Investigating evolution of dust events in the Mesopotamian region during 2001 to 2012 by using MODIS and GLDAS data sets

摘要

The Iran plateau is located on the earth dust belt. It always has been subject to different dust activities and dust storms that mostly had been originated from dust sources which are located outside of the plateau. Recently we reported that the Mesopotamian region is responsible for more than 80 percent of observed dust events in Northwest Iran. In this work we have used the available aerosol optical dept (AOD) on the MODIS deep blue and the surface soil moisture data (SM) extracted from GLDAS version-1 data set, to look over the evolutions of dust activities and variations of soil moisture in the Mesopotamian region during 2001 to 2012. Recorded monthly values of AOD indicate that most of the annual dust activities had been occurred during April to July but the soil moisture had had its maximum values during December to March. During the considered period of time in this study, dust activities in Northern Mesopotamian area (centered about 35 E, 42 N) have been strengthened considerably and the center of dust activities has been moved about 0.5 degrees to North and the same amount to East. Looking to the annual trend of the AOD (SM) averaged over the months April, May, Jun and July (December, January, February and March), a trend of ～0.030 ± 0.004 (～0.033 ± 0.002 kg/m~2) per year has been observed for the mentioned time span. Also temporal correlation between annual values of obtained AOD and SM has been investigated in this work. It is found that a strong negative correlation exist between these two parameters and its minimum value (-0.7) occurs when both AOD and soil moisture have been measured in the same year.