我国北方TOMS气溶胶光学厚度与地面沙尘天气频数的比较

Comparison between TOMS Optical Depth Index of Aerosol and Dust Weather Frequency in North China

利用卫星监测和反演沙尘天气频率或沙尘气溶胶光学厚度,检验卫星监测和反演结果是否与地面观测一致。采用地面观测记录获得全部沙尘天气事件频数(DF)资料,对1979—2002年TOMS(臭氧总量绘图系统)反演的气溶胶光学厚度指数(AI)进行检验分析。结果表明:1 AI高值区基本与我国北方地面观测的沙尘天气频数高值分布区一致,两者均在我国西北部极端干旱的盆地和高原地区出现最高值,相对低值一般分布在气候湿润的东部地区,但东北平原和华北平原AI值相对较高,冬季尤其明显,与地面沙尘观测差异很大;2 AI和DF年内变化也具有很高的一致性,均在春季最大,4月达到峰值以后减小,但前者在冬季12月和1月出现次高值,而后者冬季为全年低谷;3相关性分析表明,AI和DF相关系数一般在夏季最大,冬季最小,年和季节的相关系数具有随时间呈下降的趋势;4 TOMS AI数据在反映我国北方沙尘天气频数时空变化特征方面,区域上西北干旱区效果最好,东部季风区的华北和东北较差;季节上夏季、初秋和春季较好,冬季效果较差。同时还对AI和DF资料时空分布差异的可能原因及其潜在应用意义进行了讨论。

It is necessary to examine whether the satellite monitoring results are consistent with the ground-based observations if satellite data are used in studying dust weather frequency （DF） or dust aerosol optical thickness. In this paper, the dust weather frequency data from the ground-based observations and the values of aerosol optical thickness index （AI） from TOMS for the time period of 1979 -2002 were analyzed. The results are as follows： （1） The areas with high AI value were basically consistent with those with high DF value in north China, these areas were located in the extremely arid basins and plateaus in northwest China; the areas with low value were generally distributed in humid east China except the Northeast Plain and North China Plain where the AI value was relatively high, especially in winter; （2） Change of monthly AI and DF values was highly consistent, the highest AI and DF values occurred in spring, the second highest AI values occurred in December and next January ; （3） The correlation coefficient between AI and DF was generally the highest in summer but lowest in winter; （4） The TOMS AI data could be used to ideally reflect the spatiotemporal patterns of DF in arid northwest China but poorly in north China and northeast China.