Analysis Of Extreme Climate Characteristics In Linfen

Based on the data from Linfen Meteorology Bureau of daily precipitation of 17 meteorology stations from 1977 to 2010 in Linfen area, using R95P method to calculate the threshold of the Linfen extreme meteorological elements in different regions as the standard of extreme weather events of Linfen area. Using IDW and Qudric Surface Method on ArcGIS to analysis the distribution of the threshold in Linfen.Using the linear trend method-. Mann-kendall testing and wavelet analysis to research the trend and the period of the extreme high temperature, extreme low temperature and extreme precipitation.At last,calculate the intensity of the heat island in Linfen and research its trend. We found:1) the extreme precipitation threshold and latitude are positive related in all the areas in Linfen.The total average rainy days vary through seasons.There is no extreme precipitation in winter. The average rainy days are increasing in Spring. Most rain falls in Summer,and there is a reduction in autumn.2) Extreme precipitation days in eastern part of Linfen were on the up trend from 1977 to 2007. It came up to significant level in 2007. The increase of extreme precipitation suddenly changed from 1990 to 1992. The extreme precipitation in middle part increased sharply from 2004. The sudden change happened in 1985. Extreme precipitation continued to show an upward tendency in the western part,The sudden change happened from 1996 to 1999. And it came up to significant level from 2009 to 2010, and the sudden change happened in the late 1990s. The extreme rainy days in August had been increasing from the 1980s and changed in 1993.The extreme rainy days in September had been increasing from the 1980s and changed in 1993.3) The warm day-time days tended to increase in Linfen from 1977 to 2010. The days decreased from 1977 to 1979 and rising from 1979 to 1981.The sudden change happened in 1993. It camp up to obvious level in 2003.The warm day-time days varied in obvious periods and fluctuated in 5a time scale.the fluctuation is not that apparent from 1990 to 2000.The total warm day-time days were 32a.4) The cold night days were entering in a down trend from 1977 to 2010.However, the days were in a rising trend from 1977 to 1979.Since then, the total days had been decreasing,but not that disticnt.The sudden change happened from 1996 to 1997.The cold night days varied in obvious periods and fluctuated in 2-5a time scale and 10-15a time scale.5) Linfen 1977-2010 is more than or equal to 35 centigrade high temperature days showed a significant increase in 34a. Linfen 1977-2010 is greater than or equal to 35 degrees Celsius, the total number of days in 1994, mutation, and from the beginning of 2008, Linfen city of more than 35 degrees Celsius high temperature days were significantly increased. The interannual variation of the number of cycles of 35 degrees Celsius high temperature days in Linfen area is more than or equal to the total 3-5a and about 30a time scale periodic oscillation,30a is the first main period of not less than 35 degrees Celsius, the total number of days change; in addition,5a is the second main periods of cold night days.6) Linfen City daily minimum temperature is lower than the change in the 34a between the trend of total -15 degrees Celsius number is very weak, the trend rate of about 0.3d/lOa. Linfen City, the lowest temperature lower than -15 degrees Celsius,2-5a and 5-10a are the total number of time scaleperiodic oscillation, the first main period of interannual variability of 4a lower than -15 degrees Celsius of the total number of days for the lowest temperature,8a second main periods of cold nightdays. The upward trend of-20 degrees Celsius of the total number of days 34a daily minimum air temperature is lower than the city of Linfen. After the 1982 Linfen daily minimum temperature lower than -20 degrees Celsius the total number of days during the period increased gradually. The mutation occurred in the vicinity of 1993 and 1997, from the beginning of 2003, Linfen City, the lowest temperature is less than the total number of -20 degrees Celsius was significantly increased. Linfen City daily minimum temperature is lower than theinterannual variability of -20 degrees Celsius of the total number of days of periodic oscillation of 2-5a and lOA on time scales, the first main period of 5a is lower than that of the interannual variability of -20 degrees Celsius of the total number of days for the lowest temperature; 2a second main periods ofdaily minimum temperature lower than -20 degrees Celsius of the interannual variability of the total number of days,10 as the third main period.