Dynamic Analysis on Formation of a Torrential Rain

The paper analyses the developing characteristic of a torrential rain in Wuhan,and theoretically discusses the dynamic mechanism of the torrential rain.The results show that the low-level jet(LLJ) occurred before the torrential rain,and when the torrential rain is the strongest,the LLJ is also the strongest.The existence of non-thermal wind gradients on the right side of the entrance region of the upper level jet (ULJ) and the left of the LLJ,leads to the unstable amplitude of mesoscale waves.The unstable amplitude increases towards the torrential rain area,which tallies with the maximum amplitude area of waves due to the overlapping of the two unstable waves.Under the circumstance of the coupling of the upper and low level jets,the non-thermal wind mesoscale convection-symmetric instability might be one of dynamic mechanisms resulting in torrential rain.