Using ERA-5 hourly reanalysis data,radar data,conventional sounding data and intensive automatic stations data,two dif-ferent heavy rains in northern Shaanxi on July 21,2019 and August 4,2020 were compared and analyzed.It shows that(1)The persist-ence of heavy precipitation was the direct reason why the accumulated precipitation in"0804"process was greater than that in"0721"process.(2)Composite radar reflectivity showed a ENE-WSW oriented stratocumulus echo moved eastward across northern Shaanxi in the process of"0804"at night which led to the quasi-stationary rainbands.(3)The coupling of upper and low level jet,the path of low vortex and water vapor transportation played important roles in causing the difference of intensity of the two precipitation processes.The upper level jet at 200 hPa in the process of"0804"stayed stable and the intensity of low level jet at 700 hPa was stronger than that in the pro-cess of"0721".The torrential rain area in the process of"0804"was closer to the center of the vortex which provided adequate water and water vapor convergence lifts.(4)The triggering mechanism of convection in two processes is different,and the strong easterly wind on the ground in the"0804"was more conducive to topographic uplift.
RainstormNorthern ShaanxiUpper level and low level jetVortexWater vapor transportation
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NSTL
万方数据
