Interannual Variability Research Of Sandstrom In Minqin And The Comparative Analysis Of Its Monitiring And Warning Technology

Hexi corridor is the important channel in our country for cold air going to south. Adjacent to the desert, affected by climate and topography, the area is one of the most severe regions influenced by sandstorm. Observing this sensitive region is very conducive to further sandstorm's research work. Used the statistical data of storms broking out from 1971 to 2009, the annual frequency of storm was studied. Combined with "4.24" sandstorm process, we used site monitoring, mode warning and remote sensing monitoring to analysis. The results as followed:(1) the sandstorm frequency was decline and had 5,15 cycle fluctuations. In the mid-80's decline was obvious. Sandstorm occurring in spring was the most, in turn was the summer, winter and autumn. (2) Based on the site monitoring data, the ground temperature, ground pressure, relative humidity and wind speed were analyzed. Before sandstorm occurring, the ground temperature was higher, the ground pressure was lower, relative humidity is lower. After sandstorm occurring, the ground temperature dropped quickly, the ground pressure increased. Relative humidity rose in the beginning and dropped at the end. The ground wind speed changed consistent with the curve of sand-dust concentration. (3) Using T213 data and GRAPES_SDM mode, through simulating the "4.24" dust weather, we knew the model results could reflect the elements'changing trend, the model result was verified. The model results were used to analyze the vorticity and divergence fields. Before sandstorm occurring, BaDanJiL in desert that located in northwest of minqin had negative divergence center and positive vorticity center at 850 hPa. That mean the ground had a strong convergence movement. Minqin was at the edge of the region, which was between positive and negative divergence, which was between positive and negative vorticity. At the end of the sandstorm, there was a weaker divergence and vorticity center in BaDanJiLin desert at 850hPa, the ground of the convergence movement reduced. BaDanJiLin desert's vertical movement played an important role in sandstorm occurring in minqin. (4) According to sandstorm's reflection and radiation characteristics, remote sensing monitoring system established a sand-dust index. We verified the sand-dust index by sand-dust concentration from 2008 to 2009. Sand-dust index could accurately reflect dust strength. Based on the remote sensing image, we got that the middle of Ningxia, the north-central of Gansu, the intersection of Shanxi and Inner Mongolia had the dust weather.