Poster

IAMAS

M18 - Monsoon systems: variability, processes, predictability, change and extremes

Long-term change of quasi-stationary fronts and its precipitation in East Asia during summer

Precipitation in the Korean Peninsula is largely controlled by the East Asian monsoon and is characterized by a distinct rainy season in the summer which is known as Changma in Korea. Changma usually lasts for approximately a month from late June to late July, a period that is one of the major typical rainy seasons in East Asia, along with Mei-Yu (China) and Baiu (Japan). The East Asian region including Korea is affected by a quasi-stationary front formed by the collision of warm, humid air from the south and cold air from the north during the rainy season. The influx of humid air from strong southwesterly winds increases where the front is located, resulting in continuous rainfall. Understanding the changes in these fronts is crucial given the significant impact they have on regional weather. In this study, ERA-5 reanalysis data were used to objectively identify atmospheric fronts and confirm the climate distribution for East Asia. During the Changma, the porpotion of stationary fronts on the Korean Peninsula decreased significantly from approximately 31% in the past(1979-2001) to 24% in recent(2002-2023). The frequency of stationary fronts showed a decreasing trend in June and July, whereas it exhibited an increasing trend in August and September. Notable changes were observed in July and September. Furthermore, we examined characteristics in the meteorological field related to the quasi-stationary fronts to analyze the formation of the fronts.