Abstract
We use the combined Dark Target/Deep Blue aerosol optical depth (AOD) satellite product of the moderate-resolution imaging spectroradiometer (MODIS) collection 6 to study trends over the Middle East between 2000 and 2015. Our analysis corroborates a previously identified positive AOD trend over large parts of the Middle East during the period 2001 to 2012. We relate the annual AOD to precipitation, soil moisture and surface winds to identify regions where these attributes are directly related to the AOD over Saudi Arabia, Iraq and Iran. Regarding precipitation and soil moisture, a relatively small area in and surrounding Iraq turns out to be of prime importance for the AOD over these countries. Regarding surface wind speed, the African Red Sea coastal area is relevant for the Saudi Arabian AOD. Using multiple linear regression we show that AOD trends and interannual variability can be attributed to soil moisture, precipitation and surface winds, being the main factors controlling the dust cycle. Our results confirm the dust driven AOD trends and variability, supported by a decreasing MODIS-derived Ångström exponent and a decreasing AERONET-derived fine mode fraction that accompany the AOD increase over Saudi Arabia. The positive AOD trend relates to a negative soil moisture trend. As a lower soil moisture translates into enhanced dust emissions, it is not needed to assume growing anthropogenic aerosol and aerosol precursor emissions to explain the observations. Instead, our results suggest that increasing temperature and decreasing relative humidity in the last decade have promoted soil drying, leading to increased dust emissions and AOD; consequently an AOD increase is expected due to climate change.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5063-5073 |
| Number of pages | 11 |
| Journal | Atmospheric Chemistry and Physics |
| Volume | 16 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 22 2016 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): URF/1/2180-01
Acknowledgements: The research reported in this publication has received funding from King Abdullah University of Science and Technology (KAUST). For computer time, the resources of the KAUST Supercomputing Laboratory were used by the KAUST researchers. K. Klingmüller is supported by the KAUST CRG3 grant URF/1/2180-01 Combined Radiative and Air Quality
Effects of Anthropogenic Air Pollution and Dust over the Arabian Peninsula.
