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Observed radiative cooling over the Tibetan Plateau for the past three decades driven by snow cover‐induced surface albedo anomaly
Author(s) -
Chen Xiaona,
Long Di,
Hong Yang,
Liang Shunlin,
Hou Aizhong
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd026652
Subject(s) - albedo (alchemy) , snow , atmospheric sciences , environmental science , radiative forcing , shortwave radiation , plateau (mathematics) , northern hemisphere , climatology , radiative transfer , shortwave , radiative cooling , radiative flux , aerosol , geology , meteorology , geography , radiation , physics , art , mathematical analysis , mathematics , quantum mechanics , performance art , art history
Seasonal snow cover on the Tibetan Plateau (TP) is a sensitive indicator of climate change. Unlike the decreasing snow cover extent and associated weakening of radiative cooling effects for the Northern Hemisphere during recent decades reported by previous studies, snow cover variability over the TP and its impact on the energy budget remain largely unknown. We defined the snow cover‐induced radiative forcing (S n RF) as the instantaneous perturbation to Earth's shortwave radiation at the top of the atmosphere (TOA) induced by the presence of snow cover. Here using satellite observations and a radiative kernel approach, we found slightly enhanced S n RF, i.e., a radiative cooling effect on the TP during the past three decades (1982–2014). However, this cooling effect weakened during 2001–2014 because of reduced snow cover at a rate of −0.61% decade −1 and land surface albedo at a rate of −0.72% decade −1 . Changes in snow cover fraction are highly correlated with anomalies in land surface albedo ( a s ) over the TP both spatially and temporally. Moreover, the S n RF is closely related to the direct observation of TOA shortwave flux anomalies ( R 2 = 0.54, p = 0.004) over the TP during 2001–2014. Despite the insignificant interannual variability in S n RF, its intra‐annual variability has intensified driven mostly by enhanced S n RF during the snow accumulation season but weakened S n RF during the melt season, indicating greater energy release during the transition between accumulation and melt seasons. This may pose a great challenge to snow meltwater use and flood prediction for transboundary rivers originating from the TP, such as the Brahmaputra River basin.