Interdecadal change in the interannual relationship between spring tropical Indian ocean sea surface temperature and summer extreme precipitation in northern Xinjiang of Northwest China

Based on the daily precipitation data released by the China Meteorological Data Service Centre, the monthly Sea Surface Temperature (SST) provided by the National Oceanic and Atmospheric Administration (NOAA) and monthly atmospheric reanalysis data extracted from the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) during 1961–2022, we examine the interdecadal change in the relationship between spring Indian Ocean SST (IOSST) and summer extreme precipitation (SEP) in northern Xinjiang of Northwest China. Results show that the IOSST-SEP relationship has experienced an obvious interdecadal change, especially between 1963 and 1983 and 1984–2004, and in the latter period their relationship significantly becomes closer. The meridional movement of the subtropical westerly jet (SWJ) over Central Asia (CA) can well affect the Central Asian cyclone and transport of water vapor and is responsible for the SEP in northern Xinjiang, which plays an important role in linking IOSST and SEP. During 1963–1983, the persistence of anomalous IOSST signals from spring to summer strongly depends on El Niño, so the IOSST is manifested as a heat sink and cannot influence the meridional movement of the SWJ over CA. However, during 1984–2004, the persistence of anomalous IOSST signals from spring to summer is independent of El Niño, and the IOSST is manifested as a heat source and can modulate the meridional movement of the SWJ over CA via Gill-type atmospheric response.