甘肃东部春播期干旱指数的变化特征及预测

利用甘肃东部1968～2002年55站的春播期降水、气温资料，计算了春播期干旱指数，划分了春播期干旱标准，用自然正交分解(EOR)和旋转自然正交分解(REOF)方法进行了气候分区，分析了其时空分布特征和变化规律，经拟合与试报证明有一定的预报能力。结果表明，干旱有三个高发区，频率为36％～57％，20世纪90年代是干旱最严重的时段，进入新的世纪，干旱有减轻的趋势。最后建立了甘肃东部春播期干旱指数的均生函数预测模型。

The Characteristics and Prediction of Spring Drought Index in the East Gansu Province

Based on the precipitation and temperature data of 55 stations from 1968 to 2002, the spring drought indexes were calculated. The criteria of spring drought were established. By using Empirical Orthogonal Function (EOF) and Rotated Empirical Orthogonal Function (REOF) methods, the climate regions were divided and the spatial and temporal distribution of the spring drought indexes were analyzed. The results showed that three regions belonged to the drought frequent occurred areas with the drought frequency from 36% to 57% . The most serious periods of drought occurred in the 1990' s. The trend of drought occurrence was declined in the 2000' s. The forecast model of Mean Generation Function (MGF) based on spring drought indexes was able to predict the drought occurrence for the East Gansu Province.