Abstract
The present study investigates the impacts of autumn-winter Tibetan Plateau (TP) snow cover anomalies on the interannual variability of the East Asian winter monsoon (EAWM). It is found that the northern component of EAWM is significantly associated with October-November-December-January (ONDJ) snow cover anomalies over the eastern TP, whereas the TP snow cover changes have little impact on the southern component of EAWM. However, the relationship of the northern component of EAWM to ONDJ TP snow cover experienced an obvious change in the mid-1990s. During 1979–1998, due to the high persistence of TP snow anomalies from autumn to winter, extensive ONDJ TP snow cover anomalies have a prominent influence on atmospheric circulation over Asia and the North Pacific, with more TP snow cover followed by an enhanced Siberian high and a deepened Aleutian low in winter, resulting in stronger EAWM. During 1999–2016, TP snow cover anomalies have a weak persistence. The atmospheric circulation anomalies display a different distribution. As such, there is a weak connection between the northern component of EAWM and the TP snow cover anomalies during this period.
Highlights
The Tibetan Plateau (TP) is the highest plateau on earth with an average altitude over 4,000 m above sea level
The present study investigates the impacts of the autumn-winter TP snow cover anomalies on the two components of the EAWM variability on the interannual time scale
A close relationship is identified between the ONDJ snow cover anomalies in the eastern TP and the northern component of the EAWM variability
Summary
The Tibetan Plateau (TP) is the highest plateau on earth with an average altitude over 4,000 m above sea level. The snow cover anomalies over the TP can influence surface air temperature (SAT) variations over North America (e.g., Lin and Wu 2011; Qian et al, 2019; Wang et al, 2020), but the linkage. Following Chen et al (2014a), we used area-mean 1000hPa meridional wind anomalies in December-January-February (DJF) over the regions of 10°–25°N, 105°–135° E (hereinafter, Sindex) and 35°–55°N, 110°–125°E (hereinafter, Nindex) to represent the southern and northern components of the EAWM variability, respectively. Note that these two indices have been multiplied by -1 so that a positive (negative) value of the index corresponds to a strong (weak) EAWM. SH denotes sensible heat flux at the surface, Rnet refers to the net radiation in the atmospheric column, and LP represents the condensation-released latent heat
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