Impacts of Interdecadal Variability of Circulation and Winter Monsoon on Winter Snowfall over the Tibetan Plateau

The relationships of the general circulation and East Asian winter monsoon (EAWM) index anomalies e.g., the East Asian trough location index (CW), Siberian High intensity index (SH) with the winter snowfall (WS) over the Tibetan Plateau (TP), as well as the interdecadal characteristics, during 1961-2010, are analyzed. The results show that: 1) The abnormalities of winter planetary waves in the Northern Hemisphere (NH) impact on the WS over the TP on interdecadal scales; 2) The variations of the planetary wave pattern in the NH, “Three Troughs/Ridges in winter”, are the background circulation for the WS change over the TP on interdecadal scales; 3) The WS over the TP and the EAWM indices indicate significant correlation on interdecadal scales; 4) The WS increases over the TP with a decreasing trend of the EAWM during 1961-1986; 5) The WS over the TP, the CW and SH, all show an abrupt change around 1986. After this abrupt change, the intensity of the winter “three troughs” pattern demonstrates a stronger variation, while the amount of WS over the TP declines.