Interdecadal Variability of East Asian Summer Monsoon Precipitation over 220 Years （1777-1997）

In this study, long-term (1777–1997) precipitation data for Seoul, Korea, wetness indices from eastern China, and modern observations are used to identify the interdecadal variability in East Asian summer monsoon precipitation over the last 220 years. In the East Asian monsoon region, two long-term timescales of dry–wet transitions for the interdecadal variability and quasi-40-and quasi-60-year timescales are dominant in the 220-year precipitation data of Seoul, as well as in the wetness indices over China....

Interdecadal Variability of East Asian Summer Monsoon Precipitation over 220 Years (1777--1997)

In this study, long-term (1777--1997) precipitation data for Seoul, Korea,wetness indices from eastern China, and modern observations are used toidentify the interdecadal variability in East Asian summer monsoonprecipitation over the last 220 years. In the East Asian monsoon region, twolong-term timescales of dry--wet transitions for the interdecadalvariability and quasi-40- and quasi-60-year timescales are dominant in the220-year precipitation data of Seoul, as well as in the wetness indices overChina. The wet and dry spells between Seoul (southern China) and northernChina are out-of-phase (out-of-phase) at the quasi-60-year timescale, andin-phase (out-of-phase by approximately 90^o before 1900 and in-phaseafter 1900) at the quasi-40-year timescale. In particular, during the lastcentury, the dominant long-term timescales over East Asia tend to decreasefrom the quasi-60-year to the quasi-40-year with increasing time. Thedominant quasi-40-year and quasi-60-year timescales of the Seoulprecipitation in Korea are strongly correlated with these timescales of thenorthern Pacific Ocean.