中国北方沙尘暴频数演化及其气候成因分析

CHANGE IN DUST STORM FREQUENCY AND THE CLIMATIC CONTROLS IN NORTHERN CHINA

  • 摘要: 利用地面气象观测资料,分析了中国北方1954~2001年、季沙尘暴发生日数的演变规律及其与风速、相对湿度、降水、气温和干燥度的相关关系。结果表明,中国北方沙尘暴发生日数在1954~2001年呈波动下降的趋势,春季下降趋势最明显。沙尘源区的气候要素对北方沙尘暴发生日数具有比较明显的影响,其中风是影响较大的因子。平均风速和大风频率增加(减少)均有(不)利于沙尘暴天气的形成。气温与沙尘暴日数呈显著的反相关关系,反映了北方温度升高可能通过大气环流间接地抑制了沙尘暴的发生。降水增加对沙尘暴发生也有一定抑制作用,尤其春季和前冬沙尘源区降水多寡对沙尘暴的发生有着重要的影响。北方沙尘暴频数与沙尘源区的相对湿度或干燥指数也存在较明显的相关关系。在过去的近50a内,造成中国北方沙尘暴频率显著下降趋势的直接自然原因是:沙尘源区和发生区平均风速和大风日数的减少、主要沙尘源区降水量特别是春季和前冬降水量的增加、以及由于源区降水增加引起的大气和土壤湿润程度的改善。

     

    Abstract: Duststorm is one of serious environmental problems in northern China.Based on the surface observation data,tendency of days with duststorm and the relationship between annual and seasonal days with dust storm and the climatic factors,such as wind,relative hum idity,air temperature,precipitation and dry ness index,were analy zed.The results show that days with duststorm had been fluctuant decreasing during 1954-2001,especially in spring.Climatic factors in dust resource areas obviously affect the occurrence and development of duststorm.Relationship analysis shows that wind is a key factor to the occurrence of dust storm in the study area.Bothaverage wind speed and days with strong wind are import ant for development of duststorm.Negative correlation between air temperature and days with dust storm was also found,indicating that a warming north will lead to a decrease in days with dust storm.Increase of precipitation over the source areas of dust during the past 50 years or so mighthave restrained the development of duststorm.The precipitation in winter such as snow,will melt in spring,and will be useful supply to wet the earth surface in the next spring.So the total precipitation in spring and the previous winter is much more important.Relative humidity generally plays a similar role with precipitation.Dryness index,which incorporates the effect of precipitation and temperature,was correlated as well with duststorm frequency,and it was found to be a good indicat or for occurrence of dust weather phenomenon.

     

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