【作者】 朱晓炜；

【导师】 李栋梁； 李耀辉；

【作者基本信息】 南京信息工程大学 ， 气候系统与全球变化， 2011， 硕士

【摘要】 河西走廊地区是我国北方冷空气南下的重要通道,毗邻沙漠,受气候和地形的影响,是我国沙尘暴影响最严重的地区之一,对这一敏感区域进行观测,非常有利于沙尘暴的研究工作。本文利用民勤地区1971-2009年沙尘暴爆发时间的统计数据,对民勤地区沙尘暴年际发生频次的进行了研究。结合“4.24”沙尘暴过程,用站点监测、模式预警和遥感监测三种方法的结果进行了分析,得到如下结果：(1)民勤地区沙尘暴发生频次波动下降,呈5年和15年的周期性,在80年代中期下降趋势较明显。春季沙尘暴的发生次数最多,依次是夏季,冬季和秋季。(2)利用“4.24”沙尘天气过程中的站点监测资料,对地面温度、地面气压、相对湿度和风速的变化进行了研究。沙尘暴发生之前,地面温度较高,地面气压较低,相对湿度较低。沙尘暴发生之后,地面温度迅速下降,地面气压升高。相对湿度在沙尘暴的发生初期升高,在后期下降。地面风速的变化曲线和沙尘浓度的变化曲线一致。(3)利用T213资料和GRAES SDM模式对“4.24”沙尘天气进行模拟,通过和站点监测的地面温度、相对湿度、沙尘浓度的比较,模式结果能反映出相应要素的变化趋势,模式结果得到验证。利用模式结果,对民勤"4.24”沙尘过程前后的散度场和涡度场配置进行分析。沙尘暴发生之前,在民勤西北部即巴丹吉林沙漠,地面850hPa同时存在负散度中心和正涡度中心,此地地面有强烈的辐合运动。民勤处在正负散度和正负涡度的边缘地区。沙尘暴结束时,在巴丹吉林沙漠850hPa处有较弱的负散度和涡度中心,地面的辐合运动降低。巴丹吉林沙漠的辐合上升运动对民勤地区沙尘暴的爆发起着很重要的作用。(4)沙尘暴遥感监测系统根据沙尘的反射和辐射特性建立的沙尘指数,本文利用08、09两年的站点观测数据对遥感监测建立的沙尘指数进行了验证,沙尘浓度高的时刻沙尘指数也较高,沙尘指数能准确反映出沙尘强度的大小。并通过2010年的遥感图像,得到此时甘肃省中北部,宁夏中部,陕西省和内蒙古的交界处同时有沙尘天气的过境。更多还原

【Abstract】 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.更多还原