THE VARIATION OF THE SPRING PRECIPITATION IN GUANGZHOU AND ITS PRECURSORY SIGNALS

摘要

Guangzhou spring rainfall mainly exhibits interannual variation of Quasi-biannual andinterdecadal variation of 30 yrs, and is in the period of weak rainfall at interdecadal time scale.SST anomalies (SSTA) of Nino3 are the strongest precursor of Guangzhou spring rainfall. Theyhave significant positive correlation from previous November and persist stably to April. Nino3SSTA in the previous winter affects Guangzhou spring rainfall through North Pacific subtropicalhigh and low wind in spring. When Nino3 SSTA is positive in the previous winter, springsubtropical high is intense and westward, South China is located in the area of ascending airflow atthe edge of the subtropical high, and water vapor transporting to South China is intensified byanticyclone circulation to the east of the Philippines. So Guangzhou spring rainfall is heavy. WhenNino3 SSTA is negative, the subtropical high is weak and eastward, South China is far away fromthe subtropical high and is located in the area of descending airflow, and water vapor transportingto South China is weak because low-level cyclonic circulation controls areas to the east of thePhilippines and north wind prevails in South China. So Guangzhou spring rainfall is weak andspring drought is resulted.