**2. Meteorological Data**

This study adopted the following datasets:

(1) Records of daily precipitation data collected from 328 weather stations since the establishment of each station. The China Meteorological Data Service Centre qualified the raw data once for the period 1951–2010, free from data errors and missing data, ensuring the data quality of historical precipitation for the present study. We converted the ground station data into contours based on the kriging method;

(2) The 2◦ × 2◦ grid size that recorded average monthly SSTs worldwide between 1930 and 2000 from NOAA Extended Reconstructed SST V5 dataset [26];

(3) The 2.5◦ × 2.5◦ grid size that recorded horizontal wind fields and geopotential height fields in 1954 (retrieved from the NCEP/NCAR Reanalysis dataset on the National Ocean and Atmospheric Administration website) [27].

#### **3. Characteristics of the 1954 Precipitation Anomalies**
