1960—2019年海河平原地区夏玉米生长季高温特征分析

Spatio-temporal Characteristics of Extreme Heat During Summer Maize Growing Season in Haihe Plain from 1960 to 2019

夏玉米生长季高温频发给夏玉米生产带来极大的不确定性。为系统分析海河平原地区夏玉米生长季高温年际和年内分布规律,本研究基于研究区26个气象站点1960—2019年逐日最高气温数据,以35℃作为夏玉米高温阈值,从高温事件个数和持续天数、生长季高温日数和高温度日4个方面展开研究。研究结果表明,4个高温指标在空间上都呈现出由东北部沿海地区向西南内陆地区增高的趋势。1960—2019年间夏玉米生长季高温指标的年际变化存在1972、1996年2个明显的突变点,将这60年分割成高温较强—较弱—较强3个时期;6月中旬—7月上旬发生高温的日数最多,占6—9月高温日数总和的69.8%,而6月下旬—7月下旬各旬的高温日数年际变化与生长季高温年际变化规律最为接近,是影响生长季高温变化的主要时段。研究结果对于全面掌握研究区夏玉米生长季高温时空分布特征、指导夏玉米生产具有一定的意义。

Under global climate change,frequent extreme heat during summer maize growing season has brought great uncertainty to summer maize yield and attracted wide attention.The interannual and seasonal distribution characteristics of extreme heat during summer maize growing season in Haihe plain was systematically analyzed.The daily maximum temperature data at 26 meteorological stations in the study area from 1960 to 2019 were used to detect extreme heat events,and 35°C was taken as the extreme heat threshold of summer maize.Extreme heat characteristics,including the number and duration of extreme heat events,the number of extreme heat days and the extreme heat degree days during summer maize growing season were analyzed in this study.The results showed that the four extreme heat characteristics all showed an increasing trend from the northeast coastal area to the southwest inland area.The interannual variations of extreme heat characteristics during summer maize growing season from 1960 to 2019 had two obvious change points in 1972 and 1996,and these two change points divided the study years into three periods:strong,weak and strong.From mid June to early July,the number of extreme heat days was the biggest,accounting for 69.8%of the total extreme heat days during June to September.The interannual variation of extreme heat days from late June to late July were most similar with the interannual variation of extreme heat,and could be regarded as the main period affecting the variation of extreme heat during summer maize growing season.The results have certain significance for comprehensively grasping the spatial and temporal distribution characteristics of extreme heat in the study area and guiding the production of summer maize.