By using the reanalysis data ofNCEP( 1°×1°) and the radiosonde and surface observations aswell as the Doppler radar products, the features of a strong dust storm occurred on 13 June 2008 in theHexiCorridor are analyzed. Results show that the upper cold airmoved fast and overlapped on the surface cyclone resulted inmeso-scale convection system developing fast. The dry-warmlid at the level of500-540 hPawas advantageous to the instability energy accumulation at low level and itwas importantomen for the strong convection weather.The convection system took place firstat the low layerbefore the sandstorm outbreak, then quickly developed tomiddle layer. The sandstorm occurred in theweak echo areawhichwas in frontof the strong echo and in the adversewind region of radial velocity

By using the reanalysis data of NCEP (1°×1°) , the dry intrusion characteristic of a strong dust storm p rocess occurred in the Hexi Corridor from Ap ril 9 to 10, 2006 was analyzed. The results show that the high potential vorticity, dry air from the upper level of troposphere extended downwards and southwards, which increased the vertical component of the vorticity on the steep iso - entropy p lane and p romoted the rap id development of the low level cyclone, resulted in a low level jet and the intensive convergence in the
boundary layer.

Based on FY - 2 infrared images and the reanalysis data for six hours ofNCEP (1°×1°) , the heavy dust storm p rocess occurred on 13 Ap ril 2007 in the middle west part of Hexi corridor is analyzed, particularly the cloud head of the descending jet was tracked and the gravitational instability, conditional symmetric instability and conditional instability are diagnosed in detail. Results show that a high speed descending jet resulted in this heavy dust storm and the jet triggered strong convection in frontal region, and conditional instability occurred in themiddle part of troposphere first, then developed downwards. The release of conditional instability energy at the level of 700 hPa caused rap id development of convective circulation in boundary and brought on this heavy dust storm.