Observations were taken by a grating type spectrometer at Tokamachi in March 1993. The observed snow was old and very wet. Microscope photo-graphs of snow grains taken at this time indicate that snow grain is spherical particles with size of about 1.0μm. Surface albedo and transmittance of snow by a multiple scattering model for the atmosphere-snow system with pure snow grain size of 1.0μ...

  16. Approximate albedo boundary conditions for energy multigroup X,Y-geometry discrete ordinates nuclear global calculations

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Davi J.M.; Nunes, Carlos E.A.; Alves Filho, Hermes; Barros, Ricardo C., E-mail: davijmsilva@yahoo.com.br, E-mail: ceanunes@yahoo.com.br, E-mail: rcbarros@pq.cnpq.br [Secretaria Municipal de Educacao de Itaborai, RJ (Brazil); Universidade Estacio de Sa (UNESA), Rio de Janeiro, RJ (Brazil); Universidade do Estado do Rio de Janeiro (UERJ), Novra Friburgo, RJ (Brazil). Instituto Politecnico. Departamento de Modelagem Computacional

    2017-11-01

    Discussed here is the accuracy of approximate albedo boundary conditions for energy multigroup discrete ordinates (S{sub N}) eigenvalue problems in two-dimensional rectangular geometry for criticality calculations in neutron fission reacting systems, such as nuclear reactors. The multigroup (S{sub N}) albedo matrix substitutes approximately the non-multiplying media around the core, e.g., baffle and reflector, as we neglect the transverse leakage terms within these non-multiplying regions. Numerical results to a typical model problem are given to illustrate the accuracy versus the computer running time. (author)

  17. Microgeometry capture and RGB albedo estimation by photometric stereo without demosaicing

    Science.gov (United States)

    Quéau, Yvain; Pizenberg, Mathieu; Durou, Jean-Denis; Cremers, Daniel

    2017-03-01

    We present a photometric stereo-based system for retrieving the RGB albedo and the fine-scale details of an opaque surface. In order to limit specularities, the system uses a controllable diffuse illumination, which is calibrated using a dedicated procedure. In addition, we rather handle RAW, non-demosaiced RGB images, which both avoids uncontrolled operations on the sensor data and simplifies the estimation of the albedo in each color channel and of the normals. We finally show on real-world examples the potential of photometric stereo for the 3D-reconstruction of very thin structures from a wide variety of surfaces.

  18. Comparison of using distribution-specific versus effective radius methods for hydrometeor single-scattering properties for all-sky microwave satellite radiance simulations with different microphysics parameterization schemes

    Science.gov (United States)

    Sieron, Scott B.; Clothiaux, Eugene E.; Zhang, Fuqing; Lu, Yinghui; Otkin, Jason A.

    2017-07-01

    The Community Radiative Transfer Model (CRTM) presently uses one look-up table (LUT) of cloud and precipitation single-scattering properties at microwave frequencies, with which any particle size distribution may interface via effective radius. This may produce scattering properties insufficiently representative of the model output if the microphysics parameterization scheme particle size distribution mismatches that assumed in constructing the LUT, such as one being exponential and the other monodisperse, or assuming different particle bulk densities. The CRTM also assigns a 5 μm effective radius to all nonprecipitating clouds, an additional inconsistency. Brightness temperatures are calculated from 3 h convection-permitting simulations of Hurricane Karl (2010) by the Weather Research and Forecasting model; each simulation uses one of three different microphysics schemes. For each microphysics scheme, a consistent cloud scattering LUT is constructed; the use of these LUTs produces differences in brightness temperature fields that would be better for analyzing and constraining microphysics schemes than using the CRTM LUT as-released. Other LUTs are constructed which contain one of the known microphysics inconsistencies with the CRTM LUT as-released, such as the bulk density of graupel, but are otherwise microphysics-consistent; differences in brightness temperature to using an entirely microphysics-consistent LUT further indicate the significance of that inconsistency. The CRTM LUT as-released produces higher brightness temperature than using microphysics-consistent LUTs. None of the LUTs can produce brightness temperatures that can match well to observations at all frequencies, which is likely due in part to the use of spherical particle scattering.

  19. Heart sounds at home: feasibility of an ambulatory fetal heart rhythm surveillance program for anti-SSA-positive pregnancies.

    Science.gov (United States)

    Cuneo, B F; Moon-Grady, A J; Sonesson, S-E; Levasseur, S; Hornberger, L; Donofrio, M T; Krishnan, A; Szwast, A; Howley, L; Benson, D W; Jaeggi, E

    2017-03-01

    Fetuses exposed to anti-SSA (Sjögren's) antibodies are at risk of developing irreversible complete atrioventricular block (CAVB), resulting in death or permanent cardiac pacing. Anti-inflammatory treatment during the transition period from normal heart rhythm (fetal heart rhythm (FHR)) to CAVB (emergent CAVB) can restore sinus rhythm, but detection of emergent CAVB is challenging, because it can develop in ⩽24 h. We tested the feasibility of a new technique that relies on home FHR monitoring by the mother, to surveil for emergent CAVB. We recruited anti-SSA-positive mothers at 16 to 18 weeks gestation (baseline) from 8 centers and instructed them to monitor FHR two times a day until 26 weeks, using a Doppler device at home. FHR was also surveilled by weekly or every other week fetal echo. If FHR was irregular, the mother underwent additional fetal echo. We compared maternal stress/anxiety before and after monitoring. Postnatally, infants underwent a 12-lead electrocardiogram. Among 133 recruited, 125 (94%) enrolled. Among those enrolled, 96% completed the study. Reasons for withdrawal (n=5) were as follows: termination of pregnancy, monitoring too time consuming or moved away. During home monitoring, 9 (7.5%) mothers detected irregular FHR diagnosed by fetal echo as normal (false positive, n=2) or benign atrial arrhythmia (n=7). No CAVB was undetected or developed after monitoring. Questionnaire analysis indicated mothers felt comforted by the experience and would monitor again in future pregnancies. These data suggest ambulatory FHR surveillance of anti-SSA-positive pregnancies is feasible, has a low false positive rate and is empowering to mothers.

  20. Pregnancy outcome of 126 anti-SSA/Ro-positive patients during the past 24 years--a retrospective cohort study.

    Science.gov (United States)

    Luo, Yan; Zhang, Lili; Fei, Yunyun; Li, Yiqun; Hao, Donglin; Liu, Yi; Zhao, Yan

    2015-10-01

    The aims of our study are to observe the pregnancy outcome of anti-Sjögren's syndrome-related antigen A (SSA)/Ro-positive women and to predict the risk factors for adverse pregnancy outcome and neonatal lupus erythematosus (NLE). Clinical data of 126 anti-SSA/Ro-positive patients with 140 pregnancies were evaluated retrospectively, and the newborns were followed up as a cohort in 3 months. χ (2) test or logistic regression was used to predict the risk factors of lupus flares during pregnancy, fetal loss, and NLE. Twenty-six out of 93 pregnancies with systemic lupus erythematosus (SLE) experienced flares during pregnancy. Active disease prior to conception was the independent risk factor for flares [P = 0.002, odds ratio (OR) = 10.41 (95 % confidence interval (CI) = 2.34∼46.26)]. Continuous use of steroids and hydroxychloroquine (HCQ) might help decrease the risk (P = 0.041 and 0.015, respectively). Eleven out of 140 pregnancies ended with fetal loss, and 9 out of 113 live births were diagnosed with NLE. The presence of anti-phospholipid syndrome (APS) was associated with fetal loss (P = 0.018, OR = 6.41 (95 % CI = 1.57-26.14)). The presence of anti-Sjögren's syndrome-related antigen B (SSB)/La antibodies tended to increase the risk of giving birth to an infant with NLE (P = 0.140); on the other hand, duration of disease, history of renal involvement, and active SLE during pregnancy did not contribute to the incidence of NLE (P = 0.649, 0.685, and 1.000, respectively). Active disease without regular follow-up before conception significantly increased the risk of lupus flares during pregnancy. The continuous use of low-dose steroids and hydroxychloroquine might help maintain lower SLE activity. Concurrent APS instead of high titer of anti-SSA/Ro might raise the risk of fetal loss in anti-SSA/Ro-positive patients.

  1. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    NARCIS (Netherlands)

    van Angelen, J.H.|info:eu-repo/dai/nl/325922470; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Lhermitte, S.; Fettweis, X.; Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van Meijgaard, E.; Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236

    2012-01-01

    We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover,

  2. Validation of AVHRR- and MODIS-derived albedos of snow and ice surfaces by means of helicopter measurements

    NARCIS (Netherlands)

    Greuell, W.; Oerlemans, J.

    2005-01-01

    We describe the validation of surface albedos of snow and glacier ice as derived from Advanced Very High Resolution Radiometer (AVHRR) and MOderate Resolution Imaging Spectrometer (MODIS) satellite data. For this purpose we measured surface albedos from a helicopter over Vatnajökull, Iceland, and

  3. Assessment of the surface mass balance along the K-transect (Greenland ice sheet) from satellite-derived albedos

    NARCIS (Netherlands)

    Oerlemans, J.; Greuell, W.

    This paper explores the potential of using satellite-derived albedos to estimate the surface mass balance of the Kangerlussuaq transect (K-transect; Greenland ice sheet). We first retrieved surface albedos from Advanced Very High Resolution Radar data by using, among other techniques, a new

  4. Surface albedo in relation to disturbance and early stand dynamics in the boreal forest: Implications for climate models

    Science.gov (United States)

    Halim, M. A.; Thomas, S. C.

    2017-12-01

    Surface albedo is the most important biophysical radiative forcing in the boreal forest. General Circulation Model studies have suggested that harvesting of boreal forest has a net cooling effect, in contrast to other terrestrial biomes, by increasing surface albedo. However, albedo estimation in these models has been achieved by simplifying processes governing albedo at a coarse scale (both spatial and temporal). Biophysical processes that determine albedo likely operate on small spatial and temporal scales, requiring more direct estimates of effects of landcover change on net radiation. We established a chronosequence study in post-fire and post-clearcut sites (2013, 2006, 1998), logging data from July 2013 to July 2017 in boreal forest sites in northwestern Ontario, Canada. Each age-class X disturbance had 3 three replicates, matched to 18 permanent circular plots (10-m radius) each with an instrumented tower measuring surface albedo, air and soil temperature, and soil moisture. We also measured leaf area index, species composition and soil organic matter content at each site. BRDF-corrected surface albedo was calculated from daily 30m x 30m reflectance data fused from the MODIS MOD09GA product and Landsat 7 reflectance data. Calculated albedo was verified using ground-based measurements. Results show that fire sites generally had lower (15-25%) albedo than clearcut sites in all seasons. Because of rapid forest regrowth, large perturbations of clearcut harvests on forest albedo started to fade out within a year. Albedo differences between fire and clearcut sites also declined sharply with stand age. Younger stands generally had higher albedo than older stands mainly due to the presence of broadleaf species (for example, Populus tremuloides). In spring, snow melted 10-12 days earlier in recent (2013) clearcut sites compared to closed-canopy sites, causing a sharp reduction in surface albedo in comparison to old clearcut/fire sites (2006 and 1998). Snow melted

  5. Production characteristics of lettuce Lactuca sativa L. in the frame of the first crop tests in the Higher Plant Chamber integrated into the MELiSSA Pilot Plant

    Science.gov (United States)

    Tikhomirova, Natalia; Lawson, Jamie; Stasiak, Michael; Dixon, Mike; Paille, Christel; Peiro, Enrique; Fossen, Arnaud; Godia, Francesc

    Micro-Ecological Life Support System Alternative (MELiSSA) is an artificial closed ecosystem that is considered a tool for the development of a bioregenerative life support system for manned space missions. One of the five compartments of MELiSSA loop -Higher Plant Chamber was recently integrated into the MELiSSA Pilot Plant facility at Universitat Aut`noma deo Barcelona. The main contributions expected by integration of this photosynthetic compartment are oxygen, water, vegetable food production and CO2 consumption. Production characteristics of Lactuca sativa L., as a MELiSSA candidate crop, were investigated in this work in the first crop experiments in the MELiSSA Pilot Plant facility. The plants were grown in batch culture and totaled 100 plants with a growing area 5 m long and 1 m wide in a sealed controlled environment. Several replicates of the experiments were carried out with varying duration. It was shown that after 46 days of lettuce cultivation dry edible biomass averaged 27, 2 g per plant. However accumulation of oxygen in the chamber, which required purging of the chamber, and decrease in the food value of the plants was observed. Reducing the duration of the tests allowed uninterrupted test without opening the system and also allowed estimation of the crop's carbon balance. Results of productivity, tissue composition, nutrient uptake and canopy photosynthesis of lettuce regardless of test duration are discussed in the paper.

  6. The role of albedo and accumulation in the 2010 melting record in Greenland

    NARCIS (Netherlands)

    Tedesco, M.; Fettweis, X.; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van de Wal, R.S.W.|info:eu-repo/dai/nl/101899556; Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236; van de Berg, W.J.|info:eu-repo/dai/nl/304831611; Serreze, M.C.; Box, J.E.

    2011-01-01

    Analyses of remote sensing data, surface observations and output from a regional atmosphere model point to new records in 2010 for surface melt and albedo, runoff, the number of days when bare ice is exposed and surface mass balance of the Greenland ice sheet, especially over its west and southwest

  7. Impact of MODIS Sensor Calibration Updates on Greenland Ice Sheet Surface Reflectance and Albedo Trends

    Science.gov (United States)

    Casey, Kimberly A.; Polashenski, Chris M.; Chen, Justin; Tedesco, Marco

    2017-01-01

    We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period 2001-2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500-2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  8. Modelled climate sensitivity of the mass balance of Morteratschgletscher and its dependence on albedo parameterization

    NARCIS (Netherlands)

    Klok, E.J.; Oerlemans, J.

    2004-01-01

    This paper presents a study of the climate sensitivity of the mass balance of Morteratschgletscher in Switzerland, estimated from a two-dimensional mass balance model. Since the albedo scheme chosen is often the largest error source in mass balance models, we investigated the impact of using

  9. Mars seasonal CO2 ice lifetimes and the angular dependence of albedo

    Science.gov (United States)

    Lindner, Bernhard Lee

    1992-01-01

    The albedo of the polar caps on Mars brightens appreciably at high solar zenith angle (Warren et al., J. Geophys. Res., 95, 14717, 1990), an effect not included in prior polar-cap energy-balance models. This decreases absorption of sunlight by the polar cap, hence decreasing sublimation of CO2 ice. Lindner (J. Geophys. Res., 95, 1367, 1990) has shown that the radiative effects of clouds and airborne dust will increase sublimation of CO2 ice over that predicted by prior polar-cap energy-balance models. Furthermore, observations hint that more clouds may exist in the Northern Hemisphere, which Lindner (1990) has shown would sublime CO2 ice more quickly in the north than in the south. I show here that the effects of the solar zenith angle dependence of albedo and the radiative effects of clouds and dust offset each other, but act to extend the lifetime of CO2 ice on the south pole more than on the north pole, possibly explaining the observed hemispherical asymmetry in the residual polar caps without the need of a hemispherical asymmetry in polar-cap albedo required by prior models. Another positive aspect of this solution is that neither the inclusion of the solar zenith angle dependence of albedo nor the radiative effects of clouds and dust should appreciably change prior model agreement with observations of the annual cycle of surface pressure and the recession of the polar caps equatorward of 75 degrees latitude.

  10. Slab albedo for linearly and quadratically anisotropic scattering kernel with modified F{sub N} method

    Energy Technology Data Exchange (ETDEWEB)

    Tuereci, R. Goekhan [Kirikkale Univ. (Turkey). Kirikkale Vocational School; Tuereci, D. [Ministry of Education, Ankara (Turkey). 75th year Anatolia High School

    2017-11-15

    One speed, time independent and homogeneous medium neutron transport equation is solved with the anisotropic scattering which includes both the linearly and the quadratically anisotropic scattering kernel. Having written Case's eigenfunctions and the orthogonality relations among of these eigenfunctions, slab albedo problem is investigated as numerically by using Modified F{sub N} method. Selected numerical results are presented in tables.

  11. Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

    Science.gov (United States)

    Casey, Kimberly A.; Polashenski, Chris M.; Chen, Justin; Tedesco, Marco

    2017-08-01

    We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period 2001-2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500-2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  12. Land Surface Albedo From EPS/AVHRR : Method For Retrieval and Validation

    Science.gov (United States)

    Jacob, G.

    2015-12-01

    The scope of Land Surface Analysis Satellite Applications Facility (LSA-SAF) is to increase benefit from EUMETSAT Satellites (MSG and EPS) data by providing added value products for the meteorological and environmental science communities with main applications in the fields of climate modelling, environmental management, natural hazards management, and climate change detection. The MSG/SEVIRI daily albedo product is disseminated operationally by the LSA-SAF processing centre based in Portugal since 2009. This product so-called MDAL covers Europe and Africa includes in the visible, near infrared and shortwave bands at a resolution of 3km at the equator. Recently, an albedo product at 1km so-called ETAL has been built from EPS/AVHRR observations in order to primarily MDAL product outside the MSG disk, while ensuring a global coverage. The methodology is common to MSG and EPS data and relies on the inversion of the BRDF (Bidirectional Reflectance Distribution Function) model of Roujean et al. On a given target, ETAL products exploits the variability of viewing angles whereas MDAL looks at the variations of solar illumination. The comparison of ETAL albedo product against MODIS and MSG/SEVIRI products over the year 2015 is instructive in many ways and shows in general a good agreement between them. The dispersion may be accounted by different factors that will be explained The additional information provided by EPS appears to be particularly beneficial for high latitudes during winter and for snow albedo.

  13. Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

    Directory of Open Access Journals (Sweden)

    K. A. Casey

    2017-08-01

    Full Text Available We evaluate Greenland Ice Sheet (GrIS surface reflectance and albedo trends using the newly released Collection 6 (C6 MODIS (Moderate Resolution Imaging Spectroradiometer products over the period 2001–2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5. Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry and elevation (i.e., 500–2000 m, 2000 m and greater conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  14. Albedo feedbacks to future climate via climate change impacts on dryland biocrusts

    Science.gov (United States)

    Rutherford, William A.; Painter, Thomas H.; Ferrenberg, Scott; Belnap, Jayne; Okin, Gregory S.; Flagg, Cody; Reed, Sasha C.

    2017-03-01

    Drylands represent the planet’s largest terrestrial biome and evidence suggests these landscapes have large potential for creating feedbacks to future climate. Recent studies also indicate that dryland ecosystems are responding markedly to climate change. Biological soil crusts (biocrusts) ‒ soil surface communities of lichens, mosses, and/or cyanobacteria ‒ comprise up to 70% of dryland cover and help govern fundamental ecosystem functions, including soil stabilization and carbon uptake. Drylands are expected to experience significant changes in temperature and precipitation regimes, and such alterations may impact biocrust communities by promoting rapid mortality of foundational species. In turn, biocrust community shifts affect land surface cover and roughness—changes that can dramatically alter albedo. We tested this hypothesis in a full-factorial warming (+4 °C above ambient) and altered precipitation (increased frequency of 1.2 mm monsoon-type watering events) experiment on the Colorado Plateau, USA. We quantified changes in shortwave albedo via multi-angle, solar-reflectance measurements. Warming and watering treatments each led to large increases in albedo (>30%). This increase was driven by biophysical factors related to treatment effects on cyanobacteria cover and soil surface roughness following treatment-induced moss and lichen mortality. A rise in dryland surface albedo may represent a previously unidentified feedback to future climate.

  15. Influence of soil moisture content on surface albedo and soil thermal ...

    Indian Academy of Sciences (India)

    The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also ...

  16. Albedo feedbacks to future climate via climate change impacts on dryland biocrusts

    Science.gov (United States)

    Rutherford, William A.; Painter, Thomas H.; Ferrenberg, Scott; Belnap, Jayne; Okin, Gregory S.; Flagg, Cody B.; Reed, Sasha C.

    2017-01-01

    Drylands represent the planet’s largest terrestrial biome and evidence suggests these landscapes have large potential for creating feedbacks to future climate. Recent studies also indicate that dryland ecosystems are responding markedly to climate change. Biological soil crusts (biocrusts) ‒ soil surface communities of lichens, mosses, and/or cyanobacteria ‒ comprise up to 70% of dryland cover and help govern fundamental ecosystem functions, including soil stabilization and carbon uptake. Drylands are expected to experience significant changes in temperature and precipitation regimes, and such alterations may impact biocrust communities by promoting rapid mortality of foundational species. In turn, biocrust community shifts affect land surface cover and roughness—changes that can dramatically alter albedo. We tested this hypothesis in a full-factorial warming (+4 °C above ambient) and altered precipitation (increased frequency of 1.2 mm monsoon-type watering events) experiment on the Colorado Plateau, USA. We quantified changes in shortwave albedo via multi-angle, solar-reflectance measurements. Warming and watering treatments each led to large increases in albedo (>30%). This increase was driven by biophysical factors related to treatment effects on cyanobacteria cover and soil surface roughness following treatment-induced moss and lichen mortality. A rise in dryland surface albedo may represent a previously unidentified feedback to future climate.

  17. Influence of soil moisture content on surface albedo and soil thermal ...

    Indian Academy of Sciences (India)

    atively longer memory of soil moisture in com- parison with the variation of controlling parame- ters often leads to climatic ... and vegetation cover changes the soil colour and thus varies the surface albedo (Todd and Hoffer. 1998). .... The colour of the soil at the experimental site varied from dark brown to dark reddish brown.

  18. Calibration of an ALBEDO termoluminiscent dosimeter for its use in personal dosimetry

    International Nuclear Information System (INIS)

    Diaz Bernal, E.; Molina Perez, D.; Cornejo Diaz, N.; Carrazana Gonzalez, J.

    1996-01-01

    The dosimetric studies began after the Radiological Individuals Surveillance Department from the Radiation Protection and Hygiene Center acquired the albedo thermoluminescent dosimeters model JR1104. This paper reviews the response of those dosimeters to the different spectrums and incidence angles of neutronic radiation

  19. Urban Morphology Influence on Urban Albedo: A Revisit with the S olene Model

    Science.gov (United States)

    Groleau, Dominique; Mestayer, Patrice G.

    2013-05-01

    This heuristic study of the urban morphology influence on urban albedo is based on some 3,500 simulations with the S olene model. The studied configurations include square blocks in regular and staggered rows, rectangular blocks with different street widths, cross-shaped blocks, infinite street canyons and several actual districts in Marseilles, Toulouse and Nantes, France. The scanned variables are plan density, facade density, building height, layout orientation, latitude, date and time of the day. The sky-view factors of the ground and canopy surfaces are also considered. This study demonstrates the significance of the facade density, in addition to the built plan density, as the explanatory geometrical factor to characterize the urban morphology, rather than building height. On the basis of these albedo calculations the puzzling results of Kondo et al. (Boundary-Layer Meteorol 100:225-242, 2001) for the influence of building height are explained, and the plan density influence is quantitatively assessed. It is shown that the albedo relationship with plan and facade densities obtained with the regular square plot configuration may be considered as a reference for all other configurations, with the exception of the infinite street canyon that shows systematic differences for the lower plan densities. The curves representing this empirical relationship may be used as a sort of abacus for all other geometries while an approximate simple mathematical model is proposed, as well as relationships between the albedo and sky-view factors.

  20. Deliberating Albedo Modification in Finnish Lapland: Integrating Geoengineering Research With Community-Specific Insights

    Science.gov (United States)

    Buck, H.; Mettiainen, I.; MacMartin, D.; Ricke, K.

    2016-12-01

    Regional social assessments of albedo modification are important for understanding what the social harms and benefits from albedo modification might be in particular contexts. While the Arctic has been posited as a region that could benefit from solar geoengineering, including potential regional albedo modification, few studies have looked at the ideas, concerns, and questions Arctic publics and stakeholders have about geoengineering research. We present the results from public focus groups and in-depth stakeholder interviews conducted in Finnish Lapland. We address questions like: What climate impacts are stakeholders most concerned about, and what climate objectives do varied stakeholders have? How do people see the risks of albedo modification strategies to address those objectives? Why was climate engineering not discussed as an option in Lapland's regional climate strategy? What would Arctic people and industries think if expected economic opportunities due to Arctic sea ice melt failed to materialize, due to geoengineering? The work also explores how in-depth, qualitative methods can help incorporate local perspectives and objectives into the research process. Having local people evaluate potential impacts to their communities, in terms of their own priorities and concerns, generates knowledge about how geoengineering can affect vulnerability and resilience to climate change on community and regional scales. We discuss how lessons learned from this project may apply to regional engagement on geoengineering elsewhere.

  1. Measuring planetary neutron albedo fluxes by remote gamma-ray sensing

    Science.gov (United States)

    Haines, E. L.; Metzger, A. E.

    1984-01-01

    In order to measure the planetary neutron albedo fluxes, a neutron-absorbing shield which emits gamma rays of characteristic energy and serves as a neutron detector, is added to a gamma-ray spectrometer (GRS). The gamma rays representing the neutron flux are observed against interference consisting of cosmic gamma rays, planetary continuum and line emission, and gamma rays arising from the interaction of cosmic rays with the GRS and the spacecraft. The uncertainty and minimum detection limits in neutron albedo fluxes are calculated for two missions, a lunar orbiter and a comet nucleus rendezvous. A GRS on a lunar orbiter at 100 km altitude detects a thermal neutron albedo flux as low as 0.002/sq cm/s and an expected flux of about 0.6/sq cm/s is measured with an uncertainty of 0.001/sq cm/s, for a 100 h observation period. For the comet nucleus, again in a 100 h observing period, a thermal neutron albedo flux is detected at a level of 0.006/sq cm/s and an expected flux of about 0.4/sq cm/s is measured with an uncertainty of 0.004/sq cm/s. The expanded geological capabilities made possible by this technique include improvements in H sensitivity, spatial resolution, and measurement depth; and an improved model of induced gamma-ray emission.

  2. Sensitivity of cloud albedo to aerosol concentration and spectral dispersion of cloud droplet size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Iorga, G. [Faculty of Chemistry, University of Bucharest, Bucharest (Romania)]. E-mail: giorga@gw-chimie.math.unibuc.ro; Stefan, S. [Faculty of Physics, University of Bucharest, Bucharest (Romania)

    2007-07-15

    Both the enhancement of the aerosol number concentration and the relative dispersion of the cloud droplet size distribution (spectral dispersion) on a regional scale can modify the cloud reflectivity. This work is focused on the role that pre-cloud aerosol plays in cloud reflectivity. Log-normal aerosol size distributions were used to describe two aerosol types: marine and rural. The number of aerosols that activate to droplets was obtained based on Abdul-Razzak and Ghan's (2000) activation parameterization. The cloud albedo taking into account the spectral dispersion effect in the parameterization of cloud effective radius and in the scattering asymmetry factor has been estimated. Two different scaling factors to account for dispersion were used. The sensitivity of cloud albedo to spectral dispersion-cloud droplet number concentration relationship in connection to the changes in liquid water content (LWC), and the cloud droplet effective radius has been also investigated. We obtained higher values of effective radius when dispersion is taken into account, with respect to the base case (without considering dispersion). The inferred absolute differences in effective radius values between calculations with each of the scaling factors are below 0.8 {mu}m as LWC ranges between 0.1 and 1.0 g m-3. The optical depth decreased by up to 14% (marine), and up to 29% (continental) when dispersion is considered in both effective radius and asymmetry factor ({beta}LDR scaling factor). Correspondingly, the relative change in cloud albedo is up to 6% (marine) and up to 11% (continental) clouds. For continental clouds, the calculated effective radius when dispersion is considered fits well within the measured range of effective radius in SCAR-B project. The calculated cloud albedo when dispersion is considered shows better agreement with the estimated cloud albedo from measured effective radius in SCAR-B project than the cloud albedo calculated without dispersion. In cleaner

  3. Early Spring Post-Fire Snow Albedo Dynamics in High Latitude Boreal Forests Using Landsat-8 OLI Data

    Science.gov (United States)

    Wang, Zhuosen; Erb, Angela M.; Schaaf, Crystal B.; Sun, Qingsong; Liu, Yan; Yang, Yun; Shuai, Yanmin; Casey, Kimberly A.; Roman, Miguel O.

    2016-01-01

    Taking advantage of the improved radiometric resolution of Landsat-8 OLI which, unlike previous Landsat sensors, does not saturate over snow, the progress of fire recovery progress at the landscape scale (less than 100 m) is examined. High quality Landsat-8 albedo retrievals can now capture the true reflective and layered character of snow cover over a full range of land surface conditions and vegetation densities. This new capability particularly improves the assessment of post-fire vegetation dynamics across low- to high-burn severity gradients in Arctic and boreal regions in the early spring, when the albedos during recovery show the greatest variation. We use 30 m resolution Landsat-8 surface reflectances with concurrent coarser resolution (500 m) MODIS high quality full inversion surface Bidirectional Reflectance Distribution Functions (BRDF) products to produce higher resolution values of surface albedo. The high resolution full expression shortwave blue sky albedo product performs well with an overall RMSE of 0.0267 between tower and satellite measures under both snow-free and snow-covered conditions. While the importance of post-fire albedo recovery can be discerned from the MODIS albedo product at regional and global scales, our study addresses the particular importance of early spring post-fire albedo recovery at the landscape scale by considering the significant spatial heterogeneity of burn severity, and the impact of snow on the early spring albedo of various vegetation recovery types. We found that variations in early spring albedo within a single MODIS gridded pixel can be larger than 0.6. Since the frequency and severity of wildfires in Arctic and boreal systems is expected to increase in the coming decades, the dynamics of albedo in response to these rapid surface changes will increasingly impact the energy balance and contribute to other climate processes and physical feedback mechanisms. Surface radiation products derived from Landsat-8 data will

  4. MODIS-Derived 1.64 micron white-sky albedo on a global, 1-minute equal angle grid (Collection 004 and 005)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Filled Land Surface Albedo Product is a global data set of spatially complete albedo maps. It was derived from the MODIS MOD43B3 Land product and includes both...

  5. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band5 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D66 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  6. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band4 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D65 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  7. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band1 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D62 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  8. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band6 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D67 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  9. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band3 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D64 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  10. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band7 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D68 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  11. MODIS/Terra+Aqua BRDF/Albedo Snow-free Model Parameters Daily L3 Global 0.05Deg CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — Version 6 Bidirectional reflectance distribution function and Albedo (BRDF/Albedo) Model Snow Free Quality Parameters data set is a 5600 meter daily 16-day product....

  12. MODIS Derived 1.24 micron white-sky albedo on a global, 1-minute equal angle grid (Collection 004 and 005)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Filled Land Surface Albedo Product is a global data set of spatially complete albedo maps. It was derived from the MODIS MOD43B3 Land product and includes both s...

  13. MODIS-Derived 0.66 micron white-sky albedo on a global, 1-minute equal angle grid (Collection 004 and 005)

    Data.gov (United States)

    National Aeronautics and Space Administration — Product Description ------------------- The Filled Land Surface Albedo Product is a global data set of spatially complete albedo maps. It was derived from the MODIS...

  14. MODIS/Terra+Aqua BRDF/Albedo QA SnowStatus Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D40 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) QA SnowStatus data set is a daily 16-day product. This product...

  15. MODIS Derived 2.13 micron white-sky albedo on a global, 1-minute equal angle grid (Collection 004 and 005)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Filled Land Surface Albedo Product is a global data set of spatially complete albedo maps. It was derived from the MODIS MOD43B3 Land product and includes both...

  16. MODIS/Terra+Aqua BRDF/Albedo Parameter1 Band6 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D16 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameter data set is a daily 16-day product. This product...

  17. MODIS/Terra+Aqua BRDF/Albedo Nadir BRDF-Adjusted Ref Band2 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D63 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Nadir BRDF Adjusted Reflectance (NBAR) data set is a daily 16-day...

  18. MODIS/Terra+Aqua BRDF/Albedo Parameter2 Band7 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D20 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameter data set is a daily 16-day product. This product...

  19. MODIS/Terra+Aqua BRDF/Albedo Parameter1 VIS Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D22 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameter data set is a daily 16-day product. This product...

  20. MODIS Derived 0.86 micron white-sky albedo on a global, 1-minute equal angle grid (Collection 004 and 005)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Filled Land Surface Albedo Product is a global data set of spatially complete albedo maps. It was derived from the MODIS MOD43B3 Land product and includes both...

  1. MODIS/Terra+Aqua BRDF/Albedo Parameter1 Band2 Daily L3 Global 30ArcSec CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MCD43D04 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameter data set is a daily 16-day product. This product...

  2. BOREAS HYP-8 DEM Data Over The NSA-MSA and SSA-MSA in The AEAC Projection

    Science.gov (United States)

    Knapp, David E.; Hall, Forrest G. (Editor); Wang, Xue-Wen; Band, L. E.; Smith, David E. (Technical Monitor)

    2000-01-01

    These data were derived from the original Digital Elevation Models (DEMs) produced by the Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-8 team. The original DEMs were in the Universal Transverse Mercator (UTM) projection, while this product is projected in the Albers Equal-Area Conic (AEAC) projection. The pixel size of the data is 100 meters, which is appropriate for the 1:50,000-scale contours from which the DEMs were made. The original data were compiled from information available in the 1970s and 1980s. This data set covers the two Modeling Sub-Areas (MSAs) that are contained within the Southern Study Area (SSA) and the Northern Study Area (NSA). The data are stored in binary, image format files. The DEM data over the NSA-MSA and SSA-MSA in the AEAC projection are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  3. Induction of Osmoadaptive Mechanisms and Modulation of Cellular Physiology Help Bacillus licheniformis Strain SSA 61 Adapt to Salt Stress

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Sangeeta; Aggarwal, Chetana; Thakur, Jyoti Kumar; Bandeppa, G. S.; Khan, Md. Aslam; Pearson, Lauren M.; Babnigg, Gyorgy; Giometti, Carol S.; Joachimiak, Andrzej

    2015-01-06

    Bacillus licheniformis strain SSA 61, originally isolated from Sambhar salt lake, was observed to grow even in the presence of 25 % salt stress. Osmoadaptive mechanisms of this halotolerant B. licheniformis strain SSA 61, for long-term survival and growth under salt stress, were determined. Proline was the preferentially accumulated compatible osmolyte. There was also increased accumulation of antioxidants ascorbic acid and glutathione. Among the different antioxidative enzymes assayed, superoxide dismutase played the most crucial role in defense against salt-induced stress in the organism. Adaptation to stress by the organism involved modulation of cellular physiology at various levels. There was enhanced expression of known proteins playing essential roles in stress adaptation, such as chaperones DnaK and GroEL, and general stress protein YfkM and polynucleotide phosphorylase/polyadenylase. Proteins involved in amino acid biosynthetic pathway, ribosome structure, and peptide elongation were also overexpressed. Salt stress-induced modulation of expression of enzymes involved in carbon metabolism was observed. There was up-regulation of a number of enzymes involved in generation of NADH and NADPH, indicating increased cellular demand for both energy and reducing power.

  4. Near-ground cooling efficacies of trees and high-albedo surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen Michael [Univ. of California, Berkeley, CA (United States)

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequentlyproposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object’s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by 0.25 perturbs the object’s surface temperature by -1 to +2 K. Comparing a tree’s canopy-to-air convection to the reduction in ground-to-air convection induced by tree shading of the ground indicates that the presence of a tree can either increase or decrease solar heating of ground-level air. The tree’s net effect depends on the extent to which solar heating of the canopy is dissipated by evaporation, and on the fraction of air heated by the canopy that flows downward and mixes with the ground-level air. A two-month lysimeter (plant-weighing) experiment was conducted to measure instantaneous rates of water loss from a tree under various conditions of weather and soil-moisture. Calculations of canopy-to-air convection and the reduction of ground-to-air convection based on this data indicate that canopy-induced heating would negate shadowinduced cooling if approximately 45% of the canopy-heated air mixed with ground level air. This critical fraction is comparable to typical downward mixing

  5. Analysis of coupled neutron-gamma radiations, applied to shieldings in multigroup albedo method

    International Nuclear Information System (INIS)

    Dunley, Leonardo Souza

    2002-01-01

    The principal mathematical tools frequently available for calculations in Nuclear Engineering, including coupled neutron-gamma radiations shielding problems, involve the full Transport Theory or the Monte Carlo techniques. The Multigroup Albedo Method applied to shieldings is characterized by following the radiations through distinct layers of materials, allowing the determination of the neutron and gamma fractions reflected from, transmitted through and absorbed in the irradiated media when a neutronic stream hits the first layer of material, independently of flux calculations. Then, the method is a complementary tool of great didactic value due to its clarity and simplicity in solving neutron and/or gamma shielding problems. The outstanding results achieved in previous works motivated the elaboration and the development of this study that is presented in this dissertation. The radiation balance resulting from the incidence of a neutronic stream into a shielding composed by 'm' non-multiplying slab layers for neutrons was determined by the Albedo method, considering 'n' energy groups for neutrons and 'g' energy groups for gammas. It was taken into account there is no upscattering of neutrons and gammas. However, it was considered that neutrons from any energy groups are able to produce gammas of all energy groups. The ANISN code, for an angular quadrature order S 2 , was used as a standard for comparison of the results obtained by the Albedo method. So, it was necessary to choose an identical system configuration, both for ANISN and Albedo methods. This configuration was six neutron energy groups and eight gamma energy groups, using three slab layers (iron aluminum - manganese). The excellent results expressed in comparative tables show great agreement between the values determined by the deterministic code adopted as standard and, the values determined by the computational program created using the Albedo method and the algorithm developed for coupled neutron

  6. Impacto do desmatamento de uma área de mangue no albedo superficial

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre Santos Querino

    2013-12-01

    Full Text Available Manguezais são ecossistemas peculiares encontrados nas regiões tropicais. A degradação dos manguezais altera o balanço superficial de radiação, e por consequência o albedo. Para avaliar e comparar o albedo, nesse ambiente foram instaladas duas plataformas de coletas de dados micrometeorológicos no município de Marechal Deodoro, Alagoas, Brasil, no período de outubro de 2004 a outubro de 2005. No mangue nativo (9º42' 18"S; 35º 48' 32" W foram instalados dois piranômetros acima da copa das árvores, e em outubro de 2005, um terceiro dentro do mangue. Na área degradada (9º 36' 38" S; 35º 46' 03" W, os sensores foram posicionados a uma altura de dois metros em relação ao solo. Observou-se que o albedo sobre a floresta de mangue, em geral, é maior em média, 5 pontos percentuais superior em relação à outras florestas tropicais, como por exemplo, a Amazônia. Internamente notou-se que o mesmo não ultrapassou os 13% e seu valor máximo ocorre no horário de menor albedo da copa ≈ 20%, evidenciando a influência da maré. Já na área degradada, o albedo médio foi de 35%, o que implica em uma elevação aproximada de 49% quando substituída a cobertura de floresta natural.

  7. Scatter Correction with Combined Single-Scatter Simulation and Monte Carlo Simulation Scaling Improved the Visual Artifacts and Quantification in 3-Dimensional Brain PET/CT Imaging with15O-Gas Inhalation.

    Science.gov (United States)

    Magota, Keiichi; Shiga, Tohru; Asano, Yukari; Shinyama, Daiki; Ye, Jinghan; Perkins, Amy E; Maniawski, Piotr J; Toyonaga, Takuya; Kobayashi, Kentaro; Hirata, Kenji; Katoh, Chietsugu; Hattori, Naoya; Tamaki, Nagara

    2017-12-01

    In 3-dimensional PET/CT imaging of the brain with 15 O-gas inhalation, high radioactivity in the face mask creates cold artifacts and affects the quantitative accuracy when scatter is corrected by conventional methods (e.g., single-scatter simulation [SSS] with tail-fitting scaling [TFS-SSS]). Here we examined the validity of a newly developed scatter-correction method that combines SSS with a scaling factor calculated by Monte Carlo simulation (MCS-SSS). Methods: We performed phantom experiments and patient studies. In the phantom experiments, a plastic bottle simulating a face mask was attached to a cylindric phantom simulating the brain. The cylindric phantom was filled with 18 F-FDG solution (3.8-7.0 kBq/mL). The bottle was filled with nonradioactive air or various levels of 18 F-FDG (0-170 kBq/mL). Images were corrected either by TFS-SSS or MCS-SSS using the CT data of the bottle filled with nonradioactive air. We compared the image activity concentration in the cylindric phantom with the true activity concentration. We also performed 15 O-gas brain PET based on the steady-state method on patients with cerebrovascular disease to obtain quantitative images of cerebral blood flow and oxygen metabolism. Results: In the phantom experiments, a cold artifact was observed immediately next to the bottle on TFS-SSS images, where the image activity concentrations in the cylindric phantom were underestimated by 18%, 36%, and 70% at the bottle radioactivity levels of 2.4, 5.1, and 9.7 kBq/mL, respectively. At higher bottle radioactivity, the image activity concentrations in the cylindric phantom were greater than 98% underestimated. For the MCS-SSS, in contrast, the error was within 5% at each bottle radioactivity level, although the image generated slight high-activity artifacts around the bottle when the bottle contained significantly high radioactivity. In the patient imaging with 15 O 2 and C 15 O 2 inhalation, cold artifacts were observed on TFS-SSS images, whereas

  8. Evaluation of MODIS albedo product (MCD43A) over grassland, agriculture and forest surface types during dormant and snow-covered periods

    Science.gov (United States)

    Zhuosen Wang; Crystal B. Schaaf; Alan H. Strahler; Mark J. Chopping; Miguel O. Román; Yanmin Shuai; Curtis E. Woodcock; David Y. Hollinger; David R. Fitzjarrald

    2014-01-01

    This study assesses the Moderate-resolution Imaging Spectroradiometer (MODIS) BRDF/albedo 8 day standard product and products from the daily Direct Broadcast BRDF/albedo algorithm, and shows that these products agree well with ground-based albedo measurements during the more difficult periods of vegetation dormancy and snow cover. Cropland, grassland, deciduous and...

  9. Application of Laplace transform for determination of albedo type boundary conditions for neutronic calculations; Aplicacao da transformada de Laplace para determinacao de condicoes de contorno tipo albedo para calculos neutronicos

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Claudio Zen

    2008-07-01

    In this dissertation we use the Laplace transform to derive expressions for nonstandard albedo boundary conditions for one and two non-multiplying regions at the ends of one dimensional domains. In practice, the fuel regions of reactor cores are surrounded by reflector regions that reduce neutron leakage. In order to exclude the reflector regions from the calculations, we introduce a reflection coefficient or albedo. We use the present albedo boundary conditions to solve numerically slab-geometry monoenergetic and multigroup diffusion equations using the conventional finite difference method. Numerical results are generated for fixed source and eigenvalue diffusion problems in slab geometry(author)

  10. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    Directory of Open Access Journals (Sweden)

    J. H. van Angelen

    2012-10-01

    Full Text Available We present a sensitivity study of the surface mass balance (SMB of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6% at the K-transect (west Greenland for the period 2004–2009 is considerably reduced compared to the previous density-dependent albedo scheme (+22%. To simulate realistic snow albedo values, a small concentration of black carbon is needed, which has strongest impact on melt in the accumulation area. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced meltwater retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer that covers the Greenland Ice Sheet.

  11. Modelling Mean Albedo of Individual Roofs in Complex Urban Areas Using Satellite Images and Airborne Laser Scanning Point Clouds

    Science.gov (United States)

    Kalantar, B.; Mansor, S.; Khuzaimah, Z.; Sameen, M. Ibrahim; Pradhan, B.

    2017-09-01

    Knowledge of surface albedo at individual roof scale is important for mitigating urban heat islands and understanding urban climate change. This study presents a method for quantifying surface albedo of individual roofs in a complex urban area using the integration of Landsat 8 and airborne LiDAR data. First, individual roofs were extracted from airborne LiDAR data and orthophotos using optimized segmentation and supervised object based image analysis (OBIA). Support vector machine (SVM) was used as a classifier in OBIA process for extracting individual roofs. The user-defined parameters required in SVM classifier were selected using v-fold cross validation method. After that, surface albedo was calculated for each individual roof from Landsat images. Finally, thematic maps of mean surface albedo of individual roofs were generated in GIS and the results were discussed. Results showed that the study area is covered by 35% of buildings varying in roofing material types and conditions. The calculated surface albedo of buildings ranged from 0.16 to 0.65 in the study area. More importantly, the results indicated that the types and conditions of roofing materials significantly effect on the mean value of surface albedo. Mean albedo of new concrete, old concrete, new steel, and old steel were found to be equal to 0.38, 0.26, 0.51, and 0.44 respectively. Replacing old roofing materials with new ones should highly prioritized.

  12. Spring Snow-Albedo Feedback Analysis Over the Third Pole: Results From Satellite Observation and CMIP5 Model Simulations

    Science.gov (United States)

    Guo, Hui; Wang, Xiaoyi; Wang, Tao; Ma, Yaoming; Ryder, James; Zhang, Taotao; Liu, Dan; Ding, Jinzhi; Li, Yue; Piao, Shilong

    2018-01-01

    The snow-albedo feedback is a crucial component in high-altitude cryospheric change but is poorly quantified over the Third Pole, encompassing the Karakoram and Tibetan Plateau. Here we present an analysis of present-day and future spring snow-albedo feedback over the Third Pole, using a 28 year satellite-based albedo and the latest climate model simulations. We show that present-day spring snow-albedo feedback strength is primarily determined by the decrease in albedo due to snow metamorphosis, rather than that due to reduced snow cover in the Karakoram, but not found in Southeastern Tibet. We further demonstrate an emergent relationship between snow-albedo feedback from the seasonal cycle and that from climate change across models. Combined with contemporary satellite-based snow-albedo feedback from seasonal cycle, this relationship enables us to estimate that the feedback strength for the Karakoram with a relatively high glaciated area is -2.42 ± 0.48% K-1 under an unmitigated scenario, which is much stronger than that for Southeastern Tibet (-1.64 ± 0.48% K-1) and for the Third Pole (-0.89 ± 0.44% K-1), respectively. Moreover, it is noteworthy that the magnitude of the constrained strength is only half of the unconstrained model estimate for the Third Pole, suggesting that current climate models generally overestimate the feedback of spring snow change to temperature change based on the unmitigated scenario.

  13. MODELLING MEAN ALBEDO OF INDIVIDUAL ROOFS IN COMPLEX URBAN AREAS USING SATELLITE IMAGES AND AIRBORNE LASER SCANNING POINT CLOUDS

    Directory of Open Access Journals (Sweden)

    B. Kalantar

    2017-09-01

    Full Text Available Knowledge of surface albedo at individual roof scale is important for mitigating urban heat islands and understanding urban climate change. This study presents a method for quantifying surface albedo of individual roofs in a complex urban area using the integration of Landsat 8 and airborne LiDAR data. First, individual roofs were extracted from airborne LiDAR data and orthophotos using optimized segmentation and supervised object based image analysis (OBIA. Support vector machine (SVM was used as a classifier in OBIA process for extracting individual roofs. The user-defined parameters required in SVM classifier were selected using v-fold cross validation method. After that, surface albedo was calculated for each individual roof from Landsat images. Finally, thematic maps of mean surface albedo of individual roofs were generated in GIS and the results were discussed. Results showed that the study area is covered by 35% of buildings varying in roofing material types and conditions. The calculated surface albedo of buildings ranged from 0.16 to 0.65 in the study area. More importantly, the results indicated that the types and conditions of roofing materials significantly effect on the mean value of surface albedo. Mean albedo of new concrete, old concrete, new steel, and old steel were found to be equal to 0.38, 0.26, 0.51, and 0.44 respectively. Replacing old roofing materials with new ones should highly prioritized.

  14. Ultraviolet radiation (UVR) induces cell-surface Ro/SSA antigen expression by human keratinocytes in vitro: a possible mechanism for the UVR induction of cutaneous lupus lesions

    International Nuclear Information System (INIS)

    Jones, S.K.

    1992-01-01

    Antinuclear antibodies are useful markers of connective tissue disease. In this study, UVB but not UVA induced the expression of Ro/SSA antigen on keratinocyte surfaces in vitro. This expression was also found with the extractable nuclear antigens RnP and Sm, but not with single or double-stranded DNA. The expression was prevented by blocking protein synthesis, suggesting that it was an active process. The results suggest that UVB exposure may result in the expression of Ro/SSA antigen on the surfaces of basal keratinocytes in vivo. This antigen could then bind circulating antibody leading to the cutaneous lesions in neonatal and subacute cutaneous lupus erythematosus. (Author)

  15. An analysis of the potential for achieving the fourth millennium development goal in SSA with domestic resources.

    Science.gov (United States)

    O'Hare, Bernadette; Makuta, Innocent

    2015-02-25

    The importance of good health is reflected in the fact that more than half of the eight Millennium Development Goals (MDGs) are aimed at improving health status. Goal 4 (MDG4) aims to reduce child mortality. The progress indicator for goal 4 is the under-five mortality rate (U5M), with a targeted reduction of two thirds by 2015 from 1990 levels. This paper seeks to compare the time (in years) Sub Saharan African (SSA) countries will take to reach their MDG4 target at the current rate of decline, and the time it could have taken to reach their target if domestic resources had not been lost through illicit financial flows, corruption and servicing of debt since 2000. We estimate the amount by which the Gross Domestic Product (GDP) per capita would increase (in percentage terms) if losses of resource through illicit financial flows, corruption and debt servicing, were reduced. Using the income elasticity of U5M, a metric which reports the percentage change in U5M for a one percent change in GDP per capita, we estimate the potential gains in the annual reduction of the under-five mortality if these resource losses were reduced. At the current rate of reduction in U5M, nine countries out of this sample of 36 SSA countries (25%) will achieve their MDG4 target by 2015. In the absence of the leakages (IFF, corruption and debt service) 30 out of 36 (83%) would reach their MDG4 target by 2015 and all except one country, Zimbabwe would have achieved their MDG4 by 2017 (97%). In view of the uncertainty of the legitimacy of African debts we have also provided results where we excluded debt repayment from our analysis. Most countries would have met MDG4 target by curtailing these outflows. In order to release latent resources in SSA for development, action will be needed both by African countries and internationally. We consider that stemming these outflows, and thereby reducing the need for aid, can be achieved with a more transparent global financial system.

  16. The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Blok, Daan; Heijmans, Monique M P D; Berendse, Frank [Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Schaepman-Strub, Gabriela [Institute of Evolutionary Biology and Environmental Studies, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Bartholomeus, Harm [Centre for Geo-Information, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Maximov, Trofim C, E-mail: daan.blok@wur.nl [Biological Problems of the Cryolithozone, Russian Academy of Sciences, Siberian Division, 41, Lenin Prospekt, Yakutsk, The Republic of Sakha, Yakutia 677980 (Russian Federation)

    2011-07-15

    Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

  17. The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

    International Nuclear Information System (INIS)

    Blok, Daan; Heijmans, Monique M P D; Berendse, Frank; Schaepman-Strub, Gabriela; Bartholomeus, Harm; Maximov, Trofim C

    2011-01-01

    Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

  18. Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

    Directory of Open Access Journals (Sweden)

    O. Meinander

    2013-04-01

    Full Text Available We have measured spectral albedo, as well as ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (67°22' N, 26°39' E. The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX in April 2009. The upwelling and downwelling spectral irradiance, measured at 290–550 nm with a double monochromator spectroradiometer, revealed albedo values of ~0.5–0.7 for the ultraviolet and visible range, both under clear sky and variable cloudiness. During the most intensive snowmelt period of four days, albedo decreased from 0.65 to 0.45 at 330 nm, and from 0.72 to 0.53 at 450 nm. In the literature, the UV and VIS albedo for clean snow are ~0.97–0.99, consistent with the extremely small absorption coefficient of ice in this spectral region. Our low albedo values were supported by two independent simultaneous broadband albedo measurements, and simulated albedo data. We explain the low albedo values to be due to (i large snow grain sizes up to ~3 mm in diameter; (ii meltwater surrounding the grains and increasing the effective grain size; (iii absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon in snow of 87 ppb, and organic carbon 2894 ppb, at the time of albedo measurements. The high concentrations of carbon, detected by the thermal–optical method, were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located.

  19. On the importance of the albedo parameterization for the mass balance of the Greenland ice sheet in EC-Earth

    Directory of Open Access Journals (Sweden)

    M. M. Helsen

    2017-08-01

    Full Text Available The albedo of the surface of ice sheets changes as a function of time due to the effects of deposition of new snow, ageing of dry snow, bare ice exposure, melting and run-off. Currently, the calculation of the albedo of ice sheets is highly parameterized within the earth system model EC-Earth by taking a constant value for areas with thick perennial snow cover. This is an important reason why the surface mass balance (SMB of the Greenland ice sheet (GrIS is poorly resolved in the model. The purpose of this study is to improve the SMB forcing of the GrIS by evaluating different parameter settings within a snow albedo scheme. By allowing ice-sheet albedo to vary as a function of wet and dry conditions, the spatial distribution of albedo and melt rate improves. Nevertheless, the spatial distribution of SMB in EC-Earth is not significantly improved. As a reason for this, we identify omissions in the current snow albedo scheme, such as separate treatment of snow and ice and the effect of refreezing. The resulting SMB is downscaled from the lower-resolution global climate model topography to the higher-resolution ice-sheet topography of the GrIS, such that the influence of these different SMB climatologies on the long-term evolution of the GrIS is tested by ice-sheet model simulations. From these ice-sheet simulations we conclude that an albedo scheme with a short response time of decaying albedo during wet conditions performs best with respect to long-term simulated ice-sheet volume. This results in an optimized albedo parameterization that can be used in future EC-Earth simulations with an interactive ice-sheet component.

  20. Evaluation of MuSyQ land surface albedo based on LAnd surface Parameters VAlidation System (LAPVAS)

    Science.gov (United States)

    Dou, B.; Wen, J.; Xinwen, L.; Zhiming, F.; Wu, S.; Zhang, Y.

    2016-12-01

    satellite derived Land surface albedo is an essential climate variable which controls the earth energy budget and it can be used in applications such as climate change, hydrology, and numerical weather prediction. However, the accuracy and uncertainty of surface albedo products should be evaluated with a reliable reference truth data prior to applications. A new comprehensive and systemic project of china, called the Remote Sensing Application Network (CRSAN), has been launched recent years. Two subjects of this project is developing a Multi-source data Synergized Quantitative Remote Sensin g Production System ( MuSyQ ) and a Web-based validation system named LAnd surface remote sensing Product VAlidation System (LAPVAS) , which aims to generate a quantitative remote sensing product for ecosystem and environmental monitoring and validate them with a reference validation data and a standard validation system, respectively. Land surface BRDF/albedo is one of product datasets of MuSyQ which has a pentad period with 1km spatial resolution and is derived by Multi-sensor Combined BRDF Inversion ( MCBI ) Model. In this MuSyQ albedo evaluation, a multi-validation strategy is implemented by LAPVAS, including directly and multi-scale validation with field measured albedo and cross validation with MODIS albedo product with different land cover. The results reveal that MuSyQ albedo data with a 5-day temporal resolution is in higher sensibility and accuracy during land cover change period, e.g. snowing. But results without regard to snow or changed land cover, MuSyQ albedo generally is in similar accuracy with MODIS albedo and meet the climate modeling requirement of an absolute accuracy of 0.05.