[an error occurred while processing this directive] | [an error occurred while processing this directive]
A Modified Moist Ageostrophic Q Vector
YUE Caijun,SHOU Shaowen
Shanghai Typhoon Institute, China Meteorological Administration, Shanghai 200030； Laboratory of Typhoon Forecast Technique/China Meteorological Administration, Shanghai 200030;School of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044
Abstract The quasi-geostrophic ${\boldsymbol Q}$ vector is an important diagnostic tool for studying development of surface rainfall associated with large-scale weather systems and is calculated using data at single vertical level. When ageostrophic Q vector was introduced, it required data at two vertical levels. In this study, moist ageostrophic Q vector is modified so that it can be calculated using data at a single vertical level. The comparison study between the original and modified moist ageostrophic Q vectors is conducted using the data from 5 to 6 July 1991 during the torrential rainfall event associated with the Changjiang-Huaihe mei-yu front in China. The results reveal that divergences of original and modified moist ageostrophic Q vectors have similar horizontal distributions and their centers are almost located in the precipitation centers. This indicates that modified moist ageostrophic Q vector can be used to diagnose convective development with reasonable accuracy.
