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Long-term (2008–2018) aerosol properties and radiative effect at high-altitude sites over western trans-Himalayas

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dc.contributor.author Dumka, U. C
dc.contributor.author Shantikumar, N. S
dc.contributor.author Kaskaoutis, D. G
dc.contributor.author Madhavan, B. L
dc.contributor.author Song, H. -J
dc.contributor.author Angchuk, D
dc.contributor.author Jorphail, S
dc.date.accessioned 2021-02-24T11:24:53Z
dc.date.available 2021-02-24T11:24:53Z
dc.date.issued 2020-09-10
dc.identifier.citation Science of The Total Environment, Vol. 734, 139354 en_US
dc.identifier.issn 0048-9697
dc.identifier.uri http://hdl.handle.net/2248/7667
dc.description Restricted Access © Elsevier B.V. https://doi.org/10.1016/j.scitotenv.2020.139354 en_US
dc.description.abstract Analysis of the climatology of aerosol properties is performed over Hanle (4500 m) and Merak (4310 m), two remote-background sites in the western trans-Himalayas, based on eleven years (2008–2018) of sun/sky radiometer (POM-01, Prede) measurements. The two sites present very similar atmospheric conditions and aerosol properties allowing us to examine them as continuous single-data series. The annual average aerosol optical depth at 500 nm (AOD500) is 0.04 ± 0.03, associated with an Ångström exponent (AE440–870) of 0.58 ± 0.35 and a single scattering albedo (SSA500) of 0.95 ± 0.05. AOD500 exhibits higher values in May (~0.07) and lower in winter (~0.03), while AE400–870 minimizes in spring, indicating influence by coarse-mode dust aerosols, either emitted regionally or long-range transported. The de-convolution of AOD500 into fine and coarse modes justifies the aerosol seasonality and sources, while the marginal diurnal variation in all aerosol properties reveals a weak influence from local sources, except for some few aerosol episodes. The aerosol-volume size distribution presents a mode value at ~10 μm with secondary peaks at accumulation (~ 2 μm) and fine modes (~0.03 μm) and low variability between the seasons. A classification of the aerosol types based on the fine-mode fraction (FMF) vs. SSA500 relationship reveals the dominance of aerosols in the FMF range of 0.4–0.6, characterized as mixed (39%), followed by fine aerosols with high scattering efficiency (26%), while particles related to dust contribute ~21%, with low fractions of fine-absorbing aerosols (~13%). The aerosol radiative forcing (ARF) estimates reveal a small cooling effect at the top of the atmosphere (−1.3 Wm−2), while at the surface, the ARF ranges from −2 Wm−2 to −6 Wm−2 on monthly basis. The monthly-mean atmospheric radiative forcing (~1 to 4 Wm−2) leads to heating rates of 0.04 to 0.13 K day−1. These ARF values are higher than the global averages and may cause climate implications over the trans-Himalayan region. en_US
dc.language.iso en en_US
dc.publisher Elsevier B. V en_US
dc.subject Aerosol optical properties en_US
dc.subject Aerosol size distribution en_US
dc.subject Aerosol types en_US
dc.subject Aerosol radiative forcing en_US
dc.subject High-altitude site en_US
dc.subject Trans-Himalayas en_US
dc.title Long-term (2008–2018) aerosol properties and radiative effect at high-altitude sites over western trans-Himalayas en_US
dc.type Article en_US


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