This study explores the characteristics of high temperature anomalies over eastern China and associated influencing factors using observations and model outputs.Results show that more long-duration(over 8 days) high temperature events occur over the middle and lower reaches of the Yangtze River Valley(YRV) than over the surrounding regions,and control most of the interannual variation of summer mean temperature in situ.The synergistic effect of summer precipitation over the South China Sea(SCS) region(18°–27°N,115°–124°E) and the northwestern India and Arabian Sea(IAS) region(18°–27°N,60°–80°E) contributes more significantly to the variation of summer YRV temperature,relative to the respective SCS or IAS precipitation anomaly.More precipitation(enhanced condensational heating) over the SCS region strengthens the western Pacific subtropical high(WPSH) and simultaneously weakens the westerly trough over the east coast of Asia,and accordingly results in associated high temperature anomalies over the YRV region through stimulating an East Asia–Pacific(EAP) pattern.More precipitation over the IAS region further adjusts the variations of the WPSH and westerly trough,and eventually reinforces high temperature anomalies over the YRV region.Furthermore,the condensational heating related to more IAS precipitation can adjust upper-tropospheric easterly anomalies over the YRV region by exciting a circumglobal teleconnection,inducing cold horizontal temperature advection and related anomalous descent,which is also conducive to the YRV high temperature anomalies.The reproduction of the above association in the model results indicates that the above results can be explained both statistically and dynamically.
In the context of global warming,apparent decdal-interdecdal variabilities can be detected in summer precipitation in southern China.Especially around the 1990 s,precipitation in South China experienced a phase transition from a deficiency regime to an abundance regime in the early 1990 s,while the Yangtze River Valley witnessed a phase shift of summer precipitation from abundance to deficiency in the late 1990 s.Pertinent analyses reveal a close relationship between such decadal precipitation shifts and moisture budgets,which is mainly modulated by the meridional component.This relationship can be attributed to large-scale moisture transport anomalies.Further,the HYSPLIT model is utilized to quantitatively evaluate relative moisture contributions from diverse sources during different regimes.It can be found that during the period with abundant precipitation in South China,the moisture contribution from the source of Indochina Peninsula-South China Sea increased significantly,while during the deficient precipitation regime in the Yangtze River Valley,moisture from local source,western Pacific and Indochina Peninsula-South China Sea contributed less to precipitation.It means some new features of relative moisture contributions from diverse sources to precipitation anomaly in southern China took shape after 1990 s.
