兰州降尘的气候诊断分析  

Climate Diagnosis of Lanzhou Dustfall

作　　者：李旭[1] 周海[1,2] 王式功[1] 尚可政[1] 杨德保[1] 

机构地区：[1]半干旱气候变化教育部重点实验室兰州大学大气科学学院 [2]95903部队

出　　处：《安徽农业科学》2010年第3期1339-1342,1420,共5页Journal of Anhui Agricultural Sciences

基　　金：国家自然科学基金项目(40675077);国家科技支撑计划(2007BAC03A10)资助

摘　　要：利用兰州降尘资料及NCEP/NCAR再分析资料,采用气候诊断分析的方法对兰州降尘进行分析。通过对60年的垂直运动场及涡度场诊断分析发现,兰州地区冬季中低层下沉运动强而明显,且兰州冬季处于采暖期,在沙尘暴及盆地气候影响下,兰州冬季降尘明显;春季兰州处于下沉运动边缘区,上升运动较弱,但沙尘源区存在上升运动,有利于尘粒向上输送,兰州位于沙尘暴多发区河西走廊下风向,外来沙尘加速粉尘沉降,造成兰州春季降尘居各季之首;夏季兰州受地面加热源影响,低层上升运动明显,由于雨水对颗粒物的清洗作用,兰州夏季降尘较秋季为高;多年平均涡度场形势与多年平均垂直运动场存在较好的一致性,较为直观地反映了各季影响兰州的主要系统的演变情况,合理地解释了兰州地区降尘季节分布演变规律。By using the NCEP/NCAR reanalysis data, climate diagnosis method was used to analyze the characteristics of Lanzhou dusffall. After analyzing the 60 years＇average vertical velocity field and vortieity field, the following conclusions were gained, in winter, the middle and low level descending motion were strong and evident. Moreover, during the heating period, because of the impact of sandstorm and basin climate, the dustfall in winter was evident. In spring, Lanzhou was the margin of descending motion area, the ascending motion was weaker. But for the reason that there existed ascending motion in the dust source region which made for the dust ascending, and Lanzhou located in the leeward region of Gansu Corridor where sandstorm frequently occurring region, adventives dust will speed dust falling, dustfall was the heaviest in spring compared with other seasons. In summer, the low level ascending motion was obvious in Lanzhou for the effect of the earth＇s surface heating source. Since the rain can clean out the particulate matter, the dustfall was obvious in summer than in autumn. There existed good coherence between the multiyear average vorticity field situation and vertical motion field. It intuitively reflected evolvement states of the main systems which affected Lanzhou in different seasons, and it reasonably explained the evolvement rules of dusffall distributing in Lanzhou area.

关 键 词：降尘 气候诊断 垂直速度 涡度 

分 类 号：S162[农业科学—农业气象学]