积云参数化方案中云底质量通量的限制及在高分辨率模式中的应用  

THE LIMITATION OF CLOUD BASE MASS FLUX IN CUMULUS PARAMETERIZATION AND ITS APPLICATION IN A HIGH-RESOLUTION MODEL

作　　者：徐道生[1,2] 陈子通[1,2] 钟水新[1,2] 温焰军 谢东东[3] 

机构地区：[1]中国气象局广州热带海洋气象研究所 [2]中国气象局广东省区域数值天气预报重点实验室 [3]中国人民解放军95915部队气象台

出　　处：《热带气象学报》2014年第3期401-412,共12页Journal of Tropical Meteorology

基　　金：华南区域气象中心科技攻关项目(GRMC2014M04);公益性行业(气象)科研专项(GYHY201206010)"热带环流系统的数值天气预报技术研究";课题资助项目:广东省科技计划项目(2011A032100006)"广东省突发灾害性天气应急技术研究中心";广东省科技计划项目2012A061400012;对流尺度集合预报技术与业务应用(2013A04);2013年气象关键技术集成与应用项目(华南区域高分辨率0~12小时数值模式预报技术研究与系统集成:CMAGJ2013M34)共同资助

摘　　要：对SAS积云参数化方案中的云底质量通量进行限制并将其应用到华南区域高分辨率模式降水预报中,分别对强对流个例和弱对流个例进行模拟和比较,分析了限制云底质量通量之后的积云参数化方案对模式降水预报的影响,并探讨了不同大小的云底质量通量限制对预报结果的敏感性。试验结果表明,对积云参数化方案进行闭合时采用不稳定能量释放假设要比原来的准平衡闭合假设更适用于中小尺度模式。对积云参数化方案的云底质量通量进行限制以后可以有效地消除对流参数化在高分辨率模式中引起的虚假降水,同时又能够合理地引入一些次网格尺度的弱对流的影响,从而改进模式的降水预报效果。敏感性试验结果表明,随着云底质量通量限制程度的变弱,对流参数化方案对模式降水预报的影响会逐渐增强;在一定大小范围内的云底质量通量限制下,强对流个例的总降水量预报结果对于不同大小的限制不如弱对流个例敏感。对两种不同的云底质量通量限制方式进行比较发现,在云底质量通量较大时完全关闭对流参数化方案可以更有效避免对流参数化引起的虚假降水。A large area of unrealized precipitation is produced with the standard convective parameterization scheme in a high-resolution model, while subgrid-scale convection that cannot be explicitly resolved is omitted without convective parameterization. A modified version of the convection scheme with limited mass flux at cloud base is introduced into a south-China regional high-resolution model to alleviate these problems. A strong convection case and a weak convection case are selected to analyze the influence of limited cloud base mass flux on precipitation forecast. The sensitivity of different limitation on mass flux at cloud base is also discussed. It is found that using instability energy closure for SAS scheme will produce better precipitation forecast than the primary closure based on quasi-equilibrium assumption. The influence of the convection scheme is dependent on the upper limit of mass flux at cloud base. The total rain amount is not so sensitive to the limitation of mass flux in the strong convection case as in the weak one. From the comparison of two different methods for limiting the cloud-base mass flux, it is found that shutting down the cumulus parameterization scheme completely when the cloud-base mass flux exceeds the given limitation is more suitable for the forecast of precipitation.

关 键 词：积云参数化 高分辨率模式 云底质量通量 

分 类 号：P456.7[天文地球—大气科学及气象学]