The situation of the water vapor convergence center in 1999 is more east and south than in 1998, so the heavy rain region in 1999 is souther than in 1998.2.

• 水汽通量的势函数极小值区(最大辐合区)对应强降水区,并且暴雨区的水汽辐合是由半球尺度的水汽输送造成,这表明,即使对于该年背景的区域性大暴雨/洪水,它也必须从极大范围地区获得水汽供应。