1961-2015年黄淮海地区冬小麦干热风灾害时空分布特征

干热风是影响北方小麦后期生长和产量形成的重大气象灾害之一，在黄淮海地区主要有高温低湿型和雨后青枯型两种类型。利用黄淮海冬麦主产区65个站点1961-2015年的逐日气象数据和冬小麦生育期资料，综合分析了过去55 a该地区干热风日数和干热风过程的总体时空分布与变化特征。结果表明：（1）年平均干热风日数、过程次数高值区位于河北中南部、河南北部、山东北部和西部等地，其中河北中南部为黄淮海地区的干热风重发区。（2）干热风多年平均初日和最早初日的空间分布均呈从南向北、从内陆到沿海逐渐推后的特征；随着小麦灌浆成熟进程，干热风发生日数呈逐渐增多趋势，灌浆中后期干热风日数多、程度重，是干热风危害的集中期和防御关键期。（3）黄淮海地区干热风日数、过程次数总体均呈减少趋势，其中重干热风日数、重过程次数减少趋势更为明显；从地区差异来看，冀东南、鲁西北、豫东北等地减少趋势更为明显。但在气候变暖背景下，极端天气气候事件频发，部分年份仍存在发生较重干热风的可能，如2001年区域平均干热风日数达8.1 d，成为1961-2015年干热风日数最多的年份，因此对干热风的防御仍需引起足够的重视。

Spatial-temporal characteristics of dry-hot wind for winter wheat in Huang-Huai-Hai region from 1961 to 2015

Dry-hot wind is one of the major meteorological hazards in Huang-Huai-Hai region, which commonly occurs at the filling stage of winter wheat and can severely influence the wheat growth and yield. There are two types of dry-hot wind in Huang-Huai-Hai region:1) high temperature with low humidity and 2) wilting heat after rain. By using daily meteorological data (daily maximum temperature, relative humidity at 14:00, wind speed at 14:00, and daily precipitation) and winter wheat growth data of 65 stations in Huang-Huai-Hai region from 1961 to 2015, the spatial-temporal characteristics of dry-hot wind in the past 55 years was analyzed. The results showed that both the dry-hot wind days and process times were higher in central-south Hebei province, north Henan province, and west and north Shandong province in Huang-Huai-Hai region; among these areas, central-south Hebei province was the most severely affected area. It was found that both the average first occurrence day and the earliest first occurrence day of dry-hot wind was gradually delayed from south to north and from inland to coast. Dry-hot wind days increased gradually with the grain filling process of winter wheat; thus, the mid and late phases of grain filling were identified as the critical resistance stages to dry-hot wind. Both the annual average days and process times of dry-hot wind showed decreasing trend from 1961 to 2015 in Huang-Huai-Hai region, especially the severe dry-hot wind days and severe process times decreased more obviously. Among of which, the decreasing trend was more obviously in southeast Hebei province, northwest Shandong province and northeast Henan province. It should be noted that extreme climate events occur frequently under the background of climate warming, and extreme dry-hot wind events may occur in some regions under certain conditions. For example, the average number of dry-hot wind days in Huang-Huai-Hai region was 8.1d in 2001, which was the maximum record from 1961 to 2015 in this region. It should be taken into account for the prevention of dry-hot wind in wheat planting.