1971—2011年河南省冬小麦晚霜冻的特征分析

Analysis of the characteristics of the late frost on winter wheat in Henan Province in 1971—2011

利用常规气象观测资料、河南省农业气象实验站资料、中国气象局历年搜集的霜冻灾情报告,对1971—2011年河南省冬麦区111个基本气象观测站霜冻低温进行EOF(正交函数分解)时空特征分析.结果表明,豫北、豫西、豫东一带是河南晚霜冻低温平均发生概率和强度最大的地区;冷空气在山坳低洼处易于堆积而又难以流出,加大了豫西山地、丘陵(最强的晚霜冻低温区)的降温幅度;晚霜冻低温EOF法的前3个模态分别表现出"北多南少"、"东北多西南少"、"东多西少"的特征,为河南省晚霜冻的主要特征;除受冷空气的直接影响外,晚霜冻还与天空状况(云、雨、雪、雾等)、冬小麦生长发育特征、前期土壤墒情、地形地理分布等有关.

Using the conventional meteorological observation data, agricultural meteorology data, and the frost disaster report in the past 41 years from 1971 to 2011, the study applied EOF （empirical or- thogonal function decomposition）analyses to extract the spatial and temporal characteristics of the late frost-low temperatures in Henan Province. The results demonstrate the largest frequency and amplitude of the late frost-low temperatures occur over the northern, western and eastern parts of Henan Pro- vince. Most of the strong late frost regions in Henan Province are mountainous and hilly zones, when cold air enters the lower-lying areas, it tends to accumulate and is hard to flow out, due to continuous cooling. There being more late frost-low temperature in the north, in the northeast and in the east, but less in the south, in the southwest, and in the west is the main distribution characteristics of the late frost in Henan Province. In addition the late frost damage is also affected by the weather condition （clouds, rain, snow, fog, etc. ） , the winter wheat growth period, and soil moisture in the early grow- ing period.