沙尘暴传输机理及源地环境特征

对沙尘暴的发生、传输机理及沙尘暴源地的环境特征进行了研究.结果表明,沙尘暴的发生与地理环境、地表土质、气候条件和地表植被状况等自然因素密切相关.裸露于地表的沙尘是形成沙尘暴的物质基础,降水稀少、空气干燥是沙尘暴发生的重要气候因素.地面上升的热气旋和大气的环流运动是地表沙尘暴发生和传输的动力.沙尘粒子的传输方式有蠕动、跃迁和悬浮3种.沙尘的传输距离和方向与大气环流的变化情况直接相关.沙尘暴源地一般位于大陆腹地,地域宽阔、平坦.地表土质多为沙砾、沙质土壤,地表土层裸露,土质干燥、疏松.沙尘暴源地的植被稀疏,气候的共同特征是全年降水稀少,空气干燥,冬季和春季大风天气频频出现.近年来人为的破坏活动也加剧了沙漠化的进程.

STUDY ON TRANSPORT MECHANISM OF SAND-DUST STORM AND THE ENVIRONMENTAL FEATURES OF ITS SOURCE GROUND

In the present paper, the origin, transport and the geographical environment of sand-dust storm are investigated deeply. The results show that the origin of the sand-dust storm depends mostly on the natural factors such as soil feature on the ground, climate condition and vegetation states on the ground. The dry and loose sand-dust particles on the recovered land are the base material forming sand-dust storm. Rare rainfall and dry air are the climate factors by which the sand-dust storm could formed. The hot cyclone is a starting force of sand-dust. The atmospheric circulation is the transporting force of the sand-dust storm. There are three transport patterns of the sand-dust particles on the ground. They are wriggling, transition, and suspension. The distance and the direction of sand-dust transport depend on the atmospheric circulation. There are the source grounds of sand-dust storm mostly in the hinterland in China. There are some characters in the area of the source grounds of sand-dust storm such as wide and plain lands, grit and sand composted soils, uncovered, dry and loose soils on the ground. There is not nearly vegetation in the source grounds of sand-dust storm. The climate of the source grounds of sand-dust storm is dry, and the rainfall is rare. There is strong wind in winter and spring. The human activities make the desert areas become larger than before and the sand-dust storm become more and more serious.