Rapid response of the East Asian trough to Tibetan Plateau snow cover

Abstract

Tibetan Plateau snow cover (TPSC) has subseasonal variations and rapidly influences the atmosphere. In this study, we present the rapid response of the East Asian trough (EAT) within a week to subseasonal variations in TPSC during the boreal winter. Using snow cover analysis obtained from the daily interactive multisensor snow and ice mapping system and the ERA-Interim reanalysis, a considerable relationship between TPSC and 500-hPa geopotential height anomalies over the downstream EAT region is found. Significant negative (positive) 500-hPa geopotential height anomalies originating from the Tibetan Plateau and moving into the EAT region appear within a week following anomalous positive (negative) TPSC events, which lead to changes in EAT strength. Thus, a significantly enhanced (reduced) intensity of the EAT occurs approximately 5–6 days after increased (decreased) TPSC. Numerical experiments confirm the causality of this relationship. Further analysis of the quasi-geostrophic geopotential height tendency equations in numerical experiments indicates that such EAT variations result from anomalous thermal advection from the Tibetan Plateau forced by TPSC.