基于MODIS的雪情监测及其对农业的影响评估

2009年11月中旬,中国中部地区出现了大范围持续低温、雨雪、冰冻天气气候事件,造成了积雪灾害。本文利用连续多天的MODIS遥感数据,通过计算归一化差分积雪指数（NDSI,Normalized Difference SnowIndex）分析了北京、河南、河北、湖北、山东、山西、陕西7个地区的积雪状况,对积雪发生的时空特征进行了动态监测,并对监测省份农业受到的影响进行评估。结果表明：监测区整个降雪过程积雪面积呈单峰型变化,11月15日积雪面积最大,15日以后积雪面积开始减少,24日监测区积雪基本融化;山西省为本次降雪过程的核心区域,累计积雪总面积为62.89×10^4km^2,陕西、河南、河北省次之,分别为40.10×10^4km^2、37.62×10^4km^2、37.58×10^4km^2,山东、湖北、北京受积雪覆盖影响较小,积雪总面积分别为10.42×10^4km^2、8.52×10^4km^2、0.42×10^4km^2;监测期间油菜作物均处于出苗期,持续积雪覆盖会对其产量造成一定影响。已进入越冬期的冬小麦,稳定的积雪覆盖会产生积雪融水,进而土壤墒情得到改善,有利于作物来年生长。尚未进入越冬期的冬小麦抗寒能力较差,持续低温积雪对其生长及产量造成不良影响。

Monitoring and Assessment to Snow and Its Impacts on Agriculture Based on MODIS

Continuous low temperature,heavy snow and freezing emerged in Central China in mid-November 2009.The situation and impact of snow was analyzed and evaluated based on MODIS date and NDSI.The results showed that the curve of snow area changed as a single peak,the maximum value was on November 15th.The key snow area was in Shanxi province with 62.89×10^4km^2,following Shaanxi,Henan and Hebei province with 40.10×10^4km^2,37.62×10^4km^2,37.58×10^4km^2 respectively.No more than 10.5×10^4km^2 in Shandong,Hubei and Beijing.The rapeseed has been negative impact due to seeding stage.However,the winter wheat could get more moisture during over-wintering stage.