摘要
高温热害已成为玉米生长过程中的一个重要威胁。本文中,我们定量分析了省份尺度上夏季极端高温日数对玉米产量的影响,结果表明在中国不同省份,当高温指数增加一个标准差时,玉米减产范围为-1.56%^-15.06%,其中以东北、华北地区减产最为严重。进一步分析表明,在1990年代中后期东北、华北极端高温日数显著增加,发生突变。当东北、华北上空500 h Pa位势高度场出现正异常时,天气比较晴朗,入射太阳辐射增加,使得地面温度升高,有利于极端高温天气的出现;而风场上,东北地区尤其是黑龙江盛行西风,经向环流减弱,冷空气不易入侵,使得该区温度偏高,华北地区则以偏南风为主,来自中国内陆的温暖气流被带到该地,为极端高温天气的发生创造有利条件。影响东北极端高温天气的关键海域位于黑潮地区,而ENSO对华北极端高温日数的影响更大,当ENSO指数异常偏高时,西太平洋副热带高压偏东,华北水汽输送通道受阻,水汽辐散,且盛行下沉运动,华北地区易出现高温、干旱天气。
Heat stress has posed a major threat to maize growth. In this paper, the authors analyze the impact of summer extreme high temperature on maize yield at provincial scales in China. Results show that in 18 provinces, the maize yield would decrease dramatically from -1.56% to -15.06% for each standard deviation increase in extreme high temperature days, especially in Northeast China and North China. Further analysis indicates that extreme high temperature days in both Northeast China and North China appeared to increase abruptly in the middle to late 1990s. For Northeast China and North China, when the geopotential height anomaly at 500 hPa is positive, the weather is clear, which is conductive to the increase in solar radiation and favorable for the occurrence of high temperature. Looking at wind fields in the lower levels, westerly winds often prevail in Northeast China especially in Heilongjiang Province. Strong zonal circulations can block the invasion of cold air mass from high latitudes. For North China, warm temperature advection by southerly winds is dominant, which is favorable for the formation of extreme high temperature. The key oceanic region that has significant impacts on extreme high temperature in Northeast China is the Kuroshio region, while the main oceanic region affecting North China is the equatorial eastern Pacific. Positive anomalies in this region would lead to eastward shift of the western Pacific subtropical high. With insufficient supply of water vapor and strong downdrafts, North China is prone to high temperature weather.
出处
《气候与环境研究》
CSCD
北大核心
2017年第2期134-148,共15页
Climatic and Environmental Research
基金
中国气象科学研究院基本科研业务费专项基金项目2016Y007~~
