甘肃黄土高原春旱的气候特征及预测方法

利用甘肃黄土高原55个气象站在1968-2000年间的春季降水、气温资料, 计算了春季干湿指数, 划分了春旱标准, 用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, 计算了其与欧亚500hPa高度场、赤道北太平洋海温和高原加热场的相关关系, 建立了甘肃黄土高原春旱的均生函数预测模型。结果表明, 干旱有三个高发区, 频率为36%~57%, 约2~3年一遇, 且有增加的趋势。春旱与当年高原500hPa高度场、赤道北太平洋海温及上年盛夏高原加热场呈正相关, 与前期冬季高原加热场呈负相关, 所建立的预报模型有一定的预报能力。

Climatic Characteristics and Forecasting Method of Spring Drought in Loess Plateau of Gansu Province

The precipitation and temperature data at 55 observational stations from 1968 to 2000 have been used to calculate the spring drought index and set up the criterion of spring drought. Further, we have divided the climate regions on Loess Plateau with REOF method, have analyzed the spatial and temporal features of spring drought, have established the correlation of spring drought with 500 hPa height field over Asia and Europe, sea temperature of North Pacific near equator, and heating field on Qinghai-xizang Plateau. Finally, the forecasting model of Mean Generation Function is formulated for spring drought of Loess Plateau in Gansu Province. There are three high-frequently drought-occurred regions, the frequency are between 36%～57%, about once per 2 to 3 years, but it tends to increase. The spring drought has positive correlation with the 500 hPa height field, the sea temperature of North Pacific near equator in the same year and the heating field in last summer; while has negative correlation with Plateau heating field in prophase winter. The forecasting model has some ability to predict the spring drought.