Uncovering global climate fields causing local precipitation extremes

Abstract

ABSTRACTEarlier studies have focused on establishing the hydroclimatic teleconnection between hydrological extremes and a single or a few preselected coupled oceanic–atmospheric circulation patterns (OACP). In this study, we hypothesise that local (continental-scale) hydrological extremes are, in general, influenced by a concurrent effect of different climate variables from several regions across the globe. The suite of these variables is termed the global climate pattern (GCP) behind the target hydrological event. To explore our hypothesis, we considered monthly Indian rainfall, which is a complex, continental-scale hydrological phenomenon. Extreme events are identified through the standardized precipitation anomaly index (SPAI), used as an indicator of dry and wet events. The global fields of different climate variables—sea surface temperature (SST), surface pressure (SP), air temperature (AT), wind speed (WS) and total precipitable water (TPW)—are explored for possible revelatory patterns. In all, 15 different variables, each designated by a climate anomaly from a distinct zone on the globe, are found to form a potential global climate signal pool, which can be designated as the GCP for Indian rainfall. The combined information extracted from this GCP is proven to be highly efficient in predicting dry and wet events in Indian rainfall.EDITOR Z. W. Kundzewicz; ASSOCIATE EDITOR G. Di Baldassarre