The Cold-Frontal Circulation in the Upper-Level Westerly Jet and Low-Level Southerly Jet
高空西风急流和低空南风急流中的冷锋环流

The influence of different background currents on the circulation of a dry cold front is investigated by using a primitive equation model. The calculations show that the upper-level westerly flow plays a main role in the development and enhancement of the cross-frontal ageostrophic circulation and vertical motion in the frontal zone. The cross-frontal circulation also depends on the low-level southerly flow. However, its effect is much weaker than the westerly flow. The westerly current with strong vertically shear is advantageous to generate a stronger cross-frontal circulation and upward motion in the frontal zone. In addition, the cross-frontal circulation is related with the regions of small Richardson number.