可造成持续性强降水的高原低涡群发效应与大气10-30天低频振荡的联系PPT课件

1、Clustering of Tibetan Plateau Vortices by 10-30-day ISO可造成持续性强降水的高原低涡群发效应与大气1030天低频振荡的联系1. Introduction 1.1 Tibetan Plateau Vortex (TPV)Characteristics: Sub-synoptic or meso-scale convective systems at 500hPa; horizontal scale of several hundred kilometers; (Gao et al. 1981; Tao and Ding 1981)Contri

2、buting factors: topography, low-level convergence, surface sensible heating, latent heat release, etc. (e.g., DellOsso and Chen 1986; Gao 2000; Li et al. 2002; Shen et al. 1986; Shi et al. 2008; Sugimoto and Ueno 2010; Wang 1987)Tibetan Plateau Vortex (TPV) Influences: 青藏高原独特的地理环境造就的高原特色天气系统。TPV的活动不

3、仅影响高原地区，还东移影响我国高原下游广大地区。夏季：暴雨洪涝,泥石流、滑坡；冬季：暴雪，雨雪冰冻。 The primary factors for local (TP) precipitation (e.g., TP Meteor. Workshop 1981);Extreme rainfall events in the East Asia (e.g., Rui et al. 1987; Tao and Ding 1981; Wang and Orlanski 1987; Wang et al. 2005);For example, the heavy rainfall and sever

4、e flooding in 1998 over the Yangtze-River basin (Shi et al. 2008; Yasunari and Miwa 2006; Yu 2001).高原涡与西南涡的区别（TPV VS SWV）高原类低涡低涡名称高原涡（广义）西南涡高原东坡涡（狭义）西南涡水平尺度直径（km）-中尺度，300500-中尺度，300500-中尺度，300500生命史和活跃期3d，68月2d，57月3000100030001000定涡标准500 hPa等压面上，高原地区形成闭合等高线的低压或有3个站点风向呈气旋性的低涡环流700hPa等压面上，青藏高原东麓背风坡特定地

5、区（100110E，2535N）出现的闭合气旋式低涡环流移出比25%左右移出高原（东移过102E）20%左右移出源地TPV的天气影响高原涡天气影响的常态：中尺度，生命史一般3天，区域性短期暴雨，对流性短时天气高原涡对持续性暴雨的作用（异常影响）（1）影响方式：1）长生命史或持续性活动（停滞：西太副高、台风）的TPV（不多见）2）高原涡与西南涡（SWV）耦合加强3）TPV的群发效应（2）影响机理：延时、增幅、扩面TPV对1998长江持续性暴雨的作用（补充天气图、卫星云图展示的高原涡东移过程？）1998年，长江流域发生自1954年以来的最大洪水，宜昌出现八次大洪峰，其中有一半以上与高原低涡、切变线

6、东移密切相关，即长江上游暴雨、高原天气系统与四川云团的活动对 年长江洪峰的形成有直接影响（TPV的“五峰暴雨”，郁淑华，2000）。对形成1998年长江上游八次洪峰的有关强降雨天气过程的影响天气系统分析表明：生成在青藏高原东部在四川盆地发展的低涡及与其相连的切变线是1998暴雨产生的主要天气系统;暴雨的加强与中低纬度系统相互作用、高原涡的特殊结构密切相关（杨克明、毕宝贵等，2001）。1998年长江上游暴雨偏多与该年夏季西南低涡活动偏多有关（陈忠明等，2003）1.2 Clustering of TP vorticesTPVs Exhibit apparently active and sup

7、pressed periods (Luo et al. 1994) TPVs continuously generate within several days Clustering (Sun and Chen 1994)Previous studies:Clustering is primarily modulated by the 30-60-day intraseasonal oscillation (ISO) over the TP (Sun and Chen 1994; Zhang et al. 1991)Submonthly (10-30-day or 10-20-day) ISO

8、Submonthly Intraseanal oscillation (ISO) can also modulate convective activities over the TP (Fujinami and Yasunari 2004; Yasunari and Miwa 2006) Our result show that: TPV better matches the 10-30-day oscillation than the 30-60-day one in 1998! 1.3 Data and methodData:Station observation: Twice-dail

9、y (00, 12)GMS-5 TBB: Daily meanCFSR, ERA, NCEP1: Daily meanTime: May - Sep in 1998Method: Bandpass filterComposite Ensemble 2. Tibetan Plateau Vortices activity in 1998 SummerFig.1 Daily occurrence numbers (bar chart) and the clustering periods (gray shaded) from twice-daily synoptic mapsTP vortex d

10、efinition: A closed low pressure on 500-hPa (lower troposphere over TP) synoptic weather maps or a cyclonic circulation observed by at least 3 meteorological stations (青藏高原气象科学研究拉萨会战组，1981)Clustering periods: Persist for at least three continuous days;vortices number in a given period is at least fo

11、ur; Temporal interval between two vortices should not be greater than 1 day.(Sun and chen 1994)80% of total vortices occurring in clustering periods青藏高原低涡群发期的定义：(1)低涡群发期不少于三天；(2)低涡出现次数不少于5个频次；(3)两次低涡过程间隔期不超过一天。1998年夏季高原低涡的9个群发期3. Relationship between ISOs and clustering periods 月份低涡群发期5812日6210日；253

12、0日7410日；2124日815日；1114日；1719日；2629日Large-scale background circulation at 500hPaFig.2 Locations of TP vortices (C) ; shaded is composite GMS-5 TBB (Unit: K); 2500m of topography (dashed line).May-August averageComposite stream line in clustering periodsConvergent and convective regionFig.3 Nine clust

13、ering periods (gray shaded) and the ensemble time series of ISOs of 500-hPa relative vorticity (10-5 s-1); standard error (blue shaded) of CFSR, ERA-40 and NCEP. Regional average of (29-36N, 85-100E) TPV的9个群发期 VS ISO所有9个群发期均对应10-30-day ISO 的正位相期；其中6个对应30-60-day ISO的正位相期Temporal evolution of 10-30-da

14、y ISO10-30-day in relative vorticity (shaded is positive)TP vortices C. Zonal (ave 29-36N) Meridional (ave 85-100E) clustering periods4. Mechanism linking 10-30-day ISO and clustering of TP Vortices Phase composite 1st phase2nd (positive) phase300hPa500hPa8 TP Vortices in Phase 1 (18%)29 in Phase 2

15、(64%)High CAPEHorizontal Wind (vector in upper and lower, m/s)Equivalent potential temperature (Theta-se, red contour, K)Vertical velocity (Omega, blue-green shaded, Pa s-1)Divergence of moisture flux (blue-red shaded, 10-5 g hPa-1 cm-2 s-1)Gray shaded in middle and contour in upper and lower are Ti

16、betan Plateau.CAPE realseTPV群发与10-30d ISO的物理联系the large-scale convergence of moisture advection through the southwest of TP connecting to the Indian monsoon activity lead to the high moist static energy accumulation at the lower troposphere over TP. The low-level convergence excites deep convective

17、systems over the central-eastern TP. The latent heat release of the deep convection can enhance the upward motion through convection-circulation feedback. The moisture supply through the southeast(SE LLJ) of TP further ensures the persistence of convective disturbances.3rd phase4th (negative) phase3

18、00hPa500hPaHorizontal Wind (vector in upper and lower, m/s)Equivalent potential temperature (Theta-se, red contour, K)Vertical velocity (Omega, blue-green shaded, Pa s-1)Divergence of moisture flux (blue-red shaded, 10-5 g hPa-1 cm-2 s-1)Gray shaded in middle and contour in upper and lower are Tibet

19、an Plateau.6 TP Vortices in Phase 3 (13%)2 in Phase 4 (4%)5. Concluding remarksOccurrences of TPV exhibit obvious active and quiescent periods. Nine clustering periods in 1998 summerNine Clustering periods (3-6day，related to persistent heavy rain)80% TPVs are occurring in those periods All (6) clust

20、ering periods are occurring in active phases of 10-30-day (30-60-day)ISO.In 10-30-day scale, high moist static energy accumulation at the lower troposphere over TP by southerly.Latent heat release of the deep convection in TP vortices systems can enhance the upward motion through convection-circulat

21、ion feedback.10-30天季节内振荡对高原低涡群发性的调制作用利用每天2次500hPa天气图、多种再分析资料和卫星反演的亮温资料，研究了1998年5-9月青藏高原低涡与10-30天季节内振荡的关系。研究揭示出活跃期与非活跃期的高原低涡存在显著差异。 1998年高原低涡有9个活跃期，高原低涡的群发与气旋式环流联系的500hPa涡度场的季节内振荡有关。夏季高原低涡的群发现象明显受10-30天振荡的调制，所有高原低涡的活跃期都位于10-30天振荡的正位相。该结果显现出10-30天振荡通过提供有利于（不利于）气旋式（反气旋式）环境流场直接调制着高原低涡的活动；大气低频振荡分析表明：10-3

22、0天尺度上，在来自印度季风区低层暖对流引起的对流不稳定配合下，西风槽扰动可激发高原低涡活动。来自高原西南边界的水汽输送是对流能量汇聚的一个重要影响因子。本研究结果使我们认识到10-30天季节内振荡的预测将有助于提升高原低涡及其影响高原下游地区天气、气候的中期预报能力。已发表4篇SCI文章：Pengfei Zhang, Guoping Li, Xiouhua Fu, Yimin Liu, Laifang Li. Clustering of Tibetan Plateau vortices by 10-30-day intraseasonal oscillation,Monthly Weather

23、 Review, 2014,142(1):290-300(SCI收录号：282UX）Chen Gong , Li Guoping* . Dynamic and numerical study of waves in the Tibetan Plateau vortex, Advances in Atmospheric Sciences, 2014, 31(1):131-138（SCI收录号：277NY）Jiaona Chen, Guoping Li *. Diurnal variation of ground-based GPS-PWV under different solar radiat

24、ion intensity in Chengdu Plain, Journal of Geodynamics, 2013, 72(SI）:81-85. (SCI收录号：286PZ）Guoping Li, Jia Deng. Atmospheric water monitoring by using ground-based GPS during heavy rains produced by TPV and SWV, Advances in Meteorology, 2013, 1-12(SCI收录号：276QU） 2013.-2014.4 项目第一署名研究成果根据课题组分工主攻持续性天气异常

25、的2个研究方向：（1）高原与行星波 （2）TPV and SWV已发表核心期刊文章5篇，一般期刊文章2篇何钰，李国平*. 青藏高原大地形对华南持续性暴雨影响的数值试验，大气科学，2013，37(4): 933-944李国平，赵福虎，黄楚惠，牛金龙. 基于NCEP资料的近30年夏季青藏高原低涡的气候特征. 大气科学,2014, 38(4)胡祖恒，李国平*，官昌贵，王红丽. 中尺度对流系统影响西南低涡持续性暴雨的诊断分析，高原气象，2014，33（1）：116-129蒋璐君， 李国平*，母灵，孔亮. 基于TRMM资料的西南涡强降水结构分析，高原气象，2014，33（3）倪成诚,李国平*,熊效振. AIRS资料在中国川藏地区适用性的验证研究，2013，31（6）：656-663山地学报李国平.高原涡、西南涡研究的新进展及有关科学问题，沙漠与绿洲气象,2013，7（3）：1-6母灵，李国平.复杂地形对西南低涡生成和移动影响的数值试验分析，成都信息工程学院学报，2013，28（6）：241-248 目前的研究（SCI录用1篇，核心期刊录用2篇，SCI修改2篇，SCI待投稿2篇）蒋璐君，李国平，王兴涛.基于TRMM资料的高原涡与西南涡引发强降水的对比研究，大气科学（录用）