小麦干热风灾害综合强度指数研究

A modified comprehensive intensity index of dry-hot wind hazard for wheat

干热风是我国北方麦区小麦生育后期经常出现的一种农业气象灾害,现有指标一般将干热风年型划分为无、轻、重3个等级,相同等级的年型之间难以进行相互比较;以往的研究通常只考虑高温低湿型,或将高温低湿和雨后青枯两种类型干热风分开分析,难以全面评价干热风的特点及其影响。本研究利用北方小麦主产区13省(区、市)178个站点1981—2015年小麦生育期内的逐日最高气温、14时相对湿度、14时风速、降水等资料,对干热风指数DHW进行了参数和类型修订,进而构建了涵盖高温低湿和雨后青枯两种干热风类型的干热风综合强度指数(CID);基于小麦因干热风造成的千粒重降低标准,提出了干热风当量日数(EDs)的概念,通过分析EDs与CID的关系,确定了北方小麦主产区各区域基于CID的干热风年型划分等级。干热风综合强度指数(CID)与干热风气象行业标准(QX/T82-2007)年型等级评价结果一致的比例,除新疆重区为84.4%外,其余各区域在90.9%至98.2%之间,表明CID具有较好的普遍适用性。基于CID对代表站点和典型干热风年的干热风时空特征分析表明:华北黄淮小麦主产区干热风强度呈减弱趋势,重区和次重区的变化趋势总体一致;而无论发生区域和发生强度,2001年均为1981—2015年中干热风最重的年份。干热风综合强度指数(CID)的建立实现了干热风强度的指数化综合评价,使具有相同年型等级的站点或年份之间干热风强度的时空对比分析成为可能,可作为现有干热风指标的拓展和补充,用于干热风灾害监测评估研究和服务。

Dry-hot wind is a common meteorological hazard for wheat in the northern China. The severity of the hazard is commonly classified as three classes： undamaged, slight damage, and severe damage. However, this classification can not benefit in depth comparsion analyses of the actual intensity of dry-hot wind over space and time for a specific class. Previous studies on dry-hot wind hazard were usually focused on the effect of high temperature with low humidity type, or high temperature with low humidity type but wilting heat after rain type separately. Thus, examination of the overall characteristics and impact was not feasible. In this study, using daily meteorological data （daily maximum temperature, relative humidity wind speed at 14：00, and daily precipitation） and wheat growth data from 178 stations in 13 provinces （regions, city） in the northern China from 1981 to 2015, we made parame- ter and type modification on DHW and developed a comprehensive intensity index of dry-hot wind （CID）. Both effects of high temperature with low humidity and wilting heat after rain were integrated into CID. Based on the decrease in 1000-grain weight caused by dry-hot wind, another metric, equivalent days （EDs）, was also established. We reclassified dry-hot wind damage based on CID for different wheat regions due to the linear-regression analysis between EDs and CID （P 〈0. 001 ）. Damage classes of dry-hot wind hazard determined by CID were in good agreement with those determined by the meteorological industry standard QX/T82-2007. Their ratios in the same hazard class varied from 90.9% to 98.2% , except for the severely affected region in Xinjiang with a value of 84.4%. The temporal and spatial patterns of CID showed that the dry-hot wind was the most severe in the year 2001 during 1981 to 2015 in terms of impacted areas and the intensity. The dry-hot wind intensity in both the severely and secondarily severely affected sub-regi＇ons decreased over the past 35 years in Huang-Huai-Hai region. It implied that the damage risk of dry-hot wind was reduced in this region. CID can be a complement to current indices in dry-hot wind damage assessment, as demonstrated in this study that it was useful for comparable quantitative analyses.