Impact of Northward-Propagating Intraseasonal Variability on the Onset of Indian Summer Monsoon

摘要: The onset of the Indian summer monsoon (ISM) has a pronounced interannual variability, part which originates from large-scale circulation and its thermodynamic properties. While northward-propagating intraseasonal variabilities (ISVs) are prominent characteristic ISM, they tend to initiate an early by transferring moisture momentum deep tropics subcontinent. However, not all onsets ISM attributable strong ISVs can lead onsets. With daily index simpleregressionmodel, ofISMfrom1982 to2011 areseparated into two groups. years in closely related categorized as ISVO years, other non-ISVO years. former category is focus this study. Before ISMintheISVOyears,theconvectivefeaturesareprominent,suchasacycloneovertheBayofBengal(BoB) associated convection. ocean‐atmosphere interaction found be important for before Evidence shows that warm SST anomalies drive atmosphere atmospheric instability This reinforces more recent view ocean does just play passive role ISVs. process understandinghelpsshapethepathtoenhancingpredictiveunderstandingandmonsoonpredictionskillswith obvious implications prediction El Ni~ Oscillation.