Interdecadal change in autumn rainfall over Southeast China and its association with tropical Pacific SST

Abstract In this paper, satellite datasets from the tropical rainfall measuring mission (TRMM), global precipitation climatology project (GPCP), and international satellite cloud climatology project (ISCCP) are used to reveal the interdecadal decrease in autumn rainfall in Southeast China (SEC) after 1990, along with Japan Meteorological Agency (JRA-55) reanalysis and observational rainfall datasets from the National Climate Center (NCC) of China, by means of the correlation coefficient and fast Fourier transformation (FFT) low-pass filter. The close and robust relationship between the interdecadal variation in autumn rainfall in SEC and sea surface temperature (SST) in the tropical Pacific is investigated. The most significant and stable region of correlation is located in 10°S–10°N, 160°E–160°W, in which there also exists interdecadal warming after 1990. Furthermore, the interdecadal warming of SST can induce Gill responses of the atmosphere: an cyclone anomaly is produced on each side of the equator in the lower troposphere, with a westerly anomaly to the west of the dateline. However, an anticyclone anomaly is produced in the upper troposphere. In particular, the cyclone anomaly on the northern side of the equator is located in the Northwest Pacific (WNP), and its ambient northerly airflow weakens meridional water vapor transport, in favor of the interdecadal decrease in SEC rainfall after 1990, as well as the local descending motion and low-troposphere divergence. In addition, the experiments also confirm that the interdecadal warming in the region (10°S–10°N, 160°E–160°W) would motivate the atmospheric Gill response and thereby cause the sinking motion in SEC and support the interdecadal decrease in autumn rainfall in SEC.