The Improvement For Deposition Nucleation Parameterization And The Numerical Simulation Research On The Effect Of Aerosol On Thundercloud Electrification

Based on the existing two-dimensional model of convective clouds which has added a new ice nuclei parameterization, a optimization scheme has been put forward. Combining the sounding data, A thunder cloud has been simulated to study the effect of the ice nucleation on the cloud microphysical process, precipitation and electrification, which can offered theoretical support to the study on the charge process of a thunder cloud in future works. The mian conclusions of the paper follow as(1) Compared with the old scheme, the spread of ice crystal in a thunder cloud which based on the optimization scheme has changed. The ice crystal mainly occurs around the range of ≤-13.8℃ while -40～0℃ in the old parameterization scheme. Besides, A dramatic reduction on the mixing ratio of ice crystal has been found. According to DeMott’s paper (2010), the deposited nucleation of aerosol in the old parameterization scheme largely overestimates the observed IN concentrations.(2) In addiction, the simulation also indicates the change on the temperal-spatial distribution of other hydrometeors. Due to a dramatic reduction on the mixing ratio of ice crystal ranged below -20℃, the consumption of cloud water and water vapor is weaker than the old scheme. On the other hand, the collection efficiency of cloud water and the coalescence growth of raindrops are intensified. Moreover, when cloud drop and rain drop’s content are enhaced, the probability of collision between cloud droplet and graupel also increses.(3) The result indicates both the solid precipitation and liquid precipitation displace significantly earlier, and the cumulative precipitation or total rainfall is enhanced from 1.94 mm up to 10.8 mm.(4) The optimization scheme caused a dramatic reduction on the mixing ratio of ice crystal ranged below-20℃. The probability of collision between ice crystal and graupel is largely weaken. Moreover, the noninductive rate is also inhibited. However, when considering aerosol heterogeneous effect and its competition between homogeneous freezing nucleation, the noninductive rate is laegely enhanced ranged of>-25℃.