Characteristics Of Aerosol Properties Over The West Asia

The characteristic of aerosol optical properties and mass concentration over the West Asia are analyzed using 2010-2017 AERONET and 2003-2018 MODIS and MERRA-2 data.Based on 10 AERONET sites over the West Asia,the variation characteristic of aerosol multiple properties are studied.The aerosol properties and mass concentration over the region also are studied using MODIS and MERRA-2.The results show that the average of aerosol optical depth(AOD),absorption aerosol optical depth(AAOD),?ngstr?m exponent(α)and single scattering albedo(SSA)at the West Asia sites are 0.245±0.094 、0.030±0.006、0.889±0.247 and 0.918±0.016,respectively,and the VSD are bio-modal.In generally,higher AOD occur in in spring and summer,while lower AOD occur in autumn and winter.The minimum of α and peak concentration of coarse particles are both found in spring.At the Middle East sites,higher AAOD occur in summer and autumn,while lower AAOD occur in winter and spring.Higher SSA are found in spring and summer,while lower SSA in autumn and winter.But at the Mediterranean sites,higher AAOD occur in winter and spring,while lower in summer and autumn.Higher SSA are found in summer and autumn,while lower in winter and spring.The diurnal variation of annual mean AOD at the Middle East sites is much obvious than those at the Mediterranean sites.Among them,the AOD at desert sites is higher in morning and nightfall,while lower at noon.TEP site shows a remarkable decreasing trend of α in recent years.DD and MI are the two main aerosol types at Middle East sites,while BB/UI and DP are the two main aerosol types at Mediterranean Sites.From MODIS data,AOD over the Persian Gulf,Oman and Red Sea are higher during four seasons.And the AOD over the Red Sea in summer are the highest.From MODIS data,α in the middle part of the Middle East is the lowest,while the north of the Mediterranean region is the highest during different seasons.The area of low α gets to smaller from spring to winter,while the area of high α becomes wider from autumn to winter,especially widest in December.From 2003 to 2018,AOD over the West Asia is rising with annual increase of 0.004,while α is decreasing with annual decline of-0.011.It is related to increasing dust events.From MERRA-2 data,the characteristics of surface total aerosol and dust aerosol mass concentration are similar,which is higher in spring and summer while lower in autumn and winter.The high values concentrate on the east and southeast of Arabian Peninsula.The black carbon is higher in autumn and winter,while lower in spring and summer.The high values focus on the Tehran(capital of Iran)and Baghdad(capital of Iraq).In general,the organic carbon is higher in summer and autumn,while lower in winter and spring.The high values focus on Basra in Iraq.The surface sulfate mass concentration is higher in summer and autumn,while lower in winter and spring.And its high values focus on Persian Gulf where petroleum industry is blooming.As to annual variation,black carbon and organic carbon both increase obviously while the trend of other type of aerosols are not obvious.The increase of black carbon and organic carbon might be attributed to the increasing use of fossil energy due to rapid growth of population.