Formation of low-level meso-scale southwest jet during seasonal rainfall

The meso-scale feature and energy budget of a low-level southwest jet were analyzed using the data collected during the heavy rainfall events that occ urred between July 20 similar to 27, 1998 over the basin of the Changjiang. And the dynamic mechanism for the formation and maintenance of the meso-sc ale low-level jet under the condition of the low-level heterogeneous large- scale south wind was investigated using a shallow water model. The results can explain the mechanism of the formation of the meso-scale jet in this ev ent and the importance of the heterogeneous large-scale horizontal motion i n the formation of the meso-scale jet.