2006年两次影响北京的沙尘天气对比分析

利用卫星、再分析(NECP)、地面观测等多种资料,针对2006年3和4月影响北京的两次沙尘天气过程,就天气过程形势、云系演变以及沙尘传播和沉降进行分析.前者对北京上空的沙尘天气一扫而过,后者对北京的影响则是遍地黄沙.对比分析表明:1)强沙尘天气过程是蒙古气旋所引起的,沙尘天气起源于中蒙边境、内蒙古西部,在河套地区北部鄂尔多斯高原以及浑善达克沙地得到加强,并随着高空西北风将沙尘输送到华北、渤海、黄海北部一带.卫星遥感监测技术不仅可以有效地监测到沙尘天气的发展演变过程,也能有效地监测到沙尘的覆盖范围和沉降区;2)导致4月16～17日华北东部严重沙尘沉降现象的原因是地面冷锋静止于华北中部地区,距地面1 km以上的浮尘层稳定覆盖华北东部和渤海等广大区域的主要原因,是边界层中尺度涡旋对低空冷锋的阻挡作用;冷锋云系在东移发展过程中,受到日本海上空涡旋云系的顶推阻碍,其结构发生变型瓦解.

Comparison between Two Dust Weather Process Effecting Beijing in 2006

With satellite data,NCEP reanalysis data,and observation data and so on,weather process,cloud variation,dust transport and subsistence are analysed during those two dust storms happened in March and April 2006,respectively.The influence coming from the first one was just passing by,but the latter one brought severe yellow sand into the whole Beijing.Though the dust process from 16 to 17 April,which was in the early period,was not the strongest in the spring of 2006,it caused a very negative social influence.The analysis indicates that 1) strong dust process was caused by Mongolin cyclone and dust source was from the border between China and Mongo,and western inner Mongolia,and strengthened in northern Hetao region,Ordos plateau and Hunshandake sandland.Dust was transported to Northern China,Bohai sea,and northern Huanghai sea with the help of high-level wind.Satellite remote sensing technique not only can monitor the development of dust process,but also can detect the region covered by dust and estimate the value of subsidence.2) the main reason for that during the dust process from April 16th to 17th,the dust layer covered east part of Northern China,Bohai sea and larger area,is that in the boundary layer middle-scale vortex stopped low-level cold front;cold front clouds were obstacled by the scroll clouds staying over the Japan Sea during moving eastward,so the structure of cold front clouds was twisted and collapsed,therefore,severe dust subsidence occurred over Northern China.