2006年北京一次持续浮尘天气过程的分析

使用NCEP/NCAR再分析资料对2006年4月7~11日北京浮尘天气过程的持续性进行分析,指出此次浮尘天气过程主要受500 hPa西西伯利亚冷涡、鄂霍次克海暖高压以及青藏高原高压脊影响;700 hPa有干冷空气不断向北京地区输送,冷平流和斜压性都很强,大风和沙尘暴发生在强冷平流区域;由于华北南部地区近地面至中低层存在弱的不稳定层结,容易产生弱的上升运动。在近地面低压前部偏东风的作用下将沙尘粒子向北京地区输送,北京地区上空大气在中低层基本处于中性或不稳定层结状态,沙尘粒子不易在北京上空沉降,造成较长时间的浮尘天气。

Analysis of a Durative Floating Dust over Beijing in 2006

By using global reanalysis data from NCEP/NCAR,the durative of a floating dust over Beijing during 7-10 in April of 2006 was analyzed.It was found that the impact systems of the floating dust weather were West Siberia cold eddy,Okhotsk warm high and Tibetan Plateau high ridge at the level of 500 hPa;the dry-cold air at the level of 700 hPa transferred to Beijing ceaselessly,and the cold advection and baroclinic instability were strong,the gale and dust storm occurred in the strong cold advection area;the weak instability stratification in surface layer and mid-low level in the south of North China resulted in weak ascending air flow,then transported dust particles to Beijing depending on the easterly wind in front of the surface low pressure.Because of the neutral or instability condition at mid-low level over Beijing,the dust particles were difficult to go down,and the floating dust weather lasted for four days.