The results of an analysis of the temporal and spatial distribution of typhoon precipitation influencing Fujian from 1960 to 2005 show that typhoon precipitation in Fujian province occurs from May to November, with the most in August. There has been a decreasing trend since 1960. Typhoon precipitation gradually decreases from the coastal region to the northwestern mainland of Fujian and the maximum typhoon precipitation occurs in the northeast and the south of Fujian. Typhoon torrential rain is one of the extreme rainfall events in Fujian. High frequencies of typhoon torrential rain occur in the coastal and southwest regions of the province. With the impact of Fujian's terrain, typhoon precipitation occurs more easily to the east of the mountains than to the west. Atmospheric circulation at 500 hPa over Asia and sea surface temperature anomalies of the equatorial eastern Pacific are analyzed, with the finding that they are closely connected with the anomaly of typhoon precipitation influencing Fujian, possibly mainly by modulating the northbound track of typhoons via changing the atmosphere circulation to lead to the anomaly of typhoon precipitation over the
Using the Joint Typhoon Warning Center(JTWC)and China Meteorological Administration(CMA) tropical cyclone track datasets,variations in frequency and intensity of the affecting-China tropical cyclones (ACTCs)are studied for the period of 1965-2004.First,the differences between the two tropical cyclone datasets are examined.The annual frequencies of tropical cyclones in the western North Pacific basin are reasonably consistent to each other,while the intensity records are less reliable.The annual numbers of ACTCs based on different datasets are close to each other with similar interdecadal and interannual variations.However,the maximum intensity and the annual frequency of ACTCs for strong categories show great dependence on datasets.Tropical cyclone impacts on China show the same variations as the annual number of ACTCs and also show dependence on datasets.Differences in tropical cyclone impacts on China are mainly caused by datasets used.The annual frequency of ACTCs,especially the length of lifetime of ones that make landfall,and the intensity estimates all have effects on the value of impacts on China.
The spatio-temporal characteristics of typhoon precipitation over China are analyzed in this study. The results show that typhoon precipitation covers most of central-eastern China. Typhoon precipitation gradually decreases from the southeastern coastal regions to the northwestern mainland. The maximum annual typhoon precipitation exceeds 700 mm in central-eastern Taiwan and part of Hainan, while the minimum annual typhoon precipitation occurs in parts of Inner Mongolia, Shanxi, Shaanxi and Sichuan, with values less than 10 mm. Generally, typhoons produce precipitation over China during April - December with a peak in August. The annual typhoon precipitation time series for observation stations are examined for long-term trends. The results show that decreasing trends exist in most of the stations from 1957 to 2004 and are statistically significant in parts of Taiwan, Hainan, coastal Southeast China and southern Northeast China. The anomaly of typhoon precipitation mainly results from that of the general circulation over Asia and the Walker Cell circulation over the equatorial central and eastern Pacific. Typhoon torrential rain is one of the extreme rainfall events in the southeastern coastal regions and parts of central mainland. In these regions, torrential rains are mostly caused by typhoons.
The data of landfalling tropical cyclones (TCs) in China and ENSO events and the NinoZ index during 1951 to 2005 were used to study the relationships between ENSO and landfalling TCs in China. ENSO events from July to September have obvious effects on landfalling TCs in China. When El Nio persists throughout the months, the frequency of landfalling TCs is less than normal, the season of landfalling TCs is shorter, the annually first landfall is later, the annually last landfall is earlier, and the mean intensity is stronger and more landfalling TCs achieve the intensity of typhoon. Otherwise is true for La Nia. That is to say, ENSO events evolving from July to September show strong prediction signals for landfalling TCs in China. When ENSO ends or starts in a year while the NinoZ index remains neutral in July through September, landfalling TCs also have some impacts of ENSO. El Nio events have more significant effects on landfalling TCs than La Nia events.
