Numerical Simulations Of Two Deep Convective Systems In Hubei Province And The Comparison Of Five Micro-physical Schemes

Hubei Province is located in the mid-latitude inland areas.In spring and summer, deep convective weather events occur frequently. Due to the current lack of effective means to observe convective weather, the numerical simulation is produced to analyze the development of deep convective clouds. Two cases of deep convective weather occurred on April 15,2007 and May 23,2013 in Hubei province were simulated based on WRF model with 5 different micro-physical schemes. The characteristics of macro-physical and micro-physical process in the development of clouds and precipitation mechanisms simulated by these schemes were discussed and analyzed.In the macroscopical background of a ridge line and two through lines at high altitude 500 hpa, the appearance of small step through lines makes the northwest airflow built over the region of Hubei province, the air becomes dry and cold,and in a unstable status. There is warm moist airflow from south in the low altitude and meet with the northwest cold air, the water vapor accumulation in the local palace, airflow convergence and lift at the same time, which has caused the strong convection weather.MY (Milbrandt-Yau) scheme could nicely simulates the precipitation region and hail in land at the same time.Through the analysis of distribution and evolution characteristics of hydrometeors in cloud of both cases simulated by MY,It is found that most of the cloud water in two cases are delivered to above 0℃ layer, forming a large number of ice crystals at the cloud top, and there is more rain formed below the graupel particles;In Xiaogan case(Casel) and Shiyan case (Case2), the precipitation are mainly comes from graupel melting, followed by autoconversion of cloud to rain and collection of rain to cloud water, but this is much smaller than the graupel melting; The main source of graupel is the accretion of rain by ice,and the main growth is the collection of cloud water and rain by graupel.In Case One,graupel collects more cloud water than rain,but in Case Two,they are similar to graupel growth.In both cases,hail mainly comes from the accretion of graupel to graupel and the accretion of graupel to rain,and grows with the collection of cloud water.Based on the analysis of the five schemes results,we can found that Lin scheme and WSM6 scheme simulated lower cloud water mixing ratio than others.Ice crystal mixing ratio simulated by MY scheme is very high, the maximum are respectively 3.9 g/kg and 2.0 g/kg in case one and case two,but snow are rarely.The content of the snow are relatively abundant by WSM6, WDM6 and Morrison schemes simulated,the maximum are above 1.8 g/kg.Graupel (hail) mixing ratio of the five micro-physics were similar.Rain mainly produced by melting of graupel in the Lin scheme,WSM6 scheme, WDM6 scheme and Morrison scheme. For Casel, the source of rainwater in Lin scheme also has two ways that cloud water collection by rain and auto-conversion from cloud water to rain water. In WSM6 scheme and WDM6 scheme, the melting of snow, cloud water collection by rain and auto-conversion from cloud water to rain water also has a grate contribution to the source of rainwater. In Morrison scheme, a large part of the growth of rainwater comes from cloud water collection by rain except the melting of graupel, also the the melting of snow is a small part of contribution to the source of rainwater. The Case2 is similarity to the Casel in the simulation of the source of rainwater in Lin scheme. The second source of rainwater is snow melting in WSM6 scheme, snow melting and cloud water collection by rain in Morrison and auto-conversion from cloud water to rain water in WDM6.In Case One,the main source of the graupel with Lin scheme is the accretion of ice and snow to raindrop, and the main growth is the collection of cloud water and snow by graupel.The graupel of WSM6 scheme also mainly comes from the the accretion of ice and snow to rain,but the graupel of WDM6 scheme mainly comes from accretion of snow to rain.However,the main growth of both above is the collection of cloud water by graupel.It is the freezing rain,the collection of rain by ice and the collection of cloud water and rain by graupel that contributes mostly to the graupel production with Morrison scheme. Deposition is the primary method of graupel growth with this scheme. In Case Two,the graupel production of Lin scheme depends on the accretion of ice to rain, and the main growth is the collection of cloud water and snow by graupel.The results of WSM6 and WDM6 are similar with Case One.But the graupel of Morrison scheme products with the accretion of ice and snow to rain,and grows with deposition,the collection of cloud water and rain process,etc.