基于CAST客观分类的华北平原干热风区划研究

 干热风是影响华北平原冬小麦生长发育及产量形成的重大农业气象灾害之一,本文利用华北平原48个站点1961—2008年逐日气象资料,分析了近50年来各站点的干热风(高温低湿型/雨后青枯型)日数。在此基础上,运用近年来提出的一种新型分区区划方法,即统计检验聚类方法(CAST),对高温低湿型和雨后青枯型2种类型的干热风日数构成的要素场分别进行了分区。结果表明：从地理空间而言,高温低湿型和雨后青枯型干热风日数总体上都呈现中部高南北低的趋势；从时间发生特征而言,除南部个别区域有增加趋势外,高温低湿型干热风日数呈明显的递减趋势,雨后青枯型干热风日数虽然总体也呈下降趋势,但局部呈上升趋势的站点数量多于高温低湿型。CAST分区结果表明,高温低湿型干热风可分为5个区,雨后青枯型干热风可分为4个区。这些分区均合理地反映了以荷载中心为代表的干热风日数随时间和空间的变化,比传统按等值线分区的方法更具优势。干热风的时空分布特征和利用CAST进行的分区为进一步建立干热风监测预警模式奠定了一定的理论和应用基础,并可为当地农业生产决策提供一定的实际指导。

Regionalization Study on Dry-hot Windy Days in the North China Plain Using CAST Model

Dry-hot wind day is one of the main argometeorological disasters which impact the development and yield of winter wheat in the North China Plain (NCP). Using daily meteorological data of 48 weather stations from the year of 1961 to 2008 in the NCP, the dry-hot windy days, that include two types, type one is high temperature and low humidity and type two is immature death after rain, are analyzed. Then by using dry-hot windy days and Cluster Analysis of Statistic Test (CAST), which is a newly developed regionalization method, the dry-hot windy days regionalization is carried out in the NCP. Results show that spatially speaking, both types of dry-hot windy days all present higher in the middle and lower in the south and north; temporally speaking, type one is slightly decrease in the last nearly fifty years, except the individual stations in the south part of the plain. Although type two of dry-hot windy days is also generally decrease in the past, however, the exceptional stations are higher than type one. Results of CAST indicate that for the type one, five regions are divided and for the type two, four regions are divided. Those regionalization results are reasonably reflecting the spatial and temporal changes of dry-hot windy days in those load centers, and CAST is more powerful than conventional regionalization methods. The results could provide the scientific and practical base for developing the monitor and forecast system of dry-hot wind days, and is also able to provide realistic instructions for the decision making on the agricultural managements of the local farmers.