咸阳北部塬区春末夏初干旱的气候特征及预测模型

Climatic characteristic and forecast model of drought in late spring and early summer in the upland of North Xianyang area

应用自然正交函数分解(EOF)方法,分析了陕西省咸阳市北部塬区春末夏初干旱的综合评价指数DH的空间分布特征及随时间演变规律及春末夏初干旱对冬小麦和玉米产量的影响;在此基础上,应用逐步回归方法建立了春末夏初干旱的预测模型。结果表明:咸阳市北部春未干旱发生几率具有同一性特征;在空间上分为南北两区,其中南区干旱几率大于北部;年际分布近年来具有频发连旱趋势,并在时空分布上具有同一性。根据干旱指数DH分布特征建立春未降水预报模式,业务使用效果良好。

The drought in late spring and early summer is analyzed by EOF combined with the DH in the upland of north Xianyang,Shaanxi Province.Its distribution feature and deve-lopment rule with time is analyzed and some suggestions are made.The influence on the yield of winter wheat and corn is pointed out.Then a drought forecast model is established with regression method.The results showed that the probability of occurrence of late spring drought in the area has identity characteristics.It is spatially distributed in two parts,north and south,of which the south is higher than the north,while for annual distribution,there appears a trend of increasingly frequent and continuous drought in recent years.And there is an identity for temporal and spatial distribution.The forecast model, established according to distribution characteristics of drought index DH of the two parts proves to be effective.