WorldWideScience

Sample records for sun photometer measurements

  1. Urban Visible/SWIR surface reflectance ratios from satellite and sun photometer measurements in Mexico City

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    A. D. de Almeida Castanho

    2007-06-01

    Full Text Available The surface reflectance ratio between the visible (VIS and shortwave infrared (SWIR radiation is an important quantity for the retrieval of the aerosol optical depth (τa from the MODIS sensor data. Based on empirically determined VIS/SWIR ratios, MODIS τa retrieval uses the surface reflectance in the SWIR band (2.1 μm, where the interaction between solar radiation and the aerosol layer is small, to predict the visible reflectances in the blue (0.47 μm and red (0.66 μm bands. Therefore, accurate knowledge of the VIS/SWIR ratio is essential for achieving accurate retrieval of aerosol optical depth from MODIS. The heterogeneity of the surface cover in an urban environment increases the uncertainties in the estimation of the surface reflectance and, consequently, τa. We analyzed the surface reflectance over some distinct surface covers in and around the Mexico City metropolitan area (MCMA using MODIS radiances at 0.66 μm and 2.1 μm. The analysis was performed at 1.5 km×1.5 km spatial resolution. Also, ground-based AERONET sun-photometer data acquired in Mexico City from 2002 to 2005 were analyzed for aerosol optical thickness and other aerosol optical properties. In addition, a network of hand-held sun-photometers deployed in Mexico City, as part of the MCMA-2006 Study during the MILAGRO Campaign, provided an unprecedented measurement of τa in 5 different sites well distributed in the city. We found that the average RED/SWIR ratio representative of the urbanized sites analyzed is 0.73±0.06. This average ratio was significantly different for non-urban sites, which was approximately 0.55. The aerosol optical thickness retrieved from MODIS radiances at a spatial resolution of 1.5 km×1.5 km and averaged within 10 x 10 km boxes were compared with collocated 1-h τa averaged from sun-photometer measurements. The use of the new RED/SWIR ratio of 0.73 in

  2. Retrieval of atmospheric optical parameters from ground-based sun-photometer measurements for Zanjan, Iran

    Science.gov (United States)

    Bayat, A.; Masoumi, A.; Khalesifard, H. R.

    2011-05-01

    We are reporting the results of ground-based spectroradiometric measurements on aerosols and water vapor in the atmosphere of Zanjan for the period of October 2006 to September 2008 using a CIMEL CE318-2 sun-photometer. Zanjan is a city in Northwest Iran, located at 36.70° N, 48.51° E, and at an altitude of 1800 m a.m.s.l. (above mean sea level). The spectral aerosol optical depth, Ångström exponent, and columnar water vapor have been calculated using the data recorded by the sun-photometer through the direct measurements on the sun radiance (sun-mode). The average values of aerosol optical depth at 440 nm, columnar water vapor, and the Ångström exponent, α, during the mentioned period are measured as, 0.28 ± 0.14, 0.57 ± 0.37 cm and 0.73 ± 0.30, respectively. The maximum (minimum) value of the aerosol optical depth was recorded in May 2007 (November 2007), and that of columnar water vapor, in July 2007 (January 2008). Using the least-squares method, the Ångström exponent was calculated in the spectral interval 440-870 nm along with α1 and α2, the coefficients of a second order polynomial fit to the plotted logarithm of aerosol optical depth versus the logarithm of wavelength. The coefficient α2 shows that most of the aerosols in the Zanjan area have dimensions larger than 1 micron. The calculated values for α2 - α1 indicate that 80 % of the aerosols are in the coarse-mode (>1 μm) and 20 % of them are in the fine-mode (<1 μm). Comparison of α2 - α1 for the atmosphere over Zanjan with other regions indicates dust particles are the most dominant aerosols in the region.

  3. Results of SPM sun photometer measurements at Mirny Antarctic station (58-60th RAE)

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    Kabanov, Dmitry M.; Prakhov, Aleksander N.; Radionov, Vladimir F.; Sakerin, Sergey M.

    2015-11-01

    The SPM portable sun photometer observations in the wavelength range of 0.34-2.14 μm are performed at Mirny Antarctic station since fall 2013. The data obtained are used to calculate the aerosol optical depth (AOD) and water vapor content of the atmosphere. The sun photometer intercalibration results and statistical characteristics of interdiurnal and seasonal variations in spectral AOD of the atmosphere are discussed. Estimates of interannual variations in the atmospheric AOD in the region of Mirny station and in the coastal zone of Antarctica are presented. The global background level of AOD of the Antarctic atmosphere is noted to be still about 0.02 at the wavelength of 0.5 μm.

  4. Comparison of the aerosol optical properties and size distribution retrieved by sun photometer with in situ measurements at midlatitude

    Science.gov (United States)

    Chauvigné, Aurélien; Sellegri, Karine; Hervo, Maxime; Montoux, Nadège; Freville, Patrick; Goloub, Philippe

    2016-09-01

    Aerosols influence the Earth radiative budget through scattering and absorption of solar radiation. Several methods are used to investigate aerosol properties and thus quantify their direct and indirect impacts on climate. At the Puy de Dôme station, continuous high-altitude near-surface in situ measurements and low-altitude ground-based remote sensing atmospheric column measurements give the opportunity to compare the aerosol extinction measured with both methods over a 1-year period. To our knowledge, it is the first time that such a comparison is realised with continuous measurements of a high-altitude site during a long-term period. This comparison addresses to which extent near-surface in situ measurements are representative of the whole atmospheric column, the aerosol mixing layer (ML) or the free troposphere (FT). In particular, the impact of multi-aerosol layers events detected using lidar backscatter profiles is analysed. A good correlation between in situ aerosol extinction coefficient and aerosol optical depth (AOD) measured by the Aerosol Robotic Network (AERONET) sun photometer is observed with a correlation coefficient around 0.80, indicating that the in situ measurements station is representative of the overall atmospheric column. After filtering for multilayer cases and correcting for each layer optical contribution (ML and FT), the atmospheric structure seems to be the main factor influencing the comparison between the two measurement techniques. When the site lies in the ML, the in situ extinction represents 45 % of the sun photometer ML extinction while when the site lies within the FT, the in situ extinction is more than 2 times higher than the FT sun photometer extinction. Moreover, the assumption of a decreasing linear vertical aerosol profile in the whole atmosphere has been tested, significantly improving the instrumental agreement. Remote sensing retrievals of the aerosol particle size distributions (PSDs) from the sun photometer

  5. Handheld sun photometer measurements in Southwestern Africa: results from Benin and Ivory Coast.

    Science.gov (United States)

    Leon, Jean-François; Akpo, Aristide; Bedou, Mohamadou; Bodjrenou, Marleine; Djossou, Julien; Konaté, Ismael; Yoboué, Véronique; Liousse, Cathy

    2017-04-01

    The atmosphere of the Gulf of Guinea and adjacent countries is influenced by a large amount of aerosol particles advected from the African continent. This place is one of the hot-spot of aerosol optical depth (AOD) in the world. However AOD in situ observations remains scarce in this area. We present in this paper new measurements of the AOD at 4 sites in southwestern Africa: Cotonou (6.37°N, 2.43°W) and Savè (8.1°N, 2.4°E) cities in Benin, and Abidjan (5.34°N, 3.99°W) city and Lamto (6.22°N, 5.03°W) observatory in Côte d'Ivoire. We use a lightweight handheld sun photometer measuring the solar irradiance at 465, 540 and 619 nm operated manually once per day. Measurements are performed without cloud cover in the field of view. Possible remaining cloud contamination is removed by checking the AOD variability during the measurement sequence. A total of 708 daily observations have been acquired in 2015. The AOD time series in Benin and Ivory Coast highlight a seasonal cycle with a maximum during the dry season (December-Mars) and a minimum during the wet season (May-September). The Angström exponent derived from the spectral AOD measurements enables to attribute the maximum AOD to the presence of large desert dust particles advected by the Harmattan wind during the dry season. We have found an excellent agreement (overall correlation coefficient R=0.85) between our data set and the MODIS (Moderate Imaging Spectroradiometer) aerosol products.

  6. Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET

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    B. Torres

    2013-08-01

    Full Text Available Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The present work relies on the analysis of two new measurement procedures (cross and matrix specifically designed for the evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network (AERONET, the Cimel CE-318 Sun photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a Sun movement correction for an accurate evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show equivalent results with differences under 0.01° in the pointing error estimations. The second part of the analysis includes the incorporation of the cross procedure in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. The pointing error was evaluated using the data collected for more than a year, in 7 Sun photometers belonging to AERONET sites. The registered pointing error values were generally smaller than 0.1°, though in some instruments values up to 0.3° have been observed. Moreover, the pointing error analysis shows that this measurement can be useful to detect mechanical problems in the robots or dirtiness in the 4-quadrant detector used to track the Sun. Specifically, these mechanical faults can be detected due to the stable behavior of the values over time and vs. the solar zenith angle. Finally, the matrix procedure can be used to derive the value of the solid view angle of the instruments. The methodology has been implemented and applied for the characterization of 5 Sun photometers. To validate the method, a comparison with solid angles obtained from the vicarious calibration method was

  7. Nocturnal aerosol optical thickness measured with a sun/moon photometer developed by improving the Prede Sky-radiometer

    Science.gov (United States)

    Shiobara, Masataka; Kobayashi, Hiroshi; Hishida, Kosuke; Uchiyama, Akihiro

    2017-04-01

    Sun photometry to obtain the aerosol optical thickness (AOT) needs the sun. Since the moon must be another source of light instead of the sun during night-time, a moon photometer was developed by improving the Prede POM-02 Sky-radiometer to measure the spectral lunar irradiance. The original POM-02 model has an electric dynamic range of 109 to measure both of direct- and circum-solar radiation. The electronics of POM-02 was upgraded to include a 1011 dynamic range for better performance to measure the direct lunar irradiance at the visible range as well as the sun and sky measurements with a single instrument. A CCD-based position sensor was newly developed to track the moon as well as the sun continuously. The position of the moon/sun is determined with accuracy of better than 0.01° by a real-time processing system using the CCD imager. Test measurements with the improved POM-02 instrument were performed for the half to full moon conditions, and showed a good performance for lunar photometry to obtain the nocturnal AOTs.

  8. A Tracking Sun Photometer Without Moving Parts

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    Strawa, Anthony W.

    2012-01-01

    This innovation is small, lightweight, and consumes very little electricity as it measures the solar energy attenuated by gases and aerosol particles in the atmosphere. A Sun photometer is commonly used on the Earth's surface, as well as on aircraft, to determine the solar energy attenuated by aerosol particles in the atmosphere and their distribution of sizes. This information is used to determine the spatial and temporal distribution of gases and aerosols in the atmosphere, as well as their distribution sizes. The design for this Sun photometer uses a combination of unique optics and a charge coupled device (CCD) array to eliminate moving parts and make the instrument more reliable. It could be selfcalibrating throughout the year. Data products would be down-welling flux, the direct-diffuse flux ratio, column abundance of gas phase constituents, aerosol optical depth at multiple-wavelengths, phase functions, cloud statistics, and an estimate of the representative size of atmospheric particles. These measurements can be used to obtain an estimate of aerosol size distribution, refractive index, and particle shape. Incident light is received at a light-reflecting (inner) surface, which is a truncated paraboloid. Light arriving from a hemispheric field of view (solid angle 2 steradians) enters the reflecting optic at an entrance aperture at, or adjacent to, the focus of the paraboloid, and is captured by the optic. Most of this light is reflected from an inner surface. The light proceeds substantially parallel to the paraboloid axis, and is detected by an array detector located near an exit aperture. Each of the entrance and exit apertures is formed by the intersection of the paraboloid with a plane substantially perpendicular to the paraboloid axis. Incident (non-reflected) light from a source of limited extent (the Sun) illuminates a limited area on the detector array. Both direct and diffuse illumination may be reflected, or not reflected, before being received on

  9. Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements.

    Science.gov (United States)

    Perrone, M R; Burlizzi, P

    2016-07-01

    Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ1, λ2, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 μm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 μm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 μm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but

  10. Aerosol optical properties retrieved from Sun photometer measurements over Shanghai, China

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    He, Qianshan; Li, Chengcai; Geng, Fuhai; Yang, Hequn; Li, Peiren; Li, Tingting; Liu, Dongwei; Pei, Zhen

    2012-08-01

    Using a CIMEL Sun photometer, we conducted continuous observations over the urban area of Shanghai (31°14'N, 121°32'E) from 18 April 2007 to 31 January 2009. The aerosol optical depth (AOD), Angstrom wavelength exponent, single scattering albedo (ω0), and aerosol particle size distribution were derived from the observational data. The monthly mean AOD reached a maximum value of 1.20 in June and a minimum value of 0.43 in January. The monthly averaged Angstrom wavelength exponent reached a minimum value of 1.15 in April and a maximum value of 1.41 in October. The frequencies of the AOD and Angstrom wavelength exponent presented lognormal distributions. The averaged ω0 at 550 nm was 0.94 throughout the observation period, indicating that the aerosols over Shanghai are composed mainly of scattering particles. The concentrations of coarse mode and accumulation mode aerosols over Shanghai were highest in spring compared with other seasons, especially for those particles with radii between 1.0 and 2.0 μm. The median radius of monthly averaged accumulation mode aerosols increased with increasing AOD, and fine particles accounted for the majority of the aerosol volume concentration. The ratios of the monthly averaged volume concentration of accumulation mode and coarse mode aerosols (Vf/Vc) were over 0.6 for all months studied and reached up to 1.94 in August. The volumes of the two modes changed with AOD, but their correlations presented different sensitivities, that is, the volume concentration of accumulation mode aerosols was more sensitive to variations in AOD than that of coarse mode aerosols. The aerosol volume concentration decreased with increasing ω0, indicating that the higher the volume concentration of aerosols, the higher the absorption in particle extinction properties. The increase in absorption was caused primarily by secondary species coated on black carbon (BC) and primary organic carbon (POC) particles.

  11. Retrieval of aerosol single scattering albedo and polarized phase function from polarized sun-photometer measurements for Zanjan atmosphere

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    A. Bayat

    2013-04-01

    Full Text Available Aerosol optical depth, Ångström exponent, single scattering albedo, and polarized phase function have been retrieved from polarized sun-photometer measurements for atmosphere of Zanjan (36.70° N, 48.51° E, and 1800 m a.m.s.l. from January 2010 to December 2012. The results show that the maximum value of aerosol polarized phase function as well as the polarized phase function retrieved for a specific scattering angle (i.e. 60°, are strongly correlated with the Ångström exponent. The latter one has a meaningful variations respect to the changes in the complex refractive index of the atmospheric aerosols. Furthermore the polarized phase function shows a moderate negative correlation respect to atmospheric aerosol optical depth and single scattering albedo. Therefore the polarized phase function can be regarded as a key parameter to characterize the atmospheric particles.

  12. Retrieval of aerosol single-scattering albedo and polarized phase function from polarized sun-photometer measurements for Zanjan's atmosphere

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    A. Bayat

    2013-10-01

    Full Text Available The polarized phase function of atmospheric aerosols has been investigated for the atmosphere of Zanjan, a city in northwest Iran. To do this, aerosol optical depth, Ångström exponent, single-scattering albedo, and polarized phase function have been retrieved from the measurements of a Cimel CE 318-2 polarized sun-photometer from February 2010 to December 2012. The results show that the maximum value of aerosol polarized phase function as well as the polarized phase function retrieved for a specific scattering angle (i.e., 60° are strongly correlated (R = 0.95 and 0.95, respectively with the Ångström exponent. The latter has a meaningful variation with respect to the changes in the complex refractive index of the atmospheric aerosols. Furthermore the polarized phase function shows a moderate negative correlation with respect to the atmospheric aerosol optical depth and single-scattering albedo (R = −0.76 and −0.33, respectively. Therefore the polarized phase function can be regarded as a key parameter to characterize the atmospheric particles of the region – a populated city in the semi-arid area and surrounded by some dust sources of the Earth's dust belt.

  13. Overview of sun photometer measurements of aerosol properties in Scandinavia and Svalbard

    NARCIS (Netherlands)

    Toledano, C.; Cachorro, V.E.; Gausa, M.; Stebel, K.; Aaltonen, V.; Berjón, A.; Ortiz de Galisteo, J.P.; Frutos, A.M. de; Bennouna, Y.; Blindheim, S.; Myhre, C.L.; Zibordi, G.; Wehrli, C.; Kratzer, S.; Hakansson, B.; Carlund, T.; Leeuw, G. de; Herber, A.; Torres, B.

    2012-01-01

    An overview on the data of columnar aerosol properties measured in Northern Europe is provided. Apart from the necessary data gathered in the Arctic, the knowledge of the aerosol loading in nearby areas (e.g. sub-Arctic) is of maximum interest to achieve a correct analysis of the Arctic aerosols and

  14. Improved total atmospheric water vapour amount determination from near-infrared filter measurements with sun photometers

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    F. Mavromatakis

    2007-05-01

    Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We use gaussian-shaped filters as well as actual filter transmission curves to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940 nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10−6 to 10−4, and typical response curves of commercially available silicon photodiodes are included into the calculations. It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is systematically underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. We apply published parameterized transmittance functions to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. Further investigations will use experimental data from field campaigns to validate these findings.

  15. Absolute spectral radiance responsivity calibration of sun photometers

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qiuyun; Zheng Xiaobing; Zhang Wei; Wang Xianhua; Li Jianjun; Li Xin [Key Laboratory of Optical Calibration and Characterization, Chinese Academy of Sciences, Hefei 230031 (China); Li Zhengqiang [Laboratoire d' Optique Atmospherique, Universite Lille 1, Villeneuve d' Ascq 59655 (France) and State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101 (China)

    2010-03-15

    Sun photometers are designed to measure direct solar irradiance and diffused sky radiance for the purpose of atmospheric parameters characterization. A sun photometer is usually calibrated by using a lamp-illuminated integrating sphere source for its band-averaged radiance responsivity, which normally has an uncertainty of 3%-5% at present. Considering the calibration coefficients may also change with time, a regular high precision calibration is important to maintain data quality. In this paper, a tunable-laser-based facility for spectral radiance responsivity calibration has been developed at the Key Laboratory of Optical Calibration and Characterization, Chinese Academy of Sciences. A reference standard radiance radiometer, calibrated against cryogenic radiometer, is used to determine the radiance from a laser-illuminated integrating sphere source. Spectral radiance responsivity of CIMEL CE318-2 sun photometer is calibrated using this new calibration system with a combined standard uncertainty of about 0.8%. As a validation, the derived band-averaged radiance responsivity are compared to that from a Goddard Space Flight Center lamp-based sphere calibration and good agreements (difference <1.4%) are found from 675 to 1020 nm bands.

  16. Absolute spectral radiance responsivity calibration of sun photometers.

    Science.gov (United States)

    Xu, Qiuyun; Zheng, Xiaobing; Li, Zhengqiang; Zhang, Wei; Wang, Xianhua; Li, Jianjun; Li, Xin

    2010-03-01

    Sun photometers are designed to measure direct solar irradiance and diffused sky radiance for the purpose of atmospheric parameters characterization. A sun photometer is usually calibrated by using a lamp-illuminated integrating sphere source for its band-averaged radiance responsivity, which normally has an uncertainty of 3%-5% at present. Considering the calibration coefficients may also change with time, a regular high precision calibration is important to maintain data quality. In this paper, a tunable-laser-based facility for spectral radiance responsivity calibration has been developed at the Key Laboratory of Optical Calibration and Characterization, Chinese Academy of Sciences. A reference standard radiance radiometer, calibrated against cryogenic radiometer, is used to determine the radiance from a laser-illuminated integrating sphere source. Spectral radiance responsivity of CIMEL CE318-2 sun photometer is calibrated using this new calibration system with a combined standard uncertainty of about 0.8%. As a validation, the derived band-averaged radiance responsivity are compared to that from a Goddard Space Flight Center lamp-based sphere calibration and good agreements (difference <1.4%) are found from 675 to 1020 nm bands.

  17. [Research on absolute calibration of sun channel of sun photometer using laser raster scanning method].

    Science.gov (United States)

    Xu, Wen-Bin; Li, Jian-Jun; Zheng, Xiao-Bing

    2013-01-01

    In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3.75%. In the last, the uncertainties of calibration were evaluated and reached to 2.06%. The principle feasibility of the new method was validated.

  18. Calibration of of Sun Photometers and Sky Radiance Sensors. Chapter 3

    Science.gov (United States)

    Pietras, Christophe; Miller, Mark; Frouin, Robert; Eck, Tom; Holben, Brent; Marketon, John

    2001-01-01

    The main source of error in retrieving aerosol optical thicknesses using sun photometry comes from the determination of the TOA voltages. The degradation of interference filters is the most important source of the long-term changes in the cross-calibrations. Although major improvements have been made in the design of the filters (interference filters fabricated using ion-assisted deposition), the filters remain the principal factor limiting performance of the sun photometers. Degradation of filters necessitates frequent calibration of sun photometers and frequent measurements of the filter transmission or the relative system response. The degradation of the filters mounted on the CIMEL sun photometers have been monitored since 1993 by the Aerosol Robotic Network (AERONET) project. The decay reported by Holben et al. for the first two years of a CIMEL#s operation is between 1 and 5%. Nevertheless, the filters mounted on CIMEL instruments are regularly replaced after two years of use. The cross-calibration technique consists of taking measurements concurrently with the uncalibrated and the reference sun photometers. While analyzing measurements, the quality of the calibration has to be checked, using the following considerations: (1) any cirrus clouds suspected to be masking the sun, during the calibration period, need to be reported and the corresponding data set removed; and (2) the stability of the day needs to be checked. This chapter will describe calibration techniques, facilities, and protocols used for calibrating sun photometers and sky radiometers.

  19. Retrieval of ozone column content from airborne Sun photometer measurements during SOLVE II: comparison with coincident satellite and aircraft measurements

    Directory of Open Access Journals (Sweden)

    J. M. Livingston

    2005-01-01

    Full Text Available During the 2003 SAGE (Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment (SOLVE II, the fourteen-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14 was mounted on the NASA DC-8 aircraft and measured spectra of total and aerosol optical depth (TOD and AOD during the sunlit portions of eight science flights. Values of ozone column content above the aircraft have been derived from the AATS-14 measurements by using a linear least squares method that exploits the differential ozone absorption in the seven AATS-14 channels located within the Chappuis band. We compare AATS-14 columnar ozone retrievals with temporally and spatially near-coincident measurements acquired by the SAGE III and the Polar Ozone and Aerosol Measurement (POAM III satellite sensors during four solar occultation events observed by each satellite. RMS differences are 19 DU (7% of the AATS value for AATS-SAGE and 10 DU (3% of the AATS value for AATS-POAM. In these checks of consistency between AATS-14 and SAGE III or POAM III ozone results, the AATS-14 analyses use airmass factors derived from the relative vertical profiles of ozone and aerosol extinction obtained by SAGE III or POAM III. We also compare AATS-14 ozone retrievals for measurements obtained during three DC-8 flights that included extended horizontal transects with total column ozone data acquired by the Total Ozone Mapping Spectrometer (TOMS and the Global Ozone Monitoring Experiment (GOME satellite sensors. To enable these comparisons, the amount of ozone in the column below the aircraft is estimated either by assuming a climatological model or by combining SAGE and/or POAM data with high resolution in-situ ozone measurements acquired by the NASA Langley Research Center chemiluminescent ozone sensor, FASTOZ, during the aircraft vertical profile at the start or end of each flight. Resultant total column ozone values agree with corresponding TOMS and GOME measurements to within 10

  20. Retrieval of ozone column content from airborne Sun photometer measurements during SOLVE II: comparison with coincident satellite and aircraft measurements

    Directory of Open Access Journals (Sweden)

    J. M. Livingston

    2005-01-01

    Full Text Available During the 2003 SAGE (Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment (SOLVE II, the fourteen-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14 was mounted on the NASA DC-8 aircraft and measured spectra of total and aerosol optical depth (TOD and AOD during the sunlit portions of eight science flights. Values of ozone column content above the aircraft have been derived from the AATS-14 measurements by using a linear least squares method that exploits the differential ozone absorption in the seven AATS-14 channels located within the Chappuis band. We compare AATS-14 columnar ozone retrievals with temporally and spatially near-coincident measurements acquired by the SAGE III and the Polar Ozone and Aerosol Measurement (POAM III satellite sensors during four solar occultation events observed by each satellite. RMS differences are 19 DU (6% of the AATS value for AATS-SAGE and 10 DU (3% of the AATS value for AATS-POAM. In these checks of consistency between AATS-14 and SAGE III or POAM III ozone results, the AATS-14 analyses use airmass factors derived from the relative vertical profiles of ozone and aerosol extinction obtained by SAGE III or POAM III.

    We also compare AATS-14 ozone retrievals for measurements obtained during three DC-8 flights that included extended horizontal transects with total column ozone data acquired by the Total Ozone Mapping Spectrometer (TOMS and the Global Ozone Monitoring Experiment (GOME satellite sensors. To enable these comparisons, the amount of ozone in the column below the aircraft is estimated either by assuming a climatological model or by combining SAGE and/or POAM data with high resolution in-situ ozone measurements acquired by the NASA Langley Research Center chemiluminescent ozone sensor, FASTOZ, during the aircraft vertical profile at the start or end of each flight. Resultant total column ozone values agree with corresponding TOMS and GOME measurements to

  1. Estimation of the Total Dust Column and Dry Deposition Flux over the Yellow Sea, China Based on Shipboard Sun Photometer Measurements: Case Study

    Institute of Scientific and Technical Information of China (English)

    YANG Dong-Xu; LIU Yi; CHEN Wen-Zhong

    2010-01-01

    The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MK Ⅱ in a cloud-free and nonfrontal dust condition on 24 April 2006. The total dust column was calculated by using an integration method of the particle size distribution; the mean value was 1.42±0.30 g m-2. A linear correlation between the total dust column and the aerosol optical depth (AOD) with a linear factor of 2.7 g m-2 over the Sahara was applied to calculate the total dust column in this study; the results were lower than these calculated by the integration method. A reasonable factor of 3.2 g m-2 was achieved by minimizing the standard deviation (SD) of the two methods. The two layers model, which includes the deposition processes of turbulent transfer, Brownian diffusion, impaction and gravitational settling over the sea's surface, was used to calculate the dry deposition flux; the mean value was 5.05±2.49 μg m-2 s-1. A correlation among the total dust column, dry deposition flux, AOD, and effective radius was discussed. The correlation between the total dust column and the AOD was better than that between the total dust column and the effective radius; however, the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.

  2. Technical Note: Improved total atmospheric water vapour amount determination from near-infrared filter measurements with sun photometers

    Directory of Open Access Journals (Sweden)

    F. Mavromatakis

    2007-09-01

    Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We employ gaussian-shaped filters as well as actual filter transmission curves, mainly AERONET data, to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. Published parameterized transmittance functions are applied to the data to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940-nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10−6 to 10−4, and typical response curves of commercially available silicon photodiodes are included into the calculations.

    It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is mainly underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. Further investigations will use experimental data from field campaigns to validate these findings.

  3. Validation and understanding of Moderate Resolution Imaging Spectroradiometer aerosol products (C5) using ground-based measurements from the handheld Sun photometer network in China

    Science.gov (United States)

    Zhanqing Li; Feng Niu; Kwon-Ho Lee; Jinyuan Xin; Wei Min Hao; Bryce L. Nordgren; Yuesi Wang; Pucai Wang

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) currently provides the most extensive aerosol retrievals on a global basis, but validation is limited to a small number of ground stations. This study presents a comprehensive evaluation of Collection 4 and 5 MODIS aerosol products using ground measurements from the Chinese Sun Hazemeter Network (CSHNET). The...

  4. Analysis of aerosol properties derived from sun photometer and lidar over Dunhuang radiometric calibration site

    Science.gov (United States)

    Chen, Lin; Jing, Yingying; Zhang, Peng; Hu, Xiuqing

    2016-05-01

    Duhuang site has been selected as China Radiation Calibration Site (CRCS) for Remote Sensing Satellite Sensors since 1996. With the economic development of Dunhuang city, the ambient of the radiation calibration field has changed in recent years. Taking into account the key role of aerosol in radiometric calibration, it is essential to investigate the aerosol optical properties over Dunhuang radiometric calibration site. In this paper, the CIMEL sun photometer (CE-318) and Mie-scattering Lidar are simultaneously used to measure aerosol optical properties in Dunhuang site. Data from aerosol-bands of sun photometer are used in a Langley method to determine spectral optical depths of aerosol. And Lidar is utilized to obtain information of vertical profile and integrated aerosol optical depths at different heights. The results showed that the aerosol optical depth at 500 nm wavelength during the in-situ measurement campaigns varied from 0.1 to 0.3 in Dunhuang site. And the observation results also indicated that high aerosol concentration layer mostly located at the height of about 2~4 km. These results implies that the aerosol concentration of atmosphere in Dunhuang was relatively small and suitable for in-flight calibration for remote sensing satellite sensors.

  5. A New Method for Common Calibration of Sun-Sky-Lunar Photometer

    Science.gov (United States)

    Li, Kaitao; Li, Zhengqiang; Li, Donghui; Xu, Hua; Xie, Yisong; Li, Li; Chen, Xingfeng; Ma, Yan

    2016-04-01

    A new calibration method is introduced to transfer extraterrestrial calibration coefficients to the moon measurements for a new sun-sky-lunar photometer, trade name CE318-T from CIMEL. The new transfer method has no relationship with lunar phase, therefore, the precision of the results is improved, and error analysis suggests that the uncertainty of the transferred method is about 2.2-2.6%, smaller than the lunar Langley calibrations. At the same time, the calibration time is also saved. The Sun-Sky-Lunar photometer numbered #1202 and located on the roof of Institute of remote sensing and digital earth (RADI) in Beijing was used in this study. The extraterrestrial calibration coefficients were got by using Langley calibration performed at Ali with a height of 5053 m above sea level in Tibet. The new lunar calibration coefficients were obtained with the new transfer method. And then the nocturnal AODs were calculated, which are well consistent with the daytime observations. The differences between two AODs obtained with transferred calibration coefficients and lunar Langley method were also compared in this paper. In this study, Lidar observation results was also presented to compare with the lunar observations, the results show that the nocturnal AODs have the same variation tendency with the Lidar observations.

  6. Near-infrared extension of a visible spectrum airborne Sun photometer

    Science.gov (United States)

    Starace, Marco; von Bismarck, Jonas; Hollstein, André; Ruhtz, Thomas; Preusker, René; Fischer, Jürgen

    2013-05-01

    The continuously-measuring, multispectral airborne Sun and aureole photometers FUBISS-ASA and FUBISSASA2 were developed at the Institute for Space Sciences of the Freie Universität Berlin in 2002 and 2006 respectively, for the retrieval of aerosol optical and microphysical parameters at wavelengths ranging from 400 to 900 nm. A multispectral near-infrared direct sun radiometer measuring in a spectral range of 1000 to 1700 nm has now been added to FUBISS-ASA2. The main objective of this NIR extension is to enhance the characterization of larger aerosol particles, as Mie scattering theory offers a more accurate approximation for their interaction with electromagnetic radiation, if both the VIS and NIR parts of the spectrum are considered, than it does for the VIS part only. The spectral transmissivity of atmospheric models was computed using the HITRAN2008 database in order to determine local absorption minima suitable for aerosol retrieval. Measurements were first carried out aboard the research vessel FS Polarstern on its transatlantic voyage ANT-XXVI/1. Additional measurements were performed from the Sphinx High Altitude Research Station on the Jungfraujoch and in the nearby Kleine Scheidegg locality during the CLACE2010 measurement campaign. Aerosol optical parameters derived from VIS aureole and direct sun measurements were compared to those of simulated aerosol mixtures in order to estimate the composition of the measured aerosol.

  7. The new sun-sky-lunar Cimel CE318-T multiband photometer - a comprehensive performance evaluation

    Science.gov (United States)

    Barreto, África; Cuevas, Emilio; Granados-Muñoz, María-José; Alados-Arboledas, Lucas; Romero, Pedro M.; Gröbner, Julian; Kouremeti, Natalia; Almansa, Antonio F.; Stone, Tom; Toledano, Carlos; Román, Roberto; Sorokin, Mikhail; Holben, Brent; Canini, Marius; Yela, Margarita

    2016-02-01

    This paper presents the new photometer CE318-T, able to perform daytime and night-time photometric measurements using the sun and the moon as light source. Therefore, this new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring to be extracted. In this study we have found significantly higher precision of triplets when comparing the CE318-T master instrument and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, two new methodologies to transfer the calibration from a reference instrument using only daytime measurements (Sun Ratio and Sun-Moon gain factor techniques) are presented and discussed. These methods allow the reduction of the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T AOD uncertainty by means of error propagation theory during daytime revealed AOD uncertainties (uDAOD) for Langley-calibrated instruments similar to the expected values for other reference instruments (0.002-0.009). We have also found uDAOD values similar to the values reported in sun photometry for field instruments ( ˜ 0.015). In the case of the night-time period, the CE318-T-estimated standard combined uncertainty (uNAOD) is dependent not only on the calibration technique but also on illumination conditions and the instrumental noise. These values range from 0.011-0.018 for Lunar Langley-calibrated instruments to 0.012-0.021 for instruments calibrated using the Sun Ratio technique. In the case of moon-calibrated instruments using the Sun-Moon gain factor method and sun-calibrated using the Langley technique, we found uNAOD ranging from 0.016 to 0.017 (up to 0.019 in 440 nm channel), not dependent on any lunar irradiance model.A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to

  8. CSIR South Africa mobile LIDAR—First scientific results: comparison with satellite, sun photometer and model simulations

    OpenAIRE

    Bollig, C.; Mengistu, G.; Sharma, A.; W. Alemu; D. Moema; Tesfaye, M; Sivakumar, V

    2010-01-01

    We present the first scientific results from the Council for Scientific and Industrial Research–National Laser Centre (CSIR-NLC) mobile LIght Detection And Ranging (LIDAR) and its validation and comparison with other ground-based and space-borne measurements. The LIDAR results are compared with aerosol extinction measurements from the Stratosphere Aerosol Gas Experiment (SAGE) II, optical depth derived from sun photometers employed under the AErosol RObotic NETwork (AERONET) and backscatter c...

  9. Comparison of Water Vapor Measurements by Airborne Sun photometer and Near-Coincident In Situ and Satellite Sensors during INTEX-ITCT 2004

    Energy Technology Data Exchange (ETDEWEB)

    Livingston, J.; Schmid, Beat; Redemann, Jens; Russell, P. B.; Ramirez, Samuel; Eilers, J.; Gore, W.; Howard, Samuel; Pommier, J.; Fetzer, E. J.; Seemann, S. W.; Borbas, E.; Wolfe, Daniel; Thompson, Anne M.

    2007-06-06

    We have retrieved columnar water vapor (CWV) from measurements acquired by the 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) during 19 Jetstream 31 (J31) flights over the Gulf of Maine in summer 2004. In this paper we compare AATS-14 water vapor retrievals during aircraft vertical profiles with measurements by an onboard Vaisala HMP243 humidity sensor and by ship radiosondes, and with water vapor profiles retrieved from AIRS measurements during 8 Aqua overpasses. We also compare AATS CWV and MODIS infrared CWV retrievals during 5 Aqua and 5 Terra overpasses. For 35 J31 vertical profiles mean (bias) and rms AATS-minus-Vaisala layer-integrated water vapor (LWV) differences are -7.1% and 8.8%, respectively. For 22 aircraft profiles within 1 h and 130 km of radiosonde soundings, AATS-minus-sonde bias and rms LWV differences are -5.4% and 8.8%, respectively, and corresponding J31 Vaisala-minus-sonde differences are 2.3% and 8.4%, respectively. AIRS LWV retrievals within 80 km of J31 profiles yield lower bias and rms differences compared to AATS or Vaisala retrievals than do AIRS retrievals within 150 km of the J31. In particular, for AIRS-minus-AATS LWV differences, the bias decreases from 8.8% to 5.8%, and the rms difference decreases from 21.5% to 16.4%. Comparison of vertically resolved AIRS water vapor retrievals (LWVA) to AATS values in fixed pressure layers yields biases of -2% to +6% and rms differences of ~20% below 700 hPa. Variability and magnitude of these differences increase significantly above 700 hPa. MODIS IR retrievals of CWV in 205 grid cells (5 x 5-km at nadir) are biased wet by 10.4% compared to AATS over-ocean near surface retrievals. The MODIS Aqua subset (79 grid cells) exhibits a wet bias of 5.1%, and the MODIS-Terra subset (126 grid cells) yields a wet bias of 13.2%.

  10. CSIR South Africa mobile LIDAR—First scientific results: comparison with satellite, sun photometer and model simulations

    Directory of Open Access Journals (Sweden)

    C. Bollig

    2010-02-01

    Full Text Available We present the first scientific results from the Council for Scientific and Industrial Research–National Laser Centre (CSIR-NLC mobile LIght Detection And Ranging (LIDAR and its validation and comparison with other ground-based and space-borne measurements. The LIDAR results are compared with aerosol extinction measurements from the Stratosphere Aerosol Gas Experiment (SAGE II, optical depth derived from sun photometers employed under the AErosol RObotic NETwork (AERONET and backscatter coefficients simulated from weather balloon humidity measurements.

  11. Error analysis of integrated water vapor measured by CIMEL photometer

    Science.gov (United States)

    Berezin, I. A.; Timofeyev, Yu. M.; Virolainen, Ya. A.; Frantsuzova, I. S.; Volkova, K. A.; Poberovsky, A. V.; Holben, B. N.; Smirnov, A.; Slutsker, I.

    2017-01-01

    Water vapor plays a key role in weather and climate forming, which leads to the need for continuous monitoring of its content in different parts of the Earth. Intercomparison and validation of different methods for integrated water vapor (IWV) measurements are essential for determining the real accuracies of these methods. CIMEL photometers measure IWV at hundreds of ground-based stations of the AERONET network. We analyze simultaneous IWV measurements performed by a CIMEL photometer, an RPG-HATPRO MW radiometer, and a FTIR Bruker 125-HR spectrometer at the Peterhof station of St. Petersburg State University. We show that the CIMEL photometer calibrated by the manufacturer significantly underestimates the IWV obtained by other devices. We may conclude from this intercomparison that it is necessary to perform an additional calibration of the CIMEL photometer, as well as a possible correction of the interpretation technique for CIMEL measurements at the Peterhof site.

  12. Comparison of aerosol properties retrieved using GARRLiC, LIRIC, and Raman algorithms applied to multi-wavelength lidar and sun/sky-photometer data

    Science.gov (United States)

    Bovchaliuk, Valentyn; Goloub, Philippe; Podvin, Thierry; Veselovskii, Igor; Tanre, Didier; Chaikovsky, Anatoli; Dubovik, Oleg; Mortier, Augustin; Lopatin, Anton; Korenskiy, Mikhail; Victori, Stephane

    2016-07-01

    Aerosol particles are important and highly variable components of the terrestrial atmosphere, and they affect both air quality and climate. In order to evaluate their multiple impacts, the most important requirement is to precisely measure their characteristics. Remote sensing technologies such as lidar (light detection and ranging) and sun/sky photometers are powerful tools for determining aerosol optical and microphysical properties. In our work, we applied several methods to joint or separate lidar and sun/sky-photometer data to retrieve aerosol properties. The Raman technique and inversion with regularization use only lidar data. The LIRIC (LIdar-Radiometer Inversion Code) and recently developed GARRLiC (Generalized Aerosol Retrieval from Radiometer and Lidar Combined data) inversion methods use joint lidar and sun/sky-photometer data. This paper presents a comparison and discussion of aerosol optical properties (extinction coefficient profiles and lidar ratios) and microphysical properties (volume concentrations, complex refractive index values, and effective radius values) retrieved using the aforementioned methods. The comparison showed inconsistencies in the retrieved lidar ratios. However, other aerosol properties were found to be generally in close agreement with the AERONET (AErosol RObotic NETwork) products. In future studies, more cases should be analysed in order to clearly define the peculiarities in our results.

  13. Mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006: Shape-independent particle properties

    Science.gov (United States)

    Müller, D.; Weinzierl, B.; Petzold, A.; Kandler, K.; Ansmann, A.; Müller, T.; Tesche, M.; Freudenthaler, V.; Esselborn, M.; Heese, B.; Althausen, D.; Schladitz, A.; Otto, S.; Knippertz, P.

    2010-04-01

    Aerosol Robotic Network (AERONET) Sun photometer observations were carried out at Ouarzazate, Morocco, during the Saharan Mineral Dust Experiment (SAMUM) 2006. Data from one measurement day, 19 May 2006, are used to derive particle optical and microphysical parameters with AERONET's latest version of light-scattering model for non-spherical particle geometry. In our analysis we also make use of a novel measurement channel at 1638 nm wavelength. We compare the results to data products obtained by airborne high-spectral-resolution lidar, several ground-based Raman lidar, and airborne and ground-based in situ measurement platforms. We chose that specific measurement day because the dust plume was vertically well mixed. Extinction coefficients from AERONET Sun photometer and lidar observations and in situ measurements agree well. Ångström exponents from Sun photometer and lidar are in close agreement, too. Airborne in situ measurements of dust particle size distributions show larger effective radii than inferred from the AERONET data. Complex refractive indices that are derived with the AERONET algorithm differ from the values obtained with different independent techniques employed in our study. The single-scattering albedo was derived from the airborne observations of particle size distributions and complex refractive indices. Single-scattering albedo differs to the value inferred from the AERONET data. The differences may be attributed to the different effective radii that we obtained from the various techniques. The differences between the data products from the various measurement platforms, however, cannot be generalized, as we could only test data for one measurement day. An analysis of additional measurements is under way.

  14. Simple transfer calibration method for a Cimel Sun-Moon photometer: calculating lunar calibration coefficients from Sun calibration constants.

    Science.gov (United States)

    Li, Zhengqiang; Li, Kaitao; Li, Donghui; Yang, Jiuchun; Xu, Hua; Goloub, Philippe; Victori, Stephane

    2016-09-20

    The Cimel new technologies allow both daytime and nighttime aerosol optical depth (AOD) measurements. Although the daytime AOD calibration protocols are well established, accurate and simple nighttime calibration is still a challenging task. Standard lunar-Langley and intercomparison calibration methods both require specific conditions in terms of atmospheric stability and site condition. Additionally, the lunar irradiance model also has some known limits on its uncertainty. This paper presents a simple calibration method that transfers the direct-Sun calibration constant, V0,Sun, to the lunar irradiance calibration coefficient, CMoon. Our approach is a pure calculation method, independent of site limits, e.g., Moon phase. The method is also not affected by the lunar irradiance model limitations, which is the largest error source of traditional calibration methods. Besides, this new transfer calibration approach is easy to use in the field since CMoon can be obtained directly once V0,Sun is known. Error analysis suggests that the average uncertainty of CMoon over the 440-1640 nm bands obtained with the transfer method is 2.4%-2.8%, depending on the V0,Sun approach (Langley or intercomparison), which is comparable with that of lunar-Langley approach, theoretically. In this paper, the Sun-Moon transfer and the Langley methods are compared based on site measurements in Beijing, and the day-night measurement continuity and performance are analyzed.

  15. Retrievals of aerosol optical depth and Angström exponent from ground-based Sun-photometer data of Singapore.

    Science.gov (United States)

    Salinas, Santo V; Chew, Boon N; Liew, Soo C

    2009-03-10

    The role of aerosols in climate and climate change is one of the factors that is least understood at the present. Aerosols' direct interaction with solar radiation is a well understood mechanism that affects Earth's net radiative forcing. However, quantifying its magnitude is more problematic because of the temporal and spatial variability of aerosol particles. To enhance our understanding of the radiative effects of aerosols on the global climate, Singapore has joined the AERONET (Aerosol Robotic Network) worldwide network by contributing ground-based direct Sun measurements performed by means of a multiwavelength Sun-photometer instrument. Data are collected on an hourly basis, then are uploaded to be fully screened and quality assured by AERONET. We use a one year data record (level 1.5/2.0) of measured columnar atmospheric optical depth, spanning from November 2006 to October 2007, to study the monthly and seasonal variability of the aerosol optical depth and the Angström exponent. We performed independent retrievals of these parameters (aerosol optical depth and Angström exponent) by using the photometer's six available bands covering the near-UV to near-IR (380-1080 nm). As a validation, our independent retrievals were compared with AERONET 1.5/2.0 level direct Sun product.

  16. Studies of aerosol optical depth with the use of Microtops II sun photometers and MODIS detectors in coastal areas of the Baltic Sea

    Science.gov (United States)

    Zawadzka, Olga; Makuch, Przemysław; Markowicz, Krzysztof; Zieliński, Tymon; Petelski, Tomasz; Ulevičius, Vidmantas; Strzałkowska, Agata; Rozwadowska, Anna; Gutowska, Dorota

    2014-04-01

    In this paper we describe the results of a research campaign dedicated to the studies of aerosol optical properties in different regions of both the open Baltic Sea and its coastal areas. During the campaign we carried out simultaneous measurements of aerosol optical depth at 4 stations with the use of the hand-held Microtops II sun photometers. The studies were complemented with aerosol data provided by the MODIS. In order to obtain the full picture of aerosol situation over the study area, we added to our analyses the air mass back-trajectories at various altitudes as well as wind fields. Such complex information facilitated proper conclusions regarding aerosol optical depth and Ångström exponent for the four locations and discussion of the changes of aerosol properties with distance and with changes of meteorological factors. We also show that the Microtops II sun photometers are reliable instruments for field campaigns. They are easy to operate and provide good quality results.

  17. Latitudinal and longitudinal variation in aerosol characteristics from Sun photometer and MODIS over the Bay of Bengal and Arabian Sea during ICARB

    Indian Academy of Sciences (India)

    Sumita Kedia; S Ramachandran

    2008-07-01

    Spatial variations in aerosol optical properties as function of latitude and longitude are analysed over the Bay of Bengal and Arabian Sea during ICARB cruise period of March–May 2006 from in situ sun photometer and MODIS (Terra, Aqua) satellite measurements. Monthly mean 550 nm aerosol optical depths (AODs) over the Bay of Bengal and Arabian Sea show an increase from March to May both in spatial extent and magnitude. AODs are found to increase with latitude from 4°N to 20°N over the Bay of Bengal while over Arabian Sea, variations are not significant. Sun photometer and MODIS AODs agree well within ± 1 variation. Bay of Bengal AOD (0.28) is higher than the Arabian Sea (0.24) latitudinally. Aerosol fine mode fraction (FMF) is higher than 0.6 over Bay of Bengal, while FMF in the Arabian Sea is about 0.5. Bay of Bengal (∼1) is higher than the Arabian Sea value of 0.7, suggesting the dominance of fine mode aerosols over Bay of Bengal which is corroborated by higher FMF values over Bay of Bengal. Air back trajectory analyses suggest that aerosols from different source regions contribute differently to the optical characteristics over the Bay of Bengal and Arabian Sea.

  18. Quadrant photometer for satellite-borne auroral and optical measurements.

    Science.gov (United States)

    Criswell, D R; O'Brien, B J

    1967-06-01

    A multichannel photometer has been developed for space applications requiring low weight and power, no moving parts, and high sensitivity. The photocathode of a special phototube is divided into four electrically and optically distinct quadrants. The system operates without degradation after exposure to full sunlight, and has a sensitivity down to the order of rayleighs (10(6) photons cm(-2) sec(-1)). The complete photometer, including high voltage and control circuitry and signal conditioning with A/D converter and three lenses and interference filters, has a weight of 1.7 kg, power consumption of less than 0.3 W, and switching speeds up to 30 cycles/sec. These are to be compared with a previous multichannel photometer with a moving filter wheel, whose corresponding characteristics were 9 kg, 7-9 W, and 0.1 cycles/sec.

  19. Detailed Aerosol Optical Depth Intercomparison between Brewer and Li-Cor 1800 Spectroradiometers and a Cimel Sun Photometer

    Energy Technology Data Exchange (ETDEWEB)

    Cachorro, V. E.; Berjon, A.; Toledano, C.; Mogo, S.; Prats, N.; de Frutos, A. M.; Sorribas, M.; Vilaplana, J. M.; de la Morena, B. A.; Grobner, Julian; Laulainen, Nels

    2009-08-01

    We present here representative results about a comparison of aerosol optical depth (AOD) using different instruments during three short and intensive campaigns carried out from 1999 to 2001 at El Arenosillo (Huelva, Spain). The specific aim of this study is to determine the level of agreement between three different instruments operating at our station. This activity, however, is part of a broader objective to recover an extended data series of AOD in the UV range obtained from a Brewer spectroradiometer. This instrument may be used to obtain AOD at the same five UV wavelengths used during normal operation for ozone content determination. As part of the validation of the Brewer AOD data recovery process, a Cimel sun photometer and another spectroradiometer, a Licor1800, were used. The Licor1800 spectroradiometer (which covers the spectral range 300-1100 nm) was the first instrument used at this station for aerosol monitoring (1996-99) and it was operated during these intercomparison campaigns (1999-2001) specifically to assess the continuity of the AOD data series. The Cimel sunphotometer was installed at our station at the beginning of 2000 as part of AERONET to provide AOD data over the visible and near infrared spectrum. A detailed comparison of these three instruments is carried out by means of near-simultaneous measurements, with particular emphasis on examining any diurnal AOD variability that may be linked with calibration and/or measurement errors or real atmospheric variability. Because the comparison is carried out from UV (320nm) to near infrared (1020nm) wavelengths under all possible atmospheric conditions (including clouds), AOD values range from near zero up to 1. Absolute AOD uncertainties range from 0.02 for the Cimel to 0.08 for the Brewer, with intermediate values for the Licor1800. All the values during the comparison are in reasonable agreement, when taking into account the different performance characteristics of each instrument. The

  20. Research on Absolute Calibration of Sun Channel of Sun Photometer Using Laser Raster Scanning Method%激光点阵扫描法绝对定标太阳辐射计直射通道研究

    Institute of Scientific and Technical Information of China (English)

    徐文斌; 李健军; 郑小兵

    2013-01-01

    利用可调谐激光器作为光源,以溯源于低温绝对辐射计的标准传递探测器作为激光束功率测量探测器,采用激光点阵扫描方法在太阳辐射计有效孔径光阑面形成均匀照度场,精确测量太阳辐射计870 nm无偏直射通道中心波长处绝对辐照度响应度.利用灯-单色仪系统扫描获得该通道相对光谱辐照度响应度,最终在实验室条件下获得该通道绝对光谱辐照度响应度,联合大气层外太阳照度谱数据通道内积分得到该通道大气层外响应常数V0值,与NASA的GSFC中心的2009年定标结果差异仅为3.75 %,定标不确定度达到2.06%,验证了这一新技术的原理可行性.%In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3. 75%. In the last, the uncertainties of calibration were evaluated and reached to 2. 06%. The principle feasibility of the new method was validated.

  1. Clustering of Sun Exposure Measurements

    DEFF Research Database (Denmark)

    Have, Anna Szynkowiak; Larsen, Jan; Hansen, Lars Kai

    2002-01-01

    In a medically motivated Sun-exposure study, questionnaires concerning Sun-habits were collected from a number of subjects together with UV radiation measurements. This paper focuses on identifying clusters in the heterogeneous set of data for the purpose of understanding possible relations between...... Sun-habits exposure and eventually assessing the risk of skin cancer. A general probabilistic framework originally developed for text and Web mining is demonstrated to be useful for clustering of behavioral data. The framework combines principal component subspace projection with probabilistic...

  2. Comparison of the Changes in the Visible and Infrared Irradiance Observed by the SunPhotometers on EURECA to the UARS Total Solar and UV Irradiances

    Science.gov (United States)

    Pap, Judit

    1995-01-01

    Solar irradiance in the near-UV (335 nm), visible (500 nm) and infrared (778 nm) spectral bands has been measured by the SunPhotometers developed at the World Radiation Center, Davos, Switzerland on board the European Retrievable Carrier between August 1992 and May 1993. Study of the variations in the visible and infrared irradiance is important for both solar and atmospheric physics. The purpose of this paper is to examine the temporal variations observed in the visible and infrared spectral bands after eliminating the trend in the data mainly related to instrument degradation. The effect of active regions in these spectral irradiances is clearly resolved. Variations in the visible and infrared irradiances are compared to total solar irradiance observed by the SOVA2 radiometer on the EURECA platform and by the ACRIMII radiometer on UARS as well as to UV observations of the UARS and NOAA9 satellites. The space-borne spectral irradiance observations are compared to the photometric sunspot deficit and CaII K irradiance measured at the San Fernando Observatory, California State University at Northridge in order to study the effect of active regions in detail.

  3. Comparison of the Changes in the Visible and Infrared Irradiance Observed by the SunPhotometers on EURECA to the UARS Total Solar and UV Irradiances

    Science.gov (United States)

    Pap, Judit

    1995-01-01

    Solar irradiance in the near-UV (335 nm), visible (500 nm) and infrared (778 nm) spectral bands has been measured by the SunPhotometers developed at the World Radiation Center, Davos, Switzerland on board the European Retrievable Carrier between August 1992 and May 1993. Study of the variations in the visible and infrared irradiance is important for both solar and atmospheric physics. The purpose of this paper is to examine the temporal variations observed in the visible and infrared spectral bands after eliminating the trend in the data mainly related to instrument degradation. The effect of active regions in these spectral irradiances is clearly resolved. Variations in the visible and infrared irradiances are compared to total solar irradiance observed by the SOVA2 radiometer on the EURECA platform and by the ACRIMII radiometer on UARS as well as to UV observations of the UARS and NOAA9 satellites. The space-borne spectral irradiance observations are compared to the photometric sunspot deficit and CaII K irradiance measured at the San Fernando Observatory, California State University at Northridge in order to study the effect of active regions in detail.

  4. CSIR South Africa mobile LIDAR - First scientific results: comparison with satellite, sun photometer and model simulations

    CSIR Research Space (South Africa)

    Sivakumar, V

    2009-11-01

    Full Text Available in Fig. 3b, which further evidences the planetary (nocturnal) boundary layer (PBL) structure. The PBL is found to be at approximately 3 km and is stable without much variation. During the night, when there is no solar input, aerosols are non... thermodynamic chemical reactions causing turbulence in the PBL. The boundary layer height is therefore expected to vary more during the day and to stabilise after sunset. Aerosol extinction measurements by LIDAR and SAGE II When validating the results from...

  5. Studies of aerosol optical depth with use of Microtops sun photometers and MODIS detectors

    Science.gov (United States)

    Makuch, Przemyslaw; Zawadzka, Olga; Markowicz, Krzystof M.; Zielinski, Tymon; Petelski, Tomasz; Strzalkowska, Agata; Rozwadowska, Anna; Gutowska, Dorota

    2013-04-01

    We would like to describe the results of a research campaign aimed at the studies of aerosol optical properties in the regions of the open Baltic Sea as well as coastal areas. During the campaign we carried out simultaneous measurements of aerosol optical depth at 4 stations with use of the hand-held Microtops II sunphotometers. The studies were complemented with the MODIS aerosol data. In order to obtain the full picture of the aerosol situation over the study area we added air mass back-trajectories at various altitudes and wind fields. Such complex information facilitated the proper conclusions regarding aerosol optical depth and Angstroem exponent for the four locations and discussion of the changes of aerosol properties with distance and meteorological factors. We show that Microtops II sunphotometers are reliable instruments for field campaigns. They are easy to operate and provide good quality results. Acknowledgements: The support for this study was provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk founded by European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09.

  6. Using a Homemade Flame Photometer to Measure Sodium Concentration in a Sports Drink

    Science.gov (United States)

    LaFratta, Christopher N.; Jain, Swapan; Pelse, Ian; Simoska, Olja; Elvy, Karina

    2013-01-01

    The purpose of this experiment was to create a simple and inexpensive flame photometer to measure the concentration of sodium in beverages, such as Gatorade. We created a nebulizer using small tubing and sprayed the sample into the base of a Bunsen burner. Adjacent to the flame was a photodiode with a filter specific for the emission of the sodium…

  7. Using a Homemade Flame Photometer to Measure Sodium Concentration in a Sports Drink

    Science.gov (United States)

    LaFratta, Christopher N.; Jain, Swapan; Pelse, Ian; Simoska, Olja; Elvy, Karina

    2013-01-01

    The purpose of this experiment was to create a simple and inexpensive flame photometer to measure the concentration of sodium in beverages, such as Gatorade. We created a nebulizer using small tubing and sprayed the sample into the base of a Bunsen burner. Adjacent to the flame was a photodiode with a filter specific for the emission of the sodium…

  8. Improvement of the quality of the ozone measurements by means of a standard reference photometer

    Directory of Open Access Journals (Sweden)

    C. Sánchez Blaya

    2001-11-01

    Full Text Available The Directive 92/72/CE makes reference to the analysis method described in the UNE 77-221:2000 and to the fact that the ozone analyzers shall be calibrated with a UV reference photometer or with a transfer standard.From the need of developing a procedure that assure the quality and the trazability of the measurements in Spain, the Atmospheric Pollution Area has decided to implant a NIST UV reference photometer as ozone national standard.Taking into account the procedures used by EPA and NIST, a verification procedure has been developed consistent in the realization of 6 comparisons of the Transfer Standard versus NIST UV reference photometer in different days; at least 5 different ozone concentrations are analyzed. Each comparison begins and ends always with a concentration of 0 ppb of O3, and from each comparison its regression linear is obtained.Once the 6 comparisons are done, the calibration relationship is obtained and the uncertainty associated with the transfer standard is calculated.Until now, the verifications of 17 transfer standards have been done: 11 of them were UV photometers, 2 were ozone generators and 4 were ozone generators of dilution banks.From the results is concluded that generally the uncertainties of the ozone generators are greater than those of the UV photometers, so being recommended this one like transfer standard.To emphasize that with the utilization of the tranfer standards for the calibration of ozone analyzers, the quality and the trazability of the generated data are guaranteed.

  9. Dust specific extinction cross-sections over the Eastern Mediterranean using the BSC-DREAM model and sun photometer data: the case of urban environments

    Directory of Open Access Journals (Sweden)

    E. Gerasopoulos

    2009-07-01

    Full Text Available In this study, aerosol optical depth (AOD measurements, from a MFR sun photometer operating in Athens, were compared with columnar dust loading estimations, from the BSC-DREAM model, during identified dust events, in order to extract the typical specific extinction cross-section for dust over the area. The selected urban environment of Athens provided us with the opportunity to investigate the mixing of dust and urban pollution and to estimate the contribution of the latter. The specific extinction cross-section for dust at 500 nm was found to be equal to σ500*=0.64±0.04 m2 g, typical for medium to large distances from dust sources, with weak wavelength dependence in the visible and near infrared band (0.4–0.9 μm. The model showed a tendency to underpredict AOD levels for increasing values of the Ångström exponent, indicative of fine particles of anthropogenic origin inside the boundary layer. On average we found an AOD under-prediction of 10–15% for Ångström exponents in the range of 0 to 1 and 30–40% in the range of 1 to 2. Additionally, modelled surface concentrations were evaluated against surface PM10 measurements. Model values were lower than measured surface concentrations by 30% which, in conjunction with large scatter, indicated that the effect of the boundary layer anthropogenic contribution to columnar dust loadings is amplified near the ground.

  10. CE-318太阳光度计在大气环境监测中的应用%Application of CE-318 Sun Photometer in Atmospheric Environmental Monitoring

    Institute of Scientific and Technical Information of China (English)

    李礼; 余家燕; 杨灿; 唐晓

    2012-01-01

    CE-318 sun photometer plays an important role in atmospheric environmental monitoring and research by scanning the direct solar radiation and sky light automatically and the optical characteristics of atmospheric aerosol can be obtained through specific inversion calculation.The instrument structure,measuring work procedure and inversion algorithm of CE-318 sun photometer were introduced in this paper.The monitoring result of atmospheric angstrom wavelength index in 2010 Chongqing was briefly analyzed.%CE-318太阳光度计自动进行太阳直接辐射和天空光扫描探测,通过反演计算可获取大气气溶胶各种光学特性,在大气环境监测与研究领域发挥着重要作用。介绍了CE-318太阳光度计的仪器结构、测量工作程序和反演算法,并对2010年重庆城区大气Angstrom波长指数测量结果进行了简要分析。

  11. SeaWIFS Postlaunch Technical Report Series. Volume 13; The SeaWiFS Photometer Revision for Incident Surface Measurement (SeaPRISM) Field Commissioning

    Science.gov (United States)

    Hooker, Stanford B. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francois; Bailey, Sean W.; Pietras, Christophe M.; Firestone, Elaine R. (Editor)

    2000-01-01

    This report documents the scientific activities that took place at the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea off the coast of Italy from 2-6 August 1999. The ultimate objective of the field campaign was to evaluate the capabilities of a new instrument called the SeaWiFS Photometer Revision for Incident Surface Measurements (SeaPRISM). SeaPRISM is based on a CE-318 sun photometer made by CIMEL Electronique (Paris, France). The CE-318 is an automated, robotic system which measures the direct sun irradiance plus the sky radiance in the sun plane and in the almucantar plane. The data are transmitted over a satellite link, and this remote operation capability has made the device very useful for atmospheric measurements. The revision to the CE-318 that makes the instrument potentially useful for SeaWiFS calibration and validation activities is to include a capability for measuring the radiance leaving the sea surface in wavelengths suitable for the determination of chlorophyll a concentration. The initial evaluation of this new capability involved above- and in-water measurement protocols. An intercomparison of the water-leaving radiances derived from SeaPRISM and an in-water system showed the overall spectral agreement was approximately 8.6%, but the blue-green channels intercompared at the 5% level. A blue-green band ratio comparison was at the 4% level.

  12. The study of atmospheric correction of satellite remotely sensed images intended for air pollution using sun-photometers (AERONET) and lidar system in Lemesos, Cyprus

    Science.gov (United States)

    Hadjimitsis, Diofantos G.; Themistocleous, Kyriacos; Nisantzi, Argyro; Matsas, Alexandros

    2010-10-01

    Solar radiation reflected by the Earth's surface to satellite sensors is modified by its interaction with the atmosphere. The objective of atmospheric correction is to determine true surface reflectance values by removing atmospheric effects from satellite images. Atmospheric correction is arguably the most important part of the pre-processing of satellite remotely sensed data. The most important parameter in applying any atmospheric correction is the aerosol optical thickness which is also used for assessing air pollution. This paper explores how the AOT is extracted from atmospheric corrected satellite imagery acquired from Landsat ETM + and how then AOT values are used to assess air pollution. The atmospheric correction algorihm developed by Hadjimitsis and Clayton (2009) is applied to short wavelengths like Landsat TM band 1 and 2 (0.45-0.52μm, 0.52-0.60 μm). The results are also assessed using Lidar system and Cimel Sunphotometer located in the premises of the Cyprus University of Technology in Limassol. The authors run the atmospheric correction developed by Hadjimitsis and Clayton (2009) in MATLAB and sample AOT results for the Landsat ETM+ images acquired on the 15/01/2010, 20/4/2010, 09/06/2010 are shown. For the Landsat ETM+ image acquired on 20/4/2010, the AOT was found 1.4 after the application of the atmospheric correction. Such value complies with the AOT value measured by the Cimel Sun-photometer (AERONET) during the satellite overpass. An example of how Lidar is used to assess the existing atmospheric conditions which is useful for assessing air pollution is also presented.

  13. Development and application of the portable full autocontrol sun-photometer%便携式全自动太阳光度计的研制及其应用

    Institute of Scientific and Technical Information of China (English)

    李建玉; 徐文清; 伽丽丽; 詹杰; 高亦桥; 魏合理

    2012-01-01

    研制了一种基于VB平台可实时测量监控的可视化多波长便携式全自动太阳光度计DTF-6,可实现瞬时太阳辐照度、整层大气气溶胶光学厚度和可降水量的实时测量与显示,具有电机运转、太阳跟踪、加热温度等强大的在线检测功能.该仪器是在自行研制的第三第四代太阳光度计的基础上进行的改进,仪器更方便使用、更适应恶劣环境、更小型化和具有更高的性能价格比.通过对实测结果的分析和比较,该仪器令人满意,并给出仪器标定结果,同时对其应用进行了阐述.%A set of portable autocontrol muti-wavalength sun-photometer base on Visual Basic, which is real-time and obvious, is developed. It can measure and display instantaneous solar radiation and atmospheric aerosol optical thickness and precipitable water as well. It is also provided with the on-line detection function of electric engine operation, sun tracing , heating temperature et al. This instrument is improved based on the prototype developed by ourselves. The sun-photometer is more portable and can more accommodate to the abominable environment, more miniaturize and improve the ratio of his performance and price. The measured results of this device are satisfactory via the analysis and compare of measured data Also the instrument calibration and its application are described.

  14. Near infrared emission photometer for measuring the oxidative stability of edible oils.

    Science.gov (United States)

    Vieira, Francisco Senna; Pasquini, Celio

    2013-09-24

    Near infrared emission spectroscopy (NIRES) allows the determination of the induction time (IT) of edible oils in accelerated oxidation experiments by monitoring the emissivity of a band at 2900 nm, which corresponds to the formation of hydroperoxides. In this work, a new near infrared emission photometer dedicated to the determination of oxidative stability is described. The photometer presents several advantages compared to the previously reported NIRES instrument, such as lower cost and extreme simplicity of design and maintenance. The results obtained in the evaluation of the proposed instrument were compared with the official Rancimat method and instrument. The significant advantages include: faster analysis, lower sample consumption and operational simplicity. It is demonstrated that the procedure for determination of oxidative stability of oils can be significantly simplified and performed by measuring the sample emission at only one spectral region centered at 2900 nm. Also, the proposed instrument and method present precision equivalent to the Rancimat method (coefficient of variation=5.0%). A significant correlation between the methods has been found (R(2)=0.81).

  15. Nighttime Aerosol Optical Depth Measurements Using a Ground-based Lunar Photometer

    Science.gov (United States)

    Berkoff, Tim; Omar, Ali; Haggard, Charles; Pippin, Margaret; Tasaddaq, Aasam; Stone, Tom; Rodriguez, Jon; Slutsker, Ilya; Eck, Tom; Holben, Brent; hide

    2015-01-01

    In recent years it was proposed to combine AERONET network photometer capabilities with a high precision lunar model used for satellite calibration to retrieve columnar nighttime AODs. The USGS lunar model can continuously provide pre-atmosphere high precision lunar irradiance determinations for multiple wavelengths at ground sensor locations. When combined with measured irradiances from a ground-based AERONET photometer, atmospheric column transmissions can determined yielding nighttime column aerosol AOD and Angstrom coefficients. Additional demonstrations have utilized this approach to further develop calibration methods and to obtain data in polar regions where extended periods of darkness occur. This new capability enables more complete studies of the diurnal behavior of aerosols, and feedback for models and satellite retrievals for the nighttime behavior of aerosols. It is anticipated that the nighttime capability of these sensors will be useful for comparisons with satellite lidars such as CALIOP and CATS in additional to ground-based lidars in MPLNET at night, when the signal-to-noise ratio is higher than daytime and more precise AOD comparisons can be made.

  16. Comparison of Photometer with Improved Neubauer Hemocytometer and Makler Counting Chamber for Sperm Concentration Measurement in Cattle

    Directory of Open Access Journals (Sweden)

    Naima Atiq, Nemat Ullah1*, S. M. H. Andrabi2 and Shamim Akhter

    2011-01-01

    Full Text Available The present study was designed to compare the photometer (Lp 300 SDM Minitüb GmHb with improved Neubauer hemocytometer and Makler counting chamber for sperm concentration measurement in cow bulls. Data were based on 35 cow bull semen samples. The average sperm concentrations (109/ml determined by photometer, hemocytometer and Makler chamber were 1.35±0.72, 1.17±0.53 and 1.49±0.60, respectively. Analysis of variance revealed that there was no difference among the three techniques of sperm concentration measurement of same semen samples in cow bulls. It was concluded that the use of photometer in semen evaluation for sperm concentration reduced chances of human error and time consumption effectively.

  17. A new method for nocturnal aerosol measurements with a lunar photometer prototype

    Directory of Open Access Journals (Sweden)

    A. Barreto

    2013-03-01

    Full Text Available This paper presents the preliminary results of nocturnal Aerosol Optical Depth (τa and Angström Exponent (α obtained from a new lunar photometer prototype, trade name Cimel CE-318U. Due to the variation of the moon's illumination inherent to the lunar cycle, the typical Langley-plot Method used in solar photometry to calibrate these instruments cannot be applied. In this paper, we propose three different methods to carry out the lunar-photometer calibration. In order to validate the results, we have selected three events which encompass seven nights and ten days under different atmospheric conditions, including several saharan dust intrusions episodes. Method#1 is introduced in this work as a modification of the usual Langley Method. This technique, called Lunar-Langley Method, requires the extraterrestrial irradiances from a lunar irradiance model, providing similar accuracies on τa to those of AERONET (±0.01–0.02. It makes comparable daytime and nighttime measurements. Method#2 consists of transferring the current calibration from a master used by sunphotometers. Its results are again within the limit of accuracy expected for the instrument. Method#3 uses an integrating sphere and the methodology proposed by Li et al. (2008 to determine sky calibration coefficients (Cj and the instrument's solid angle field-of-view (Ω, respectively. We observe significant τa differences between Method#1 and #3 (up to 0.07, which might be attributed to the errors propagation in Method#3. The good results obtained from the comparison against a second CE-318U prototype, and against daytime data from a Precision Filter Radiometer (PFR, constitute a valuable assessment of CE-318U performance. Results of α and its spectral variation (δ α show good agreement between daytime and nighttime, being able to identify the aerosol properties associated with each event.

  18. Application of the SKYRAD Improved Langley plot method for the in situ calibration of CIMEL Sun-sky photometers.

    Science.gov (United States)

    Campanelli, Monica; Estellés, Víctor; Tomasi, Claudio; Nakajima, Teruyuki; Malvestuto, Vincenzo; Martínez-Lozano, José Antonio

    2007-05-10

    The in situ procedure for determining the solar calibration constants, originally developed for the PREDE Sun-sky radiometers and based on a modified version of the Langley plot, was applied to a CIMEL instrument located in Valencia, Spain, not integrated into AERONET. Taking into account the different mechanical and electronic characteristics of the two radiometers, the method was adapted to the characteristics of the CIMEL instrument. The iterative procedure for the determination of the solar calibration constants was applied to a 3-year data set. The results were compared with the two sets of experimental calibration constants determined during this period using the standard Langley plot method. The agreement was found to be consistent with the experimental errors, and the method can definitely also be used to determine the solar calibration constant for the CIMEL instrument, improving its calibration. The method can be used provided the radiometer is previously calibrated for diffuse radiance using a standard lamp.

  19. Analysis of Aerosol Properties in Beijing Based on Ground-Based Sun Photometer and Air Quality Monitoring Observations from 2005 to 2014

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2016-02-01

    Full Text Available Aerosol particles are the major contributor to the deterioration of air quality in China’s capital, Beijing. Using ground-based sun photometer observations from 2005 to 2014, the long-term variations in optical properties and microphysical properties of aerosol in and around Beijing were investigated in this study. The results indicated little inter-annual variations in aerosol optic depth (AOD but an increase in the fine mode AODs both in and outside Beijing. Furthermore, the single scattering albedo in urban Beijing is larger, while observations at the site that is southeast of Beijing suggested that the aerosol there has become more absorbing. The intra-annual aspects were as follow: The largest AOD and high amount of fine mode aerosols are observed in the summer. However, the result of air pollution index (API that mainly affected by the dry density of near-surface aerosol indicated that the air quality has been improving since 2006. Winter and spring were the most polluted seasons considering only the API values. The inconsistency between AOD and API suggested that fine aerosol particles may have a more important role in the deterioration of air quality and that neglecting particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5 in the calculation of API might not be appropriate in air quality evaluation. Through analysis of the aerosol properties in high API days, the results suggested that the fine mode aerosol, especially PM2.5 has become a major contributor to the aerosol pollution in Beijing.

  20. A dedicated H-beta meridian scanning photometer for proton aurora measurement

    Science.gov (United States)

    Unick, Craig W.; Donovan, Eric; Connors, Martin; Jackel, Brian

    2017-01-01

    An instrument designed to measure the location and brightness of auroral emissions from energetic proton precipitation is described. This photometer scans from the north to south horizon with a stepper motor and mirror. The scans are configured in software for a 30 s cadence with equally spaced samples along a meridian at constant altitude. Broadband light is separated into two channels with a novel optical splitter. This splitter uses a filter that has high transmission for the signal channel and high reflection on both the long- and short-wavelength sides to reflect the combined background passbands, directing each channel to its respective detector. The half-cone angle and angle of incidence of this splitter filter allow for an overall compact optical design that also provides superior sensitivity in both signal and background channels. The signal channel is 3 nm wide full width at half maximum (FWHM) at 486.1 nm, and the background channel comprises two 3 nm wide FWHM passbands at 480 nm and 495 nm created by a single filter. Both of these channels are measured with photomultiplier tubes in photon-counting mode. Calibrations indicate a response of around 1000 c/s per rayleigh. Data are currently acquired in 5 ms bins with a Nyquist frequency of 100 Hz. The first system (Forty-Eight Sixty-One (FESO)-1) has been operating at Athabasca University since February 2014, and the second system (FESO-2) was deployed at Lucky Lake, Saskatchewan, in October 2015. The improved sensitivity over legacy instruments and the simultaneous measurement of signal and background enable operation during intervals with dynamic electron aurora and scattered moonlight.

  1. A compact, fast UV photometer for measurement of ozone from research aircraft

    Directory of Open Access Journals (Sweden)

    R. S. Gao

    2012-09-01

    Full Text Available In situ measurements of atmospheric ozone (O3 are performed routinely from many research aircraft platforms. The most common technique depends on the strong absorption of ultraviolet (UV light by ozone. As atmospheric science advances to the widespread use of unmanned aircraft systems (UASs, there is an increasing requirement for minimizing instrument space, weight, and power while maintaining instrument accuracy, precision and time response. The design and use of a new, dual-beam, UV photometer instrument for in situ O3 measurements is described. A polarization optical-isolator configuration is utilized to fold the UV beam inside the absorption cells, yielding a 60-cm absorption length with a 30-cm cell. The instrument has a fast sampling rate (2 Hz at <200 hPa, 1 Hz at 200–500 hPa, and 0.5 Hz at ≥ 500 hPa, high accuracy (3% excluding operation in the 300–450 hPa range, where the accuracy may be degraded to about 5%, and excellent precision (1.1 × 1010 O3 molecules cm−3 at 2 Hz, which corresponds to 3.0 ppb at 200 K and 100 hPa, or 0.41 ppb at 273 K and 1013 hPa. The size (36 l, weight (18 kg, and power (50–200 W make the instrument suitable for many UASs and other airborne platforms. Inlet and exhaust configurations are also described for ambient sampling in the troposphere and lower stratosphere (1000–50 hPa that control the sample flow rate to maximize time response while minimizing loss of precision due to induced turbulence in the sample cell. In-flight and laboratory intercomparisons with existing O3 instruments show that measurement accuracy is maintained in flight.

  2. Enhancement of aerosol characterization using synergy of lidar and sun - photometer coincident observations: the GARRLiC algorithm

    Science.gov (United States)

    Lopatin, A.; Dubovik, O.; Chaikovsky, A.; Goloub, Ph.; Lapyonok, T.; Tanré, D.; Litvinov, P.

    2013-03-01

    Currently most of experiments pursuing comprehensive characterization of atmosphere include coordinated observations by both lidar and radiometers in order to obtain important complimentary information about aerosol properties. The passive observations by radiometers from ground are mostly sensitive to the properties of aerosol in total atmospheric column and have very limited sensitivity to vertical structure of the atmosphere. Such observations are commonly used for measuring aerosol optical thickness and deriving the information about aerosol microphysics including aerosol particles shape, size distribution, and complex refractive index. In a contrast, lidar observations of atmospheric responses from different altitudes to laser pulses emitted from ground are designed to provide accurate profiling of the atmospheric properties. The interpretation of the lidar observation generally relies on some assumptions about aerosol type and loading. Here we present the GARRLiC algorithm (Generalized Aerosol Retrieval from Radiometer and Lidar Combined data) that simultaneously inverts co-incident lidar and radiometer observations and derives a united set of aerosol parameters. Such synergetic retrieval is expected to result in additional enhancements in derived aerosol properties because the backscattering observations by lidar add some sensitivity to the columnar properties of aerosol, while radiometric observations provide sufficient constraints on aerosol type and loading that generally are missing in lidar signals. GARRLiC is based on AERONET algorithm for inverting combined observations by radiometer and multi-wavelength elastic lidar observations. It is expected that spectral changes of backscattering signal obtained by multi-wavelength lidar at different altitudes provide some sensitivity to the vertical variability of aerosol particle sizes. In order to benefit from this sensitivity the algorithm is set to derive not only the vertical profile of total aerosol

  3. Aerosol measurements over Southern Africa using LIDAR, satellite and sun-photometer

    CSIR Research Space (South Africa)

    Sivakumar, V

    2009-08-01

    Full Text Available .O. Box 395, Pretoria 0001, South Africa 2Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Lynwood Road, Pretoria 0002, South Africa Asia Oceania Geosciences Society (AOGS), 11-15 August 2009 3Department of Physics... km Slide 4 © CSIR 2008 www.csir.co.za 2-3 km Data head2right LIDAR (Light Detection and Ranging) Pretoria (25.45 S ; 28.16 E) head2right HYSPLIT NASA head2right AERONET University of Wits (26 S; 28 E) 2002 to 2008...

  4. Aerosol measurements over South Africa using LIDAR, Satellite and Sun Photometer

    CSIR Research Space (South Africa)

    Sivakumar, V

    2010-05-01

    Full Text Available of South Africa. 1. Introduction Aerosols (solid particles suspended in the air) play an important role in the global climate, the radiative forcing of the climate, and the Earth?s radiative balance. The interaction between atmospheric aerosol... pollution as well as from natural processes, such as wind generated dust and sea spray, volcanic eruptions and smoke from natural forest fires, etc. The knowledge of aerosol characteristics at a local and global scale, their temporal change interrelations...

  5. Nocturnal aerosol optical depth measurements with a small-aperture automated photometer using the moon as a light source

    Science.gov (United States)

    Berkoff, T.A.; Sorokin, M.; Stone, T.; Eck, T.F.; Hoff, R.; Welton, E.; Holben, B.

    2011-01-01

    A method is described that enables the use of lunar irradiance to obtain nighttime aerosol optical depth (AOD) measurements using a small-aperture photometer. In this approach, the U.S. Geological Survey lunar calibration system was utilized to provide high-precision lunar exoatmospheric spectral irradiance predictions for a ground-based sensor location, and when combined with ground measurement viewing geometry, provided the column optical transmittance for retrievals of AOD. Automated multiwavelength lunar measurements were obtained using an unmodified Cimel-318 sunphotometer sensor to assess existing capabilities and enhancements needed for day/night operation in NASA's Aerosol Robotic Network (AERONET). Results show that even existing photometers can provide the ability for retrievals of aerosol optical depths at night near full moon. With an additional photodetector signal-to-noise improvement of 10-100, routine use over the bright half of the lunar phase and a much wider range of wavelengths and conditions can be achieved. Although the lunar cycle is expected to limit the frequency of observations to 30%-40% compared to solar measurements, nevertheless this is an attractive extension of AERONET capabilities. ?? 2011 American Meteorological Society.

  6. Nocturnal Aerosol Optical Depth Measurements with a Small-Aperture Automated Photometer Using the Moon as a Light Source

    Science.gov (United States)

    Berkoff, Timothy A.; Sorokin, Mikail; Stone, Tom; Eck, Thomas F.; Hoff, Raymond; Welton, Ellsworth; Holben, Brent

    2011-01-01

    A method is described that enables the use of lunar irradiance to obtain nighttime aerosol optical depth (AOD) measurements using a small-aperture photometer. In this approach, the U.S. Geological Survey lunar calibration system was utilized to provide high-precision lunar exoatmospheric spectral irradiance predictions for a ground-based sensor location, and when combined with ground measurement viewing geometry, provided the column optical transmittance for retrievals of AOD. Automated multiwavelength lunar measurements were obtained using an unmodified Cimel-318 sunphotometer sensor to assess existing capabilities and enhancements needed for day/night operation in NASA s Aerosol Robotic Network (AERONET). Results show that even existing photometers can provide the ability for retrievals of aerosol optical depths at night near full moon. With an additional photodetector signal-to-noise improvement of 10-100, routine use over the bright half of the lunar phase and a much wider range of wavelengths and conditions can be achieved. Although the lunar cycle is expected to limit the frequency of observations to 30%-40% compared to solar measurements, nevertheless this is an attractive extension of AERONET capabilities.

  7. Nocturnal Aerosol Optical Depth Measurements with a Small-Aperture Automated Photometer Using the Moon as a Light Source

    Science.gov (United States)

    Berkoff, Timothy A.; Sorokin, Mikail; Stone, Tom; Eck, Thomas F.; Hoff, Raymond; Welton, Ellsworth; Holben, Brent

    2011-01-01

    A method is described that enables the use of lunar irradiance to obtain nighttime aerosol optical depth (AOD) measurements using a small-aperture photometer. In this approach, the U.S. Geological Survey lunar calibration system was utilized to provide high-precision lunar exoatmospheric spectral irradiance predictions for a ground-based sensor location, and when combined with ground measurement viewing geometry, provided the column optical transmittance for retrievals of AOD. Automated multiwavelength lunar measurements were obtained using an unmodified Cimel-318 sunphotometer sensor to assess existing capabilities and enhancements needed for day/night operation in NASA s Aerosol Robotic Network (AERONET). Results show that even existing photometers can provide the ability for retrievals of aerosol optical depths at night near full moon. With an additional photodetector signal-to-noise improvement of 10-100, routine use over the bright half of the lunar phase and a much wider range of wavelengths and conditions can be achieved. Although the lunar cycle is expected to limit the frequency of observations to 30%-40% compared to solar measurements, nevertheless this is an attractive extension of AERONET capabilities.

  8. Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images

    Science.gov (United States)

    Ramirez, Daniel Perez; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

    2012-01-01

    This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  9. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky-images

    Directory of Open Access Journals (Sweden)

    D. Pérez-Ramírez

    2012-02-01

    Full Text Available This paper present the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. This kind of algorithms is necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, δAe(λ, and precipitable water vapor content, W, at night-time. This cloud screening procedure consists of calculating moving averages of δAe(λ and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable δAe(λ and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  10. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky images

    Directory of Open Access Journals (Sweden)

    D. Pérez-Ramírez

    2012-07-01

    Full Text Available This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, δAe(λ, and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of δAe(λ and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable δAe(λ and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  11. CALIPSO satellite validation using an elastic backscattering Lidar system and the AERONET sun photometer data; Validacao dos dados do satelite CALIPSO utilizando um sistema Lidar de retroespelhamento elastico e o fotometro solar da rede AERONET

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Fabio Juliano da Silva

    2011-07-01

    Aerosol and clouds play an important role in the Earth's climate process through their direct and indirect contributions to the radiation budget. The largest difficulty in predicting the climate change processes is associated with uncertainties in the distribution and properties of aerosols and clouds, as well as their interactions on a global scale. The CALIPSO mission was developed as part of the NASA program, in collaboration with the French space agency CNES, with the main goal to develop studies that will help to quantify the uncertainties about aerosols and clouds. The CALIPSO satellite carried a Lidar system on board, named CALIOP, as a primary instrument, able to provide the aerosol and cloud vertical profiles and distribution, as well as their interactions. Once the optical properties measured by CALIOP are retrieved, using a complex set of algorithms, it is necessary to study and develop methodologies in order to assess the accuracy of the CALIOP products. In this context, a validation methodology was developed in order to verify the assumed values of the Lidar Ratio selected by the CALIOP algorithms, using two ground-based remote sensing instruments, an elastic backscatter Lidar system (MSP) installed at IPEN in Sao Paulo and the AERONET sun photometers operating at five different locations in Brazil, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiaba - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e Sao Paulo - Sao Paulo (SP). Those days when the CALIOP system and ground-based instruments spatially coincided, were selected and analyzed under cloud-free conditions, as well as days when the trajectories of air masses indicated the transport of air parcels from the CALIOP track towards the ground-based sensors. The Lidar Ratio values from the Aeronet/Caliop proposed model was determined and showed good consistency with those initially assumed by the CALIOP Algorithm. Based on the quantitative comparison, a mean difference of

  12. Skylab experiment performance evaluation manual. Appendix T: Experiment T027/S073 contamination measurement, photometer and Gegenschein/zodiacal light (MSFC)

    Science.gov (United States)

    Meyers, J. E.

    1973-01-01

    A series of analyses for Experiment T027/S073, contamination measurement, photometer and gegenschein/zodiacal light (MSFC), to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditons is presented. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.

  13. NitroMAC: An instrument for the measurement of HONO and intercomparison with a long-path absorption photometer.

    Science.gov (United States)

    Afif, Charbel; Jambert, Corinne; Michoud, Vincent; Colomb, Aurélie; Eyglunent, Gregory; Borbon, Agnès; Daële, Véronique; Doussin, Jean-François; Perros, Pascal

    2016-02-01

    NitroMAC (French acronym for continuous atmospheric measurements of nitrogenous compounds) is an instrument which has been developed for the semi-continuous measurement of atmospheric nitrous acid (HONO). This instrument relies on wet chemical sampling and detection using high performance liquid chromatography (HPLC)-visible absorption at 540 nm. Sampling proceeds by dissolution of gaseous HONO in a phosphate buffer solution followed by derivatization with sulfanilamide/N-(1-naphthyl)-ethylenediamine. The performance of this instrument was found to be as follows: a detection limit of around 3 ppt with measurement uncertainty of 10% over an analysis time of 10 min. Intercomparison was made between the instrument and a long-path absorption photometer (LOPAP) during two experiments in different environments. First, air was sampled in a smog chamber with concentrations up to 18 ppb of nitrous acid. NitroMAC and LOPAP measurements showed very good agreement. Then, in a second experiment, ambient air with HONO concentrations below 250 ppt was sampled. While NitroMAC showed its capability of measuring HONO in moderate and highly polluted environments, the intercomparison results in ambient air highlighted that corrections must be made for minor interferences when low concentrations are measured.

  14. Sun

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Sun Microsystems, Inc. is committed to open standards,a standardization system, and sharing within the information tech nology field, focusing not only on technical innovation, but also on new ideas, practices and future development.

  15. System modeling based measurement error analysis of digital sun sensors

    Institute of Scientific and Technical Information of China (English)

    WEI; M; insong; XING; Fei; WANG; Geng; YOU; Zheng

    2015-01-01

    Stringent attitude determination accuracy is required for the development of the advanced space technologies and thus the accuracy improvement of digital sun sensors is necessary.In this paper,we presented a proposal for measurement error analysis of a digital sun sensor.A system modeling including three different error sources was built and employed for system error analysis.Numerical simulations were also conducted to study the measurement error introduced by different sources of error.Based on our model and study,the system errors from different error sources are coupled and the system calibration should be elaborately designed to realize a digital sun sensor with extra-high accuracy.

  16. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP at high black carbon mass concentration levels

    Directory of Open Access Journals (Sweden)

    A.-P. Hyvärinen

    2013-01-01

    Full Text Available The Multi-Angle Absorption Photometer (MAAP is a widely-used instrument for aerosol black carbon (BC measurements. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments characterized by high black carbon concentrations. The artifact occurs after a filter spot change – as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ~3 μg m−3 at the typical MAAP flow rate of 16.7 L min−1 or 1 m3 h−1. The artifact is caused by erroneous dark counts in the photodetector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photodetector raw signals. It was found that, in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m−3 (at the flow rate of 16.7 L min−1 are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 L min−1 and concentration of about 24 μg m−3 (BC accumulation rate ~0.4 μg min−1, the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from

  17. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP) at high black carbon mass concentration levels

    Science.gov (United States)

    Hyvärinen, A.-P.; Vakkari, V.; Laakso, L.; Hooda, R. K.; Sharma, V. P.; Panwar, T. S.; Beukes, J. P.; van Zyl, P. G.; Josipovic, M.; Garland, R. M.; Andreae, M. O.; Pöschl, U.; Petzold, A.

    2013-01-01

    The Multi-Angle Absorption Photometer (MAAP) is a widely-used instrument for aerosol black carbon (BC) measurements. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments characterized by high black carbon concentrations. The artifact occurs after a filter spot change - as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal) is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ~3 μg m-3 at the typical MAAP flow rate of 16.7 L min-1 or 1 m3 h-1. The artifact is caused by erroneous dark counts in the photodetector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photodetector raw signals. It was found that, in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m-3 (at the flow rate of 16.7 L min-1) are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 L min-1 and concentration of about 24 μg m-3 (BC accumulation rate ~0.4 μg min-1), the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from Gual Pahari (India), Beijing (China), and Welgegund (South Africa). In Beijing, the results could also be compared against a

  18. Ozone Standard Reference Photometer

    Data.gov (United States)

    Federal Laboratory Consortium — The Standard Reference Photometer (SRP) Program began in the early 1980s as collaboration between NIST and the U.S. Environmental Protection Agency (EPA) to design,...

  19. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP at high black carbon mass concentration levels

    Directory of Open Access Journals (Sweden)

    A.-P. Hyvärinen

    2012-09-01

    Full Text Available The Multi-Angle Absorption Photometer (MAAP is a widely-used instrument for aerosol black carbon observations. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments with high black carbon concentrations. The artifact occurs after a filter spot change – as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ∼3 μg m−3 at the typical MAAP flow rate of 16.7 l min−1 or 1 m3 h−1. The artifact is caused by erroneous dark counts in the photo detector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photo detector raw signals. It was found that in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m−3 (at the flow rate of 16.7 l min−1 are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 l min−1 and concentration of about 24 μg m−3 (BC accumulation rate ∼0.4 μg min−1, the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from Gual Pahari

  20. MicroCameras and Photometers (MCP) on board TARANIS satellite

    Science.gov (United States)

    Farges, Thomas; Blanc, Elisabeth; Hébert, Philippe; Le Mer-Dachard, Fanny; Ravel, Karen; Gaillac, Stéphanie

    2017-04-01

    TARANIS (Tool for the Analysis of Radiations from lightNings and Sprites) is a CNES micro satellite. Its main objective is to study impulsive transfers of energy between the Earth atmosphere and the space environment. It will be sun-synchronous at an altitude of 700 km. It will be launched from end-2018 for at least 2 years. Its payload is composed of several electromagnetic instruments in different wavelengths (from gamma-rays to radio waves including optical). TARANIS instruments are currently in calibration and qualification phase. The purpose of this poster is to present the MicroCameras and Photometers (MCP) scientific objectives and the sensor design, to show the performances of this instrument using the recent characterization, and at last to promote its products. The MicroCameras, developed by Sodern, are dedicated to the spatial description of TLEs and their parent lightning. They are able to differentiate sprite and lightning thanks to two narrow bands ([757-767 nm] and [772-782 nm]) that provide simultaneous pairs of images of an Event. Simulation results of the differentiation method will be shown. After calibration and tests, the MicroCameras are now delivered to CNES for integration on the payload. The Photometers, developed by Bertin Technologies, will provide temporal measurements and spectral characteristics of TLEs and lightning. There are key instrument because of their capability to detect on-board TLEs and then switch all the instruments of the scientific payload in their high resolution acquisition mode. Photometers use four spectral bands in the [170-260 nm], [332-342 nm], [757-767 nm] and [600-900 nm] and have the same field of view as cameras. The on-board TLE detection algorithm remote-controlled parameters have been tuned before launch using the electronic board and simulated or real events waveforms. The Photometers are now in the calibration and test phase. They will be delivered for integration in mid-2017.

  1. Near-real-time processing of a ceilometer network assisted with sun-photometer data: monitoring a dust outbreak over the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    A. Cazorla

    2017-10-01

    Full Text Available The interest in the use of ceilometers for optical aerosol characterization has increased in the last few years. They operate continuously almost unattended and are also much less expensive than lidars; hence, they can be distributed in dense networks over large areas. However, due to the low signal-to-noise ratio it is not always possible to obtain particle backscatter coefficient profiles, and the vast number of data generated require an automated and unsupervised method that ensures the quality of the profiles inversions. In this work we describe a method that uses aerosol optical depth (AOD measurements from the AERONET network that it is applied for the calibration and automated quality assurance of inversion of ceilometer profiles. The method is compared with independent inversions obtained by co-located multiwavelength lidar measurements. A difference smaller than 15 % in backscatter is found between both instruments. This method is continuously and automatically applied to the Iberian Ceilometer Network (ICENET and a case example during an unusually intense dust outbreak affecting the Iberian Peninsula between 20 and 24 February 2016 is shown. Results reveal that it is possible to obtain quantitative optical aerosol properties (particle backscatter coefficient and discriminate the quality of these retrievals with ceilometers over large areas. This information has a great potential for alert systems and model assimilation and evaluation.

  2. Where do we need additional in situ aerosol and sun photometer data?: a critical examination of spatial biases between MODIS and MISR aerosol products

    Directory of Open Access Journals (Sweden)

    Y. Shi

    2011-07-01

    Full Text Available AErosol RObotic NETwork (AERONET data are the primary benchmark for evaluating satellite retrieved aerosol properties. However, despite its extensive coverage, the representativeness of the AERONET data is rarely discussed. Indeed, many studies have shown that satellite retrieval biases have a significant degree of spatial correlation that may be problematic for higher-level processes or inverse-emissions-modeling studies. To consider these issues and evaluate relative performance in regions of few surface observations, cross-comparisons between the aerosol optical depth (AOD products of operational MODIS Collection 5.1 Dark Target (DT and operational MODIS Collection 5.1 Deep Blue (DB with MISR version 22 were conducted. Through such comparisons, we can observe coherent spatial features of the AOD bias while sidestepping the full analysis required for determining when or where either retrieval is more correct. We identify regions where MODIS to MISR AOD ratios were found to be above 1.3 or below 0.75. Regions where lower boundary condition uncertainty is likely to be a dominant factor include portions of Western North America, the Andes Mountains, Saharan Africa, the Arabian Peninsula, and Central Asia. Similarly, microphysical biases may be an issue in greater South America, and specific parts of Southern Africa, India Asia, East Asia, and Indonesia. These results help identify high-priority locations for possible future deployments of both in situ and ground-based remote sensing measurements. Supplement include GeoTIFF and kml files.

  3. Argos: An Optimized Time-Series Photometer

    Indian Academy of Sciences (India)

    Anjum S. Mukadam; R. E. Nather

    2005-06-01

    We designed a prime focus CCD photometer, Argos, optimized for high speed time-series measurements of blue variables (Nather & Mukadam 2004) for the 2.1 m telescope at McDonald Observatory. Lack of any intervening optics between the primary mirror and the CCD makes the instrument highly efficient.We measure an improvement in sensitivity by a factor of nine over the 3-channel PMT photometers used on the same telescope and for the same exposure time. The CCD frame transfer operation triggered by GPS synchronized pulses serves as an electronic shutter for the photometer. This minimizes the dead time between exposures, but more importantly, allows a precise control of the start and duration of the exposure. We expect the uncertainty in our timing to be less than 100 s.

  4. Differences in aerosol absorption Ångström exponents between correction algorithms for a particle soot absorption photometer measured on the South African Highveld

    Science.gov (United States)

    Backman, J.; Virkkula, A.; Vakkari, V.; Beukes, J. P.; Van Zyl, P. G.; Josipovic, M.; Piketh, S.; Tiitta, P.; Chiloane, K.; Petäjä, T.; Kulmala, M.; Laakso, L.

    2014-12-01

    Absorption Ångström exponents (AAEs) calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example, to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are widely used and are common at aerosol monitoring stations globally. Several correction algorithms are used to account for artefacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are substantial differences between the AAEs calculated from these corrections. Depending on the used correction, AAEs can change by as much as 46%. The study also highlights that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol when using the same data set. The AAE ranged between 1.17 for non-corrected data to 1.96 for the correction that gave the greatest values. Furthermore, the study implies that the AAEs reported for a site depend on at which filter transmittance the filter is changed. In this work, the AAEs were calculated from data measured with a three-wavelength particle soot absorption photometer (PSAP) at Elandsfontein on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals, by a factor of 15. The correlation coefficient between the dilution-corrected PSAP and a non-diluted Multi-Angle Absorption Photometer (MAAP) was 0.9. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites that are not often visited or suffer from high levels of pollution.

  5. Inventory of African desert dust events in the north-central Iberian Peninsula in 2003-2014 based on sun-photometer-AERONET and particulate-mass-EMEP data

    Science.gov (United States)

    Cachorro, Victoria E.; Burgos, Maria A.; Mateos, David; Toledano, Carlos; Bennouna, Yasmine; Torres, Benjamín; de Frutos, Ángel M.; Herguedas, Álvaro

    2016-07-01

    A reliable identification of desert dust (DD) episodes over north-central Spain is carried out based on the AErosol RObotic NETwork (AERONET) columnar aerosol sun photometer (aerosol optical depth, AOD, and Ångström exponent, α) and European Monitoring and Evaluation Programme (EMEP) surface particulate-mass concentration (PMx, x = 10, 2.5, and 2.5-10 µm) as the main core data. The impact of DD on background aerosol conditions is detectable by means of aerosol load thresholds and complementary information provided by HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) air mass back trajectories, MODIS (Moderate Resolution Imaging Spectroradiometer) images, forecast aerosol models, and synoptic maps, which have been carefully reviewed by a human observer for each day included in the DD inventory. This identification method allows the detection of low and moderate DD intrusions and also of mixtures of mineral dust with other aerosol types by means of the analysis of α. During the period studied (2003-2014), a total of 152 DD episodes composed of 418 days are identified. Overall, this means ˜ 13 episodes and ˜ 35 days per year with DD intrusion, representing 9.5 % days year-1. During the identified DD intrusions, 19 daily exceedances over 50 µg m-3 are reported at the surface. The occurrence of DD event days during the year peaks in March and June, with a marked minimum in April and lowest occurrence in winter. A large interannual variability is observed showing a statistically significant temporal decreasing trend of ˜ 3 days year-1. The DD impact on the aerosol climatology is addressed by evaluating the DD contribution in magnitude and percent (in brackets) for AOD, PM10, PM2.5, and PM2.5 - 10, obtaining mean values of 0.015 (11.5 %), 1.3 µg m-3 (11.8 %), 0.55 µg m-3 (8.5 %) and 0.79 µg m-3 (16.1 %), respectively. Annual cycles of the DD contribution for AOD and PM10 present two maxima - one in summer (0.03 and 2.4 µg m-3 for AOD in

  6. Spectrometers for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR): Airborne Concepts and Ground Prototype Measurements

    Science.gov (United States)

    Russell, P. B.; Schmid, B.; Flynn, C.; Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Livingston, J.

    2007-12-01

    calibrated with an integrating sphere, and its performance has been characterized in many tests, including comparisons of its sun-tracking and sky-scanning measurements to AATS-14 and an AERONET Cimel sun-sky photometer, respectively. This poster includes concepts for 4STAR-Air and results of the above 4STAR-Ground measurements.

  7. Studies of propane flame soot acting as heterogeneous ice nuclei in conjunction with single particle soot photometer measurements

    Directory of Open Access Journals (Sweden)

    I. Crawford

    2011-09-01

    Full Text Available The ice nucleation efficiency of propane flame soot particles with and without a sulphuric acid coating was investigated using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and Dynamics in the Atmosphere. The test soot for cloud formation simulations was produced using a propane flame Combustion Aerosol Standard generator (CAST, Jing-CAST Technologies. The organic carbon content (OC of the test soot was altered in a reproducible fashion by changing the fuel/air mixture of the generator. The soot content of ice nuclei was subsequently investigated using a combination of a pumped counterflow virtual impactor (PCVI to separate and evaporate the ice crystals, and a DMT single particle soot photometer (SP2 to examine the mixing state of the BC containing ice residuals.

    Ice nucleation was found to be most efficient for uncoated soot of low organic carbon content (~5 % organic carbon content where deposition freezing occurred at an ice saturation ratio Sice ~ 1.22 at a temperature T = 226.6 K with 25 % of the test soot becoming active as ice nuclei. Propane flame soot of higher organic carbon content (~30 % and ~70 % organic carbon content showed significantly lower ice nucleation efficiency (an activated fraction of the order of a few percent in the experiments than the low organic carbon content soot, with water saturation being required for freezing to occur. Ice nucleation occurred over the range Sice = 1.22–1.70, and T = 223.2–226.6 K. Analysis of the SP2 data showed that the 5 % organic carbon content soot had an undetectable OC coating whereas the 30 % organic carbon content soot had a thicker or less volatile OC coating.

    The application of a sulphuric acid coating to the flame soot shifted the threshold of the onset of freezing towards that of the homogeneous freezing of sulphuric acid; for the minimum OC flame soot this inhibited nucleation since the

  8. Studies of propane flame soot acting as heterogeneous ice nuclei in conjunction with single particle soot photometer measurements

    Directory of Open Access Journals (Sweden)

    I. Crawford

    2011-04-01

    Full Text Available The ice nucleation efficiency of propane flame soot particles with and without a sulphuric acid coating was investigated using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and Dynamics in the Atmosphere. The test soot for cloud formation simulations was produced using a propane flame Combustion Aerosol Standard generator (CAST, Jing-CAST Technologies. The organic carbon content (OC of the test soot was altered in a reproducible fashion by changing the fuel/air mixture of the generator. The soot content of ice nuclei was subsequently investigated using a combination of a pumped counterflow virtual impactor (PCVI to separate and evaporate the ice crystals, and a DMT single particle soot photometer (SP2 to examine the mixing state of the BC containing ice residuals.

    Ice nucleation was found to be most efficient for uncoated soot of low organic carbon content (~5% organic carbon content where deposition freezing occurred at an ice saturation ratio Sice~1.22 at a temperature T = 226.6 K with 25% of the test soot becoming active as ice nuclei. Propane flame soot of higher organic carbon content (~30% and ~70% organic carbon content showed significantly lower ice nucleation efficiency (an activated fraction of the order of a few percent in the experiments than the low organic carbon content soot, with water saturation being required for freezing to occur. Ice nucleation occurred over the range Sice = 1.22–1.70, and T = 223.2–226.6 K. Analysis of the SP2 data showed that the 5% organic carbon content soot had an undetectable OC coating whereas the 30% organic carbon content soot had a thicker or less volatile OC coating.

    The application of a sulphuric acid coating to the flame soot shifted the threshold of the onset of freezing towards that of the homogeneous freezing of sulphuric acid; for the minimum OC flame soot this inhibited nucleation since the onset of

  9. Comparisons of LASE, aircraft, and satellite measurements of aerosol optical properties and water vapor during TARFOX

    NARCIS (Netherlands)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Kooi, S.; Clayton, M.; Hobbs, P.V.; Hartley, S.; Veefkind, J.P.; Russell, P.; Livingston, J.; Tanré, D.; Hignett, P.

    2000-01-01

    We examine aerosol extinction and optical thickness from the Lidar Atmospheric Sensing Experiment (LASE), the in situ nephelometer and absorption photometer on the University of Washington C-131A aircraft, and the NASA Ames Airborne Tracking Sun Photometer (AATS-6) on the C-131A measured during the

  10. Comparisons of LASE, aircraft, and satellite measurements of aerosol optical properties and water vapor during TARFOX

    NARCIS (Netherlands)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Kooi, S.; Clayton, M.; Hobbs, P.V.; Hartley, S.; Veefkind, J.P.; Russell, P.; Livingston, J.; Tanré, D.; Hignett, P.

    2000-01-01

    We examine aerosol extinction and optical thickness from the Lidar Atmospheric Sensing Experiment (LASE), the in situ nephelometer and absorption photometer on the University of Washington C-131A aircraft, and the NASA Ames Airborne Tracking Sun Photometer (AATS-6) on the C-131A measured during the

  11. Temperature-Dependent Refractive Index Measurements of Caf2, Suprasil 3001, and S-FTM16 for the Euclid Near Infrared Spectrometer and Photometer

    Science.gov (United States)

    Leviton, Douglas B.; Miller, Kevin H.; Quijada, Manuel A.; Grupp, Frank D.

    2015-01-01

    Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we measured absolute refractive indices at temperatures from 100 to 310 K at wavelengths from 0.42 to 3.6 microns for CaF2, Suprasil 3001 fused silica, and S-FTM16 glass in support of lens designs for the Near Infrared Spectrometer and Photometer (NISP) for ESA's Euclid dark energy mission. We report absolute refractive index, dispersion (dn/d?), and thermo-optic coefficient (dn/dT) for these materials. In this study, materials from different melts were procured to understand index variability in each material. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. For calcium fluoride (CaF2) and S-FTM16, we compare our current measurements with CHARMS measurements of these materials made in the recent past for other programs. We also compare Suprasil 3001's indices to those of other forms of fused silica we have measured in CHARMS.

  12. Differences in aerosol absorption Ångström exponents between correction algorithms for particle soot absorption photometer measured on South African Highveld

    Directory of Open Access Journals (Sweden)

    J. Backman

    2014-09-01

    Full Text Available Absorption Ångstrom exponents (AAE calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are a widely used method and are commonly used at aerosol monitoring stations globally. Several correction algorithms are used to account for the artifacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are significant differences between the AAEs calculated from these corrections. The study also shows that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol for the same data set. In this work the AAEs were calculated from data measured with a three-wavelength Particle Soot Absorption Photometer (PSAP at Elandsfontein on deployed on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals. The dilution-corrected PSAP showed a good agreement with a non-diluted MAAP. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites are not often visited or suffer from high levels of pollution.

  13. Differences in aerosol absorption Ångström exponents between correction algorithms for particle soot absorption photometer measured on South African Highveld

    Science.gov (United States)

    Backman, J.; Virkkula, A.; Vakkari, V.; Beukes, J. P.; Van Zyl, P.; Josipovic, M.; Piketh, S.; Tiitta, P.; Chiloane, K.; Petäjä, T.; Kulmala, M.; Laakso, L.

    2014-09-01

    Absorption Ångstrom exponents (AAE) calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are a widely used method and are commonly used at aerosol monitoring stations globally. Several correction algorithms are used to account for the artifacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are significant differences between the AAEs calculated from these corrections. The study also shows that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol for the same data set. In this work the AAEs were calculated from data measured with a three-wavelength Particle Soot Absorption Photometer (PSAP) at Elandsfontein on deployed on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals. The dilution-corrected PSAP showed a good agreement with a non-diluted MAAP. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites are not often visited or suffer from high levels of pollution.

  14. Assessing Single Particle Soot Photometer and Integrating Sphere/Integrating Sandwich Spectrophotometer measurement techniques for quantifying black carbon concentration in snow

    Directory of Open Access Journals (Sweden)

    J. P. Schwarz

    2012-11-01

    Full Text Available We evaluate the performance of the Single Particle Soot Photometer (SP2 and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW in quantifying the concentration of refractory black carbon (BC in snow samples. We find that the SP2 can be used to measure BC mass concentration in snow with substantially larger uncertainty (60% than for atmospheric sampling (<30%. Achieving this level of accuracy requires careful assessment of nebulizer performance and SP2 calibration with consideration of the fact that BC in snow can exist in larger sizes than typically observed in the atmosphere. Once these issues are addressed, the SP2 is able to measure the size distribution and mass concentration of BC in the snow. Laboratory comparison of the SP2 and the ISSW revealed significant biases in the estimate of BC concentration from the ISSW when test samples contained dust or non-absorbing particulates. These results suggest that current estimates of BC mass concentration in snow or ice formed from fallen snow using either the SP2 or the ISSW may be associated with significant underestimates of uncertainty.

  15. Improving Solar Soft X-Ray (SXR) Irradiance Results from Broadband Photometers with New SXR Spectral Measurements from a CubeSat

    Science.gov (United States)

    Woods, T. N.; Caspi, A.; Chamberlin, P. C.; Didkovsky, L. V.; Eparvier, F. G.; Jones, A. R.; Mason, J. P.; Moore, C. S.; Solomon, S. C.; Viereck, R. A.

    2016-12-01

    There are four decades of broadband soft X-ray (SXR) measurements, but these measurements cannot directly quantify the varying contributions of emission lines (bound-bound) amongst the thermal radiative recombination (free-bound) and thermal and non-thermal bremsstrahlung (free-free) continua. The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat mission, that was deployed into orbit in May 2016, was designed to directly measure the SXR spectra to improve the understanding of flare energetics and for studying the SXR radiation impacts in Earth's ionosphere. The broadband SXR measurements include the two bands of 1.6-25 keV (0.05-0.8 nm) by the GOES X-Ray Sensor (XRS) since the 1970s and the even broader band of 0.2-12 keV (0.1-7 nm) from several missions, including the Yohkoh Soft X-ray Telescope (SXT, 1991-2001), Student Nitric Oxide Experiment (SNOE, 1998-2002), Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED, 2002-present), the Solar Radiation and Climate Experiment (SORCE, 2003-present), and the Solar Dynamics Observatory (SDO, 2010-present). These broadband SXR measurements have been helpful for resolving some differences between ionosphere models and measurements, but differences remain in understanding solar SXR spectral distribution and atmospheric photoelectron flux. The lack of spectral resolution in the SXR range is thought to be the culprit for most of these disagreements and is thus an underlying motivation for the MinXSS CubeSat mission. The new solar SXR spectra in the range of 0.5 to 30 keV (0.04 - 2.5 nm) from MinXSS, along with how they can improve the accuracy of the broadband SXR photometer measurements, will be presented.

  16. Quadrant to Measure the Sun's Altitude

    Science.gov (United States)

    Windsor, A Morgan, Jr.

    2013-01-01

    The changing altitude of the Sun (either over the course of a day or longer periods) is a phenomenon that students do not normally appreciate. However, the altitude of the Sun affects many topics in disciplines as diverse as astronomy, meteorology, navigation, or horology, such as the basis for seasons, determination of latitude and longitude, or…

  17. Measuring sun exposure in epidemiological studies: Matching the method to the research question.

    Science.gov (United States)

    King, Laura; Xiang, Fan; Swaminathan, Ashwin; Lucas, Robyn M

    2015-12-01

    Sun exposure has risks and benefits for health. Testing these associations requires tools for measuring sun exposure that are feasible and relevant to the time-course of the health outcome. Recent sun exposure, e.g. the last week, is best captured by dosimeters and sun diaries. These can also be used for medium-term sun exposure e.g. over several weeks, but incur a high participant burden. Self-reported data on "typical time outdoors" for working and non-working days, is less detailed and not influenced by day-to-day variation. Over a longer period, e.g. the lifetime, or for particular life stages, proxies of sun exposure, such as latitude of residence or ambient ultraviolet (UV) radiation levels (from satellites or ground-level monitoring) can be used, with additional detail provided by lifetime sun exposure calendars that include locations of residence, usual time outdoors, and detail of sunburn episodes. Objective measures of lifetime sun exposure include microtopography of sun-exposed skin (e.g. using silicone casts) or conjunctival UV autofluorescence. Potential modifiers of the association between sun exposure and the health outcome, such as clothing coverage and skin colour, may also need to be measured. We provide a systematic approach to selecting sun exposure measures for use in epidemiological health research.

  18. 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...

  19. Mixing states of light-absorbing particles measured using a transmission electron microscope and a single-particle soot photometer in Tokyo, Japan

    Science.gov (United States)

    Adachi, Kouji; Moteki, Nobuhiro; Kondo, Yutaka; Igarashi, Yasuhito

    2016-08-01

    Light-absorbing atmospheric aerosols such as carbonaceous particles influence the climate through absorbing sunlight. The mixing states of these aerosol particles affect their optical properties. This study examines the changes in the mixing states and abundance of strongly light absorbing carbonaceous particles by using transmission electron microscopy (TEM) and single-particle soot photometer (SP2), as well as of iron oxide particles, in Tokyo, Japan. TEM and SP2 use fundamentally different detection techniques for the same light-absorbing particles. TEM allows characterization of the morphological, chemical, and structural features of individual particles, whereas SP2 optically measures the number, size, and mixing states of black carbon (BC). A comparison of the results obtained using these two techniques indicates that the peaks of high soot (nanosphere soot (ns-soot)) concentration periods agree with those of the BC concentrations determined by SP2 and that the high Fe-bearing particle fraction periods measured by TEM agree with that of high number concentrations of iron oxide particles measured using SP2 during the first half of the observation campaign. The results also show that the changes in the ns-soot/BC mixing states primarily correlate with the air mass sources, wind speed, precipitation, and photochemical processes. Nano-sized, aggregated, iron oxide particles mixed with other particles were commonly observed by using TEM during the high iron oxide particle periods. We conclude that although further quantitative comparison between TEM and SP2 data will be needed, the morphologically and optically defined ns-soot and BC, respectively, are essentially the same substance and that their mixing states are generally consistent across the techniques.

  20. The Sun lightens and enlightens: high noon shadow measurements

    Science.gov (United States)

    Babović, Vukota; Babović, Miloš

    2014-11-01

    Contemporary physicists and science experts include Eratosthenes’ measurement of the Earth's circumference as one of the most beautiful experiments ever performed in physics. Upon revisiting this famous event in the history of science, we find that some interesting generalizations are possible. On the basis of a rather simple model of the Earth's insolation, we have managed, using some advanced mathematics, to derive a new formula for determining the length of the year, generalized in such a way that it can be used for all planets with sufficiently small eccentricity of the orbit and for all locations with daily sunrises and sunsets. The practical technique that our formula offers is simple to perform, entirely Eratosthenian in spirit, and only requires the angle of the noonday sun to be found on successive days around an equinox. Our results show that this kind of approach to the problem of the Earth's insolation deserves to be included in university courses, especially those which cover astronomy and environmental physics.

  1. Sun behaviour after cutaneous malignant melanoma: a study based on ultraviolet radiation measurements and sun diary data.

    Science.gov (United States)

    Idorn, L W; Datta, P; Heydenreich, J; Philipsen, P A; Wulf, H C

    2013-02-01

    It has been reported that patients with cutaneous malignant melanoma (CMM) can lower their risk of a second primary melanoma by limiting recreational sun exposure. Previous studies based on questionnaires and objective surrogate measurements indicate that before their diagnosis, patients with CMM are exposed to higher ultraviolet radiation (UVR) doses than controls, followed by a reduction after diagnosis. In a prospective, observational case-control study, we aimed to assess sun exposure after diagnosis of CMM by objective measurements to substantiate advice about sun behaviour. The study population consisted of 24 patients recently diagnosed with CMM during the 7 months preceding the start of the study; 51 controls who matched these recently diagnosed patients in age, sex, occupation and constitutive skin type; and 29 patients diagnosed with CMM between 12 months and 6 years before the start of the study. During a summer season participants filled in sun exposure diaries daily and wore personal electronic UVR dosimeters in a wristwatch that continuously measured time-stamped UVR doses in standard erythema dose. The UVR dose of recently diagnosed patients on days with body exposure was one-third lower, and the number of days using sunscreen was double that of matched controls. However, in patients diagnosed more than 12 months earlier, the UVR dose on days with body exposure was one-third higher and the number of days using sunscreen was half that of recently diagnosed patients. Patients with CMM limited their UVR dose on days with body exposure, and by using sunscreen further reduced UVR reaching the skin, although only immediately after diagnosis. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.

  2. Measuring Black Carbon Concentrations in Liquid Samples Using the Single Particle Soot Photometer: Addressing Black Carbon Losses During Sample Storage and Nebulization

    Science.gov (United States)

    Menking, J. A.; Kaspari, S.; Jenkins, M.

    2011-12-01

    Black Carbon (BC), an aerosol created from the incomplete combustion of fossil and bio-fuels, is the second largest contributor to global warming next to CO2. BC deposited on snow and ice reduces the surface albedo, accelerating seasonal snowmelt and glacier retreat and influencing the regional water cycle and climate (Hansen and Nazarenko, 2004). BC emissions and its post-depositional spatial distribution in snow and ice are a large uncertainty in climate change analyses, thus measurements of global BC concentrations in liquid samples of snow and ice are desirable. The Single Particle Soot Photometer (SP2) is a relatively new method for measuring BC concentrations in liquid samples with promising advantages over other commonly used methods, namely that measurements require smaller sample volumes and are not affected by the presence of other absorbing particles. Despite potential advantages over traditional methods, total BC in liquid samples cannot be quantified because of methodological uncertainties. Preliminary tests show BC losses related to (1) nebulization and (2) changes to the sample during storage. BC in storage may adhere to the vial walls, resulting in BC losses. Particles containing BC may also agglomerate to form large particles with sizes outside of the SP2 detection range (80-650nm). Further losses are indicated in a comparison of polydisperse Aquadag (BC standard) particle size distributions between the ultrasonic nebulizer and a collision-type atomizer, which shows a loss of particles > ~500nm associated with the Cetac U-5000AT+ ultrasonic nebulizer. Larger particles may not be nebulized because of inefficiencies related to the ultrasonic transducer plate, and/or highly charged particles may adhere to the glass within the nebulizer, also resulting in BC losses. The purpose of this study was to determine the methods of storage and nebulization that maximize the amount of BC delivered to the SP2 inlet. Storage and sample parameters tested include

  3. Initial performance of the High Speed Photometer

    Science.gov (United States)

    Richards, Evan; Percival, Jeff; Nelson, Matt; Hatter, ED; Fitch, John; White, Rick

    1991-01-01

    The Hubble Space Telescope High Speed Photometer has four image dissector tubes, two with UV sensitive photocathodes, two sensitive to the near UV and to visual light, and a single red sensitive photomultiplier tube. The HSP is capable of photometric measurements from 1200 to 7500 A with time resolution of 11 microseconds and has no moving parts. An initial analysis of the on-orbit engineering performance of the HSP is presented with changes in operating procedures resulting from the primary mirror spherical aberration and experience gained during the verification period.

  4. Novel approach to analysing large data sets of personal sun exposure measurements.

    Science.gov (United States)

    Blesić, Suzana M; Stratimirović, Đorđe I; Ajtić, Jelena V; Wright, Caradee Y; Allen, Martin W

    2016-11-01

    Personal sun exposure measurements provide important information to guide the development of sun awareness and disease prevention campaigns. We assess the scaling properties of personal ultraviolet radiation (pUVR) sun exposure measurements using the wavelet transform (WT) spectral analysis to process long-range, high-frequency personal recordings collected by electronic UVR dosimeters designed to measure erythemal UVR exposure. We analysed the sun exposure recordings of school children, farmers, marathon runners and outdoor workers in South Africa, and construction workers and work site supervisors in New Zealand. We found scaling behaviour in all the analysed pUVR data sets. We found that the observed scaling changes from uncorrelated to long-range correlated with increasing duration of sun exposure. Peaks in the WT spectra that we found suggest the existence of characteristic times in sun exposure behaviour that were to some extent universal across our data set. Our study also showed that WT measures enable group classification, as well as distinction between individual UVR exposures, otherwise unattainable by conventional statistical methods.

  5. Study of Modis satellite derived aerosol angstrom exponent and in-situ measured values using Sun photometer in part of the west coast of Indian Peninsula

    Digital Repository Service at National Institute of Oceanography (India)

    SunilKumar R.K.; Suresh, T.; Govindaraju; SureshKumar, B.V.

    The aerosol angstrom exponent (AAE) is often used as a qualitative indicator of aerosol particle size. It is important to understand and quantify the microphysical impact of aerosols which are derived from natural and anthropogenic activities...

  6. Mejora de la calidad de las medidas de ozono mediante un fotómetro UV de referencia Improvement of the quality of the ozone measurements by means of a standard reference photometer

    Directory of Open Access Journals (Sweden)

    R. Fernández Patier

    2001-11-01

    Full Text Available La Directiva 92/72/CE hace referencia al método de análisis descrito en la UNE 77-221:2000 y a que los analizadores de ozono se deben calibrar con un fotómetro UV de referencia o con un patrón transferido.De la necesidad de desarrollar un procedimiento que asegure la calidad y la trazabilidad de las mediciones en España, el Área de Contaminación Atmosférica ha decidido implantar un fotómetro UV de referencia NIST como patrón de ozono.Teniendo en cuenta los procedimientos empleados por EPA y NIST, se ha desarrollado un procedimiento de verificación consistente en la realización de 6 comparaciones del Patrón Transferido frente al Fotómetro UV de Referencia NIST, en días diferentes, analizándose, como mínimo, 5 concentraciones de ozono diferentes. Cada comparación se inicia y se finaliza siempre con una concentración de 0 ppb de O3. De cada comparación se obtiene una regresión lineal.Una vez realizadas las 6 comparaciones se obtiene la Recta de calibración y se calcula la incertidumbre asociada al patrón transferido.Se ha realizado la verificación de 17 patrones transferidos de los que 11 son fotómetros UV, 2 son generadores de ozono y 4 son generadores de ozono de bancos de dilución.De los resultados se concluye que las incertidumbres de los generadores de ozono, en general, son mayores que las de los fotómetros UV, recomendándose estos últimos como patrones transferidos.Destacar que mediante la utilización de los patrones transferidos para la calibración de analizadores de ozono se garantiza tanto la calidad como la trazabilidad de los datos generados.The Directive 92/72/CE makes reference to the analysis method described in the UNE 77-221:2000 and to the fact that the ozone analyzers shall be calibrated with a UV reference photometer or with a transfer standard.From the need of developing a procedure that assure the quality and the trazability of the measurements in Spain, the Atmospheric Pollution Area has decided

  7. Neutrino measurements from the Sun and Earth: Results from Borexino

    Energy Technology Data Exchange (ETDEWEB)

    Bellini, G.; Caccianiga, B.; D’Angelo, D.; Giammarchi, M.; Lombardi, P.; Ludhova, L.; Meroni, E.; Miramonti, L.; Ranucci, G., E-mail: gioacchino.ranucci@mi.infn.it; Re, A. [Dipartimento di Fisica, Universitá degli Studi e INFN, 20133 Milano (Italy); Benziger, J. [Chemical Engineering Department, Princeton University, Princeton, New Jersey 08544 (United States); Bick, D.; Hagner, C.; Meyer, M. [Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg (Germany); Bonfini, G.; Cavalcante, P.; Gabriele, F.; Gazzana, S.; Ianni, Aldo; Laubenstein, M. [INFN Laboratori Nazionali del Gran Sasso, 67100 Assergi (Italy); and others

    2015-07-15

    Important neutrino results came recently from Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. The recently achieved breakthrough observation of the fundamental pp flux, the precise measurement of the {sup 7}Be solar neutrino flux, and the results concerning the pep, {sup 8}B and CNO fluxes, together with their physics implications, are described in this work. Moreover, the detector has also provided a clean detection of terrestrial neutrinos, from which they emerge as a new probe of the interior of the Earth.

  8. Measurement of the Average Molecular Weight of Cotton Cellulose Crosslinked by a Polycarboxylic Acid at Different pH Using Multiple Angle Light Scattering Photometer in a DMAc/LiCl Solvent System

    Institute of Scientific and Technical Information of China (English)

    MAO Zhi-ping(毛志平); YANG Charles Q

    2003-01-01

    Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength.Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics.Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules.Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization.In this research,a multiple angle laser light scattering photometer was used to determine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0.5 M NaOH solution at 50℃ for 144 h.The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.

  9. Interdependence and contributions of sun exposure and vitamin D to MRI measures in multiple sclerosis.

    Science.gov (United States)

    Zivadinov, Robert; Treu, Cierra N; Weinstock-Guttman, Bianca; Turner, Caitlin; Bergsland, Niels; O'Connor, Kerri; Dwyer, Michael G; Carl, Ellen; Ramasamy, Deepa P; Qu, Jun; Ramanathan, Murali

    2013-10-01

    To assess the relationships of sun exposure history, supplementation and environmental factors to vitamin D levels in multiple sclerosis (MS) patients and to evaluate the associations between sun exposure and MRI measures. This study included 264 MS patients (mean age 46.9±10 years, disease duration 14.6±10 years; 67.8% relapsing-remitting, 28% secondary progressive and 4.2% primary progressive MS) and 69 healthy controls. Subjects underwent neurological and 3 T MRI examinations, provided blood samples and answered questions to a structured questionnaire. Information on race, skin and eye colour, supplement use, body mass index (BMI) and sun exposure was obtained by questionnaire. The vitamin D metabolites (25-hydroxy vitamin D3, 1, 25-dihydroxy vitamin D3 and 24, 25-dihydroxy vitamin D3) were measured using mass spectrometry. Multivitamin supplementation (partial correlation r(p)=0.29, psun exposure (r(p)=0.22, p=0.002) and darker eye colour (r(p)=-0.18, p=0.015) had the strongest associations with vitamin D metabolite levels in the MS group. Increased summer sun exposure was associated with increased grey matter volume (GMV, r(p)=0.16, p=0.019) and whole brain volume (WBV, r(p)=0.20, p=0.004) after correcting for Extended Disability Status Scale in the MS group. Inclusion of 25-hydroxy vitamin D3 levels did not substantially affect the positive associations of sun exposure with WBV (r(p)=0.18, p=0.003) and GMV (r(p)=0.14, p=0.026) in the MS group. Sun exposure may have direct effects on MRI measures of neurodegeneration in MS, independently of vitamin D.

  10. Sun meter

    Science.gov (United States)

    Younskevicius, Robert E.

    1978-01-01

    A simple, inexpensive device for measuring the radiation energy of the sun impinging on the device. The measurement of the energy over an extended period of time is accomplished without moving parts or tracking mechanisms.

  11. Aztec Suns

    Science.gov (United States)

    Petersen, Hugh

    2010-01-01

    The Aztec Sun Stone is a revered Mexican artifact. It is said to be perhaps the most famous symbol of Mexico, besides its flag. It primarily depicts the four great disasters that led to the migration of the Mexica people to modern-day Mexico City. The Aztec Sun Stone also contains pictographs depicting the way the Mexica measured time, and was…

  12. Aztec Suns

    Science.gov (United States)

    Petersen, Hugh

    2010-01-01

    The Aztec Sun Stone is a revered Mexican artifact. It is said to be perhaps the most famous symbol of Mexico, besides its flag. It primarily depicts the four great disasters that led to the migration of the Mexica people to modern-day Mexico City. The Aztec Sun Stone also contains pictographs depicting the way the Mexica measured time, and was…

  13. School Sun-Protection Policies: Measure Development and Assessments in 2 Regions of the United States

    Science.gov (United States)

    Reynolds, Kim D.; Buller, David B.; French, Simone A.; Buller, Mary K.; Ashley, Jeff L.

    2012-01-01

    Background: In 2002, the US Centers for Disease Control and Prevention recommended that schools adopt policies that reduce exposure of children to ultraviolet radiation to prevent skin cancer. We report here the development of a school sun-safety policy measure and baseline descriptive statistics from the assessment of written policies collected…

  14. School Sun-Protection Policies: Measure Development and Assessments in 2 Regions of the United States

    Science.gov (United States)

    Reynolds, Kim D.; Buller, David B.; French, Simone A.; Buller, Mary K.; Ashley, Jeff L.

    2012-01-01

    Background: In 2002, the US Centers for Disease Control and Prevention recommended that schools adopt policies that reduce exposure of children to ultraviolet radiation to prevent skin cancer. We report here the development of a school sun-safety policy measure and baseline descriptive statistics from the assessment of written policies collected…

  15. Continuous Light Absorption Photometer (CLAP) Final Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Jefferson, Anne [National Oceanic and Atmospheric Administration (NOAA), Washington, DC (United States)

    2014-05-01

    The Continuous Light Absorption Photometer (CLAP) measures the aerosol absorption of radiation at three visible wavelengths; 461, 522, and 653 nanometers (nm). Data from this measurement is used in radiative forcing calculations, atmospheric heating rates, and as a prediction of the amount of equivalent black carbon in atmospheric aerosol and in models of aerosol semi-direct forcing. Aerosol absorption measurements are essential to modeling the energy balance of the atmosphere.

  16. Evaluation of the new ESR network software for the retrieval of direct sun products from CIMEL CE318 and PREDE POM01 sun-sky radiometers

    Directory of Open Access Journals (Sweden)

    V. Estellés

    2012-12-01

    Full Text Available The European Skynet Radiometers network (EuroSkyRad or ESR has been recently established as a research network of European PREDE sun-sky radiometers. Moreover, ESR is federated with SKYNET, an international network of PREDE sun-sky radiometers mostly present in East Asia. In contrast to SKYNET, the European network also integrates users of the CIMEL CE318 sky–sun photometer. Keeping instrumental duality in mind, a set of open source algorithms has been developed consisting of two modules for (1 the retrieval of direct sun products (aerosol optical depth, wavelength exponent and water vapor from the sun extinction measurements; and (2 the inversion of the sky radiance to derive other aerosol optical properties such as size distribution, single scattering albedo or refractive index. In this study we evaluate the ESR direct sun products in comparison with the AERosol RObotic NETwork (AERONET products. Specifically, we have applied the ESR algorithm to a CIMEL CE318 and PREDE POM simultaneously for a 4-yr database measured at the Burjassot site (Valencia, Spain, and compared the resultant products with the AERONET direct sun measurements obtained with the same CIMEL CE318 sky–sun photometer. The comparison shows that aerosol optical depth differences are mostly within the nominal uncertainty of 0.003 for a standard calibration instrument, and fall within the nominal AERONET uncertainty of 0.01–0.02 for a field instrument in the spectral range 340 to 1020 nm. In the cases of the Ångström exponent and the columnar water vapor, the differences are lower than 0.02 and 0.15 cm, respectively. Therefore, we present an open source code program that can be used with both CIMEL and PREDE sky radiometers and whose results are equivalent to AERONET and SKYNET retrievals.

  17. Evaluation of the new ESR network software for the retrieval of direct sun products from CIMEL CE318 and PREDE POM01 sun-sky radiometers

    Science.gov (United States)

    Estellés, V.; Campanelli, M.; Smyth, T. J.; Utrillas, M. P.; Martínez-Lozano, J. A.

    2012-12-01

    The European Skynet Radiometers network (EuroSkyRad or ESR) has been recently established as a research network of European PREDE sun-sky radiometers. Moreover, ESR is federated with SKYNET, an international network of PREDE sun-sky radiometers mostly present in East Asia. In contrast to SKYNET, the European network also integrates users of the CIMEL CE318 sky-sun photometer. Keeping instrumental duality in mind, a set of open source algorithms has been developed consisting of two modules for (1) the retrieval of direct sun products (aerosol optical depth, wavelength exponent and water vapor) from the sun extinction measurements; and (2) the inversion of the sky radiance to derive other aerosol optical properties such as size distribution, single scattering albedo or refractive index. In this study we evaluate the ESR direct sun products in comparison with the AERosol RObotic NETwork (AERONET) products. Specifically, we have applied the ESR algorithm to a CIMEL CE318 and PREDE POM simultaneously for a 4-yr database measured at the Burjassot site (Valencia, Spain), and compared the resultant products with the AERONET direct sun measurements obtained with the same CIMEL CE318 sky-sun photometer. The comparison shows that aerosol optical depth differences are mostly within the nominal uncertainty of 0.003 for a standard calibration instrument, and fall within the nominal AERONET uncertainty of 0.01-0.02 for a field instrument in the spectral range 340 to 1020 nm. In the cases of the Ångström exponent and the columnar water vapor, the differences are lower than 0.02 and 0.15 cm, respectively. Therefore, we present an open source code program that can be used with both CIMEL and PREDE sky radiometers and whose results are equivalent to AERONET and SKYNET retrievals.

  18. The deflection of light induced by the Sun's gravitational field and measured with geodetic VLBI

    CERN Document Server

    Titov, O

    2015-01-01

    The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only during total Solar eclipses. Geodetic Very Long Baseline Interferometry (VLBI) is capable of measuring the deflection of the light from distant radio sources anytime and across the whole sky. We show that the effect of light deflection is equivalent to the gravitational delay calculated during the reduction of VLBI data. All reference radio sources display an annual circular motion with the magnitude proportional to their ecliptic latitude. In particular, radio sources near the ecliptic pole draw an annual circle with magnitude of 4 mas. This effect could be easily measured with the current precision of the geodetic VLBI data.

  19. PROCESSING METHOD EFFECT ON SUN DIAMETER MEASUREMENT WITH CCD SOLAR ASTROLABE

    Energy Technology Data Exchange (ETDEWEB)

    Djafer, Djelloul [Unite de Recherche Appliquee en Energies Renouvelables, BP 88, Ghardaiea (Algeria); Irbah, Abdenour, E-mail: djdjafer@gmail.com, E-mail: abdenour.irbah@latmos.ipsl.fr [Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS), CNRS UMR8190, Universite Paris VI, Pierre et Marie Curie, Universite de Versailles Saint-Quentin-en-Yvelines INSU, 78280 Guyancourt (France)

    2012-05-01

    Photometric Sun diameter measurement is based on the calculation of the inflection point of the solar limb. In ground measurement, this point is located at a position on the solar limb where the signal-to-noise ratio is very high, which necessitates the appropriate filtering techniques to eliminate the noise while preserving its position. In this paper, we compare the filtering method currently in use to process the CCD solar astrolabe data, the FFTD method widely used, with a different method that we propose. Using the acquired data from the CCD astrolabe at Calern, France during 1997, we can obtain a mean difference of 130 mas in the measured radii.

  20. Quiet Sun Magnetic Field Measurements Based on Lines with Hyperfine Structure

    CERN Document Server

    Almeida, J Sanchez; Degl'Innocenti, E Landi; Berrilli, F

    2007-01-01

    The Zeeman pattern of MnI lines is sensitive to hyperfine structure (HFS) and, they respond to hG magnetic field strengths differently from the lines used in solar magnetometry. This peculiarity has been employed to measure magnetic field strengths in quiet Sun regions. However, the methods applied so far assume the magnetic field to be constant in the resolution element. The assumption is clearly insufficient to describe the complex quiet Sun magnetic fields, biasing the results of the measurements. We present the first syntheses of MnI lines in realistic quiet Sun model atmospheres. The syntheses show how the MnI lines weaken with increasing field strength. In particular, kG magnetic concentrations produce NnI 5538 circular polarization signals (Stokes V) which can be up to two orders of magnitude smaller than the weak magnetic field approximation prediction. Consequently, (1) the polarization emerging from an atmosphere having weak and strong fields is biased towards the weak fields, and (2) HFS features c...

  1. MicroCameras and Photometers (MCP) instrument on board TARANIS satellite: scientific objectives, design, characterization results and products

    Science.gov (United States)

    Farges, T.; Hébert, P.; Le Mer-Dachard, F.; Cansot, E.; Offroy, M.; Ravel, K.; Gaillac, S.; Sato, M.; Blanc, E.

    2015-12-01

    TARANIS (Tool for the Analysis of Radiations from lightNings and Sprites) is a CNES micro satellite. Its main objective is to study impulsive transfers of energy between the Earth atmosphere and the space environment. It will be sun-synchronous at an altitude of 700 km. It will be launched from late 2017 for at least 2 years. Its payload is composed of several electromagnetic instruments in different wavelengths (from gamma-rays to radio waves including optical). TARANIS instruments are currently in calibration and qualification phase. The purpose of this poster is to present the MicroCameras and Photometers (MCP) scientific objectives and the sensor design, to show the performances of this instrument using the recent characterization, and at last to promote its products. The MicroCameras, developed by Sodern, are dedicated to the spatial description of TLEs and their parent lightning. They are able to differentiate sprite and lightning thanks to two narrow bands ([757-767 nm] and [772-782 nm]) that provide simultaneous pairs of images of an Event. The calibration results will be detailed. Simulation results of the differentiation method will be shown. Photometers, developed by Bertin Technologies, will provide temporal measurements and spectral characteristics of TLEs and lightning. It is a key instrument because of its on-board detection of the TLEs which can trigger the whole payload. Photometers use four spectral bands in the [170-260 nm], [332-342 nm], [757-767 nm] and [600-900 nm] and have the same field of view as cameras. The calibration results will also be detailed. The on-board TLE detection algorithm remote-controlled parameters will be tuned before launch using the electronic board and simulated or real events waveforms. Automatic classification tools are now tested to produce for the Scientific Mission Center some lists of elves, sprites or lightning without TLE following the recent work of Offroy et al. [2015] using ISUAL spectrophotometer data.

  2. Portable fluorescence photometer for monitoring free calcium

    Science.gov (United States)

    Struckmeier, Jens; Klopp, Erk; Born, Matthias; Hofmann, Martin; Tenbosch, Jochen; Jones, David B.

    2000-12-01

    We introduce a compact and portable photometric system for measurements of the calcium dynamics in cells. The photometer is designed for applications in centrifuges or in zero gravity environment and thus extremely compact and reliable. It operates with the calcium-sensitive dye Indo-1. The excitation wavelength of 345 nm is generated by frequency doubling of a laser diode. Two compact photomultiplier tubes detect the fluorescent emission. The electronics provide the sensitivity of photon counting combined with simultaneous measurement of the temperature, of air pressure, and of gravitational force. Internal data storage during the experiment is possible. A newly developed cell chamber stabilizes the cell temperature to 37.0±0.1 °C and includes a perfusion system to supply the cells with medium. The system has a modular setup providing the possibility of changing the light source and detectors for investigation of ions other than calcium. Measurements of the intracellular calcium concentration are based on a comprehensive calibration of our system. First experiments show that the calcium dynamics of osteosarcoma cells stimulated by parathyroid hormone is observable.

  3. Theoretical model and quantification of reflectance photometer

    Institute of Scientific and Technical Information of China (English)

    Lihua Huang; Youbao Zhang; Chengke Xie; Jianfeng Qu; Huijie Huang; Xiangzhao Wang

    2009-01-01

    @@ The surface morphology of lateral flow (LF) strip is examined by scanning electron microscope (SEM) and the diffuse reflection of porous strip with or without nanogold particles is investigated.Based on the scattering and absorption of nanogold particles, a reflectance photometer is developed for quantification of LF strip with nanogold particles as reporter.The integration of reflection optical density is to indicate the signals of test line and control line.As an example, serial dilutions of microalbunminuria (MAU) solution are used to calibrate the performance of the reflectance photometer.The dose response curve is fitted with a four-parameter logistic mathematical model for the determination of an unknown MAU concentration.The response curve spans a dynamic range of 5 to 200 μg/ml.The developed reflectance photometer can realize simple and quantitative detection of analyte on nanogold-labeled LF strip.

  4. Midnight sun

    Energy Technology Data Exchange (ETDEWEB)

    Brunger, A.P.; Lambert, S.B.; Gagnon, M.P.

    1990-09-01

    Midnight Sun, the University of Waterloo's solar-electric car, was designed and built by about 30 engineering, kinesiology and physics students for the GM Sunrayce USA held in July 1990. The car measures 2 m by 4.2 m, weighs 224 kg, can collect about 1000 W of solar electricity in full sun, and had a top speed of 79 km/h. The race took 11 days to cover the 1644 miles from the Epcot Center in Lake Buena Vista, Florida to the GM Technical Center in Warren, Michigan. Thirty-two cars, powered only by solar energy, competed in this race. Midnight Sun showed its potential during the race qualifying runs by completing the required qualifying course with the 12th fastest time of 52.83 seconds, and the 6th fastest trap speed of 63 km/h. During the Sunrayce, Midnight Sun came in second on day 1 of the race, tenth on day 6, and eighth on day 7, and was one of only 17 solar cars that were able to make it up the toughest hill in the race on day 8. The most serious problems encountered by the car were a weak rear suspension, power losses, and failure of bypass diodes in the photovoltaic array. Midnight Sun was in 17th place overall at the end of day 9. At about 11:00 am on day 10 in Ohio, the Waterloo car was moving at 60 km/h when it was bumped off the road by an out of control pickup truck. The solar car driver was not hurt. Despite the difficulties, the next day Midnight Sun was repaired and driven across the finish line at the ceremonial finish. After receiving time penalties for not completing the last day and a half of the race, Midnight Sun was awarded 24th place with an official cumulative time of 114 h 37 min 15 s. 4 figs., 4 tabs.

  5. Relationship between interferon regulatory factor 4 genetic polymorphisms, measures of sun sensitivity and risk for non-Hodgkin lymphoma.

    Science.gov (United States)

    Gathany, Allison H; Hartge, Patricia; Davis, Scott; Cerhan, James R; Severson, Richard K; Cozen, Wendy; Rothman, Nathaniel; Chanock, Stephen J; Wang, Sophia S

    2009-10-01

    Sun exposure and sensitivity, including pigmentation, are associated with risk for non-Hodgkin lymphoma (NHL). One variant in the immune regulatory factor 4 (IRF4) gene (rs12203592) is associated with pigmentation, and a different IRF4 variant (rs12211228) is associated with NHL risk. We evaluated the independent roles of these IRF4 polymorphisms and sun sensitivity in mediating NHL risk and explored whether they are confounded or modified by each other. Genotyping of tag single nucleotide polymorphisms (SNPs) in the IRF4 gene was conducted in 990 NHL cases and 828 controls from a multi-center US study. Measures of sun sensitivity and exposure were ascertained from computer-assisted personal interviews. We used logistic regression to compute odds ratios (OR) and 95% confidence intervals (CI) for NHL in relation to sun exposures, sun exposures in relation to IRF4 genotypes, and NHL in relation to sun exposures. We further assessed the effects of sun exposures in relation to IRF4 genotypes. As previously reported, we found significant associations between IRF4 rs12211228 and NHL and between hair and eye color and NHL. The IRF4 rs12203592 polymorphism (CT/TT genotype) was statistically significantly associated with eye color and particularly with hair color (OR(Light Blonde) = 0.24, 95% CI = 0.11-0.50, overall Chi square p = 0.0002). Analysis of joint effects between eye and hair color with the IRF4 rs12203592 SNP did not reveal statistically significant p-interactions although NHL risk did decline with lighter hair color and presence of the variant IRF4 rs12203592 allele, compared to those without a variant allele and with black/brown hair color. Our data do not statistically support a joint effect between IRF4 and sun sensitivity in mediating risk for NHL. Further evaluation of joint effects in other and larger populations is warranted.

  6. Coronal Thermal Structure from a Differential Emission Measure Map of the Sun

    Science.gov (United States)

    Cook, J. W.; Newmark, J. S.; Moses, J. D.

    1999-10-01

    We have developed a procedure to produce a differential emission measure (DEM) map of the Sun using images from the four channels of the EIT instrument at 171 (Fe IX/X), 195 (Fe XII), 284 (Fe XV), and 304 A (He II). We use images from the EIT CalRoc sounding rocket flight on 16 October 1997. Our DEM procedure could also be applied to calibrated SOHO EIT images and to TRACE observations. We find a statistical relation between brightness of solar features (for example in the 171 A image) and increasing slope of the DEM in the temperature range log T = 5.5 to 6.0. In their thermal structure active regions are not just areas brighter than quiet areas whose DEM distributions continue to rise to even hotter temperatures, but have greater relative amounts of hotter material to cooler material toward 1 M K and above than do quiet areas. The DEM should not be modeled in terms of an average structure, either plane parallel or with loop geometry. Since at least the time of the SO82A spectroheliograph observations from Skylab it has been clear that structures observed in the temperature range of any one line differ from structures observed in a hotter or cooler line. Any DEM distribution is obtained from intensity observations through all structures in the line of sight, and is composed from the combined individual DEM distributions of these structures. We interpret the DEM map in terms of ensembles of individual loops of differing temperatures, where the ensembles are characteristically different in quiet and active areas of the Sun. This work is supported by NASA under DPR S-92385-D and by the Office of Naval Research.

  7. A fibre optic, four channel comparative photometer

    Science.gov (United States)

    Walker, E. N.

    1988-01-01

    Development of a four channel comparative photometer is described. Tests have shown that it is stable from night to night and is capable of working in very poor sky conditions. Even when the sky conditions are so poor that stars are barely visible, light curves can still be obtained with an r.m.s. value of 0.0016 mag., provided that integration times that are long compared with the transparancy changes are possible.

  8. Coordinated airborne, spaceborne, and ground-based measurements of massive thick aerosol layers during the dry season in southern Africa

    NARCIS (Netherlands)

    Schmid, B.; Redemann, J.; Russell, P.B.; Hobbs, P.V.; Hlavka, D.L.; McGill, M.J.; Holben, B.N.; Welton, E.J.; Campbell, J.R.; Torres, O.; Kahn, R.A.; Diner, D.J.; Helmlinger, M.C.; Chu, D.A.; Robles-Gonzalez, C.; Leeuw, G.de

    2003-01-01

    During the dry season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), coordinated observations were made of massive thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sun photometer measurements of aero

  9. Coordinated airborne, spaceborne, and ground-based measurements of massive thick aerosol layers during the dry season in southern Africa

    NARCIS (Netherlands)

    Schmid, B.; Redemann, J.; Russell, P.B.; Hobbs, P.V.; Hlavka, D.L.; McGill, M.J.; Holben, B.N.; Welton, E.J.; Campbell, J.R.; Torres, O.; Kahn, R.A.; Diner, D.J.; Helmlinger, M.C.; Chu, D.A.; Robles-Gonzalez, C.; Leeuw, G.de

    2003-01-01

    During the dry season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), coordinated observations were made of massive thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sun photometer measurements of

  10. Characterization and intercomparison of aerosol absorption photometers: result of two intercomparison workshops

    Directory of Open Access Journals (Sweden)

    T. Müller

    2011-02-01

    Full Text Available Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs and Aethalometers. Multi Angle Absorption Photometers (MAAPs showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.

  11. Low-cost photometers and open source software for Light Pollution research

    Science.gov (United States)

    Zamorano, Jaime; Nievas, Miguel; Sánchez de Miguel, Alejandro; Tapia, Carlos; García, Cristóbal; Pascual, Sergio; Ocaña, Francisco; Gallego, Jesús

    2015-08-01

    Astronomical observatories have been measuring the brightness of the sky (NSB) using the methods of astronomical photometry with telescopes, photoelectric photometers and CCD cameras. The observations are disperse and sporadic. This is why some dedicated devices (including all-sky cameras) have been designed to automatically monitor the sky brightness at the observatories.These sophisticated and expensive instruments are restricted to research groups since they are out of reach for the interested citizens who wish to make a contribution to light pollution research. Most of them are using sky photometers (sky quality meter, SQM) a commercial photometer, designed to measure NSB in a photometric band that mimics the human eye response, that provide reliable data at an affordable budget.We are designing and building low cost devices to measure night sky brightness that could be widely distributed. The final designs will be calibrated and distributed to the community as open hardware. The researchers and also the interested people could acquire the parts and replicate the photometers from the instructions provided. Among the new features for these photometers we plan to add the capability to automatically send data to a repository located in a server, the autonomous operation with solar panels and batteries in remote places and the ability to measure in different spectral bands.We also present open source software for NSB research. PySQM, designed for SQM photometers, records the NSB data in the IDA-IAU standard data format and also builds the plots along the night. PyASB analyses all-sky images to determine photometric parameters and to build all-sky NSB maps

  12. PACS photometer calibration block analysis

    CERN Document Server

    Moór, A; Kiss, Cs; Balog, Z; Billot, N; Marton, G

    2013-01-01

    The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5% (standard deviation) or about 8% peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements by a fixed and time-independent response file, without using any information from the PACS internal calibration sources. However, the analysis of calibration block observations revealed clear correlations of the internal source signals with the evaporator temperature and a signal drift during the first half hour after the cooler recycling. These effects are small, but can be seen in repeated measurements of standard stars. From our analysis we established corrections for both effects which push the stability of the PACS bolometer response to about 0.2% (stdev) or 2% in the blue, 3% in the green and 5% in the red channel (peak-to-peak). After both corrections we still see a correlation of the signals with PACS FPU temperatures, possibly caused by parasitic h...

  13. Spaceborne Sun-Induced Vegetation Fluorescence Time Series from 2007 to 2015 Evaluated with Australian Flux Tower Measurements

    NARCIS (Netherlands)

    Sanders, Abram; Verstraeten, Willem; Kooreman, Maurits; Leth, Van Thomas; Beringer, Jason; Joiner, Joanna

    2016-01-01

    A global, monthly averaged time series of Sun-induced Fluorescence (SiF), spanning January 2007 to June 2015, was derived from Metop-A Global Ozone Monitoring Experiment 2 (GOME-2) spectral measurements. Far-red SiF was retrieved using the filling-in of deep solar Fraunhofer lines and atmospheric ab

  14. Measuring sun exposure habits and sun protection behaviour using a comprehensive scoring instrument--an illustration of a possible model based on Likert scale scorings and on estimation of readiness to increase sun protection.

    Science.gov (United States)

    Falk, M; Anderson, C D

    2012-08-01

    Few attempts to present a comprehensive scoring instrument for sun exposure and protection have been made. The present paper aims to describe a possible set of questions suitable for such an instrument, comprising the most important aspects of sun exposure and protection. The material from a previously performed intervention study, using a questionnaire based on Likert scales and on the Transtheoretical Model of Behaviour Change (TTM), was utilised. 213 primary healthcare patients filled in the questionnaire and were randomised into two groups receiving sun protection advice, in Group 1 in letter-form, and in Group 2 orally during a doctor's consultation. In the original study, increased sun protection/readiness to increase sun protection was demonstrated for several items in Group 2, at six months. To compose a comprehensive scoring instrument, five questions concerning sun exposure/protection (intentional tanning, sunscreen use, choice of SPF, number of occasions with sunburn, and time spent in the sun at midday), were selected to give a 20 point behavioural score. Similarly, four TTM-based questions (giving up sunbathing, using clothes for sun protection, using sunscreens, and staying in the shade) gave a 16 point "propensity-to-change"-score. At follow-up, increased sun protection reflected in the behavioural score occurred only in Group 2 (p Likert scale behavioural score with a TTM-based propensity-to-change-score seems promising for the creation of a questionnaire-based, comprehensive scoring instrument for sun exposure and protection. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. The Mount Wilson Observatory S-index of the Sun

    Science.gov (United States)

    Egeland, Ricky; Soon, Willie; Baliunas, Sallie; Hall, Jeffrey C.; Pevtsov, Alexei A.; Bertello, Luca

    2017-01-01

    The most commonly used index of stellar magnetic activity is the instrumental flux scale of singly ionized calcium H & K line core emission, S, developed by the Mount Wilson Observatory (MWO) HK Project, or the derivative index {R}{HK}\\prime . Accurately placing the Sun on the S scale is important for comparing solar activity to that of the Sun-like stars. We present previously unpublished measurements of the reflected sunlight from the Moon using the second-generation MWO HK photometer during solar cycle 23 and determine cycle minimum {S}23,\\min =0.1634+/- 0.0008, amplitude {{Δ }}{S}23=0.0143+/- 0.0012, and mean =0.1701+/- 0.0005. By establishing a proxy relationship with the closely related National Solar Observatory Sacramento Peak calcium K emission index, itself well correlated with the Kodaikanal Observatory plage index, we extend the MWO S time series to cover cycles 15–24 and find on average =0.1621+/- 0.0008, =0.0145+/- 0.0012, =0.1694+/- 0.0005. Our measurements represent an improvement over previous estimates that relied on stellar measurements or solar proxies with non-overlapping time series. We find good agreement from these results with measurements by the Solar-Stellar Spectrograph at Lowell Observatory, an independently calibrated instrument, which gives us additional confidence that we have accurately placed the Sun on the S-index flux scale.

  16. MIPS - The Multiband Imaging Photometer for SIRTF

    Science.gov (United States)

    Rieke, G. H.; Lada, C.; Lebofsky, M.; Low, F.; Strittmatter, P.; Young, E.; Beichman, C.; Gautier, T. N.; Mould, J.; Werner, M.

    1986-01-01

    The Multiband Imaging Photometer System (MIPS) for SIRTF is to be designed to reach as closely as possible the fundamental sensitivity and angular resolution limits for SIRTF over the 3 to 700 microns spectral region. It will use high performance photoconductive detectors from 3 to 200 microns with integrating JFET amplifiers. From 200 to 700 microns, the MIPS will use a bolometer cooled by an adiabatic demagnetization refrigerator. Over much of its operating range, the MIPS will make possible observations at and beyond the conventional Rayleigh diffraction limit of angular resolution.

  17. SphinX: The Solar Photometer in X-Rays

    Science.gov (United States)

    Gburek, Szymon; Sylwester, Janusz; Kowalinski, Miroslaw; Bakala, Jaroslaw; Kordylewski, Zbigniew; Podgorski, Piotr; Plocieniak, Stefan; Siarkowski, Marek; Sylwester, Barbara; Trzebinski, Witold; Kuzin, Sergey V.; Pertsov, Andrey A.; Kotov, Yurij D.; Farnik, Frantisek; Reale, Fabio; Phillips, Kenneth J. H.

    2013-04-01

    Solar Photometer in X-rays (SphinX) was a spectrophotometer developed to observe the Sun in soft X-rays. The instrument observed in the energy range ≈ 1 - 15 keV with resolution ≈ 0.4 keV. SphinX was flown on the Russian CORONAS-PHOTON satellite placed inside the TESIS EUV and X telescope assembly. The spacecraft launch took place on 30 January 2009 at 13:30 UT at the Plesetsk Cosmodrome in Russia. The SphinX experiment mission began a couple of weeks later on 20 February 2009 when the first telemetry dumps were received. The mission ended nine months later on 29 November 2009 when data transmission was terminated. SphinX provided an excellent set of observations during very low solar activity. This was indeed the period in which solar activity dropped to the lowest level observed in X-rays ever. The SphinX instrument design, construction, and operation principle are described. Information on SphinX data repositories, dissemination methods, format, and calibration is given together with general recommendations for data users. Scientific research areas in which SphinX data find application are reviewed.

  18. The Hetu'u Global Network: Measuring the Distance to the Sun with the Transit of Venus

    Science.gov (United States)

    Rodriguez, David; Faherty, J.

    2013-01-01

    In the spirit of historic astronomical endeavors, we invited school groups across the globe to collaborate in a solar distance measurement using the 2012 transit of Venus. In total, our group (stationed at Easter Island, Chile) recruited 19 school groups spread over 6 continents and 10 countries to participate in our Hetu’u Global Network. Applying the methods of French astronomer Joseph-Nicolas Delisle, we used individual second and third Venus-Sun contact times to calculate the distance to the Sun. Ten of the sites in our network had amiable weather; 8 of which measured second contact and 5 of which measured third contact leading to consistent solar distance measurements of 152+/-30 million km and 163+/-30 million km respectively. The distance to the Sun at the time of the transit was 152.25 million km; therefore, our measurements are also consistent within 1-sigma of the known value. The goal of our international school group network was to inspire the next generation of scientists using the excitement and accessibility of such a rare astronomical event. In the process, we connected hundreds of participating students representing a diverse, multi-cultural group with differing political, economic, and racial backgrounds.

  19. Correlations and linkages between the sun and the earth's atmosphere: Needed measurements and observations

    Science.gov (United States)

    Kellogg, W. W.

    1975-01-01

    A study was conducted to identify the sequence of processes that lead from some change in solar input to the earth to a change in tropospheric circulation and weather. Topics discussed include: inputs from the sun, the solar wind, and the magnetosphere; bremsstrahlung, ionizing radiation, cirrus clouds, thunderstorms, wave propagation, and gravity waves.

  20. Transferring the calibration of direct solar irradiance to diffuse-sky radiance measurements for CIMEL Sun-sky radiometers.

    Science.gov (United States)

    Li, Zhengqiang; Blarel, Luc; Podvin, Thierry; Goloub, Philippe; Buis, Jean-Pierre; Morel, Jean-Philippe

    2008-04-01

    Two types of sunphotometric measurement are considered in this study: direct-Sun irradiance and diffuse-sky radiance. Based on CIMEL CE318 Sun-sky radiometer characteristics, we introduce a gain-corrected solid angle that allows interconverting calibration coefficients of these two types of measurement, thus realizing a "vicarious" radiance calibration. The accuracy of the gain-corrected solid angle depends on the number of available historical calibration records. The method is easy to use, provided that at least one laboratory calibration has been made previously. Examples coming from three distinct CE318 versions belonging to the AERONET/PHOTONS network are presented to provide details on the vicarious calibration method and protocols. From the error propagation analysis and the comparison with laboratory results, the uncertainty of the vicarious radiance calibration is shown to be comparable with the laboratory one, e.g., 3%-5%.

  1. The assessment and characterization of the built-in internal photometer of primary diagnostic monitors.

    Science.gov (United States)

    Ruuge, Andres E; Mahmood, Usman A; Erdi, Yusuf E

    2017-03-01

    The purpose of this work was to perform the initial evaluation of primary diagnostic monitor (PDM) characteristics following the implementation of New York City quality assurance (NYC QA) regulations on January 1, 2016, and compare the results of the QA measurements performed by an external photometer and the PDM manufacturer's built-in photometer. TG-18 and Society of Motion Picture and Television Engineers test patterns were used to evaluate monitor performance. Overall, 79 PDMs were included in the analysis. The verification of grayscale standard display function (GSDF) calibration, using a built-in photometer, showed that only 2 out of 79 PDMs failed calibration. However, the same measurements performed by the external luminance meter showed that 15 out of 79 monitors had failed GSDF calibration. Measurements of the PDMs maximum luminance (Lmax ), using an external photometer showed that 10 out of 53 PDMs calibrated for Lmax = 400 cd/m(2) and 17 out of 26 PDMs calibrated for Lmax = 500 cd/m(2) do not meet the manufacturer's recommended 10% tolerance limit for the target Lmax calibration. Two PDMs did not pass the Lmax ≥ 350 cd/m(2) NYC QA regulations with Lmax = 331 cd/m(2) and Lmax = 340 cd/m(2) . All tested PDMs exceeded the minimum luminance ratio (LR) of 250:1 as required by NYC QA regulations. Measurements taken of Lmax and LR performed by a built-in photometer showed that none of the PDMs had failed the NYC QA regulations. All PDMs passed the luminance uniformity test with a maximum nonuniformity of 17% (according to NYC regulations it must be less than 30%). The luminance uniformity test could only be performed using an external photometer. The evaluation of 79 PDMs of various ages and models demonstrated up to 18% disagreement between luminance measurements performed by the manufacturer's built-in photometer when compared with those performed by an externally calibrated luminance meter. These disagreements were larger for older PDMs. © 2017 The

  2. Sun Allergy

    Science.gov (United States)

    ... if you have unusual, bothersome skin reactions after exposure to sunlight. For severe or persistent symptoms, you may need ... m. when the sun is brightest. Avoid sudden exposure to lots of sunlight. Many people have sun allergy symptoms when they ...

  3. The Orbiting Carbon Observatory (OCO-2: spectrometer performance evaluation using pre-launch direct sun measurements

    Directory of Open Access Journals (Sweden)

    C. Frankenberg

    2014-07-01

    Full Text Available The Orbiting Carbon Observatory-2 (OCO-2, launched on 2 July 2014, is a NASA mission designed to measure the column-averaged CO2 dry air mole fraction, XCO2. Towards that goal, it will collect spectra of reflected sun-light in narrow spectral ranges centered at 0.76, 1.6 and 2.0 μm with a resolving power (λ/Δ λ of 20 000. These spectra will be used in an optimal estimation framework to retrieve XCO2. About 100 000 cloud free soundings of XCO2 each day will allow estimates of net CO2 fluxes on regional to continental scales to be determined. Here, we evaluate the OCO-2 spectrometer performance using pre-launch data acquired during instrument thermal vacuum tests in April 2012. A heliostat and a diffuser plate were used to feed direct sunlight into the OCO-2 instrument and spectra were recorded. These spectra were compared to those collected concurrently from a nearby high-resolution Fourier Transform Spectrometer that was part of the Total Carbon Column Observing Network (TCCON. Using the launch-ready OCO-2 calibration and spectroscopic parameters, we performed total column scaling fits to all spectral bands and compared these to TCCON results. On 20 April, we detected a CO2 plume from the Los Angeles basin at the JPL site with strongly enhanced short-term variability on the order of 1% (3–4 ppm. We also found good (2. The variations in spectral fitting residuals are consistent with signal-to-noise estimates from instrument calibration, while average residuals are systematic and mostly attributable to remaining errors in our knowledge of the CO2 and O2 spectroscopic parameters. A few remaining inconsistencies observed during TVAC may be attributable to the specific instrument setup on the ground and will be re-evaluated with in-orbit data, when the instrument is expected to be in a much more stable environment.

  4. OPTIMA A Photon Counting High-Speed Photometer

    CERN Document Server

    Straubmeier, C; Schrey, F

    2001-01-01

    OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed lightcurve of the Crab Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design of the detector system focussing on the photon counting units and the software control which correlates the detected photons with the GPS timing signal.

  5. Auroral meridian scanning photometer calibration using Jupiter

    Science.gov (United States)

    Jackel, Brian J.; Unick, Craig; Creutzberg, Fokke; Baker, Greg; Davis, Eric; Donovan, Eric F.; Connors, Martin; Wilson, Cody; Little, Jarrett; Greffen, M.; McGuffin, Neil

    2016-10-01

    Observations of astronomical sources provide information that can significantly enhance the utility of auroral data for scientific studies. This report presents results obtained by using Jupiter for field cross calibration of four multispectral auroral meridian scanning photometers during the 2011-2015 Northern Hemisphere winters. Seasonal average optical field-of-view and local orientation estimates are obtained with uncertainties of 0.01 and 0.1°, respectively. Estimates of absolute sensitivity are repeatable to roughly 5 % from one month to the next, while the relative response between different wavelength channels is stable to better than 1 %. Astronomical field calibrations and darkroom calibration differences are on the order of 10 %. Atmospheric variability is the primary source of uncertainty; this may be reduced with complementary data from co-located instruments.

  6. Optical properties of aerosol mixtures derived from sun-sky radiometry during SAMUM-2

    Energy Technology Data Exchange (ETDEWEB)

    Toledano, C. (Meteorological Institute, Ludwig-Maximilians-Universitaet, Munich (Germany); Group of Atmospheric Optics, Valladolid Univ., Valladolid (Spain)), e-mail: toledano@goa.uva.es; Wiegner, M.; Gross, S. (Meteorological Institute, Ludwig-Maximilians-Universitaet, Munich (Germany)) (and others)

    2011-09-15

    The SAMUM-2 experiment took place in the Cape Verde islands in January-February 2008. The colocated ground-based and airborne instruments allow the study of desert dust optical and microphysical properties in a closure experiment. The Meteorological Institute of the Univ. of Munich deployed one sun-sky photometer and two tropospheric lidar systems. A travelling AERONET-Cimel sun-sky radiometer was also deployed. During the measurement period the aerosol scenario over Cape Verde mostly consisted of a dust layer below 2 km and a smoke-dust layer above 2-4 km a.s.l. The Saharan dust arrived at the site from the NE, whereas the smoke originated in the African equatorial region. This paper describes the main results of the Sun photometer observations, supported by lidar information. An analysis of the variations in the aerosol optical depth (AOD) in the range 340-1550 nm, the Aangstroem exponent, volume size distributions and single scattering albedo is presented. The aerosol mixtures are analysed by means of the fine mode fraction of the AOD provided by the sun-sky inversion data and the Spectral Deconvolution Algorithm. The mean AOD (500 nm) was 0.31, with associated low Aangstroem exponent of 0.46. Several types of events were detected within the data set, with prevalence of dust or mixtures as characterized by the Aangstroem exponents of extinction and absorption and the fine mode fraction. Aerosol properties derived from sunphotometry were compared to in situ measurements of size distribution, effective radius and single scattering albedo

  7. MIPS - The Multiband Imaging Photometer for SIRTF. [Multiband Imaging Photometer for SIRTF

    Science.gov (United States)

    Rieke, G. H.; Lada, C.; Lebofsky, M.; Low, F.; Strittmatter, P.; Young, E.; Arens, J.; Beichman, C.; Gautier, T. N.; Werner, M.

    1986-01-01

    The Multiband Imaging Photometer for SIRTF (MIPS) is to be designed to reach as closely as possible the fundamental sensitivity and angular resolution limits for SIRTF over the 3 to 700 micron spectral region. It will use high performance photoconductive detectors from 3 to 200 micron with integrating JFET amplifiers. From 200 to 700 microns, the MIPS will use a bolometer cooled by an adiabatic demagnetization refrigerator. Over much of its operating range, the MIPS will make possible observations at and beyond the conventional Rayleigh diffraction limit of angular resolution.

  8. Improved pointing information for SCIAMACHY from in-flight measurements of the viewing directions towards sun and moon

    Science.gov (United States)

    Bramstedt, Klaus; Stone, Thomas C.; Gottwald, Manfred; Noël, Stefan; Bovensmann, Heinrich; Burrows, John P.

    2017-07-01

    The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on Envisat (2002-2012) performed nadir, limb, solar/lunar occultation and various monitoring measurements. The pointing information of the instrument is determined by the attitude information of the Envisat platform with its star trackers together with the encoder readouts of both the azimuth and the elevation scanner of SCIAMACHY. In this work, we present additional sources of attitude information from the SCIAMACHY measurements itself. The basic principle is the same as used by the star tracker: we measure the viewing direction towards celestial objects, i.e. sun and moon, to detect possible mispointings. In sun over limb port observations, we utilise the vertical scans over the solar disk. In horizontal direction, SCIAMACHY's sun follower device (SFD) is used to adjust the viewing direction. Moon over limb port measurements use for both the vertical and the horizontal direction the adjustment by the SFD. The viewing direction is steered towards the intensity centroid of the illuminated part of the lunar disk. We use reference images from the USGS Robotic Lunar Observatory (ROLO) to take into account the inhomogeneous surface and the variations by lunar libration and phase to parameterise the location of the intensity centroid from the observation geometry. Solar observations through SCIAMACHY's so-called sub-solar port (with a viewing direction closely to zenith) also use the SFD in the vertical direction. In the horizontal direction the geometry of the port defines the viewing direction. Using these three type of measurements, we fit improved mispointing parameters by minimising the pointing offsets in elevation and azimuth. The geolocation of all retrieved products will benefit from this; the tangent heights are especially improved. The altitudes assigned to SCIAMACHY's solar occultation measurements are changed in the range of -130 to -330 m, the lunar occultation

  9. Improved pointing information for SCIAMACHY from in-flight measurements of the viewing directions towards sun and moon

    Directory of Open Access Journals (Sweden)

    K. Bramstedt

    2017-07-01

    Full Text Available The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY on Envisat (2002–2012 performed nadir, limb, solar/lunar occultation and various monitoring measurements. The pointing information of the instrument is determined by the attitude information of the Envisat platform with its star trackers together with the encoder readouts of both the azimuth and the elevation scanner of SCIAMACHY. In this work, we present additional sources of attitude information from the SCIAMACHY measurements itself. The basic principle is the same as used by the star tracker: we measure the viewing direction towards celestial objects, i.e. sun and moon, to detect possible mispointings. In sun over limb port observations, we utilise the vertical scans over the solar disk. In horizontal direction, SCIAMACHY's sun follower device (SFD is used to adjust the viewing direction. Moon over limb port measurements use for both the vertical and the horizontal direction the adjustment by the SFD. The viewing direction is steered towards the intensity centroid of the illuminated part of the lunar disk. We use reference images from the USGS Robotic Lunar Observatory (ROLO to take into account the inhomogeneous surface and the variations by lunar libration and phase to parameterise the location of the intensity centroid from the observation geometry. Solar observations through SCIAMACHY's so-called sub-solar port (with a viewing direction closely to zenith also use the SFD in the vertical direction. In the horizontal direction the geometry of the port defines the viewing direction. Using these three type of measurements, we fit improved mispointing parameters by minimising the pointing offsets in elevation and azimuth. The geolocation of all retrieved products will benefit from this; the tangent heights are especially improved. The altitudes assigned to SCIAMACHY's solar occultation measurements are changed in the range of −130 to −330 m, the lunar

  10. Knowledge deficit, attitude and behavior scales association to objective measures of sun exposure and sunburn in a Danish population based sample

    Science.gov (United States)

    Søndergaard, Jens; Nielsen, Jesper Bo; Christensen, Karl Bang; Allen, Martin; Olsen, Anja; Bentzen, Joan

    2017-01-01

    The objective of this study was to develop new scales measuring knowledge and attitude about UVR and sun related behavior, and to examine their association to sun related behavior objectively measured by personal dosimetry. During May-August 2013, 664 Danes wore a personal electronic UV-dosimeter for one week that measured their UVR exposure. Afterwards, they answered a questionnaire on sun-related items. We applied descriptive analysis, linear and logistic regression analysis to evaluate the associations between the questionnaire scales and objective UVR measures. Perceiving protection as routine and important were positively correlated with protective behavior. Knowledge deficit of UV and risk of melanoma, perceived benefits and importance of protection behavior was also correlated with use of protection. ‘Knowledge deficit of UV and risk of melanoma and Perceived barrier towards sun avoidance between 12 and 15’ were both associated with increased risk of sunburn. Attitude towards tan was associated to both outdoor time and exposure as well as use of protection, but not to sunburn. The results regarding Knowledge deficit of UV and risk of melanoma associated to UVR exposure and Perceived barrier towards sun avoidance between 12 and 15 emphasize the importance of awareness of melanoma risk and the priority of the skin cancer prevention advice. Shifting activities to outside the suns peak-hours could be an approach for structural and campaign preventive measures. Knowledge of items predicting exposure to UVR, use of protection and sunburn are important for planning of preventive interventions and melanoma research. PMID:28542543

  11. Evaluation of a Portable Photometer for Estimating Diesel Particulate Matter Concentrations in an Underground Limestone Mine

    OpenAIRE

    Watts, Winthrop F.; Gladis, David D.; Schumacher, Matthew F.; Ragatz, Adam C.; David B. Kittelson

    2010-01-01

    A low cost, battery-operated, portable, real-time aerosol analyzer is not available for monitoring diesel particulate matter (DPM) concentrations in underground mines. This study summarizes a field evaluation conducted at an underground limestone mine to evaluate the potential of the TSI AM 510 portable photometer (equipped with a Dorr-Oliver cyclone and 1.0-μm impactor) to qualitatively track time-weighted average mass and elemental, organic, and total carbon (TC) measurements associated wit...

  12. The Mount Wilson Observatory S-index of the Sun

    CERN Document Server

    Egeland, Ricky; Baliunas, Sallie; Hall, Jeffrey C; Pevtsov, Alexei A; Bertello, Luca

    2016-01-01

    The most commonly used index of stellar magnetic activity is the instrumental flux scale of singly-ionized calcium H & K line core emission, S, developed by the Mount Wilson Observatory (MWO) HK Project, or the derivative index R'_HK. Accurately placing the Sun on the S scale is important for comparing solar activity to that of the Sun-like stars. We present previously unpublished measurements of the reflected sunlight from the Moon using the second-generation MWO HK photometer during solar cycle 23 and determine cycle minimum S_min,23 = 0.1634 +/- 0.0008, amplitude Delta S_23 = 0.0143 +/- 0.0015, and mean = 0.1701 +/- 0.0005. By establishing a proxy relationship with the closely related National Solar Observatory Sacramento Peak calcium K emission index, itself well-correlated with the Kodaikanal Observatory plage index, we extend the MWO S time series to cover cycles 15-24 and find on average = 0.1621 +/- 0.0008, = 0.0145 +/- 0.0012, = 0.1694 +/- 0.0005. Our measurements represent an improvement ove...

  13. NIP: the near infrared imaging photometer for Euclid

    Science.gov (United States)

    Schweitzer, Mario; Bender, Ralf; Katterloher, Reinhard; Eisenhauer, Frank; Hofmann, Reiner; Saglia, Roberto; Holmes, Rory; Krause, Oliver; Rix, Hans-Walter; Booth, Jeff; Fagrelius, Parker; Rhodes, Jason; Seshadri, Suresh; Refregier, Alexandre; Amiaux, Jerome; Augueres, Jean-Louis; Boulade, Olivier; Cara, Christophe; Amara, Adam; Lilly, Simon; Atad-Ettedgui, Eli; di Giorgio, Anna-Maria; Duvet, Ludovic; Kuehl, Christopher; Syed, Mohsin

    2010-07-01

    The NIP is a near infrared imaging photometer that is currently under investigation for the Euclid space mission in context of ESA's 2015 Cosmic Vision program. Together with the visible camera (VIS) it will form the basis of the weak lensing measurements for Euclid. The NIP channel will perform photometric imaging in 3 near infrared bands (Y, J, H) covering a wavelength range from ~ 0.9 to 2 μm over a field of view (FoV) of ~ 0.5 deg2. With the required limiting point source magnitude of 24 mAB (5 sigma) the NIP channel will be used to determine the photometric redshifts of over 2 billion galaxies collected over a wide survey area of 20 000 deg2. In addition to the photometric measurements, the NIP channel will deliver unique near infrared (NIR) imaging data over the entire extragalactic sky, enabling a wide variety of ancillary astrophysical and cosmological studies. In this paper we will present the results of the study carried out by the Euclid Imaging Consortium (EIC) during the Euclid assessment phase.

  14. The Sun

    CERN Document Server

    Golub, Leon

    2017-01-01

    Essential for life on earth and a major influence on our environment, the Sun is also the most fascinating object in the daytime sky. Every day we feel the effect of its coming and going – literally the difference between day and night. But figuring out what the Sun is, what it’s made of, why it glows so brightly, how old it is, how long it will last – all of these take thought and observation. Leon Golub and Jay M. Pasachoff offer an engaging and informative account of what scientists know about the Sun, and the history of these discoveries. Solar astronomers have studied the Sun over the centuries both for its intrinsic interest and in order to use it as a laboratory to reveal the secrets of other stars. The authors discuss the surface of the Sun, including sunspots and their eleven-year cycle, as well as the magnetism that causes them; the Sun’s insides, as studied mainly from seismic waves that astronomers record on its surface; the outer layers of the Sun that we see from Earth only at eclipses ...

  15. Knowledge deficit, attitude and behavior scales association to objective measures of sun exposure and sunburn in a Danish population based sample

    DEFF Research Database (Denmark)

    Køster, Brian; Søndergaard, Jens; Nielsen, Jesper Bo

    2017-01-01

    The objective of this study was to develop new scales measuring knowledge and attitude about UVR and sun related behavior, and to examine their association to sun related behavior objectively measured by personal dosimetry. During May-August 2013, 664 Danes wore a personal electronic UV......-dosimeter for one week that measured their UVR exposure. Afterwards, they answered a questionnaire on sun-related items. We applied descriptive analysis, linear and logistic regression analysis to evaluate the associations between the questionnaire scales and objective UVR measures. Perceiving protection as routine...... 12 and 15' were both associated with increased risk of sunburn. Attitude towards tan was associated to both outdoor time and exposure as well as use of protection, but not to sunburn. The results regarding Knowledge deficit of UV and risk of melanoma associated to UVR exposure and Perceived barrier...

  16. A Data Acquisition Program for an Astronomical Photometer

    Science.gov (United States)

    Bergey, N. A.; Hawkins, R. L.; Ellsworth, C. C.; Caton, D. B.

    2005-12-01

    Recently an astronomical photometer was built for use on the 32-inch telescope Appalachian State University's Dark Sky Observatory (DSO). We have written a first version of the software needed to interpret and display the photometer's output in real time. Primary uses for the photometer are standard star photometry, and continuation of our eclipsing binary research when the nearest comparison star is out of the field of view of our CCD cameras. Eventually high-speed photometry will be added the functionality for transient events such as asteroidal occultations. The program is intended to have the ability to be used with all of our other research telescopes at DSO. Goals for this program include gathering and logging photometry data, real time graphing, filter wheel control, and an easy user interface. The code is being developed with the Microsoft(c) Visual Basic .NET framework with C# as the source code.

  17. Little Sun

    DEFF Research Database (Denmark)

    Ebbesen, Toke Riis

    2017-01-01

    the ideas of Alfred Gell’s anthropology of art and the indicative framework derived from Argentinian semiotician Juan Pablo Bonta and Jørn Guldberg. The toy-like solar lamp Little Sun by Olafur Eliasson and Frederik Ottesen is used as case that blends the registers of social design and art......, and as an example of how designers attempt to determine meaning potentials through design in a complex interplay of different strategies. In the final analysis, what characterise objects like Little Sun is seldom that they communicate their meanings in themselves, but instead rely on forceful mediations to gain...

  18. Little sun

    DEFF Research Database (Denmark)

    Ebbesen, Toke Riis

    2017-01-01

    the ideas of Alfred Gell’s anthropology of art and the indicative framework derived from Argentinian semiotician Juan Pablo Bonta and Jørn Guldberg. The toy-like solar lamp Little Sun by Olafur Eliasson and Frederik Ottesen is used as case that blends the registers of social design and art......, and as an example of how designers attempt to determine meaning potentials through design in a complex interplay of different strategies. In the final analysis, what characterise objects like Little Sun is seldom that they communicate their meanings in themselves, but instead rely on forceful mediations to gain...

  19. The validated sun exposure questionnaire

    DEFF Research Database (Denmark)

    Køster, B; Søndergaard, J; Nielsen, J B

    2017-01-01

    Few questionnaires used in monitoring sun-related behavior have been tested for validity. We established criteria validity of a developed questionnaire for monitoring population sun-related behavior. During May-August 2013, 664 Danes wore a personal electronic UV-dosimeter for one week...... that measured the outdoor time and dose of erythemal UVR exposure. In the following week, they answered a questionnaire on their sun-related behavior in the measurement week. Outdoor time measured by dosimetry correlated strongly with both outdoor time and the developed exposure scale measured....... The weekly sunburn fraction correlated strongly with the number of ambient sun hours (r=0.73, p

  20. A 3-channel CCD photometer at the Xinglong Observatory

    Institute of Scientific and Technical Information of China (English)

    Yong-Na Mao; Xiao-Meng Lu; Jian-Feng Wang; Xiao-Jun Jiang

    2013-01-01

    We describe the design and construction of a new rapid 3-channel CCD photometer,dedicated to simultaneous multicolor photometric observations of rapidly variable objects.This photometer is equipped on the 1-meter telescope at the Xinglong Observatory.It allows simultaneous imaging within fields of view of 18.8' × 18.8',18.2' × 17.6' and 9.2' × 9.2' in the Sloan Digital Sky Survey's g',r' and i' bands,respectively.The results of its calibration and performance are reported.

  1. Assessment of error in aerosol optical depth measured by AERONET due to aerosol forward scattering

    Science.gov (United States)

    Sinyuk, Alexander; Holben, Brent N.; Smirnov, Alexander; Eck, Thomas F.; Slutsker, Ilya; Schafer, Joel S.; Giles, David M.; Sorokin, Mikhail

    2012-12-01

    We present an analysis of the effect of aerosol forward scattering on the accuracy of aerosol optical depth (AOD) measured by CIMEL Sun photometers. The effect is quantified in terms of AOD and solar zenith angle using radiative transfer modeling. The analysis is based on aerosol size distributions derived from multi-year climatologies of AERONET aerosol retrievals. The study shows that the modeled error is lower than AOD calibration uncertainty (0.01) for the vast majority of AERONET level 2 observations, ∼99.53%. Only ∼0.47% of the AERONET database corresponding mostly to dust aerosol with high AOD and low solar elevations has larger biases. We also show that observations with extreme reductions in direct solar irradiance do not contribute to level 2 AOD due to low Sun photometer digital counts below a quality control cutoff threshold.

  2. Measurements of NO{sub 2} using MAX-DOAS observations of sun-illuminated targets

    Energy Technology Data Exchange (ETDEWEB)

    Javed, Umar; Kirk, Henning; Richter, Andreas; Schoenhardt, Anja; Wittrock, Folkard; Burrows, John P. [Institut fuer Umweltphysik, Universitaet Bremen (Germany)

    2009-07-01

    Nitrogen oxide radicals (NO+NO{sub 2}) are important trace gases in the atmosphere. They originate from combustion processes, lightning and soil emissions and largely control the tropospheric ozone production Since several decades it is possible to measure NO{sub 2} with different techniques. However, for the spatial distribution in the troposphere considerable uncertainty exists. Here we present measurements of NO{sub 2} on and close to the campus of the University of Bremen applying a novel technique: Topographic Target Light scattering Differential Optical Absorption Spectroscopy (ToTaL-DOAS, Frins et al.). The basic idea is to collect scattered sunlight reflected from natural and artificial targets (e.g. high buildings) at different distances from the measuring device. Then recorded spectra are analyzed for NO{sub 2} applying the DOAS method. Simple geometric treatments of the light-path reveal NO{sub 2} concentrations in the boundary layer as a final data set. This study presents NO{sub 2} data in 2008 in the surrounding of the University of Bremen. In addition for some days the ZARM Drop Tower has been used as illuminated target to investigate the vertical distribution of NO{sub 2}. Selected data sets have been compared to complementary measurements of the regular iup Bremen MAX-DOAS setup and to the Bremian BLUES air pollution network.

  3. Analysis of aerosol optical properties from continuous sun-sky radiometer measurements at Halley and Rothera, Antarctica over seven years

    Science.gov (United States)

    Campanelli, Monica; Estellés, Victor; Colwell, Steve; Shanklin, Jonathan; Ningombam, Shantikumar S.

    2015-04-01

    The Antarctic continent is located far from most anthropogenic emission sources on the planet, it has limited areas of exposed rock and human activities are less developed. Air circulation over Antarctica also seems to prevent the direct transport of air originating from anthropogenic sources of pollution at lower latitudes. Therefore Antarctica is considered an attractive site for studying aerosol properties as unaltered as possible by human activity. Long term monitoring of the optical and physical properties is necessary for observing possible changes in the atmosphere over time and understanding if such changes are due to human activity or natural variation. Columnar aerosol optical and physical properties can be obtained from sun-sky radiometers, very compact instruments measuring spectral direct and diffuse solar irradiance at the visible wavelengths and using fast and efficient inversion algorithms. The British Antarctic Survey has continuously operated two Prede Pom-01 sun-sky radiometers in Antarctica as part of the ESR-European Skynet Radiometers network (www.euroskyrad.net, Campanelli et al, 2012). They are located at Halley and Rothera, and have operated since 2009 and 2008 respectively. In the present study the aerosol optical thickness, single scattering albedo, Ångström exponent, volume size distribution and refractive index were retrieved from cloud-screened measurements of direct and diffuse solar irradiance using the Skyrad 4.2 pack code (Nakajima et al., 1986). The analysis of the daily and yearly averages showed an important increase of the absorbing properties of particles at Halley from 2013 to the beginning of 2014 related to the increasing presence of smaller particles (from 2012) but with a non-significant variation of aerosol optical depth. The same increase of absorption was visible at Rothera only in 2013. Air pressure measurements, wind directions and intensity, and vertical profiles from radio-soundings, together with HYSPLIT model

  4. Sun Proof

    Centers for Disease Control (CDC) Podcasts

    2012-10-23

    In this podcast for kids, the Kidtastics talk about the harmful effects of the sun and how to protect yourself from it.  Created: 10/23/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 10/23/2012.

  5. Using KD(asterisk)P modulators for polarization measurements of the sun

    Science.gov (United States)

    West, E. A.

    1990-01-01

    Longitudinal KD(asterisk)Ps are used in ground-based solar magnetographs to eliminate seeing effects by rapidly changing their retardation characteristics. Although one of the main applications for longitudinal KD(asteriak)Ps has been their use as a variable retarder for 'imaging' applications, an understanding of their limitations is important when developing scientific instruments that make very accurate polarization measurements. This paper discusses some of the problems associated with the use of these devices in the Marshall Space Flight Center (MSFC) vector magnetograph, including temperature, field of view errors, and electrical characteristics.

  6. A Performance Comparison for Two Versions of the Vulcan Photometer

    Science.gov (United States)

    Borucki, W. J.; Caldwell, D. A.; Koch, D. G.; Jenkins, J. M.; Showen, R. L.

    2001-01-01

    Analysis of the images produced by the first version (V1) of the Vulcan photometer indicated that two major sources of noise were sky brightness and image motion. To reduce the effect of the sky brightness, a second version (V2) with a longer focal length and a larger format detector was developed and tested. The first version consisted of 15-centimeter (cm) focal length, F/1.5 Aerojet Delft reconnaissance lens, and a 2048 x 2048 format front-illuminated charged coupled device (CCD) with 9 microns micropixels (Mpixels). The second version used a 30-cm focal length, F/2.5 Kodak AeroEktar lens, and a 4096 x 4096 format CCD with 9 micro pixels. Both have a 49-square-degree field of view (FOV) but the area of the sky subtended by each pixel in the V2 version is one-fourth that of the V1 version. This modification substantially reduces the shot noise due to the sky background and allows fainter stars to be monitored for planetary transits. To remove the data gap and consequent signal-level change caused by flipping the photometer around the declination axis and to reduce image movement on the detector, several other modifications were incorporated. These include modifying the mount and stiffening the photometer and autoguider structures to reduce flexure. This paper compares the performance characteristics of each photometer and discusses tests to identify sources of systematic noise.

  7. Flux calibration of the Herschel(star)-SPIRE photometer

    NARCIS (Netherlands)

    Bendo, G. J.; Griffin, M. J.; Bock, J. J.; Conversi, L.; Dowell, C. D.; Lim, T.; Lu, N.; North, C. E.; Papageorgiou, A.; Pearson, C. P.; Pohlen, M.; Polehampton, E. T.; Schulz, B.; Shupe, D. L.; Sibthorpe, B.; Spencer, L. D.; Swinyard, B. M.; Valtchanov, I.; Xu, C. K.

    2013-01-01

    We describe the procedure used to flux calibrate the three-band submillimetre photometer in the Spectral and Photometric Imaging Receiver instrument on the Herschel Space Observatory. This includes the equations describing the calibration scheme, a justification for using Neptune as the primary cali

  8. Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector

    OpenAIRE

    Smirnov, O. Y.; Agostini, M.; Appel, S; Bellini, G; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cavalcante, P.; Chepurnov, A.; Choi, K; D'Angelo, D.

    2015-01-01

    Neutrino produced in a chain of nuclear reactions in the Sun starting from the fusion of two protons, for the first time has been detected in a real-time detector in spectrometric mode. The unique properties of the Borexino detector provided an oppurtunity to disentangle pp-neutrino spectrum from the background components. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 10$^{5}$ years time scale, and sets...

  9. Pioneer 10 ultraviolet photometer observations of the interplanetary glow at heliocentric distances from 2 to 14 AU

    Science.gov (United States)

    Wu, F. M.; Judge, D. L.; Suzuki, K.; Carlson, R. W.

    1981-01-01

    An analysis is presented of the observed Pioneer 10 interplanetary data from 1972 to 1977, taking into account the interplanetary glow intensity observed by the Pioneer 10 UV photometer at sun-spacecraft distances of 2-14 AU. On the basis of the obtained data, it was determined that the background intensity for the 200-1400 A band pass of the photometer channel is about 40 + or - 10 R, and that the nearby interstellar density is 0.04 + or - 0.91 per ccm for hydrogen and about 0.01 + or - 0.002 per ccm for helium. Accordingly, the He/H number density is about 0.25 at large distances from the sun. The Pioneer 10 spacecraft is leaving the solar system in the downwind direction, while both Pioneer 11 and Voyager will leave in the upwind direction. The combined UV observations of the interplanetary glow will provide accurate results on the physical status of the inflowing interstellar gas and the variability of background radiation as well.

  10. Scientific considerations for future spectroscopic measurements from space of activity on the Sun

    Science.gov (United States)

    Holman, Gordon D.

    2016-12-01

    High-resolution UV and X-ray spectroscopy are important to understanding the origin and evolution of magnetic energy release in the solar atmosphere, as well as the subsequent evolution of heated plasma and accelerated particles. Electromagnetic radiation is observed from plasma heated to temperatures ranging from about 10 kK to above 10 MK, from accelerated electrons emitting photons primarily at X-ray energies, and from ions emitting in γ rays. These observations require space-based instruments sensitive to emissions at wavelengths shorter than the near UV. This article reviews some recent observations with emphasis on solar eruptive events, the models that describe them, and the measurements they indicate are needed for substantial progress in the future. Specific examples are discussed demonstrating that imaging spectroscopy with a cadence of seconds or better is needed to follow, understand, and predict the evolution of solar activity. Critical to substantial progress is the combination of a judicious choice of UV, EUV, and soft X-ray imaging spectroscopy sensitive to the evolution of this thermal plasma combined with hard X-ray imaging spectroscopy sensitive to suprathermal electrons. The major challenge will be to conceive instruments that, within the bounds of possible technologies and funding, have the flexibility and field of view to obtain spectroscopic observations where and when events occur while providing an optimum balance of dynamic range, spectral resolution and range, and spatial resolution.

  11. Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

    Science.gov (United States)

    Mamouri, R. E.; Papayannis, A.; Amiridis, V.; Müller, D.; Kokkalis, P.; Rapsomanikis, S.; Karageorgos, E. T.; Tsaknakis, G.; Nenes, A.; Kazadzis, S.; Remoundaki, E.

    2012-07-01

    A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project, which took place between 15-31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers that occurred on 20-21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single-scattering albedo ω) and mean complex refractive index (m)) at selected heights in the 2-3 km height region. We found that reff was 0.14-0.4 (±0.14) μm, ω was 0.63-0.88 (±0.08) (at 532 nm) and m ranged from 1.44 (±0.10) + 0.01 (±0.01)i to 1.55 (±0.12) + 0.06 (±0.02)i, in good agreement (only for the reff values) with in situ aircraft measurements. The water vapor and temperature profiles were incorporated into the ISORROPIA II model to propose a possible in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2-3 km height region gave a variable range of sulfate (0-60%) and organic carbon (OC) content (0-50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data.

  12. The Orbiting Carbon Observatory (OCO-2): spectrometer performance evaluation using pre-launch direct sun measurements

    Science.gov (United States)

    Frankenberg, C.; Pollock, R.; Lee, R. A. M.; Rosenberg, R.; Blavier, J.-F.; Crisp, D.; O'Dell, C. W.; Osterman, G. B.; Roehl, C.; Wennberg, P. O.; Wunch, D.

    2015-01-01

    The Orbiting Carbon Observatory-2 (OCO-2), launched on 2 July 2014, is a NASA mission designed to measure the column-averaged CO2 dry air mole fraction, XCO2. Towards that goal, it will collect spectra of reflected sunlight in narrow spectral ranges centered at 0.76, 1.6 and 2.0 μm with a resolving power (λ/Δ λ) of 20 000. These spectra will be used in an optimal estimation framework to retrieve XCO2. About 100 000 cloud free soundings of XCO2 each day will allow estimates of net CO2 fluxes on regional to continental scales to be determined. Here, we evaluate the OCO-2 spectrometer performance using pre-launch data acquired during instrument thermal vacuum tests in April 2012. A heliostat and a diffuser plate were used to feed direct sunlight into the OCO-2 instrument and spectra were recorded. These spectra were compared to those collected concurrently from a nearby high-resolution Fourier Transform Spectrometer that was part of the Total Carbon Column Observing Network (TCCON). Using the launch-ready OCO-2 calibration and spectroscopic parameters, we performed total column scaling fits to all spectral bands and compared these to TCCON results. On 20 April, we detected a CO2 plume from the Los Angeles basin at the JPL site with strongly enhanced short-term variability on the order of 1% (3-4 ppm). We also found good (< 0.5 ppm) inter-footprint consistency in retrieved XCO2. The variations in spectral fitting residuals are consistent with signal-to-noise estimates from instrument calibration, while average residuals are systematic and mostly attributable to remaining errors in our knowledge of the CO2 and O2 spectroscopic parameters. A few remaining inconsistencies observed during the tests may be attributable to the specific instrument setup on the ground and will be re-evaluated with in-orbit data.

  13. Dual-channel filter photometer system for biocomponent content determination in diesel oil

    Science.gov (United States)

    Gołębiowski, Jacek; Prohuń, Tomasz

    2008-07-01

    Currently, infrared spectrometry is the most often used method of determination of the biocomponent content in diesel oil, but this is also an expensive and time-consuming process. In this study, a portable, low-cost dual-channel filter photometer system is presented which meets the requirements of the European standard for biocomponent concentration measurements in diesel fuel. The results obtained using this novel system are reported and compared to the measurements made using a standard infrared spectrometer for biodiesel concentration between 0% and 20% by weight. The advantages of the new system, such as its adaptability to the different environmental conditions of analysis, are also discussed.

  14. Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector

    CERN Document Server

    Smirnov, O Y; Appel, S; Bellini, G; Benziger, J; Bick, D; Bonfini, G; Bravo, D; Caccianiga, B; Calaprice, F; Caminata, A; Cavalcante, P; Chepurnov, A; Choi, K; D'Angelo, D; Davini, S; Derbin, A; Di Noto, L; Drachnev, I; Empl, A; Etenko, A; Fomenko, K; Franco, D; Gabriele, F; Galbiati, C; Ghiano, C; Giammarchi, M; Goeger-Neff, M; Goretti, A; Gromov, M; Hagner, C; Hungerford, E; Ianni, Aldo; Ianni, Andrea; Jedrzejczak, K; Kaiser, M; Kobychev, V; Korablev, D; Korga, G; Kryn, D; Laubenstein, M; Lehnert, B; Litvinovich, E; Lombardi, F; Lombardi, P; Ludhova, L; Lukyanchenko, G; Machulin, I; Manecki, S; Maneschg, W; Marcocci, S; Meroni, E; Meyer, M; Miramonti, L; Misiaszek, M; Mosteiro, P; Muratova, V; Neumair, B; Oberauer, L; Obolensky, M; Ortica, F; Otis, K; Pagani, L; Pallavicini, M; Papp, L; Perasso, L; Pocar, A; Ranucci, G; Razeto, A; Re, A; Romani, A; Roncin, R; Rossi, N; Schönert, S; Semenov, D; Simgen, H; Skorokhvatov, M; Sotnikov, A; Sukhotin, S; Suvorov, Y; Tartaglia, R; Testera, G; Thurn, J; Toropova, M; Unzhakov, E; Vogelaar, R B; von Feilitzsch, F; Wang, H; Weinz, S; Winter, J; Wojcik, M; Wurm, M; Yokley, Z; Zaimidoroga, O; Zavatarelli, S; Zuber, K; Zuzel, G

    2015-01-01

    Neutrino produced in a chain of nuclear reactions in the Sun starting from the fusion of two protons, for the first time has been detected in a real-time detector in spectrometric mode. The unique properties of the Borexino detector provided an oppurtunity to disentangle pp-neutrino spectrum from the background components. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 10$^{5}$ years time scale, and sets a strong limit on the power production in the unknown energy sources in the Sun of no more than 4\\% of the total energy production at 90\\% C.L.

  15. Measurement of neutrino flux from the primary proton-proton fusion process in the Sun with Borexino detector

    Science.gov (United States)

    Smirnov, O. Yu.; Agostini, M.; Appel, S.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cavalcante, P.; Chepurnov, A.; Choi, K.; D'Angelo, D.; Davini, S.; Derbin, A.; Di Noto, L.; Drachnev, I.; Empl, A.; Etenko, A.; Fomenko, K.; Franco, D.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Gromov, M.; Hagner, C.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jedrzejczak, K.; Kaiser, M.; Kobychev, V.; Korablev, D.; Korga, G.; Kryn, D.; Laubenstein, M.; Lehnert, B.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Machulin, I.; Manecki, S.; Maneschg, W.; Marcocci, S.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Mosteiro, P.; Muratova, V.; Neumair, B.; Oberauer, L.; Obolensky, M.; Ortica, F.; Otis, K.; Pagani, L.; Pallavicini, M.; Papp, L.; Perasso, L.; Pocar, A.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Semenov, D.; Simgen, H.; Skorokhvatov, M.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Unzhakov, E.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Winter, J.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.

    2016-11-01

    Neutrino produced in a chain of nuclear reactions in the Sun starting from the fusion of two protons, for the first time has been detected in a real-time detector in spectrometric mode. The unique properties of the Borexino detector provided an oppurtunity to disentangle pp-neutrino spectrum from the background components. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 105 years time scale, and sets a strong limit on the power production in the unknown energy sources in the Sun of no more than 4% of the total energy production at 90% C.L.

  16. Electro-Optics of an Experimental Quantum-Optical Photometer

    Science.gov (United States)

    Solomos, N. H.

    2010-07-01

    The first working version of a new ultrafast three-beam photon counting photometer (QOP) has been materialized and demonstrated by the Applied Physics / Electro-optics Laboratory of the Hellenic Naval Academy in Piraeus. The QOP has been installed on the new 0.51m TVD telescope. The instrument is currently being used for quantum-optical study of atmospheric transmission in green monochromatic light over slant paths, at the RFK/Eudoxos Observatories. Actively quenched Single Photon Avalanche Diode detectors can be interchangeably deployed in addition to PMTs and LLL-CCDs. It is also intended for the testing of various approaches for solving the difficult problem of coupling light efficiently to the very small sensitive areas of SPADS, either using fiber couplers, or novel technologies like dedicated fiber tapers. Some particulars of the instrument design philosophy and its optomechanical construction are very briefly mentioned further below. However, it is appropriate to comment, firstly, on its purpose/rationale: The successful formalism of Glauber that led to the quantum-optical framework pertinent to the study of light in the terrestrial laboratories could, perhaps, be proven equally fruitful if applied to celestial light as well. Adopting the new idea of describing an arbitrary light state in terms of coherence functions, it is easily concluded that conventional astronomical instrumentation measures only spatial (imaging) or temporal (spectroscopy) coherence properties of the incoming photon stream. However, higher order spatiotemporal coherence (manifested as correlations among separated photon detection events) convey blueprints of the emission mechanism itself or even of the photon scattering history written in the course of the long path from the emitter to the telescope. To extract this information, high photon fluxes and unprecedented timing resolutions are needed. Our gradual entrance to the era of Extremely Large Telescopes combined with certain new

  17. Design of absorbency photometer used in a fully automatic ELISA analyzer

    Science.gov (United States)

    Dong, Ningning; Zhu, Lianqing; Dong, Mingli; Niu, Shouwei

    2008-03-01

    Absorbency measurement is the most important step in the ELISA analysis. Based on the spectrophotometry, absorbency photometer system used in a fully automatic ELISA analyzer is developed. The system is one core module of the fully automatic ELISA analyzer. The principle and function of the system is analyzed. Three main units of the system, the photoelectric transform unit, the data processing unit and the communication and control unit, are designed and debugged. Finally, the test of the system is carried out using the verification plate. The experiment results agree well with the requirements.

  18. SCIENCE OF SUN PHOTOMETRY

    Directory of Open Access Journals (Sweden)

    Alexandru Dan Toma

    2013-07-01

    Full Text Available Typically, the total amount of gases and particles in a column of atmosphere cannot be determined from measurements just at Earth's surface, by a single measurement essentially at the bottom of the atmosphere column. Balloons, airplanes, and rockets are all used to perform direct measurements in the atmosphere at altitudes up to and beyond the stratosphere. Satellite-based instruments provide global views, but it is difficult to infer surface and column distributions from space-based measurements, so such measurements must still be supplemented by ground-based measurements. Sun photometry is an important way of probing the atmosphere from the ground to measure the effects of the atmosphere on Sun radiation crossing through the atmosphere to Earth's surface. These indirect technique provide information about the entire atmosphere above the observer, not just the atmosphere that can be sampled directly close to Earth's surface.

  19. Spaceborne Sun-Induced Vegetation Fluorescence Time Series from 2007 to 2015 Evaluated with Australian Flux Tower Measurements

    Directory of Open Access Journals (Sweden)

    Abram F. J. Sanders

    2016-10-01

    Full Text Available A global, monthly averaged time series of Sun-induced Fluorescence (SiF, spanning January 2007 to June 2015, was derived from Metop-A Global Ozone Monitoring Experiment 2 (GOME-2 spectral measurements. Far-red SiF was retrieved using the filling-in of deep solar Fraunhofer lines and atmospheric absorption bands based on the general methodology described by Joiner et al, AMT, 2013. A Principal Component (PC analysis of spectra over non-vegetated areas was performed to describe the effects of atmospheric absorption. Our implementation (SiF KNMI is an independent algorithm and differs from the latest implementation of Joiner et al, AMT, 2013 (SiF NASA, v26, because we used desert reference areas for determining PCs (as opposed to cloudy ocean and some desert and a wider fit window that covers water vapour and oxygen absorption bands (as opposed to only Fraunhofer lines. As a consequence, more PCs were needed (35 as opposed to 12. The two time series (SiF KNMI and SiF NASA, v26 correlate well (overall R of 0.78 except for tropical rain forests. Sensitivity experiments suggest the strong impact of the water vapour absorption band on retrieved SiF values. Furthermore, we evaluated the SiF time series with Gross Primary Productivity (GPP derived from twelve flux towers in Australia. Correlations for individual towers range from 0.37 to 0.84. They are particularly high for managed biome types. In the de-seasonalized Australian SiF time series, the break of the Millennium Drought during local summer of 2010/2011 is clearly observed.

  20. The Hetu'u Global Network: Measuring the Distance to the Sun Using the June 5th/6th Transit of Venus

    CERN Document Server

    Faherty, Jacqueline K; Miller, Scott T

    2012-01-01

    In the spirit of historic astronomical endeavors, we invited school groups across the globe to collaborate in a solar distance measurement using the rare June 5/6th transit of Venus. In total, we recruited 19 school groups spread over 6 continents and 10 countries to participate in our Hetu'u Global Network. Applying the methods of French astronomer Joseph-Nicolas Delisle, we used individual second and third Venus-Sun contact times to calculate the distance to the Sun. Ten of the sites in our network had amiable weather; 8 of which measured second contact and 5 of which measured third contact leading to consistent solar distance measurements of 152+/-30 million km and 163+/-30 million km respectively. The distance to the Sun at the time of the transit was 152.25 million km; therefore, our measurements are also consistent within 1sigma of the known value. The goal of our international school group network was to inspire the next generation of scientists using the excitement and accessibility of a rare astronom...

  1. Single Particle Soot Photometer intercomparison at the AIDA chamber

    Directory of Open Access Journals (Sweden)

    M. Laborde

    2012-12-01

    Full Text Available Soot particles, consisting of black carbon (BC, organic carbon (OC, inorganic salts, and trace elements, are emitted into the atmosphere during incomplete combustion. Accurate measurements of atmospheric BC are important as BC particles cause adverse health effects and impact the climate.

    Unfortunately, the accurate measurement of the properties and mass concentrations of BC particles remains difficult. The Single Particle Soot Photometer (SP2 can contribute to improving this situation by measuring the mass of refractory BC in individual particles as well as its mixing state.

    Here, the results of the first detailed SP2 intercomparison, involving 6 SP2s from 6 different research groups, are presented, including the most evolved data products that can presently be calculated from SP2 measurements.

    It was shown that a detection efficiency of almost 100% down to 1 fg BC per particle can readily be achieved, and that this limit can be pushed down to ∼0.2 fg BC with optimal SP2 setup. Number and mass size distributions of BC cores agreed within ±5% and ±10%, respectively, in between the SP2s, with larger deviations in the range below 1 fg BC.

    The accuracy of the SP2's mass concentration measurement depends on the calibration material chosen. The SP2 has previously been shown to be equally sensitive to fullerene soot and ambient BC from sources where fossil fuel was dominant and less sensitive to fullerene soot than to Aquadag. Fullerene soot was therefore chosen as the standard calibration material by the SP2 user community; however, many data sets rely solely on Aquadag calibration measurements. The difference in SP2 sensitivity was found to be almost equal (fullerene soot to Aquadag response ratio of ∼0.75 at 8.9 fg BC for all SP2s. This allows the calculation of a fullerene soot equivalent calibration curve from a measured Aquadag calibration, when no fullerene soot calibration is available. It could be

  2. Single Particle Soot Photometer intercomparison at the AIDA chamber

    Directory of Open Access Journals (Sweden)

    M. Laborde

    2012-05-01

    Full Text Available Soot particles, consisting of black carbon (BC, organic carbon (OC, inorganic salts, and trace elements, are emitted into the atmosphere during incomplete combustion. Accurate measurements of atmospheric BC are important as BC particles cause adverse health effects and impact the climate.

    Unfortunately, the accurate measurement of the properties and mass concentrations of BC particles remains difficult. The Single Particle Soot Photometer (SP2 can contribute to improving this situation by measuring the mass of refractory BC in individual particles as well as its mixing state.

    Here, the results of the first detailed SP2 intercomparison, involving 6 SP2s from 6 different research groups, are presented, including the most evolved data products that can presently be calculated from SP2 measurements.

    It was shown that a detection efficiency of almost 100% down to 1 fg BC per particle can readily be achieved, and that this limit can be pushed down to ~0.3 fg BC with optimal SP2 setup. Number and mass size distributions of BC cores agreed within ±5% and ±10%, respectively, in between the SP2s, with larger deviations in the range below 1 fg BC.

    The accuracy of the SP2's mass concentration measurement depends on the calibration material chosen. The SP2 has previously been shown to be equally sensitive to fullerene soot and ambient BC from sources where fossil fuel were dominant and less sensitive to fullerene soot than to Aquadag. Fullerene soot was therefore chosen as the standard calibration material by the SP2 user community, however many datasets rely solely on Aquadag calibration measurements. The difference in SP2 sensitivity was found to be almost equal (fullerene soot to Aquadag response ratio of ~0.75 at 8.9 fg BC for all SP2s. This allows the calculation of a fullerene soot equivalent calibration curve from a measured Aquadag calibration, when no fullerene soot calibration is available. It could be shown

  3. The MEDUSA electron and ion spectrometer and the PIA ultraviolet photometers on Astrid-2

    Directory of Open Access Journals (Sweden)

    O. Norberg

    Full Text Available The miniature electron and ion spectrometer MEDUSA on Astrid-2 consists of two "top-hat"-type spherical electrostatic analyzers, sharing a common top-hat. Fast energy sweeps (16 electron sweeps and 8 ion sweeps per second allow for very high temporal resolution measurements of a two-dimensional slice of the particle distribution function. The energy range covered, is in the case of electrons, 4 eV to 22 keV and, in the case of ions, 2 eV to 12 keV. MEDUSA is mounted with its aperture close to the spin plane of Astrid-2, which allows for good pitch-angle coverage when the local magnetic field is in the satellite spin plane. The PIA-1/2 spin-scanning ultraviolet photometers measure auroral emissions. Using the spacecraft spin and orbital motion, it is possible to create two-dimensional images from the data. Spin-scanning photometers, such as PIA, are low-cost, low mass alternatives to auroral imagers, but place constraints on the satellite attitude. Data from MEDUSA are used to study processes in the auroral region, in particular, electrodynamics of aurora and "black aurora". MEDUSA is also a technological development, paving the way for highly capable, miniaturized particle spectrometers.

    Key words. Ionosphere (instruments and techniques – Magnetospheric physics (auroral phenomena; instruments and techniques

  4. The Diabolo photometer and the future of ground-based millimetric bolometer devices

    CERN Document Server

    Désert, F X; Camus, P; Giard, M; Pointecouteau, E; Aghanim, N; Bernard, J P; Coron, N; Lamarre, J M; Marty, P; Delabrouille, J; Soglasnova, V; Camus, Ph.; Marty, Ph.

    2001-01-01

    The millimetric atmospheric windows at 1 and 2 mm are interesting targets for cosmological studies. Two broad areas appear leading this field: 1) the search for high redshift star-forming galaxies and 2) the measurement of Sunyaev-Zel'dovich (SZ) effect in clusters of galaxies at all redshifts. The Diabolo photometer is a dual-channel photometer working at 1.2 and 2.1 mm and dedicated to high angular resolution measurements of the Sunyaev--Zel'dovich effect towards distant clusters. It uses 2 by 3 bolometers cooled down to 0.1 K with a compact open dilution cryostat. The high resolution is provided by the IRAM 30 m telescope. The result of several Winter campaigns are reported here, including the first millimetric map of the SZ effect that was obtained by Pointecouteau et al. (2001) on RXJ1347-1145, the non-detection of a millimetric counterpart to the radio decrement towards PC1643+4631 and 2 mm number count upper limits. We discuss limitations in ground-based single-dish millimetre observations, namely sky ...

  5. Experimental measurements of a prototype high-concentration Fresnel lens and sun-tracking method for photovoltaic panel's efficiency enhancement

    Science.gov (United States)

    Rajaee, Meraj; Ghorashi, Seyed Mohamad Bagher

    2015-08-01

    Concentrator photovoltaic modules are a promising technology for highly efficient solar energy conversion. This system presents several advantages due to additional degrees of freedom that has been provided by the spectral separation such as cost and mass reduction, increase in the incident solar flux on PV cells and performances. This paper has proposed a unique photovoltaic solar cell system that consists of semi-Fresnel lens convergent structure and a novel two axis sun tracking module to enhance the efficiency of solar cell by using less cell area and energy losses. The grooves of this lens are calculated according to the refraction and convergent angles of the light easy for perpendicular incidence angle. The update time interval during tracking causes misalignment of the lens' optical axis versus the sunrays. Then an inventive sun-tracking method is introduced to adjust the module so that the incident rays are always perpendicular to the module's surface. As a result, all rays will be refracted with the predetermined angles. This way the focus area is reduced and smaller cells can be used. We also mentioned different module connections in order to provide compensation method during losses, for networks and power systems. Experimental results show that using semi-Fresnel lens, along with the sun-tracking method increases the efficiency of PV panel.

  6. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  7. Calibration and First light of the Diabolo photometer at the Millimetre and Infrared Testa Grigia Observatory

    CERN Document Server

    Benoît, A; Coron, N; De Petris, M; Désert, F X; Giard, M; Bernard, J P; Crussaire, J P; Dambier, G; De Bernardis, P; Delabrouille, J; De Luca, A; De Marcillac, P; Jegoudez, G; Lamarre, J M; Leblanc, J W; Lepeltier, J P; Leriche, B; Mainella, G; Narbonne, J; Pajot, F; Pons, R; Puget, J L; Pujol, S; Recouvreur, G; Serra, G; Soglasnova, V; Torre, J P; Vozzi, B

    1999-01-01

    We have designed and built a large-throughput dual channel photometer, Diabolo. This photometer is dedicated to the observation of millimetre continuum diffuse sources, and in particular, of the Sunyaev-Zel'dovich effect and of anisotropies of the 3K background. We describe the optical layout and filtering system of the instrument, which uses two bolometric detectors for simultaneous observations in two frequency channels at 1.2 and 2.1 mm. The bolometers are cooled to a working temperature of 0.1 K provided by a compact dilution cryostat. The photometric and angular responses of the instrument are measured in the laboratory. First astronomical light was detected in March 1995 at the focus of the new Millimetre and Infrared Testa Grigia Observatory (MITO) Telescope. The established sensitivity of the system is of 7 mK_RJ s^1/2$. For a typical map of at least 10 beams, with one hour of integration per beam, one can achieve the rms values of y_SZ ~ 7 10^-5 and the 3K background anisotropy Delta T/T ~ 7 10^-5, i...

  8. The Sun's X-ray Emission During the Recent Solar Minimum

    Science.gov (United States)

    Sylwester, Janusz; Kowalinski, Mirek; Gburek, Szymon; Siarkowski, Marek; Kuzin, Sergey; Farnik, Frantisek; Reale, Fabio; Phillips, Kenneth J. H.

    2010-02-01

    The Sun recently underwent a period of a remarkable lack of major activity such as large flares and sunspots, without equal since the advent of the space age a half century ago. A widely used measure of solar activity is the amount of solar soft X-ray emission, but until recently this has been below the threshold of the X-ray-monitoring Geostationary Operational Environmental Satellites (GOES). There is thus an urgent need for more sensitive instrumentation to record solar X-ray emission in this range. Anticipating this need, a highly sensitive spectrophotometer called Solar Photometer in X-rays (SphinX) was included in the solar telescope/spectrometer TESIS instrument package on the third spacecraft in Russia's Complex Orbital Observations Near-Earth of Activity of the Sun (CORONAS-PHOTON) program, launched 30 January 2009 into a near-polar orbit. SphinX measures X-rays in a band similar to the GOES longer-wavelength channel.

  9. Design of a sun tracker for the automatic measurement of spectral irradiance and construction of an irradiance database in the 330-1100 nm range

    Energy Technology Data Exchange (ETDEWEB)

    Canada, J.; Maj, A. [Departamento de Termodinamica Aplicada, Universidad Politecnica de Valencia, Camino de Vera, s/n. 46022 Valencia (Spain); Utrillas, M.P.; Martinez-Lozano, J.A.; Pedros, R.; Gomez-Amo, J.L. [Departamento de Fisica de la Tierra y Termodinamica, Facultat de Fisica, Universitat de Valencia, 46100 Burjassot (Valencia) (Spain)

    2007-10-15

    An automatic global and direct solar spectral irradiance system has been designed based on two LICOR spectro radiometers equipped with fibre optics and remote cosine sensors. To measure direct irradiance a sun tracker based on step motors has been developed. The whole system is autonomous and works continuously. From the measurements provided by this system a spectral irradiance database in the 330-1100 nm range has been created. This database contains normal direct and global horizontal irradiances as well as diffuse irradiance on a horizontal plane, together with total atmospheric optical thickness and aerosol optical depth. (author)

  10. Use of acoustic wave travel-time measurements to probe the near-surface layers of the Sun

    Science.gov (United States)

    Jefferies, S. M.; Osaki, Y.; Shibahashi, H.; Duvall, T. L., Jr.; Harvey, J. W.; Pomerantz, M. A.

    1994-01-01

    The variation of solar p-mode travel times with cyclic frequency nu is shown to provide information on both the radial variation of the acoustic potential and the depth of the effective source of the oscillations. Observed travel-time data for waves with frequency lower than the acoustic cutoff frequency for the solar atmosphere (approximately equals 5.5 mHz) are inverted to yield the local acoustic cutoff frequency nu(sub c) as a function of depth in the outer convection zone and lower atmosphere of the Sun. The data for waves with nu greater than 5.5 mHz are used to show that the source of the p-mode oscillations lies approximately 100 km beneath the base of the photosphere. This depth is deeper than that determined using a standard mixing-length calculation.

  11. SphinX: A Fast Solar Photometer in X-rays

    Indian Academy of Sciences (India)

    J. Sylwester; S. Kuzin; Yu. D. Kotov; F. Farnik; F. Reale

    2008-03-01

    The scientific goals and construction details of a new design, Polish X-ray spectrophotometer are given. It will be incorporated within the Russian TESIS X and EUV complex aboard the forthcoming CORONAS solar mission. SphinX (Solar Photometer in X-rays) will use PIN silicon detectors for high time resolution (0.01 s) measurements of the solar spectra of quiet and active corona in the range 0.5–15 keV. A new filter-fluorescence target concept will be employed to allow for a fast photometry of the solar X-ray flux variations in selected, well defined narrow spectral bands including the Fe xxvi and Fe xxv iron line groups.

  12. Spatio-temporal variations of plant mediated exchange - diurnal and seasonal changes of the function status of plant canopies measured by sun-induced fluorescence

    Science.gov (United States)

    Rascher, Uwe; Schickling, Anke; Crewell, Susanne; Schween, Jan; Geiß, Heiner

    2010-05-01

    Fluxes of plant mediated exchange processes are large and substantially influence patterns in atmospheric CO2 concentrations and water vapor. Plant canopies are not constant, but continuously adapt their physiology to the ever changing environmental conditions. Structural changes of plant canopies mainly occur on the time scale of weeks and seasons and are generally parametrized in regional and global carbon and water models. Changes of the physiological status of plant ecosystems, however, may occur within hours or a few days and are often not accounted for in models. Nevertheless, a reduction of photosynthesis because of e.g. stress may greatly reduce carbon and water exchange below the theoretical optimum. Such physiological changes are often are not correctly parametrized in spatially explicit and high resolution carbon and water models. For a better understanding of the diurnal and seasonal variations of soil-vegetation-atmosphere exchange processes, the structure and function of two main agricultural crops were monitored over two years in the frame of the collaborative research consortium Transregio TR32. Seasonal development of the two main crops of the region, winter wheat and sugar beet, has been characterized during diurnal courses using non invasive methods ranging from leaf to canopy level including gas exchange, PAM fluorometry and eddy correlation measurements. The day course of photosynthetic capacity varied between the two species by being constant during the day for winter wheat whereas sugar beet showed a constant decrease over the day. The highest photosynthetic electron transport rates appeared before solar noon. Additionally the region was scanned by an airborne high-resolution spectrometer that allowed the extraction of sun-induced fluorescence. Sun-induced fluorescence is currently evaluated to serve as a direct measure of photosynthetic efficiency from air- and spaceborne platforms. In this presentation we present the first conceptual view

  13. Sun and Sun Worship in Different Cultures

    Science.gov (United States)

    Farmanyan, S. V.; Mickaelian, A. M.

    2014-10-01

    The Sun symbol is found in many cultures throughout history, it has played an important role in shaping our life on Earth since the dawn of time. Since the beginning of human existence, civilisations have established religious beliefs that involved the Sun's significance to some extent. As new civilisations and religions developed, many spiritual beliefs were based on those from the past so that there has been an evolution of the Sun's significance throughout cultural development. For comparing and finding the origin of the Sun we made a table of 66 languages and compared the roots of the words. For finding out from where these roots came from, we also made a table of 21 Sun Gods and Goddesses and proved the direct crossing of language and mythology.

  14. Sun's rap song

    Science.gov (United States)

    Hogan, M.; Lee, W.

    1995-07-01

    We present a rap song composed for the Sun, our star. This Sun's Rap Song can be utilized in classroom teaching to spark the students' interest and facilitate the students' learning of the relevant subjects.

  15. MedSun Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medical Product Safety Network (MedSun) is an adverse event reporting program launched in 2002. The primary goal for MedSun is to work collaboratively with the...

  16. MedSun Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medical Product Safety Network (MedSun) is an adverse event reporting program launched in 2002. The primary goal for MedSun is to work collaboratively with the...

  17. How Bright Is the Sun?

    Science.gov (United States)

    Berr, Stephen

    1991-01-01

    Presents a sequence of activities designed to allow eighth grade students to deal with one of the fundamental relationships that govern energy distribution. Activities guide students to measure light bulb brightness, discover the inverse square law, compare light bulb light to candle light, and measure sun brightness. (two references) (MCO)

  18. Seasons by the Sun

    Science.gov (United States)

    Stark, Meri-Lyn

    2005-01-01

    Understanding the Sun has challenged people since ancient times. Mythology from the Greek, Inuit, and Inca cultures attempted to explain the daily appearance and nightly disappearance of the Sun by relating it to a chariot being chased across the sky. While people no longer believe the Sun is a chariot racing across the sky, teachers are still…

  19. Personal, Seasonal Suns

    Science.gov (United States)

    Sutley, Jane

    2010-01-01

    This article presents an art project designed for upper-elementary students to (1) imagine visual differences in the sun's appearance during the four seasons; (2) develop ideas for visually translating their personal experiences regarding the seasons to their sun drawings; (3) create four distinctive seasonal suns using colors and imagery to…

  20. The measurement of constitutive and facultative skin pigmentation and estimation of sun exposure in Caucasians with basal cell carcinoma and cutaneous malignant melanoma

    DEFF Research Database (Denmark)

    Lock-Andersen, J; Drzewiecki, K T; Wulf, H C

    1998-01-01

    In two identical and simultaneously performed case-control studies of basal cell carcinoma (BCC) and cutaneous malignant melanoma (CMM) with age-matched, sex-matched and residence-matched controls, skin pigmentation was measured objectively by skin reflectance spectroscopy in 145 BCC patients...... by all subjects. There were no statistically significant differences in constitutive skin pigmentation at the buttocks between BCC patients and controls (P = 0.96) or between CMM patients and controls (P = 0.13). Facultative skin pigmentation in ultraviolet-exposed sites was not significantly different...... between BCC patients and controls except that women patients had higher pigmentation at the lateral side of the upper arm. For CMM, men patients had higher pigmentation at the lateral side of the upper arm. Self-estimations of sun exposure did not show differences between patients and controls...

  1. Advanced GLS map-making for the Herschel's photometers

    Science.gov (United States)

    Piazzo, Lorenzo; Raguso, Maria C.; Mastrogiuseppe, Marco; Calzoletti, Luca; Altieri, Bruno

    2016-07-01

    We discuss Generalised Least Squares (GLS) map-making for the data of the Herschel satellite's photometers, which is a difficult task, due to the many disturbances affecting the data, and requires appropriate pre- and post-processing. Taking an existing map-maker as a reference, we propose several advanced techniques, which can improve both the quality of the estimate and the efficiency of the software. As a main contribution we discuss two disturbances, which have not been studied yet and may be detrimental to the image quality. The first is a data shift, due to delays in the timing system or in the processing chain. The second is a random noise, termed pixel noise, due to the jitter and the approximation of the pointing information. For both these disturbances, we develop a mathematical model and propose a compensation method. As an additional contribution, we note that the performance can be improved by properly adapting the algorithm parameters to the data being processed and discuss an automatic setting method. We also provide a rich set of examples and experiments, illustrating the impact of the proposed techniques on the image quality and the execution speed.

  2. Ground-based measurements of aerosol optical properties and radiative forcing in North China

    Institute of Scientific and Technical Information of China (English)

    Hongbin Chen; Xiangao Xia; Pucai Wang; Wenxing Zhang

    2007-01-01

    In order to gain an insight into the aerosol properties and their climatic effect over the continental source regions of China, it is of significance to carry out long-term ground-based measurements of aerosol optical properties and radiative forcing. A couple of temporary and permanent Aerosol Robotic Network (AERONET) sites and three comprehensive radiative sites were established in China as a result of international cooperation in recent years. Heavy aerosol loading and significant temporal and spatial variation over North China are revealed by the AERONET data.Aerosol-induced reductions in surface radiation budget are examined on the basis of collocated observations by sun photometers and pyranometers.

  3. A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2015-05-01

    Full Text Available Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS- instruments or Multi-AXis (MAX- DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

  4. Diode laser photometer for process gas analysis in the near infrared; Diodenlaserphotometer im Nahen Infrarot fuer die Prozessanalyse

    Energy Technology Data Exchange (ETDEWEB)

    Cerff, K.

    1991-09-01

    A process photometer for the near infrared is designed taking into account the spectral properties of eligible heteropolar molecular compounds as well as the properties exhibited by commercially available diode lasers for communication engineering at 1.3 and 1.5 {mu}m, respectively. Compared with the conventional systems, this new process photometer has a high selectivity. Two frequency tuning methods are investigated. On the basis of the values measured, the method suitable for the InGaAs(P) diode lasers is determined. This method is then compared with that used for cooled lead salt diode lasers. A special method for the calculation of the hydrogen fluoride concentration with a reduced expenditure is examined for the occurrence of an additional water absorption line. This method is based on the use of the computer already incorporated in the analog device version. Subsequently, the analog device unit tested under operating conditions in the stack of our industrial cooperation partner is described. By means of error assessment, a 1{sigma} standard deviation of 0.066 mg HF/Ncbm is obtained for this version in case of a 100-h measurement. The lower limit of detection of photometer systems with thermal optical sources is 36 mg HF/Ncbm. When using the diode laser photometer presented in this report, this value is reduced to 0.5 mg/Ncbm. (orig./BBR). [Deutsch] Die Konzeption eines gegenueber herkoemmlichen Systemen hochselektiven Prozessphotometers fuer den spektralen Bereich des Nahen Infrarot wird in Abhaengigkeit von den spektralen Eigenschaften der in Frage kommenden heteropolaren Molekuelverbindungen sowie den Eigenschaften der kommerziell verfuegbaren Diodenlaser der Nachrichtentechnik bei 1.3 und 1.5 {mu}m erarbeitet. Zwei Frequenzabstimmverfahren werden untersucht, anhand von Messungen wird das fuer die InGaAs(P)-Diodenlaser geeignete Verfahren ermittelt und gegenueber demjenigen fuer gekuehlte Bleisalz-Diodenlaser abgegrenzt. Ein spezielles Verfahren zur

  5. Status of the SPIRE photometer data processing pipelines during the early phases of the Herschel Mission

    OpenAIRE

    Dowell, C. Darren; Levenson, Louis; Lu, Nanyao; Schulz, Bernhard; Schwartz, Arnold; Shupe, David L.; Xu, C. Kevin; Zhang, Lijun

    2010-01-01

    We describe the current state of the ground segment of Herschel-SPIRE photometer data processing, approximately one year into the mission. The SPIRE photometer operates in two modes: scan mapping and chopped point source photometry. For each mode, the basic analysis pipeline - which follows in reverse the effects from the incidence of light on the telescope to the storage of samples from the detector electronics - is essentially the same as described pre-launch. However, the calibration param...

  6. Earth's Heat Source - The Sun

    CERN Document Server

    Manuel, Oliver K

    2009-01-01

    The Sun encompasses planet Earth, supplies the heat that warms it, and even shakes it. The United Nation Intergovernmental Panel on Climate Change (IPCC) assumed that solar influence on our climate is limited to changes in solar irradiance and adopted the consensus opinion of a Hydrogen-filled Sun, the Standard Solar Model (SSM). They did not consider the alternative solar model and instead adopted another consensus opinion: Anthropogenic greenhouse gases play a dominant role in climate change. The SSM fails to explain the solar wind, solar cycles, and the empirical link of solar surface activity with Earth changing climate. The alternative solar model, that was molded from an embarrassingly large number of unexpected observations revealed by space-age measurements since 1959, explains not only these puzzles but also how closely linked interactions between the Sun and its planets and other celestial bodies induce turbulent cycles of secondary solar characteristics that significantly affect Earth climate.

  7. Test of the MarsSedEx Settling Tube Photometer during the 2nd Swiss Parabolic Flight Campaign

    Science.gov (United States)

    Kuhn, Nikolaus J.; Kuhn, Brigitte; Rüegg, Hans-Rudolf; Zimmermann, Lukas

    2017-04-01

    Gravity affects flow hydraulics and thus limits the application of simple models for sediment transport developed for Earth on Mars. The significance of the differences in sediment settling has been demonstrated for sand-sized particles by measuring settling velocities using video-imaging during parabolic flights. This approach does not work for finer particles because they cannot be distinguished individually on a video. Tracking of fine sediment clouds is also difficult using videos because changes in density are not captured. Photometers, on the other hand, are able to capture differences in turbidity and offer the potential to measure the settling behaviour of clouds of fine and differently-sized sediment particles. In this study, the feasibility of using a settling-tube photometer used for the rapid assessment of settling velocities developed by the University of Basel during a parabolic flight with reduced gravity is presented. In addition, the potential of the results generated in this Martian-analogue environment to support the identification sediments containing traces of life on Mars is discussed.

  8. Comparison of CME masses and kinetic energies near the Sun and in the inner heliosphere

    Science.gov (United States)

    Webb, D. F.; Howard, R. A.; Jackson, B. V.

    1995-01-01

    Masses have now been determined for many of the CMEs observed in the inner heliosphere by the HELIOS 1 and 2 zodiacal light photometers. The speed of the brightest material of each CME has also been measured so that, for events having both mass and speed determinations, the kinetic energies of the CMEs are estimated. We compare the masses and kinetic energies of the individual CMEs measured in the inner heliosphere by HELIOS and near the Sun from observations by the SOLWIND (1979-1983) and SMM coronagraphs (1980). Where feasible we also compare the speeds of the same CMEs. We find that the HELIOS masses and energies tend to be somewhat larger by factors of 2-5 than those derived from the coronagraph data. We also compare the distribution of the masses and energies of the HELIOS and coronagraph CMEs over the solar cycle. These results provide an important baseline for observations of CMEs from coronagraphs, from the ISEE-3/ICE, WIND and Ulysses spacecraft and in the future from SOHO.

  9. A compact, fast ozone UV photometer and sampling inlet for research aircraft

    Directory of Open Access Journals (Sweden)

    R. S. Gao

    2012-05-01

    Full Text Available In situ measurements of atmospheric ozone (O3 are performed routinely from many research aircraft platforms. The most common technique depends on the strong absorption of ultraviolet (UV light by ozone. As atmospheric science advances to the widespread use of unmanned aircraft systems (UASs, there is an increasing requirement for minimizing instrument space, weight, and power while maintaining instrument accuracy, precision and time response. The design and use of a new, dual-beam, polarized, UV photometer instrument for in situ O3 measurements is described. The instrument has a fast sampling rate (2 Hz, high accuracy (3%, and precision (1.1 × 1010 O3 molecules cm−3. The size (36 l, weight (18 kg, and power (50–200 W make the instrument suitable for many UAS and other airborne platforms. Inlet and exhaust configurations are also described for ambient sampling in the troposphere and lower stratosphere (1000–50 mb that optimize the sample flow rate to increase time response while minimizing loss of precision due to induced turbulence in the sample cell. In-flight and laboratory intercomparisons with existing O3 instruments show that measurement accuracy is maintained in flight.

  10. Lunar eclipse photometry: absolute luminance measurements and modeling.

    Science.gov (United States)

    Hernitschek, Nina; Schmidt, Elmar; Vollmer, Michael

    2008-12-01

    The Moon's time-dependent luminance was determined during the 9 February 1990 and 3 March 2007 total lunar eclipses by using calibrated, industry standard photometers. After the results were corrected to unit air mass and to standard distances for both Moon and Sun, an absolute calibration was accomplished by using the Sun's known luminance and a pre-eclipse lunar albedo of approximately 13.5%. The measured minimum level of brightness in the total phase of both eclipses was relatively high, namely -3.32 m(vis) and -1.7 m(vis), which hints at the absence of pronounced stratospheric aerosol. The light curves were modeled in such a way as to let the Moon move through an artificial Earth shadow composed of a multitude of disk and ring zones, containing a relative luminance data set from an atmospheric radiative transfer calculation.

  11. A Miniaturized Laser Heterodyne Radiometer for Greenhouse Gas Measurements in the Atmospheric Column

    Science.gov (United States)

    Steel, Emily Wilson

    2015-01-01

    Laser Heterodyne Radiometry is a technique adapted from radio receiver technology has been used to measure trace gases in the atmosphere since the 1960s.By leveraging advances in the telecommunications industry, it has been possible to miniaturize this technology.The mini-LHR (Miniaturized Laser Heterodyne Radiometer) has been under development at NASA Goddard Space flight Center since 2009. This sun-viewing instrument measures carbon dioxide and methane in the atmospheric column and operates in tandem with an AERONET sun photometer producing a simultaneous measure of aerosols. The mini-LHR has been extensively field tested in a range of locations ranging in the continental US as well as Alaska and Hawaii and now operates autonomously with sensitivities of approximately 0.2 ppmv and approximately10 ppbv, for carbon dioxide and methane respectively, for 10 averaged scans under clear sky conditions.

  12. Measurement and simulation of transparent building components with sun-shading; Messung und Simulation von transparenten Bauteilen mit Sonnenschutz

    Energy Technology Data Exchange (ETDEWEB)

    Simmler, H.; Manz, H.; Haas, A. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Duebendorf (Switzerland); Favarolo, P.A. [Universita Technica delle Marche, Ancona (Italy)

    2004-12-15

    This paper takes a look at the construction and simulation of modern office buildings that often feature lightweight construction and a high proportion of glazing or even double building skins completely made of glass. In particular, those thermal comfort and cooling aspects are discussed that require that the solar attributes of facade elements are taken into account. Work done at the Swiss Federal materials institute EMPA as part of the International Energy Agency's IEA Task 27 'Performance, durability and sustainability of advanced windows and solar components for building envelopes' is discussed. The properties of glazing and shading systems are presented and discussed. Results obtained by calculation are compared with those obtained from measurements. Modules for the calculation of the properties of glazing elements and their simulation are discussed, as are transparent insulation systems.

  13. Measurement and simulation of transparent building components with sun-shading; Messung und Simulation von transparenten Bauteilen mit Sonnenschutz

    Energy Technology Data Exchange (ETDEWEB)

    Simmler, H.; Manz, H.; Haas, A. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Duebendorf (Switzerland); Favarolo, P.A. [Universita Technica delle Marche, Ancona (Italy)

    2004-12-15

    This paper takes a look at the construction and simulation of modern office buildings that often feature lightweight construction and a high proportion of glazing or even double building skins completely made of glass. In particular, those thermal comfort and cooling aspects are discussed that require that the solar attributes of facade elements are taken into account. Work done at the Swiss Federal materials institute EMPA as part of the International Energy Agency's IEA Task 27 'Performance, durability and sustainability of advanced windows and solar components for building envelopes' is discussed. The properties of glazing and shading systems are presented and discussed. Results obtained by calculation are compared with those obtained from measurements. Modules for the calculation of the properties of glazing elements and their simulation are discussed, as are transparent insulation systems.

  14. The Laboratory Complex for the Calibration of Photometers Using the Optical Method for Determination of the Water Vapor Content in the Earth Atmosphere

    CERN Document Server

    Galkin, V D; Nikanorova, I N; Leiterer, U; Niebert, T; Alekseeva, G A; Novikov, V V; Ilyin, G N; Pakhomov, V P

    2010-01-01

    We describe the laboratory complex for the calibration of photometers that are used in weather service to measure the water vapor content in the Earth atmosphere. The complex was built up in Pulkovo Observatory and developed within the framework of collaboration between Pulkovo Observatory and Lindenberg Meteorological Observatory (Meteorologisches Observatorium Lindenberg - Richard-A{\\ss}mann-Observatorium, Lindenberg, Germany). It is used to obtain calibration dependences for individual devices, and also to develop and compare various methods of construction of calibration dependences. These techniques are based on direct calibration of the photometers, on the use of spectral laboratory transmission functions for water vapor, on calculation methods using spectroscopical databases for individual lines. We hope that when the parameters of the equipment are taken into account in detail and new results for the absorptive power of water vapor are used, the accuracy of determination of the water vapor content in ...

  15. EUV SpectroPhotometer (ESP) in Extreme Ultraviolet Variability Experiment (EVE): Algorithms and Calibrations

    CERN Document Server

    Didkovsky, Leonid; Wieman, Seth; Woods, Tom; Jones, Andrew

    2009-01-01

    The Extreme ultraviolet SpectroPhotometer (ESP) is one of five channels of the Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO). The ESP channel design is based on a highly stable diffraction transmission grating and is an advanced version of the Solar Extreme ultraviolet Monitor (SEM), which has been successfully observing solar irradiance onboard the Solar and Heliospheric Observatory (SOHO) since December 1995. ESP is designed to measure solar Extreme UltraViolet (EUV) irradiance in four first order bands of the diffraction grating centered around 19 nm, 25 nm, 30 nm, and 36 nm, and in a soft X-ray band from 0.1 to 7.0 nm in the zeroth order of the grating. Each band's detector system converts the photo-current into a count rate (frequency). The count rates are integrated over 0.25 sec increments and transmitted to the EVE Science and Operations Center for data processing. An algorithm for converting the measured count rates into solar irradiance and the ES...

  16. Cluster analysis of diurnal variations in BC concentration from Multi-Angle Absorption Photometer

    Science.gov (United States)

    Han, Y.; KIM, C.; Park, J.; Choi, Y.; Ghim, Y.

    2013-12-01

    Black carbon (BC) is emitted from incomplete combustion of carbon-containing fuels, such as fossil fuels (diesel and coal) and biomass burning (forest fires and burning of agricultural waste). We have measured BC concentration using MAAP (Multi-Angle Absorption Photometer, Model 5012, Thermo Scientific) during the past few years. The measurement site is on the rooftop of the five-story building on the hill (37.02 °N, 127.16 °E, 167 m above sea level), about 35 km southeast of Seoul; there are no major emission sources nearby except a 4-lane road running about 1.4 km to the west. Previous studies reveal that the effects of vehicle emissions are not as direct as urban sites but those of biomass burning are general. Diurnal variations of BC concentration are classified using cluster analysis. Typical patterns are determined to identify the primary emissions and their effects on the concentration level. High concentration episodes are discriminated and major factors that influence the evolution of the episodes are investigated.

  17. A conjunct near-surface spectroscopy system for fix-angle and multi-angle continuous measurements of canopy reflectance and sun-induced chlorophyll fluorescence

    Science.gov (United States)

    Zhang, Qian; Fan, Yifeng; Zhang, Yongguang; Chou, Shuren; Ju, Weimin; Chen, Jing M.

    2016-09-01

    An automated spectroscopy system, which is divided into fix-angle and multi-angle subsystems, for collecting simultaneous, continuous and long-term measurements of canopy hyper-spectra in a crop ecosystem is developed. The fix-angle subsystem equips two spectrometers: one is HR2000+ (OceanOptics) covering the spectral range 200-1100 nm with 1.0 nm spectral resolution, and another one is QE65PRO (OceanOptics) providing 0.1 nm spectral resolution within the 730-780 nm spectral range. Both spectrometers connect a cosine-corrected fiber-optic fixed up-looking to collect the down-welling irradiance and a bare fiber-optic to measure the up-welling radiance from the vegetation. An inline fiber-optic shutter FOS-2x2-TTL (OceanOptics) is used to switch between input fibers to collect the signal from either the canopy or sky at one time. QE65PRO is used to permit estimation of vegetation Sun-Induced Fluorescence (SIF) in the O2-A band. The data collection scheme includes optimization of spectrometer integration time to maximize the signal to noise ratio and measurement of instrument dark currency. The multi-angle subsystem, which can help understanding bidirectional reflectance effects, alternatively use HR4000 (OceanOptics) providing 0.1 nm spectral resolution within the 680-800 nm spectral range to measure multi-angle SIF. This subsystem additionally includes a spectrometer Unispec-DC (PPSystems) featuring both up-welling and down-welling channels with 3 nm spectral resolution covering the 300-1100 nm spectral range. Two down-looking fiber-optics are mounted on a rotating device PTU-D46 (FLIR Systems), which can rotate horizontally and vertically at 10° angular step widths. Observations can be used to calculate canopy reflectance, vegetation indices and SIF for monitoring plant physiological processes.

  18. Study of aerosol optical thickness using MODIS satellite data and sun photometer in a part of West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, R.K.; Suresh, T.; Govindaraju; Urs, J.R.; SureshKumar, B.V.

    distribution geo location file which contains latitudes and longitudes. Level 1A is processed to get the Level 1B file, it will check for meteorological, ozone, and other files for necessary data. Level 1B file is processed to get Level 2 file, and finally...

  19. ULTRASPEC: a high-speed imaging photometer on the 2.4-m Thai National Telescope

    CERN Document Server

    Dhillon, V S; Atkinson, D C; Bezawada, N; Bours, M C P; Copperwheat, C M; Gamble, T; Hardy, L K; Hickman, R D H; Irawati, P; Ives, D J; Kerry, P; Leckngam, A; Littlefair, S P; McLay, S A; O'Brien, K; Peacocke, P T; Poshyachinda, S; Richichi, A; Soonthornthum, B; Vick, A

    2014-01-01

    ULTRASPEC is a high-speed imaging photometer mounted permanently at one of the Nasmyth focii of the 2.4-m Thai National Telescope (TNT) on Doi Inthanon, Thailand's highest mountain. ULTRASPEC employs a 1024x1024 pixel frame-transfer, electron-multiplying CCD (EMCCD) in conjunction with re-imaging optics to image a field of 7.7'x7.7' at (windowed) frame rates of up to ~200 Hz. The EMCCD has two outputs - a normal output that provides a readout noise of 2.3 e- and an avalanche output that can provide essentially zero readout noise. A six-position filter wheel enables narrow-band and broad-band imaging over the wavelength range 330-1000 nm. The instrument saw first light on the TNT in November 2013 and will be used to study rapid variability in the Universe. In this paper we describe the scientific motivation behind ULTRASPEC, present an outline of its design and report on its measured performance on the TNT.

  20. The Multicolor Panoramic Photometer-Polarimeter with high time resolution based on the PSD

    CERN Document Server

    Plokhotnichenko, V L; Debur, V; Panferov, A A; Panferova, I

    2003-01-01

    Multicolor Panoramic Photometer-Polarimeter (MPPP) with a time resolution of 1 microsecond has been built based on a PSD and used at the 6-meter telescope in SAO (Russia). The device allows registration of the photon fluxes in four photometric bands simultaneously and finding values of 3 Stokes parameters. MPPP consists of Position-Sensitive Detector (PSD), acquisition MANIA-system, polarization unit and a set of dichroic filters. MPPP gives a possibility of detecting photons in 2 pupils with a size of 10 - 15 arc sec centered on the object and comparison star positions simultaneously. The first half of the object photon flux passes through the phase rotating plate and polarizer, and the second one through the polarizer alone. MPPP registers in each of the 4 filters four images of the object with different orientations of polarization plane and one image of a comparison star. It allows measuring instantaneous Stokes parameters. The main astrophysical problems to be solved with MPPP are as follows: investigati...

  1. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    Science.gov (United States)

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  2. Optimized method for black carbon analysis in ice and snow using the Single Particle Soot Photometer

    Directory of Open Access Journals (Sweden)

    I. A. Wendl

    2014-03-01

    Full Text Available In this study we attempt to optimize the method for measuring black carbon (BC in snow and ice using a single particle soot photometer (SP2. Beside the previously applied ultrasonic (CETAC and Collison-type nebulizers we introduce a jet (APEX-Q nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and APEX-Q require small sample volumes (few milliliters which makes them suitable for ice core analysis. The APEX-Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100–1000 nm. The CETAC has the advantage that air and liquid flows can be monitored continuously. All nebulizer-types require a calibration with BC standards for the determination of the BC mass concentration in unknown aqueous samples. We found Aquadag to be a suitable material for preparing calibration standards. Further, we studied the influence of different treatments for fresh discrete snow and ice samples as well as the effect of storage. The results show that samples are best kept frozen until analysis. Once melted, they should be sonicated for 25 min, immediately analyzed while being stirred and not be refrozen.

  3. Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. II. 70 micron Imaging

    CERN Document Server

    Gordon, Karl D; Fadda, Dario; Stansberry, John; Wachter, Stefanie; Frayer, Dave T; Rieke, George; Noriega-Crespo, Alberto; Latter, William B; Young, Erick; Neugebauer, Gerry; Balog, Zoltan; Dole, Herve; Egami, Eiichi; Hines, Dean; Kelly, Doug; Marleau, Francine; Misselt, Karl; Morrison, Jane; Perez-Gonzalez, Pablo; Rho, Jeonghee; Wheaton, Wm A

    2007-01-01

    The absolute calibration and characterization of the Multiband Imaging Photometer for Spitzer (MIPS) 70 micron coarse- and fine-scale imaging modes are presented based on over 2.5 years of observations. Accurate photometry (especially for faint sources) requires two simple processing steps beyond the standard data reduction to remove long-term detector transients. Point spread function (PSF) fitting photometry is found to give more accurate flux densities than aperture photometry. Based on the PSF fitting photometry, the calibration factor shows no strong trend with flux density, background, spectral type, exposure time, or time since anneals. The coarse-scale calibration sample includes observations of stars with flux densities from 22 mJy to 17 Jy, on backgrounds from 4 to 26 MJy sr^-1, and with spectral types from B to M. The coarse-scale calibration is 702 +/- 35 MJy sr^-1 MIPS70^-1 (5% uncertainty) and is based on measurements of 66 stars. The instrumental units of the MIPS 70 micron coarse- and fine-sca...

  4. Sun Safe Mode Controller Design for LADEE

    Science.gov (United States)

    Fusco, Jesse C.; Swei, Sean S. M.; Nakamura, Robert H.

    2015-01-01

    This paper presents the development of sun safe controllers which are designed to keep the spacecraft power positive and thermally balanced in the event an anomaly is detected. Employed by NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), the controllers utilize the measured sun vector and the spacecraft body rates for feedback control. To improve the accuracy of sun vector estimation, the least square minimization approach is applied to process the sensor data, which is proven to be effective and accurate. To validate the controllers, the LADEE spacecraft model engaging the sun safe mode was first simulated and then compared with the actual LADEE orbital fight data. The results demonstrated the applicability of the proposed sun safe controllers.

  5. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  6. Design and Fabrication of an Albedo Insensitive Analog Sun Sensor

    NARCIS (Netherlands)

    Wu, H.; Emadi, A.; De Graaf, G.; Leijtens, J.; Wolffenbuttel, R.F.

    2011-01-01

    A sun sensor is usually included in a satellite for optically measuring the position relative to the sun. The accuracy of a conventional sun sensor is affected by reflected sunlight at the nearby earth atmosphere: the albedo radiation. The part of the spectrum at near IR (1.5 μm) is not included in

  7. CEFLES2: the remote sensing component to quantify photosynthetic efficiency from the leaf to the region by measuring sun-induced fluorescence in the oxygen absorption bands

    Directory of Open Access Journals (Sweden)

    S. van der Linden

    2009-07-01

    Full Text Available The CEFLES2 campaign during the Carbo Europe Regional Experiment Strategy was designed to provide simultaneous airborne measurements of solar induced fluorescence and CO2 fluxes. It was combined with extensive ground-based quantification of leaf- and canopy-level processes in support of ESA's Candidate Earth Explorer Mission of the "Fluorescence Explorer" (FLEX. The aim of this campaign was to test if fluorescence signal detected from an airborne platform can be used to improve estimates of plant mediated exchange on the mesoscale. Canopy fluorescence was quantified from four airborne platforms using a combination of novel sensors: (i the prototype airborne sensor AirFLEX quantified fluorescence in the oxygen A and B bands, (ii a hyperspectral spectrometer (ASD measured reflectance along transects during 12 day courses, (iii spatially high resolution georeferenced hyperspectral data cubes containing the whole optical spectrum and the thermal region were gathered with an AHS sensor, and (iv the first employment of the high performance imaging spectrometer HYPER delivered spatially explicit and multi-temporal transects across the whole region. During three measurement periods in April, June and September 2007 structural, functional and radiometric characteristics of more than 20 different vegetation types in the Les Landes region, Southwest France, were extensively characterized on the ground. The campaign concept focussed especially on quantifying plant mediated exchange processes (photosynthetic electron transport, CO2 uptake, evapotranspiration and fluorescence emission. The comparison between passive sun-induced fluorescence and active laser-induced fluorescence was performed on a corn canopy in the daily cycle and under desiccation stress. Both techniques show good agreement in detecting stress induced fluorescence change at the 760 nm band. On the large scale, airborne and ground-level measurements of fluorescence

  8. CEFLES2: the remote sensing component to quantify photosynthetic efficiency from the leaf to the region by measuring sun-induced fluorescence in the oxygen absorption bands

    Directory of Open Access Journals (Sweden)

    U. Rascher

    2009-02-01

    Full Text Available The CEFLES2 campaign during the Carbo Europe Regional Experiment Strategy was designed to provide simultaneous airborne measurements of solar induced fluorescence and CO2 fluxes. It was combined with extensive ground-based quantification of leaf- and canopy-level processes in support of ESA's Candidate Earth Explorer Mission of the "Fluorescence Explorer" (FLEX. The aim of this campaign was to test if fluorescence signal detected from an airborne platform can be used to improve estimates of plant mediated exchange on the mesoscale. Canopy fluorescence was quantified from four airborne platforms using a combination of novel sensors: (i the prototype airborne sensor AirFLEX quantified fluorescence in the oxygen A and B bands, (ii a hyperspectral spectrometer (ASD measured reflectance along transects during 12 day courses, (iii spatially high resolution georeferenced hyperspectral data cubes containing the whole optical spectrum and the thermal region were gathered with an AHS sensor, and (iv the first employment of the high performance imaging spectrometer HYPER delivered spatially explicit and multi-temporal transects across the whole region. During three measurement periods in April, June and September 2007 structural, functional and radiometric characteristics of more than 20 different vegetation types in the Les Landes region, Southwest France, were extensively characterized on the ground. The campaign concept focussed especially on quantifying plant mediated exchange processes (photosynthetic electron transport, CO2 uptake, evapotranspiration and fluorescence emission. The comparison between passive sun-induced fluorescence and active laser-induced fluorescence was performed on a corn canopy in the daily cycle and under desiccation stress. Both techniques show good agreement in detecting stress induced fluorescence change at the 760 nm band. On the large scale, airborne and ground-level measurements of fluorescence

  9. FIREX-Related Biomass Burning Research Using ARM Single-Particle Soot Photometer Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Onasch, Timothy B [Aerodyne Research, Inc.; Sedlacek, Arthur J [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-03-15

    The scientific focus of this study was to investigate and quantify the mass loadings, chemical compositions, and optical properties of biomass burning particulate emissions generated in the laboratory from Western U.S. fuels using a similar instrument suite to the one deployed on the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility Gulfstream-1 (G-1) aircraft during the 2013 Biomass Burning Observation Project (BBOP) field study (Kleinman and Sedlacek, 2013). We deployed the single-particle soot photometer (SP2) to make measurements of biomass burning refractory black carbon (rBC) mass loadings and size distributions to correlate with non-refractory particulate matter (NR-PM; i.e., HR-AMS) and rBC (SP-AMS) measurements as a function of photo-oxidation processes in an environmental chamber. With these measurements, we will address the following scientific questions: 1. What are the emission indices (g/kg fuel) of rBC from various wildland fuels from the Pacific Northwest (i.e., relevant to BBOP analysis) as a function of combustion conditions and simulated atmospheric processing in an environmental chamber? 2. What are the optical properties (e.g., mass-specific absorption cross-section [MAC], single-scattering albedo [SSA], and absorption Angstrom exponent [AAE)] of rBC emitted from various wildland fuels and how are they impacted by atmospheric processing? 3. How does the mixing state of rBC in biomass-burning plumes relate to the optical properties? 4. How does the emitted rBC affect radiative forcing?

  10. Total eclipses of the sun.

    Science.gov (United States)

    Zirker, J B

    1980-12-19

    Total eclipses of the sun offer research opportunities in a variety of sciences. Some of the advances in solar physics resulting from eclipse observations are discussed. Experiments at the total eclipse of 16 February 1980 in India are also described. These included a test of general relativity, studies in coronal physics, investigations of solar prominences, diameter measurements, a search for interplanetary dust, a study of the gravity waves in the earth's atmosphere, and experiments on the biological effects on animals and humans.

  11. Stabilization of Mass Absorption Cross Section of Elemental Carbon for Filter-Based Absorption Photometer by Heated Inlet

    Science.gov (United States)

    Kondo, Y.; Sahu, L.; Takegawa, N.; Miyazaki, Y.; Han, S.; Moteki, N.; Hu, M.; Kim Oanh, N.; Kim, Y.

    2008-12-01

    Accurate measurements of elemental carbon (EC) or black carbon on a long-term basis are important for the studies of impacts of EC on climate and human health. In principle, mass concentrations of EC (MEC) can be estimated by the measurement of light absorption coefficient by EC. Filter-based methods, which quantify the absorption coefficient (kabs) from the change in transmission through a filter loaded with particles, have been widely used to measure MEC because of the ease of the operation. However, in practice, reliable determination of MEC has been very difficult because of the large variability in the mass absorption cross sections (Cabs), which is a conversion factor from kabs to MEC. Coating of EC by volatile compounds and co-existence of light-scattering particles greatly contributes to the variability of Cabs. In order to overcome this difficulty, volatile aerosol components were removed before collection of EC particles on filters by heating an inlet section to 400°C. The heated inlet vaporized almost completely sulfate, nitrate, ammonium, and organics without any detectable loss of EC. Simultaneous measurements of kabs by two types photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with MEC by the EC-OC analyzer were made to determine Cabs at 6 different locations in Asia (Japan, Korea, China, and Thailand) in different seasons. The Cabs was stable to be 10.5±0.7 m2 g-1 at the wavelength of 565 nm for EC strongly impacted by emissions from vehicles and biomass burning. The stability of the Cabs for different EC sources and under the different physical and chemical conditions provides a firm basis for its use in estimating MEC in fine mode with an accuracy of about 10%.

  12. Sun and Sjogren's Syndrome

    Science.gov (United States)

    Patient Education Sheet The Sun and Sjögren’s Syndrome The SSF thanks Mona Z. Mofid, MD, FAAD, Diplomate, American Board of Dermatology, and Medical Director, American Melanoma Foundation, San Diego, California, ...

  13. Direct sun and airborne MAX-DOAS measurements of the collision induced oxygen complex, O2O2 absorption with significant pressure and temperature differences

    Directory of Open Access Journals (Sweden)

    E. Spinei

    2014-09-01

    Full Text Available The collision induced O2 complex, O2O2, is a very important trace gas in remote sensing measurements of aerosol and cloud properties. Some ground based MAX-DOAS measurements of O2O2 slant column density require correction factors of 0.75 ± 0.1 to reproduce radiative transfer modeling (RTM results for a near pure Rayleigh atmosphere. One of the potential causes of this discrepancy is believed to be uncertainty in laboratory measured O2O2 absorption cross section temperature and pressure dependence, due to difficulties in replicating atmospheric conditions in the laboratory environment. This paper presents direct-sun (DS and airborne multi-axis (AMAX DOAS measurements of O2O2 absorption optical depths under actual Earth atmospheric conditions in two wavelength regions (335–390 nm and 435–490 nm. DS irradiance measurements were made by the research grade MFDOAS instrument from 2007–2014 at seven sites with significant pressure (778–1013 hPa and O2O2 profile weighted temperature (247–275 K differences. Aircraft MAX-DOAS measurements were conducted by the University of Colorado AMAX-DOAS instrument on 29 January 2012 over the Southern Hemisphere subtropical Pacific Ocean. Scattered solar radiance spectra were collected at altitudes between 9 and 13.2 km, with O2O2 profile weighted temperatures of 231–244 K, and near pure Rayleigh scattering conditions. Due to the well defined DS air mass factors and extensively characterized atmospheric conditions during the AMAX-DOAS measurements, O2O2"pseudo" absorption cross sections, σ, are derived from the observed optical depths and estimated O2O2column densities. Vertical O2O2 columns are calculated from the atmospheric sounding temperature, pressure and specific humidity profiles. Based on the atmospheric DS observations, there is no pressure dependence of the O2O2 σ, within the measurement errors (3%. The two data sets are combined to derive peak σ temperature dependence of 360 and 477 nm

  14. Sun behaviour after cutaneous malignant melanoma

    DEFF Research Database (Denmark)

    Idorn, L W; Datta, P; Heydenreich, J

    2013-01-01

    Background  It has been reported that patients with cutaneous malignant melanoma (CMM) can lower their risk of a second primary melanoma by limiting recreational sun exposure. Previous studies based on questionnaires and objective surrogate measurements indicate that before their diagnosis......, patients with CMM are exposed to higher ultraviolet radiation (UVR) doses than controls, followed by a reduction after diagnosis. Objectives  In a prospective, observational case-control study, we aimed to assess sun exposure after diagnosis of CMM by objective measurements to substantiate advice about sun...... months and 6 years before the start of the study. During a summer season participants filled in sun exposure diaries daily and wore personal electronic UVR dosimeters in a wristwatch that continuously measured time-stamped UVR doses in standard erythema dose. Results  The UVR dose of recently diagnosed...

  15. Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the Sky

    Science.gov (United States)

    Mims, Forrest M., III; Chambers, Lin H.; Brooks, David R.

    2011-01-01

    A 2-year study affirms that the temperature (Tz) indicated by an inexpensive ($20 to $60) IR thermometer pointed at the cloud-free zenith sky provides an approximate indication of the total column water vapor (precipitable water or PW). PW was measured by a MICROTOPS II sun photometer. The coefficient of correlation (r2) of the PW and Tz was 0.90, and the rms difference was 3.2 mm. A comparison of the Tz data with the PW provided by a GPS site 31 km NNE yielded an r2 of 0.79, and an rms difference of 5.8 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site and 10 days at Hawaii's Mauna Loa Observatory (MLO). The best results of this comparison were provided by two IR thermometers models that yielded an r2 of 0.96 and an rms difference with the PW of 2.7 mm. The results of both the ongoing 2-year study and the 5-month instrument comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, the accuracy typically ascribed to sun photometers.

  16. Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the Sky

    Science.gov (United States)

    Mims, Forrest M., III; Chambers, Lin H.; Brooks, David R.

    2011-01-01

    A 2-year study affirms that the temperature (Tz) indicated by an inexpensive ($20 to $60) IR thermometer pointed at the cloud-free zenith sky provides an approximate indication of the total column water vapor (precipitable water or PW). PW was measured by a MICROTOPS II sun photometer. The coefficient of correlation (r2) of the PW and Tz was 0.90, and the rms difference was 3.2 mm. A comparison of the Tz data with the PW provided by a GPS site 31 km NNE yielded an r2 of 0.79, and an rms difference of 5.8 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site and 10 days at Hawaii's Mauna Loa Observatory (MLO). The best results of this comparison were provided by two IR thermometers models that yielded an r2 of 0.96 and an rms difference with the PW of 2.7 mm. The results of both the ongoing 2-year study and the 5-month instrument comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, the accuracy typically ascribed to sun photometers.

  17. Why Study the Sun?

    Indian Academy of Sciences (India)

    Arvind Bhatnagar

    2006-06-01

    In this presentation we briefly describe the Sun through large number of illustrations and pictures of the Sun taken from early times to the present day space missions. The importance of the study of the Sun is emphasized as it is the nearest star which presents unparallelled views of surface details and numerous phenomena. Our Sun offers a unique celestial laboratory where a large variety of phenomena take place, ranging in temporal domain from a few milliseconds to several decades, in spatial domain from a few hundred kilometers to thousands of kilometers, and in the temperature domain from a few thousand degrees to several million degrees. Its mass motion ranges from thousandths to thousands of kilometers per second. Such an object provides us with a unique laboratory to study the state of matter in the Universe. The existing solar ground-based and space missions have already revealed several mysteries of the outer environment of our Sun and much more is going to come in the near future from planned new sophisticated ground-based solar telescopes and Space missions. The new technique of helioseismology has unravelled many secrets of the solar interior and has put the Standard Solar Model (SSM) on firm footing. The long-standing problem of solar neutrinos has been recently sorted out, and even the ‘back side’ view of the Sun can be seen using the technique of holographic helioseismology.

  18. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  19. EUV SpectroPhotometer (ESP) in Extreme Ultraviolet Variability Experiment (EVE): Algorithms and Calibrations

    Science.gov (United States)

    Didkovsky, L.; Judge, D.; Wieman, S.; Woods, T.; Jones, A.

    2012-01-01

    The Extreme ultraviolet SpectroPhotometer (ESP) is one of five channels of the Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO). The ESP channel design is based on a highly stable diffraction transmission grating and is an advanced version of the Solar Extreme ultraviolet Monitor (SEM), which has been successfully observing solar irradiance onboard the Solar and Heliospheric Observatory (SOHO) since December 1995. ESP is designed to measure solar Extreme UltraViolet (EUV) irradiance in four first-order bands of the diffraction grating centered around 19 nm, 25 nm, 30 nm, and 36 nm, and in a soft X-ray band from 0.1 to 7.0 nm in the zeroth-order of the grating. Each band’s detector system converts the photo-current into a count rate (frequency). The count rates are integrated over 0.25-second increments and transmitted to the EVE Science and Operations Center for data processing. An algorithm for converting the measured count rates into solar irradiance and the ESP calibration parameters are described. The ESP pre-flight calibration was performed at the Synchrotron Ultraviolet Radiation Facility of the National Institute of Standards and Technology. Calibration parameters were used to calculate absolute solar irradiance from the sounding-rocket flight measurements on 14 April 2008. These irradiances for the ESP bands closely match the irradiance determined for two other EUV channels flown simultaneously: EVE’s Multiple EUV Grating Spectrograph (MEGS) and SOHO’s Charge, Element and Isotope Analysis System/ Solar EUV Monitor (CELIAS/SEM).

  20. Effects of motives on reactions to safe sun messages.

    Science.gov (United States)

    Aspden, Trefor; Ingledew, David K; Parkinson, John A

    2015-01-01

    We investigated whether appearance motive for sun exposure, which strongly predicts exposure behaviour, would predict reactions to safe sun messages. In a survey with an embedded experiment, 245 individuals completed measures of motives, read a safe sun message framed by incentive (appearance/health), tone (directive/nondirective) and valence (gain/loss), then completed measures of reactions. For participants high in appearance motive, an appearance-nondirective message was most persuasive. Regardless of individual's appearance motive, appearance messages produced lower reactance if phrased using nondirective language. To maximise persuasion and minimise reactance in individuals most motivated to sun expose, safe sun messages should focus on appearance using nondirective language.

  1. Perspectives on the Interior of the Sun

    Indian Academy of Sciences (India)

    S. Μ. Chitre

    2000-09-01

    The interior of the Sun is not directly accessible to observations. Nonetheless, it is possible to infer the physical conditions inside the Sun with the help of structure equations governing its equilibrium and with the powerful observational tools provided by the neutrino fluxes and oscillation frequencies. The helioseismic data show that the internal constitution of the Sun can be adequately represented by a standard solar model. It turns out that a cooler solar core is not a viable solution for the measured deficit of neutrino fluxes, and the resolution of the solar neutrino puzzle should be sought in the realm of particle physics.

  2. The Jovian period in the Sun?

    Science.gov (United States)

    Kotov, V. A.

    2015-09-01

    The 41-year measurements of the Doppler effect of the photosphere performed at the Crimean Astrophysical Observatory, discovered two periods of global oscillations of the Sun: 9600.606(12) s and 9597.929(15) s. Their beat period, 398.4(2.9) d, well agrees with a synodic orbital period of Jupiter, PJ = 398.9 d, raising a new problem for solar physics, cosmogony and cosmology. A hypothesis is advanced that the PJ beating of the Sun is induced by gravitation of Jupiter, revolving in a privileged reference system "the Sun - the Earth".

  3. Development of photomultiplier electronics and computer interfacing software for a high speed photoelectric photometer-Stoke's meter

    Science.gov (United States)

    Flesch, T. R.

    1982-01-01

    Preliminary stages in the design, construction, and development of a photoelectric photometer system interfaced with an IMSAI 8080 microcomputer. The instrument will also include magnetic tape and magnetic disk storage capabilities to enable rapid data storage. The capability of the instrument to make observations with very high time resolution, as high as 10 msec, and measure the intensity and polarization of radiation emitted by objects which show very rapid light variations, pulsars and optical counterparts of X-ray sources was of concern. A better understanding of the magnetic fields and interstellar material which characterize the immediate environment of these stellar systems and an expansion of the observational capabilities of even modest-sized telescopes are expected.

  4. Build Your Own Photometer: A Guided-Inquiry Experiment to Introduce Analytical Instrumentation

    Science.gov (United States)

    Wang, Jessie J.; Nun´ez, Jose´ R. Rodríguez; Maxwell, E. Jane; Algar, W. Russ

    2016-01-01

    A guided-inquiry project designed to teach students the basics of spectrophotometric instrumentation at the second year level is presented. Students design, build, program, and test their own single-wavelength, submersible photometer using low-cost light-emitting diodes (LEDs) and inexpensive household items. A series of structured prelaboratory…

  5. A Near-Infrared Photometer for the Laboratorio Nacional de Astrofisica

    Science.gov (United States)

    Lepine, J. R. D.; Gneiding, C.; Laporte, R.; Dias, A. O.; Epchtein, N.

    1990-11-01

    ABSTRACT. A near-infrared photometer has been constructed with an InSb photovoltaic detector. At present, we dispose of two filters for bands H (1.6 m) and K (2.2 ijm). The acquisition of data is made using a IBMXT microcomputer. Keq o'td : INSTRUMENTS - PHOTOMETRY

  6. Lessons from the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2011-07-01

    Full Text Available In this brief note, the implications of a condensed Sun will be examined. A celestial body composed of liquid metallic hydrogen brings great promise to astronomy, relative to understanding thermal emission and solar structure. At the same time, as an incom- pressible liquid, a condensed Sun calls into question virtually everything which is cur- rently believed with respect to the evolution and nature of the stars. Should the Sun be condensed, then neutron stars and white dwarfs will fail to reach the enormous densities they are currently believed to possess. Much of cosmology also falls into question, as the incompressibility of matter curtails any thought that a primordial atom once existed. Aging stars can no longer collapse and black holes will know no formative mechanism. A condensed Sun also hints that great strides must still be made in understanding the nature of liquids. The Sun has revealed that liquids possess a much greater potential for lattice order than previously believed. In addition, lessons may be gained with regards to the synthesis of liquid metallic hydrogen and the use of condensed matter as the basis for initiating fusion on Earth.

  7. Sun exposure and protection behavior of Danish farm children

    DEFF Research Database (Denmark)

    Bodekær, Mette; Øager Petersen, Bibi; Philipsen, Peter Alshede

    2014-01-01

    Healthy sun habits acquired in childhood could reduce skin cancer incidence. We examined the sun exposure and protection behavior of an expected high-exposure group of children, and the association to their parents. Open, prospective cohort study. One hundred and thirty nine participants (40...... families) kept daily sun behavior diaries (sun exposure, sunscreen use, sunburns) over a 4-month summer period (15,985 diary days). The Pigment Protection Factor (PPF), an objective measure of sun exposure, was measured at two body sites, before and after summer. All participants presented data from...... the same 115 days. Risk behavior (sun exposure of upper body) took place on 9.5 days (boys) and 15.6 days (girls). Sunburn and sunscreen use were infrequent. Boys' sun exposure resulted in an increased photo protection over the study period of 1.7 SED (upper arm) and 0.8 SED (shoulder) to elicit erythema...

  8. On Flare-CME Characteristics from Sun to Earth Combining Remote-Sensing Image Data with In Situ Measurements Supported by Modeling

    Science.gov (United States)

    Temmer, Manuela; Thalmann, Julia K.; Dissauer, Karin; Veronig, Astrid M.; Tschernitz, Johannes; Hinterreiter, Jürgen; Rodriguez, Luciano

    2017-07-01

    We analyze the well-observed flare and coronal mass ejection (CME) from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of effects - from Sun to Earth - to better understand the dynamic evolution of the CME and its embedded magnetic field. We study in detail the solar surface and atmosphere associated with the flare and CME using the Solar Dynamics Observatory (SDO) and ground-based instruments. We also track the CME signature off-limb with combined extreme ultraviolet (EUV) and white-light data from the Solar Terrestrial Relations Observatory (STEREO). By applying the graduated cylindrical shell (GCS) reconstruction method and total mass to stereoscopic STEREO-SOHO ( Solar and Heliospheric Observatory) coronagraph data, we track the temporal and spatial evolution of the CME in the interplanetary space and derive its geometry and 3D mass. We combine the GCS and Lundquist model results to derive the axial flux and helicity of the magnetic cloud (MC) from in situ measurements from Wind. This is compared to nonlinear force-free (NLFF) model results, as well as to the reconnected magnetic flux derived from the flare ribbons (flare reconnection flux) and the magnetic flux encompassed by the associated dimming (dimming flux). We find that magnetic reconnection processes were already ongoing before the start of the impulsive flare phase, adding magnetic flux to the flux rope before its final eruption. The dimming flux increases by more than 25% after the end of the flare, indicating that magnetic flux is still added to the flux rope after eruption. Hence, the derived flare reconnection flux is most probably a lower limit for estimating the magnetic flux within the flux rope. We find that the magnetic helicity and axial magnetic flux are lower in the interplanetary space by ˜ 50% and 75%, respectively, possibly indicating an erosion process. A CME mass increase of 10% is observed over a range of {˜} 4 - 20 R_{⊙}. The temporal evolution of the CME

  9. Magnetohydrodynamics of the sun

    CERN Document Server

    Priest, Eric

    2014-01-01

    Magnetohydrodynamics of the Sun is a completely new up-to-date rewrite from scratch of the 1982 book Solar Magnetohydrodynamics, taking account of enormous advances in understanding since that date. It describes the subtle and complex interaction between the Sun's plasma atmosphere and its magnetic field, which is responsible for many fascinating dynamic phenomena. Chapters cover the generation of the Sun's magnetic field by dynamo action, magnetoconvection and the nature of photospheric flux tubes such as sunspots, the heating of the outer atmosphere by waves or reconnection, the structure of prominences, the nature of eruptive instability and magnetic reconnection in solar flares and coronal mass ejections, and the acceleration of the solar wind by reconnection or wave-turbulence. It is essential reading for graduate students and researchers in solar physics and related fields of astronomy, plasma physics and fluid dynamics. Problem sets and other resources are available at www.cambridge.org/9780521854719.

  10. The Sun's Supergranulation

    CERN Document Server

    Rieutord, Michel

    2010-01-01

    The Sun's supergranulation refers to a physical pattern covering the surface of the quiet Sun with a typical horizontal scale of approximately 30000km. Its most noticeable observable signature is as a fluctuating velocity field whose components are mostly horizontal. Supergranulation was discovered more than fifty years ago, however explaining why and how it originates still represents one of the main challenges of modern solar physics. A lot of work has been devoted to the subject over the years, but observational constraints, conceptual difficulties and numerical limitations have all concurred to prevent a detailed understanding of the supergranulation phenomenon so far. With the advent of 21st century supercomputing resources and the availability of unprecedented high-resolution observations of the Sun, the solar community has now reached a stage at which key progress can be made on this question. A unifying strategy between observations and modeling is more than ever required for this to be possible. The ...

  11. Sun, Earth and Sky

    Science.gov (United States)

    Lang, Kenneth R.

    1995-01-01

    The Sun is enveloped by a hot, tenuous million-degree corona that expands to create a continuous solar wind that sweeps past all the planets and fills the heliosphere. The solar wind is modulated by strong gusts that are initiated by powerful explosions on the Sun, including solar flares and coronal mass ejections. This dynamic, invisible outer atmosphere of the Sun is currently under observation with the soft X-ray telescope aboard the Yohkoh spacecraft, whose results are presented. We also show observations from the Ulysses spacecraft that is now passing over the solar pole, sampling the solar wind in this region for the first time. Two other spacecraft, Voyager 1 and 2, have recently detected the outer edge of the invisible heliosphere, roughly halfway to the nearest star. Magnetic solar activity, the total radiative output from the Sun, and the Earth's mean global surface temperature all vary with the 11-year sunspot cycle in which the total number of sunspots varies from a maximum to a minimum and back to a maximum again in about 11 years. The terrestrial magnetic field hollows out a protective magnetic cavity, called the magnetosphere, within the solar wind. This protection is incomplete, however, so the Sun feeds an unseen world of high-speed particles and magnetic fields that encircle the Earth in space. These particles endanger spacecraft and astronauts, and also produce terrestrial aurorae. An international flotilla of spacecraft is now sampling the weak points in this magnetic defense. Similar spacecraft have also discovered a new radiation belt, in addition to the familiar Van Allen belts, except fed by interstellar ions instead of electrons and protons from the Sun.

  12. Piece of the sun

    CERN Document Server

    Wayne, Teddy

    2015-01-01

    Our rapidly industrialising world has an insatiable hunger for energy, and conventional sources are struggling to meet demand. Oil is running out, coal is damaging our climate, many nations are abandoning nuclear, yet solar, wind and water will never be a complete replacement. The solution, says Daniel Clery in this deeply researched and revelatory book, is to be found in the original energy source: the Sun itself. There, at its centre, the fusion of 630 million tonnes of hydrogen every second generates an unfathomable amount of energy. By replicating even a tiny piece of the Sun's power

  13. Near-Sun asteroids

    Science.gov (United States)

    Emel'yanenko, V. V.

    2017-01-01

    As follows from dynamical studies, in the course of evolution, most near-Earth objects reach orbits with small perihelion distances. Changes of the asteroids in the vicinity of the Sun should play a key role in forming the physical properties, size distribution, and dynamical features of the near-Earth objects. Only seven of the discovered asteroids are currently moving along orbits with perihelion distances q orbits farther from the Sun. In this study, we found asteroids that have been recently orbiting with perihelion distances q orbits for hundreds to tens of thousands of years. To carry out astrophysical observations of such objects is a high priority.

  14. The SUN S TRAVELS

    Institute of Scientific and Technical Information of China (English)

    Robert; Louis; Stevenson

    2005-01-01

    The sun is not a-bed, when I At night upon my pillow lie; Stilt round the earth his Way he takes, And morning after morning makes. White here at home, in shining day, We round the sunny garden play, Each tittle Indian sleepy - head Is being kissed and put to bed. And When at eve I rise from tea, Day dawns beyond the Atlantic Sea; And all the children in the West Are getting up and being dressed.The SUN'S TRAVELS@Robert Louis Stevenson

  15. Possible measurements of J sub 2 and the sun's angular momentum with the solar probe. [covariance analysis of solar quadrupole moment

    Science.gov (United States)

    Nordtvedt, K.

    1978-01-01

    The metric tensor is given for describing the dynamical effects of the sun on a solar probe and the gravitational redshift of a probe-based clock in a covariance analysis for the detectability of the solar quadrupole moment and the solar angular momentum. Unknown parameters were determined by least squares fit to the probe tracking data. A polar orbit was assumed with perihelion at 5 solar radii and with an earth-sun-probe angle of 135 deg at perihelion. Tracking was assumed to be Doppler only, with a basic uncertainity of .1 mm/sec in the radial velocity. A drag-free system which could reduce nongravitational forces below the level of 2 times 10 to the minus 12th power was found necessary to preserve this same level of accuracy. Both one way and two way Doppler were supposed in order to determine the gravitational redshift as well as the pure spacecraft dynamics.

  16. Calibration of a Micronal flame photometer model B-260. Intercomparison of the analytical results for potassium; Calibracao de um fotometro de chama micronal modelo B-260. Intercomparacao de resultados analiticos de potassio

    Energy Technology Data Exchange (ETDEWEB)

    Alencar, Lucia Maria Laboissiere; Dalston, Regina Celia Reboucas

    1983-12-31

    In its environmental monitoring program, NUCLEBRAS analyzes systematically environmental samples in order to determine the total alpha and beta activities. In most of these samples, {sup 40} K is present in measurable quantities and can therefore be used for measuring beta activity since it is almost a 100% beta emitter. A method using a flame photometer for measuring the potassium concentration in water is presented. 5 refs., 28 figs., 25 tabs.

  17. Maximising the sun

    CSIR Research Space (South Africa)

    Conradie, Dirk CU

    2010-08-01

    Full Text Available South Africa is blessed with some of the best quality solar radiation in the world. In the light of this many exciting opportunities exist to utilize the sun to its full potential in the design of energy efficient buildings. Passive solar buildings...

  18. Sun Ultra 5

    CERN Multimedia

    1998-01-01

    The Sun Ultra 5 is a 64-bit personal computer based on the UltraSPARC microprocessor line at a low price. The Ultra 5 has been declined in several variants: thus, some models have a processor with less cache memory to further decrease the price of the computer.

  19. The Toboggan Sun

    NARCIS (Netherlands)

    Davidson, WPS; van der Werf, SY

    2005-01-01

    Special variants of the Novaya Zemlya effect may arise from localized temperature inversions that follow the height profile of hills or mountains. Rather than following its natural path, the rising or setting Sun may, under such circumstances, appear to slide along a distant mountain slope. We found

  20. Go Sun Smart

    Science.gov (United States)

    Scott, Michael D.; Buller, David B.; Walkosz, Barbara J.; Andersen, Peter A.; Cutter, Gary R.; Dignan, Mark B.

    2008-01-01

    This is the story of Go Sun Smart, a worksite wellness program endorsed by the North American Ski Area Association and funded by the National Cancer Institute. Between 2000 and 2002 we designed and implemented a large-scale worksite intervention at over 300 ski resorts in North America with the objective of reducing ski area employees and guests…

  1. Our Explosive Sun

    Science.gov (United States)

    Brown, D. S.

    2009-01-01

    The Sun's atmosphere is a highly structured but dynamic place, dominated by the solar magnetic field. Hot charged gas (plasma) is trapped on lines of magnetic force that can snap like an elastic band, propelling giant clouds of material out into space. A range of ground-based and space-based solar telescopes observe these eruptions, particularly…

  2. Dust Measurements in the Coma of Comet 67P/Churyumov-Gerasimenko Inbound to the Sun Between 3.7 and 3.4 AU

    Science.gov (United States)

    Rotundi, Alessandra; Della Corte, Vincenzo; Fulle, Marco; Ferrari, Marco; Sordini, Roberto; Ivanovski, Stavro; Accolla, Mario; Lucarelli, Francesca; Zakharov, Vladimir; Mazzotta Epifani, Elena; López-Moreno, José J.; Rodríguez, Julio; Colangeli, Luigi; Palumbo, Pasquale; Bussoletti, Ezio; Crifo, Jean-Francois; Esposito, Francesca; Green, Simon F.; Grün, Eberhard; Lamy, Philippe L.

    2015-04-01

    data on grain speed and its optical cross section. The IS grain momentum measurement, when combined with the GDS detection time, provides a direct measurement of grain speed and mass. These combined measurements characterize single grain dust dynamics in the coma of 67P/CG. The first grain was detected on 1 August 2014 at 814 km from the comet nucleus. Between then and 13 Septem-ber 2014 GIADA detected 35 grains ranging in mass from ~ 5 x 10-10 to 8 x 10-8 kg. Including complementary data from the OSIRIS narrow angle camera, the dust mass loss was calculated over an additional three orders of magni-tude in mass, extending the ejected dust grain sizes up to 2 cm. Combined with data from the MIRO and the ROSINA instruments onboard Rosetta we find a dust/gas mass ratio of 4 +/- 2 averaged over the sunlit nucleus sur-face. The dust to gas ratio may change as the comet approaches closer to the Sun. Acknowledgments: GIADA was built by a consortium led by the Univ. Napoli "Parthenope" & INAF- Oss. Astr. Capodimonte, in collabo-ration with the Inst. de Astrofisica de Andalucia, Selex-ES, FI and SENER. GIADA is presently managed & operated by Ist. di Astrofisica e Planetologia Spaziali-INAF, IT. GIADA was funded and managed by the Agenzia Spaziale Italiana, IT, with the support of the Spanish Ministry of Education and Science MEC, ES. GIADA was developed from a PI proposal from the University of Kent; sci. & tech. contribution were pro-vided by CISAS, IT, Lab. d'Astr. Spat., FR, and Institutions from UK, IT, FR, DE and USA. We thank the RSGS/ESAC, RMOC/ESOC & Rosetta Project/ESTEC for their outstanding work. Science support provided was by NASA through the US Rosetta Project managed by the Jet Propulsion Laboratory/California Institute of Technology. GIADA calibrated data will be available through ESA's PSA web site(www.rssd.esa.int/index.php?project=PSA&page=in dex). We would like to thank Angioletta Coradini for her contribution as a GIADA Co-I. We thank the MIRO, OSIRIS and

  3. How to Observe the Sun Safely

    CERN Document Server

    Macdonald, Lee

    2012-01-01

    How to Observe the Sun Safely, Second Edition gives all the basic information and advice the amateur astronomer needs to get started in observing our own ever-fascinating star. Unlike many other astronomical objects, you do not need a large telescope or expensive equipment to observe the Sun. And it is possible to take excellent pictures of the Sun with today's low-cost digital cameras! This book surveys what is visible on the Sun and then describes how to record solar features and measure solar activity levels. There is also an account of how to use H-alpha and Calcium-K filters to observe and record prominences and other features of the solar chromosphere, the Sun's inner atmosphere. Because we are just entering a period of high activity on the Sun, following a long, quiet period, this is a great time to get involved with solar observing. Still emphasizing safety first, this Second Edition reflects recent and exciting advances in solar observing equipment. Chapters 6 through 8 have been completely revised ...

  4. Stars resembling the Sun

    Science.gov (United States)

    Cayrel de Strobel, G.

    This review is primarily directed to the question whether photometric solar analogues remain such when subjected to detailed spectroscopic analyses and interpreted with the help of internal stucture models. In other words, whether the physical parameters: mass, chemical composition, age (determining effective temperature and luminosity), chromospheric activity, equatorial rotation, lithium abundance, velocity fields etc., we derive from the spectral analysis of a photometric solar analogue, are really close to those of the Sun. We start from 109 photometric solar analogues extracted from different authors. The stars selected had to satisfy three conditions: i) their colour index (B-V) must be contained in the interval: Δ (B-V) = 0.59-0.69, ii) they must possess a trigonometric parallax, iii) they must have undergone a high resolution detailed spectroscopic analysis. First, this review presents photometric and spectrophotometric researches on solar analogues and recalls the pionneering work on these stars by the late Johannes Hardorp. After a brief discussion on low and high resolution spectroscopic researches, a comparison is made between effective temperatures as obtained, directly, from detailed spectral analyses and those obtained, indirectly, from different photometric relations. An interesting point in this review is the discussion on the tantalilizing value of the (B-V)solar of the Sun, and the presentation of a new reliable value of this index. A short restatement of the kinematic properties of the sample of solar analogues is also made. And, finally, the observational ( T eff, M bol) diagram, obtained with 99 of the initially presented 109 analogues, is compared to a theoretical ( T eff, M bol) diagram. This latter has been constructed with a grid of internal structure models for which, (very important for this investigation), the Sun was used as gauge. In analysing the position, with respect to the Sun, of each star we hoped to find a certain number of

  5. Sun exposure and sun protection practices of children and their parents.

    LENUS (Irish Health Repository)

    Kiely, A D

    2009-05-01

    The primary aims of this study were: to estimate sun exposure in hours of children in Cork during the summer months; to examine sun protection measures used by children and their parents and to explore parental knowledge of sun exposure and protection. A cross-sectional study, using a semi-structured questionnaire, was conducted in June 2006 in primary schools, pre-schools and creches throughout Cork City and County. Parents of 250 children aged less than 12 years were sampled. Mean sun exposure of Cork children was 40.9 hours per week in the summer months, with 77 (46.1%) children developing sunburn. 59.3% of the studied children were of skin type 1 or 2. 95 (57%) children on weekdays and 137 (82%) children at weekends were exposed to the sun between 11 am and 3 pm. Sunscreen and hats\\/caps were the most common protection measures used. A minority used protective clothing, sunglasses or sought shade. Thirty one (30.5%) children had sunscreen reapplied every 2 hours. Knowledge of sun protection was considerable among Irish parents. However the frequency of sunburn among Irish children suggests we are not providing them with adequate sun protection.

  6. Optical performance analysis and test results of the EUCLID near-infrared spectro-photometer

    Science.gov (United States)

    Gal, C.; Thiele, H.; Gubbini, E.; Mecsaci, A.; Kuisl, A.; Meister, A.; Mottaghibonab, A.; Gawlik, K.; Dubowy, M.; Grupp, F.; Bode, A.; Wimmer, C.; Bender, R.

    2016-07-01

    The Near Infrared Spectrometer and Photometer (NISP) of the EUCLID satellite project encompasses high precision large lens mounts of 168 mm diameter that are operated at cryogenic temperatures down to 135K. The four lenses of the optical system are made of different materials: SUPRASIL 30001, CaF2, and S-FTM16, which are mounted in a separate lens mount design using glue connections. Each lens assembly has its individual mechanical interface to the structure, the so called lens barrel. Exhaustive structural and thermal investigations have determined lens surface deformations and lens position changes that are introduced by various environmental loads, such as thermal-, mechanical-, interface-, and gravity loads, as well as mechanical stress of the lenses due to glue shrinkage during curing. All these impacts change the lens optical behaviours under real operational conditions of the optical assembly, which are thoroughly investigated in the optical performance assessment activity. Especially, great effort has been made for the simulation of interface tolerances. Due to the complexity of all mechanical interfaces (baffle, lens mounts, housing, telescope structure, etc.) statistical simulation is conducted applying Monte Carlo method. From the result of the statistical simulation 3 representative cases are selected for the optical performance assessment, which have 95% confidence level of the lens surface deformation. In the context of the evaluation procedure the surface form error of all EUCLID lenses as well as the RMS WFE at the focal plane is assessed, and results are compared with the nominal performance of the system, as well as with interferometrically measured results achieved during the interface- and gravity release test campaign. The performance of the lens holder design in terms of glue shrinkage effects, gravity release and interface tolerances is verified by an adapted test facility including an interferometer based optical metrology system. Finally

  7. Input-output Transfer Function Analysis of a Photometer Circuit Based on an Operational Amplifier.

    Science.gov (United States)

    Hernandez, Wilmar

    2008-01-09

    In this paper an input-output transfer function analysis based on the frequencyresponse of a photometer circuit based on operational amplifier (op amp) is carried out. Opamps are universally used in monitoring photodetectors and there are a variety of amplifierconnections for this purpose. However, the electronic circuits that are usually used to carryout the signal treatment in photometer circuits introduce some limitations in theperformance of the photometers that influence the selection of the op amps and otherelectronic devices. For example, the bandwidth, slew-rate, noise, input impedance and gain,among other characteristics of the op amp, are often the performance limiting factors ofphotometer circuits. For this reason, in this paper a comparative analysis between twophotodiode amplifier circuits is carried out. One circuit is based on a conventional currentto-voltage converter connection and the other circuit is based on a robust current-to-voltageconverter connection. The results are satisfactory and show that the photodiode amplifierperformance can be improved by using robust control techniques.

  8. Automatic photometric titration procedure based on multicommutation and flow-batch approaches employing a photometer based on twin LEDs

    OpenAIRE

    Silva,Milton B. da; Crispino,Carla C.; REIS, Boaventura F.

    2010-01-01

    In this work, a reliable and inexpensive photometer based on twin LEDs assembled as a radiation source and as a photodetector is described. The setup including the photometer and flow system module was designed to implement an automated titration procedure employing the multicommuted flow injection analysis (MCFIA) process. The proposed system was able to carry out photometric titration without using analytical curve to achieve the sample concentration. Its usefulness was proven by analyzing ...

  9. NO(2) photometer Based on Solid-State Light Sources.

    Science.gov (United States)

    Fetzer, G J; Miao, L; Chilla, J L; Pikal, J M; Menoni, C S

    1998-08-20

    A sensitive NO(2) analyzer, that uses a commercial LED emitting near 450 nm, has been developed. The prototype can measure NO(2) concentrations as low as 1 part in 10(9) as defined by the Environmental Protection Agency. The response time of the system is 1 min. In addition, a demonstration of the use of external-cavity frequency-doubled diode laser radiation to accomplish similar measurements is reported. However, because of low nonlinear optical conversion efficiencies, comparable detection limits were not possible. Nonetheless, frequency-doubled diode-laser wavelengths have the potential to reach farther into the UV than LED technology, allowing the detection and measurement of numerous other gaseous species of interest.

  10. How hot is the sun

    Institute of Scientific and Technical Information of China (English)

    刘超

    2001-01-01

    Do you know how hot thesun is? There are no solidsor liquids on the sun. Why not? The temperature onoutside the sun is more than 10, 000℃, and that at the centre is about 20, 000, 000℃.The sun is so hot that all thesolids and all the liquids havebeen turned into gases.

  11. The sun, our star

    Science.gov (United States)

    Noyes, R. W.

    Observational data, analytical models, and instrumentation used to study the sun and its evolution are detailed, and attention is given to techniques for converting solar energy to useful power on earth. The star ignited when the mutual gravitational attractions of dust and vapor in a primordial cloud in the Galaxy caused an in-rush of accelerating particles which eventually became dense enough to ignite. The heat grew until inward rushing matter was balanced by outward moving radiative forces. The planets formed from similar debris, and solar radiation is suggested to have triggered the chemical reactions giving rise to life on earth. Visual, spectroscopic, coronagraphic, and UV observations of the sun from the ground and from spacecraft, particularly Skylab, are described, together with features of the solar surface, magnetic field, sunspots, and coronal loops. Models for the processes that occur in the solar interior are explored, as are the causes of solar flares. Attention is given to solar cells, heliostat arrays, wind turbines, and water turbines as means to convert, either directly or indirectly, the earth-bound solar energy to electrical and thermal power. Finally, the life cycle of the sun, about 9 billion yr in duration, is summarized, noting the current status of midlife.

  12. Neptune as a Mirror for the Sun

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    How would the Kepler mission see a star like the Sun? We now know the answer to this question due to a creative approach: a new study has used the Kepler K2 mission to detect signals from the Sun reflected off of the surface of Neptune.Asteroseismology uses different oscillation modes of a star to probe its internal structure and properties. [Tosaka]Information in OscillationsKeplers most glamorous work is in discovering new planets around other stars. To successfully do this, however, the spacecraft is also quietly doing a lot of very useful work in the background, characterizing the many stars in our vicinity that planets might be found around.One of the ways Kepler gets information about these stars is from oscillations of the stars intensities. In asteroseismology, we look at oscillatory modes that are caused by convection-driven pressure changes on the inside of the star. All stars with near-surface convection oscillate like this including the Sun and by measuring the oscillations in intensity of these stars, we can make inferences about the stars properties.A Planetary MirrorWe do this by first understanding our Suns oscillations especially well (made easier by the fact that its nearby!). Then we use asteroseimic scaling relations determined empirically that relate characteristics like mass and radius of other stars to those of the Sun, based on the relation between the stars oscillation properties to the Suns.The trouble is, those oscillation properties are difficult to measure, and different instruments often measure different values. For this reason, wed like to measure the Suns oscillations with the same instrument we use to measure other stars oscillations: Kepler.Top panel: Kepler K2 49-day light curve of Neptune. Bottom panel: power density spectrum as a function of frequency (grey). Neptunes rotation frequencies and harmonics appear toward the left side (blue); the excess power due to the solar modes is visible toward the bottom right. The green curve

  13. Multiyear Aerosol Study Based on Lidar&Sunphotometer Measurements in Romania

    Science.gov (United States)

    Nemuc, Anca; Binietoglou, Ioannis; Andrei, Simona; Dandocsi, Alexandru; Stefanie, Horatiu

    2016-06-01

    This observational study focused on three-years time-averaged data set (January 2012-2015). An investigation of long-term trends was performed on two different data sets derived from active and passive remote sensing measurements in Magurele, Romania. Measurements of sun photometer aerosol optical depth (AOD) at 500 nm and 340 nm show the mean values of 0.230 ±0 .118 and 0.398 ± 0.185, respectively. The lidar AOD at 532 and 355nm has a mean of 0.271 ±.0.164 and 0.472 ± 0.165 respectively. The highest seasonal mean value was measured by the lidar during the summer of 2014 while the lowest seasonal value was measured by the sunphotometer in February 2012. The origin of atmospheric aerosols has been analyzed using both backtajectories of Hysplit and Circulation Type Classification (CTCs) methods.

  14. Technical Note: The single particle soot photometer fails to detect PALAS soot nanoparticles

    Directory of Open Access Journals (Sweden)

    M. Gysel

    2012-07-01

    Full Text Available The single particle soot photometer (SP2 uses laser-induced incandescence (LII for the measurement of atmospheric black carbon (BC particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit (LDL. It is commonly accepted that a particle must contain at least several tenths of femtograms BC in order to be detected by the SP2.

    Here we show the unexpected result that BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM, is clearly above the typical LDL of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST, fullerene soot and carbon black particles (Cabot Regal 400R reveals that particle morphology can affect the SP2's LDL. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely-packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, the PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to vaporisation because of their small size (primary particle diameter ~5–10 nm. It is not surprising that particle morphology can have an effect on the SP2's LDL, however, such a dramatic effect as reported here for PALAS soot was not expected. In conclusion, the SP2's LDL at a certain laser power depends on total BC mass per particle for compact particles with sufficiently high effective density. However, for fractal-like agglomerates of very small primary particles and low fractal dimension, the BC mass per primary particle determines the limit of detection, independent of the total

  15. Technical Note: The single particle soot photometer fails to reliably detect PALAS soot nanoparticles

    Directory of Open Access Journals (Sweden)

    M. Gysel

    2012-12-01

    Full Text Available The single particle soot photometer (SP2 uses laser-induced incandescence (LII for the measurement of atmospheric black carbon (BC particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit. It is commonly accepted that a particle must contain at least several tenths of a femtogram BC in order to be detected by the SP2.

    Here we show the result that most BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM, is clearly above the typical lower detection limit of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST, fullerene soot and carbon black particles (Cabot Regal 400R reveals that particle morphology can affect the SP2's lower detection limit. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, most PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to their vaporisation temperature because of their small size (Dpp ≈ 5–10 nm. Previous knowledge from pulsed laser-induced incandescence indicated that particle morphology might have an effect on the SP2's lower detection limit, however, an increase of the lower detection limit by a factor of ∼5–10, as reported here for PALAS soot, was not expected.

    In conclusion, the SP2's lower detection limit at a certain laser power depends primarily on the total BC mass per particle for compact particles with sufficiently high effective

  16. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from one year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.6%. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8%. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.81%. Therefore, applying this new correction method, both instruments can now be utilized to determine the solar broadband extinction in tower plants sufficiently accurate.

  17. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    Directory of Open Access Journals (Sweden)

    N. Hanrieder

    2015-05-01

    , additional measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from one year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.6%. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8%. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.81%. Therefore, applying this new correction method, both instruments can now be utilized to determine the solar broadband extinction in tower plants sufficiently accurate.

  18. New portable time-resolved photometer for monitoring the calcium dynamics of osteoblasts under mechanical and zero-gravity stimulation

    Science.gov (United States)

    Struckmeier, Jens; Tenbosch, Jochen; Klopp, Erk; Born, Matthias; Hofmann, Martin R.; Jones, David B.

    2000-04-01

    We introduce a compact and portable photometric system for measurements of the calcium dynamics in cells. The photometer is designed for applications in centrifuges or in zero-gravity environment and thus extremely compact and reliable. It operates with the calcium-sensitive dye Indo-1. The excitation wavelength of 345nm is generated by frequency doubling of a laser diode. Two compact photomultiplier tubes detect the fluorescent emission. The electronics provides the sensitivity of photon counting combined with simultaneous measurement of the temperature, of air pressure, and of gravitational force. Internal data storage during the experiment is possible. A newly developed cell chamber stabilizes the cell temperature to 37.0 percent C +/- 0.1 degree C and includes a perfusion system to supply the cells with medium. The system has a modular set-up providing the possibility to change light source and detectors for investigation of other ions than calcium. Quantitative measurements of the intracellular calcium concentration are based on a comprehensive calibration of our system. First experiments show that the calcium dynamics of osteosarcoma cells stimulated by parathyroid hormone is observable.

  19. The filter-loading effect by ambient aerosols in filter absorption photometers depends on the coating of the sampled particles

    Science.gov (United States)

    Drinovec, Luka; Gregorič, Asta; Zotter, Peter; Wolf, Robert; Bruns, Emily Anne; Prévôt, André S. H.; Petit, Jean-Eudes; Favez, Olivier; Sciare, Jean; Arnold, Ian J.; Chakrabarty, Rajan K.; Moosmüller, Hans; Filep, Agnes; Močnik, Griša

    2017-03-01

    Black carbon is a primary aerosol tracer for high-temperature combustion emissions and can be used to characterize the time evolution of its sources. It is correlated with a decrease in public health and contributes to atmospheric warming. Black carbon measurements are usually conducted with absorption filter photometers, which are prone to several artifacts, including the filter-loading effect - a saturation of the instrumental response due to the accumulation of the sample in the filter matrix. In this paper, we investigate the hypothesis that this filter-loading effect depends on the optical properties of particles present in the filter matrix, especially on the black carbon particle coating. We conducted field campaigns in contrasting environments to determine the influence of source characteristics, particle age and coating on the magnitude of the filter-loading effect. High-time-resolution measurements of the filter-loading parameter in filter absorption photometers show daily and seasonal variations of the effect. The variation is most pronounced in the near-infrared region, where the black carbon mass concentration is determined. During winter, the filter-loading parameter value increases with the absorption Ångström exponent. It is suggested that this effect is related to the size of the black carbon particle core as the wood burning (with higher values of the absorption Ångström exponent) produces soot particles with larger diameters. A reduction of the filter-loading effect is correlated with the availability of the coating material. As the coating of ambient aerosols is reduced or removed, the filter-loading parameter increases. Coatings composed of ammonium sulfate and secondary organics seem to be responsible for the variation of the loading effect. The potential source contribution function analysis shows that high values of the filter-loading parameter in the infrared are indicative of local pollution, whereas low values of the filter

  20. Single-Particle Soot Photometer (SP2) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, Arthur [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-02-01

    The SP2 is an instrument that measures, in situ, the time-dependent scattering and incandescence signals produced by individual BC-containing particles as they travel through a continuous-wave laser beam. Any particle traversing the laser beam will scatter light, and the BC component of a BC-containing particle will absorb some of the laser energy until its temperature is raised to the point at which it incandesces (hereafter we adopt the standard terminology of the SP2 community and denote any substance determined by the SP2 to be BC as refractory black carbon (rBC)). The amplitude of the rBC incandescence signal is related to the amount of refractory material contained in the illuminated particle. By binning the individual incandescence signals per unit sample volume, the mass concentration [ng/m3] of rBC can be derived. By binning the individual signals by volume equivalent diameter the size distribution (dN/dlogDVED) per unit time can be derived. The rBC mass loading per unit time and the rBC size distribution unit time are the core data products produced by the SP2. Additionally, the scattering channel can be used to provide information on the rBC particle population-based mixing states within ambient aerosols. However, this data product is produced on a requested-basis since additional detailed analysis and QC/QA must be conducted.

  1. Aerosol Properties over Southeastern China from Multi-Wavelength Raman and Depolarization Lidar Measurements

    Directory of Open Access Journals (Sweden)

    Heese Birgit

    2016-01-01

    Full Text Available A dataset of particle optical properties of highly polluted urban aerosol over the Pearl River Delta, Guangzhou, China is presented. The data were derived from multi-wavelengths Raman and depolarization lidar PollyXT and AERONET sun photometer measurements. The measurement campaign was conducted from Nov 2011 to June 2012. High aerosol optical depth was observed in the polluted atmosphere over this megacity, with a mean value of 0.54 ± 0.33 and a peak value of even 1.9. For the particle characterization the lidar ratio and the linear particle depolarization ratio, both at 532 nm, were used. The mean values of these properties are 48.0 sr ± 10.7 sr for the lidar ratio and 4%+-4% for the particle depolarization ratio, which means most depolarization measurements stayed below 10%. So far, most of these results indicate urban pollution particles mixed with particles arisen from biomass and industrial burning.

  2. Aerosol Properties over Southeastern China from Multi-Wavelength Raman and Depolarization Lidar Measurements

    Science.gov (United States)

    Heese, Birgit; Althausen, Dietrich; Baars, Holger; Bohlmann, Stephanie; Deng, Ruru

    2016-06-01

    A dataset of particle optical properties of highly polluted urban aerosol over the Pearl River Delta, Guangzhou, China is presented. The data were derived from multi-wavelengths Raman and depolarization lidar PollyXT and AERONET sun photometer measurements. The measurement campaign was conducted from Nov 2011 to June 2012. High aerosol optical depth was observed in the polluted atmosphere over this megacity, with a mean value of 0.54 ± 0.33 and a peak value of even 1.9. For the particle characterization the lidar ratio and the linear particle depolarization ratio, both at 532 nm, were used. The mean values of these properties are 48.0 sr ± 10.7 sr for the lidar ratio and 4%+-4% for the particle depolarization ratio, which means most depolarization measurements stayed below 10%. So far, most of these results indicate urban pollution particles mixed with particles arisen from biomass and industrial burning.

  3. Biomass Burning Research Using DOE ARM Single-Particle Soot Photometer (SP2) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Onasch, Timothy B [Aerodyne Research, Inc., Billerica, MA (United States); Sedlacek, Arthur J [Brookhaven National Lab. (BNL), Upton, NY (United States); Lewis, Ernie [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-03-01

    The focus of this laboratory study was to investigate the chemical and optical properties, and the detection efficiencies, of tar balls generated in the laboratory using the same instruments deployed on the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility Gulfstream-1 (G-1) aircraft during the 2013 Biomass Burning Observation Project (BBOP) field study, during which tar balls were observed in wildland biomass burning particulate emissions. Key goals of this laboratory study were: (a) measuring the chemical composition of tar balls to provide insights into the atmospheric processes that form (evaporation/oxidation) and modify them in biomass burning plumes, (b) identifying whether tar balls contain refractory black carbon, (c) determining the collection efficiencies of tar balls impacting on the 600oC heated tungsten vaporizer in the Aerodyne Soot Particle Aerosol Mass Spectrometer (SP-AMS) (i.e., given the observed low volatilities, AMS measurements might underestimate organic biomass burning plume loadings), and (d) measuring the wavelength-dependent, mass-specific absorption cross-sections of brown carbon components of tar balls. This project was funded primarily by the DOE Atmospheric System Research (ASR) program, and the ARM Facility made their single-particle soot photometer (SP2) available for September 1-September 31, 2016 in the Aerodyne laboratories. The ARM mentor (Dr. Sedlacek) requested no funds for mentorship or data reduction. All ARM SP2 data collected as part of this project are archived in the ARM Data Archive in accordance with established protocols. The main objectives of the ARM Biomass Burning Observation Period (BBOP, July-October, 2013) field campaign were to (1) assess the impact of wildland fires in the Pacific Northwest on climate, through near-field and regional intensive measurement campaigns, and (2) investigate agricultural burns to determine how those biomass burn plumes differ from

  4. Radio emission of the sun and planets

    CERN Document Server

    Zheleznyakov, V V

    1970-01-01

    International Series of Monographs in Natural Philosophy, Volume 25: Radio Emission of the Sun and Planets presents the origin of the radio emission of the planets. This book examines the outstanding triumphs achieved by radio astronomy of the solar system. Comprised of 10 chapters, this volume begins with an overview of the physical conditions in the upper layers of the Sun, the Moon, and the planets. This text then examines the three characteristics of radio emission, namely, the frequency spectrum, the polarization, and the angular spectrum. Other chapters consider the measurements of the i

  5. Multi-Aperture CMOS Sun Sensor for Microsatellite Attitude Determination

    Directory of Open Access Journals (Sweden)

    Michele Grassi

    2009-06-01

    Full Text Available This paper describes the high precision digital sun sensor under development at the University of Naples. The sensor determines the sun line orientation in the sensor frame from the measurement of the sun position on the focal plane. It exploits CMOS technology and an original optical head design with multiple apertures. This allows simultaneous multiple acquisitions of the sun as spots on the focal plane. The sensor can be operated either with a fixed or a variable number of sun spots, depending on the required field of view and sun-line measurement precision. Multiple acquisitions are averaged by using techniques which minimize the computational load to extract the sun line orientation with high precision. Accuracy and computational efficiency are also improved thanks to an original design of the calibration function relying on neural networks. Extensive test campaigns are carried out using a laboratory test facility reproducing sun spectrum, apparent size and distance, and variable illumination directions. Test results validate the sensor concept, confirming the precision improvement achievable with multiple apertures, and sensor operation with a variable number of sun spots. Specifically, the sensor provides accuracy and precision in the order of 1 arcmin and 1 arcsec, respectively.

  6. Review - The Sun Rises

    Directory of Open Access Journals (Sweden)

    Mark Bender

    2012-12-01

    Full Text Available Review of: Blackburn, Stuart H. 2010. The Sun Rises: A Shaman's Chant, Ritual Exchange and Fertility in the Apatani Valley. Leiden: Brill. xvii+401. Color and black and white photographs, maps. ISBN: 9789-0041-7578-5 (hardcover, 97USD. The Sun Rises is a model study contextualizing an oral narrative tradition in the social and ritual fabric of a remote community in northeast India. In many ways a companion volume to Himalayan Tribal Tales (Blackburn 2008, the text presents the first substantial translation of a key ritual text of the Apantani Valley dwellers in Arunachal Pradesh, located on the contested border between China (Tibet and India. The Apatani speak a Tibeto-Burman language, practice intensive rice agriculture in carefully terraced fields, and number about 35,000. Their clans populate several centuries-old villages. Until recently, they were separated from the lowlands of Assam and surrounded only by peoples practicing various forms of shifting agriculture. The valley dwellers have increasingly encountered modernization over the last few decades, including Indian and global popular culture, and Christianity. The heart of this book is a chant of nineteen segments.

  7. EZ LIDAR measurement results in the frame of Indian Monsoon TIGER-Z NASA campaign

    Science.gov (United States)

    Lolli, S.; Welton, E. J.; Sauvage, L.

    2008-10-01

    Lidar investigation of temporal and vertical optical atmospheric properties will play a key role in the future for a continuous monitoring over the whole planet through world ground based networks. The EZ LidarTM, manufactured by LEOSPHERE, has been validated in several campaigns as that one in Southern Great Plains (ARM) or at Goddard Space Flight Center (NASA). An EZ LIDARTM with cross-polarization capabilities was deployed in Kanpur, India in the frame of TIGER-Z campaign organized by NASA/AERONET in order to measure aerosol microphysical and optical properties in the Gange basin. In addition, 12 sun-photometers were deployed during this campaign and CALIPSO (The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data were also acquired. In this work we present the results in retrieving aerosol extinction and backscattering from EZ LidarTM measurements, and the validation of the space borne instrument CALIPSO under the satellite track. EZ LidarTM is also coupled with the photometers to provide the measurements of the Aerosol Optical Depth over the selected region.

  8. Automatic determination of insolubles in lubricating oils by flow injection analysis employing an LED-photometer detector.

    Science.gov (United States)

    Pignalosa, Gustavo; Sixto, Alexandra; Knochen, Moisés

    2007-10-31

    A flow injection system is presented for the determination of the insolubles content in used lubricating oil samples. The system is based on the injection of an aliquot of the sample in a stream of organic solvent where it is dispersed, and measurement of the scattered radiation (measured as apparent absorbance) in the visible range (lambda=640nm). An LED-based photometer was used for this purpose. The whole system including sample injection and data acquisition was controlled by a personal computer. Calibration curves exhibited good linearity (h=0.415+/-0.016C+0.00+/-0.03, r(2)=0.9995, confidence level of 95%) in the range up to 2.68% (insolubles in pentane). Detection and quantification limits were respectively 0.07% and 0.16% (w/w). The method was validated by analysis of 25 real samples by the proposed method and the FTIR method finding high correlation. Waste generation and reactive consumption is much less than in the official method (ASTM D-893). The proposed method employs 25mL of kerosene per sample while the official method employs 200mL of pentane.

  9. Eruptions from the Sun

    Science.gov (United States)

    Kohler, Susanna

    2015-11-01

    The Sun often exhibits outbursts, launching material from its surface in powerful releases of energy. Recent analysis of such an outburst captured on video by several Sun-monitoring spacecraft may help us understand the mechanisms that launch these eruptions.Many OutburstsSolar jets are elongated, transient structures that are thought to regularly release magnetic energy from the Sun, contributing to coronal heating and solar wind acceleration. Coronal mass ejections (CMEs), on the other hand, are enormous blob-like explosions, violently ejecting energy and mass from the Sun at incredible speeds.But could these two types of events actually be related? According to a team of scientists at the University of Science and Technology of China, they may well be. The team, led by Jiajia Liu, has analyzed observations of a coronal jet that they believe prompted the launch of a powerful CME.Observing an ExplosionGif of a movie of the CME, taken by the Solar Dynamics Observatorys Atmospheric Imaging Assembly at a wavelength of 304. The original movie can be found in the article. [Liu et al.]An army of spacecraft was on hand to witness the event on 15 Jan 2013 including the Solar Dynamics Observatory (SDO), the Solar and Heliospheric Observatory (SOHO), and the Solar Terrestrial Relations Observatory (STEREO). The instruments on board these observatories captured the drama on the northern limb of the Sun as, at 19:32 UT, a coronal jet formed. Just eight minutes later, a powerful CME was released from the same active region.The fact that the jet and CME occurred in the same place at roughly the same time suggests theyre related. But did the initial motions of the CME blob trigger the jet? Or did the jet trigger the CME?Tying It All TogetherIn a recently published study, Liu and collaborators analyzed the multi-wavelength observations of this event to find the heights and positions of the jet and CME. From this analysis, they determined that the coronal jet triggered the release

  10. Regional and local variations in atmospheric aerosols using ground-based sun photometry during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) in 2012

    Science.gov (United States)

    Sano, Itaru; Mukai, Sonoyo; Nakata, Makiko; Holben, Brent N.

    2016-11-01

    Aerosol mass concentrations are affected by local emissions as well as long-range transboundary (LRT) aerosols. This work investigates regional and local variations of aerosols based on Distributed Regional Aerosol Gridded Observation Networks (DRAGON). We constructed DRAGON-Japan and DRAGON-Osaka in spring of 2012. The former network covers almost all of Japan in order to obtain aerosol information in regional scale over Japanese islands. It was determined from the DRAGON-Japan campaign that the values of aerosol optical thickness (AOT) decrease from west to east during an aerosol episode. In fact, the highest AOT was recorded at Fukue Island at the western end of the network, and the value was much higher than that of urban areas. The latter network (DRAGON-Osaka) was set as a dense instrument network in the megalopolis of Osaka, with a population of 12 million, to better understand local aerosol dynamics in urban areas. AOT was further measured with a mobile sun photometer attached to a car. This transect information showed that aerosol concentrations rapidly changed in time and space together when most of the Osaka area was covered with moderate LRT aerosols. The combined use of the dense instrument network (DRAGON-Osaka) and high-frequency measurements provides the motion of aerosol advection, which coincides with the wind vector around the layer between 700 and 850 hPa as provided by the reanalysis data of the National Centers for Environmental Prediction (NCEP).

  11. The Sun, Mercury, and Venus

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

    The Messenger mission to Mercury opened a new window into the inner solar system. In 2008, this mission began a number of years of flybys, culminating in an orbital insertion around Mercury and producing unparalleled observations about this mysterious innermost planet. Mercury orbits so close to the Sun, from the point of view of Earth, that seeing it from the Earth against the Sun's glare is a great challenge. At the same time, the huge gravitational force of the Sun makes it a challenge to put a mission on Mercury without losing it into the Sun. Now, with heightened understanding of Mercury,

  12. Occupational sun protection: workplace culture, equipment provision and outdoor workers' characteristics.

    Science.gov (United States)

    Reeder, Anthony I; Gray, Andrew; McCool, Judith P

    2013-01-01

    The aim of this study was to describe outdoor workers' sun-protective practices, workplace sun-safety culture and sun-protective equipment provision; investigate the association of demographic, personal and occupational factors with sun-protective practices; and identify potential strategies for improving workers' sun protection. The present study used a clustered survey design with randomly identified employers in nine occupations. Employees provided questionnaire measures of demographics, personal characteristics (skin type, skin cancer risk perceptions, tanning attitudes, sun-exposure knowledge), personal occupational sun protection practices (exposure reduction, use of sun-protective clothing, sunscreen and shade), workplace sun-protective equipment provision and perceived workplace sun-safety culture. Summative scores were calculated for attitudes, knowledge, workplace provision and culture. A multivariable model was built with worker and workplace variables as plausible predictors of personal sun protection. In this study, 1,061 workers (69% participation) from 112 workplaces provided sufficient information for analysis. Sex, age, prioritized ethnicity, education and risk perception differed significantly between occupational groups (pworkplace sun-protection equipment provision and supportive culture. After adjustment, each one-point increase in Workplace Sun-safety Culture 2013Score (range 12 points) was associated with a 0.16 higher Personal Sun-Protection Score (pWorkplace Provision Score (range 4 points) was associated with a 0.14 higher score (pworkplace culture are promising components for the development of comprehensive programmes to improve outdoor workers' sun-protective practices.

  13. The Rapidly Rotating Sun

    Science.gov (United States)

    Hanasoge, Shravan M.; Duvall, Thomas L., Jr.; Sreenivasan, Katepalli R.

    2012-01-01

    Convection in the solar interior is thought to comprise structures at a continuum of scales, from large to small. This conclusion emerges from phenomenological studies and numerical simulations though neither covers the proper range of dynamical parameters of solar convection. In the present work, imaging techniques of time-distance helioseismology applied to observational data reveal no long-range order in the convective motion. We conservatively bound the associated velocity magnitudes, as a function of depth and the spherical-harmonic degree l to be 20-100 times weaker than prevailing estimates within the wavenumber band l ux of a solar luminosity outwards? The Sun is seemingly a much faster rotator than previously thought, with advection dominated by Coriolis forces at scales l < 60.

  14. Sun light European Project

    Science.gov (United States)

    Soubielle, Marie-Laure

    2015-04-01

    2015 has been declared the year of light. Sunlight plays a major role in the world. From the sunbeams that heat our planet and feed our plants to the optical analysis of the sun or the modern use of sun particles in technologies, sunlight is everywhere and it is vital. This project aims to understand better the light of the Sun in a variety of fields. The experiments are carried out by students aged 15 to 20 in order to share their discoveries with Italian students from primary and secondary schools. The experiments will also be presented to a group of Danish students visiting our school in January. All experiments are carried out in English and involve teams of teachers. This project is 3 folds: part 1: Biological project = what are the mechanisms of photosynthesis? part 2: Optical project= what are the components of sunlight and how to use it? part 3: Technical project= how to use the energy of sunlight for modern devices? Photosynthesis project Biology and English Context:Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can later fuel the organisms' activities. This chemical energy is stored in molecules which are synthesized from carbon dioxide and water. In most cases, oxygen is released as a waste product. Most plants perform photosynthesis. Photosynthesis maintains atmospheric oxygen levels and supplies all of the organic compounds and most of the energy necessary for life on Earth. Outcome: Our project consists in understanding the various steps of photosynthesis. Students will shoot a DVD of the experiments presenting the equipments required, the steps of the experiments and the results they have obtained for a better understanding of photosynthesis Digital pen project Electricity, Optics and English Context: Sunlight is a complex source of light based on white light that can be decomposed to explain light radiations or colours. This light is a precious source to create

  15. Physics of the sun

    CERN Document Server

    Holzer, Thomas; Mihalas, Dimitri; Ulrich, Roger

    1986-01-01

    This volume, together with its two companion volumes, originated in a study commis­ sioned by the United States National Academy of Sciences on behalf of the National Aeronautics and Space Administration. A committee composed of Tom Holzer, Dimitri Mihalas, Roger Ulrich and myself was asked to prepare a comprehensive review of current knowledge concerning the physics of the sun. We were fortunate in being able to persuade many distinguished scientists to gather their forces for the preparation of 21 separate chapters covering not only solar physics but also relevant areas of astrophysics and solar-terrestrial relations. It proved necessary to divide the chapters into three separate volumes that cover three different aspects of solar physics. Volumes 1 and 2 are concerned with 'The Solar Interior' and with 'The Solar Atmosphere'. This volume, devoted to 'Astrophysics and Solar-Terrestrial Relations', focuses on problems of solar physics from these two different but complementary perspectives. The emphasis thr...

  16. Why the sun sucks - Architects versus the sun

    NARCIS (Netherlands)

    De Lange, N.; Niesten, J.; Taminiau, P.

    2014-01-01

    This "designers' manual" is made during the TIDO-course AR0531 Innovation and Sustainability This manual will show how not to design with the Sun. By showing examples how buildings have failed that have not taken the Sun and its effects in consideration, one should get a clearer picture of how you

  17. Why the sun sucks - Architects versus the sun

    NARCIS (Netherlands)

    De Lange, N.; Niesten, J.; Taminiau, P.

    2014-01-01

    This "designers' manual" is made during the TIDO-course AR0531 Innovation and Sustainability This manual will show how not to design with the Sun. By showing examples how buildings have failed that have not taken the Sun and its effects in consideration, one should get a clearer picture of how you

  18. Sensitivity of the Single Particle Soot Photometer to different black carbon types

    Directory of Open Access Journals (Sweden)

    M. Laborde

    2012-01-01

    Full Text Available Black carbon (BC is nowadays mainly of anthropogenic origin. It is the dominant light absorbing component of atmospheric aerosols, playing an important role in the earth's radiative balance and therefore relevant to climate change studies. In addition, BC is known to be harmful to humans making it relevant to policy makers. Nevertheless, the measurement of BC remains biased by the instrument-based definition of BC. The Single Particle Soot Photometer (SP2, allows the measurement of the refractory BC (rBC mass of individual particle using laser-induced incandescence. However the SP2 needs an empirical calibration to retrieve the rBC mass from the incandescence signal and the sensitivity of the SP2 differs between different BC types. Ideally, for atmospheric studies, the SP2 should be calibrated using ambient particles containing a known mass of ambient rBC. However, such "ambient BC" calibration particles cannot easily be obtained and thus commercially available BC particles are commonly used for SP2 calibration instead. In this study we tested the sensitivity of the SP2 to different BC types in order to characterize the potential error introduced by using non-ambient BC for calibration. The sensitivity of the SP2 was determined for rBC from thermodenuded diesel exhaust, wood burning exhaust and ambient particles as well as for commercially available products: Aquadag® and fullerene soot.

    Thermodenuded, fresh diesel exhaust has been found to be ideal for SP2 calibration for two reasons. First, the small amount of non-BC matter upon emission reduces the risk of bias due to incomplete removal of non-BC matter and second, it is considered to represent atmospheric rBC as diesel exhaust is the main source of BC in most locations. The SP2 was found to be up to 16% less sensitive to rBC from thermodenuded ambient particles (≤15 fg than rBC from diesel exhaust, however, at least part of this difference can be explained by

  19. Sensitivity of the Single Particle Soot Photometer to different black carbon types

    Directory of Open Access Journals (Sweden)

    M. Laborde

    2012-05-01

    Full Text Available Black carbon (BC is now mainly of anthropogenic origin. It is the dominant light absorbing component of atmospheric aerosols, playing an important role in the earth's radiative balance and therefore relevant to climate change studies. In addition, BC is known to be harmful to human beings making it relevant to policy makers. Nevertheless, the measurement of BC remains biased by the instrument-based definition of BC. The Single Particle Soot Photometer (SP2, allows the measurement of the refractory BC (rBC mass of individual particles using laser-induced incandescence. However, the SP2 needs an empirical calibration to retrieve the rBC mass from the incandescence signal and the sensitivity of the SP2 differs between different BC types. Ideally, for atmospheric studies, the SP2 should be calibrated using ambient particles containing a known mass of ambient rBC. However, such "ambient BC" calibration particles cannot easily be obtained and thus commercially available BC particles are commonly used for SP2 calibration instead. In this study we tested the sensitivity of the SP2 to different BC types in order to characterize the potential error introduced by using non-ambient BC for calibration. The sensitivity of the SP2 was determined, using an aerosol particle mass analyzer, for rBC from thermodenuded diesel exhaust, wood burning exhaust and ambient particles as well as for commercially available products: Aquadag® and fullerene soot.

    Thermodenuded, fresh diesel exhaust has been found to be ideal for SP2 calibration for two reasons. First, the small amount of non-BC matter upon emission reduces the risk of bias due to incomplete removal of non-BC matter and second, it is considered to represent atmospheric rBC in urban locations where diesel exhaust is the main source of BC. The SP2 was found to be up to 16% less sensitive to rBC from thermodenuded ambient particles (≤15 fg than rBC from diesel exhaust, however, at least part

  20. Isotopes Tell Sun's Origin and Operation

    Science.gov (United States)

    Manuel, O.; Kamat, Sumeet A.; Mozina, Michael

    2006-03-01

    Modern versions of Aston's mass spectrometer enable measurements of two quantities - isotope abundances and masses - that tell the Sun's origin and operation. Isotope analyses of meteorites, the Earth, Moon, Mars, Jupiter, the solar wind, and solar flares over the past 45 years indicate that fresh, poorly-mixed, supernova debris formed the solar system. The iron-rich Sun formed on the collapsed supernova core and now itself acts as a magnetic plasma diffuser, as did the precursor star, separating ions by mass. This process covers the solar surface with lightweight elements and with the lighter isotopes of each element. Running difference imaging provides supporting evidence of a rigid, iron-rich structure below the Sun's fluid outer layer of lightweight elements. Mass measurements of all 2,850 known nuclides expose repulsive interactions between neutrons that trigger neutron-emission at the solar core, followed by neutron-decay and a series of reactions that collectively generate solar luminosity, solar neutrinos, the carrier gas for solar mass separation, and an outpouring of solar-wind hydrogen from the solar surface. Neutron-emission and neutron-decay generate ~ 65% of solar luminosity; H-fusion ~ 35%, and ~ 1% of the neutron-decay product survives to depart as solar-wind hydrogen. The energy source for the Sun and other ordinary stars seems to be neutron-emission and neutron-decay, with partial fusion of the decay product, rather than simple fusion of hydrogen into helium or heavier elements.

  1. Balloon-Borne System Would Aim Instrument Toward Sun

    Science.gov (United States)

    Polites, M. E.

    1992-01-01

    Proposed system including digital control computer, control sensors, and control actuators aims telescope or other balloon-borne instrument toward Sun. Pointing system and instrument flown on gondola, suspended from balloon. System includes reaction wheel, which applies azimuthal control torques to gondola, and torque motor to apply low-frequency azimuthal torques between gondola and cable. Three single-axis rate gyroscopes measure yaw, pitch, and roll. Inclinometer measures roll angle. Two-axis Sun sensor measures deviation, in yaw and pitch, of attitude of instrument from line to apparent center of Sun. System provides initial coarse pointing, then maintains fine pointing.

  2. Ra: The Sun for Science and Humanity

    Science.gov (United States)

    1996-01-01

    To guide the development of the Ra Strategic Framework, we defined scientific and applications objectives. For our primary areas of scientific interest, we choose the corona, the solar wind, the Sun's effect on the Earth, and solar theory and model development. For secondary areas of scientific interest, we selected sunspots, the solar constant, the Sun's gravitational field, helioseismology and the galactic cosmic rays. We stress the importance of stereoscopic imaging, observations at high spatial, spectral, and temporal resolutions, as well as of long duration measurements. Further exploration of the Sun's polar regions is also important, as shown already by the Ulysses mission. From an applications perspective, we adopted three broad objectives that would derive complementary inputs for the Strategic Framework. These were to identify and investigate: possible application spin-offs from science missions, possible solar-terrestrial missions dedicated to a particular application, and possible future applications that require technology development. The Sun can be viewed as both a source of resources and of threats. Our principal applications focus was that of threat mitigation, by examining ways to improve solar threat monitoring and early warning systems. We compared these objectives to the mission objectives of past, current, and planned international solar missions. Past missions (1962-1980) seem to have been focused on improvement of scientific knowledge, using multiple instrument spacecraft. A ten year gap followed this period, during which the results from previous missions were analyzed and solar study programmes were prepared in international organizations. Current missions (1990-1996) focus on particular topics such as the corona, solar flares, and coronal mass ejections. In planned missions, Sun/Earth interactions and environmental effects of solar activity are becoming more important. The corona is the centre of interest of almost all planned missions

  3. Smart, passive sun facing surfaces

    Science.gov (United States)

    Hively, Lee M.

    1996-01-01

    An article adapted for selectively utilizing solar radiation comprises an absorptive surface and a reflective surface, the absorptive surface and the reflective surface oriented to absorb solar radiation when the sun is in a relatively low position, and to reflect solar radiation when the sun is in a relatively high position.

  4. Global Seismology of the Sun

    CERN Document Server

    Basu, Sarbani

    2016-01-01

    The seismic study of the Sun and other stars offers a unique window into the interior of these stars. Thanks to helioseismology, we know the structure of the Sun to admirable precision. In fact, our knowledge is good enough to use the Sun as a laboratory. We have also been able to study the dynamics of the Sun in great detail. Helioseismic data also allow us to probe the changes that take place in the Sun as solar activity waxes and wanes. The seismic study of stars other than the Sun is a fairly new endeavour, but we are making great strides in this field. In this review I discuss some of the techniques used in helioseismic analyses and the results obtained using those techniques. In this review I focus on results obtained with global helioseismology, i.e., the study of the Sun using its normal modes of oscillation. I also briefly touch upon asteroseismology, the seismic study of stars other than the Sun, and discuss how seismic data of others stars are interpreted.

  5. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Directory of Open Access Journals (Sweden)

    N. Hanrieder

    2015-08-01

    , additional measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from 1-year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.57 %. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8 %. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.8 %. Additionally, a simulation approach which just uses sun photometer and common meteorological data to determine the on-site atmospheric extinction at surface is presented and corrected FS11 and LPV4 measurements are validated with the simulation results. For T1 km equal to 0.9 and a 10 min time resolution, an uncertainty analysis showed that an absolute uncertainty of about 0.038 is expected for the FS11 and about 0.057 for the LPV4. Combining both uncertainties results in an overall absolute uncertainty of 0.068 which justifies quite well the mean RMSE between both corrected data sets. For yearly averages several error influences average out and absolute uncertainties of 0.020 and 0.054 can be expected for the FS11 and the LPV4, respectively. Therefore, applying this new correction method, both instruments can now be utilized to sufficiently accurately determine the solar broadband extinction in tower plants.

  6. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from 1-year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.57 %. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8 %. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.8 %. Additionally, a simulation approach which just uses sun photometer and common meteorological data to determine the on-site atmospheric extinction at surface is presented and corrected FS11 and LPV4 measurements are validated with the simulation results. For T1 km equal to 0.9 and a 10 min time resolution, an uncertainty analysis showed that an absolute uncertainty of about 0.038 is expected for the FS11 and about 0.057 for the LPV4. Combining both uncertainties results in an overall absolute uncertainty of 0.068 which justifies quite well the mean RMSE between both corrected data sets. For yearly averages several error influences average out and absolute uncertainties of 0.020 and 0.054 can be expected for the FS11 and the LPV4, respectively. Therefore, applying this new correction method, both instruments can now be utilized to sufficiently accurately determine the solar broadband extinction in tower plants.

  7. Reconnection on the Sun

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    Because the Sun is so close, it makes an excellent laboratory to study processes we cant examinein distant stars. One openquestion is that of how solar magnetic fields rearrange themselves, producing the tremendous releases of energy we observe as solar flares and coronal mass ejections (CMEs).What is Magnetic Reconnection?Magnetic reconnection occurs when a magnetic field rearranges itself to move to a lower-energy state. As field lines of opposite polarity reconnect, magnetic energy is suddenly converted into thermal and kinetic energy.This processis believed to be behind the sudden releases of energy from the solar surface in the form of solar flares and CMEs. But there are many different models for how magnetic reconnection could occur in the magnetic field at the Suns surface, and we arent sure which one of these reconnection types is responsible for the events we see.Recently, however, several studies have been published presenting some of the first observational support of specific reconnection models. Taken together, these observations suggest that there are likely several different types of reconnection happening on the solar surface. Heres a closer look at two of these recent publications:A pre-eruption SDO image of a flaring region (b) looks remarkably similar to a 3D cartoon for typical breakout configuration (a). Click for a closer look! [Adapted from Chen et al. 2016]Study 1:Magnetic BreakoutLed by Yao Chen (Shandong University in China), a team of scientists has presented observations made by the Solar Dynamics Observatory (SDO) of a flare and CME event that appears to have been caused by magnetic breakout.In the magnetic breakout model, a series of loops in the Suns lower corona are confined by a surrounding larger loop structure called an arcade higher in the corona. As the lower loops push upward, reconnection occurs in the upper corona, removing the overlying, confining arcade. Without that extra confinement, the lower coronal loops expand upward

  8. Description of the Sun as a Star: General Physical Characteristics

    Science.gov (United States)

    Kucera, Theresa; Crannell, Carol Jo

    2000-01-01

    Numerical parameters characterizing the size and energy output of the sun are presented. These values are the standard yardstick by which other stars are measured. The large number of significant digits tabulated here serve mainly to illustrate the precision to which these parameters are known. Also listed are parameters characterizing the earth's orbit around the sun and the intensity of the sun's radiation at the mean orbital distance. The appearance of the sun depends critically on how it is observed. Each type of radiation observed carries specific information about the physical processes at work on the sun. Special types of instruments reveal aspects otherwise invisible. Coronagraphs reveal the dimmer outer regions of the sun's atmosphere otherwise visible only during total solar eclipses. Spectroscopy can reveal motions, magnetic field strengths, temperatures and densities. In situ measurements have revealed the characteristics of the solar wind and extended our knowledge of the solar magnetic field both near the earth and beyond the orbits of the planets. As an example, the sun's disk observed almost simultaneously in six different wavelengths of light is shown. In visible light we can see the white disk of the sun with the dark spots known as sunspots. By analyzing the spectral lines produced by the sun we can measure the strength of the sun's magnetic field at its surface, producing a magnetogram. This magnetogram reveals that the sunspots are regions of intense magnetic field. Further images of the sun reveal that the sunspot regions are just the bases of systems of hot loops which emit radio-waves, ultraviolet light and X-rays. The sun imaged in a spectral line of hydrogen known as "H alpha" is shown. In this line we also see the long dark "filaments". These filaments form in long channels between areas of opposing magnetic field. Such channels can be seen in the ultraviolet image. Data concerning the sun are obtained with many different kinds of

  9. Implementation of a Low-Cost Automated LED Photometer for Enzymatic Reaction Detection to Teach Basic Bioelectronics Technologies in Vocational High Schools

    Science.gov (United States)

    Chen, Huai-Yi; Nieh, Hwa-Ming; Yang, Ming-Feng; Chou, Yu-Kung; Chung, Jui-Hsu; Liou, Je-Wen

    2016-01-01

    This study proposes a home-assembled, low-cost blue light-emitting diode (LED) photometer that uses simple and low-cost hardware and software, costing about US $150. This 425-nm wavelength photometer is controlled by an 89C51 microcontroller chip. Glucose concentration detection experiments involving enzyme coupling reactions were carried out to…

  10. Spectral Discrimination of Fine and Coarse Mode Aerosol Optical Depth from AERONET Direct Sun Data of Singapore and South-East Asia

    Science.gov (United States)

    Salinas Cortijo, S.; Chew, B.; Liew, S.

    2009-12-01

    Aerosol optical depth combined with the Angstrom exponent and its derivative, are often used as a qualitative indicator of aerosol particle size, with Angstrom exp. values greater than 2 indicating small (fine mode) particles associated with urban pollution and bio-mass burning. Around this region, forest fires are a regular occurrence during the dry season, specially near the large land masses of Sumatra and Borneo. The practice of clearing land by burning the primary and sometimes secondary forest, results in a smog-like haze covering large areas of regional cities such as cities Singapore, Kuala Lumpur and sometimes the south of Thailand, often reducing visibility and increasing health problems for the local population. In Singapore, the sources of aerosols are mostly from fossil fuel burning (energy stations, incinerators, urban transport etc.) and from the industrial and urban areas. The proximity to the sea adds a possible oceanic source. However, as stated above and depending on the time of the year, there can be a strong bio-mass component coming from forest fires from various regions of the neighboring countries. Bio-mass related aerosol particles are typically characterized by showing a large optical depth and small, sub-micron particle size distributions. In this work, we analyze three years of direct Sun measurements performed with a multi-channel Cimel Sun-Photometer (part of the AERONET network) located at our site. In order to identify bio-mass burning events in this region, we perform a spectral discrimination between coarse and fine mode optical depth; subsequently, the fine mode parameters such as optical depth, optical ratio and fine mode Angstrom exponents (and its derivative) are used to identify possible bio-mass related events within the data set.

  11. Totality eclipses of the Sun

    CERN Document Server

    Littmann, Mark; Willcox, Ken

    2008-01-01

    A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. - ;A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. Totality: Eclipses of the Sun is the best guide and reference book on solar eclipses ever written. It explains: how to observe them; how to photograph and videotape them; why they occur; their history and mythology; and future eclipses - when and where to see them. Totality also tells the remarkable story of how eclipses shocked scientists, revealed the workings of the Sun, and made Einstein famous. And the book shares the experiences and advice of many veteran eclipse observers. Totality: Eclipses of the Sun is profusely ill...

  12. Science Experimenter: Observing the Sun and Solar Eclipses.

    Science.gov (United States)

    Mims, Forrest M., III

    1991-01-01

    Describes the construction and use of simple optical aids that allow the amateur scientist to safely observe sunspots and solar eclipses and also to measure the sun's rotation. (five references) (JJK)

  13. Variation of Fractional Electron Density Fluctuations Near 0.1 AU From the Sun Observed by Ulysses Dual-Frequency Ranging Measurements

    Science.gov (United States)

    Woo, R.; Armstrong, J. W.; Bird, M. K.; Patzold, M.

    1994-01-01

    This paper presents the results of determining fractional density fluctuations, which requires the measurement of absolute electron density as provided by dual-frequency observations of time delay or ranging conducted by the Ulysses Solar Corona Experiment.

  14. Sun, UV Radiation and Your Eyes

    Science.gov (United States)

    ... Patient Stories Español Eye Health / Tips & Prevention Your Eyes and the Sun Sections The Sun, UV Radiation ... Safety Infographic The Sun, UV Radiation and Your Eyes Written by: David Turbert Aug. 28, 2014 Keep ...

  15. Comparison of columnar water vapor over northern China derived from ground-based measurements and MODIS

    Science.gov (United States)

    Liu, Chaoshun; Shi, Runhe; Gao, Wei; Bai, Kaixu

    2011-09-01

    Water vapor represents a small but environmentally significant constituent of the atmosphere. This study retrieved columnar water vapor (CWV) with the 939.3 nm band of a Multi-filter Rotating Shadowband Radiometer (MFRSR) using the modified Langley technique from September 23, 2004 to June 20, 2005 at the XiangHe site.To improve the credibility, the MFRSR results were compared with those obtained from the AERONET (AErosol RObotic NETwork) CIMEL sun-photometer measurements, co-located at the XiangHe site, and the Moderate Resolution Imaging Spectroradiometer (MODIS) Near-Infrared Total Precipitable Water Product (MOD05), respectively. These comparisons show a good agreement in terms of correlation coefficients, slopes, and offsets, revealing that the accuracy of CWV estimation using the MFRSR instrument is reliable and suitable for extended studies in northern China.

  16. Carl Friedrich Richard Foerster (1825-1902) - the inventor of perimeter and photometer.

    Science.gov (United States)

    Grzybowski, Andrzej; Sobolewska, Bianka

    2015-09-01

    Carl Friedrich Richard Foerster (1825-1902) was a German who was born in the Polish city Leszno. He studied medicine at the Medical Faculty of Breslau (now Wroclaw, Poland) University, and later in Heidelberg and Berlin. From 1855, he worked in Breslau, where he established in 1857 the first ophthalmology clinic. Later, he became a professor in ophthalmology, the first director of the Department of Ophthalmology at the University of Breslau, and even the rector of this University. Forster did many pioneering works on visual fields, invented a photometer and the first perimeter, known for many years as the Foerster perimeter. Moreover, he studied night blindness, visual field changes due to different pathologies, and many eye diseases, including glaucoma, cataract, retinal and choroidal diseases.

  17. Inter-comparison of stratospheric O3 and NO2 abundances retrieved from balloon borne direct sun observations and Envisat/SCIAMACHY limb measurements

    Directory of Open Access Journals (Sweden)

    A. Butz

    2006-01-01

    Full Text Available Stratospheric O3 and NO2 abundances measured by different remote sensing instruments are inter-compared: (1 Line-of-sight absorptions and vertical profiles inferred from solar spectra in the ultra-violet (UV, visible and infrared (IR wavelength ranges measured by the LPMA/DOAS (Limb Profile Monitor of the Atmosphere/Differential Optical Absorption Spectroscopy balloon payload during balloon ascent/descent and solar occultation are examined with respect to internal consistency. (2 The balloon borne stratospheric profiles of O3 and NO2 are compared to collocated space-borne skylight limb observations of the Envisat/SCIAMACHY satellite instrument. The trace gas profiles are retrieved from SCIAMACHY spectra using different algorithms developed at the Universities of Bremen and Heidelberg and at the Harvard-Smithsonian Center for Astrophysics. A comparison scheme is used that accounts for the spatial and temporal mismatch as well as differing photochemical conditions between the balloon and satellite borne measurements. It is found that the balloon borne measurements internally agree to within ±10% and ±20% for O3 and NO2, respectively, whereas the agreement with the satellite is ±20% for both gases in the 20 km to 30 km altitude range and in general worse below 20 km.

  18. The Hetu'u Global Network: Measuring the Distance to the Sun Using the June 5th/6th Transit of Venus

    Science.gov (United States)

    Faherty, Jacqueline K.; Rodriguez, David R.; Miller, Scott T.

    2012-01-01

    In the spirit of historic astronomical endeavors, we invited school groups across the globe to collaborate in a solar distance measurement using the rare June 5/6th transit of Venus. In total, we recruited 19 school groups spread over 6 continents and 10 countries to participate in our Hetu'u Global Network. Applying the methods of French…

  19. Anisotropic microstructure near the sun

    Science.gov (United States)

    Coles, W. A.; Grall, R. R.; Spangler, S. R.; Sakurai, T.; Harmon, J. K.

    1996-07-01

    Radio scattering observations provide a means of measuring a two-dimensional projection of the three-dimensional spatial spectrum of electron density, i.e., in the plane perpendicular to the line of sight. Earlier observations have shown that the microstructure at scales of the order of 10 km becomes highly field-aligned inside of 10 Rsolar [Armstrong et al., 1990]. Earlier work has also shown that density fluctuations at scales larger than 1000 km have a Kolmogorov spectrum, whereas the smaller scale structure has a flatter spectrum and is considerably enhanced above the Kolmogorov ``background'' [Coles et al., 1991]. Here we present new observations made during 1990 and 1992. These confirm the earlier work, which was restricted to one source on a few days, but they suggest that the anisotropy changes abruptly near 6 Rsolar which was not clear in the earlier data. The axial ratio measurements are shown on Figure 1 below. The new observations were made with a more uniform sampling of the spatial plane. They show that contours of constant correlation are elliptical. This is apparently inconsistent with the spatial correlation of the ISEE-3 magnetic field which shows a ``Maltese Cross'' shape [Matthaeus et al., 1990]. However this inconsistency may be only apparent: the magnetic field and density correlations need not have the same shape; the scale of the magnetic field correlations is at least 4 orders of magnitude larger; they are much further from the sun; and they are point measurements whereas ours are path-integrated. We also made two simultaneous measurements, at 10 Rsolar, of the anisotropy on scales of 200 to 4000 km. Significant anisotropy was seen on the smaller scales, but the larger scale structure was essentially isotropic. This suggests that the process responsible for the anisotropic microstructure is independent of the larger scale isotropic turbulence. It is then tempting to speculate that the damping of this anisotropic process inside of 6 Rsolar

  20. Prototype of sun projector device

    Science.gov (United States)

    Ihsan; Dermawan, B.

    2016-11-01

    One way to introduce astronomy to public, including students, can be handled by solar observation. The widely held device for this purpose is coelostat and heliostat. Besides using filter attached to a device such as telescope, it is safest to use indirect way for observing the Sun. The main principle of the indirect way is deflecting the sun light and projecting image of the sun on a screen. We design and build a simple and low-cost astronomical device, serving as a supplement to increase public service, especially for solar observation. Without using any digital and intricate supporting equipment, people can watch and relish image of the Sun in comfortable condition, i.e. in a sheltered or shady place. Here we describe a design and features of our prototype of the device, which still, of course, has some limitations. In the future, this prototype can be improved for more efficient and useful applications.

  1. The measurement of constitutive and facultative skin pigmentation and estimation of sun exposure in Caucasians with basal cell carcinoma and cutaneous malignant melanoma

    DEFF Research Database (Denmark)

    Lock-Andersen, J; Drzewiecki, K T; Wulf, H C

    1998-01-01

    In two identical and simultaneously performed case-control studies of basal cell carcinoma (BCC) and cutaneous malignant melanoma (CMM) with age-matched, sex-matched and residence-matched controls, skin pigmentation was measured objectively by skin reflectance spectroscopy in 145 BCC patients...... by all subjects. There were no statistically significant differences in constitutive skin pigmentation at the buttocks between BCC patients and controls (P = 0.96) or between CMM patients and controls (P = 0.13). Facultative skin pigmentation in ultraviolet-exposed sites was not significantly different...

  2. Black carbon aerosol characterization in a coastal city in South China using a single particle soot photometer

    Science.gov (United States)

    Huang, Xiao-Feng; Sun, Tian-Le; Zeng, Li-Wu; Yu, Guang-He; Luan, Sheng-Ji

    2012-05-01

    Black carbon (BC) is the dominant light-absorbing aerosol component in the atmosphere and plays an important role in atmospheric pollution and climate change. The light-absorbing properties of BC rely on particle size, shape, composition, as well as the BC mixing state with other aerosol components, thus more thorough exploration of BC aerosol characteristics is critical in understanding its atmospheric sources and effects. In this study, a newly-developed Single Particle Soot Photometer (SP2) was deployed in Shenzhen, China, for continuous BC measurements to obtain the important information about size distribution and mixing state of BC under severe air pollution conditions of China. The mean BC mass concentrations were found to be 6.0 and 4.1 μg m-3 at an urban site (UT) in the fall and winter, respectively, while it is much lower (2.6 μg m-3) at a rural site (BG) in the fall. The mass size distributions of BC in volume equivalent diameter (VED) at the three sites showed a similar lognormal pattern, with the peak diameter at BG (222 nm) slightly larger than at the UT (210 nm) site. As to mixing state, the average percentage of internally mixed BC at the UT site was detected to be 40% and 46% in the fall and winter, respectively, while that at the BG site in the fall was only a slightly higher (47%), which implies that fresh local fossil fuel combustions were still significant at this rural site. The analysis of extremely high BC concentrations (>20 μg m-3) at UT indicates that they were a complex of comparable contributions from both local fresh emissions and regional transport under unfavorable meteorology. Other characteristics of BC aerosol and their influencing factors in Shenzhen were also discussed.

  3. Autonomous Sun-Direction Estimation Using Partially Underdetermined Coarse Sun Sensor Configurations

    Science.gov (United States)

    O'Keefe, Stephen A.

    In recent years there has been a significant increase in interest in smaller satellites as lower cost alternatives to traditional satellites, particularly with the rise in popularity of the CubeSat. Due to stringent mass, size, and often budget constraints, these small satellites rely on making the most of inexpensive hardware components and sensors, such as coarse sun sensors (CSS) and magnetometers. More expensive high-accuracy sun sensors often combine multiple measurements, and use specialized electronics, to deterministically solve for the direction of the Sun. Alternatively, cosine-type CSS output a voltage relative to the input light and are attractive due to their very low cost, simplicity to manufacture, small size, and minimal power consumption. This research investigates using coarse sun sensors for performing robust attitude estimation in order to point a spacecraft at the Sun after deployment from a launch vehicle, or following a system fault. As an alternative to using a large number of sensors, this thesis explores sun-direction estimation techniques with low computational costs that function well with underdetermined sets of CSS. Single-point estimators are coupled with simultaneous nonlinear control to achieve sun-pointing within a small percentage of a single orbit despite the partially underdetermined nature of the sensor suite. Leveraging an extensive analysis of the sensor models involved, sequential filtering techniques are shown to be capable of estimating the sun-direction to within a few degrees, with no a priori attitude information and using only CSS, despite the significant noise and biases present in the system. Detailed numerical simulations are used to compare and contrast the performance of the five different estimation techniques, with and without rate gyro measurements, their sensitivity to rate gyro accuracy, and their computation time. One of the key concerns with reducing the number of CSS is sensor degradation and failure. In

  4. A new perspective on quiet Sun magnetism

    Institute of Scientific and Technical Information of China (English)

    LITES; Bruce; William

    2009-01-01

    The Hinode mission has provided us with a new, quantitative view of the magnetism of the quiet Sun. It has revealed that the quiet internetwork areas are blanketed by horizontal fields that appear at first sight to have more flux than the vertical fields resolved on the same 0.3 size scale. These measurements point to the possibility that the horizontal fields might be the primary source of the "hidden turbulent flux" of the quiet Sun anticipated from Hanle effect depolarization. In this paper, evidence is presented suggesting that the "seething" horizontal fields observed by Harvey in 2007 and the horizontal fields revealed by Hinode are the same phenomenon. Because the seething fields appear to be of uniform fluctuation over the whole disk, the phenomenon is most likely not associated with the dynamo source of solar activity. Thus, the small-scale "hidden turbulent flux" lends support to the notion of a local solar dynamo acting on granular sizes and time scales.

  5. NEW SUNS IN THE COSMOS?

    Energy Technology Data Exchange (ETDEWEB)

    De Freitas, D. B.; Leao, I. C.; Lopes, C. E. Ferreira; Paz-Chinchon, F.; Canto Martins, B. L.; Alves, S.; De Medeiros, J. R. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Catelan, M. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Av. Vicuna Mackenna 4860, 782-0436 Macul, Santiago (Chile)

    2013-08-20

    The present work reports on the discovery of three stars that we have identified to be rotating Sun-like stars, based on rotational modulation signatures inferred from light curves from the CoRoT mission's Public Archives. In our analysis, we performed an initial selection based on the rotation period and position in the period-T{sub eff} diagram. This revealed that the stars CoRoT IDs 100746852, 102709980, and 105693572 provide potentially good matches to the Sun with a similar rotation period. To refine our analysis, we applied a novel procedure, taking into account the fluctuations of the features associated with photometric modulation at different time intervals and the fractality traces that are present in the light curves of the Sun and of these ''New Sun'' candidates alike. In this sense, we computed the so-called Hurst exponent for the referred stars, for a sample of 14 CoRoT stars with sub- and super-solar rotational periods, and for the Sun itself in its active and quiet phases. We found that the Hurst exponent can provide a strong discriminant of Sun-like behavior, going beyond what can be achieved with solely the rotation period itself. In particular, we find that CoRoT ID 105693572 is the star that most closely matches the solar rotation properties as far as the latter's imprints on light curve behavior are concerned. The stars CoRoT IDs 100746852 and 102709980 have significant smaller Hurst exponents than the Sun, notwithstanding their similarity in rotation periods.

  6. Nuclear medium cooling scenario in the light of new Cas A cooling data and the 2 M_sun pulsar mass measurements

    CERN Document Server

    Blaschke, D; Voskresensky, D N

    2013-01-01

    Recently, Elshamounty et al. performed a reanalysis of the surface temperature of the neutron star in the supernova remnant Cassiopeia A on the basis of Chandra data measured during last decade, and added a new data point. We show that all reliably known temperature data of neutron stars including those belonging to Cassiopea A can be comfortably explained in our "nuclear medium cooling" scenario of neutron stars. The cooling rates account for medium-modified one-pion exchange in dense matter, polarization effects in the pair-breaking-formation processes operating on superfluid neutrons and protons paired in the 1S_0 state, and other relevant processes. The emissivity of the pair-breaking-formation process in the 3P_2 state is a tiny quantity within our scenario. Crucial for a successful description of the Cassiopeia A cooling proves to be the thermal conductivity from both, the electrons and nucleons, being reduced by medium effects. Moreover, we exploit an EoS which stiffens at high densities due to an excl...

  7. The Sun's dusty interstellar environment

    Science.gov (United States)

    Sterken, Veerle

    2016-07-01

    The Sun's dusty interstellar environment Interstellar dust from our immediate interstellar neighborhood travels through the solar system at speeds of ca. 26 km/s: the relative speed of the solar system with respect to the local interstellar cloud. On its way, its trajectories are altered by several forces like the solar radiation pressure force and Lorentz force. The latter is due to the charged dust particles that fly through the interplanetary magnetic field. These trajectories differ per particle type and size and lead to varying fluxes and directions of the flow inside of the solar system that depend on location but also on phase in the solar cycle. Hence, these fluxes and directions depend strongly on the configuration of the inner regions and outer regions of the heliosphere. Several missions have measured this dust in the solar system directly. The Ulysses dust detector data encompasses 16 years of intestellar dust fluxes and approximate directions, Stardust captured returned to Earth a few of these particles sucessfully, and finally the Cassini dust detector allowed for compositional information to be obtained from the impacts on the instrument. In this talk, we give an overview of the current status of interstellar dust research through the measurements made inside of the solar system, and we put them in perspective to the knowledge obtained from more classical astronomical means. In special, we focus on the interaction of the dust with the interplanetary magnetic field, and on what we learn about the dust (and the fields) by comparing the available dust data to computer simulations of dust trajectories. Finally, we synthesize the different methods of observation, their results, and give a preview on new research opportunities in the coming year(s).

  8. Analysis of the Application of the Optical Method to the Measurements of the Water Vapor Content in the Atmosphere. I. Basic Concepts

    CERN Document Server

    Galkin, V D; Alekseeva, G A; Berger, F -H; Leiterer, U; Naebert, T; Nikanorova, I N; Novikov, V V; Pakhomov, V P; Sal'nikov, I B

    2010-01-01

    We retrieved the total content of the atmospheric water vapor from extensive sets of photometric data obtained since 1995 at Lindenberg Meteorological Observatory with star and sun photometers. Different methods of determination of the empirical parameters that are necessary for the retrieval are discussed. The instruments were independently calibrated using laboratory measurements made at Pulkovo Observatory with the VKM-100 multi-pass vacuum cell. The empirical parameters were also calculated by the simulation of the atmospheric absorption by water vapor, using the MODRAN-4 program package for different model atmospheres. The results are compared to those presented in the literature, obtained with different instruments and methods of the retrieval. The accuracy of the empirical parameters used for the power approximation that links the water vapor content with the observed absorption is analyzed. Currently, the calibration and measurement errors yield the uncertainty of about 10% in the total column water v...

  9. SunShot Initiative Portfolio Book 2014

    Energy Technology Data Exchange (ETDEWEB)

    Solar Energy Technologies Office

    2014-05-01

    The 2014 SunShot Initiative Portfolio Book outlines the progress towards the goals outlined in the SunShot Vision Study. Contents include overviews of each of SunShot’s five subprogram areas, as well as a description of every active project in the SunShot’s project portfolio as of May 2014.

  10. Magnetic Bipoles in Emerging Flux Regions on the Sun

    Science.gov (United States)

    Barth, C. S.; Livi, S. H. B.

    1990-11-01

    ABSTRACT. We analyse magnetograms and H-alpha filtergrams of an Emerging Flux Region. Small bipoles have been observed on the magnetograms emerging between opposite polarities. Separation velocities of the opposite poles for 45 bipoles observed on June 9, 1985 have been measured and are in the range 0.5 contribuciones de los bipolos emergentes. Key words: SUN-CHROMOSPHERE - SUN-MAGNETIC FIELDS

  11. The EUV emission from sun-grazing comets

    OpenAIRE

    Bryans, Paul; Pesnell, W Dean

    2012-01-01

    The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) has observed two sun-grazing comets as they passed through the solar atmosphere. Both passages resulted in a measurable enhancement of Extreme Ultraviolet (EUV) radiance in several of the AIA bandpasses. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Molecules in the comet rapidly sublimate as it approaches the Sun. They are th...

  12. Aerosol Properties under Air Quality Control Measures of APEC 2014 in Beijing

    Science.gov (United States)

    Chen, X.; Xu, H.; Lv, Y.; Xie, Y.; Li, K.; Li, Z.; Li, D.; Ma, Y.; Mei, X.

    2015-12-01

    Because the economic and society were developing fast in the middle of last century, Los Angeles and London both were polluted by photochemical smog, which massacred thousands of people. Now, many regions are often covered by heavy haze in those large developing countries, especially in China and India. The Asia-Pacific Economic Cooperation (APEC) was held in Beijing during 5-11 November 2014. Beijing, Hebei, Tianjin, Shandong, Shanxi, Inner Mongolia reduced air pollution emissions for the APEC 2014 meeting held in Beijing. Only in Hebei province, there were 1028 factories stopped or restricted and 881 construction sites stopped. Half of the cars were prohibited driving even in the Zibo city which is 400 km far from Beijing. For scientific aims, these control measures were indeed a huge and uncommon atmospheric experiment led by the government. During the experiment, what did the "APEC Blue" mean? We analyzed aerosol properties with the data of an AERONET site in Beijing which is located 500m far from the main reception hall of APEC 2014. The Cimel solar photometers can give a series parameters of aerosol and water vapor. In this paper, we used CE318 solar photometer which is the main instrument of NASA AERONET. The CE318 of RADI belongs to the Chinese SONET (Sun-sky radiometer Observation NETwork) too. We analyzed the total, coarse and fine Aerosol Optical Depth (AOD), Fine-Mode Fraction (FMF) and Ångström exponent, Size Distribution and Real Refractive Index. In conclusion, the aerosol properties were analysed with the measurements of a sun photometer. During the APEC 2014, AOD decreased obviously with a 0.27 mean value compared with the annual mean 0.7. Around Beijing, the southern is polluted emission area including the cross part of Shandong, Shanxi, Hebei, Henan four provinces, and the northern is clean for less fine mode particles emission in the large Inner Mongolia province. In fact, during the APEC 2014, the weather condition was not good for the

  13. Watching the Sun to Improve Exoplanet Detection

    Science.gov (United States)

    Kohler, Susanna

    2015-12-01

    Looking for stars that wobble is one of the key ways by which we detect exoplanets: the gravitational pull of planets cause tiny variations in stars radial velocities. But our ability to detect Earth twins is currently limited by our ability to distinguish between radial-velocity variations caused by exoplanets, and those caused by noise from the star itself. A team of scientists has recently proposed that the key to solving this problem may be to examine our own star.Precision Amid NoiseThe radial-velocity technique works well for detecting large planets on close orbits, but detecting an Earth twin requires being able to detect star motion on the order of 10 cm/s! This precision is hard to reach, because activity on the stellar surface i.e., sunspots, plages (bright spots), or granulation can also cause variations in the measured radial velocity for the star, obscuring the signature of a planet.Because the stars were examining arent resolved, we cant track the activity on their surfaces so how can we better understand the imprint that stellar activity has on radial-velocity measurements? A team of scientists has come up with a clever approach: examine the Sun as though it were a distant star.Wealth of InformationThe team, led by Xavier Dumusque (Branco-Weiss Fellow at the Harvard-Smithsonian Center for Astrophysics) and David F. Phillips (Harvard-Smithsonian Center for Astrophysics), has begun a project to observe the Sun with a ground-based solar telescope. The telescope observes the full disk of the Sun and feeds the data into the HARPS-N spectrograph in Spain, a spectrograph normally used for radial-velocity measurements of other stars in the hunt for exoplanets.But the team has access to other data about the Sun, too: information from satellites like the Solar Dynamics Observatory and SORCE about the solar activity and total irradiance during the time when the spectra were taken. Dumusque and collaborators have combined all of this information, during a week

  14. The Sun: Our Nearest Star

    Science.gov (United States)

    Adams, M. L.; Six, N. Frank (Technical Monitor)

    2002-01-01

    We have in our celestial backyard, a prime example of a variable star. The Sun, long thought to be "perfect" and unvarying, began to reveal its cycles in the early 1600s as Galileo Galilei and Christoph Scheiner used a telescope to study sunspots. For the past four hundred years, scientists have accumulated data, showing a magnetic cycle that repeats, on average, every eleven (or twenty-two) years. In addition, modern satellites have shown that the energy output at radio and x-ray wavelengths also varies with this cycle. This talk will showcase the Sun as a star and discuss how solar studies may be used to understand other stars.

  15. On Sun-to-Earth Propagation of Coronal Mass Ejections

    CERN Document Server

    Liu, Ying D; Lugaz, Noé; Möstl, Christian; Davies, Jackie A; Bale, Stuart D; Lin, Robert P

    2013-01-01

    We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation. Our comparison between different techniques (and data sets) also has important implications for CME observations and their interpretations. Future CME observations and space weather forecasting are discussed based on these results. See detail in the PDF.

  16. Detecting Close-In Extrasolar Giant Planets with the Kepler Photometer via Scattered Light

    Science.gov (United States)

    Jenkins, J. M.; Doyle, L. R.; Kepler Discovery Mission Team

    2003-05-01

    NASA's Kepler Mission will be launched in 2007 primarily to search for transiting Earth-sized planets in the habitable zones of solar-like stars. In addition, it will be poised to detect the reflected light component from close-in extrasolar giant planets (CEGPs) similar to 51 Peg b. Here we use the DIARAD/SOHO time series along with models for the reflected light signatures of CEGPs to evaluate Kepler's ability to detect such planets. We examine the detectability as a function of stellar brightness, stellar rotation period, planetary orbital inclination angle, and planetary orbital period, and then estimate the total number of CEGPs that Kepler will detect over its four year mission. The analysis shows that intrinsic stellar variability of solar-like stars is a major obstacle to detecting the reflected light from CEGPs. Monte Carlo trials are used to estimate the detection threshold required to limit the total number of expected false alarms to no more than one for a survey of 100,000 stellar light curves. Kepler will likely detect 100-760 51 Peg b-like planets by reflected light with orbital periods up to 7 days. LRD was supported by the Carl Sagan Chair at the Center for the Study of Life in the Universe, a division of the SETI Institute. JMJ received support from the Kepler Mission Photometer and Science Office at NASA Ames Research Center.

  17. Low-cost, high-performance and efficiency computational photometer design

    Science.gov (United States)

    Siewert, Sam B.; Shihadeh, Jeries; Myers, Randall; Khandhar, Jay; Ivanov, Vitaly

    2014-05-01

    Researchers at the University of Alaska Anchorage and University of Colorado Boulder have built a low cost high performance and efficiency drop-in-place Computational Photometer (CP) to test in field applications ranging from port security and safety monitoring to environmental compliance monitoring and surveying. The CP integrates off-the-shelf visible spectrum cameras with near to long wavelength infrared detectors and high resolution digital snapshots in a single device. The proof of concept combines three or more detectors into a single multichannel imaging system that can time correlate read-out, capture, and image process all of the channels concurrently with high performance and energy efficiency. The dual-channel continuous read-out is combined with a third high definition digital snapshot capability and has been designed using an FPGA (Field Programmable Gate Array) to capture, decimate, down-convert, re-encode, and transform images from two standard definition CCD (Charge Coupled Device) cameras at 30Hz. The continuous stereo vision can be time correlated to megapixel high definition snapshots. This proof of concept has been fabricated as a fourlayer PCB (Printed Circuit Board) suitable for use in education and research for low cost high efficiency field monitoring applications that need multispectral and three dimensional imaging capabilities. Initial testing is in progress and includes field testing in ports, potential test flights in un-manned aerial systems, and future planned missions to image harsh environments in the arctic including volcanic plumes, ice formation, and arctic marine life.

  18. Day the sun went out

    CERN Multimedia

    2007-01-01

    "A new british sci-fi movie envisages the death of the sun not in billions of years, but in decades. And, amazingly, the film's scientific adviser says this may not be so far from the truth..." (1/2 page)

  19. Effects of Early Sun Exposure

    Science.gov (United States)

    ... can be harmful. It can lead to:Skin changes. Some skin cells with melanin can form a clump. This creates freckles and moles. Over time, these can develop cancer.Early aging. Time spent in the sun makes your skin age faster than normal. Signs of this are wrinkled, tight, or leathery ...

  20. Tracking Planets around the Sun

    Science.gov (United States)

    Riddle, Bob

    2008-01-01

    In earlier columns, the celestial coordinate system of hour circles of right ascension and degrees of declination was introduced along with the use of an equatorial star chart (see SFA Star Charts in Resources). This system shows the planets' motion relative to the ecliptic, the apparent path the Sun follows during the year. An alternate system,…

  1. Tracking Planets around the Sun

    Science.gov (United States)

    Riddle, Bob

    2008-01-01

    In earlier columns, the celestial coordinate system of hour circles of right ascension and degrees of declination was introduced along with the use of an equatorial star chart (see SFA Star Charts in Resources). This system shows the planets' motion relative to the ecliptic, the apparent path the Sun follows during the year. An alternate system,…

  2. The Sun and climate

    Science.gov (United States)

    ,

    2000-01-01

    Many geologic records of climatic and environmental change based on various proxy variables exhibit distinct cyclicities that have been attributed to extraterrestrial forcing. The best known of these are the changes in Earth’s orbital geometry called Milankovitch Cycles, with periodicities of tens to hundreds of thousands of years. However, many cycles seem to have subMilankovitch periodicities, commonly on decadal and centennial scales, similar to those of known solar cycles. A direct connection between solar irradiance (solar constant) and weather and climate has been suggested for more than 100 years but generally rejected by most scientists, who assume that the effect of solar variations would be small. However, recent satellite radiometer measurements and modeling studies indicate that small changes in total solar irradiance could produce global temperature changes of the magnitude suggested for climatic events such as the Little Ice Age (A.D. 1550–1700).

  3. Dissemination of go sun smart in outdoor recreation: effect of program exposure on sun protection of guests at high-altitude ski areas.

    Science.gov (United States)

    Walkosz, Barbara J; Buller, David B; Andersen, Peter A; Scott, Michael D; Dignan, Mark B; Cutter, Gary R; Liu, Xia; Maloy, Julie A

    2014-09-01

    Go Sun Smart is a theory-based health communication program designed to influence sun-protection behaviors of employees and guests at high-altitude ski areas to reduce skin cancer risk. The effects of Go Sun Smart, in a Phase IV dissemination randomized posttest-only trial, on sun-protection behaviors of ski area guests are reported. Program use was assessed by on-site observation and guest message exposure, and sun protection was measured in intercept surveys at ski areas. Dissemination strategy-enhanced versus basic-was not significantly related to sun safety practices. Additional analyses examined the relation between message exposure and guests' sun safety practices. Ski areas displaying at least 6 Go Sun Smart materials in guest-only areas and 9 Go Sun Smart materials throughout the area increased guests' message exposure. Higher message exposure within the high-use ski areas was associated with improved sun protection by guests but not within the low-use ski areas. The authors underscore the importance of program implementation and message exposure on the success of evidence-based health communication efforts applied industrywide.

  4. Investigation of possible sun-weather relationships

    Energy Technology Data Exchange (ETDEWEB)

    Businger, S

    1978-01-01

    Statistical correlations between anomalous solar activity (as denoted by large solar flares, active plages, and interplanetary magnetic sector boundaries) and the circulation of the troposphere are reviewed. Two indices (measuring atmospheric vorticity and mean zonal geostrophic flow in the northern hemisphere) are analyzed in an effort to reveal possible sun-weather relationships. The result of this analysis provides no additional statistical evidence for a connection between solar activity and the weather. Finally, physical mechanisms that have been suggested to explain the claimed correlations are discussed.

  5. The Sun Radio Imaging Space Experiment (SunRISE) Mission

    Science.gov (United States)

    Lazio, Joseph; Kasper, Justin; Maksimovic, Milan; Alibay, Farah; Amiri, Nikta; Bastian, Tim; Cohen, Christina; Landi, Enrico; Manchester, Ward; Reinard, Alysha; Schwadron, Nathan; Cecconi, Baptiste; Hallinan, Gregg; Hegedus, Alex; Krupar, Vratislav; Zaslavsky, Arnaud

    2017-04-01

    Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 RS. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (ν ≳ 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (≲ 3RS). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  6. Intercomparison Study of the CAPS PMex (Cavity Attenuated Phase Shift Particle Light Extinction Monitor) with the combination of an Integrating Nephelometer and a Particle Soot Absorption Photometer

    Science.gov (United States)

    Petzold, A.; Onasch, T.; Kebabian, P.; Freedman, A.

    2012-10-01

    An evaluation of the Cavity Attenuated Phase Shift particle light extinction monitor (CAPS PMex) by means of a combination of a 3-wavelength Integrating Nephelometer (NEPH; TSI Model 3563) and a 3-wavelength filter-based Particle Soot Absorption Photometer (PSAP) was carried out using both laboratory generated test particles and ambient aerosols. An accurate determination of a fixed pathlength correction for the CAPS PMex was made by comparing extinction measurements using polystyrene latex (PSL) spheres in combination with Mie scattering calculations to account for the presence of PSL conglomerates. These studies yielded a linear instrument response over the investigated dynamical range from 20 to 450 M m-1 (10-6 m-1) with a linear correlation coefficient of R2 > 0.98. The adjustment factor was determined to be 1.05 times that previously reported. Correlating CAPS extinction to extinction measured by the NEPH-PSAP combination using laboratory-generated polydisperse mixtures of purely scattering ammonium sulfate and highly absorbing black carbon provided a linear regression line with slope m = 0.99 (R2 = 0.996) for single-scattering albedo values (λ = 630 nm) ranging from 0.35 (black carbon) to 1.00 (ammonium sulfate). For ambient aerosol, light extinction measured by CAPS PMex was highly correlated (R2 = 0.995) to extinction measured by the NEPH-PSAP combination with slope m = 0.95.

  7. Ground-based aerosol measurements during CHARMEX/ADRIMED campaign at Granada station

    Science.gov (United States)

    Granados-Muñoz, Maria Jose; Bravo-Aranda, Juan Antonio; Navas-Guzman, Francisco; Guerro-Rascado, Juan Luis; Titos, Gloria; Lyamani, Hassan; Valenzuela, Antonio; Cazorla, Alberto; Olmo, Francisco Jose; Mallet, Marc; Alados-Arboledas, Lucas

    2015-04-01

    In the framework of ChArMEx/ADRIMED (Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr/; Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) projects, a field experiment based on in situ and remote sensing measurements from surface and airborne platforms was performed. The ADRIMED project aimed to capture the high complexity of the Mediterranean region by using an integrated approach based on intensive experimental field campaign and spaceborne observations, radiative transfer calculations and climate modelling with Regional Climate Models better adapted than global circulation models. For this purpose, measurements were performed at different surface super-sites (including Granada station) over the Occidental Mediterranean region during summer 2013 for creating an updated database of the physical, chemical, optical properties and the vertical distribution of the major "Mediterranean aerosols". Namely, measurements at Granada station were performed on 16 and 17 July 2013, in coincidence with the overpasses of the ATR aircraft over the station. The instrumentation used for the campaign includes both remote sensing instruments (a multiwavelength Raman lidar and a sun photometer) and in-situ measurements (a nephelometer, a Multi-Angle Absorption Photometer (MAAP), an Aerodynamic particle sizer (APS), a high volume sampler of PM10 and an aethalometer). During the measurement period a mineral dust event was detected, with similar dust load on both days. According to in-situ measurements, the event reached the surface level on 16 of June. Vertically resolved lidar measurements indicated presence of mineral dust layers up to 5 km asl both on 16 and 17 June 2013. Temporal evolution analysis indicated that on 17 June the dust layer decoupled from the boundary layer and disappeared around 14:00 UTC. In addition, lidar and sun-photometer data were used to retrieve volume concentration profiles by means of LIRIC (Lidar

  8. Tanel Padar & The Sun veab õhukitarri

    Index Scriptorium Estoniae

    2008-01-01

    Õhukitarri Eesti meistrivõistlustest 19. apr. Tallinnas Rock Cafés (võistluste eestvedajaks on ansambel Tanel Padar & The Sun, kes samas esitleb oma esimest ingliskeelset albumit "Here Comes The Sun")

  9. Tanel Padar & The Sun veab õhukitarri

    Index Scriptorium Estoniae

    2008-01-01

    Õhukitarri Eesti meistrivõistlustest 19. apr. Tallinnas Rock Cafés (võistluste eestvedajaks on ansambel Tanel Padar & The Sun, kes samas esitleb oma esimest ingliskeelset albumit "Here Comes The Sun")

  10. Gearbox Reliability Collaborative: Test and Model Investigation of Sun Orbit and Planet Load Share in a Wind Turbine Gearbox; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    LaCava, W.; Keller, J.; McNiff, B.

    2012-04-01

    This paper analyzes experimental measurement of the sun gear orbit in dynamometer testing and describes its relation to the other measured responses of the planetary stage. The relation of the sun orbit to component runout, component flexibility, gear coupling alignment, planet load share, and planet position error will be investigated. Equations describing the orbit of the sun gear in the test cases are derived. Rigid and flexible multibody models of the full gearbox are investigated and compared to sun and planet measurements. This paper shows that the sun gear's path may be influenced by gear coupling responses and gearbox structural flexibilities.

  11. Caddo Sun Accounts across Time and Place

    Science.gov (United States)

    Gerona, Carla

    2012-01-01

    Billy Day, a Tunica/Biloxi, recently described the significance of the sun for Caddoan people. Day quoted an "old Caddo relative" of his who said: "I used to go outside and hold my hands up and bless myself with the sun--'a'hat.' Well, I can't do that anymore because they say we are sun worshipers. We didn't worship the sun. We worshiped what was…

  12. Global Warming Blame the Sun

    CERN Document Server

    Calder, N

    1997-01-01

    Concern about climate change reaches a political peak at a UN conference in Kyoto, 1-10 December, but behind the scenes the science is in turmoil. A challenge to the hypothesis that greenhouse gases are responsible for global warming comes from the discovery that cosmic rays from the Galaxy are involved in making clouds (Svensmark and Friis-Christensen, 1997). During the 20th Century the wind from the Sun has grown stronger and the count of cosmic rays has diminished. With fewer clouds, the EarthÕs surface has warmed up. This surprising mechanism explains the link between the Sun and climate change that astronomers and geophysicists have suspected for 200 years.

  13. Probing Black Carbon-containing Particle Microphysics with the Single-Particle Soot Photometer (SP2)

    Science.gov (United States)

    Sedlacek, A. J.; Lewis, E. R.; Onasch, T. B.; Lambe, A. T.; Davidovits, P.; Kleinman, L. I.

    2012-12-01

    Knowledge of the structure and mixing state of black-carbon containing particles is important for calculating their radiative forcing and provides insight into their source and life cycle. Recently analysis of black carbon-containing particles has demonstrated that for a fraction of such particles, the black carbon may reside on or near the surface of the particle as opposed to the traditional core-shell configuration typically assumed in which the black carbon core is surrounded by a shell of non-refractory material. During the DOE-sponsored Aerosol Lifecycle field campaign held in summer, 2011 at Brookhaven National Laboratory on Long Island, NY, episodes were encountered in which a high fraction of particles containing black carbon had such configurations, and these episodes corresponded to air masses that contained biomass burning plumes (Sedlacek et al., 2012). Subsequent analysis found other episodes in field campaigns in Colorado and California in which high fractions this configuration corresponded to biomass burning plumes. In an effort to evaluate this interpretation and explore formation mechanisms, a series of laboratory-based experiments examining the coagulation of regal black (surrogate for collapsed soot) with model non-refractory coatings [dioctyl sebacate (surrogate for organic aerosols with liquid-like character) and deliquesced ammonium sulfate (solid)] were carried out. The results of these experiments and their potential implications on black carbon radiative forcing will be discussed. Sedlacek, III, Arthur, E. R. Lewis, L. I. Kleinman, J. Xu and Q. Zhang (2012), Determination of and Evidence for Non-core-shell structure of particles containing black carbon using the single particle soot photometer (SP2). Geophys. Res. Lett., 39 L06802, doi:10.1029/2012GL050905

  14. Revisiting SU(N) integrals

    CERN Document Server

    Zuber, Jean-Bernard

    2016-01-01

    In this note, I revisit integrals over $\\SU(N)$ of the form $ \\int DU\\, U_{i_1j_1}\\cdots U_{i_pj_p}\\Ud_{k_1l_1}\\cdots \\Ud_{k_nl_n}$. While the case $p=n$ is well known, it seems that explicit expressions for $p=n+N$ had not appeared in the literature. Similarities and differences, in particular in the large $N$ limit, between the two cases are discussed

  15. Coherent States with SU(N) Charges

    CERN Document Server

    Mathur, M; Mathur, Manu; Paul, Samir K.

    2003-01-01

    We define coherent states carrying SU(N) charges by exploiting generalized Schwinger boson representation of SU(N) Lie algebra. These coherent states are defined on $2 (2^{N - 1} - 1)$ complex planes. They satisfy continuity property and provide resolution of identity. We also exploit this technique to construct the corresponding non-linear SU(N) coherent states.

  16. The Sun Rises on the Solar Sector

    OpenAIRE

    Ahmad, Reyaz A.

    2009-01-01

    Energy from the sun is abundant and free. Solar energy is in essence electromagnetic radiation emitted from the sun. Earth's climate, hydrologic systems, and ecosystems all derive from the sun. Other forms of renewable power such as wind, wave, biomass, and hydro are an indirect function of solar radiation.

  17. The Sun A User's Manual

    CERN Document Server

    Vita-Finzi, Claudio

    2008-01-01

    The Sun is an account of the many ways in which our nearest star affects our planet, how its influence has changed over the last few centuries and millennia, and the extent to which we can predict its future impact. The Sun's rays foster the formation of Vitamin D by our bodies, but it can also promote skin cancer, cataracts, and mutations in our DNA. Besides providing the warmth and light essential to most animal and plant life, solar energy contributes substantially to global warming. Although the charged particles of the solar wind shield us from harmful cosmic rays, solar storms may damage artificial satellites and cripple communication systems and computer networks. The Sun is the ideal renewable energy source, but its exploitation is still bedevilled by the problems of storage and distribution. Our nearest star, in short, is a complex machine which needs to be treated with caution, and this book will equip every reader with the knowledge that is required to understand the benefits and dangers it can bri...

  18. The faint young Sun problem

    CERN Document Server

    Feulner, Georg

    2012-01-01

    For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the `faint young Sun problem'. For the early Earth, models of stellar evolution predict a solar energy input to the climate system which is about 25% lower than today. This would result in a completely frozen world over the first two billion years in the history of our planet, if all other parameters controlling Earth's climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun prob...

  19. A method for lunar roving vehicle position determination from three landmark observations with a sun compass

    Science.gov (United States)

    Blucker, T. J.; Stimmel, G. L.

    1971-01-01

    A simplified method is described for determining the position of the lunar roving vehicle on the lunar surface during Apollo 15. The method is based upon sun compass azimuth measurements of three lunar landmarks. The difference between the landmark azimuth and the sun azimuth is measured and the resulting data are voice relayed to the Mission Control Center for processing.

  20. Sun Savvy Students: Free Teaching Resources from EPA's SunWise Program

    Science.gov (United States)

    Hall-Jordan, Luke

    2008-01-01

    With summer in full swing and the sun is naturally on our minds, what better time to take advantage of a host of free materials provided by the U.S. Environmental Protection Agency's Sun Wise program. Sun Wise aims to teach students and teachers about the stratospheric ozone layer, ultraviolet (UV) radiation, and how to be safe while in the Sun.…

  1. Arctic Black Carbon Loading and Profile Using the Single-Particle Soot Photometer (SP2) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, Arthur J [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-05-01

    One of the major issues confronting aerosol climate simulations of the Arctic and Antarctic cryospheres is the lack of detailed data on the vertical and spatial distribution of aerosols with which to test these models. This is due, in part, to the inherent difficulty of conducting such measurements in extreme environments. However given the pronounced sensitivity of the polar regions to radiative balance perturbations, it is incumbent upon our community to better understand and quantify these perturbations, and their unique feedbacks, so that robust model predictions of this region can be realized. One class of under-measured radiative forcing agents in the polar region is the absorbing aerosol—black carbon and brown carbon. Black carbon (BC; also referred to as light-absorbing carbon [LAC], refractory black carbon [rBC], and soot) is second only to CO2 as a positive forcing agent. Roughly 60% of BC emissions can be attributed to anthropogenic sources (fossil fuel combustion and open-pit cooking), with the remaining fraction being due to biomass burning. Brown carbon (BrC), a major component of biomass burning, collectively refers to non-BC carbonaceous aerosols that typically possess minimal light absorption at visible wavelengths but exhibit pronounced light absorption in the near-ultraviolet (UV) spectrum. Both species can be sourced locally or be remotely transported to the Arctic region and are expected to perturb the radiative balance. The work conducted in this field campaign addresses one of the more glaring deficiencies currently limiting improved quantification of the impact of BC radiative forcing in the cryosphere: the paucity of data on the vertical and spatial distributions of BC. By expanding the Gulfstream aircraft (G-1) payload for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility-sponsored ACME-V campaign to include the Single-Particle Soot Photometer (SP2)) and leveraging the ACME-V campaign

  2. Dimming of the Mid-20th Century Sun

    CERN Document Server

    Foukal, Peter

    2015-01-01

    Advances in understanding of the white light faculae measured at the Royal Greenwich Observatory from 1874 to 1976 suggest that they offer a more direct measure of solar brightening by small diameter photospheric magnetic flux tubes than do chromospheric proxies. Proxies such as the area of Ca K plages, the Mg index or the microwave flux include many dark photospheric structures as well as pores and sunspots. Our reconstruction of variation in total solar irradiance,TSI,based on the faculae indicates that the sun dimmed by almost 0.1 percent in the mid- twentieth century rather than brightening as represented in previous reconstructions. This dimmimg at the sun's highest activity level since the seventeenth century is consistent with the photometric behavior observed in somewhat younger sun like stars. The prolonged TSI decrease may have contributed more to the cooling of climate between about 1940 and 1970 than present models indicate.

  3. Evaluation of Daytime Measurements of Aerosols and Water Vapor made by an Operational Raman Lidar over the Southern Great Plains

    Science.gov (United States)

    Ferrare, Richard; Turner, David; Clayton, Marian; Schmid, Beat; Covert, David; Elleman, Robert; Orgren, John; Andrews, Elisabeth; Goldsmith, John E. M.; Jonsson, Hafidi

    2006-01-01

    Raman lidar water vapor and aerosol extinction profiles acquired during the daytime over the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in northern Oklahoma (36.606 N, 97.50 W, 315 m) are evaluated using profiles measured by in situ and remote sensing instruments deployed during the May 2003 Aerosol Intensive Operations Period (IOP). The automated algorithms used to derive these profiles from the Raman lidar data were first modified to reduce the adverse effects associated with a general loss of sensitivity of the Raman lidar since early 2002. The Raman lidar water vapor measurements, which are calibrated to match precipitable water vapor (PWV) derived from coincident microwave radiometer (MWR) measurements were, on average, 5-10% (0.3-0.6 g/m(exp 3) higher than the other measurements. Some of this difference is due to out-of-date line parameters that were subsequently updated in the MWR PWV retrievals. The Raman lidar aerosol extinction measurements were, on average, about 0.03 km(exp -1) higher than aerosol measurements derived from airborne Sun photometer measurements of aerosol optical thickness and in situ measurements of aerosol scattering and absorption. This bias, which was about 50% of the mean aerosol extinction measured during this IOP, decreased to about 10% when aerosol extinction comparisons were restricted to aerosol extinction values larger than 0.15 km(exp -1). The lidar measurements of the aerosol extinction/backscatter ratio and airborne Sun photometer measurements of the aerosol optical thickness were used along with in situ measurements of the aerosol size distribution to retrieve estimates of the aerosol single scattering albedo (omega(sub o)) and the effective complex refractive index. Retrieved values of omega(sub o) ranged from (0.91-0.98) and were in generally good agreement with omega(sub o) derived from airborne in situ measurements of scattering and absorption. Elevated aerosol

  4. Volcanic ash from Iceland over Munich: mass concentration retrieved from ground-based remote sensing measurements

    Science.gov (United States)

    Gasteiger, J.; Gro{ß}, S.; Freudenthaler, V.; Wiegner, M.

    2011-03-01

    Volcanic ash plumes, emitted by the Eyjafjallajökull volcano (Iceland) in spring 2010, were observed by the lidar systems MULIS and POLIS in Maisach (near Munich, Germany), and by a CIMEL Sun photometer and a JenOptik ceilometer in Munich. We retrieve mass concentrations of volcanic ash from the lidar measurements; spectral optical properties, i.e.~extinction coefficients, backscatter coefficients, and linear depolarization ratios, are used as input for an inversion. The inversion algorithm searches for model aerosol ensembles with optical properties that agree with the measured values within their uncertainty ranges. The non-sphericity of ash particles is considered by assuming spheroids. Optical particle properties are calculated using the T-matrix method supplemented by the geometric optics approach. The lidar inversion is applied to observations of the pure volcanic ash plume in the morning of 17 April 2010. We find 1.45 g m-2 for the ratio between the mass concentration and the extinction coefficient at λ = 532 nm, assuming an ash density of 2.6 g cm-3. The uncertainty range for this ratio is from 0.87 g m-2 to 2.32 g m-2. At the peak of the ash concentration over Maisach the extinction coefficient at λ = 532 nm was 0.75 km-1 (1-h-average), which corresponds to a maximum mass concentration of 1.1 mg m-3 (0.65 to 1.8 mg m-3). Model calculations show that particle backscatter at our lidar wavelengths (λ ≤ 1064 nm), and thus the lidar retrieval, is hardly sensitive to large particles (r ≳ 3 μm); large particles, however, may contain significant amounts of mass. Therefore, as an independent cross check of the lidar retrieval and to investigate the presence of large particles in more detail, we model ratios of sky radiances in the aureole of the Sun and compare them to measurements of the CIMEL. These ratios are sensitive to particles up to r ≈ 10 μm. This approach confirms the mass concentrations from the lidar retrieval. We conclude that synergistic

  5. Cirrus Microphysical Properties from Stellar Aureole Measurements, Phase I

    Energy Technology Data Exchange (ETDEWEB)

    DeVore, J. G.; Kristl, J. A.; Rappaport, S. A.

    2012-04-20

    While knowledge of the impact of aerosols on climate change has improved significantly due to the routine, ground-based, sun photometer measurements of aerosols made at AERONET sites world-wide, the impact of cirrus clouds remains much less certain because they occur high in the atmosphere and are more difficult to measure. This report documents work performed on a Phase I SBIR project to retrieve microphysical properties of cirrus ice crystals from stellar aureole imagery. The Phase I work demonstrates that (1) we have clearly measured stellar aureole profiles; (2) we can follow the aureole profiles out to ~1/4 degree from stars (~1/2 degree from Jupiter); (3) the stellar aureoles from cirrus have very distinctive profiles, being flat out to a critical angle, followed by a steep power-law decline with a slope of ~-3; (4) the profiles are well modeled using exponential size distributions; and (5) the critical angle in the profiles is ~0.12 degrees, (6) indicating that the corresponding critical size ranges from ~150 to ~200 microns. The stage has been set for a Phase II project (1) to proceed to validating the use of stellar aureole measurements for retrieving cirrus particle size distributions using comparisons with optical property retrievals from other, ground-based instruments and (2) to develop an instrument for the routine, automatic measurement of thin cirrus microphysical properties.

  6. A new perspective on quiet Sun magnetism

    Institute of Scientific and Technical Information of China (English)

    LITES Bruce William

    2009-01-01

    The Hinode mission has provided us with a new, quantitative view of the magnetism of the quiet Sun. It has revealed that the quiet internetwork areas are blanketed by horizontal fields that appear at first sight to have more flux than the vertical fields resolved on the same 0.3″ size scale. These measurements point to the possibility that the horizontal fields might be the primary source of the "hidden turbulent flux" of the quiet Sun anticipated from Hanle effect depolarization. In this paper, evidence is presented suggesting that the "seething" horizontal fields observed by Harvey in 2007 and the horizontal fields revealed by Hinode are the same phenomenon. Because the seething fields appear to be of uniform fluctuation over the whole disk, the phenomenon is most likely not associated with the dynamo source of solar activity. Thus, the small-scale "hidden turbulent flux" lends support to the notion of a local solar dynamo acting on granular sizes and time scales.

  7. Promoting sun safety among zoo visitors.

    Science.gov (United States)

    Mayer, J A; Lewis, E C; Eckhardt, L; Slymen, D; Belch, G; Elder, J; Engelberg, M; Eichenfield, L; Achter, A; Nichols, T; Walker, K; Kwon, H; Talosig, M; Gearen, C

    2001-09-01

    Each year, millions of children visit zoological parks, where they are exposed to long bouts of ultraviolet radiation (UVR). We conducted a study in the winter and replicated it in the summer to evaluate an intervention for reducing UVR exposure during the zoo visit. Each study used a nonequivalent control group design: one zoological site received the intervention and a second received evaluation only. Key outcome measures consisted of observed prevalence of hat use by exiting children (N = 8,721 and 8,524, respectively, in winter and summer studies) and purchase rates of sunscreen and hats in zoo gift shops. Intervention consisted of tip sheets for parents, children's activities, prompts, and discounts off the price of sunscreen and sun-protective hats. In the summer study, sales of both sunscreen and target hats increased significantly at the intervention site relative to the control site, whereas in the winter study, only sunscreen sales at the intervention site had a significant (relative) increase. Children's hat use increased significantly at the intervention site, but only in the winter study. The multicomponent program was effective in promoting purchases of sun-safe items, but its impact on children's hat use was inconclusive. Copyright 2001 American Health Foundation and Academic Press.

  8. Light Work: Contemporary Artists Consider the Sun

    Science.gov (United States)

    Cummins, Rebecca

    2005-01-01

    Modern day life and timekeepers have profoundly affected the way we conceptualize time and our position in the universe. Over the past year, I have been investigating the apparent movement of the Sun both sculpturally and photographically. In this paper, I discuss my collaborations with Woody Sullivan and highlight several of the sundials, both gigantic and intimate, created by University of Washington students in the class Where is Noon? Regarding Giant Sundials that we co-taught in Spring 2003. I have continued to develop artistic approaches to solar events. Some of these sunworks have not been designed specifically to measure the exact time of day as a classic sundial does, but to stimulate a greater awareness of our subjective and paradoxical relationship to nature and technology. Other, almost domestic, poetic, humorous or intimate ways of interacting with science and technology are being actively explored. I will also provide a background to previous works I have done in relation to the Sun and optics, and briefly mention artists who are using astronomical events as a point of departure.

  9. Micro technology based sun sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Pedersen, Martin; Fléron, René

    2003-01-01

    There is increasing interest among universities in the scientific and educational possibilities of picosatellites base on the CubeSat 5 concept. Due to sever mass and dimension constraints place on this type of satellites, new approaches and ideas regarding different systems arises to accommodate...... DTUsat sun sensors are needed along with a magnetometer to obtain unambiguous attitude determination for the ACDS and the payloads - an electrodynamic tether and a camera. The accuracy needed was not obtainable by employing conventional attitude sensors. Hence a linear slit sensor was designed...

  10. Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. I. The Stellar Calibrator Sample and the 24 micron Calibration

    CERN Document Server

    Engelbracht, C W; Su, K Y L; Rho, J; Rieke, G H; Muzerolle, J; Padgett, D L; Hines, D C; Gordon, K D; Fadda, D; Noriega-Crespo, A; Kelly, D M; Latter, W B; Hinz, J L; Misselt, K A; Morrison, J E; Stansberry, J A; Shupe, D L; Stolovy, S; Wheaton, Wm A; Young, E T; Neugebauer, G; Wachter, S; Pérez-González, P G; Frayer, D T; Marleau, F R

    2007-01-01

    We present the stellar calibrator sample and the conversion from instrumental to physical units for the 24 micron channel of the Multiband Imaging Photometer for Spitzer (MIPS). The primary calibrators are A stars, and the calibration factor based on those stars is 4.54*10^{-2} MJy sr^{-1} (DN/s)^{-1}, with a nominal uncertainty of 2%. We discuss the data-reduction procedures required to attain this accuracy; without these procdures, the calibration factor obtained using the automated pipeline at the Spitzer Science Center is 1.6% +/- 0.6% lower. We extend this work to predict 24 micron flux densities for a sample of 238 stars which covers a larger range of flux densities and spectral types. We present a total of 348 measurements of 141 stars at 24 micron. This sample covers a factor of ~460 in 24 micron flux density, from 8.6 mJy up to 4.0 Jy. We show that the calibration is linear over that range with respect to target flux and background level. The calibration is based on observations made using 3-second e...

  11. Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. III. An Asteroid-based Calibration of MIPS at 160 microns

    CERN Document Server

    Stansberry, J A; Bhattacharya, B; Engelbracht, C W; Rieke, G H; Marleau, F R; Fadda, D; Frayer, D T; Noriega-Crespo, A; Wachter, S; Young, E T; Müller, T G; Kelly, D M; Blaylock, M; Henderson, D; Neugebauer, G; Beeman, J W; Haller, E E

    2007-01-01

    We describe the absolute calibration of the Multiband Imaging Photometer for Spitzer (MIPS) 160 micron channel. After the on-orbit discovery of a near-IR ghost image that dominates the signal for sources hotter than about 2000 K, we adopted a strategy utilizing asteroids to transfer the absolute calibrations of the MIPS 24 and 70 micron channels to the 160 micron channel. Near-simultaneous observations at all three wavelengths are taken, and photometry at the two shorter wavelengths is fit using the Standard Thermal Model. The 160 micron flux density is predicted from those fits and compared with the observed 160 micron signal to derive the conversion from instrumental units to surface brightness. The calibration factor we derive is 41.7 MJy/sr/MIPS160 (MIPS160 being the instrumental units). The scatter in the individual measurements of the calibration factor, as well as an assesment of the external uncertainties inherent in the calibration, lead us to adopt an uncertainty of 5.0 MJy/sr/MIPS160 (12%) for the ...

  12. Cosmic Ray Sun Shadow in Soudan 2 Underground Muon Flux

    CERN Document Server

    Allison, W W M; Ayres, D S; Barrett, W L; Bode, C; Border, P M; Brooks, C B; Cobb, J H; Cotton, R J; Courant, H; Demuth, D M; Fields, T H; Gallagher, H R; García-García, C; Goodman, M C; Gran, R; Joffe-Minor, T M; Kafka, T; Kasahara, S M; Leeson, W; Lichtfield, P J; Longley, N P; Mann, W A; Marshak, M L; Milburn, R H; Miller, W H; Mualem, L M; Napier, A; Oliver, W P; Pearce, G F; Peterson, E A; Petyt, D A; Price, L E; Ruddick, K; Sánchez, M; Schneps, J; Schub, M H; Seidlein, R; Stassinakis, A; Thron, J L; Vasilev, V; Villaume, G; Wakely, S P; West, N; Wall, D

    1999-01-01

    The absorption of cosmic rays by the sun produces a shadow at the earth. The angular offset and broadening of the shadow are determined by the magnitude and structure of the interplanetary magnetic field (IPMF) in the inner solar system. We report the first measurement of the solar cosmic ray shadow by detection of deep underground muon flux in observations made during the entire ten-year interval 1989 to 1998. The sun shadow varies significantly during this time, with a $3.3\\sigma$ shadow observed during the years 1995 to 1998.

  13. Solar flare leaves sun quaking

    Science.gov (United States)

    1998-05-01

    Dr. Alexander G. Kosovichev, a senior research scientist from Stanford University, and Dr. Valentina V. Zharkova from Glasgow (United Kingdom) University found the tell-tale seismic signature in data on the Sun's surface collected by the Michelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO) spacecraft immediately following a moderate-sized flare on July 9, 1996. "Although the flare was a moderate one, it still released an immense amount of energy," said Dr. Craig Deforest, a researcher with the SOHO project. "The energy released is equal to completely covering the Earth's continents with a yard of dynamite and detonating it all at once." SOHO is a joint project of the European Space Agency and NASA. The finding is reported in the May 28 issue of the journal Nature, and is the subject of a press conference at the spring meeting of the American Geophysical Union in Boston, Mass., May 27. The solar quake that the science team recorded looks much like ripples spreading from a rock dropped into a pool of water. But over the course of an hour, the solar waves traveled for a distance equal to 10 Earth diameters before fading into the fiery background of the Sun's photosphere. Unlike water ripples that travel outward at a constant velocity, the solar waves accelerated from an initial speed of 22,000 miles per hour to a maximum of 250,000 miles per hour before disappearing. "People have looked for evidence of seismic waves from flares before, but they didn't have a theory so they didn't know where to look," says Kosovichev. Several years ago Kosovichev and Zharkova developed a theory that can explain how a flare, which explodes in space above the Sun's surface, can generate a major seismic wave in the Sun's interior. According to the currently accepted model of solar flares, the primary explosion creates high-energy electrons (electrically charged subatomic particles). These are funneled down into a magnetic flux tube, an invisible tube of magnetic

  14. Seismology of the Wounded Sun

    CERN Document Server

    Cally, Paul S

    2013-01-01

    Active regions are open wounds in the Sun's surface. Seismic oscillations from the interior pass through them into the atmosphere, changing their nature in the process to fast and slow magneto-acoustic waves. The fast waves then partially reflect and partially mode convert to upgoing and downgoing Alfv\\'en waves. The reflected fast and downgoing Alfv\\'en waves then re-enter the interior through the active regions that spawned them, infecting the surface seismology with signatures of the atmosphere. Using numerical simulations of waves in uniform magnetic fields, we calculate the upward acoustic and Alfv\\'enic losses in the atmosphere as functions of field inclination and wave orientation as well as the Time-Distance `travel time' perturbations, and show that they are related. Travel time perturbations relative to quiet Sun can exceed 40 seconds in 1 kG magnetic field. It is concluded that active region seismology is indeed significantly infected by waves leaving and re-entering the interior through magnetic w...

  15. The Sun's New Exotic Neighbour

    Science.gov (United States)

    2006-03-01

    Using ESO's Very Large Telescope in Chile, an international team of researchers [1] discovered a brown dwarf belonging to the 24th closest stellar system to the Sun. Brown dwarfs are intermediate objects that are neither stars nor planets. This object is the third closest brown dwarf to the Earth yet discovered, and one of the coolest, having a temperature of about 750 degrees Celsius. It orbits a very small star at about 4.5 times the mean distance between the Earth and the Sun. Its mass is estimated to be somewhere between 9 and 65 times the mass of Jupiter. At a time when astronomers are peering into the most distant Universe, looking at objects as far as 13 billion light-years away, one may think that our close neighbourhood would be very well known. Not so. Astronomers still find new star-like objects in our immediate vicinity. Using ESO's VLT, they just discovered a brown dwarf companion to the red star SCR 1845-6357, the 36th closest star to the Sun. ESO PR Photo 11/06 ESO PR Photo 11a/06 New Brown Dwarf in the Solar Neighbourhood (Artist's Impression) "This newly found brown dwarf is a valuable object because its distance is well known, allowing us to determine with precision its intrinsic brightness", said team member Markus Kasper (ESO). "Moreover, from its orbital motion, we should be able in a few years to estimate its mass. These properties are vital for understanding the nature of brown dwarfs." To discover this brown dwarf, the team used the high-contrast adaptive optics NACO Simultaneous Differential Imager (SDI [2]) on ESO's Very Large Telescope, an instrument specifically developed to search for extrasolar planets. The SDI camera enhances the ability of the VLT and its adaptive optics system to detect faint companions that would normally be lost in the glare of the primary star. In particular, the SDI camera provides additional, often very useful spectral information which can be used to determine a rough temperature for the object without follow

  16. Correlation of Spectral Solar Irradiance with solar activity as measured by VIRGO

    CERN Document Server

    Wehrli, C; Shapiro, A I

    2013-01-01

    Context. The variability of Solar Spectral Irradiance over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the SIM experiment on SORCE has published an unexpected negative correlation with Total Solar Irradiance of the visible spectral range. It is compensated by a strong and positive variability of the near UV range. Aims. We aim to verify whether the anti-correlated SIM/SORCE-trend in the visible can be confirmed by independent observations of the VIRGO experiment on SOHO. The challenge of all space experiments measuring solar irradiance are sensitivity changes of their sensors due to exposure to intense UV radiation, which are difficult to assess in orbit. Methods. We analyze a 10-year time series of VIRGO sun photometer data between 2002 and 2012. The variability of Spectral Solar Irradiance is correlated with the variability of the Total Solar Irradiance, which is...

  17. Gluing interface qualification test results and gluing process development of the EUCLID near-infrared spectro-photometer optical assembly

    Science.gov (United States)

    Mottaghibonab, A.; Thiele, H.; Gubbini, E.; Dubowy, M.; Gal, C.; Mecsaci, A.; Gawlik, K.; Vongehr, M.; Grupp, F.; Penka, D.; Wimmer, C.; Bender, R.

    2016-07-01

    The Near Infrared Spectro-Photometer Optical assembly (NIOA) of EUCLID satellite requires high precision large lens holders with different lens materials, shapes and diameters. The aspherical lenses are glued into their separate CTE matched lens holder. The gluing of the lenses in their holder with 2K epoxy is selected as bonding process to minimize the stress in the lenses to achieve the required surface form error (SFE) performance (32nm) and lens position stability (+/-10μm) due to glue shrinkage. Adhesive shrinkage stress occurs during the glue curing at room temperature and operation in cryogenic temperatures, which might overstress the lens, cause performance loss, lens breakage or failure of the gluing interface. The selection of the suitable glue and required bonding parameters, design and qualification of the gluing interface, development and verification of the gluing process was a great challenge because of the low TRL and heritage of the bonding technology. The different material combinations (CaF2 to SS316L, LF5G15 and S-FTM16 to Titanium, SUPRASIL3001 to Invar M93), large diameter (168mm) and thin edge of the lenses, cryogenic nonoperational temperature (100K) and high performance accuracy of the lenses were the main design driver of the development. The different coefficients of thermal expansion (CTE) between lens and lens holder produce large local mechanical stress. As hygroscopic crystal calcium fluoride (CaF2) is very sensitive to moisture therefore an additional surface treatment of the gluing area is necessary. Extensive tests e.g glue handling and single lap shear tests are performed to select the suitable adhesive. Interface connection tests are performed to verify the feasibility of selected design (double pad design), injection channel, the roughness and treatment of the metal and lens interfaces, glue thickness, glue pad diameter and the gluing process. CTE and dynamic measurements of the glue, thermal cycling, damp- heat, connection

  18. Accuracy assessment of water vapour measurements from in-situ and remote sensing techniques during the DEMEVAP 2011 campaign at OHP

    Directory of Open Access Journals (Sweden)

    O. Bock

    2013-04-01

    Full Text Available The Development of Methodologies for Water Vapour Measurement (DEMEVAP project aims at assessing and improving humidity sounding techniques and establishing a reference system based on the combination of Raman lidars, ground-based sensors and GPS. Such a system may be used for climate monitoring, radiosonde bias detection and correction, satellite measurement calibration/validation, and mm-level geodetic positioning with Global Navigation Satellite Systems. A field experiment was conducted in September–October 2011 at Observatoire de Haute Provence. Two Raman lidars, a stellar spectrometer (SOPHIE, a differential absorption spectrometer (SAOZ, a sun photometer (AERONET, 5 GPS receivers and 4 types of radiosondes (Vaisala RS92, MODEM M2K2-DC and M10, and Meteolabor Snow-White participated in the campaign. A total of 26 balloons with multiple radiosondes were flown during 16 clear nights. This paper presents preliminary findings from the analysis of all these datasets. Several classical Raman lidar calibration methods are evaluated which use either Vaisala RS92 measurements, point capacitive humidity measurements, or GPS integrated water vapour (IWV measurements. A novel method proposed by Bosser et al. (2010 is also tested. It consists in calibrating the lidar measurements during the GPS data processing. The methods achieve a repeatability of 4–5%. A drift in the IGN-LATMOS Raman lidar calibration of 15% over the 45 days of the experiment is evidenced but not yet explained. When this drift is removed, the precision of the calibration factors improves to 2–3%. However, the variations in the absolute calibration factor between methods and types of reference data remain at the level of 7%. The intercomparison of radiosonde measurements shows good agreement between RS92 and Snow-White measurements up to 12 km. An overall dry bias is found in the measurements from both MODEM radiosondes. Investigation of situations with low RH values (<10% in

  19. Here comes the sun...; Here comes the sun...

    Energy Technology Data Exchange (ETDEWEB)

    Best, Robert [Centro de Investigacion en Energia (CIE) de la UNAM, Temixco, Morelos (Mexico)

    2010-07-01

    It sounds a bit strange that you can use solar energy to maintain or refrigerate products or spaces below the ambient temperature, because we know that something that makes the sun is heating; but yes indeed, the sun can produce cold, and in addition without polluting, and without consuming conventional energy. In this document are mentioned the various research projects on solar cooling that have been made in the Energy Research Center at the Universidad Nacional Autonoma de Mexico such as the thermo-chemical intermittent refrigerator, the geothermal cooling demonstration system in Mexicali, B.C., the GAX system for air conditioning, the ice producer intermittent solar refrigerator, the continuous solar refrigerator, the refrigeration by ejection-compression. It also mentions the functioning of heat pumps and the process of solar drying applications in agricultural products. [Spanish] Suena un poco extrano que se pueda utilizar la energia solar para mantener o refrigerar productos o espacios por debajo de la temperatura ambiente, ya que sabemos que algo que hace el sol es calentar; pero si, el sol puede producir frio, y ademas sin contaminar y sin consumir energia convencional. En este documento se mencionan las diferentes investigaciones sobre refrigeracion solar que se han realizado en el Centro de Investigacion en Energia de la Universidad Nacional Autonoma de Mexico como el refrigerador termoquimico intermitente, el sistema demostrativo de refrigeracion geotermico en Mexicali, B.C., el sistema GAX para aire acondicionado, el refrigerador solar intermitente productor de hielo, el refrigerador continuo solar, la refrigeracion por eyecto-compresion. Tambien se menciona el funcionamiento de las bombas de calor y el proceso de secado solar de aplicacion en productos agropecuarios.

  20. The Eclipse of the Sun: Sun-dials, Clocks and Natural Time in the Late Seventeenth Century.

    Science.gov (United States)

    Turner, Anthony

    2015-01-01

    The Sun, in the early seventeenth century was, as it always had been, the ultimate arbiter of time-measurement In the last quarter of the century however this role was called into question as the new precision of post-Huygenian clocks revealed that natural time and the artificial mean time of the clock were not the same. Initially the question was little understood by the general public. The paper examines some early attempts to explain why "Sun-time" in 1700 was no longer "true-time."

  1. Interstellar Dust Close to the Sun

    CERN Document Server

    Frisch, Priscilla C

    2012-01-01

    The low density interstellar medium (ISM) close to the Sun and inside of the heliosphere provides a unique laboratory for studying interstellar dust grains. Grain characteristics in the nearby ISM are obtained from observations of interstellar gas and dust inside of the heliosphere and the interstellar gas towards nearby stars. Comparison between the gas composition and solar abundances suggests that grains are dominated by olivines and possibly some form of iron oxide. Measurements of the interstellar Ne/O ratio by the Interstellar Boundary Explorer spacecraft indicate that a high fraction of interstellar oxygen in the ISM must be depleted onto dust grains. Local interstellar abundances are consistent with grain destruction in ~150 km/s interstellar shocks, provided that the carbonaceous component is hydrogenated amorphous carbon and carbon abundances are correct. Variations in relative abundances of refractories in gas suggest variations in the history of grain destruction in nearby ISM. The large observed ...

  2. Imaging convection and magnetism in the sun

    CERN Document Server

    Hanasoge, Shravan

    2015-01-01

    This book reviews the field of helioseismology and its outstanding challenges and also offers a detailed discussion of the latest computational methodologies. The focus is on the development and implementation of techniques to create 3-D images of convection and magnetism in the solar interior and to introduce the latest computational and theoretical methods to the interested reader. With the increasing availability of computational resources, demand for greater accuracy in the interpretation of helioseismic measurements and the advent of billion-dollar instruments taking high-quality observations, computational methods of helioseismology that enable probing the 3-D structure of the Sun have increasingly become central. This book will benefit students and researchers with proficiency in basic numerical methods, differential equations and linear algebra who are interested in helioseismology.

  3. Choosing an expected sun protection factor value.

    Science.gov (United States)

    Sica, John R; Caswell, Michael

    2015-01-01

    Sun protection factor, SPF, is a measure of the efficacy of a topical sunscreen product; the higher the SPF, the greater the blockage of ultraviolet-induced erythema. While there are several methods to determine SPF, the Food and Drug Administration (FDA) methods are unique. The FDA methods define the label SPF value as the largest whole integer after subtracting an "A" value from the mean SPF. The A value, composed of the product of the upper 5% point of the t-distribution and the standard deviation (SD), divided by √(n), where n equals the number of subjects, has a significant impact on the label SPF value. Two examples explore this impact. Development of strategies to mitigate the impact of A using expected SPF values are explored using historical clinical trial data. A more enlightened choice of expected SPF values is shown to lead to higher label SPF values.

  4. Convectively driven vortex flows in the Sun

    CERN Document Server

    Bonet, J A; Almeida, J Sanchez; Cabello, I; Domingo, V

    2008-01-01

    We have discovered small whirlpools in the Sun, with a size similar to the terrestrial hurricanes (<~0.5 Mm). The theory of solar convection predicts them, but they had remained elusive so far. The vortex flows are created at the downdrafts where the plasma returns to the solar interior after cooling down, and we detect them because some magnetic bright points (BPs) follow a logarithmic spiral in their way to be engulfed by a downdraft. Our disk center observations show 0.009 vortexes per Mm^2, with a lifetime of the order of 5 min, and with no preferred sense of rotation. They are not evenly spread out over the surface, but they seem to trace the supergranulation and the mesogranulation. These observed properties are strongly biased by our type of measurement, unable to detect vortexes except when they are engulfing magnetic BPs.

  5. TRIGONOMETRIC SU(N) GAUDIN MODEL

    Institute of Scientific and Technical Information of China (English)

    曹俊鹏; 侯伯宇; 岳瑞宏

    2001-01-01

    In this paper, we obtain the eigenstates and the eigenvalues of the Hamiltonians of the trigonometric SU(N) Gaudin model based on the quasi-classical limit of the trigonometric SU(N) chain with the periodic boundary condition.By using the quantum inverse scattering method, we also obtain the eigenvalues of the generating function of the trigonometric SU(N) Gaudin model.

  6. The summer sun shone round me

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The summer sun shone round me, The folded valley lay In a stream of sun and odour, That sultry summer day. The tall trees stood in the sunlight As still as still could be, But the deep grass sighed and rustled And bowed and beckoned me. The deep grass moved and whispered And bowed and brushed my face. It whis pered in the sunshine: The winter comes apdce.”The summer sun shone round me

  7. Sun awareness in Maltese secondary school students.

    Science.gov (United States)

    Aquilina, S; Gauci, A Amato; Ellul, M; Scerri, L

    2004-11-01

    Studies indicate that reducing exposure to ultraviolet light during childhood and adolescence decreases the risk of skin cancer. From a young age, children need to be educated about the sun's harmful effects on the skin and how best to protect themselves. To help in the design of school-based interventions to raise sun awareness, a school survey was carried out to identify students' stereotypes and misconceptions. A total of 965 students attending Maltese secondary schools in forms 1, 2 and 3 were surveyed in May 2002, using a structured questionnaire designed to examine students' sun-related attitudes and knowledge. A high level of sun awareness among students was demonstrated, with high scores on knowledge of the effects of the sun on the skin, knowledge of skin cancer and knowledge of sun protection. Girls were clearly more knowledgeable than boys. However, of all the students surveyed, 55% thought that a suntan made them look better and 70% thought that their friends would desire a tan. These views were commoner among the older students. Skin type and hair or eye colour had no bearing on attitudes towards tanning or sun-related knowledge. The commonest misconceptions were that 'the sun is bad for your skin only when you get sunburnt' and that 'you cannot get too much sun on a cloudy day'. Deliberate suntanning was more frequently reported by girls than by boys and by students in the higher forms. Attitude change lags behind knowledge. Future school sun awareness interventions need to take into account gender and age differences in students' attitudes and perspectives. They should aim at motivating attitude change and preventive behaviour through consistent and repeated sun-education messages that are supported by a sun-conscious school environment.

  8. Sun Jingxia Devotes Herself to Nursing Work

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    "I really didn’t expect that at my advanced age, I would be awarded the highest honor in international nursing circles," said Mme. Sun Jingxia, 81, who had just returned from Beijing where she received the Nightingale Medal. Wearing a light yellow suit, with a collar bordered in red, Sun is inhigh spirits, reminding people of the beauty of the setting sun. It is clear that Sun Jingxia has deep feelings as she looks at the medal which shows a relief of Florence Nightingale’s head. She spoke in her usual soft voice but with some excitement, "President Jiang

  9. SOHO reveals violent action on the quiet Sun

    Science.gov (United States)

    1996-05-01

    rhythmic variations in the intensity of light or in its wavelength. The oscillations are caused by sound waves reverberating through the Sun. Just as seismology reveals the Earth's interior by studying earthquake waves, so helioseismology looks behind the Sun's enigmatic face. The helioseismologists of SOHO are delighted by their early results. They expected to benefit from a steady platform in space, where they can observe the Sun without interruption by clouds or sunsets, but what has gratified them is the clarity of the signals. Background noise previously blamed on the Sun turns out to have been due to the Earth's atmosphere. As a result SOHO gains a further advantage over ground-based stations. SOHO's oscillations imager MDI observes a million points on the Sun's visible surface once a minute. It can detect subtle, short-range oscillations due to sound waves penetrating only a short distance into the Sun. And it has generated the first chart of horizontal motions of gases just below the visible surface. "What pleases us is that shallow flows can be observed," says Philip Scherrer of Stanford University, California, who is principal investigator for MDI. "Ground-based instruments have detected motions deep inside the Sun. With SOHO we can do that too, but now we also provide the missing link to motions at the visible surface. Soon we shall make the first movies of the Sun's interior. And by relating what we see there to our measurements of surface magnetic fields we may begin to solve the mystery of why dark sunspots occur, and why they become most numerous every eleven years or so." Towards the solar maximum Observations at the present quiet phase of the solar cycle, when sunspots are scarce, provide an excellent baseline for later investigation of stormier and more confused conditions. These will occur around the year 2000 as the Sun enters its phase of maximum activity. Then the appearance of the Sun will change in SOHO's instruments, as the magnetic field contorts

  10. Investigation of Digital Sun Sensor Technology with an N-Shaped Slit Mask

    Directory of Open Access Journals (Sweden)

    Zheng You

    2011-10-01

    Full Text Available Nowadays sun sensors are being more widely used in satellites to determine the sunray orientation, thus development of a new version of sun sensor with lighter mass, lower power consumption and smaller size it of considerable interest. This paper introduces such a novel digital sun sensor, which is composed of a micro-electro-mechanical system (MEMS mask with an N-shaped slit as well as a single linear array charge-coupled device (CCD. The sun sensor can achieve the measurement of two-axis sunray angles according to the three sun spot images on the CCD formed by sun light illumination through the mask. Given the CCD glass layer, an iterative algorithm is established to correct the refraction error. Thus, system resolution, update rate and other characteristics are improved based on the model simulation and system design. The test of sun sensor prototype is carried out on a three-axis rotating platform with a sun simulator. The test results show that the field of view (FOV is ±60° × ±60° and the accuracy is 0.08 degrees of arc (3σ in the whole FOV. Since the power consumption of the prototype is only 300 mW and the update rate is 14 Hz, the novel digital sun sensor can be applied broadly in micro/nano-satellites, even pico-satellites.

  11. Validating MODIS above-cloud aerosol optical depth retrieved from "color ratio" algorithm using direct measurements made by NASA's airborne AATS and 4STAR sensors

    Science.gov (United States)

    Jethva, Hiren; Torres, Omar; Remer, Lorraine; Redemann, Jens; Livingston, John; Dunagan, Stephen; Shinozuka, Yohei; Kacenelenbogen, Meloe; Segal Rosenheimer, Michal; Spurr, Rob

    2016-10-01

    We present the validation analysis of above-cloud aerosol optical depth (ACAOD) retrieved from the "color ratio" method applied to MODIS cloudy-sky reflectance measurements using the limited direct measurements made by NASA's airborne Ames Airborne Tracking Sunphotometer (AATS) and Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) sensors. A thorough search of the airborne database collection revealed a total of five significant events in which an airborne sun photometer, coincident with the MODIS overpass, observed partially absorbing aerosols emitted from agricultural biomass burning, dust, and wildfires over a low-level cloud deck during SAFARI-2000, ACE-ASIA 2001, and SEAC4RS 2013 campaigns, respectively. The co-located satellite-airborne matchups revealed a good agreement (root-mean-square difference < 0.1), with most matchups falling within the estimated uncertainties associated the MODIS retrievals (about -10 to +50 %). The co-retrieved cloud optical depth was comparable to that of the MODIS operational cloud product for ACE-ASIA and SEAC4RS, however, higher by 30-50 % for the SAFARI-2000 case study. The reason for this discrepancy could be attributed to the distinct aerosol optical properties encountered during respective campaigns. A brief discussion on the sources of uncertainty in the satellite-based ACAOD retrieval and co-location procedure is presented. Field experiments dedicated to making direct measurements of aerosols above cloud are needed for the extensive validation of satellite-based retrievals.

  12. Validating MODIS Above-Cloud Aerosol Optical Depth Retrieved from Color Ratio Algorithm Using Direct Measurements Made by NASA's Airborne AATS and 4STAR Sensors

    Science.gov (United States)

    Jethva, Hiren; Torres, Omar; Remer, Lorraine; Redemann, Jens; Livingston, John; Dunagan, Stephen; Shinozuka, Yohei; Kacenelenbogen, Meloe; Segal Rozenhaimer, Michal; Spurr, Rob

    2016-01-01

    We present the validation analysis of above-cloud aerosol optical depth (ACAOD) retrieved from the color ratio method applied to MODIS cloudy-sky reflectance measurements using the limited direct measurements made by NASAs airborne Ames Airborne Tracking Sunphotometer (AATS) and Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) sensors. A thorough search of the airborne database collection revealed a total of five significant events in which an airborne sun photometer, coincident with the MODIS overpass, observed partially absorbing aerosols emitted from agricultural biomass burning, dust, and wildfires over a low-level cloud deck during SAFARI-2000, ACE-ASIA 2001, and SEAC4RS 2013 campaigns, respectively. The co-located satellite-airborne match ups revealed a good agreement (root-mean-square difference less than 0.1), with most match ups falling within the estimated uncertainties associated with the MODIS retrievals (about -10 to +50 ). The co-retrieved cloud optical depth was comparable to that of the MODIS operational cloud product for ACE-ASIA and SEAC4RS, however, higher by 30-50% for the SAFARI-2000 case study. The reason for this discrepancy could be attributed to the distinct aerosol optical properties encountered during respective campaigns. A brief discussion on the sources of uncertainty in the satellite-based ACAOD retrieval and co-location procedure is presented. Field experiments dedicated to making direct measurements of aerosols above cloud are needed for the extensive validation of satellite based retrievals.

  13. MuSun: muon capture on the deuteron

    Directory of Open Access Journals (Sweden)

    Luo Xiao

    2015-01-01

    Full Text Available The goal of the MuSun experiment at PSI is to measure the rate of muon capture on the deuteron with a precision of 1.5%. This rate will be used to fix the low-energy constant that describes the two-nucleon weak axial current in Chiral perturbation theory. It will therefore calibrate evaluations of solar proton-proton fusion and neutrino-deuteron scattering(SNO experiment. MuSun forms part of the systematic program to achieve a new level of precision in confronting the theories of weak interactions, QCD and few body physics. MuSun inherits some of the well developed techniques and apparatus from a successful measurement of the rate for muon capture on the proton, the MuCap experiment, also performed at PSI. As in MuCap, MuSun uses a TPC as an active target. To optimize the molecular kinetics, its ultra-pure deuterium gas is kept at 31K. The status of the hardware and details of the data analysis for a high statistics run taken in 2013 will be presented.

  14. ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Luhmann, Janet G.; Moestl, Christian; Bale, Stuart D.; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Lugaz, Noe [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Davies, Jackie A., E-mail: liuxying@ssl.berkeley.edu [Space Science and Technology Department, Rutherford Appleton Laboratory, Didcot (United Kingdom)

    2013-05-20

    We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts, and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of fast CMEs can be approximately formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a nearly constant speed propagation (or gradual deceleration); (2) the CMEs studied here are still accelerating even after the flare maximum, so energy must be continuously fed into the CME even after the time of the maximum heating and radiation has elapsed in the corona; (3) the rapid deceleration, presumably due to interactions with the ambient medium, mainly occurs over a relatively short timescale following the acceleration phase; and (4) CME-CME interactions seem a common phenomenon close to solar maximum. Our comparison between different techniques (and data sets) has important implications for CME observations and their interpretations: (1) for the current cases, triangulation assuming a compact CME geometry is more reliable than triangulation assuming a spherical front attached to the Sun for distances below 50-70 solar radii from the Sun, but beyond about 100 solar radii we would trust the latter more; (2) a proper treatment of CME geometry must be performed in determining CME Sun-to-Earth kinematics, especially when the CME propagation direction is far away from the

  15. Regina vs Hubbs: Determining the Sun's Position

    CERN Document Server

    Samra, Raminder Singh

    2012-01-01

    Here I determined the Sun's position as an expert witness for crown counsel. From my calculations I found the Sun's location in the sky was such that it could not impede the driver's vision, as a result it could not have been the reason for the accused to be involved in a motor vehicle accident.

  16. Mitochondrial DNA deletion percentage in sun exposed and non sun exposed skin.

    Science.gov (United States)

    Powers, Julia M; Murphy, Gillian; Ralph, Nikki; O'Gorman, Susan M; Murphy, James E J

    2016-12-01

    The percentages of mitochondrial genomes carrying the mtDNA(3895) and the mtDNA(4977) (common) deletion were quantified in sun exposed and non sun exposed skin biopsies, for five cohorts of patients varying either in sun exposure profile, age or skin cancer status. Non-melanoma skin cancer diagnoses are rising in Ireland and worldwide [12] but most risk prediction is based on subjective visual estimations of sun exposure history. A quantitative objective test for pre-neoplastic markers may result in better adherence to sun protective behaviours. Mitochondrial DNA (mtDNA) is known to be subject to the loss of a significant proportion of specific sections of genetic code due to exposure to ultraviolet light in sunlight. Although one such deletion has been deemed more sensitive, another, called the mtDNA(4977) or common deletion, has proved to be a more useful indicator of possible risk in this study. Quantitative molecular analysis was carried out to determine the percentage of genomes carrying the deletion using non sun exposed and sun exposed skin biopsies in cohorts of patients with high or low sun exposure profiles and two high exposure groups undergoing treatment for NMSC. Results indicate that mtDNA deletions correlate to sun exposure; in groups with high sun exposure habits a significant increase in deletion number in exposed over non sun exposed skin occurred. An increase in deletion percentage was also seen in older cohorts compared to the younger group. The mtDNA(3895) deletion was detected in small amounts in exposed skin of many patients, the mtDNA(4977) common deletion, although present to some extent in non sun exposed skin, is suggested to be the more reliable and easily detected marker. In all cohorts except the younger group with relatively lower sun exposure, the mtDNA(4977) deletion was more frequent in sun exposed skin samples compared to non-sun exposed skin.

  17. SOHO starts a revolution in the science of the Sun

    Science.gov (United States)

    1996-07-01

    Point No. 1 where the gravity of the Sun and the Earth are in balance. The spacecraft's engineering has proved to be excellent and no difficulty is anticipated in keeping it operational for at least six years. Early SOHO results were summarized in ESA's Information Note Nr 07-96, 2 May 1996. Here follow notes and comments on some further conclusions by SOHO's scientists. Fast action in the Sun's atmosphere The ultraviolet spectrometers aboard SOHO, called SUMER and CDS, were designed to analyse events in the solar atmosphere and discover temperatures, densities and speeds of motion in the gas. Their detailed results come in the spectra, which analyse the intensities at different wavelengths with high sensitivity, but the spectrometers also generate images by scanning selected regions of the Sun. When the SUMER instrument scans the whole Sun by the ultraviolet light of strongly ionized sulphur atoms (S VI at 933 angstroms) it picks out gas at 200,000 degrees C and reveals a vast number of bright regions created by magnetic field lines looping through the atmosphere. The brightness can change by a factor of ten in a distance of a few thousand kilometres or in a few seconds of time. SUMER has also shown that thick streaks called polar plumes, which climb far into space from the Sun's polar regions, are anchored in bright regions near the Sun's visible surface. The spectrometer CDS has observed fast action in the Sun's atmosphere. It can measure velocities along the line of sight by shifts in the wavelength of emissions from selected atoms, and contrary motions (turbulence) appear in a spreading of the wavelengths. In one high-velocity event, corresponding with a small streak of brightness in the scanned image, CDS detected vertical motions differing by 450 kilometres per second, and an overall motion of 65 kilometres per second downwards. "By taking the Sun's atmosphere to pieces we begin to understand how it influences our lives," says Richard Harrison of the UK

  18. Gravitational Lensing Characteristics of the Transparent Sun

    CERN Document Server

    Patla, Bijunath

    2007-01-01

    The transparent Sun is modeled as a spherically symmetric and centrally condensed gravitational lens using recent Standard Solar Model (SSM) data. The Sun's minimum focal length is computed to a refined accuracy of 23.5 +/- 0.1 AU, just beyond the orbit of Uranus. The Sun creates a single image of a distant point source visible to observers inside this minimum focal length and to observers sufficiently removed from the line connecting the source through the Sun's center. Regions of space are mapped where three images of a distant point source are created, along with their associated magnifications. Solar caustics, critical curves, and Einstein rings are computed and discussed. Extremely high gravitational lens magnifications exist for observers situated so that an angularly small, unlensed source appears near a three-image caustic. Types of radiations that might undergo significant solar lens magnifications as they can traverse the core of the Sun, including neutrinos and gravitational radiation, are discusse...

  19. Vibration Based Sun Gear Damage Detection

    Science.gov (United States)

    Hood, Adrian; LaBerge, Kelsen; Lewicki, David; Pines, Darryll

    2013-01-01

    Seeded fault experiments were conducted on the planetary stage of an OH-58C helicopter transmission. Two vibration based methods are discussed that isolate the dynamics of the sun gear from that of the planet gears, bearings, input spiral bevel stage, and other components in and around the gearbox. Three damaged sun gears: two spalled and one cracked, serve as the focus of this current work. A non-sequential vibration separation algorithm was developed and the resulting signals analyzed. The second method uses only the time synchronously averaged data but takes advantage of the signal/source mapping required for vibration separation. Both algorithms were successful in identifying the spall damage. Sun gear damage was confirmed by the presence of sun mesh groups. The sun tooth crack condition was inconclusive.

  20. The relationship between luminosity of sprite halo and charge moment change based on ISUAL and ELF measurements

    Science.gov (United States)

    Nakajo, Hiroshi; Takahashi, Yukihiro; Hiromi, Kase; Adachi, Toru; Sato, Mitsuteru; Yamashita, Kozo

    Sprite is a transient luminous phenomenon in the mesosphere, induced by lightning discharges. We have known the facts that there are some varieties of features, such as sprite-streamers with fine-structures and sprite-halos with pancake-structures. However, due to the atmospheric ab-sorption and scattering, it is difficult to discuss its luminous intensity quantitatively. After 2004, the beginning of optical observations with ISUAL/FORMOSAT-2 from space, the abso-lute luminosity of sprite became to be discussed. There is a compelling theory which predicts that sprite occurrence is dependent on the quasi-electrostatic field induced by lightning. In such a case, it is speculated that the intensity of the sprite emission should have a relationship to the charge moment of the parent lightning because the strength of the electric field is propor-tional to the charge moment of lightning. By Yoshida (2007), absolute optical energies emitted from sprites were estimated for 14 streamer type sprites, using ISUAL/Array photometer data. Furthermore, the optical energies of the streamer type sprites and the charge moments of their parent lightning estimated by ELF data show high correlation (correlation coefficient = 0.93). However, the relationship between the optical energies of sprite-halos and the charge moments of their parent lightning is still unknown. In this study, we analyze 12 sprite-halos, using ISUAL/Array photometer data and ELF data from July 2004 to October 2005. The ISUAL in-strument on board the FORMOSAT-2 satellite, which flies on a sun-synchronous (9:30 to 21:30 local time) polar-orbit at an altitude of 891 km, consists of an imager, a spectrophotometer (SP), and an array photometer (AP). It looks at the limb in the midnight direction. The AP consists of two multi-channel photometers simultaneously measuring two different wavelength ranges of 510-750 nm (N2 1PG) and 340-480 nm (N2 2PG) with blue and red filters, respec-tively. Each photometer has sixteen

  1. Could Ultracool Dwarfs Have Sun-Like Activity?

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    emission primarily polarized in a single direction. The dwarfs flares in late 2013, however, all showed polarization in the opposite direction. Could this be an indication that J1047+21 has a stable, global dipolar field that flipped polarity in between the two sets of observations? If so, this could mean that the star has a magnetic cycle similar to the Suns.Artists impression showing the relative sizes and colors of the Sun, a red dwarf (M-dwarf), a hotter brown dwarf (L-dwarf), a cool brown dwarf (T-dwarf) similar to J1047+21, and the planet Jupiter [Credit: NASA/IPAC/R. Hurt (SSC)]Inspired by this possibility, Route conducted an investigation of the long-term magnetic behavior of all known radio-flaring ultracool dwarfs, a list of 14 stars. Using polarized radio emission measurements, he found that many of his targets exhibited similar polarity flips, which he argues is evidence that these dwarfs are undergoing magnetic field reversals on roughly decade-long timescales, analogous to those reversals that occur in the Sun.If this is indeed true, then we need to examine our models of how magnetic fields are generated in stars: the interface between the radiative and convective layers may not be necessary to produce large-scale magnetic fields. Understanding this process is certainly an important step in interpreting the potential habitability of planets around ultracool dwarfs.CitationMatthew Route 2016 ApJL 830 L27. doi:10.3847/2041-8205/830/2/L27

  2. Retrieval of aerosol backscatter and extinction from airborne coherent Doppler wind lidar measurements

    Directory of Open Access Journals (Sweden)

    F. Chouza

    2015-02-01

    Full Text Available A novel method for calibration and quantitative aerosol optical properties retrieval from Doppler wind lidars (DWL is presented in this work. Due to the strong wavelength dependence of the atmospheric molecular backscatter and the low sensitivity of the coherent detection to spectrally broad signals, calibration methods for aerosol lidars cannot be applied to a coherent DWLs usually operating at wavelengths between 1.5–2 μm. Instead, concurrent measurements of an airborne DWL at 2 μm and the POLIS ground-based aerosol lidar at 532 nm are used in this work, in combination with sun photometer measurements, for the calibration and retrieval of aerosol backscatter and extinction profiles. The proposed method was applied to measurements from the SALTRACE experiment in June–July 2013, which aimed at quantifying the aerosol transport and change in aerosol properties from the Sahara desert to the Caribbean. The retrieved backscatter and extinction coefficient profiles from the airborne DWL are within 20% of POLIS aerosol lidar and CALIPSO satellite measurements. Thus the proposed method extends the capabilities of coherent DWL to measure profiles of the horizontal and vertical wind towards aerosol backscatter and extinction profiles, which is of high benefit for aerosol transport studies.

  3. Real-Time Projection Shadow with Respect to Sun Position in Virtual Environments

    Directory of Open Access Journals (Sweden)

    Hoshang Kolivand

    2011-11-01

    Full Text Available This paper proposes a real-time software for outdoor rendering to control the shadows position with effect of sun's position. The position of sun plays an important rule for outdoor games. Calculation of sun's position, as a result, position and length of shadows require a lot of attention and preciseness. Julian dating is used to calculate the sun's position in the virtual dome. In addition, of computer graphics, building design is another field that this paper contributes on it. To create shadow, projection shadow is proposed. By calculating the sun's position in the specific date, time and location on the earth, shadow is generated. Length and angle of shadow are two parameters measured for building design and both of them are calculated in this real-time application. Therefore, it can be used for teachers to teach some part of physics about earth orbit and it can be used in building design and commercial games in virtual reality systems.

  4. 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....

  5. The Sun and How to Observe It

    CERN Document Server

    Jenkins, Jamey L

    2009-01-01

    Without the Sun, all life on Earth would perish. But what exactly do we know about this star that lights, heats, and powers Earth? Actually, we know quite a lot, thanks mainly to a host of eager solar observers. Looking directly at the Sun is EXTREMELY hazardous. But many astronomers, both professional and amateur, have found ways to view the Sun safely to learn about it. You, too, can view the Sun in all of its glorious detail. Some of the newest, most exciting telescopes on the market are affordable to amateur astronomers or even just curious sky watchers, and with this guide to what the Sun has to offer, including sunspots, prominences, and flares, plus reviews of the latest instruments for seeing and capturing images of the Sun, you can contribute to humankind’s knowledge of this immense ball of glowing gases that gives us all life. For a complete guide to Sun viewing, see also Total Solar Eclipses and How to Observe Them (2007) by Martin Mobberley in this same series.

  6. Sun-synchronous satellite orbit determination

    Science.gov (United States)

    Ma, Der-Ming; Zhai, Shen-You

    2004-02-01

    The linearized dynamic equations used for on-board orbit determination of Sun-synchronous satellite are derived. Sun-synchronous orbits are orbits with the secular rate of the right ascension of the ascending node equal to the right ascension rate of the mean sun. Therefore the orbit is no more a closed circle but a tight helix about the Earth. In the paper, instead of treating the orbit as a closed circle, the actual helix orbit is taken as nominal trajectory. The details of the linearized equations of motion for the satellite in the Sun-synchronous orbit are derived. The linearized equations are obtained by perturbing the Keplerian motion with the J2 correction and the effect of sun's attraction being neglected. Combined with the GPS navigation equations, the Kalman filter formulation is given. The particular application considered is the circular Sun-synchronous orbit with the altitude of 800 km and inclination of 98.6°. The numerical example simulated by MATLAB® shows that only the pseudo-range data used in the algorithm still gives acceptable results. Based on the simulation results, we can use the on-board GPS receivers' signal only as an alternative to determine the orbit of Sun-Synchronous satellite and therefore circumvents the need for extensive ground support.

  7. SunPy—Python for solar physics

    Science.gov (United States)

    SunPy Community; Mumford, Stuart J.; Christe, Steven; Pérez-Suárez, David; Ireland, Jack; Shih, Albert Y.; Inglis, Andrew R.; Liedtke, Simon; Hewett, Russell J.; Mayer, Florian; Hughitt, Keith; Freij, Nabil; Meszaros, Tomas; Bennett, Samuel M.; Malocha, Michael; Evans, John; Agrawal, Ankit; Leonard, Andrew J.; Robitaille, Thomas P.; Mampaey, Benjamin; Campos-Rozo, Jose Iván; Kirk, Michael S.

    2015-01-01

    This paper presents SunPy (version 0.5), a community-developed Python package for solar physics. Python, a free, cross-platform, general-purpose, high-level programming language, has seen widespread adoption among the scientific community, resulting in the availability of a large number of software packages, from numerical computation (NumPy, SciPy) and machine learning (scikit-learn) to visualization and plotting (matplotlib). SunPy is a data-analysis environment specializing in providing the software necessary to analyse solar and heliospheric data in Python. SunPy is open-source software (BSD licence) and has an open and transparent development workflow that anyone can contribute to. SunPy provides access to solar data through integration with the Virtual Solar Observatory (VSO), the Heliophysics Event Knowledgebase (HEK), and the HELiophysics Integrated Observatory (HELIO) webservices. It currently supports image data from major solar missions (e.g., SDO, SOHO, STEREO, and IRIS), time-series data from missions such as GOES, SDO/EVE, and PROBA2/LYRA, and radio spectra from e-Callisto and STEREO/SWAVES. We describe SunPy's functionality, provide examples of solar data analysis in SunPy, and show how Python-based solar data-analysis can leverage the many existing tools already available in Python. We discuss the future goals of the project and encourage interested users to become involved in the planning and development of SunPy.

  8. Sun Basking in Red Wood Ants Formica polyctena (Hymenoptera, Formicidae): Individual Behaviour and Temperature-Dependent Respiration Rates.

    Science.gov (United States)

    Kadochová, Štěpánka; Frouz, Jan; Roces, Flavio

    2017-01-01

    In early spring, red wood ants Formica polyctena are often observed clustering on the nest surface in large numbers basking in the sun. It has been hypothesized that sun-basking behaviour may contribute to nest heating because of both heat carriage into the nest by sun-basking workers, and catabolic heat production from the mobilization of the workers' lipid reserves. We investigated sun-basking behaviour in laboratory colonies of F. polyctena exposed to an artificial heat source. Observations on identified individuals revealed that not all ants bask in the sun. Sun-basking and non-sun-basking workers did not differ in body size nor in respiration rates. The number of sun-basking ants and the number of their visits to the hot spot depended on the temperature of both the air and the hot spot. To investigate whether sun basking leads to a physiological activation linked with increased lipolysis, we measured respiration rates of individual workers as a function of temperature, and compared respiration rates of sun-basking workers before and two days after they were allowed to expose themselves to a heat source over 10 days, at self-determined intervals. As expected for ectothermic animals, respiration rates increased with increasing temperatures in the range 5 to 35°C. However, the respiration rates of sun-basking workers measured two days after a long-term exposure to the heat source were similar to those before sun basking, providing no evidence for a sustained increase of the basal metabolic rates after prolonged sun basking. Based on our measurements, we argue that self-heating of the nest mound in early spring has therefore to rely on alternative heat sources, and speculate that physical transport of heat in the ant bodies may have a significant effect.

  9. Sun Basking in Red Wood Ants Formica polyctena (Hymenoptera, Formicidae): Individual Behaviour and Temperature-Dependent Respiration Rates

    Science.gov (United States)

    Kadochová, Štěpánka; Frouz, Jan; Roces, Flavio

    2017-01-01

    In early spring, red wood ants Formica polyctena are often observed clustering on the nest surface in large numbers basking in the sun. It has been hypothesized that sun-basking behaviour may contribute to nest heating because of both heat carriage into the nest by sun-basking workers, and catabolic heat production from the mobilization of the workers’ lipid reserves. We investigated sun-basking behaviour in laboratory colonies of F. polyctena exposed to an artificial heat source. Observations on identified individuals revealed that not all ants bask in the sun. Sun-basking and non-sun-basking workers did not differ in body size nor in respiration rates. The number of sun-basking ants and the number of their visits to the hot spot depended on the temperature of both the air and the hot spot. To investigate whether sun basking leads to a physiological activation linked with increased lipolysis, we measured respiration rates of individual workers as a function of temperature, and compared respiration rates of sun-basking workers before and two days after they were allowed to expose themselves to a heat source over 10 days, at self-determined intervals. As expected for ectothermic animals, respiration rates increased with increasing temperatures in the range 5 to 35°C. However, the respiration rates of sun-basking workers measured two days after a long-term exposure to the heat source were similar to those before sun basking, providing no evidence for a sustained increase of the basal metabolic rates after prolonged sun basking. Based on our measurements, we argue that self-heating of the nest mound in early spring has therefore to rely on alternative heat sources, and speculate that physical transport of heat in the ant bodies may have a significant effect. PMID:28114396

  10. Field measurement of clear-sky solar irradiance in Badain Jaran Desert of Northwestern China

    Science.gov (United States)

    Bi, Jianrong; Huang, Jianping; Fu, Qiang; Ge, Jinming; Shi, Jinsen; Zhou, Tian; Zhang, Wu

    2013-06-01

    The Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) sponsored and conducted an intensive field campaign on dust aerosols in Badain Jaran Desert of Northwestern China from April 20 to June 20, 2010. A set of state-of-the-art broadband radiometers and sun/sky photometers were deployed along with launched radiosonde. In this paper, we compared the simulated solar irradiances by using the SBDART radiative transfer model with those from the ground-based measurements for 69 selected cases of 7 days. It was shown that the averaged aerosol optical depth at 500nm (AOD500) is 0.18±0.09 with AOD500 less than 0.5 for all cases. The single-scattering albedo and asymmetry factor at 675nm are 0.928±0.035, 0.712±0.023, respectively. The AODs retrieved from the CIMEL sun photometer at various wavelengths agree well with those from the PREDE sky radiometer, and the columnar water vapor contents from CIMEL also agree well with radiosonde observations. In the radiative closure experiment, we used a collocated thermopile pyrgeometer with a shadow and ventilator to correct the thermal dome offset of diffuse irradiance measurement. The mean differences between model and measurements are -9.1Wm-2 (-2.6%) for the direct irradiance, +3.1Wm-2 (+2.8%) for diffuse irradiance, and -6.0Wm-2 (-1.3%) for global irradiance, which indicates an excellent radiative closure. Aerosol shortwave direct radiative forcing (ARF) and radiative heating rate are also investigated. The daily mean ARF ranges from -4.8 to +0.4Wm-2 at the top of the atmosphere, -5.2 to -15.6Wm-2 at the surface, and 5.2 to 10.8Wm-2 in the atmosphere. The corresponding radiative heating rates for the whole atmosphere due to dust aerosols are 0.07, 0.11, 0.14, 0.11, 0.10, 0.08, and 0.07K/day for the 7 selected cloudless days. These solar radiative forcing can be considered as the representative impact of background dust aerosol in Northwestern China.

  11. EffeCts of Direct sUn Drying of Maize Grains on Perforated and ...

    African Journals Online (AJOL)

    Abstract. Sun drying ofmqize grains on unperforated and perforatedsurfaceswas ... and 40 mm in the field The response variables measured were weight loss at all depths and moisture con- ..... tent (on milled grains and on whole grains): The.

  12. Semiautomatic sun shots with the WIDIF DIflux

    Science.gov (United States)

    Rasson, Jean L.; Hendrickx, Olivier; Marin, Jean-Luc

    2017-07-01

    The determination of magnetic declination angle entails finding two directions: geographic north and magnetic north. This paper deals with the former. The known way to do it by using the sun's calculable orientation in the sky is improved by using a device based on a WIDIF DIflux theodolite and split photocells positioned on its telescope ocular. Given the WIDIF accurate timing and location provided by the onboard GPS receiver, an astronomical computation can be effected to accurately and quickly determine the sun's azimuth and an auxiliary mark's azimuth. The precise sun's crossing of the split photocell, amplified by the telescope's magnification, allows azimuth accuracies of a few seconds of arc.

  13. First results of measurements of extreme ultraviolet radiation onboard a geostationary satellite "ELECTRO-L"

    Science.gov (United States)

    Nusinov, Anatoliy; Kazachevskaya, Tamara; Gonjukh, David

    Measurements of the intensity of EUV emission in the hydrogen Lyman-alpha line were conducted by a broadband photometer VUSS-E onboard geostationary Hydrometeorological satellite "Electro" since March 2011. The solar hydrogen Lyman-alpha line (lambda = 121.6 nm) was monitored. The photomultiplier with LiF window used as a detector insensitive to visible light. Long-wavelength limit of the spectral band sensitivity of the instrument is about 200 nm, so the signal of the device is defined as the flux of solar radiation in the region of 123-200 nm. Its exclusion was carried out by calculation. Since the satellite "Electro" designed for remote sensing of the Earth, its line of sight focused on Earth. Alignment of instrument in the Sun direction was achieved by installing it on the solar panel, periodically moved in the solar direction. Correction of instrument readings, reduced due to the deviation of its axis from the Sun direction, carried out by calculation. Measurements were carried out every second. The first results of the measurements are presented. The difference in absolute calibration Electro-L/VUSS-E is within 5% of corresponding values for measurements TIMED satellite in those days, that is in agreement with laboratory calibrations. It is useful to measure the temperature of the instrument, as its variation on a small interval of time makes change the value of the output signal about 1-2 %. During first year of operation, the sensitivity of the apparatus remained within ± 2% of measured value, significant degradation of sensitivity was not observed. Over time of observation there have been several large flares of X class. The increase of the signal in the ultraviolet range does not exceed a few percent during these flares.

  14. Long term aerosol and trace gas measurements in Central Amazonia

    Science.gov (United States)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

    2016-04-01

    The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

  15. Recent Progress in Understanding the Sun's Magnetic Dynamo

    Science.gov (United States)

    Hathaway, David. H.

    2004-01-01

    100 years ago we thought that the Sun and stars shone as a result of slow gravitational contraction over a few tens of millions of years - putting astronomers at odds with geologists who claimed that the Earth was much, much older. That mystery was solved in the 1920s and 30s with the discovery of nuclear energy (proving that the geologists had it right all along). Other scientific mysteries concerning the Sun have come and gone but three major mysteries remain: 1) How does the Sun produce sunspots with an 11-year cycle? 2) What produces the huge explosions that result in solar flares, prominence eruptions, and coronal mass ejections? and 3) Why is the Sun's outer atmosphere, the corona, so darned hot? Recent progress in solar astronomy reveals a single key to understanding all three of these mysteries.The 11-year time scale for the sunspot cycle indicates the presence of a magnetic dynamo within the Sun. For decades this dynamo was though to operate within the Sun's convection zone - the outmost 30% of the Sun where convective currents transport heat and advect magnetic lines of force. The two leading theories for the dynamo had very different models for the dynamics of the convection zone. Actual measurements of the dynamics using the techniques of helioseismology showed that both of these models had to be wrong some 20 years ago. A thin layer of strongly sheared flow at the base of the convection zone (now called the tachocline) was then taken to be the seat of the dynamo. Over the last 10 years it has become apparent that a weak meridional circulation within the convection zone also plays a key role in the dynamo. This meridional circulation has plasma rising up from the tachocline in the equatorial regions, spreading out toward the poles at a top speed of about 10-20 m/s at the surface, sinking back down to the tachocline in the polar regions, and then flowing back toward the equator at a top speed of about 1-2 m/s in the tachocline itself. Recent dynamo

  16. Recent Progress in Understanding the Sun's Magnetic Dynamo

    Science.gov (United States)

    Hathaway, David. H.

    2004-01-01

    100 years ago we thought that the Sun and stars shone as a result of slow gravitational contraction over a few tens of millions of years - putting astronomers at odds with geologists who claimed that the Earth was much, much older. That mystery was solved in the 1920s and 30s with the discovery of nuclear energy (proving that the geologists had it right all along). Other scientific mysteries concerning the Sun have come and gone but three major mysteries remain: 1) How does the Sun produce sunspots with an 11-year cycle? 2) What produces the huge explosions that result in solar flares, prominence eruptions, and coronal mass ejections? and 3) Why is the Sun's outer atmosphere, the corona, so darned hot? Recent progress in solar astronomy reveals a single key to understanding all three of these mysteries.The 11-year time scale for the sunspot cycle indicates the presence of a magnetic dynamo within the Sun. For decades this dynamo was though to operate within the Sun's convection zone - the outmost 30% of the Sun where convective currents transport heat and advect magnetic lines of force. The two leading theories for the dynamo had very different models for the dynamics of the convection zone. Actual measurements of the dynamics using the techniques of helioseismology showed that both of these models had to be wrong some 20 years ago. A thin layer of strongly sheared flow at the base of the convection zone (now called the tachocline) was then taken to be the seat of the dynamo. Over the last 10 years it has become apparent that a weak meridional circulation within the convection zone also plays a key role in the dynamo. This meridional circulation has plasma rising up from the tachocline in the equatorial regions, spreading out toward the poles at a top speed of about 10-20 m/s at the surface, sinking back down to the tachocline in the polar regions, and then flowing back toward the equator at a top speed of about 1-2 m/s in the tachocline itself. Recent dynamo

  17. A Physical Model of Phaethon, a Near-Sun Object

    Science.gov (United States)

    Boice, Daniel C.; Benkhoff, J.; Huebner, W. F.

    2013-10-01

    Physico-chemical modeling is central to understand the important physical processes that occur in small solar system bodies. We have developed a computer code, SUSEI, that includes the physico-chemical processes relevant to comets within a global modeling framework to better understand observations and in situ measurements and to provide valuable insights into the intrinsic properties of their nuclei. SUISEI includes a 3D model of gas and heat transport in porous sub-surface layers in the interior of the nucleus. We have successfully used this model in our study of previous comets at normal heliocentric distances [e.g., 46P/Wirtanen, D/1993 F2 (Shoemaker-Levy 9)]. We have adapted SUISEI to model near-Sun objects to reveal significant differences in the chemistry and dynamics of their comae (atmosphere) with comets that don’t closely approach the Sun. At small heliocentric distances, temperatures are high enough to vaporize surface materials and dust, forming a source of gas. Another important question concerns the energy balance at the body’s surface, namely what fraction of incident energy will be conducted into the interior versus that used for sublimation. This is important to understand if the interior stays cold and is relatively unaltered during each perihelion passage or is significantly devolatilized. This also bears upon the regimes where sublimation and ablation due to ram pressure dominate in the erosion or eventual destruction of sun-grazers. The resulting model will be an important tool for studying sungrazing comets and other near-Sun objects. We will present results on the application of SUISEI to the near-Sun object, Phaethon. Acknowledgements: We appreciate support from the SwRI IR&D and the NSF Planetary Astronomy Programs.

  18. Estimation of surface insolation using sun-synchronous satellite data

    Science.gov (United States)

    Darnell, Wayne L.; Staylor, W. Frank; Gupta, Shashi K.; Denn, Fred M.

    1988-01-01

    A technique is presented for estimating insolation at the earth's surface using only sun-synchronous satellite data. The technique was tested by comparing the insolation results from year-long satellite data sets with simultaneous ground-measured insolation taken at five continental United States sites. Monthly average insolation values derived from the satellite data showed a standard error of 4.2 W/sq m, or 2.7 percent of the average ground insolation value.

  19. Finding the lost siblings of the Sun

    Science.gov (United States)

    Liu, Cheng; Feltzing, Sofia; Ruchti, Gregory

    2014-01-01

    We have performed a spectral analysis on 18 stars solar sibling candidate. We found that only one one of the candidateshas solar metallicity and at the same time might have an age comparable to that of the Sun.

  20. Sun and Other Types of Radiation

    Science.gov (United States)

    ... What Causes Cancer? Sun and Other Types of Radiation Learn about the different types of radiation and ... other diseases. Learn more here. Other Types of Radiation Exposure Not all types of radiation have been ...

  1. UV Photography Shows Hidden Sun Damage

    Science.gov (United States)

    ... mcat1=de12", ]; for (var c = 0; c UV photography shows hidden sun damage A UV photograph gives ... developing skin cancer and prematurely aged skin. Normal photography UV photography 18 months of age: This boy's ...

  2. Nilaja Sun's "No Child...": Reflections on Success

    Science.gov (United States)

    Sun, Nilaja; Alexander, Phillip; Huldeen, Branden; Russell, Ron; Friedman, Melissa

    2007-01-01

    This article describes Nilaja Sun's groundbreaking one-woman show about a TA, her students, and her school, and includes interviews with the author/performer, an excerpt of the work, and a discussion of the organization behind it.

  3. The Sun murrab Baltimaadesse ja Soome

    Index Scriptorium Estoniae

    2008-01-01

    Aprillis andis ansambel Tanel Padar & The Sun Soomes, Lätis, Leedus ja Eestis üksteist kontserti. Heliplaadi "Here Gomes The Sun" lugu "Hopelessness You" on Soome raadiote tipp 300s neljakümnendal kohal, lugu "Learn the game" on Leedu FM99 raadios 33 enim mängitava loo seas, laul "One of those days" saavutas Läti raadio SWH rokkmuusika edetabelis teise koha.

  4. Optimal control of sun tracking solar concentrators

    Science.gov (United States)

    Hughes, R. O.

    1979-01-01

    Application of the modern control theory to derive an optimal sun tracking control for a point focusing solar concentrator is presented. A standard tracking problem converted to regulator problem using a sun rate input achieves an almost zero steady state tracking error with the optimal control formulation. However, these control techniques are costly because optimal type algorithms require large computing systems, thus they will be used mainly as comparison standards for other types of control algorithms and help in their development.

  5. The Sun murrab Baltimaadesse ja Soome

    Index Scriptorium Estoniae

    2008-01-01

    Aprillis andis ansambel Tanel Padar & The Sun Soomes, Lätis, Leedus ja Eestis üksteist kontserti. Heliplaadi "Here Gomes The Sun" lugu "Hopelessness You" on Soome raadiote tipp 300s neljakümnendal kohal, lugu "Learn the game" on Leedu FM99 raadios 33 enim mängitava loo seas, laul "One of those days" saavutas Läti raadio SWH rokkmuusika edetabelis teise koha.

  6. Orientation in birds. The sun compass.

    Science.gov (United States)

    Schmidt-Koenig, K; Ganzhorn, J U; Ranvaud, R

    1991-01-01

    The sun compass was discovered by G. Kramer in caged birds showing migratory restlessness. Subsequent experiments with caged birds employing directional training and clock shifts, carried out by Hoffman and Schmidt-Koenig, showed that the sun azimuth is used, and the sun altitude ignored. In the laboratory, McDonald found the accuracy to be +/- 3 degrees(-)+/- 5 degrees. According to Hoffmann and Schmidt-Koenig, caged birds trained at medium northern latitudes were able to allow for the sun's apparent movement north of the arctic circle, but not in equatorial and trans-equatorial latitudes. In homing experiments, and employing clock shifts, Schmidt-Koenig demonstrated that the sun compass is used by homing pigeons during initial orientation. This finding is the principal evidence for the existence of a map-and-compass navigational system. Pigeons living in equatorial latitudes utilize the sun compass even under the extreme solar conditions of equinox, achieving angular resolution of about 3 degrees in homing experiments. According to preliminary analyses, the homing pigeons' ephemerides are retarded by several weeks (Ranvaud, Schmidt-Koenig, Ganzhorn et al.).

  7. SunPy: Solar Physics in Python

    Science.gov (United States)

    Ryan, Daniel; Christe, Steven; Mumford, Stuart; Perez Suarez, David; Ireland, Jack; Shih, Albert Y.; Inglis, Andrew; Liedtke, Simon; Hewett, Russel

    2015-04-01

    SunPy is a community-developed open-source software library for solar physics. It is written in Python, a free, cross-platform, general-purpose, high-level programming language which is being increasingly adopted throughout the scientific community as well as further afield. This has resulted in a wide array of software packages useful for scientific computing, from numerical computation (NumPy, SciPy, etc.), to machine learning (scifitlearn), to visualization and plotting (matplotlib). SunPy aims to provide required specialised software for analysing solar and heliospheric datasets in Python. The current version is 0.5 with 0.6 expected to be released later this year. SunPy provides solar data access through integration with the Virtual Solar Observatory (VSO), the Heliophysics Event Knowledgebase (HEK), and the HELiophysics Integrated Observatory (HELIO) webservices. It supports common data types from major solar missions such as images (SDO/AIA, STEREO, PROBA2/SWAP etc.), time series (GOES/XRS, SDO/EVE, PROBA2/LYRA), and radio spectra (e-Callisto, STEREO/WAVES). SunPy’s code base is publicly available through github.com and can be contributed to by anyone. In this poster we demonstrate SunPy’s functionality and future goals of the project. We also encourage interested users to become involved in further developing SunPy.

  8. Um fotômetro de fluxo para análises clínicas a base de um diodo emissor de luz bicolor An inexpensive flow photometer for clinical analysis based on a bicolour light emitting diode

    Directory of Open Access Journals (Sweden)

    M. C. U. Araújo

    1997-04-01

    Full Text Available The construction and evaluation of an inexpensive flow photometer for clinical analysis, using a bicolour LED and a phototransistor adapted for tubular flow cell, are described. The instrument presents some new features such as: automatic zero, electronic calibration and peak-hold signal. When compared with a classical photometer, it is simpler and has the advantages of a flow analysis system: lower volumes of reagents and samples, lower levels of contamination, shorter time for analysis and lower analysis costs. The instrument was used in the determination of the constituents in blood samples. The results obtained agree with those obtained by a classical photometer and the precision was better.

  9. The rate of stellar encounters along a migrating orbit of the Sun

    OpenAIRE

    Martínez-Barbosa, C. A.; Jílková, L.; Zwart, S. Portegies; A. G. A. Brown

    2016-01-01

    The frequency of Galactic stellar encounters the Solar system experienced depends on the local density and velocity dispersion along the orbit of the Sun in the Milky Way galaxy. We aim at determining the effect of the radial migration of the solar orbit on the rate of stellar encounters. As a first step we integrate the orbit of the Sun backwards in time in an analytical potential of the Milky Way. We use the present-day phase-space coordinates of the Sun, according to the measured uncertain...

  10. Accuracy assessment of water vapour measurements from in situ and remote sensing techniques during the DEMEVAP 2011 campaign at OHP

    Directory of Open Access Journals (Sweden)

    O. Bock

    2013-10-01

    Full Text Available The Development of Methodologies for Water Vapour Measurement (DEMEVAP project aims at assessing and improving humidity sounding techniques and establishing a reference system based on the combination of Raman lidars, ground-based sensors and GPS. Such a system may be used for climate monitoring, radiosonde bias detection and correction, satellite measurement calibration/validation, and mm-level geodetic positioning with Global Navigation Satellite Systems. A field experiment was conducted in September–October 2011 at Observatoire de Haute-Provence (OHP. Two Raman lidars (IGN mobile lidar and OHP NDACC lidar, a stellar spectrometer (SOPHIE, a differential absorption spectrometer (SAOZ, a sun photometer (AERONET, 5 GPS receivers and 4 types of radiosondes (Vaisala RS92, MODEM M2K2-DC and M10, and Meteolabor Snow White participated in the campaign. A total of 26 balloons with multiple radiosondes were flown during 16 clear nights. This paper presents preliminary findings from the analysis of all these data sets. Several classical Raman lidar calibration methods are evaluated which use either Vaisala RS92 measurements, point capacitive humidity measurements, or GPS integrated water vapour (IWV measurements. A novel method proposed by Bosser et al. (2010 is also tested. It consists in calibrating the lidar measurements during the GPS data processing. The methods achieve a repeatability of 4–5%. Changes in the calibration factor of IGN Raman lidar are evidenced which are attributed to frequent optical re-alignments. When modelling and correcting the changes as a linear function of time, the precision of the calibration factors improves to 2–3%. However, the variations in the calibration factor, and hence the absolute accuracy, between methods and types of reference data remain at the level of 7%. The intercomparison of radiosonde measurements shows good agreement between RS92 and Snow White measurements up to 12 km. An overall dry bias is found

  11. Quest for finding the lost siblings of the Sun

    CERN Document Server

    Liu, C; Feltzing, S; Martínez-Barbosa, C A; Bensby, T; Brown, A G A; Zwart, S F Portegies

    2014-01-01

    The aim of this paper is to find lost siblings of the Sun by analyzing high resolution spectra. Finding solar siblings will enable us to constrain the parameters of the parental cluster and the birth place of the Sun in the Galaxy. The solar siblings can be identified by accurate measurements of metallicity, stellar age and elemental abundances for solar neighbourhood stars. The solar siblings candidates were kinematically selected based on their proper motions, parallaxes and colours. Stellar parameters were determined through a purely spectroscopic approach and partly physical method, respectively. Comparing synthetic with observed spectra, elemental abundances were computed based on the stellar parameters obtained using a partly physical method. A chemical tagging technique was used to identify the solar siblings. We present stellar parameters, stellar ages, and detailed elemental abundances for Na, Mg, Al, Si, Ca, Ti, Cr, Fe, and Ni for 32 solar sibling candidates. Our abundances analysis shows that four ...

  12. Analysis of the application of the optical method to the measurements of the water vapor content in the atmosphere – Part 1: Basic concepts of the measurement technique

    Directory of Open Access Journals (Sweden)

    V. D. Galkin

    2011-05-01

    Full Text Available We retrieved the total content of the atmospheric water vapor (or Integrated Water Vapor, IWV from extensive sets of photometric data obtained since 1995 at Lindenberg Meteorological Observatory with star and sun photometers. Different methods of determination of the empirical parameters that are necessary for the retrieval are discussed. The instruments were independently calibrated using laboratory measurements made at Pulkovo Observatory with the VKM-100 multi-pass vacuum cell. The empirical parameters were also calculated by the simulation of the atmospheric absorption by water vapor, using the MODRAN-4 program package for different model atmospheres. The results are compared to those presented in the literature, obtained with different instruments and methods of the retrieval. The reliability of the empirical parameters, used for the power approximation that links the water vapor content with the observed absorption, is analyzed. Currently, the total (from measurements, calibration, and calculations errors yield the standard uncertainty of about 10 % in the total column water vapor. We discuss the possibilities for improving the accuracy of calibration to ~1 % as indispensable condition in order to make it possible to use data obtained by optical photometry as an independent reference for other methods (GPS, MW-radiometers, lidar, etc.

  13. Imaging Grating SpectroPhotometer (I-GRASP) for Solar Soft X-Ray Spectra and Images from a Cube Sat Mission

    Science.gov (United States)

    Didkovsky, Leonid V.; Wieman, Seth; Woods, Thomas N.; Jones, Andrew; Chao, Weilun

    2016-05-01

    We describe the Soft X-ray Imaging Grating SpectroPhotometer (I-GRASP), a novel spectrophotometer with four times narrower transmission grating period (about 50 nm) compared to the MIT-designed 200 nm gratings successfully used for the SOHO/SEM, the SDO/EVE/ESP, and the Solar Aspect Monitor (SAM) onboard the EVE sounding rocket suite of instruments. The new grating is based on technology developed at the Lawrence Berkeley National Laboratory (LBNL) and provides four to five time greater diffraction dispersion than the 200 nm period gratings. Such new technology will provide detection of both 0.1 nm - resolved solar spectra in about 1.0 to 7.0 nm spectral range and a soft X-ray pin-hole solar image from the I-GRASP instrument that is appropriately sized for a CubeSat platform. The solar observations of this soft X-ray range do not currently have spectral resolution, so I-GRASP concurrent spectral and imaging X-ray observations will be important for:Improvements in modeling of coronal dynamics and heating by comparing measured and modeled spectra through identifying changes in abundances from different active regions- Resolving some differences in certain iron spectral line intensity ratios observed with SAM, identifying key emission lines, and comparing to those modeled with the CHIANTI atomic database- Studying SXR spectral variability for different solar activity periods including solar flares and the 27-day solar rotation- Studying of the Earth’s ionosphere, thermosphere and mesosphere responses using as input the detailed soft X-ray spectra from I-GRASP- Improving solar soft X-ray reference spectra for accurate calculations of absolute solar irradiance from the SDO/EVE/ESP, SDO/EVE/SAM, TIMED/SEE/XPS, and SORCE/XPS channels that have broadband measurements of the 1-7 nm band- Providing validation for the soft X-Ray observations from the MinXSS CubeSat X123 spectrometer (0.04 to 2.5 nm) with the I-GRASP spectral observations from 1.0 to 7.0 nm- Comparing I

  14. CUNY Sun-Earth Research, Space Climate

    Science.gov (United States)

    Cotten, D. E.; Cheung, T. D.; Marchese, P. J.; Johnson, L. P.; Austin, S.; Tremberger, G.

    2007-05-01

    Faculty and students at Queensborough Community College and Medgar Evers College of the City University of New York (CUNY) have, over several years now, employed simple software familiar to most undergraduate students to perform useful calculations, including statistical analyses, regarding various geophysical phenomena. Topics have included Space Weather, Interplanetary Magnetic Field (IMF) direction and strength fluctuations, geomagnetic and ionospheric responses to solar flares, and Coronal Mass Ejection (CME) events. Our statistical analyses have utilized second-order measures of fluctuation of the IMF strength, especially what we now call the Cheung number: the number of times that the value of Sigma-B, as provided by the ACE (Advanced Composition Explorer) data, has exceeded 0.5nT during a 6 hour interval. We have also utilized the Higuchi fractal dimension of various somewhat random fluctuations, including Sigma-B and the brightness or strength of adjacent pixels or data points in somewhat random data sequences in time or spatial dimension, including IMF fluctuations and SOHO (Solar Heliographic Observer) images of the Sun. These we have correlated with each other and with such variables as SEP (Solar Energetic Particle) peak flux, TEC (Total Electron Content) of the ionosphere, and Dst (Disturbance storm-time) in the geomagnetic field. Recent results indicate that the IMF fluctuation measures are well correlated with the SEP peak flux, the Dst, and TEC. Higuchi fractal analysis of SOHO photospheric ultraviolet brightness indicates, consistent with concomitant increased chaos or randomness of photospheric brightness, an increased likelihood of solar flare events or CME affecting interplanetary space and the earth's magnetosphere/ionosphere/atmosphere.

  15. Implications of advanced warning messages on eliminating sun glare disturbances at signalized intersections

    Directory of Open Access Journals (Sweden)

    Qing Li

    2016-08-01

    Full Text Available Due to sun glare disturbances, drivers encounter fatal threats on roadways, particularly at signalized intersections. Many studies have attempted to develop applicable solutions, such as avoiding sun positions, applying road geometric re-directions, and wearing anti-glare glasses. None of these strategies have fully solved the problem. As one of the “Connected Vehicle” practices proposed by the U.S. Department of Transportation, advanced warning messages (AWMs are capable of providing wireless information about traffic controls. AWM acts as a supplement to conventional signs and signals, which can be blocked by obstacles or natural disturbances, such as sun glare. The drivers' smart advisory system (DSAS can provide drivers with AWM. Using a driving simulator this research explores the effects of DSAS messages on driving behaviors under sun glare disturbance. Statistical analyses were applied to assess (1 the negative impacts of sun glare, (2 the compensation of the DSAS AWM to sun glare effects, and (3 the improvement in driving performance due to DSAS AWM. Four performance indexes were measured, including (1 half kinetic energy speed, (2 mean approach speed, (3 brake response time, and (4 braking distance. The effects of the socio-demographic factors, such as gender, age, educational background, and driving experience were also studied. The analytical results illustrate that the DSAS can compensate for reduced visibility due to sun glare and improve driving performance to a normal visual situation, particularly for left turn and through movement.

  16. The sun and space weather Second Edition

    CERN Document Server

    Hanslmeier, Arnold

    2007-01-01

    This second edition is a great enhancement of literature which will help the reader get deeper into the specific topics. There are new sections included such as space weather data sources and examples, new satellite missions, and the latest results. At the end a comprehensive index is given which will allow the reader to quickly find his topics of interest. The Sun and Space weather are two rapidly evolving topics. The importance of the Sun for the Earth, life on Earth, climate and weather processes was recognized long ago by the ancients. Now, for the first time there is a continuous surveillance of solar activity at nearly all wavelengths. These data can be used to improve our understanding of the complex Sun-Earth interaction. The first chapters of the book deal with the Sun as a star and its activity phenomena as well as its activity cycle in order to understand the complex physics of the Sun-Earth system. The reader will see that there are many phenomena but still no definite explanations and models exis...

  17. Long-term analysis of aerosol optical depth over Northeast Asia using a satellite-based measurement: MI Yonsei Aerosol Retrieval Algorithm (YAER)

    Science.gov (United States)

    Kim, Mijin; Kim, Jhoon; Yoon, Jongmin; Chung, Chu-Yong; Chung, Sung-Rae

    2017-04-01

    In 2010, the Korean geostationary earth orbit (GEO) satellite, the Communication, Ocean, and Meteorological Satellite (COMS), was launched including the Meteorological Imager (MI). The MI measures atmospheric condition over Northeast Asia (NEA) using a single visible channel centered at 0.675 μm and four IR channels at 3.75, 6.75, 10.8, 12.0 μm. The visible measurement can also be utilized for the retrieval of aerosol optical properties (AOPs). Since the GEO satellite measurement has an advantage for continuous monitoring of AOPs, we can analyze the spatiotemporal variation of the aerosol using the MI observations over NEA. Therefore, we developed an algorithm to retrieve aerosol optical depth (AOD) using the visible observation of MI, and named as MI Yonsei Aerosol Retrieval Algorithm (YAER). In this study, we investigated the accuracy of MI YAER AOD by comparing the values with the long-term products of AERONET sun-photometer. The result showed that the MI AODs were significantly overestimated than the AERONET values over bright surface in low AOD case. Because the MI visible channel centered at red color range, contribution of aerosol signal to the measured reflectance is relatively lower than the surface contribution. Therefore, the AOD error in low AOD case over bright surface can be a fundamental limitation of the algorithm. Meanwhile, an assumption of background aerosol optical depth (BAOD) could result in the retrieval uncertainty, also. To estimate the surface reflectance by considering polluted air condition over the NEA, we estimated the BAOD from the MODIS dark target (DT) aerosol products by pixel. The satellite-based AOD retrieval, however, largely depends on the accuracy of the surface reflectance estimation especially in low AOD case, and thus, the BAOD could include the uncertainty in surface reflectance estimation of the satellite-based retrieval. Therefore, we re-estimated the BAOD using the ground-based sun-photometer measurement, and

  18. The Sun Sense Study: An Intervention to Improve Sun Protection in Children

    Science.gov (United States)

    Glasser, Alice; Shaheen, Magda; Glenn, Beth A.; Bastani, Roshan

    2010-01-01

    Objectives: To assess the effect of a multicomponent intervention on parental knowledge, sun avoidance behaviors, and sun protection practices in children 3-10 years. Methods: A randomized trial at a pediatric clinic recruited 197 caregiver-child pairs (90% parents). Intervention included a brief presentation and brochure for the parent and…

  19. After the Bell: Developing Sun Sense--Learning about Protection from the Sun's Rays

    Science.gov (United States)

    Farenga, Stephen J.; Ness, Daniel

    2008-01-01

    The American Academy of Dermatology (2008) reports that our students will experience 80% of their lifetime exposure to the Sun by the time they are 18. Further, research has demonstrated that continued exposure to the Sun's ultraviolet rays can lead to skin aging, sunburn, immune suppression, ocular melanoma, cataracts, corneal burns, and even…

  20. 77 FR 34122 - Application of Sun Air Express, LLC, d/b/a Sun Air International for Commuter Authority

    Science.gov (United States)

    2012-06-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Office of the Secretary Application of Sun Air Express, LLC, d/b/a Sun Air International for Commuter... to show cause why it should not issue an order finding Sun Air Express, LLC d/b/a Sun...

  1. The Skin Cancer and Sun Knowledge (SCSK) Scale: Validity, Reliability, and Relationship to Sun-Related Behaviors among Young Western Adults

    Science.gov (United States)

    Day, Ashley K.; Wilson, Carlene; Roberts, Rachel M.; Hutchinson, Amanda D.

    2014-01-01

    Increasing public knowledge remains one of the key aims of skin cancer awareness campaigns, yet diagnosis rates continue to rise. It is essential we measure skin cancer knowledge adequately so as to determine the nature of its relationship to sun-related behaviors. This study investigated the psychometric properties of a new measure of skin cancer…

  2. The Skin Cancer and Sun Knowledge (SCSK) Scale: Validity, Reliability, and Relationship to Sun-Related Behaviors among Young Western Adults

    Science.gov (United States)

    Day, Ashley K.; Wilson, Carlene; Roberts, Rachel M.; Hutchinson, Amanda D.

    2014-01-01

    Increasing public knowledge remains one of the key aims of skin cancer awareness campaigns, yet diagnosis rates continue to rise. It is essential we measure skin cancer knowledge adequately so as to determine the nature of its relationship to sun-related behaviors. This study investigated the psychometric properties of a new measure of skin cancer…

  3. Poynting-Robertson-like Drag at the Sun's Surface

    Science.gov (United States)

    Cunnyngham, Ian; Emilio, Marcelo; Kuhn, Jeff; Scholl, Isabelle; Bush, Rock

    2017-02-01

    The Sun's internal rotation Ω (r ,Θ ) has previously been measured using helioseismology techniques and found to be a complex function of colatitude θ and radius r . From helioseismology and observations of apparently "rooted" solar magnetic tracers, we know that the surface rotates more slowly than much of the interior. The cause of this slow-down is not understood, but it is important for understanding stellar rotation generally and any plausible theory of the solar interior. A new analysis using 5-min solar p -mode limb oscillations as a rotation "tracer" finds an even larger velocity gradient in a thin region at the top of the photosphere. This shear occurs where the solar atmosphere radiates energy and angular momentum. We suggest that the net effect of the photospheric angular momentum loss is similar to Poynting-Robertson "photon braking" on, for example, Sun-orbiting dust. The resultant photospheric torque is readily computed and, over the Sun's lifetime, is found to be comparable to the apparent angular momentum deficit in the near-surface shear layer.

  4. Dynamics of the global Sun from interior to outer atmosphere

    Science.gov (United States)

    Schrijver, Carolus

    2012-07-01

    The Sun is the only star whose magnetic activity can be resolved in stunning detail. Current observational capabilities range from full-sphere coverage to measurements of details more than 10,000 times smaller than that. Acoustic waves enable us to probe the dynamics of the deep interior, while heliospheric imagers reveal the evolution of coronal mass ejections to beyond the orbit of the Earth. This comprehensive view of a magnetically active star, complemented by rapid advances in numerical capabilities, are revealing how the coupled system of interior, atmosphere, and heliosphere evolves dynamically through the sunspot cycle, punctuated by flux emergence, field eruptions, and irradiance variations. The Sun is not only a touchstone for the interpretation of many astrophysical observations, but its variability affects our society in more ways than we routinely appreciate; this drives a need to understand it well enough that forecasts of its electromagnetic weather can be made. This lecture, starting from the very different perspectives of astrophysical curiosity and societal need, focuses on trends near the frontier of our knowledge about the Sun's functioning as a global system.

  5. Energy Input Flux in the Global Quiet-Sun Corona

    Science.gov (United States)

    Mac Cormack, Cecilia; Vásquez, Alberto M.; López Fuentes, Marcelo; Nuevo, Federico A.; Landi, Enrico; Frazin, Richard A.

    2017-07-01

    We present first results of a novel technique that provides, for the first time, constraints on the energy input flux at the coronal base (r ˜ 1.025 R ⊙) of the quiet Sun at a global scale. By combining differential emission measure tomography of EUV images, with global models of the coronal magnetic field, we estimate the energy input flux at the coronal base that is required to maintain thermodynamically stable structures. The technique is described in detail and first applied to data provided by the Extreme Ultraviolet Imager instrument, on board the Solar TErrestrial RElations Observatory mission, and the Atmospheric Imaging Assembly instrument, on board the Solar Dynamics Observatory mission, for two solar rotations with different levels of activity. Our analysis indicates that the typical energy input flux at the coronal base of magnetic loops in the quiet Sun is in the range ˜0.5-2.0 × 105 (erg s-1 cm-2), depending on the structure size and level of activity. A large fraction of this energy input, or even its totality, could be accounted for by Alfvén waves, as shown by recent independent observational estimates derived from determinations of the non-thermal broadening of spectral lines in the coronal base of quiet-Sun regions. This new tomography product will be useful for the validation of coronal heating models in magnetohydrodinamic simulations of the global corona.

  6. A sun holiday is a sunburn holiday

    DEFF Research Database (Denmark)

    Petersen, Bibi; Thieden, Elisabeth; Philipsen, Peter Alshede

    2013-01-01

    Many people take holidays in sunny locations with the express aim of sunbathing. This may result in sunburn, which is a risk factor for skin cancer. We investigated 25 Danish sun seekers during a week's holiday in the Canary Islands. The percentage of body surface area with sunburn was determined......-specific UVR doses after adjustment for sun protection factor. Remarkably, we found that all volunteers sunburned at some point. The risk of sunburn correlated significantly with the adjusted body site-specific UVR dose. Furthermore, there was also a significant relationship between the daily UVR dose...... and percentage of body surface area with sunburn. Our study shows that holiday UVR exposure results in a high risk of sunburn, which potentially increases the risk of skin cancer. Possible protection by melanogenesis is insufficient to protect against sunburn during a 1-week sun holiday. Finally, our data...

  7. Precise nuclear physics for the sun

    Energy Technology Data Exchange (ETDEWEB)

    Bemmerer, Daniel

    2012-07-01

    For many centuries, the study of the Sun has been an important testbed for understanding stars that are further away. One of the first astronomical observations Galileo Galilei made in 1612 with the newly invented telescope concerned the sunspots, and in 1814, Joseph von Fraunhofer employed his new spectroscope to discover the absorption lines in the solar spectrum that are now named after him. Even though more refined and new modes of observation are now available than in the days of Galileo and Fraunhofer, the study of the Sun is still high on the agenda of contemporary science, due to three guiding interests. The first is connected to the ages-old human striving to understand the structure of the larger world surrounding us. Modern telescopes, some of them even based outside the Earth's atmosphere in space, have succeeded in observing astronomical objects that are billions of light-years away. However, for practical reasons precision data that are important for understanding stars can still only be gained from the Sun. In a sense, the observations of far-away astronomical objects thus call for a more precise study of the closeby, of the Sun, for their interpretation. The second interest stems from the human desire to understand the essence of the world, in particular the elementary particles of which it consists. Large accelerators have been constructed to produce and collide these particles. However, man-made machines can never be as luminous as the Sun when it comes to producing particles. Solar neutrinos have thus served not only as an astronomical tool to understand the Sun's inner workings, but their behavior on the way from the Sun to the Earth is also being studied with the aim to understand their nature and interactions. The third interest is strictly connected to life on Earth. A multitude of research has shown that even relatively slight changes in the Earth's climate may strongly affect the living conditions in a number of densely

  8. The Spectrum of Darkonium in the Sun

    CERN Document Server

    Kouvaris, Chris; Nielsen, Niklas Grønlund

    2016-01-01

    Dark matter that gets captured in the Sun may form positronium-like bound states if it self-interacts via light dark photons. In this case, dark matter can either annihilate to dark photons or recombine in bound states which subsequently also decay to dark photons. The fraction of the dark photons that leave the Sun without decaying to Standard Model particles have a characteristic energy spectrum which is a mixture of the direct annihilation process, the decays of ortho- and para- bound states and the recombination process. The ultimate decay of these dark photons to positron-electron pairs (via kinetic mixing) outside the Sun creates a distinct signal that can either identify or set strict constraints on dark photon models.

  9. The spectrum of darkonium in the Sun

    Science.gov (United States)

    Kouvaris, Chris; Langæble, Kasper; Grønlund Nielsen, Niklas

    2016-10-01

    Dark matter that gets captured in the Sun may form positronium-like bound states if it self-interacts via light dark photons. In this case, dark matter can either annihilate to dark photons or recombine in bound states which subsequently also decay to dark photons. The fraction of the dark photons that leave the Sun without decaying to Standard Model particles have a characteristic energy spectrum which is a mixture of the direct annihilation process, the decays of ortho- and para- bound states and the recombination process. The ultimate decay of these dark photons to positron-electron pairs (via kinetic mixing) outside the Sun creates a distinct signal that can either identify or set strict constraints on dark photon models.

  10. The sun since the Bronze Age

    Science.gov (United States)

    Eddy, J. A.

    1976-01-01

    An investigation is conducted concerning the behavior of the sun during the last 7000 years. The C-14 content in carbonaceous fossil material can be used as an indicator regarding the level of solar activity at the time when the carbon was assimilated in the process of photosynthesis. Living trees, such as the bristlecone pine, provide a solar activity record to about 3000 B.C. The record can be extended with the aid of well-preserved dead wood to beyond 5000 B.C. The results of an analysis of solar activity levels as a function of time on the basis of C-14 contents are presented in a graph. Attention is given to the Maunder Minimum, a history of the sun in the last 5000 years, an interpretation of the major C-14 excursions, and the sun and climate history.

  11. 'My Sun' and 'Guided by the Moon'

    Directory of Open Access Journals (Sweden)

    Rebecca Baillie

    2013-07-01

    Full Text Available My Sun and Guided by the Moon (2012 show the heavily pregnant artist with her swollen belly covered in gold and silver leaf. The work is suggestive that the connectivity experienced by an expectant mother, extends outwards, even as far as her relationship with the cosmos. The 'sun' portrait was taken on a bright September morning, and its partner image, the following October, on the night of a full moon. Female cycles and the importance of time passing during a pregnancy are referenced. Interestingly, bearing in mind that the artist gave birth to a son in November, creating the 'moon' portrait felt like a familiar, empowering and yet isolated expression of selfhood, whilst the 'sun/son' version exuded the energy of a collaboration, and stimulated feelings of joy, liberation and potentiality. By seeming contradiction, the boy was born on a full moon, exactly a month to the day that Guided by the Moon was taken.

  12. Semiautomatic sun shots with the WIDIF DIflux

    Directory of Open Access Journals (Sweden)

    J. L. Rasson

    2017-07-01

    Full Text Available The determination of magnetic declination angle entails finding two directions: geographic north and magnetic north. This paper deals with the former. The known way to do it by using the sun's calculable orientation in the sky is improved by using a device based on a WIDIF DIflux theodolite and split photocells positioned on its telescope ocular. Given the WIDIF accurate timing and location provided by the onboard GPS receiver, an astronomical computation can be effected to accurately and quickly determine the sun's azimuth and an auxiliary mark's azimuth. The precise sun's crossing of the split photocell, amplified by the telescope's magnification, allows azimuth accuracies of a few seconds of arc.

  13. What Is the Source of Quiet Sun Transition Region Emission?

    Science.gov (United States)

    Schmit, D. J.; De Pontieu, Bart

    2016-11-01

    Dating back to the first observations of the on-disk corona, there has been a qualitative link between the photosphere’s magnetic network and enhanced transition-temperature plasma emission. These observations led to the development of a general model that describes emission structures through the partitioning of the atmospheric volume with different magnetic loop geometries that exhibit different energetic equilibria. Does the internetwork produce transition-temperature emission? What fraction of network flux connects to the corona? How does quiet Sun emission compare with low-activity Sun-like stars? In this work, we revisit the canonical model of the quiet Sun, with high-resolution observations from the Interface Region Imaging Spectrograph (IRIS) and HMI in hand, to address those questions. We use over 900 deep exposures of Si iv 1393 Å from IRIS along with nearly simultaneous HMI magnetograms to quantify the correlation between transition-temperature emission structures and magnetic field concentrations through a number of novel statistics. Our observational results are coupled with analysis of the Bifrost MHD model and a large-scale potential field model. Our results paint a complex portrait of the quiet Sun. We measure an emission signature in the distant internetwork that cannot be attributed to network contribution. We find that the dimmest regions of emission are not linked to the local vertical magnetic field. Using the MHD simulation, we categorize the emission contribution from cool mid-altitude loops and high-altitude coronal loops and discuss the potential emission contribution of spicules. Our results provide new constraints on the coupled solar atmosphere so that we can build on our understanding of how dynamic thermal and magnetic structures generate the observed phenomena in the transition region.

  14. The aerosol optical properties measurement by ground remote sensing in Zhejiang, China

    Science.gov (United States)

    Wang, Bin; Jiang, Hong; Chen, Jian; Jiang, Zishan; Yu, Shuquan; Ma, Yuandan

    2009-10-01

    The aerosol optical depth was affected by the chemical composition, the particle size and the shape of aerosol as well as the water vapor in the atmosphere; it is an important indicator for air pollution. The special and temporal characteristics of aerosol optical depth (AOD) was measured by CE318 sun-photometer, Angstrom wavelength exponent (Alpha) and the aerosol turbidity coefficient (β) were calculated in Ningbo, Lin'an and Qiandaohu of Zhejiang province from 2007 to 2008. We also analyzed the relationship between AOD and Angstrom wavelength exponent (Alpha) in these stations. The results show that there are different pattern of AOD in this gradient of urban and suburban region. Lin'an station had two peaks of AOD, but Ningbo and Qiandaohu stations had single peak of AOD in measurement year. The difference of AOD seasonal pattern exists in three sites. The Angstrom wavelength exponent (Alpha) analysis suggests that the aerosol sizes in three stations various from fine particle in autumn to coarse particle in spring. The seasonal patterns show that spring air pollution is serious, summer is relatively clean, and autumn and winter are relative serious in three stations.

  15. Screening of fluoroquinolone residues in caprine milk using a 5-kg luminescence photometer

    Science.gov (United States)

    A terbium-sensitized luminescence (TSL) method was developed to screen presence of residues of four fluoroquinolones (FQ) registered in caprine milk in the European Union: enrofloxacin, ciprofloxacin, flumequine, and danofloxacin. After extraction in McIlvaine buffer and SPE cleanup, TSL was measure...

  16. The Sun in Time: Activity and Environment

    Directory of Open Access Journals (Sweden)

    Güdel Manuel

    2007-12-01

    Full Text Available The Sun's magnetic activity has steadily declined during its main-sequence life. While the solar photospheric luminosity was about 30% lower 4.6 Gyr ago when the Sun arrived on the main sequence compared to present-day levels, its faster rotation generated enhanced magnetic activity; magnetic heating processes in the chromosphere, the transition region, and the corona induced ultraviolet, extreme-ultraviolet, and X-ray emission about 10, 100, and 1000 times, respectively, the present-day levels, as inferred from young solar-analog stars. Also, the production rate of accelerated, high-energy particles was orders of magnitude higher than in present-day solar flares, and a much stronger wind escaped from the Sun, permeating the entire solar system. The consequences of the enhanced radiation and particle fluxes from the young Sun were potentially severe for the evolution of solar-system planets and moons. Interactions of high-energy radiation and the solar wind with upper planetary atmospheres may have led to the escape of important amounts of atmospheric constituents. The present dry atmosphere of Venus and the thin atmosphere of Mars may be a product of early irradiation and heating by solar high-energy radiation. High levels of magnetic activity are also inferred for the pre-main sequence Sun. At those stages, interactions of high-energy radiation and particles with the circumsolar disk in which planets eventually formed were important. Traces left in meteorites by energetic particles and anomalous isotopic abundance ratios in meteoritic inclusions may provide evidence for a highly active pre-main sequence Sun. The present article reviews these various issues related to the magnetic activity of the young Sun and the consequent interactions with its environment. The emphasis is on the phenomenology related to the production of high-energy photons and particles. Apart from the activity on the young Sun, systematic trends applicable to the entire

  17. The sun and heliosphere at solar maximum.

    Science.gov (United States)

    Smith, E J; Marsden, R G; Balogh, A; Gloeckler, G; Geiss, J; McComas, D J; McKibben, R B; MacDowall, R J; Lanzerotti, L J; Krupp, N; Krueger, H; Landgraf, M

    2003-11-14

    Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun's rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.

  18. Haloes around the Moon and the Sun

    Science.gov (United States)

    Gaina, Alex; Gaina, Danielle A.

    2008-10-01

    The authors observations of the Haloes around the Moon and the Sun during few last years are reported. A Historical review of the phenomenon is given since the observations by Benvenuto Cellini and Gaston Tissandier is given. A photograph (from eight available) of the Halo around the Sun observed in Chisinau on 21 May 2007 is included. The Halo from 21 May 2007 occured after a very fast increasing of the air temperature during one day by more than 15 Deg. The authors consider, that the phenomenon is due to scattering of light on Cirri clouds(7 km altitude), present on the sky during that day. They formed due to very fast heating.

  19. SunShot Initiative Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    DOE Solar Energy Technologies Office

    2015-04-01

    The U.S. Department of Energy (DOE) SunShot Initiative is a collaborative national effort launched in 2011 that aggressively drives innovation to make solar energy fully cost competitive with traditional energy sources before the end of the decade. The SunShot fact sheet outlines goals and successes of the program as it works with private companies, universities, non-profit organizations, state and local governments, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour, without incentives, by the year 2020.

  20. The shrinking Sun: a systematic error in local correlation tracking of solar granulation

    CERN Document Server

    Löptien, B; Duvall, T L; Gizon, L; Schou, J

    2016-01-01

    Context. Local correlation tracking of granulation (LCT) is an important method for measuring horizontal flows in the photosphere. This method exhibits a systematic error that looks like a flow converging towards disk center, also known as the shrinking-Sun effect. Aims. We aim at studying the nature of the shrinking-Sun effect for continuum intensity data and at deriving a simple model that can explain its origin. Methods. We derived LCT flow maps by running the local correlation tracking code FLCT on tracked and remapped continuum intensity maps provided by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory. We also computed flow maps from synthetic continuum images generated from STAGGER code simulations of solar surface convection. We investigated the origin of the shrinking-Sun effect by generating an average granule from synthetic data from the simulations. Results. The LCT flow maps derived from HMI and from the simulations exhibit a shrinking-Sun effect of comparable mag...

  1. High temporal resolution estimates of columnar aerosol microphysical parameters from spectrum of aerosol optical depth by linear estimation: application to long-term AERONET and star-photometry measurements

    Science.gov (United States)

    Perez-Ramirez, D.; Veselovskii, I.; Whiteman, D. N.; Suvorina, A.; Korenskiy, M.; Kolgotin, A.; Holben, B.; Dubovik, O.; Siniuk, A.; Alados-Arboledas, L.

    2015-08-01

    This work deals with the applicability of the linear estimation technique (LE) to invert spectral measurements of aerosol optical depth (AOD) provided by AERONET CIMEL sun photometers. The inversion of particle properties using only direct-sun AODs allows the evaluation of parameters such as effective radius (reff) and columnar volume aerosol content (V) with significantly better temporal resolution than the operational AERONET algorithm which requires both direct sun and sky radiance measurements. Sensitivity studies performed demonstrate that the constraints on the range of the inversion are very important to minimize the uncertainties, and therefore estimates of reff can be obtained with uncertainties less than 30 % and of V with uncertainties below 40 %. The LE technique is applied to data acquired at five AERONET sites influenced by different aerosol types and the retrievals are compared with the results of the operational AERONET code. Good agreement between the two techniques is obtained when the fine mode predominates, while for coarse mode cases the LE results systematically underestimate both reff and V. The highest differences are found for cases where no mode predominates. To minimize these biases, correction functions are developed using the multi-year database of observations at selected sites, where the AERONET retrieval is used as the reference. The derived corrections are tested using data from 18 other AERONET stations offering a range of aerosol types. After correction, the LE retrievals provide better agreement with AERONET for all the sites considered. Finally, the LE approach developed here is applied to AERONET and star-photometry measurements in the city of Granada (Spain) to obtain day-to-night time evolution of columnar aerosol microphysical properties.

  2. BcSUN1, a B. cinerea SUN-Family Protein, Is Involved in Virulence

    Science.gov (United States)

    Pérez-Hernández, Alicia; González, Mario; González, Celedonio; van Kan, Jan A. L.; Brito, Nélida

    2017-01-01

    BcSUN1 is a glycoprotein secreted by Botrytis cinerea, an important plant pathogen that causes severe losses in agriculture worldwide. In this work, the role of BcSUN1 in different aspects of the B. cinerea biology was studied by phenotypic analysis of Bcsun1 knockout strains. We identified BcSUN1 as the only member of the Group-I SUN family of proteins encoded in the B. cinerea genome, which is expressed both in axenic culture and during infection. BcSUN1 is also weakly attached to the cellular surface and is involved in maintaining the structure of the cell wall and/or the extracellular matrix. Disruption of the Bcsun1 gene produces different cell surface alterations affecting the production of reproductive structures and adhesion to plant surface, therefore reducing B. cinerea virulence. BcSUN1 is the first member of the SUN family reported to be involved in the pathogenesis of a filamentous fungus. PMID:28163701

  3. Assessment of the sensitivity of core/shell parameters derived using the single-particle soot photometer to density and refractive index

    Directory of Open Access Journals (Sweden)

    J. W. Taylor

    2014-06-01

    Full Text Available Black carbon (BC is the dominant absorbing aerosol in the atmosphere, and plays an important role in climate and human health. The optical properties and cloud condensation nuclei (CCN activity of soot depend on the amounts (both relative and absolute of BC and nonrefractory material in the particles. Mixing between these two components is often considered using a core/shell coated sphere morphology. The Single Particle Soot Photometer (SP2 is the premier instrument for reporting distributions of both core size and coating thickness. Most studies combine the SP2's incandescence and scattering data to report coating properties, but there is variation in the assumed density and refractive index of the core that are used in these calculations. In this study we explore the sensitivity of the reported coatings to these parameters. An assessment of the coating properties of freshly-emitted, thermodenuded ambient particles demonstrated that a core density of 1.8 g cm−3 and refractive index n = (2.26-1.26i were the most appropriate to use with ambient soot in the Los Angeles area. Using these parameters generated a distribution of shell/core ratio of 1.04 ± 0.21, corresponding to an absolute coating thickness distribution of 1.7 ± 17.5 nm. This demonstrates that using this technique the SP2 can accurately determine the mixing state (externally or internally mixed of ambient soot, but with limited precision. Using other core parameters resulted in an offset in the coating distribution, but similar precision. For comparison, using the core parameters that resulted in the thickest coatings (on the same particles as before generated a distribution of shell/core ratio of 1.40 ± 0.19, corresponding to an absolute coating thickness distribution of 30.3 ± 14.9 nm. Relative changes in coatings associated with secondary aerosol condensation were captured regardless of the assumed core parameters. These results must be taken into account when comparing BC

  4. Autonomous Field Measurements of CO2 in the Atmospheric Column with the Miniaturized Laser Heterodyne Radiometer (Mini-LHR)

    Science.gov (United States)

    Melroy, H. R.; Wilson, E. L.; Clarke, G. B.; Ott, L. E.; Mao, J.; Ramanathan, A. K.; McLinden, M. L.

    2015-01-01

    We present column CO2 measurements taken by the passive Miniaturized Laser Heterodyne Radiometer (Mini-LHR) at 1611.51 nm at the Mauna Loa Observatory (MLO) in Hawaii. The Mini-LHR was operated autonomously, during the month of May 2013 at this site, working in tandem with an AERONET sun photometer that measures aerosol optical depth at 15 minute intervals during daylight hours. Laser Heterodyne Radiometry has been used since the 1970s to measure atmospheric gases such as ozone, water vapor, methane, ammonia, chlorine monoxide, and nitrous oxide. This iteration of the technology utilizes distributed feedback lasers to produce a low-cost, small, portable sensor that has potential for global deployment. Applications of this instrument include supplementation of existing monitoring networks to provide denser global coverage, providing validation for larger satellite missions, and targeting regions of carbon flux uncertainty. Also presented here is a preliminary retrieval analysis and the performance analysis that demonstrates that the Mini-LHR responds extremely well to changes in the atmospheric absorption.

  5. JPSS-1 VIIRS solar diffuser stability monitor response versus sun angle of incidence

    Science.gov (United States)

    Murgai, Vijay; Yu, Kristie; Nelson, Neil; McCarthy, James

    2015-09-01

    The Visible/Infrared Imaging Radiometer Suite (VIIRS) is a key sensor on the Suomi National Polar-orbiting Partnership (NPP) satellite in orbit as well as for the upcoming Joint Polar Satellite System (JPSS). VIIRS collects Earth radiometry and imagery in 22 spectral from 0.4 to 12.5 μm. Radiometric calibration of the reflective bands in the 0.4 to 2.5 μm wavelength range is performed by measuring the sunlight reflectance from Solar Diffuser Assembly (diffuser is Spectralon®). Spectralon® is known to solarize due to sun UV exposure at the blue end of the spectrum (~0.4 - 0.6+ μm) as seen by laboratory tests as well as on orbit data from MODIS and NPP. VIIRS uses a Solar Diffuser Stability Monitor (SDSM) to monitor the change in the Solar Diffuser reflectance in the 0.4 - 0.94 μm wavelength range to correct the calibration constants. The SDSM measures the ratio of sun light reflecting from the Solar Diffuser to a direct view of the sun. As the intensity of the light reaching the SDSM in both Solar Diffuser view and sun view is a function of the sun's angle of incidence (AOI), the SDSM response to sun AOI has to be characterized. This paper presents details of the test setup including an extended collimated source simulating the sun across all SDSM bands. The prelaunch characterization results for the JPSS-1 (J1) VIIRS SDSM are presented. Comparison with NPP on orbit yaw maneuver SDSM results shows similar behavior demonstrating that the J1 test successfully characterized the SDSM response to sun AOI.

  6. Measurement of aerosol optical depth and sub-visual cloud detection using the optical depth sensor (ODS

    Directory of Open Access Journals (Sweden)

    D. Toledo

    2015-09-01

    Full Text Available A small and sophisticated optical depth sensor (ODS has been designed to work in the atmosphere of Earth and Mars. The instrument measures alternatively the diffuse radiation from the sky and the attenuated direct radiation from the sun on the surface. The principal goals of ODS are to retrieve the daily mean aerosol optical depth (AOD and to detect very high and optically thin clouds, crucial parameters in understanding the Martian and Earth meteorology and climatology. The detection of clouds is undertaken at twilight, allowing the detection and characterization of clouds with opacities below 0.03 (sub-visual clouds. In addition, ODS is capable to retrieve the aerosol optical depth during night-time from moonlight measurements. In order to study the performance of ODS under Mars-like conditions as well as to evaluate the retrieval algorithms for terrestrial measurements, ODS was deployed in Ouagadougou (Africa between November 2004 and October 2005, a sahelian region characterized by its high dust aerosol load and the frequent occurrence of Saharan dust storms. The daily average AOD values retrieved by ODS were compared with those provided by a CIMEL Sun-photometer of the AERONET (Aerosol Robotic NETwork network localized at the same location. Results represent a good agreement between both ground-based instruments, with a correlation coefficient of 0.79 for the whole data set and 0.96 considering only the cloud-free days. From the whole dataset, a total of 71 sub-visual cirrus (SVC were detected at twilight with opacities as thin as 1.10−3 and with a maximum of occurrence at altitudes between 14 and 20 km. Although further analysis and comparisons are required, results indicate the potential of ODS measurements to detect sub-visual clouds.

  7. Rational SU(N) Gaudin Model

    Institute of Scientific and Technical Information of China (English)

    曹俊鹏; 侯伯宇; 岳瑞宏

    2001-01-01

    We propose the eigenstates and eigenvalues of Hamiltonians of the rational SU(N) Gaudin model based onthe quasi-classical limit of the SU ( N) chain under the periodic boundary condition. Using the quantum inversescattering method, we also obtain the eigenvalues of the generation function of the rational SU ( N) Gaudin model.

  8. Asymmetric dark matter and the Sun

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal; Sarkar, Subir

    2010-01-01

    Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure...

  9. SunPy - Python for Solar Physics

    CERN Document Server

    Community, The SunPy; Christe, Steven; Pérez-Suárez, David; Ireland, Jack; Shih, Albert Y; Inglis, Andrew R; Liedtke, Simon; Hewett, Russell J; Mayer, Florian; Hughitt, Keith; Freij, Nabil; Meszaros, Tomas; Bennett, Samuel M; Malocha, Michael; Evans, John; Agrawal, Ankit; Leonard, Andrew J; Robitaille, Thomas P; Mampaey, Benjamin; Campos-Rozo, Jose Iván; Kirk, Michael S

    2015-01-01

    This paper presents SunPy (version 0.5), a community-developed Python package for solar physics. Python, a free, cross-platform, general-purpose, high-level programming language, has seen widespread adoption among the scientific community, resulting in the availability of a large number of software packages, from numerical computation (NumPy, SciPy) and machine learning (scikit-learn) to visualisation and plotting (matplotlib). SunPy is a data-analysis environment specialising in providing the software necessary to analyse solar and heliospheric data in Python. SunPy is open-source software (BSD licence) and has an open and transparent development workflow that anyone can contribute to. SunPy provides access to solar data through integration with the Virtual Solar Observatory (VSO), the Heliophysics Event Knowledgebase (HEK), and the HELiophysics Integrated Observatory (HELIO) webservices. It currently supports image data from major solar missions (e.g., SDO, SOHO, STEREO, and IRIS), time-series data from mis...

  10. Essential Outdoor Sun Safety Tips for Winter

    Science.gov (United States)

    ... ve Got Skin in the Game Anti-Aging Vitamin D Related: What Is Skin Cancer? | True Stories | Ask the Experts Blog Events ... Weekend Warriors expand/collapse Golf: You've Got Skin in the Game expand/collapse Vitamin D Essential Outdoor Sun Safety Tips for Winter ...

  11. Sino-Sun Architects & Engineers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Sino-Sun is an A-Class state architectural design company organized by a group of experts who have returned to China after studying abroad. In the 10 yearssince its establishment, it has grown into an outstanding andwell-known design team, which has influence in the national archi-tectural design field.

  12. Ulysses Passes South Pole of Sun

    Institute of Scientific and Technical Information of China (English)

    程林

    1995-01-01

    On the 14th of September,1994, the fastest scientific instrument in space passed the south pole of the Sun,a place where no human-made object has been before. A spaceprobe called Ulysses made the polar pass at about midday as it continued to collect data on the solar wind,a stream of high-energy sub-atomic

  13. Sun Baiqiu Fights for the Human Cause

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    SUN Baiqiu liked to read well known literature from all over the world when she was a little girl. She sympathized with the good-hearted characters and hated the greedy and the evil. She imagined that she would become like a fairy godmother, holding a magic wand and helping the poor but kind people in distress. In 1963 she graduated from Haerbin

  14. The Sun in Time: Activity and Environment

    CERN Document Server

    Güdel, M

    2007-01-01

    (abridged) The Sun's magnetic activity has steadily declined during its main-sequence life. While the solar photospheric luminosity was about 30% lower 4.6 Gyr ago when the Sun arrived on the main sequence compared to present-day levels, its faster rotation generated enhanced magnetic activity; magnetic heating processes in the chromosphere, the transition region, and the corona induced ultraviolet, extreme-ultraviolet, and X-ray emission about 10, 100, and 1000 times, respectively, the present-day levels, as inferred from young solar-analog stars. Also, the production rate of accelerated, high-energy particles was orders of magnitude higher than in present-day solar flares, and a much stronger wind escaped from the Sun, permeating the entire solar system. The consequences of the enhanced radiation and particle fluxes from the young Sun were potentially severe for the evolution of solar-system planets and moons. Interactions of high-energy radiation and the solar wind with upper planetary atmospheres may have...

  15. Sunburn related to UV radiation exposure, age, sex, occupation, and sun bed use based on time-stamped personal dosimetry and sun behavior diaries.

    Science.gov (United States)

    Thieden, Elisabeth; Philipsen, Peter A; Sandby-Møller, Jane; Wulf, Hans Christian

    2005-04-01

    To assess when sunburn occurs and who experiences sunburn by personal UV dosimetry and diaries. Open prospective observational study. University hospital. A convenience sample of 340 Danish volunteers: children, adolescents, indoor workers, sun worshippers, golfers, and gardeners (age range, 4-68 years). Subjects recorded sunburn and sun-exposure behavior in diaries and carried personal, electronic, wristwatch UV radiation (UVR) dosimeters that measured time-stamped UVR doses continuously for a median of 119 days covering 346 sun-years (1 sun-year equals 1 subject participating during 1 summer half-year). A typical sunburn day was a day off work (91%; odds ratio, 4.1) with risk behavior (sunbathing/exposing shoulders) (79%; odds ratio, 15.9) in May, June, or July (90%) for 6.4 exposure hours (interquartile range, 5-7.7 hours), of which 2.8 hours fell between noon and 3 pm. Subjects had a median of 1 sunburn per sun-year; adolescents, sun worshippers, and indoor workers had more than children, golfers, and gardeners (Ppersons had more risk-behavior days and lower skin type (Ppersons. The median UVR doses received were significantly higher on sunburn days than on nonsunburn days with risk behavior (P<.01). There was a significant correlation between sunburn size and severity; sunburn and sunscreen use; and sunburn and sun-bed use (P<.01 for all 3 comparisons). Sunburn was highly correlated with risk behavior. Reduction of risk-behavior days and/or exposure hours around noon can reduce sunburn. Sunburn was not found during breaks on normal full-time indoor work or school days.

  16. On-board data processing for the near infrared spectrograph and photometer instrument (NISP) of the EUCLID mission

    Science.gov (United States)

    Bonoli, Carlotta; Balestra, Andrea; Bortoletto, Favio; D'Alessandro, Maurizio; Farinelli, Ruben; Medinaceli, Eduardo; Stephen, John; Borsato, Enrico; Dusini, Stefano; Laudisio, Fulvio; Sirignano, Chiara; Ventura, Sandro; Auricchio, Natalia; Corcione, Leonardo; Franceschi, Enrico; Ligori, Sebastiano; Morgante, Gianluca; Patrizii, Laura; Sirri, Gabriele; Trifoglio, Massimo; Valenziano, Luca

    2016-07-01

    The Near Infrared Spectrograph and Photometer (NISP) is one of the two instruments on board the EUCLID mission now under implementation phase; VIS, the Visible Imager is the second instrument working on the same shared optical beam. The NISP focal plane is based on a detector mosaic deploying 16x, 2048x2048 pixels^2 HAWAII-II HgCdTe detectors, now in advanced delivery phase from Teledyne Imaging Scientific (TIS), and will provide NIR imaging in three bands (Y, J, H) plus slit-less spectroscopy in the range 0.9÷2.0 micron. All the NISP observational modes will be supported by different parametrization of the classic multi-accumulation IR detector readout mode covering the specific needs for spectroscopic, photometric and calibration exposures. Due to the large number of deployed detectors and to the limited satellite telemetry available to ground, a consistent part of the data processing, conventionally performed off-line, will be accomplished on board, in parallel with the flow of data acquisitions. This has led to the development of a specific on-board, HW/SW, data processing pipeline, and to the design of computationally performing control electronics, suited to cope with the time constraints of the NISP acquisition sequences during the sky survey. In this paper we present the architecture of the NISP on-board processing system, directly interfaced to the SIDECAR ASICs system managing the detector focal plane, and the implementation of the on-board pipe-line allowing all the basic operations of input frame averaging, final frame interpolation and data-volume compression before ground down-link.

  17. Quest for the lost siblings of the Sun

    Science.gov (United States)

    Liu, C.; Ruchti, G.; Feltzing, S.; Martínez-Barbosa, C. A.; Bensby, T.; Brown, A. G. A.; Portegies Zwart, S. F.

    2015-03-01

    Aims: The aim of this paper is to find lost siblings of the Sun by analyzing high resolution spectra. Finding solar siblings will enable us to constrain the parameters of the parental cluster and the birth place of the Sun in the Galaxy. Methods: The solar siblings can be identified by accurate measurements of metallicity, stellar age and elemental abundances for solar neighbourhood stars. The solar siblings candidates were kinematically selected based on their proper motions, parallaxes and colours. Stellar parameters were determined through a purely spectroscopic approach and partly physical method, respectively. Comparing synthetic with observed spectra, elemental abundances were computed based on the stellar parameters obtained using a partly physical method. A chemical tagging technique was used to identify the solar siblings. Results: We present stellar parameters, stellar ages, and detailed elemental abundances for Na, Mg, Al, Si, Ca, Ti, Cr, Fe, and Ni for 32 solar sibling candidates. Our abundances analysis shows that four stars are chemically homogenous together with the Sun. Technique of chemical tagging gives us a high probability that they might be from the same open cluster. Only one candidate - HIP 40317 - which has solar metallicity and age could be a solar sibling. We performed simulations of the Sun's birth cluster in analytical Galactic model and found that most of the radial velocities of the solar siblings lie in the range -10 ≤ Vr ≤ 10 km s-1, which is smaller than the radial velocity of HIP 40317 (Vr = 34.2 km s-1), under different Galactic parameters and different initial conditions of the Sun's birth cluster. The sibling status for HIP 40317 is not directly supported by our dynamical analysis. Based on observations made with Nordic Optical Telescope at La Palma under programme 44-014. Based on observations made with ESO VLT Kueyen Telescope at the Paranal observatory under program me ID 085.C-0062(A), 087.D-0010(A), and 088.B-0820(A

  18. Do radioactive half-lives vary with the Earth-to-Sun distance?

    CERN Document Server

    Hardy, J C; Iacob, V E

    2011-01-01

    Recently, Jenkins, Fischbach and collaborators have claimed evidence that radioactive half-lives vary systematically over a +/- 0.1% range as a function of the oscillating distance between the Earth and the Sun, based on multi-year activity measurements. We have avoided the time-dependent instabilities to which such measurements are susceptible by directly measuring the half-life of 198Au (t1/2 = 2.695 d) on seven occasions spread out in time to cover the complete range of Earth-Sun distances. We observe no systematic oscillations in half-life and can set an upper limit on their amplitude of +/- 0.02%.

  19. School Sun-Protection Policies--Does Being SunSmart Make a Difference?

    Science.gov (United States)

    Turner, Denise; Harrison, Simone L.; Buettner, Petra; Nowak, Madeleine

    2014-01-01

    Evaluate the comprehensiveness of primary school sun-protection policies in tropical North Queensland, Australia. Pre-determined criteria were used to assess publicly available sun-protection policies from primary schools in Townsville (latitude 19.3°S; n = 43), Cairns (16.9°S; n = 46) and the Atherton Tablelands (17.3°S; n = 23) during 2009-2012.…

  20. Retrieval of columnar water vapor using multispectral radiometer measurements over northern China

    Science.gov (United States)

    Liu, Chaoshun; Li, Yun; Gao, Wei; Shi, Runhe; Bai, Kaixu

    2011-01-01

    Water vapor is an important component in hydrological processes that basically involve all types of seasons, including dry (e.g., drought) or wet (e.g., hurricane or monsoon). This study retrieved columnar water vapor (CWV) with the 939.3 nm band of a multifilter rotating shadowband radiometer (MFRSR) using the modified Langley technique. Such an investigation was in concert with the use of the atmospheric transmission model MODTRAN for determining the instrument coefficients required for CWV estimation. Results of the retrieval of CWV by MFRSR from September 23, 2004 to June 20, 2005 at the XiangHe site are presented and analyzed in this paper. To improve the credibility, the MFRSR results were compared with those obtained from the AErosol RObotic NETwork CIMEL sun-photometer measurements, co-located at the XiangHe site, and the moderate resolution imaging spectroradiometer (MODIS) near-infrared total precipitable water product (MOD05), respectively. These comparisons show good agreement in terms of correlation coefficients, slopes, and offsets, revealing that the accuracy of CWV estimation using the MFRSR instrument is reliable and suitable for extended studies in northern China.

  1. Raising sun protection and early detection awareness among Florida high schoolers.

    Science.gov (United States)

    Geller, Alan C; Shamban, Jill; O'Riordan, David L; Slygh, Carolyn; Kinney, John P; Rosenberg, Steven

    2005-01-01

    Changing adolescents' sun protection behaviors remains a challenge, and the need for effective interventions targeting this group is a priority, particularly in warmer climates where emphasis on appropriate sun protection remains a year-round concern. However, there has been little prospective research on the effect of school-based sun protection interventions, particularly on adolescents, especially teens aged 15 to 18. High school science students in Palm Beach County, Florida, received a seven-lesson sun protection and early detection curriculum preceded by pretests and followed with post-tests 6 months later. The main outcome measures were student knowledge and sun protection practices, including adherence to sunscreen recommendations. Of 344 students completing the baseline surveys, 184 students completed the postintervention questionnaire. Overall, there were significant improvements from baseline to follow-up for many of the knowledge questions. Greatest change scores were seen in the children's ability to correctly define the five rules of early detection of skin cancer (27-60%, pchallenges and obstacles and thus, further work is needed to better understand what combination of knowledge-based information, activity-based education, school-wide changes, and community efforts, will create a long-term systemic improvement in sun protection habits in children.

  2. Observing the Sun with NuSTAR

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) is a space telescope primarily designed to detect high-energy X-rays from faint, distant astrophysical sources. Recently, however, its occasionally been pointing much closer to home, with the goal of solving a few longstanding mysteries about the Sun.Intensity maps from an observation of a quiet-Sun region near the north solar pole and an active region just below the solar limb. The quiet-Sun data will be searched for small flares that could be heating the solar corona, and the high-altitude emission above the limb may provide clues about particle acceleration. [Adapted from Grefenstette et al. 2016]An Unexpected TargetThough we have a small fleet of space telescopes designed to observe the Sun, theres an important gap: until recently, there was no focusing telescope making solar observations in the hard X-ray band (above ~3 keV). Conveniently, there is a tool capable of doing this: NuSTAR.Though NuSTARs primary mission is to observe faint astrophysical X-ray sources, a team of scientists has recently conducted a series of observations in which NuSTAR was temporarily repurposed and turned to focus on the Sun instead.These observations pose an interesting challenge precisely because of NuSTARs extreme sensitivity: pointing at such a nearby, bright source can quickly swamp the detectors. But though the instrument cant be used to observe the bright flares and outbursts from the Sun, its the perfect tool for examining the parts of the Sun weve been unable to explore in hard X-rays before now such as faint flares, or the quiet, inactive solar surface.In a recently published study led by Brian Grefenstette (California Institute of Technology), the team describes the purpose and initial results of NuSTARs first observations of the Sun.Solar MysteriesWhat is NuSTAR hoping to accomplish with its solar observations? There are two main questions that hard X-ray observations may help to answer.How are particles accelerated in

  3. Analysis of the application of the optical method to the measurements of the water vapor content in the atmosphere – Part 1: Basic concepts – the measurements of the water vapor content in the atmosphere with the optical method

    Directory of Open Access Journals (Sweden)

    V. D. Galkin

    2010-12-01

    Full Text Available We retrieved the total content of the atmospheric water vapor from extensive sets of photometric data obtained since 1995 at Lindenberg Meteorological Observatory with star and sun photometers. Different methods of determination of the empirical parameters that are necessary for the retrieval are discussed. The instruments were independently calibrated using laboratory measurements made at Pulkovo Observatory with the VKM-100 multi-pass vacuum cell. The empirical parameters were also calculated by the simulation of the atmospheric absorption by water vapor, using the MODRAN-4 program package for different model atmospheres. The results are compared to those presented in the literature, obtained with different instruments and methods of the retrieval. The accuracy of the empirical parameters used for the power approximation that links the water vapor content with the observed absorption is analyzed. Currently, the calibration and measurement errors yield the uncertainty of about 10% in the total column water vapor. We discuss the possibilities for improving the accuracy of calibration to ~1%, which will make it possible to use data obtained by optical photometry as an independent reference for other methods (GPS, lidar, etc.

  4. Detection of Planetary Transits Across a Sun-like Star

    CERN Document Server

    Charbonneau, D; Latham, D W; Mayor, M; Charbonneau, David; Brown, Timothy M.; Latham, David W.; Mayor, Michel

    1999-01-01

    We report high precision, high cadence photometric measurements of the star HD 209458, which is known from radial velocity measurements to have a planetary mass companion in a close orbit. We detect two separate transit events at times that are consistent with the radial velocity measurements. In both cases, the detailed shape of the transit curve due to both the limb darkening of the star and the finite size of the planet is clearly evident. Assuming stellar parameters of 1.1 R_Sun and 1.1 M_Sun, we find that the data are best interpreted as a gas giant with a radius of 1.27 +/- 0.02 R_Jup in an orbit with an inclination of 87.1 +/- 0.2 degrees. We present values for the planetary surface gravity, escape velocity, and average density, and discuss the numerous observations that are warranted now that a planet is known to transit the disk of its parent star.

  5. On testing of the photometer-polarimeter UVP layout using a telescope on Earth's surface

    Science.gov (United States)

    Nevodovskyi, P. V.; Vidmachenko, A. P.; Morozhenko, O. V.; Zbrutskyi, O.; Ivakhiv, O. V.

    2016-08-01

    . V. Studies of stratospheric ozone layer from near-earth orbit utilizing ultraviolet polarimeter // Acta Astronautica. 2009, vol. 64, no 1, p. 54-58. 3. Nevodovskij P. V. Kvantakons and optimization of their parameters for astronomical observations Kinematika i Fizika Nebesnykh Tel. 2001, vol. 17, no. 3, p. 279-288. 4. A. P. Vid'machenko, P. V. Nevodovsky. A cooled photomultiplier with an InGaAs photocathode developed for the spectropolarimetry observations // Kinematika i Fizika Nebesnykh Tel. 2000. Suppl. 3, p. 283-285. 5. Morozhenko A. V., Vidmachenko A. P., Nevodovskiy P. V., Kostogryz N. M. On the efficiency of polarization measurements while studying aerosols in the terrestrial atmosphere // Kinematics and Physics of Celestial Bodies. 2014, vol. 30, no. 1, p. 11-21. 6. A.V. Morozhenko, A.P. Vidmachenko, P.V. Nevodovskyi. Aerosol in the upper layer of earth's atmosphere // Kinematics and Physics of Celestial Bodies. 2013, vol. 29, no. 5, p. 243-246. 7. Morozhenko A.V. Polarimetry of twilight sky and stratospheric aerosol // Kinematics and Physics of Celestial Bodies. 2010, vol. 26, no. 1, p. 36-38.

  6. Comparison between calculations of shortwave radiation with different aerosol datasets and measured data at the MSU MO (Russia)

    Science.gov (United States)

    Poliukhov, Aleksei; Chubarova, Natalia; Kinne, Stephan; Rivin, Gdaliy; Shatunova, Marina; Tarasova, Tatiana

    2017-02-01

    The radiation block of the COSMO non-hydrostatic mesoscale model of the atmosphere and soil active layer was tested against a relatively new effective CLIRAD(FC05)-SW radiation model and radiative measurements at the Moscow State University Meteorological Observatory (MSU MO, 55.7N, 37.5E) using different aerosol datasets in cloudless conditions. We used the data of shortwave radiation components from the Kipp&Zonen net radiometer CNR4. The model simulations were performed with the application of various aerosol climatologies including the new MACv2 climatology and the aerosol and water vapor dataset from CIMEL (AERONET) sun photometer measurements. The application of the new MACv2 climatology in the CLIRAD(FC05)-SW radiation model provides the annual average relative error of the total global radiation of -3% varying from 0.5% in May to -7.7% in December. The uncertainty of radiative calculations in the COSMO model according to preliminary estimates changes from 1.4% to 8.4%. against CLIRAD(FC05)-SW radiation model with the same parameters. We showed that in clear sky conditions the sensitivity of air temperature at 2 meters to shortwave net radiation changes is about 0.7-0.9°C per100 W/m2 due to the application of aerosol climatologies over Moscow.

  7. Aerosol optical properties over the Svalbard region of Arctic: ground-based measurements and satellite remote sensing

    Science.gov (United States)

    Gogoi, Mukunda M.; Babu, S. Suresh

    2016-05-01

    In view of the increasing anthropogenic presence and influence of aerosols in the northern polar regions, long-term continuous measurements of aerosol optical parameters have been investigated over the Svalbard region of Norwegian Arctic (Ny-Ålesund, 79°N, 12°E, 8 m ASL). This study has shown a consistent enhancement in the aerosol scattering and absorption coefficients during spring. The relative dominance of absorbing aerosols is more near the surface (lower single scattering albedo), compared to that at the higher altitude. This is indicative of the presence of local anthropogenic activities. In addition, long-range transported biomass burning aerosols (inferred from the spectral variation of absorption coefficient) also contribute significantly to the higher aerosol absorption in the Arctic spring. Aerosol optical depth (AOD) estimates from ground based Microtop sun-photometer measurements reveals that the columnar abundance of aerosols reaches the peak during spring season. Comparison of AODs between ground based and satellite remote sensing indicates that deep blue algorithm of Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals over Arctic snow surfaces overestimate the columnar AOD.

  8. Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR: Instrument Technology

    Directory of Open Access Journals (Sweden)

    Yohei Shinozuka

    2013-08-01

    Full Text Available The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air-pollution/climate. Direct beam hyper-spectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements will tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. Technical challenges include compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage. Test results establishing the performance of the instrument against the full range of operational requirements are presented, along with calibration, engineering flight test, and scientific field campaign data and results.

  9. UV photography, masculinity, and college men's sun protection cognitions.

    Science.gov (United States)

    Walsh, Laura A; Stock, Michelle L

    2012-08-01

    This study examined the impact of an ultraviolet (UV) photography intervention and masculinity on college men's sun protection cognitions, including: perceived vulnerability to skin damage, attitudes toward sun protection, willingness to engage in sun protection behaviors, and intentions to receive a skin cancer exam. After completing a baseline survey, participants (N = 152) viewed a black-and-white photo of their face. Half also viewed a photo showing their UV damage. Participants then completed a second survey assessing sun protection cognitions. Regressions revealed that masculinity predicted lower sun protection cognitions, and men in the UV photograph condition reported higher sun protection cognitions. Masculinity by condition interactions showed that the positive effect of UV photography was stronger among masculine men. Negative associations between masculinity and sun protection cognitions were significant only among men who did not receive the intervention. Findings suggest that UV photography is a promising sun protection intervention among masculine men.

  10. Neutrinos from WIMP annihilations in the Sun including neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Blennow, Mattias, E-mail: emb@kth.se [Department of Theoretical Physics, School of Engineering Sciences, Royal Institute of Technology (KTH) - AlbaNova University Center, SE-106 91 Stockholm (Sweden); Edsjoe, Joakim, E-mail: edsjo@physto.se [Department of Physics, Stockholm University - AlbaNova University Center, SE-106 91 Stockholm (Sweden); Ohlsson, Tommy, E-mail: tommy@theophys.kth.se [Department of Theoretical Physics, School of Engineering Sciences, Royal Institute of Technology (KTH) - AlbaNova University Center, SE-106 91 Stockholm (Sweden)

    2011-12-15

    The prospects to detect neutrinos from the Sun arising from dark matter annihilations in the core of the Sun are reviewed. Emphasis is placed on new work investigating the effects of neutrino oscillations on the expected neutrino fluxes.

  11. How Can I Protect My Children from the Sun?

    Science.gov (United States)

    ... How Can I Protect My Children from the Sun? Language: English Español (Spanish) Recommend on Facebook Tweet ... other options to prevent UV damage. Too Much Sun Hurts Turning pink? Unprotected skin can be damaged ...

  12. NASA LaRC airborne high spectral resolution lidar aerosol measurements during MILAGRO: observations and validation

    Directory of Open Access Journals (Sweden)

    L. I. Kleinman

    2009-07-01

    Full Text Available The NASA Langley Research Center (LaRC airborne High Spectral Resolution Lidar (HSRL measures vertical profiles of aerosol extinction, backscatter, and depolarization at both 532 nm and 1064 nm. In March of 2006 the HSRL participated in the Megacity Initiative: Local and Global Research Observations (MILAGRO campaign along with several other suites of instruments deployed on both aircraft and ground based platforms. This paper presents high spatial and vertical resolution HSRL measurements of aerosol extinction and optical depth from MILAGRO and comparisons of those measurements with similar measurements from other sensors and model predictions. HSRL measurements coincident with airborne in situ aerosol scattering and absorption measurements from two different instrument suites on the C-130 and G-1 aircraft, airborne aerosol optical depth (AOD and extinction measurements from an airborne tracking sunphotometer on the J-31 aircraft, and AOD from a network of ground based Aerosol Robotic Network (AERONET sun photometers are presented as a validation of the HSRL aerosol extinction and optical depth products. Regarding the extinction validation, we find bias differences between HSRL and these instruments to be less than 3% (0.01 km−1 at 532 nm, the wavelength at which the HSRL technique is employed. The rms differences at 532 nm were less than 50% (0.015 km−1. To our knowledge this is the most comprehensive validation of the HSRL measurement of aerosol extinction and optical depth to date. The observed bias differences in ambient aerosol extinction between HSRL and other measurements is within 15–20% at visible wavelengths, found by previous studies to be the differences observed with current state-of-the-art instrumentation (Schmid et al., 2006.

  13. NASA LaRC airborne high spectral resolution lidar aerosol measurements during MILAGRO: observations and validation

    Directory of Open Access Journals (Sweden)

    R. R. Rogers

    2009-04-01

    Full Text Available The NASA Langley Research Center (LaRC airborne High Spectral Resolution Lidar (HSRL measures vertical profiles of aerosol extinction, backscatter, and depolarization at both 532 nm and 1064 nm. In March of 2006 the HSRL participated in the Megacity Initiative: Local and Global Research Observations (MILAGRO campaign along with several other suites of instruments deployed on both aircraft and ground based platforms. This paper presents high spatial and vertical resolution HSRL measurements of aerosol extinction and optical depth from MILAGRO and comparisons of those measurements with similar measurements from other sensors and model predictions. HSRL measurements coincident with airborne in situ aerosol scattering and absorption measurements from two different instrument suites on the C-130 and G-1 aircraft, airborne aerosol optical depth (AOD and extinction measurements from an airborne tracking sunphotometer on the J-31 aircraft, and AOD from a network of ground based Aerosol Robotic Network (AERONET sun photometers are presented as a validation of the HSRL aerosol extinction and optical depth products. Regarding the extinction validation, we find bias differences between HSRL and these instruments to be less than 3% (0.01 km−1 at 532 nm, the wavelength at which the HSRL technique is employed. The rms differences at 532 nm were less than 50% (0.015 km−1. To our knowledge this is the most comprehensive validation of the HSRL measurement of aerosol extinction and optical depth to date. The observed bias differences in ambient aerosol extinction between HSRL and other measurements is within 15–20% at visible wavelengths, found by previous studies to be the differences observed with current state-of-the-art instrumentation (Schmid et al., 2006.

  14. Measurement of photometric characteristics of daylighting systems

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, S.; Kaase, H. [Technical Univ., Berlin (Germany); Kischkoweit-Lopin, M. [Institut fuer Licht- und Bautechnik an der FH Koln, Cologne (Germany); Scartezzini, J. L.; Michel, L. [Ecole Poytechnuque Federale de Lausanne (Switzerland); Wienold, J.; Apian-Bennewitz, P. [Frauenhofer Institute for Solar Energy Systems, Freiburg (Germany)

    1998-09-01

    The photometric properties of daylighting systems determine the quality of the daylighting in the interior of a building, as well as the possible energy savings by the daylight responsive artificial lighting control systems. Photometric characteristics of daylighting systems and the principles of their measurements in laboratory facilities are described. Characteristics that depend on light incidence and observation of radiation can be measured using integrating sphere photometers or goniophotometers. Luminous transmittance measurements are usually carried out using integrating sphere photometers (cheaper and less time -consuming than measurements with a goniometer). Although the principles involved in the measurement are well understood, results frequently show certain deviations. The various errors that might be responsible for these deviations, whether attributable to the method, or the instrument, or the sample, are also discussed. 10 refs., 8 figs.

  15. Aerosol properties over the Arabian Sea during the north east monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Dulac, F.; Leon, G.F.; Desa, E.

    Knowledge of the variations of the aerosol properties is essential for the development of the satellite atmospheric correction algorithms. The measurements were carried-out during a cruise using a six channel spectral sun photometer at wavelengths...

  16. Blinded by the light the secret life of the sun

    CERN Document Server

    Gribbin, John

    1991-01-01

    An investigation into the secrets and the new scientific developments which are changing our perceptions of the sun. The book tackles such questions as: does the sun breathe?; can it make sound?; is its centre ice-cold? The new research in sun science will alter our perception not only of the sun, but of the whole universe and add to the understanding of how the world works. The author has also written "Hothouse Earth" and "The Hole in the Sky".

  17. Observing the sun a pocket field guide

    CERN Document Server

    Jenkins, Jamey L

    2013-01-01

    A comprehensive solar observing guide for use at the telescope by amateur astronomers at all three levels: beginning, intermediate, and advanced. Users will find invaluable information for identifying features through photos, charts, diagrams in a logical, orderly fashion and then interpreting the observations. Because the Sun is a dynamic celestial body in constant flux, astronomers rarely know for certain what awaits them at the eyepiece. All features of the Sun are transient and sometimes rather fleeting. Given the number of features and the complex life cycles of some solar features, it can be a challenging hobby, and this guide provides all of the guidance necessary to inform observers about the sights and events unfolding before their eyes on the most active and powerful member of our Solar System.

  18. Power producing sun shades; Elproducerende solafskaermninger

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, K.; Soerensen, Henrik; Katic, I.; Schmidt-Petersen, H.; AAroe, D.

    2012-01-15

    Integrating photovoltaics into sun shades takes advantage of the best opportunities to capture and utilize solar energy when the shades are most needed to shield users from solar radiation. The report describes results of a development project for solar shading in the form of broad, horizontal and rotating lamellae with solar cells and an integrated control function that simultaneously is optimized based on energy consumption and thermal and visual indoor climate. The project idea was to meet the needs for effective sun protection in the present office, commercial and public buildings, where glass facades are dominant. The conclusion of the development project is that it rarely would be optimal to integrate solar cells into movable shades. This will normally only be relevant in cases where it is justified by architectural considerations. (LN)

  19. Hierarchical analysis of the quiet Sun magnetism

    CERN Document Server

    Ramos, A Asensio

    2014-01-01

    Standard statistical analysis of the magnetic properties of the quiet Sun rely on simple histograms of quantities inferred from maximum-likelihood estimations. Because of the inherent degeneracies, either intrinsic or induced by the noise, this approach is not optimal and can lead to highly biased results. We carry out a meta-analysis of the magnetism of the quiet Sun from Hinode observations using a hierarchical probabilistic method. This model allows us to infer the statistical properties of the magnetic field vector over the observed field-of-view consistently taking into account the uncertainties in each pixel due to noise and degeneracies. Our results point out that the magnetic fields are very weak, below 275 G with 95% credibility, with a slight preference for horizontal fields, although the distribution is not far from a quasi-isotropic distribution.

  20. Under the Lens: Investigating the Sun's Mysteries

    Science.gov (United States)

    Harwood, William; Klotz, Irene

    2008-11-01

    Sometime around 2012, the waxing 11-year solar cycle once again will reach its peak. Between now and then, magnetically turbulent sunspots, spawned by some still mysterious process, will form near the poles in increasing numbers and migrate toward the Sun's faster-rotating equator in pairs of opposite polarity. Titanic magnetic storms will rage as immense flux tubes rise to the surface in active regions around sunspots and spread out in a boiling sea of electric charge. Magnetic field lines across an enormous range of scales will arc and undulate, rip apart and reconnect, heating the Sun's upper atmosphere and occasionally triggering brilliant flares and multibillion-megaton coronal mass ejections (CMEs) that travel through the solar wind and slam into Earth.