中国北方沙尘天气原因探讨

我国是沙尘暴易发的国家,进入20世纪90年代以来,强沙尘暴有频率增加、强度加大、范围扩展、危害程度加剧的趋势。沙尘暴的发生危害范围亦逐渐从西北干旱经济落后区扩展到经济发达的北京、天津及华北平原区,近年来的沙尘暴造成了社会经济和人民生命财产的重大损失。受大气环流场和季风气候类型影响,中国冬、春盛吹西北风,强劲而干燥。发生沙尘暴的天数与大风日数和地面热力稳定程度相关,3-5月中国西北内陆地表增温大,是风力场和热力场极不稳定的季节,地表气候容易发生蠕动,沙尘暴便由此启动并易发。除自然要素外,不合理的人类活动也将诱发沙尘暴天气的发生,有些情况下还起到比自然要素更重要的作用。从生态地理区域的角度看,沙尘暴的源地在干旱和半干旱地区,由于大气环流的作用,影响到下风向的半湿润甚至湿润地区。无论何地干旱、半干旱地区都将存在沙尘暴发生的自然条件,而其下风向必将受到不同程度的影响,只是因为中国的季风气候,决定西北干旱、半干旱地区发生的沙尘暴必然影响东南部地区。在现有的科学技术条件下,人类所能做的就是调节自身的行为。因此,在沙尘暴源地实施生态建设是减缓沙尘暴发生的最重要措施,也是消除东部城市沙尘天气的主要途径。根据生态地理区域的特征,沙尘暴源地的干旱区、半干?

The Causes of Dust/Sand Storm in North China

China is a country with frequent dust/sand storm. The dust storms appeared the potential of frequency increasing, intensity strengthening, area spreading and damage rising since 90s of last century. In the recent years, damage of dust/sand storm speeded gradually from undeveloped area in the northwest to the developed areas in the north of China such as Beijing and Tianjin. Affected by atmosphere circumfluence and monsoon climate, arid and semi arid regions in northern China has strong and dry wind in winter and spring. Dust/sand storm development is controlled by temperature and humidity. During cold and humid period dust/sand storm has low possibility and weak intensity while warm and dry period it has high frequency and strong intensity. Except natural features, irrational human activities will accelerate dust/sand storms. In some cases they could play a more important role than natural features. In the point view of geo-ecoregion, dust and sand are from arid and semi arid regions. The storm affected leeward semi humid or even humid regions because of atmosphere circumfluence. Any arid and semi arid regions have the features for dust/sand storm happening. The leeward regions will be affected in different degrees. Only monsoon climate in China determines that dust/sand storm in arid and semi arid region of the northwest will certainly affect the southeast. According to science and technology conditions at present man can only do is to adjust his activities. That is to implement ecosystem construction in dust and sand source areas, which is most important measures for mitigation of the storms and is also many approaches for elimination of dust/sand weather in cities of the east. Because there are differences in an arid or semi arid region, the dust/sand storms root areas. Therefore, different measures should be applied in different regions for ecosystem construction according to the local features.