The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
G. Pisani - One of the best experts on this subject based on the ideXlab platform.
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Aerosol‐type‐dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, Albert Ansmann, G. PisaniAbstract:[1] We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios (lidar ratios) and Angstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions (Arctic haze) after long-range transport. In addition, we present particle Angstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET (Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the Angstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
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Aerosol-type-dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research Atmospheres, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, G. PisaniAbstract:We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios ( lidar ratios) and (A) over circle ngstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions ( Arctic haze) after long-range transport. In addition, we present particle (A) over circle ngstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET ( Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the (A) over circle ngstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
Molly E Brown - One of the best experts on this subject based on the ideXlab platform.
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role of surface wind and vegetation cover in multi decadal variations of dust emission in the Sahara and sahel
Atmospheric Environment, 2017Co-Authors: Mian Chin, Lorraine A Remer, Thomas Diehl, Huisheng Bian, Hongbin Yu, Molly E BrownAbstract:Abstract North Africa, the world's largest dust source, is non-uniform, consisting of a permanently arid region (Sahara), a semi-arid region (Sahel), and a relatively moist vegetated region (Savanna), each with very different rainfall patterns and surface conditions. This study aims to better understand the controlling factors that determine the variation of dust emission in North Africa over a 27-year period from 1982 to 2008, using observational data and model simulations. The results show that the model-derived Saharan dust emission is only correlated with the 10-m winds (W10m) obtained from reanalysis data, but the model-derived Sahel dust emission is correlated with both W10m and the Normalized Difference Vegetation Index (NDVI) that is obtained from satellite. While the Saharan dust accounts for 82% of the continental North Africa dust emission (1340–1570 Tg year−1) in the 27-year average, the Sahel accounts for 17% with a larger seasonal and inter-annual variation (230–380 Tg year−1), contributing about a quarter of the transatlantic dust transported to the northern part of South America. The decreasing dust emission trend over the 27-year period is highly correlated with W10m over the Sahara (R = 0.92). Over the Sahel, the dust emission is correlated with W10m (R = 0.69) but is also anti-correlated with the trend of NDVI (R = -0.65). W10m is decreasing over both the Sahara and the Sahel between 1982 and 2008, and the trends are correlated (R = 0.53), suggesting that Saharan/Sahelian surface winds are a coupled system, driving the inter-annual variation of dust emission.
Detlef Müller - One of the best experts on this subject based on the ideXlab platform.
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Aerosol‐type‐dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, Albert Ansmann, G. PisaniAbstract:[1] We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios (lidar ratios) and Angstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions (Arctic haze) after long-range transport. In addition, we present particle Angstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET (Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the Angstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
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Aerosol-type-dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research Atmospheres, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, G. PisaniAbstract:We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios ( lidar ratios) and (A) over circle ngstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions ( Arctic haze) after long-range transport. In addition, we present particle (A) over circle ngstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET ( Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the (A) over circle ngstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
Natalie M Mahowald - One of the best experts on this subject based on the ideXlab platform.
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modeling mineral dust emissions from the Sahara desert using new surface properties and soil database
Journal of Geophysical Research, 2008Co-Authors: B Laurent, B Marticorena, G Bergametti, J F Leon, Natalie M MahowaldAbstract:[1] The present study investigates the mineral dust emissions and the occurrence of dust emission events over the Sahara desert from 1996 to 2001. Mineral dust emissions are simulated over a region extending from 16°N to 38°N and from 19°W to 40°E with a 1/4° × 1/4° spatial resolution. The input parameters required by the dust emission model are surface features data (aerodynamic roughness length, dry soil size distribution and texture for erodible soils), and meteorological surface data (mainly surface wind velocity and soil moisture). A map of the aerodynamic roughness lengths is established based on a composition of protrusion coefficients derived from the POLDER-1 surface products. Soil dry size distribution and texture are derived from measurements performed on soil samples from desert areas, and from a soil map derived from a geomorphologic analysis of desert landscapes. Surface re-analyzed meteorological databases (ERA-40) of the European Centre for Medium range Weather Forecasts (ECMWF) are used. The influence of soil moisture on simulated dust emissions is quantified. The main Saharan dust sources identified during the 6-year simulated period are in agreement with the previous studies based on in situ or satellite observations. The relevance of the simulated large dust sources and point sources ("hot spots") is tested using aerosol indexes derived from satellite observations (TOMS Absorbing Aerosol Index and Infrared Dust Difference Index Meteosat). The Saharan dust emissions simulated from 1996 to 2001 range from 585 to 759 Tg a -1 . The simulations show marked seasonal cycles with a maximum in summer for the western Sahara and in spring for the eastern Sahara. The interannual variability of dust emissions is pronounced in the eastern part of the Sahara while the emissions from the western Sahara are more regular over the studied period. The soil moisture does not noticeably affect the Saharan dust emissions, their seasonal cycle or their interannual variability, but it can partly control and limit the dust emissions in some parts of the northern desert margin, where the precipitation rates are higher. Our simulations also tend to confirm that the Sahara is the major terrestrial source of mineral dust.
Ina Mattis - One of the best experts on this subject based on the ideXlab platform.
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Aerosol‐type‐dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, Albert Ansmann, G. PisaniAbstract:[1] We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios (lidar ratios) and Angstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions (Arctic haze) after long-range transport. In addition, we present particle Angstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET (Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the Angstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
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Aerosol-type-dependent lidar ratios observed with Raman lidar
Journal of Geophysical Research Atmospheres, 2007Co-Authors: Detlef Müller, Ina Mattis, Dietrich Althausen, Ulla Wandinger, Matthias Tesche, G. PisaniAbstract:We summarize our Raman lidar observations which were carried out in Europe, Asia, and Africa during the past 10 years, with focus on particle extinction-to-backscatter ratios ( lidar ratios) and (A) over circle ngstrom exponents. For the first time, we present statistics on lidar ratios for almost all climatically relevant aerosol types solely based on Raman lidar measurements. Sources of continental particles were in North America and Europe, the Sahara, and south and Southeast and east Asia. The North Atlantic Ocean, and the tropical and South Indian Ocean were the sources of marine particles. The statistics are complemented with lidar ratios describing aged forest fire smoke and pollution from polar regions ( Arctic haze) after long-range transport. In addition, we present particle (A) over circle ngstrom exponents for the wavelength range from 355 to 532 nm and from 532 to 1064 nm. We compare our data set of lidar ratios to the recently published AERONET ( Aerosol Robotic Network) lidar ratio climatology. That climatology is based on aerosol scattering modeling in which AERONET Sun photometer observations serve as input. Raman lidar measurements of extinction-to-backscatter ratios of Saharan dust and urban aerosols differ significantly from the numbers obtained with AERONET Sun photometers. There are also differences for some of the (A) over circle ngstrom exponents. Further comparison studies are needed to reveal the reason for the observed differences.
