Preliminary Analysis Of Fujian Province During The Rainy Season Precipitation Anomaly Regularity And Its Causes

This paper analyzes the anomaly regularity of rainfall in the raining season in Fujian and the cause responsible for the anomaly. The data used in this paper include the surface observational precipitation (observation period: 1961-2003) of Fujian province;Extended Reconstructed 2° × 2° grid monthly mean Sea Surface Temperature (period: 1961-2003) provided by American NOAA;global 2.5° × 2.5° grid monthly mean geopotential height and Sea Level Pressure provided by American NCEP/NCAR Reanalysis data. several statistical and synoptic methods are utilized in this study, such as Empirical Orthogonal Function (EOF) decomposition, Singular Value Decomposition (SVD), wavelet transform, Composite Analysis and Correlation Analysis.The climate characteristics of rainfall in the raining season in Fujian and related circulation pattern were analyzed in detail in this paper. More attention was paid on studying the relationship between Sea Surface Temperature anomalies (SSTA) over the north Pacific and raining season precipitation anomaly in Fujian. The results are as follows:1. The leading feature that flood happened everywhere in Fujian at the same time and so do drought had a 2-3-year cycle, a 5-7-year cycle and a 5-7-year cycle of precipitation variability in Fujian province in the recent 43 years. The most spatial difference was the difference between the southeastern and the northwestern, and it had a 6-7-year cycle and a 2-3-year cycle. These cycle characters represent difference in diverse period. In addition, there is a distinct inter-decadal trend in precipitation and the transition occurs in late 1970s, these days precipitation in the raining season shows a relative drought period. Precipitation exists reverse change between the Changjiang and Huaihe River basins area and Fujian area in the raining season. The certain relationship between more precipitation year and less precipitation year are found in the South of China and South of the Changjiang River area as well as in Fujian. During the past 43 years, when distinct more precipitation in early flood period occurs, subsequent late flood period never do so. Whereas distinct less precipitation in early flood period happens, the precipitation of subsequent late flood period appears similarly less three times.2. The severe flood and drought years are identified according to three ways. The study shows that the raining season rainfall anomaly in Fujian is closely related to Indian low, surface southwest reverse trough, west Pacific subtropical high, westerly troughs and ridges in the middle and higher latitude, south Asia high and cold air activity on the corresponding period. Some similar circulation pattern also appears in the preceding winter and early spring, has great difference between the corresponding and following period (summer).3. The correlation analysis shows precipitation in raining season of Fujian appears the significant positive correlation with the corresponding SST of the Kuroshio, west wind drift region;and has the negative correlation with the corresponding SST of the middle and lower latitude over eastern Pacific in north of equator, southernPacific, Atlantic in east of South America, the relativity strongly continues from last winter to summer. The study suggests that the previous period (last winter and early spring) SST anomalies in particular areas may play as a significant preceding signal for forecasting the drought and flood in the raining season in Fujian. The influence of key zones SST anomaly over north Pacific in early spring and raining season on precipitation anomaly in flood season in Fujian appears through the relationship between SST anomaly and atmospheric circulation anomaly, meanwhile circulation anomaly has certain impact on SST variability that come afterwards, the influence appears obviously in the middle and higher latitude of north Pacific.