东北地区不同季节持续低温指数时空变化特征及其对区域温暖化的响应

The Consecutive Cold Day Index and Its Response to Regional Warming in Northeastern China

采用东北地区包括黑龙江、吉林、辽宁3省73个常规气象台站1961年-2005年日最低温度和平均温度观测资料,分析近45年来不同季节CCDI变化特征及其对区域温暖化的响应,结果表明:①东北地区年CCDI呈下降趋势,并且春、夏、秋、冬季CCDI具有一致性降低的特征。不同季节CCDI降低的幅度并不一致,冬季降低幅度最大,夏季最小;②东北地区年CCDI大致表现出南、北降低缓慢,中间降低较快的分布形态。不同季节CCDI降低的空间分布规律与年CCDI降低的规律基本一致,仅数值大小上存在差异;③东北地区年平均温度呈现出显著的升高趋势(p<0.01),平均气候倾向率为0.38°C/10a,并且春、夏、秋、冬季平均温度具有一致性升高的特征。不同季节的增温幅度以冬季最大、夏季最小;④就年及不同季节总体而言,平均温度与CCDI为负相关关系(p<0.01)。季节间温度升高的差异大于CCDI降低的差异,不同季节内CCDI的降低对该季节平均温度升高的响应强度不等,单位温度上升造成CCDI降低的幅度,冬季大于夏季。

Patterns in temperature variation are changing in many parts of the world. Low temperatures affect the growth of many crops growth.A new index for the effect of extreme low temperature on crop damage, called the consecutive cold day index （CCDI） is presented here. The spatio-temporal patterns of CCDI and its response to regional warming were analyzed using daily mean and extreme low temperature for 73 stations in northeastern China from 1961-2005. A decrease in annual CCDI was found for spring, summer, autumn and winter, with the largest drop in winter and smallest in summer. The rate of decrease in annual CCDI was larger in the north and south, compared to the middle of our study area. The mean annual temperature increased by 0.38 ~C/ 10a. Negative relationships between mean temperature and CCDI were found for all time scales. The difference in the rise of the mean temperature was larger than the drop for CCDI in spring, summer, autumn and winter. The biggest decline in CCDI was found in winter. Under global warming and, it is becoming more prevalent to plant late maturity crops in northeastern China, and this region has sustained increasing chill damage in recent years. After the late 1990s, annual mean temperature rose, and annual CCDI fell, gradually, but the summer mean temperature and CCDI followed an opposite pattern. We warn that the trend towards planting late maturity crops in this area should slow, until we better understand patterns of cold damage and the impact on crop yield.