Arid
DOI10.5194/acp-11-12841-2011
Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: distribution, properties and radiative effects during the 2009 pre-monsoon season
Gautam, R.1,2; Hsu, N. C.2; Tsay, S. C.2; Lau, K. M.2; Holben, B.2; Bell, S.2,3; Smirnov, A.2,4; Li, C.2,5; Hansell, R.2,5; Ji, Q.2,5; Payra, S.6; Aryal, D.7; Kayastha, R.8; Kim, K. M.2,9
通讯作者Gautam, R.
来源期刊ATMOSPHERIC CHEMISTRY AND PHYSICS
ISSN1680-7316
EISSN1680-7324
出版年2011
卷号11期号:24页码:12841-12863
英文摘要

We examine the distribution of aerosols and associated optical/radiative properties in the Gangetic-Himalayan region from simultaneous radiometric measurements over the Indo-Gangetic Plains (IGP) and the foothill/southern slopes of the Himalayas during the 2009 pre-monsoon season. Enhanced dust transport extending from the Southwest Asian arid regions into the IGP, results in seasonal mean (April-June) aerosol optical depths of over 0.6 - highest over Southern Asia. The influence of dust loading is greater over the Western IGP as suggested by pronounced coarse mode peak in aerosol size distribution and spectral single scattering albedo (SSA). Transported dust in the IGP, driven by prevailing westerly airmass, is found to be more absorbing (SSA(550) (nm) <0.9) than the near-desert region in Northwestern (NW) India suggesting mixing with carbonaceous aerosols in the IGP. On the contrary, significantly reduced dust transport is observed over eastern IGP and foothill/elevated Himalayan slopes in Nepal where strongly absorbing haze is prevalent, as indicated by lower SSA (0.85-0.9 at 440-1020 nm), suggesting presence of more absorbing aerosols compared to IGP. Additionally, our observations show a distinct diurnal pattern of aerosols with characteristic large afternoon peak, from foothill to elevated mountain locations, associated with increased upslope transport of pollutants - that likely represent large-scale lifting of absorbing aerosols along the elevated slopes during pre-monsoon season. In terms of radiative impact of aerosols, over the source region of NW India, diurnal mean reduction in solar radiation fluxes was estimated to be 19-23 Wm(-2) at surface (12-15% of the surface solar insolation). Furthermore, based on limited observations of aerosol optical properties during the pre-monsoon period and comparison of our radiative forcing estimates with published literature, there exists a general spatial heterogeneity in the regional aerosol forcing, associated with the absorbing aerosol distribution over northern India, with both diurnal mean surface forcing and forcing efficiency over the IGP exceeding that over Northwestern India. Finally, the role of the seasonal progressive buildup of aerosol loading and water vapor is investigated in the observed net aerosol radiative effect over Northwestern India. The radiative impact of water vapor is found to amplify the net regional aerosol radiative forcing suggesting that the two exert forcing in tandem leading to enhanced surface cooling. It is suggested that water vapor contribution should be taken into account while assessing aerosol forcing impact for this region and other seasonally similar environments.


类型Article
语种英语
国家USA ; India ; Nepal
收录类别SCI-E
WOS记录号WOS:000298667600020
WOS关键词ATMOSPHERIC BROWN CLOUDS ; BLACK CARBON AEROSOLS ; OPTICAL-PROPERTIES ; WATER-VAPOR ; CHEMICAL-COMPOSITION ; ABSORBING AEROSOLS ; INDIAN MONSOON ; ARABIAN SEA ; CLIMATE ; DUST
WOS类目Environmental Sciences ; Meteorology & Atmospheric Sciences
WOS研究方向Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/167238
作者单位1.GESTAR Univ Space Res Assoc, Columbia, MD 21044 USA;
2.NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;
3.Sci Syst & Applicat Inc, Lanham, MD 20706 USA;
4.Sigma Space Corp, Lanham, MD 20706 USA;
5.Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA;
6.Extens Ctr Jaipur, Birla Inst Technol Mesra, Jaipur, Rajasthan, India;
7.Tribhuwan Univ, Kathmandu, Nepal;
8.Kathmandu Univ, Dhulikhel, Nepal;
9.GESTAR Morgan State Univ, Baltimore, MD 21251 USA
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Gautam, R.,Hsu, N. C.,Tsay, S. C.,et al. Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: distribution, properties and radiative effects during the 2009 pre-monsoon season[J],2011,11(24):12841-12863.
APA Gautam, R..,Hsu, N. C..,Tsay, S. C..,Lau, K. M..,Holben, B..,...&Kim, K. M..(2011).Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: distribution, properties and radiative effects during the 2009 pre-monsoon season.ATMOSPHERIC CHEMISTRY AND PHYSICS,11(24),12841-12863.
MLA Gautam, R.,et al."Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: distribution, properties and radiative effects during the 2009 pre-monsoon season".ATMOSPHERIC CHEMISTRY AND PHYSICS 11.24(2011):12841-12863.
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