| 2003年淮河大水期间亚洲北部阻塞高压的形成特征 |
| |
| 引用本文： | 李峰,丁一汇,鲍媛媛.2003年淮河大水期间亚洲北部阻塞高压的形成特征[J].大气科学,2008,32(3):469-480. |
| |
| 作者姓名： | 李峰 丁一汇 鲍媛媛 |
| |
| 作者单位： | 1.国家气象中心, 北京, 100081 |
| |
| 摘 要： | 利用观测资料和NCEP再分析资料分析2003年淮河大水期间亚洲北部阻塞高压的形成维持机制, 结果表明, 2003年淮河梅汛期亚洲中高纬地区阻塞高压的异常活动中, 波流作用十分显著。6月上旬, 阻高建立前期和维持过程中, 上游地区天气尺度波动活跃, 欧洲斜压区不断有瞬变动能生成, 并在阻塞区向阻高平均流转化。从瞬变涡动的作用来看, 上游传播而来的瞬变波不断将较低纬度的低位涡空气向阻塞区输送, 有利于阻塞高压的建立维持; 平均流则使位涡呈相反形势发展, 引导阻塞高压向东频散, 削弱了扰动位涡输送的作用, 对阻高的维持起到耗散作用。阻高建立前, 瞬变涡位涡输送作用强于平均流位涡平流, 造成阻塞区位涡降低, 有利于阻高生成; 阻高维持期间, 瞬变涡位涡输送与平均流位涡平流输送量相当; 6月25～30日, 阻塞高压明显西退, 该阶段瞬变涡动明显强于平均耗散作用, 引导低位涡场向西移动。研究表明, 大气内部的波波作用对阻高的建立维持也十分重要。1波与5波在一定范围内的共同作用可能是阻高建立维持的决定因素, 而天气尺度波动扰动则对阻塞高压的建立、 维持和崩溃起到重要的作用。波波作用表明, 2003年6月份阻塞高压建立、 维持时, 尺度较长的波一般从平均动能得到扰动动能的转化, 尤其5波, 斜压能的转换不但是其能量的来源, 同时非线性作用也使得尺度更小或更长的波向其提供能量; 阻高衰退时, 5波则通过非线性作用向其他波动输送能量, 同时也存在斜压耗散, 能量逐渐失去。
|
| 关 键 词： | 淮河大水 阻塞高压 形成机制 |
| 文章编号： | 1006-9895(2008)03-0469-12 |
| 修稿时间： | 2006年11月14 |
A Study of the Forming Characteristics of Blocking High in Northern Asia during the Flood Period of the Huaihe River Basin in 2003 |
| |
| LI Feng,DING Yi-Hui and BAO Yuan-Yuan.A Study of the Forming Characteristics of Blocking High in Northern Asia during the Flood Period of the Huaihe River Basin in 2003[J].Chinese Journal of Atmospheric Sciences,2008,32(3):469-480. |
| |
| Authors: | LI Feng DING Yi-Hui and BAO Yuan-Yuan |
| |
| Abstract: | Summer blocking anticyclones are studied to probe into their activity mechanism by using NCEP daily reanalysis dataset and observation data during the flood period of the Huaihe River basin in 2003.The energy and dynamical diagnosis along with some statistic methods such as spectrum decompose,filter are widely used to investigate this subject.Especially,spectrum energy equation is introduced into this work.The results show that interaction of wave and flow is remarkable for the establishment and maintenance of the northern Asia blocking high during 2003 Meiyu period.Synoptic-scale waves are active over the upriver region,transient eddy kinetic energy is generated ceaselessly in European baroclinic zone,and it transforms into blocking mean flow energy in some preferred area in earlier June in more detail,transient eddy transport low potential vorticity(PV) air from low latitudes to blocking area continuously,which is propitious to blocking event.By contraries,mean flow weakens disturbed eddy PV function,which dissipates the blocking stream foundation and maintenance.In fact transient eddy is stronger than mean flow in the prophase that the blocking high forms according to study.The two are equivalent during the maintenance of the blocking high,and the transient eddy gets stronger than mean flow and it shifts westward,which leads low PV to evolve westward,thus the blocking body moves westward in the sixth pentad of June.Properly,wave-wave interaction is also important for the blocking high activity.It is considered as a key factor of the establishment and maintenance of the blocking high during 2003 Mei-yu period that wavenumber-1 and wavenumber-5 interacted in some area according to this research.Synchronously,synoptic-scale waves were also crucial.The interaction among the waves indicates that the longer waves got disturbance kinetic energy from mean kinetic energy transformation when blocking anticyclone began to establish and maintain in June 2003,especially,wavenumber-5 may attained energy not only by baroclinic energy transform,but also by nonlinear effect that some shorter or longer waves provided energy for it.The process is very complex and it is reverse while the blocking high trends to decay. In conclusion,the blocking activities mechanism is complicated,which includes wave-wave interaction ane wave-flow interaction,in 2003,wavenumber-5 and wavenumber-1 interacted evidently,the synoptic-scale wave worked as a trigger,but it is not aptotic,perhaps other wavenumbers are more important in other cases,further work will be continued. |
| |
| Keywords: | the Huaihe River basin flood blocking high activity mechanism |
| 本文献已被 CNKI 维普 万方数据 等数据库收录！ |
| 点击此处可从《大气科学》浏览原始摘要信息 |
| 点击此处可从《大气科学》下载免费的PDF全文 |
|
