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A. Smirnov - One of the best experts on this subject based on the ideXlab platform.
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analysis of approaches to modeling the annual and spectral behaviors of atmospheric Aerosol Optical Depth in siberia and primorye
Atmospheric and Oceanic Optics, 2015Co-Authors: S M Sakerin, B N Holben, D M Kabanov, S V Nikolashkin, Yu S Turchinovich, G I Kornienko, S A Beresnev, V A Poddubny, M A Tashchilin, A. SmirnovAbstract:Data of multiyear sun photometer measurements in the Asian part of Russia are used to analyze the issues regarding the modeling of annual and spectral behaviors of the atmospheric Aerosol Optical Depth (AOD) based on separation of the contributions of fine and coarse Aerosols. The specific features of the spatial distribution and seasonal variations in AOD characteristics in different regions are discussed; and a three-parameter model of annual behavior of spectral AOD in the range 0.34–4 μm for Western Siberia (Tomsk) is suggested.
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on results of studies of atmospheric Aerosol Optical Depth in arctic regions
Atmospheric and Oceanic Optics, 2014Co-Authors: S M Sakerin, B N Holben, D M Kabanov, Vladimir F Radionov, Dmitry G Chernov, Yu S Andreev, S V Nikolashkin, A N Prakhov, Yu S Turchinovich, A. SmirnovAbstract:We discuss the characteristics of the spectral Aerosol Optical Depth (AOD) of the atmosphere measured using sun photometers in high-latitude regions (Spitsbergen, Tiksi, Yakutsk). The seasonal variations are characterized by a decrease in AOD from spring to fall by approximately a factor of 2 in Yakutia and by a factor of 1.5 in the region of Spitsbergen. It is shown that the high selectivity of the spectral AOD dependence in warm period (with Angstrom parameters varying from 1.3 to 1.8) was caused by low content of coarsely dispersed Aerosol. Multiyear data of MODIS satellite observations are used to estimate the spatial distribution of turbidity; it is shown that satellite observations systematically overestimate AOD over Arctic seas.
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results of spectral measurements of atmospheric Aerosol Optical Depth with sun photometers in the 58th russian antarctic expedition
Atmospheric and Oceanic Optics, 2014Co-Authors: S M Sakerin, B N Holben, D M Kabanov, Vladimir F Radionov, A N Prakhov, Yu S Turchinovich, N I Vlasov, K E Lubolesnichenko, A. SmirnovAbstract:We discuss the specific features of the spatiotemporal variations in the atmospheric Aerosol Optical Depth (AOD) measured during the 58th Russian Antarctic Expedition on board RVs “Akademik Fedorov” and “Akademik Tryoshnikov” and at the Mirny station. It is shown that the main feature of the spatiotemporal AOD distribution over ocean in the Southern Hemisphere is the linear latitudinal decrease of AOD from 0.15 at the equator to 0.025 near Antarctica. We indicate that the low AOD level in Antarctica (0.022 ± 0.005) has persisted for the last 17 years.
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assessment of error in Aerosol Optical Depth measured by aeronet due to Aerosol forward scattering
Geophysical Research Letters, 2012Co-Authors: Alexander Sinyuk, D M Giles, J S Schafer, Ilya Slutsker, A. Smirnov, Brent N. Holben, M G SorokinAbstract:[1] 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.
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effect of wind speed on Aerosol Optical Depth over remote oceans based on data from the maritime Aerosol network
Atmospheric Measurement Techniques, 2012Co-Authors: A. Smirnov, B N Holben, S M Sakerin, A M Sayer, N C Hsu, Andreas Macke, Norman B Nelson, Yann Courcoux, Timothy J Smyth, Peter CrootAbstract:The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. The MAN archive provides a valuable resource for Aerosol stud- ies in maritime environments. In the current paper we inves- tigate correlations between ship-borne Aerosol Optical Depth (AOD) and near-surface wind speed, either measured (on- board or from satellite) or modeled (NCEP). According to our analysis, wind speed influences columnar Aerosol Optical Depth, although the slope of the linear regression between AOD and wind speed is not steep ( 0.004-0.005), even for strong winds over 10 m s 1 . The relationships show signif- icant scatter (correlation coefficients typically in the range 0.3-0.5); the majority of this scatter can be explained by the uncertainty on the input data. The various wind speed sources considered yield similar patterns. Results are in good agreement with the majority of previously published relationships between surface wind speed and ship-based or satellite-based AOD measurements. The basic relationships are similar for all the wind speed sources considered; how- ever, the gradient of the relationship varies by around a factor of two depending on the wind data used.
B N Holben - One of the best experts on this subject based on the ideXlab platform.
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analysis of approaches to modeling the annual and spectral behaviors of atmospheric Aerosol Optical Depth in siberia and primorye
Atmospheric and Oceanic Optics, 2015Co-Authors: S M Sakerin, B N Holben, D M Kabanov, S V Nikolashkin, Yu S Turchinovich, G I Kornienko, S A Beresnev, V A Poddubny, M A Tashchilin, A. SmirnovAbstract:Data of multiyear sun photometer measurements in the Asian part of Russia are used to analyze the issues regarding the modeling of annual and spectral behaviors of the atmospheric Aerosol Optical Depth (AOD) based on separation of the contributions of fine and coarse Aerosols. The specific features of the spatial distribution and seasonal variations in AOD characteristics in different regions are discussed; and a three-parameter model of annual behavior of spectral AOD in the range 0.34–4 μm for Western Siberia (Tomsk) is suggested.
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on results of studies of atmospheric Aerosol Optical Depth in arctic regions
Atmospheric and Oceanic Optics, 2014Co-Authors: S M Sakerin, B N Holben, D M Kabanov, Vladimir F Radionov, Dmitry G Chernov, Yu S Andreev, S V Nikolashkin, A N Prakhov, Yu S Turchinovich, A. SmirnovAbstract:We discuss the characteristics of the spectral Aerosol Optical Depth (AOD) of the atmosphere measured using sun photometers in high-latitude regions (Spitsbergen, Tiksi, Yakutsk). The seasonal variations are characterized by a decrease in AOD from spring to fall by approximately a factor of 2 in Yakutia and by a factor of 1.5 in the region of Spitsbergen. It is shown that the high selectivity of the spectral AOD dependence in warm period (with Angstrom parameters varying from 1.3 to 1.8) was caused by low content of coarsely dispersed Aerosol. Multiyear data of MODIS satellite observations are used to estimate the spatial distribution of turbidity; it is shown that satellite observations systematically overestimate AOD over Arctic seas.
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results of spectral measurements of atmospheric Aerosol Optical Depth with sun photometers in the 58th russian antarctic expedition
Atmospheric and Oceanic Optics, 2014Co-Authors: S M Sakerin, B N Holben, D M Kabanov, Vladimir F Radionov, A N Prakhov, Yu S Turchinovich, N I Vlasov, K E Lubolesnichenko, A. SmirnovAbstract:We discuss the specific features of the spatiotemporal variations in the atmospheric Aerosol Optical Depth (AOD) measured during the 58th Russian Antarctic Expedition on board RVs “Akademik Fedorov” and “Akademik Tryoshnikov” and at the Mirny station. It is shown that the main feature of the spatiotemporal AOD distribution over ocean in the Southern Hemisphere is the linear latitudinal decrease of AOD from 0.15 at the equator to 0.025 near Antarctica. We indicate that the low AOD level in Antarctica (0.022 ± 0.005) has persisted for the last 17 years.
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global and regional evaluation of over land spectral Aerosol Optical Depth retrievals from seawifs
Atmospheric Measurement Techniques, 2012Co-Authors: B N Holben, A M Sayer, C Bettenhausen, Myeongjae Jeong, Junyong ZhangAbstract:Abstract. This study evaluates a new spectral Aerosol Optical Depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72% of matchups fall within an expected absolute uncertainty of 0.05 + 20% (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997–2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or Optically-thick cases of absorbing Aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.
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global and regional evaluation of over land spectral Aerosol Optical Depth retrievals from seawifs
Atmospheric Measurement Techniques, 2012Co-Authors: B N Holben, A M Sayer, N C Hsu, C Bettenhausen, Myeongjae Jeong, Jianglong ZhangAbstract:Abstract. This study evaluates a new spectral Aerosol Optical Depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72% of matchups fall within an expected absolute uncertainty of 0.05 + 20% (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997–2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or Optically-thick cases of absorbing Aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.
A M Sayer - One of the best experts on this subject based on the ideXlab platform.
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global and regional evaluation of over land spectral Aerosol Optical Depth retrievals from seawifs
Atmospheric Measurement Techniques, 2012Co-Authors: B N Holben, A M Sayer, N C Hsu, C Bettenhausen, Myeongjae Jeong, Jianglong ZhangAbstract:Abstract. This study evaluates a new spectral Aerosol Optical Depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72% of matchups fall within an expected absolute uncertainty of 0.05 + 20% (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997–2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or Optically-thick cases of absorbing Aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.
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global and regional evaluation of over land spectral Aerosol Optical Depth retrievals from seawifs
Atmospheric Measurement Techniques, 2012Co-Authors: B N Holben, A M Sayer, C Bettenhausen, Myeongjae Jeong, Junyong ZhangAbstract:Abstract. This study evaluates a new spectral Aerosol Optical Depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72% of matchups fall within an expected absolute uncertainty of 0.05 + 20% (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997–2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or Optically-thick cases of absorbing Aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.
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effect of wind speed on Aerosol Optical Depth over remote oceans based on data from the maritime Aerosol network
Atmospheric Measurement Techniques, 2012Co-Authors: A. Smirnov, B N Holben, S M Sakerin, A M Sayer, N C Hsu, Andreas Macke, Norman B Nelson, Yann Courcoux, Timothy J Smyth, Peter CrootAbstract:The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. The MAN archive provides a valuable resource for Aerosol stud- ies in maritime environments. In the current paper we inves- tigate correlations between ship-borne Aerosol Optical Depth (AOD) and near-surface wind speed, either measured (on- board or from satellite) or modeled (NCEP). According to our analysis, wind speed influences columnar Aerosol Optical Depth, although the slope of the linear regression between AOD and wind speed is not steep ( 0.004-0.005), even for strong winds over 10 m s 1 . The relationships show signif- icant scatter (correlation coefficients typically in the range 0.3-0.5); the majority of this scatter can be explained by the uncertainty on the input data. The various wind speed sources considered yield similar patterns. Results are in good agreement with the majority of previously published relationships between surface wind speed and ship-based or satellite-based AOD measurements. The basic relationships are similar for all the wind speed sources considered; how- ever, the gradient of the relationship varies by around a factor of two depending on the wind data used.
T F Eck - One of the best experts on this subject based on the ideXlab platform.
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nocturnal Aerosol Optical Depth measurements with a small aperture automated photometer using the moon as a light source
Journal of Atmospheric and Oceanic Technology, 2011Co-Authors: Timothy A Berkoff, Mikail Sorokin, Tom Stone, T F Eck, R M Hoff, Ellsworth J Welton, Brent N. HolbenAbstract:AbstractA 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...
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high Aerosol Optical Depth biomass burning events a comparison of Optical properties for different source regions
Geophysical Research Letters, 2003Co-Authors: J S Schafer, A. Smirnov, T F Eck, B N Holben, N T Oneill, Jeffrey S Reid, Oleg DubovikAbstract:Received 29 May 2003; revised 8 September 2003; accepted 17 September 2003; published 21 October 2003. [1] The Optical properties of Aerosols such as smoke from biomass burning vary due to aging processes and these particles reach larger sizes at high concentrations. We compare the spectra of Aerosol Optical Depth (ta), columnintegrated volume size distributions, refractive indices, and single scattering albedo retrieved from AERONET observations for four selected events of very high smoke Optical Depth (ta � 2 at 500 nm). Two case studies are from tropical biomass burning regions (Brazil and Zambia) and two are cases of boreal forest and peat fire smoke transported long distances to sites in the US and Moldova. Smoke properties for these extreme events can be significantly different from those reported in more typical plumes. In particular, large differences in smoke fine mode particle radius (� 0.17 to 0.25 mm) and single scattering albedo (� 0.88 to 0.99 at 440 nm) were observed as a result of differences in fuels burned, combustion phase, and aging. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation. Citation: Eck, T. F., B. N. Holben, J. S. Reid, N. T. O’Neill, J. S. Schafer, O. Dubovik, A. Smirnov, M. A. Yamasoe, and P. Artaxo, High Aerosol Optical Depth biomass burning events: A comparison of Optical properties for different source regions, Geophys. Res. Lett., 30(20), 2035, doi:10.1029/ 2003GL017861, 2003.
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diurnal variability of Aerosol Optical Depth observed at aeronet Aerosol robotic network sites
Geophysical Research Letters, 2002Co-Authors: Ilya Slutsker, A. Smirnov, T F Eck, B N Holben, B Chatenet, R T PinkerAbstract:[1] Diurnal variability of Aerosol Optical Depth is important for various applications, including satellite Aerosol data validation, radiative forcing computations, studies of Aerosol interaction with humidity and clouds, and also public health. Aerosol Optical Depth measurements acquired through the ground-based Aerosol Robotic Network are analyzed. Analysis of the diurnal cycle over major urban/industrial areas within the network showed a prevailing pattern of the Optical Depth increase by 10–40% during the day at most sites. Diurnal variability range is <10% over various sites where dust Aerosol is a major contributor to Optical Depth. Sites in southern Africa influenced by distant sources of biomass burning Aerosol show no diurnal cycle, while the presence of local sources causes a diurnal trend with a maximum Aerosol loading observed in the afternoon hours. Over oceans, because of the very low Optical Depth, even 20% departure from the daily average is practically within the measurement uncertainty.
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an emerging ground based Aerosol climatology Aerosol Optical Depth from aeronet
Journal of Geophysical Research, 2001Co-Authors: B N Holben, Ilya Slutsker, A. Smirnov, T F Eck, D Tanre, Nader Abuhassan, W W Newcomb, J S SchaferAbstract:Long-term measurements by the AERONET program of spectral Aerosol Optical Depth, precipitable water, and derived Angstrom exponent were analyzed and compiled into an Aerosol Optical properties climatology. Quality assured monthly means are presented and described for 9 primary sites and 21 additional multiyear sites with distinct Aerosol regimes representing tropical biomass burning, boreal forests, midlatitude humid climates, midlatitude dry climates, oceanic sites, desert sites, and background sites. Seasonal trends for each of these nine sites are discussed and climatic averages presented.
A Tarussov - One of the best experts on this subject based on the ideXlab platform.
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Aerosol Optical Depth over canada and the link with synoptic air mass types
Journal of Geophysical Research, 1996Co-Authors: A. Smirnov, N T Oneill, Alain Royer, A Tarussov, B McarthurAbstract:Aerosol Optical Depth measurements acquired through the Canadian sunphotometer network were statistically analyzed for the 1987-1992 period in order to investigate spatial and temporal commonalities between the member stations. Four stations were chosen to yield a spatially representative sampling of atmospheric Optical conditions across Canada (East Coast, eastern continental, western continental, and West Coast). All the stations were located in rural, local pollution free areas. The results of Aerosol Optical Depth measurements showed significant differences between eastern and western Canadian stations. The effect of the Pinatubo volcanic eruption was clearly seen in the measurements acquired at Sable Island, Nova Scotia. Air mass relationships for the four stations sampled demonstrated the relevance of applying air mass classification criteria to the analysis and discrimination of atmospheric Optical Depth. Knowledge of the seasonal trend combined with information concerning air mass type enables a coarse a priori estimation of Aerosol Optical Depth in the absence of traditional Optical data. SynOptical air mass analysis facilitates the understanding of the mechanisms involved in the seasonal variations of Aerosol Optical Depth and yields useful information about the atmospheric Optical state. The relevance of the synOptical air mass approach was demonstrated in one particular case : a seasonal Aerosol Optical Depth trend for Arctic air masses was observed for the three sunphotometer stations which regularily experience this type of air mass.
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Aerosol Optical Depth over the oceans analysis in terms of synoptic air mass types
Journal of Geophysical Research, 1995Co-Authors: A. Smirnov, N T Oneill, Y Villevalde, Alain Royer, A TarussovAbstract:The results of spectral Aerosol Optical Depth measurements in the Pacific Ocean, Baltic Sea, and North Atlantic are considered with regard to air mass types. It is found that the Optical properties of continental and maritime air mass types differ significantly for the data employed in this study. A synOptical air mass context was also employed in demonstrating the correlation between near infrared Aerosol Optical Depth τa(1640 nm) and wind speed as well as for investigations into the relationship between deck level relative humidity and the Aerosol Optical Depth at 550 nm. Simulations, employing well-known Aerosol parameterization models, of the Aerosol Optical Depth spectra for various air mass types show good agreement with the experimental results in the visible and near infrared range.