滕州市近50年气候干湿变化

利用滕州市1956~2005年降水量、平均气温资料,用Holdridge干燥度指数来分析近50年气候干湿变化趋势和特征。滕州市近50年来在年生物温度、年可能蒸散量极显著上升背景下,年降水量不显著的减小趋势,造成年水分盈亏量显著亏损及年干燥度指数显著增大,总体呈现暖干化趋势。年干燥度指数变化有明显的阶段性,干湿期交替变化,大体经历了3个湿期和2个干期。1976年年干燥度指数发生由偏湿向偏干的突变,突变后气候类型分布发生显著变化。通过对近50年年干燥度指数滑动平均值和标准差分析发现:随着干燥度指数平均值的增大,异常湿事件明显减少,而异常干事件明显增多,同时,随着标准差的增大,异常干湿事件频率明显增大。

Climate Change of Drought/Wetness in Tengzhou in Last 50 Years

The calculation is made of the Holdridge aridity index to analyze climate tendency and characteristics of drought/wetness changes for the last 50 years by means of the mean air temperature and precipitation at Tengzhou from 1956 to 2005.The results show that under the influence of the obvious increase trend of annual bio-temperature and annual potential evapotranspiration,the indistinctive decrease trend of annual precipitation caused the obvious loss trend of annual water budget and the outstanding increase trend of annual aridity index. The aridity index varies periodically,and drought and wetness stages appear alternately.Generally there are three wetness stages and two drought stages.In 1976,the aridity abruptly turned from wet to dry.Climate types changed markedly after the abrupt climate transformation.Through the moving-average analysis of the aridity index and the standard deviation,it is found that along with the increase of average aridity index,unusual wetness events obviously decreased,but unusual drought events obviously increased.Along with the increase of the standard deviation,the total frequency of unusual drought/wetness events increased obviously.