Possible impacts of vegetation cover increment on the relationship between winter snow cover anomalies over the Third Pole and summer precipitation in East Asia

Abstract

Snow cover over the Tibetan Plateau (TP)–the Third Pole of the earth has been recognized as a reliable signal of summer floods or droughts in East Asia (EA). The distribution of snow cover can be influenced by vegetation, however, the impacts of changes in cover of non-growing season vegetation–withered grass stem over TP on the climatic effects of snow cover remains poorly understood. Here, we showed that the relationship between TP winter snow cover (TPWSC) and EA summer precipitation (EASP) strengthened starting in the early 1990s but weakened after the early 2000s. The weakening of the TPWSC–EASP relationship was linked to the effects of vegetation cover increment (VCI) on winter and spring snow cover over the TP. A possible mechanism behind this linkage is that VCI leads to a shortened persistence of TPWSC anomalies and weakened surface diabatic heating anomalies in spring. Consequently, the influences of TP thermal forcing on the downstream atmospheric circulation in summer were altered, resulting in a different pattern of EASP anomalies. These findings highlight the importance of snow—vegetation feedback and its potential to alter the effectiveness of snow cover in seasonal climate prediction.