中国西北地区干枯湖泊沉积与东亚沙尘天气

ncient Juyan Lake is located at the Alxa Plateau, western Inner Mongolia of China. Samples were collected from lacustrine deposits in ancient Juyan Lakes, active sand dune around, surface soil of sandy grassland and ancient abandoned land. By means of analyzing their grain-size component, the influences on sand-dust weather are discussed. The grain-size measurement for ancient Juyan lake indicate that the particles below 10 μm account to more than 64 % of the surface lacustrine deposits of dried lake-bed, which could be transported thousands of kilometer away in the air under the condition of normal storm. It means that the dust which came from dried lake-bed in the northwestern China could sweep over the north of the East Asia under the action of the storm. Sand-dust storm is a mixture of sand storm and dust storm. For the northwest wind usually happened during winter and spring, so the sand-dust storm and blowing-sand weather formed in the northwestern China then. Sand and dust were carried into the air current from the desert, sandy land and sandy grassland when encountered with strong wind. Yet for the limit of blowing height and transporting distance of coarse sand, the coarse sands deposit and dust were still transported in the air as the wind went slow down little. New sand and dust are added when strong wind went by another sand area. Accordingly, sand-dust storm move forward to southeast by means of relays.