Classification of typical summer rainfall patterns in the East China monsoon region and their association with the East Asian summer monsoon

In this study, the summer rainfall patterns in the East China monsoon region during 1951-2015 were objectively classified into four typical categories: the northern China rainfall pattern (NCP), the intermediate rainfall pattern (IRP), the Yangtze River rainfall pattern (YRP), and the South China rainfall pattern (SCP). The periods of the four patterns show significant decadal characteristics. The NCP occurred mainly between the late 1950s and the early 1980s, and the IRP in the late 1950s to the early 1970s and the 2000s. The YRP occurred mainly between the 1980s and the 1990s, and the SCP between the mid-1990s and the early 21st century. The relationship between the East Asian summer monsoon index (EASM I-WF) and the four rainfall patterns was comparatively analyzed. The results confirmed that the four rainfall patterns have obvious differences in the EASM. In the NCP, IRP, or SCP years, the EASM I-WF primarily showed a positive phase and a strong summer monsoon; in the YRP years, the EASM I-WF primarily showed a negative phase and a weak summer monsoon.