Feature analysis and primary causes of pre-flood season “cumulative effect” of torrential rain over South China
- 191 Downloads
When persistent rainfall occurs frequently over South China, meso-scale and micro-scale synoptic systems persist and expand in space and time and eventually form meso-scale and long-scale weather processes. The accumulation of multiple torrential rain processes is defined as a “cumulative effect” of torrential rain (CETR) event. In this paper, daily reanalysis datasets collected by the National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) during 1979–2014 are used to study the anomalous features and causes of heavy CETR events over South China. The results show that there is a significant difference in the spatial distribution of the heavy CETR events. Based on the center position of the CETR, the middle region displayed middle-region-heavy CETR events while the western region displayed west-region-heavy CETR events. El Niño events in the previous period (December, January, February, March (DJFM)) are major extra-forcing factors of middle-region-heavy CETR events, which is beneficial for the continuous, anomalous Philippine Sea anticyclone and strengthens the West Pacific Subtropical High (WPSH), extending it more westward than normal. The primary water vapor source for precipitation in middle-region-heavy CETR events is the Tropical Western Pacific Ocean. The major extra-forcing factor of a west-region-heavy CETR is the negative anomaly in the southern Tropical Indian Ocean (TIO) during the previous period (DJFM). This factor is beneficial for strengthening the cross-equatorial flow and westerly winds from the Bay of Bengal to the South China Sea (SCS) and early SCS summer monsoon onset. The primary water vapor source of precipitation in the west-region-heavy CETR is the southern TIO.
This research was jointly supported by The National Natural Science Foundation of China (Grant Nos. 41375078, 41530531, 41305059, 41305100) and the National Science and Technology Support program under Grant No. 2015BAC03B06.
- Bao M (2007) The statistical analysis of the persistent heavy rain in the last 50 years over China and their backgrounds on the large scale circulation. Chin J Atmos Sci 31(5):779 (in Chinese)Google Scholar
- Bao M, Huang RH (2006) Characteristics of the interdecadal variations of heavy rain over China in the last 40 years. Chin J Atmos Sci 30:1057 (in Chinese)Google Scholar
- Feng GL, Yang HW, Zhang SX (2012a) A preliminary research on the reason of a sharp turn from drought to flood in the middle and lower reaches of the Yangtze River in late spring and early summer of 2011. Chin J Atmos Sci 36(5):1009 (in Chinese)Google Scholar
- Gao ST, Zhao SX, Zhou XP, Sun SQ, Tao SY (2003) Progress of research on sub-synoptic scale and mesoscale torrential rain systems. Chin J Atmos Sci 27:618 (in Chinese)Google Scholar
- Huang J, Wang S (1992) The experiment of seasonal prediction using the analogy-dynamical mode. Sci China B 35(2):207Google Scholar
- Huang J, Yi Y, Wang S, Chou J (1993) An analogue-dynamical long-range numerical weather prediction system incorporating historical evolution, Q. J. Roy Meteor Soc. 119 (511), 547.Google Scholar
- Wu R, Chen W, Wang G (2014) Relative Contribution of ENSO and East Asian winter monsoon to the South China Sea SST anomalies during ENSO decaying years. J Geophys Res 119(9):5046Google Scholar
- Zhang SX, Feng GL, Zhao JH (2013) “Cumulative effect” of torrential rain in the middle and lower reaches of the Yangtze River. Acta Phys Sin 62:496 (in Chinese)Google Scholar
- Zheng Z, Ren H, Huang J (2009) Analogue correction of errors based on seasonal climatic predictable components and numerical experiments. Acta Phys Sin 58(10):7359 (in Chinese)Google Scholar
- Zhi R, Lian Y, Feng GL (2007) The influence of different scale systems on precipitation analyzed on the basis of power-law exponent. Acta Phys Sin 56:1837 (in Chinese)Google Scholar
- Zhou LT, Wu R (2010) Respective impacts of the East Asian winter monsoon and ENSO on winter rainfall in China. J Geophys Res 115, D02107Google Scholar