大气-海洋环流异常对山西省沙尘天气的影响

Effect of Atmospheric-ocean Circulation Fluctuation on the Frequency of Dust Weather over Shanxi Province

利用山西省1961-2003年15个站的月沙尘天气日数资料,对沙尘天气发生的频率与大气-海洋环流因子SOI,NAO,PDO和AO指数的关系进行了分析。结果表明:与山西平均沙尘日数变化关系比较显著的因子有PDO和AO指数,且均呈负相关。在这些环流指数偏高的年份,对应山西少沙尘天气;反之,则多沙尘天气。分析还发现,山西的沙尘天气事件与SOI指数有显著的滞后两年的正响应关系。与AO和PDO有显著负相关的站点主要分布在西北部到中东部及西南部,与SOI有滞后两年正相关的站点主要分布在中东部和东北部。在此基础上,讨论了大气-海洋系统振动对山西沙尘天气产生影响的可能机制。

Dust weather occurs usually over the semiarid, arid and desert areas. Days of occurring dust weather are related to the background of large-scale circulations to a great extent. It is possibly attributed to atmospheric-ocean fluctuation. In this paper, the relationship between annual days of occurring dust weather including windblown sand and sandstorm over Shanxi Province during the period from 1961 to 2003 and indices, i. e. , NAO, PDO, AO and SOl indicating atmosphere-ocean system fluctuation is analyzed. The annual days of occurring dust weather were calculated by using the monthly data from 15 meteorological stations in the province. Correlation coefficient is used to describe the close degree of dust weather and atmosphere-ocean circulation factors. The results show that the quasi-periodic variation of global atmosphere and oceans might play an important role in the development and change of dust weather events in the region. It is found that there are the significant negative correlations between annual days of occurring dust weather over the study area and the PDO and AO indices. It is also found that there is a significant positive correlation between 2-year-lagged annual days of occurring dust weather and SOI index. The stations with significant ＇negative correlation between the annual days of occurring dust weather and the PDO and AO indices are mainly located in the northwestern, central-eastern and southwestern parts of the province, but the ones with positive correlation between the 2-year-lagged annual days of occurring dust weather and the SOI index are mostly distributed in the central-eastern and northeastern parts. On which the possible mechanisms of effect of atmospheric-ocean fluctuation on dust weather over Shanxi Province are discussed.