双参数微物理方案的冰相过程模拟及冰核数浓度的影响试验1  

Numerical Simulation of Ice-Phase Processes Using a Double-Moment Microphysical Scheme and a Sensitivity Test of Ice Nuclei Concentration

作　　者：沈新勇[1,2] 梅海霞[1,3] 王卫国 黄文彦[1] 

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室,南京210044 [2]中国科学院大气物理研究所云降水物理与强风暴实验室,北京100029 [3]江苏省气象科学研究所,南京210009 [4]美国国家海洋大气管理局环境预测中心,马里兰20746

出　　处：《大气科学》2015年第1期83-99,共17页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划(973计划)项目2013CB430103;2015CB453200;国家自然科学基金项目41375058;41175065;江苏高等学校优秀科技创新团队计划项目PIT2012

摘　　要：利用耦合Morrison 2-mon(MOR)双参数微物理方案的中尺度天气研究与预报模式(WRF)中的单气柱模式,对热带暖池国际云试验(TWP-ICE)期间的个例进行数值模拟。通过与观测资料和云分辨率模式的模拟结果进行对比,检验MOR方案对热带对流云系的微物理特征的模拟能力。模拟结果显示:MOR方案能够较好地模拟出热带云系中液相和冰相水凝物的垂直分布以及随时间的演变特征。地表向下长波辐射和大气顶向外长波辐射的量级和时间演变趋势同观测也非常接近。对与冰晶和雪有关的云微物理特征分析之后发现:季风活跃期,冰晶主要的源汇项有凝华增长过程、沉降过程、冰晶向雪的自动转化以及冰晶被雪碰并的过程。由于冰晶主体位于温度低于―20°C的高空,因而它对雨水的形成主要是间接贡献。同时期雪的主要源汇项中,凝华增长和沉降过程占据着主导地位。雪的凝华过程消耗了大量的水汽,可能抑制了冰晶的增长。另外雪的融化过程非常强盛,是产生降水的重要因子。季风抑制期,冰相的微物理过程变得相对简单且整体削弱,以凝华升华和沉降过程为主。凝华凝冻核的数浓度(Ndep)的气溶胶敏感性试验表明:季风抑制期,高空的冰晶云的宏观和微观性质对凝华凝冻核数浓度的响应情况呈现显著的线性特征。冰晶的含量随着Ndep的增加而增加,反之降低。该时期微物理过程主要同冰晶有关,水分的分配较为简单,Ndep增加时,高空冰云中小冰晶粒子数目增多且云顶升高,使得大气顶部向外长波辐射(OLR)值减小,反之冰云主体中冰晶有效半径增加,高空的冰云更加透明,云顶更低,对OLR值增加起促进作用。而季风活跃期,微物理过程复杂,冰晶云的宏微观特征对Ndep的响应表现出一定的不规律特征。In the context of the Weather Research and Forecasting （WRF） single column model （SCM）,a double-moment bulk microphysics scheme,Morrison 2-mon （MOR）,is selected to simulate a case of tropical convection from the Tropical Warm Pool International Cloud Experiment （TWP-ICE） field experiment.We then compare the results with observations and cloud resolution model results to evaluate the ability of the MOR scheme to describe the microphysics.The evidence shows that the MOR scheme is capable of properly reproducing the time and space distribution features of liquid and ice particles in the tropical cloud from both macro and micro points,as well as the characteristics of the temporal evolution of surface downward longwave radiation and outgoing longwave radiation （OLR） at the top of atmosphere.From our analysis of microphysical characteristics,we found that the dominant ice crystals cloud microphysical processes during the monsoon active period are the depositional growth of ice crystals,sedimentation of ice crystals,autoconversion of ice crystals to snow,and accretion of ice crystals by snow.Ice crystals occur predominantly in environmental temperatures less than-20°C,and indirectly contribute to rain formation.The cloud microphysical processes of snow are predominantly its simultaneous sedimentation and depositional growth.Snow＇s strong deposition growth,which results in the consumption of much water vapor,may suppress ice crystal growth.In addition,the active melting of snow is an important factor for precipitation.During the monsoon depression,ice-phase microphysics become relatively simple and weaken,with the dominant cloud microphysical processes being sublimation,sedimentation,and depositional growth.Results from MOR scheme sensitivity tests,in which we changed the total number of ice nuclei in deposition mode and condensation freezing mode （Ndep）,suggested that the responses of the macro and micro characteristics in ice-phase cloud to Ndep present marked linear features during the mons

关 键 词：单气柱模式 MORRISON 2-mon方案 微物理 凝华凝冻核 TWP-ICE试验 

分 类 号：P457[天文地球—大气科学及气象学]