Connection between the North Atlantic sea surface temperature and the late autumn snow cover anomalies over the central Tibetan Plateau

Abstract

Many studies have investigated the effects of the snow anomalies over the Tibetan Plateau (TP), yet the original causes of these anomalies are not fully understood. In this study, we explore the possible connection between the late autumn (November) central TP snow cover anomalies and the monthly sea surface temperature (SST) over the North Atlantic (NA) in autumn and find significant correlations over the mid-latitude NA during October and November. By analyzing the air-sea interaction over the NA, we show that a well-organized horseshoe-like SST anomaly pattern coupled with a surface anomalous anticyclone centered over the mid-latitude NA in October and its persistence in November may play a key role in the November central TP snow cover anomalies. Such an October surface anomalous anticyclone could effectively result in the surface turbulent heat flux anomalies via the surface wind-induced horizontal temperature advection, which is conducive to the formation of the horseshoe-like SST anomalies over the mid-latitude NA. The resultant anomalous SST pattern could further contribute to a North Atlantic Oscillation (NAO)-like pattern in November and stimulate the wave trains eastward to the TP. The anomalous anticyclone (cyclone) associated with the wave trains to the southwest (north) of the TP suppresses the precipitation over the central TP and thus reduces the local snow cover. The atmospheric circulation responses to the persistent NA-SST anomalies are well validated by the numerical experiments. The above result might help to predict the condition of the central TP snow cover anomalies in November, one month ahead.