衢州市早稻低温冷害风险评估及大气环流背景分析

应用衢州市1960—2012年日气象观测资料,针对早稻苗期出现低温冷害灾害,从气象因子入手,建立定量评估模型,分析较严重的早稻春季低温冷害年大气环流背景,为提高春季低温冷害预报和预警水平,应对春季低温冷害对早稻构成的严重威胁。采用主分量分析法确定主分量及表达式,建立综合评价指标模型,计算出综合评价指标,并且对历年综合指标进行了评价。应用NCEP 1°×1°500 h Pa、850 h Pa资料,分析了较严重春季低温冷害年的大气环流背景。结果表明:从1960—1997年春季低温冷害发生频率3~4年出现一次,强度为1987—1997年最强,2000年以后,春季低温发生次数甚少。1987年、1993年、1996年、2010年出现了较严重的早稻春季低温冷害,相对应的气候异常。综合评价指标和早稻产量相关密切,能客观地反映低温冷害的风险程度。较严重的早稻春季低温冷害年4月上中旬亚欧地区呈径向型环流,使冷空气活动频繁南下,导致长江中下游地区气温偏低,而副热带高压强度强,南支槽、西南暖湿气流活跃,造成长江中下游地区持续阴雨天气。西风带、副热带、热带系统的有利配置,是造成早稻春季低温冷害发生的大气环流背景。

Risk Assessment of Chilling Damage to Early Rice and Analysis of Atmospheric Circulation Background in Quzhou

The paper aims to study the damage caused by early spring chilling injury in rice seedling emergence period with the daily meteorological observation data of 1960-2012 in Quzhou. The authors started from the meteorological factors, established a quantitative evaluation model, analyzed the severe chilling injury in early spring atmospheric circulation background, in order to improve the early spring chilling damage forecast and warning level, and to deal with the serious threat of chilling damage in spring to early rice, which was of significance to ensure grain production safety. With the application of NCEP 1°×1°, 500 hPa and 850 hPa data, the authors analyzed the atmospheric circulation background of the severe cold springs from the height field and temperature field distribution. The result showed that the frequency of chilling damage in spring was once 3 to 4 years from 1960 to 1997, the strongest strength period was in 1987 to 1997. After 2000, there were fewer low temperature occurrences in spring. Throughout the years of comprehensive evaluation index, there were serious spring rice chilling damages in Quzhou in 1987, 1993, 1996 and 2010, corresponding to the abnormal climate at the same time. The comprehensive evaluation index was closely related to early rice yield, it could objectively reflect the degree of risk of chilling injury. In years with serious early spring chilling damage, the Asia Pacific region showed radial circulation in early and middle of April, which drove the cold air to go southward frequently, resulted in low temperature in the downstream area of the Long River. The subtropical high was strong, the south branch trough and southwest warm wet air occurred actively, caused the weather to be rainy and overcast in the Long River region. The favorable configurations of westerlies, subtropical and tropical system were the atmospheric circulation background of early spring low temperature injury.