Increased Predictability of Spring Precipitation over Central East China around the Late 1970s

The predictability of spring (March-May) precipitation over East China is investigated in the present study, based on the February-start hindcasts of eight state-of-art coupled models from DEMETER and ENSEMBLES during 1960-2001. Five out of the eight models exhibit significantly increased predictability of central East China spring precipitation (CECSP) after the late 1970s. The mechanism analysis indicates that CECSP variability is closely related with a meridional dipole atmospheric pattern at 200hPa over East Asia, whose prediction skill experienced an interdecadal increase around the late 1970s, therefore providing an enhanced prediction source for the CECSP after the late 1970s. Observational analysis indicates that the tropical sea surface temperature (SST) experienced notable decadal change around the late 1970s, after which it exerted a significant impact on East Asian atmospheric circulation. The five models could well reproduce the observed enhanced connection between the tropical SST and East Asian atmospheric circulation after the late 1970s, consequently showing higher predictability of East Asian atmospheric circulation and CECSP. However, the other three models cannot reproduce the relationship between the tropical SST and East Asian atmospheric circulation; therefore, CECSP predictability in these models remains low during the entire period. The increased predictability is valuable for current dynamical seasonal prediction for central East China.