Variations Of Temperature And Precipitation In Henan Province In Past49Years

The change of climate, especially the extreme weather often bring large disasters to human life and economy, so it is important to study their change trends and forecast its future changes. Based on the data of daily temperature and precipitation of17stations in Henan province1961to2009, the distribution characteristics of the climate reference values in Henan Province were analyzed, such as year, quarter and month average temperature and precipitation. The spatial distribution characteristics of the maximum, minimum temperature and maximum daily precipitation and the correlation between average temperature and precipitation from1961-2009were analyzed in this paper by using many analytical methods, such as linear trend, moving average, moving t test, Kriging method, wavelet analysis, Mann-Kendall and correlation analysis. The major conclusions were as follows:1. The annual precipitation and precipitation days decreased in the past49years. Except in1970s, the annual precipitation changed dramatically every10years from1961to2009. Precipitation and precipitation days in springs and autumns showeded declined trends, while that in summers and winters increased. The annual and seasonal variation of precipitation days had a decreased tendency during the past49-years. The precipitation days in spring and autumn showed an increase trend, while that in summer and winter decreased. The cycle analysis and mutation analysis of the meteorological elements showed that there was a2-4-year periodic oscillation in the change of annual precipitation and precipitation days. Seasonal precipitation and precipitation featured a2-4-year periodic oscillation in the span of49years and a6～8-year cyclic vibration in1970s-1990s. There were no abrupt changes on the time scale of precipitation except in the spring of1992. In1990s, the annual precipitation days experienced an abrupt change of abundant to short, while the spring and autumn precipitation days had an abrupt change of abundant to short in1997and1970respectively.2. The annual mean temperature, annual lowest temperature and highest temperature demonstrate a significant increase trend. The mean temperature and lowest temperature in spring and autumn increased, with a not significant downward trend of mean temperature, lowest temperature and highest temperature in summer. The seasonal and month temperature elements had the same variation trend as annual temperature elements. All of the climate elements showed an increasing trend, except the daily highest temperature in summer. The annual mean temperature showed a obvious increase tendency in the east and middle Henan. The spring mean temperature in south Henan changed more sharply than north Henan. In summer, the trends of mean temperature decreased from northeast to southwest of research area. All of the climate elements showed an increasing trend in autumn and winter and the increasing scale of the east was higher than the west. Annual temperature elements have a2-year to6-year periodic oscillation and season temperature elements have a4-year periodic oscillation. The annual mean temperature had a significant mutation in1997and showed an increasing trend. After1997, the highest (lowest) temperatures had the same mutation. In2001, the mean temperature of spring experienced a mutation of abundant to high. The mean temperature of winter experienced a mutation of abundant to high in1991.3. The spatial distribution of the meteorological elements:, the Henan extreme total precipitation was on increase, with a climatic tendency rate of1.2mm/lOa and the changes of extreme precipitation days were not significant. The frequencies of extreme precipitation events in middle Henan increased the most sharply, while the longest non-rainy days in middle Henan showed a more sharply increasing trend. Extreme high temperature events demonstrate a decrease to increase trend; in the west had a more upward trend than the other research area. The extreme low temperature events showed a decreasing trend, and the downward trend in west was larger then east.4. The results of correlation analysis showed that the annual mean precipitation and mean temperature moderately correlated. The correlation coefficient between mean precipitation and mean temperature in spring, summer and winter were over than0.3, which means those also moderately correlated. The monthly mean precipitation had a moderate correlation with mean temperature of January, May, June, July, August, September, October and November (P<0.01).