长江中下游水稻生长季极端高温和低温事件的演变趋势

Evolution Trend of Extreme High and Low Temperature Events during Rice Growing Period in the Middle and Lower Reaches of the Yangtze River

选取长江中下游稻区为研究区域,结合长江中下游6省实际水稻观测数据,从近30年的气候统计资料中提取发生在水稻生长关键期的极端高温和低温事件,并从极端事件发生的频次和强度两方面作了年代间的对比分析,探讨了水稻生长季极端气候事件的演变特征。结果表明,单季稻孕穗至灌浆期间的极端高温事件在长江以南地区发生频次比以北地区每年平均多2～3次;和20世纪90年代相比,2000年至今发生频次每年平均增多1～3次,强度增加0.5～1.3℃。早稻播种育秧期和晚稻抽穗至灌浆期的极端低温天气在长江以北地区的持续时间大于以南地区。与20世纪90年代相比,2000年至今,早稻播种育秧期间极端低温天气的持续时间在长江以南地区和以北地区分别减少1～3和4～7d,低温强度减少0.5～1.5℃;而晚稻抽穗至灌浆期极端低温天气在长江以北地区持续天数有小幅减少,但强度有所增加;而长江以南地区持续天数小幅增加,但强度有明显的减弱。

In this paper,the decadal change of frequency and intensity of extreme high temperature and low temperature events during the rice season in the middle and lower reaches of the Yangtze River were analyzed.The climate data and observed data on rice growing period in 1980-2007 were obtained from 65 agro-meteorological stations.The results showed that the frequency of extreme high temperature events in the south region of the study area was 2-3 times more than that in the north region for the single rice from booting stage to milking stage.Meanwhile,the frequency and intensity of extreme high temperature events in 2000-2007 increased 1-3 times and 0.5-1.3 ℃ respectively compared to that in the 1990s.The duration of extreme low temperature events was longer in the north region of the study area than that in the south region for early rice during the seedling-raising stage and for the late rice from heading stage to milking stage.Moreover,for the early rice during the seedling-raising stage,the duration of extreme low temperature events was shortened by 1～3 days in the south region and 4～7 days in the north region,while the intensity of the extreme low temperature events decreased by 0.5-1.5 ℃ for the whole study area.As for late rice,the duration of low temperature events from the rice heading stage to milking stage decreased slightly with the intensity increasing obviously in the north region of the study area,while the changes of both duration and intensity were opposite for the south region of the study area.