Tang Jie, Liu Xiaoli
Nanjing University of Information Science and Technology, Key Laboratory of aerosol and cloud precipitation in China
Meteorological Administration, Nanjing, Jiangsu 210044
(Received January 07 2018, accepted May 25 2018)
Abstract Three boundary layer parameterization schemes (MRF,UW,YSU) in mesoscale numerical model (WRF) are used to
simulate a severe convective weather in Zhejiang on November 9, 2009 without considering the rainwater evaporation term and
considering the rainwater evaporation term. The numerical simulation results of macroscopic and microscopic physical
mechanisms of strong convection were compared. The results show that without considering the evaporation of rainwater, the
rainbands simulated by the three boundary layer schemes are narrower, hourly precipitation is smaller, convective monomer moves
slower, and the precipitation overlap area is more. The simulated radar reflectivity intensity is significantly reduced and the echo
band is narrower. Whether rain evaporation is considered or not, the YSU scheme simulates the strongest precipitation and radar
reflectivity, MRF scheme is close to it and the UW scheme is the weakest. By analyzing the macro conditions of convection
development, it can be seen that under the condition of considering the rainwater evaporation, high and low altitude divergence
configuration simulated by the three boundary layer schemes is better, the water vapor transport is more abundant, updraft and
downdraft are stronger, providing more favorable conditions for the occurrence and development of strong convection. Whether
rain evaporation is considered or not, the water vapor conditions and high and low altitude divergence configuration simulated by
the YSU scheme are better, results simulated by MRF scheme is similar to YSU scheme. The convection generation condition
simulated by the UW scheme is the weakest of the three schemes. Under the condition of considering the rainwater evaporation,
more hydrogel particles simulated by three boundary layer schemes, and stronger updraft, which is more conducive to development
of convection. Whether rain evaporation is considered or not, the MRF and YSU schemes can simulate more rain, mainly because
the vertical movement of the airflow is stronger, and more cloud water becomes cold cloud water under the strong ascending
airflow, and more cold water frozen with graupel to form graupel, graupel melts to produce more rain. The UW scheme have poor
macroscopic conditions, and the updraft is weaker. Cold cloud water is less, and cold cloud water and graupel are less frozen,
resulting in less rainwater content