Response of summer rainfall over China to spring snow anomalies over Siberia in the NCEP CFSv2 reforecast

Abstract

Predictions of the snow water equivalent (SWE) over Siberia in spring (March–April–May) and its relationship with summer (June–July–August) precipitation over China are investigated using the reforecast (1983–2010) from the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). The CFSv2 for 1 month lead (LM0) predicts the leading pattern of Eurasian SWE in spring well, characterized by homogeneous variations over most of Eurasia centred on Siberia. Overall, the CFSv2 for LM0 exhibits a reasonable level of prediction skill for variations of Siberian spring SWE, but the initial SWE in the CFSv2 shows a dominant effect on the reforecasted Siberian SWE climatology. Using the initial condition in April, the CFSv2 can predict the SWE over Siberia in May and the corresponding summer rainfall pattern over China. Positive SWE in May in the CFSv2 is associated with negative summer rainfall anomalies in South and North China and part of Northeast China, and with positive anomalies between the Yangtze River and the Huaihe River and over Inner Mongolia and parts of the north of the Tibetan Plateau and southeastern Tibetan Plateau. The result is consistent with observed features.