共查询到17条相似文献，搜索用时 125 毫秒
1.
多涡自组织的初步研究 总被引：8，自引：5，他引：8
在涡旋自组织动力学的框架内,用f平面二维准地转模式研究了初始场上不规则分布的由12个β和γ中尺度涡构成的涡群如何自组织成一个较大涡旋的问题。结果表明,多涡自组织是一个逐次合并的过程,开始时是相邻双涡的合并,然后形成三涡流型,最后才形成一个α中尺度的终态涡。因此,多涡共存条件下的双涡作用,是多涡自组织的一个基本的物理过程。初始场上的每一个涡或涡块,主要有两类“前景”,一是其涡量与相邻涡涡量合并,成为新的一个涡的内区的涡量来源;二是被相邻涡的环流拉伸,成为新的一个涡的螺旋带涡量的来源。每一个新的涡,类似地也有这两类前景,直至惟一的一个较大尺度的涡自组织起来。初始涡结构描述精度不同,自组织过程中涡互旋和涡合并的速率均会不同,终态涡内区涡量来源也不相同,说明准确给出初始涡群涡结构特征十分重要。最后指出了二维准地转流自组织过程数值解的一个属性,即总动能缓慢衰减,总涡度拟能迅速衰减,最大尺度涡旋的环流迅速加大。 相似文献
2.
小尺度系统对涡旋自组织的影响 总被引：1，自引：1，他引：0
在涡旋自组织动力学的框架内,利用．厂平面准地转正压模式讨论小尺度涡旋系统对两个中β尺度涡旋的自组织过程的影响。4组数值试验表明：小尺度涡旋的存在,可能会改变双涡相互作用的终态,使原本不合并的两个涡旋组织起来;双涡相互作用的终态对小尺度涡旋的初始位置敏感;存在“Z”型敏感区域,当小尺度涡旋出现在这一区域时,就有可能改变双涡相互作用的终态;小尺度涡旋对双涡相互作用产生影响需具备4个条件,即初始位于敏感区内,有足够的强度,距离适当且生存时间足够长。 相似文献
3.
中尺度涡旋和台风涡旋相互作用的数值研究 总被引：8，自引：4，他引：8
用一个高分辨率的正压涡度方程模式，实施了4组积分时间为24h的试验，研究了台风环流区域内中尺度涡旋的不同初始径向位置条件下与台风涡旋的相互作用，结果表明，中尺度涡旋初始径向位置不同，可以引起随后扰动相对涡度场演变特征的改变。 相似文献
4.
涡列涡量内传的数值研究 总被引：1，自引：4，他引：1
用一个高分辨率的准地转正压模式实施了4组积分时间为24h的试验，研究台风环流区域中尺度涡列对台风强度的影响。并与单个中尺度涡旋的情况作了对比。结果表明：涡列内传过程中出现了两次涡合并现象。涡列涡量内传对台风强度的影响能力较弱。单个中尺度涡旋涡量内传可使台风增强。 相似文献
5.
利用高分辨率f平面正压拟谱模式,分析一个β中尺度涡对双台风相互作用影响的物理过程。结果表明：β中涡的存在可以使原本排斥的两个DeMaria型台风涡旋合并;β中涡改变双台风相互作用终态的物理机制是：初始时段处于某一台风涡旋正影响区内的β中涡,构成了非对称涡度场,进而在该台风涡旋内部产生指向另一个台风涡旋的气流。该气流如果足够强,则会使两个台风的中心距离在短时间内下降到合并临界距离之内,触发双涡合并过程的发生。 相似文献
6.
三类物理过程对台风强度影响的研究 总被引：4，自引：2，他引：4
文中设计了一个极坐标系的准地转正压模式 ,一个直角坐标系定常台风环流条件下的准地转正压模式和一个直角坐标系非定常台风环流的准地转正压模式 ,其径向或水平格距均为 2km ,以研究三类物理过程对台风强度的影响 ,即沿方位角方向的线性平流 ,沿径向的线性平流以及非线性平流对中尺度涡旋涡量内传和台风强度变化的影响。结果指出 :沿方位角方向的线性平流可导致螺旋状涡带的形成 ;沿径向的线性平流在一定的参数集合可使涡量内传 ,台风略有增强 ;定常台风环流条件下扰动涡量的非线性平流可使内传涡量明显增加 ,台风明显增强 ;非定常台风环流条件下非线性平流的作用具有两重性 ,一方面可使内传涡量增多 ,有利于台风的增强 ,另一方面 ,在涡量内传过程中 ,原先呈同心圆轴对称的台风基流结构受到破坏 ,形成复杂流型 ,这又使台风趋于减弱。最后讨论了这些结果在台风强度预测方面的可能应用。 相似文献
7.
非轴对称双涡相互作用的研究 总被引：4，自引：3，他引：4
在平流动力学的框架内,用准地转正压涡度方程模式实施了19组试验,研究双涡合并的条件及较大尺度涡旋自组织的问题。结果指出:(1)存在着两个影响双涡合并的因素,即初始双涡中心之间的距离和初始涡旋的非轴对称分布。初始两个对称涡旋合并具有明显的临界距离效应,但初始两个非轴对称涡旋能否合并还受到初始涡旋的非对称结构的复杂影响。(2)存在着两类不同的较大尺度涡旋的自组织过程,形成较大尺度涡旋。第一类,初始两个涡旋相同,均呈轴对称分布。双涡作用经历了缓变、快变,以及涡量羽翼的生成、拉伸和发展的过程,合并后呈对称性流型;终态涡内区涡量的堆积来源于两个初始涡,终态涡外区的螺旋带来源于两个初始涡外缘线涡量羽翼的拉伸。第二类,初始两个涡旋不同,一个为椭圆型,一个为偏心型,均呈非轴对称分布。双涡作用中,椭圆涡一边互旋,一边向计算区域中心靠近,同时涡量范围加大,形成了终态涡的内核区;偏心涡一边互旋,一边被不断拉伸,形成了终态涡的螺旋带区;表现出终态涡内区的涡量堆集来源于椭圆涡,终态涡外区螺旋带主要来源于偏心涡的反复拉伸及断裂的特性。 相似文献
8.
地形对涡旋自组织影响的初步研究 总被引：1，自引：3，他引：1
用一个带有地形项的f平面准地转正压涡度方程，实施5组积分时间长度为72h的试验，研究了中尺度地形对涡旋自组织的影响。结果指出：无地形时，准终态涡是一个带有螺旋带的类似台风的涡旋；有地形时，准终态涡是一个无螺旋带但有两个低涡量区的准圆形涡旋。有无地形两个准终态涡中心的位置可以相距100km以上。 相似文献
9.
台风环流区域内中尺度涡量传播特征的研究 总被引：3，自引：2，他引：3
用一个高分辨率f平面直角坐标系的正压准地转模式,实施了10组积分时间为36 h的试验,研究了初始位于台风外区的一个中尺度涡旋与台风涡旋的相互作用。结果表明:这种相互作用可以激发一个从外区伸展到内区的较小尺度的涡旋对,以此方式将涡量内传至台风中心附近。同时,中尺度涡旋呈现涡量集中化的特征。涡量内传与涡量集中化共存,使内区涡量增多,导致台风增强。此外,在一定条件下,这种相互作用还可以使涡量带破碎和断裂,形成一系列空间尺度更小的涡块。 相似文献
10.
斜压大气中台风涡旋自组织的研究 总被引：2，自引：0，他引：2
文中利用MM5(V3),实施了8个数值试验,对斜压大气中台风涡旋自组织的问题进行了初步研究.结果表明:(1)在试验1中,没有引进一个半径为80 km的小涡旋,两个初始分离的半径为500 km的轴对称涡旋,一边互旋,一边相互排斥,两个涡旋中心之间的距离不断加大,致使双涡最终分离.(2)在试验2中引进了一个半径为80 km的小涡旋,其他条件同试验1,两个初始分离的轴对称涡旋一边互旋,一边相互逼近,经自组织形成了一个由内区和螺旋带组成的类似于台风环流的较大尺度的涡旋.这个结果支持周秀骥在十多年前提出的重要观点,也支持以往在正压框架内的同类研究结果.(3)试验3-8为在前两个试验的基础上取不同初始涡旋参数的敏感性试验,其中,试验3和4为引入小涡旋不同初始位置对台风涡旋自组织的影响,试验5和6为不同初始轴对称双涡间距对台风涡旋自组织的影响,试验7和8反映了不同初始轴对称双涡强度对台风涡旋自组织的作用.它表明对涡旋自组织过程影响最大的涡旋初始参数是涡旋之间的距离,其与正压模式中的结果是类似的. 相似文献
11.
Previous studies concerning the interaction of dual vortices have been made generally in the deterministic framework. In this paper, by using an advection equation model, eight numerical experiments whose integration times are 30 h are performed in order to analyze the interaction of dual vortices and the vortex self-organization in a coexisting system of deterministic and stochastic components. The stochastic components are introduced into the model by the way that the Iwayama scheme is used to produce the randomly distributed small-scale vortices which are then added into the initial field. The different intensity of the small-scale vortices is described by parameter K being 0.0, 0.4, 0.6, 0.8, and 1.0, respectively. When there is no small-scale vortex （K=0.0）, two initially separated meso-beta vortices rotate counterclockwise mutually, and their quasi-final flow pattern is still two separated vortices; after initially incorporating small-scale vortices （K=0.8, 1.0）, the two separated meso-beta vortices of initially same intensity gradually evolve into a major and a secondary vortex in time integration. The major vortex pulls the secondary one, which gradually evolves into the spiral band of the major vortex. The quasi-final flow pattern is a self-organized vortex with typhoon-like circulation, and the relative vorticity at its center increases with increasing in K value, suggesting that small-scale vortices feed the self-organized vortex with vorticity. This may be a possible mechanism responsible for changes in the strength of the self-organized vortex. Results also show that the quasi-final pattern not only relates with the initial intensity of the small-scale vortices, but also with their initial distribution. In addition, three experiments are also performed in the case of various boundary conditions. Firstly, the periodic condition is used on the E-W boundary, but the fixed condition on the S-N boundary; secondly, the fixed condition is set on all the boundaries; and thirdly, the periodic conditio 相似文献
12.
An Investigation into Effect of Randomly Distributed Small Scale Vortices on Vortex Self-Organization 
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下载免费PDF全文 Previous studies concerning the interaction of dual vortices have been made generally in the determin-istic framework. In this paper, by using an advection equation model, eight numerical experiments whose integration times are 30 h are performed in order to analyze the interaction of dual vortices and the vortex self-organization in a coexisting system of deterministic and stochastic components. The stochastic compo-nents are introduced into the model by the way that the Iwayama scheme is used to produce the randomly distributed small-scale vortices which are then added into the initial field. The different intensity of the small-scale vortices is described by parameter K being 0.0, 0.4, 0.6, 0.8, and 1.0, respectively. When there is no small-scale vortex (K=0.0), two initially separated meso-beta vortices rotate counterclockwise mutu-ally, and their quasi-final flow pattern is still two separated vortices; after initially incorporating small-scale vortices (K=0.8, 1.0), the two separated meso-beta vortices of initially same intensity gradually evolve into a major and a secondary vortex in time integration. The major vortex pulls the secondary one, which gradually evolves into the spiral band of the major vortex. The quasi-final flow pattern is a self-organized vortex with typhoon-like circulation, and the relative vorticity at its center increases with increasing in K value, suggesting that small-scale vortices feed the self-organized vortex with vorticity. This may be a pos-sible mechanism responsible for changes in the strength of the self-organized vortex. Results also show that the quasi-final pattern not only relates with the initial intensity of the small-scale vortices, but also with their initial distribution. In addition, three experiments are also performed in the case of various boundary conditions. Firstly, the periodic condition is used on the E-W boundary, but the fixed condition on the S-N boundary; secondly, the fixed condition is set on all the boundaries; and thirdly, the periodic condition is chosen on all the boundaries. Their quasi-final flow patterns in the three experiments are the same with each other, exhibiting a larger scale typhoon-like circulation. Based on these results mentioned above, authors think that the transition of vortex self-organization study from the deterministic system to the coexisting system of deterministic and stochastic components is worth exploring. 相似文献
13.
Self-organization of typhoon vortex in a baroclinic environment is studied based on eight numerical experiments with the fifth-generation Pennsylvania State University/National Center for Atmospheric Research （PSU/NCAR） Mesoscale Model （MM5）. The results show that, when there are only two 400-km-away mesoscale axisymmetric vortices with a radius of 500 km in the initial field, the two vortices move away from each other during co-rotating till the distance between them greater than a critical distance named co-rotating critical distance. Then, they stop co-rotating. The situation is changed when a small vortex with a radius of 80 kin is introduced in between the two vortices in the initial field, with the two initially separated vortices approaching each other during their co-rotation, and finally self-organizing into a typhoon-like vortex consisting of an inner core and spiral bands. This result supports both Zhou Xiuji＇s view in 1994 and the studies in the barotropic framework concerning the interactions between the same and different scales of vortices. Six other experiments are carried out to study the effects of the initial vortex parameters, including the initial position of the small-scale vortex, the distance and intensity of the initially axisymmetric binary mesoscale vortices. It is found that the distance between the initial axisymmetrie mesoscale vortices is the most important parameter that influences the self-organizing process of the final typhoon-like vortex. This conclusion is similar to that obtained from barotropical model experiments. 相似文献
14.
用一个高分辨率的 f平面正压涡度方程模式 ,实施了时间积分为 36h的 2 1组试验 ,研究相邻中尺度涡旋与台风涡旋的相互作用。结果指出 :这种相互作用能否导致台风加强 ,取决于两类因子 :一是台风涡旋最大风速的取值以及圆形基流切变的强弱 ;二是切变基流中的中尺度涡旋的自身条件 ,包括中尺度涡旋的分布、尺度、强度和结构。台风强度与初始中尺度涡旋的尺度、强度之间存在着非线性的联系 相似文献
15.
Eight sets of numerical experiments are performed in 48 hours of integtation by using a barotropic primitive equation model with a topographic term so as to investigate the effect of topography on the merging of vortices. It is pointed out that the introduction of topography may change the track of vortices,and it causes the low vortices and vorticity lumps to be detained on the southeast side of the topography,thus creating a favorable condition for the merging of the low vortex and vorticity lumps. It is also shown that the effect of topography may cause double mergers of vortices in a horizontally shearing basic flow,and it can strengthen the low vortex remarkably. 相似文献
16.
A numerical study of multiple vortex self-organization as forced by mesoscale topography 总被引：1，自引：0，他引：1
Summary There exists a common observational phenomenon over the offshore areas of the northwest Pacific, that is, when several mesoscale
vortices evolve suddenly into a larger scale typhoon-like vortex within one day, often with serious consequences. In this
paper a series of numerical experiments has been designed and performed to emulate this evolution. The model is based on the
Charney-Hasegawa-Mima equation, where there are around 40 initial meso-β vortices with parabolic profiles whose central positions,
dimensions and intensities are all set stochastically. The self-organization process of these stochastically-distributed multiple
meso-β vortices can be divided into two phases. During the first phase, a larger scale vortex similar to a typhoon-like vortex
forms near the computational center through the gradual stretching and merging of adjacent meso-β vortices while there are
more than 10 isolated vortices surrounding this typhoon-vortex. During the second phase, the isolated vortices are stretched
and drawn into the typhoon-vortex circulation and become its spiral arms which are gradually incorporated into the inner area
of the typhoon. This is then repeated as new isolated vortices are stretched and become new spiral arms until all the isolated
vortices are drawn into the typhoon-vortex. The center of the self-organized typhoon-vortex rotates counterclockwise around
the computational center when no topography is involved and is thus a transient vortex. When topography is present the vortex
remain in the NE quadrant of the model domain, locked by the topography, and this quasi-steady vortex is thus capable of causing
local disasters.
Correspondence: Chongjian Liu, Chinese Academy of Meteorological Sciences (CAMS), State Key Labaratory of Severe Weather,
46 Zhongguancum South Avenue, 100081 Beijing, P.R. China 相似文献
17.
LUO Zhexian 《Acta Meteorologica Sinica》2004,18(2):179-194
By using an f-plane barotropic quasi geostrophic model in the rectangular coordinates with a grid spacing of 5 km,ten experiments whose integration time is 36 hours are performed in order to study the interaction between a typhoon vortex and a mesoscale vortex whose initial center position is located at 2 rm northwest to the typhoon center,where rm is the radius of maximum wind of the typhoon vortex. Results show that the interaction can create a pair of smaller scale vortices or lumps,which extend from the outside region of the typhoon to near its center,resulting in the inward propagation of mesoscale vorticity.In this process,the vorticity concentration of the mesoscale vortex may appear.The coexistence of the propagation and the concentration makes the increase of vorticity in the inside region i.e.a more intensive typhoon.Meanwhile,the intensity of the lump with positive vorticity oscillates with time,with the oscillation period being several hours,the distance from the typhoon center to the lump center also has a similar oscillation period,which reduces the oscillation of typhoon intensity.In the case of stronger circular basic flow,the interaction can make the intensification of typhoon more obviously. In addition,in some parametric conditions,the interaction may break down the continuous vorticity zone,exhibiting a cluster of smaller vorticity lumps. 相似文献