Abstract:Using the daily precipitation data of 68 stations in Hubei and NCEP/NCAR circulation reanalysis data, the low-frequency characteristics of spring rainfall and its relationship with SST are studied. The results indicate that the quasi-biweekly oscillation of precipitation is obviously in spring over Hubei. Biweekly activity strengthens in the spring flood years while weakens in the spring drought years. The sea surface temperature anomalies (SSTA) of the Indian Ocean and Kuroshio in spring can cause circulation anomaly over the mid-low latitudes and Japan Sea, and then affect the low-frequency activity of spring precipitation in Hubei Province. Under the background of anomaly warmer SSTA of Kuroshio in the 2018 spring, there existed a positive anomaly of 500 hPa height field over the Japan Sea. This anomaly had significant low-frequency oscillation. The southeast flow in the rear part of this anomaly constituted the warm shear with the southwest flow from South China, causing low-frequency rainfall over Hubei. All these resulted in biweekly active abnormality.