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气象:1996,22(9):3-9
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暴雨过程低空急流区域的动能平衡分析
(1.湖南省气象台,长沙 410007;2.中国气象科学院,北京100081)
Energy Transformation in Two Lower Tropospheric Jets Accompaning Storm Rainfalls
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中文摘要: 用有限区域细网格客观分析系统,诊断和分析了 I993年、1994年的两次伴随着 暴雨过程的低空急流选定区域内的动能平衡。发现,虽然计算区域内平均总动能较 大,且有其一定的变化,但计算出的各时次总动能产生值比其变率却一般要大两个量 级以上,表明“波动”间,即“网格(大尺度)-次网格(小尺度)”运动之间的相互作用相 当重要。求两次过程的平均则分别为200、—206W?m-2。表明前次过程平均为动能 源区,具有“大尺度一小尺度(暴雨)”方向转换(耗散)动能的直接环流特征;后次过程 平均为动能汇区,具有“小尺度一大尺度”方向转换(反馈)动能的间接环流特征,即存 在一个所谓“负粘滞”问题。上述两个平均产生值比过去(不涉及暴雨)的分析结果也 要大一个量级。
Abstract:Kinetic energy budgets were prepared for lower tropospheric jet stream accompaning storm rainfalls of two courses in 1993 and 1994,with the use of analyses from a limited-area fine-mesh model (100× 100km2,ten layers) as well as objective analysis system. It shows that the generation rate of kinetic energy (K) by pressure forces is always two-three orders bigger than change rate of K for every time. But the average generation rate as 200—206W/m2 respectively, and the former was a source of kinetic energy (characterized by a large-scale direct solenoidal circulation, the latter was a sink for subgrid-to grid-scale energy transfer,done by a indirect solenoidal circulation. So the kinetic energy changes of the small (subgrid-) scale flow (lead by storm motions) paralleled those of the large-scale flow. This indicates a need for considering the apparent phenomenon of negative viscosity in mesoscale numerical atmospheric modeling for prediction of storm rainfalls.
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辜旭赞,方慈安,吴宝俊,1996.暴雨过程低空急流区域的动能平衡分析[J].气象,22(9):3-9.
,1996.Energy Transformation in Two Lower Tropospheric Jets Accompaning Storm Rainfalls[J].Meteor Mon,22(9):3-9.