The Study Of Method Of Cloud-retrieval With Satellite Data And The Distribute Characteristics Analyses Of The Cloud Covered On The Qilian Mountains

In this paper, a suitable cloud diction method must be found with GMS-5 satellite data at first. So the method of multi-channel synthesis algorithms was established. It got a good outcome of multi-channel synthesis algorithms contrasting with the visible picture, but it has a shortcoming that is it difficult to distinguish the cloud from the firn covered on the earth. Many area of Qilian Mountains is covered by the firn and glacier. So it must be found a new algorithms to solve this problem. Useing the infrared channel one and water vapor channel the method to distinguish cloud from firn that was established. With the algorithms established the satellite data was dolt and the outcome analyses, the character which is the characteristic of probability distribution of cloud cover and spatial distribution of total efficient cloud cover of satellite data over Qilian Mountains was got. That is: the trend of the total cloud cover is the cloud distributed in west is more than that is distributed in east, and it is more distribute in south than in north. Along the mountains, it is obvious that cloud cover is drop off from west to east. The spatial distribution of total cloud cover has obvious change in different seasons. In the west of the 98°E, More area is covered by cloud, the high value center mainly appears in the elevation higher area. There is a high value center nearby Chaganebotuling mountain range, south range of Shule mountain and south range of dangriver mountain all the time, and a lower value center often appear nearby north of dangriver south-mountain and Halalake north-mountain. In the middle part of Qilian mountains, there are lots of cloud distributed in muli also. In the west of 99°E, the main trend that cloudage distribution decreases from northwest to southeast, and there is a high value center at the Lenglong mountain range, and there is less cloud cover near the Qinghai lake where always maintained a low value center. Furthermore,the trend which the cloud cover of Qqilian mountains changed with the time analyzed , and with the geographical position the distribution of cloudage was analyzed. It is verified preliminarily whether the second snowfall or rainfall exist, through the change of the characteristic of cloudage with the height in glacier study. Using the result of satellite data analyzed, which combines with data of the total cloudage and precipitation over 50 years, a study of the relations of the space-time and amount distribution of cloudage with changing of water vapor, precipitation, and monsoon climate over Qilian Mountains has been carried out. The results indicate that with influencing by monsoon and terrain, the distribution of cloudage appears relevant change with the water vapor changing.