Relationship between Cooling of Tropical Pacific Sea Surface Temperature and Autumn Precipitation in China

Autumn precipitation in North China (APNC) is studied for 1951-2011 by using 160-station observed monthly precipitation in China, National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data, National Oceanic and Atmospheric Administration (NOAA) extended reconstructed sea surface temperature (SST), and the ECHAM5 general circulation model. In addition, the APNC and anomalous circulations recorded in September 2011 are compared with the statistical and numerical results. It is determined that the APNC shows dramatic interannual and interdecadal variability. The APNC was in a positive phase during the 1960s to early 1980s and in a negative phase in the 1950s, mid-late 1980s, and 1990s. Moreover, the strengthened APNC is closely related to westward stretching of the western Pacific subtropical high (WPSH). The cooling SST in the central tropical Pacific depresses the atmospheric convection over the region and exerts Rossby waves to enhance the convection over the western tropical Pacific. The local Hadley circulation is connected to convection over same region. The strengthened local Hadley circulation leads to anomalous anticyclones in the northwestern Pacific and is favorable for the westward movement of the WPSH via East Asia-Pacific (EAP) teleconnection, which increases the APNC. In 2011, negative SST anomalies in the central tropical Pacific and anomalous circulation contributed to extreme above-normal precipitation, which is consistent with the statistical and model experiment results.