doi:  10.3878/j.issn.1006-9895.1806.18135
基于变分客观分析方法的青藏高原试验区夏季对流降水过程热动力特征分析

The Analysis on Thermodynamic Characteristics of Summer Convective Precipitation in Qinghai-Tibet Plateau Experimental Region Based on Constrained Objective Variational Analysis
摘要点击 438  全文点击 89  投稿时间:2018-03-09  修订日期:2018-05-17
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基金:  国家自然科学基金
中文关键词:  青藏高原  变分客观分析  夏季对流降水  热力特征
英文关键词:  Qinghai-Tibet Plateau  constrained objective analysis  convection precipitation
     
作者中文名作者英文名单位
庞紫豪pangzihao中国气象科学研究院灾害天气国家重点实验室;
王东海wangdonghai中山大学大气科学学院;
引用:庞紫豪,王东海.2018.基于变分客观分析方法的青藏高原试验区夏季对流降水过程热动力特征分析[J].大气科学
Citation:pangzihao,wangdonghai.2018.The Analysis on Thermodynamic Characteristics of Summer Convective Precipitation in Qinghai-Tibet Plateau Experimental Region Based on Constrained Objective Variational Analysis[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文利用基于变分客观分析方法的物理协调大气分析模型,构建了青藏高原试验区大气热力-动力相互协调的数据集,并通过该数据集对青藏高原试验区夏季深厚及浅薄对流降水过程的热动力特征进行分析,结果表明:变分客观分析后的垂直速度场能更好地与实际观测的对流降水过程相吻合;深厚对流降水期高云含量多,整层大气为较强的上升运动,上升运动可达100hPa左右,浅薄期高云含量少,上升运动仅能延伸到300hPa左右;两种对流降水过程中视热源Q1在低层为冷却作用,高层为加热作用,在深厚期中高层Q1存在两个加热中心,中层受较强的水汽凝结释放潜热加热所影响,高层主要受过冷云水凝结成冰晶形成高云时释放的热量所影响;在浅薄期中高层Q1只存在一个加热中心,大气的加热主要来源于水汽的凝结潜热释放;深厚对流降水期视水汽汇Q2的加热作用可以延伸到200hPa,而浅薄期仅到340hPa左右。
Abstract:
      Using flux data on the top and the bottom of a column to keep the column’s mass, moisture and static energy constraint, thermal and dynamic coordinated datasets are generated with the analysis model based on constrained objective analysis approach of Zhang and Lin [1997]. By using this dataset, we can analyze thermal characteristics of precipitation process in summer deep convection system and shallow convection system. Vertical velocity is an important indicator of convection strength. The vertical velocity field obtained from constrained objective analysis can better match the observed convective precipitation process compared to ERA-Interim reanalysis data.In the deep convective precipitation period, there is more high cloud content, and the whole atmosphere is a strong ascending movement. The ascending movement can reach about 100 hPa. In the shallow period, the high cloud content is small, and the ascending motion can only extend to around 300 hPa. For both types of precipitation process, Q1 shows the cooling effect on the lower level as the heating effect on the upper level. The possible reason is that the evaporation in the near-surface layer absorbs a large amount of heat which causes the heat in the lower atmosphere to decrease. During the deep convection period, the medium and high level Q1 showed a bimodal structure, the middle layer was affected by latent heat release from the strong condensation of water vapor and the upper layer was mainly affected by the latent heat released when the super-cooled water was condensed into ice crystals to form high-level cloud. In the shallow precipitation period, the medium and high level Q1 showed a unimodal structure in accord with Q2, and the atmospheric heating mainly comes from the latent heat of condensation of water vapor. For deep convection system precipitation period, Q2 can extend to 200hPa depending on the effect of latent heat release from water vapor, while the Q2 of shallow convection precipitation period only extend about 340hPa.
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