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A model‐circulation increment‐based dynamic statistical technique (MIDST) is proposed in this paper to improve the prediction of summer rainfall over southern China (SC) where quite low prediction skills have been found in the Beijing Climate Center Climate System Model version 1.1 with a moderate resolution (BCC_CSM1.1m). The results show that BCC_CSM1.1m can hardly represent the variability of the summer rainfall anomaly and its year‐to‐year increment over SC, and the skillful predictions are mostly confined over the middle reaches of the Yangtze River. Using the dynamic model output and statistical method, the MIDST is established to capture the coupled modes between the year‐to‐year increments of the summer rainfall anomaly and the associated simultaneous three‐dimensional coupled air‐sea circulation predictors. The cross‐validation indicates that the prediction skills of the MIDST are evidently improved for both the summer rainfall increment prediction and summer rainfall anomaly prediction compared with the direct BCC_CSM1.1m prediction. The skillful prediction can persist for long forecast leads over most regions except southwestern China. As the major predictability source of seasonal prediction, the intense response to changes in the circulation related to the El Niño‐Southern Oscillation (ENSO) is well captured, and thus, the performance improvement of the MIDST is primarily due to its more realistic representation of the incremental circulation related to the ENSO. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, an objective identification technique for regional extreme events (OITREE) is used to identify regional drought events (RDEs) in southern China based on the daily precipitation dataset of 342 stations from 1961 to 2012. Generally RDEs in southern China occur over an entire year, with high frequencies from January to April and peak frequencies in February and March. The spatial distributions of frequency and intensity of RDEs are consistent, with high frequencies of more than 60 and the annual average number of drought days being more than 30 in most regions of southern China east of 105 ° E. The trend distributions of the frequency and intensity of RDEs in southern China are similar, with increasing trends in most western regions and decreasing trends in most eastern regions. The decreasing trends of RDEs in most eastern regions were mainly affected by the weakening of East Asia summer moonsoon (EASM) from the 1960s to the 1990s, which resulted in the summer main rain belts in eastern China moving from North China to southern China and caused the precipitation increasing in eastern regions of southern China from the 1960s to the 1990s. While the increasing trends of RDEs in most western regions were not only affected by the EASM, but also associated with the weakening of the India-Burma Trough (IBT) that caused less wet air transport to Southwest China and the decrease of precipitation in western regions of southern China. [ABSTRACT FROM AUTHOR]

ABSTRACT Between January and May 2011, southern China suffered perhaps the most severe drought since 1954. This investigation was carried out based on OLR ( Outgoing Long-wave Radiation) data derived from NOAA/ AVHRR satellite observations, precipitation records at 753 meteorological stations in China and NCEP reanalysis data during 1990 and 2011. This was done by first calculating the January to May climate averages of all required atmospheric parameters during 1990 and 2011, and then calculating the January to May 2011 anomalies (the difference between the parameter value in January to May 2011 and its climate average), with the goal to understand the dynamic and thermal mechanisms behind the 2011 5 month drought. Results show that during the drought: (1) the large-scale circulations were abnormal with a strengthened Mongolian High, a weakened subtropical high and abnormal northerly winds prevailing over southern China and the South China Sea; (2) the air was drier due to the anomalous deep dry-cold air column at middle and lower levels over southern China (linked to the northerly wind from the Mongolian anticyclone and the northwesterly wind from the Yellow Sea cyclone); (3) the abnormal air temperature structure, i.e. warm at higher levels (due to the abnormal South Asian High) and cold at middle and lower levels (due to the anomalous deep dry-cold air column over southern China), and (4) a formation of an abnormal mesoscale circulation structure, with the cyclonic convergence at the mid-level low (due to the Yellow Sea cyclone), the anticyclonic divergence at the low-level small high (due to the Mongolian anticyclone) and the resulting abnormal vertical downward movement over southern China. All these factors contributed significantly to the January to May 2011 drought over southern China. [ABSTRACT FROM AUTHOR]