Studying Western North Pacific High Activity in Relation to the East Asian Summer Monsoon Using GK-2A Data

Abstract

The Western North Pacific High demonstrates a close association with the East Asian Summer Monsoon. By employing GK-2A satellite data, we categorized the Western North Pacific High into three types and analyzed how the distinctive features of each type correlated with East Asian Summer Monsoon. The analysis extended from June to August, encompassing the years 2020 through 2023. Additionally, we utilized ERA5, NCEP2, and ASOS data for the same period to compare and complement the findings derived from the satellite observations. By performing empirical orthogonal function (EOF) analysis on the cloud amount data obtained from GK-2A observations over East Asia, we identified three primary modes: the first, second, and third modes denoting unimodal patterns, tropical influences, and high-latitude influences, respectively. Notably, the second mode is correlated with the northward movement of the East Asian rain bands attributed to the westward expansion and intensification of the western subtropical high. Moreover, there is a discernible lag relationship, PC1 precedes PC2 and PC2 precedes PC3. Consistency between the results obtained from ERA5 and NCEP2 data is evident across all modes, except for EOF1. These findings collectively underscore the potential of this study to detect variations in the Western North Pacific High and their impact on the East Asian Summer Monsoon. Acknowledgement: This research was supported by “The Technical Development on Weather Forecast Support and Convergence Service using Meteorological Satellites” of the NMSC/KMA (KMA2020-00121) and the National Research Foundation of Korea (NRF) grant funded by the Government of Korea (MSIT) (No. 2022R1A2C 1008858)