2005年我国沙尘天气的若干特征分析

The Characteristics of Sand and Dust Weather Events in China in 2005

2005年我国共出现了11次沙尘天气过程，其中沙尘暴4次、强沙尘暴1次，是沙尘天气频次明显偏少、强度明显偏弱、影响范围明显偏小的一年。春季（3-5月）的沙尘天气过程明显少于近6年的平均值，沙尘暴和强沙尘暴过程远少于2000、2001和2002年，该季累计出现的沙尘天气、沙尘暴总站日数较2000--2005年同期平均水平偏少4--7成，创近6年的最低值。分析表明，2004／2005年冬季我国北方地区雨雪偏多，地表积雪偏多，土壤表层湿度偏大，是导致2005年沙尘天气明显偏少、强度偏弱的主要原因。此外，冬末春初北方气温偏低，土壤解冻晚，延迟了沙尘天气的发生，造成早春沙尘天气显著偏少，沙尘多发期偏晚。

In 2005, totally 11 sand and dust weather processes including 4 sand and dust storm processes and 1 severe sand and dust storm process occurred in China, when the frequency of sand and dust weather is obviously few, the intensity is obviously weak, and the area affected is obviously small. The sand and dust weather processes in the spring （from March to May） are obviously less than the mean values in the recent 6 years, the sand and dust storm and severe sand and dust storm processes are far less than those in 2000, 2001, and 2002, respectively. The total number of sand and dust weather days, as well as sand and dust storm days, is four to seven tenths less than normal in this spring from 2000 to 2005 which is the smallest value in the recent 6 years; The results show that there are more precipitation, more surface snow cover and larger humidity of soil layer in northern China in winter in 2004/ 2005, which are the main reasons for the obviously less sand and dust weather with weaker intensity in 2005. In addition, at the end of last winter and the beginning of this spring, the temperature in north China is relatively low and the soil defrosts late, which delay the occurrence of sand and dust weather and cause the few sand and dust weather in early spring and dust high-frequency period is late.