A decade of change in aerosol properties over the Indian subcontinent

Dey, Sagnik; Girolamo, Larry Di

doi:10.1029/2011gl048153

Cited by 126 publications

(100 citation statements)

References 23 publications

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“…October. This declining trend is especially pronounced over the Thar desert and northeastern part of the Arabian Sea during June to August as also found by Dey and Di Girolamo (2011) using MISR and Kaskaoutis et al (2011) using MODIS observations. A recent study over northern India has shown that this declining trend is mainly attributed to the extremely large values in 2002 and 2003 (in the beginning of the observation period) favored by absence of precipitation and longer aerosol lifetime.…”

Section: Aerosol Trends Over Southwest Asia and Sistanmentioning

confidence: 64%

“…In spring, the AI and AOD values start to increase, with the Nimbus 7 AI showing an increasing trend. The AOD values during the 2000s exhibit a rather neutral or even slight decreasing trend for all sensors indicating a decrease in dust-aerosol loading over Sistan, as also found over northern India from MISR (Dey and di Girolamo, 2011) and MODIS (Kaskaoutis et al, 2011) observations. Both AOD…”

Section: Multi-year Variation Of Aerosols Over Sistanmentioning

confidence: 83%

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Spatio-temporal variability of dust aerosols over the Sistan region in Iran based on satellite observations

et al. 2013

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Satellite remote sensing provides important observational constraints for monitoring dust life cycle and improving the understanding of its effects on local to global scales. The present work analyses the dust-aerosol patterns over the arid environment of the Sistan region-in southeastern Iran, by means of multiple satellite platforms aiming to reveal the spatiotemporal distribution and trends. The dataset includes records of Aerosol Index (AI) from Total Ozone Mapping Spectrometer (TOMS) and 6-year AI records from the Ozone Monitoring Instrument (OMI) aboard Aura. Moreover, the aerosol optical depth (AOD) is analyzed through 11-year records from Multi-angle Imaging Spectro-Radiometer (MISR) aboard Terra (2000Terra ( -2010 and from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra (2000Terra ( -2007 and Aqua (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011). The main focus is to determine similarities and differences in dust variability over southwest Asia, in general, and the Sistan region, in particular. The results show a marked seasonal cycle with high aerosol loading during summer and lower in winter, while MISR, MODIS and TOMS/OMI observations agree in both terms of monthly and seasonally mean spatial and temporal patterns. The higher aerosol concentrations during summer are interpreted as a result of the combined effect of the seasonal drying of the Hamoun lakes and the strong northerly Levar winds favoring dust erosion from the alluvial deposits in Sistan . After prolonged drought period, the dust-aerosol load over the area has increased in the beginning of the 2000s and decreased after 2004, 2 thereby leading to an overall declining trend during the last decade. Such a trend is absent during the winter period when dust emission over the region is minimal.

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Section: Aerosol Trends Over Southwest Asia and Sistanmentioning

confidence: 64%

Section: Multi-year Variation Of Aerosols Over Sistanmentioning

confidence: 83%

Spatio-temporal variability of dust aerosols over the Sistan region in Iran based on satellite observations

et al. 2013

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“…MISR retrievals have been used to classify particles relating to events such as biomass burning, desert dust, volcanic eruptions, and pollution events (e.g. Liu et al, 2007;Kalashnikova and Kahn, 2008;Dey and Di Girolamo, 2011;Scollo et al, 2012;Guo et al, 2013). The most commonly used satellite product for aerosol information is aerosol optical depth (AOD), the columnar extinction of radiation by atmospheric aerosols.…”

Section: Introductionmentioning

confidence: 99%

Insight into global trends in aerosol composition from 2005 to 2015 inferred from the OMI Ultraviolet Aerosol Index

Hammer

Martin

et al. 2018

Atmos. Chem. Phys.

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Abstract. Observations of aerosol scattering and absorption offer valuable information about aerosol composition. We apply a simulation of the Ultraviolet Aerosol Index (UVAI), a method of detecting aerosol absorption from satellite observations, to interpret UVAI values observed by the Ozone Monitoring Instrument (OMI) from 2005 to 2015 to understand global trends in aerosol composition. We conduct our simulation using the vector radiative transfer model VLI-DORT with aerosol fields from the global chemical transport model GEOS-Chem. We examine the 2005-2015 trends in individual aerosol species from GEOS-Chem and apply these trends to the UVAI simulation to calculate the change in simulated UVAI due to the trends in individual aerosol species. We find that global trends in the UVAI are largely explained by trends in absorption by mineral dust, absorption by brown carbon, and scattering by secondary inorganic aerosol. Trends in absorption by mineral dust dominate the simulated UVAI trends over North Africa, the Middle East, East Asia, and Australia. The UVAI simulation resolves observed negative UVAI trends well over Australia, but underestimates positive UVAI trends over North Africa and Central Asia near the Aral Sea and underestimates negative UVAI trends over East Asia. We find evidence of an increasing dust source from the desiccating Aral Sea that may not be well represented by the current generation of models. Trends in absorption by brown carbon dominate the simulated UVAI trends over biomass burning regions. The UVAI simulation reproduces observed negative trends over central South America and West Africa, but underestimates observed UVAI trends over boreal forests. Trends in scattering by secondary inorganic aerosol dominate the simulated UVAI trends over the eastern United States and eastern India. The UVAI simulation slightly overestimates the observed positive UVAI trends over the eastern United States and underestimates the observed negative UVAI trends over India. Quantitative simulation of the OMI UVAI offers new insight into global trends in aerosol composition.

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“…Kaskaoutis et al (2011) focused on analysis of aerosol load over south Asia using MODIS-Terra AOT data during the period (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009), and found an increasing trend of 10.17 % in AOT. Dey and Di Girolamo (2011) used ten years of MISR observations (March 2000-February 2010, and found seasonal increase in AOT in a range of 0.1-0.4 over the Indian subcontinent due to human activity. Still, it remains a challenging task to retrieve accurate AOTs over land using satellite observations (aerosol retrieval uncertainty: ±0.20 ∼ 0.30 × AOT for TOMS (Torres et al, 2002), ±0.05 ± 0.20 × AOT for MISR (Kahn et al, 2005a, and ±0.05 ± 0.15 × AOT for MODIS (Remer et al, 2008;Levy et al, 2010)) because of the high spatial and temporal variability of the surface contribution, aerosol loading, and aerosol characteristics.…”

Section: Introductionmentioning

confidence: 99%

Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China

et al. 2011

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Abstract. The main purposes of the present paper are not only to investigate linear long-term trends of Aerosol Optical Thickness (AOT) at 443 and 555 nm over regions in Europe and South China, but also to show the uncertainty caused by cloud disturbance in the trend analysis of cloudfree aerosol. These research areas are the densely urbanised and often highly polluted regions. The study uses the Bremen AErosol Retrieval (BAER) and Sea-viewing Wide Field-ofview Sensor (SeaWiFS) data for AOT retrievals in the specified regions from October 1997 to May 2008. In order to validate the individually retrieved AOTs and the corresponding trends, AErosol RObotic NETwork (AERONET) level 2.0 data have been used. The retrieved AOTs were in good agreement with those of AERONET (0.79 ≤ R ≤ 0.88, 0.08 ≤ RMSD ≤ 0.13). The contamination of the aerosol retrievals and/or AERONET observations by thin clouds can significantly degrade the AOT and lead to statistically nonrepresentative monthly-means, especially during cloudy seasons. Therefore an inter-correction method has been developed and applied. The "corrected" trends for both BAER SeaWiFS and AERONET AOT were similar and showed in average a relative difference of ∼25.19 %. In general terms, negative trends (decrease of aerosol loading) were mainly observed over European regions, with magnitudes up to −0.00453 and −0.00484 yr −1 at 443 and 555 nm, respectively. In contrast, the trend in Pearl River Delta was positive, most likely attributed to rapid urbanization and industrialization. The magnitudes of AOT increased by +0.00761 and +0.00625 yr −1 respectively at 443 and 555 nm.

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A decade of change in aerosol properties over the Indian subcontinent

Cited by 126 publications

References 23 publications

Spatio-temporal variability of dust aerosols over the Sistan region in Iran based on satellite observations

Spatio-temporal variability of dust aerosols over the Sistan region in Iran based on satellite observations

Insight into global trends in aerosol composition from 2005 to 2015 inferred from the OMI Ultraviolet Aerosol Index

Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China

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