Geophysical and Astrophysical Fluid Dynamics最新文献_第9页

Coalescence of lenticular anticyclones in a linearly stratified rotating fluid 透镜状反气旋在线性分层旋转流体中的聚合

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-03-18 DOI: 10.1080/03091929.2020.1734199

A. Orozco Estrada, R. C. Cruz Gómez, A. Cros, P. Le Gal

{"title":"Coalescence of lenticular anticyclones in a linearly stratified rotating fluid","authors":"A. Orozco Estrada, R. C. Cruz Gómez, A. Cros, P. Le Gal","doi":"10.1080/03091929.2020.1734199","DOIUrl":"https://doi.org/10.1080/03091929.2020.1734199","url":null,"abstract":"This study is devoted to laboratory experiments on the coalescence of two lenticular anticyclones in a linearly stratified rotating fluid. These anticyclones are generated by injecting small volumes of fluid at the centre of a rotating tank where a linearly stratified layer was previously prepared with salt. The characteristics of the interaction between the vortices are studied by visualisation and Particle Image Velocimetry (PIV) as a function of the initial separation distance between the vortices, the Coriolis parameter of the rotating table and the Brünt-Väisälä frequency of the density stratification. Our results show that the merging critical distance depends drastically on the Rossby radius of deformation of the vortices and are in complete agreement with previous numerical modelling of vortex coalescence. We have also observed that mergers involve three-dimensional processes as the vortices intertwine together possibly because of the presence of an elliptic instability that tilts the vortex cores. They are also accompanied by the emission of vorticity filaments and internal gravity waves radiation although we cannot prove that in our experiments these waves are solely due to the merging process.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"23 1","pages":"504 - 523"},"PeriodicalIF":1.3,"publicationDate":"2020-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88135796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Barotropic instability of a zonal jet on the sphere: from non-divergence through quasi-geostrophy to shallow water 球上纬向急流的正压不稳定性:从非辐散到准地转到浅水

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-02-24 DOI: 10.1080/03091929.2020.1724996

O. Shamir, N. Paldor, C. Garfinkel

{"title":"Barotropic instability of a zonal jet on the sphere: from non-divergence through quasi-geostrophy to shallow water","authors":"O. Shamir, N. Paldor, C. Garfinkel","doi":"10.1080/03091929.2020.1724996","DOIUrl":"https://doi.org/10.1080/03091929.2020.1724996","url":null,"abstract":"Two common approximations to the full Shallow Water Equations (SWEs) are non-divergence and quasi-geostrophy, and the degree to which these approximations lead to biases in numerical solutions are explored using the test bed of barotropic instability. Specifically, we examine the linear stability of strong polar and equatorial jets and compare the growth rates obtained from the SWEs along with those obtained from the Non-Divergent barotropic vorticity (ND) equation and the Quasi-Geostrophic (QG) equation. The main result of this paper is that the depth over which a layer is barotropically unstable is a crucial parameter in controlling the growth rate of small amplitude perturbations and this dependence is completely lost in the ND equation and is overly weak in the QG system. Only for depths of 30 km or more are the growth rates predicted by the ND and QG systems a good approximation to those of the SWEs, and such a convergence for deep layers can be explained using theoretical considerations. However, for smaller depths, the growth rates predicted by the SWEs become smaller than those of the ND and QG systems and for depths of between 5 and 10 km they can be smaller by more than . For polar jets, and for depths below 2 km the mean height in geostrophic balance with the strong zonal jet becomes negative and hence the barotropic instability problem is ill-defined. While in the SWEs an equatorial jet becomes stable for layer depths smaller than 3–4 km, in the QG and ND approximations it is unstable for layer depths down to 1 km. These result may have implications for the importance of barotropic instability in Earth's upper stratosphere and perhaps also other planets such as Venus.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"126 1","pages":"15 - 34"},"PeriodicalIF":1.3,"publicationDate":"2020-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88120412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

On magnetostrophic dynamos in annular cores 环形磁心磁转发电机的研究

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-02-20 DOI: 10.1080/03091929.2019.1685511

P. Roberts, Cheng-Chin Wu

{"title":"On magnetostrophic dynamos in annular cores","authors":"P. Roberts, Cheng-Chin Wu","doi":"10.1080/03091929.2019.1685511","DOIUrl":"https://doi.org/10.1080/03091929.2019.1685511","url":null,"abstract":"ABSTRACT Magnetostrophic dynamos are studied in an annular core, adapting the seminal work of Taylor [The magnetohydrodynamics of a rotating fluid and the Earth's dynamo problem. Proc. R. Soc. London A. 1963, 274, 274] for a fluid-filled core. The model consists of an inviscid fluid core and a concentric solid inner core. The fluid is supposed to obey the Boussinesq equations of motion and is driven into motion by a flow-forcing function consisting of the buoyancy force of an adverse radial temperature gradient, opposed by the Lorentz force of the self-sustained magnetic field. Coriolis forces act but inertial and viscous forces are ignored. Taylor (1963) showed how such a “magnetostrophic dynamo” can be found when there is no solid inner core, but his ideas have to be non-trivially generalised when an inner core is present. That is undertaken in this paper. In the 1993, CUP book, “Theory of Solar and Planetary Dynamos”, Hollerbach and Proctor gave examples in which the zonal flow created by a specified flow-forcing function may be singular on the “tangent cylinder”, an imaginary cylinder tangential to the inner core and parallel to the polar axis. It is shown here how this singularity is related to the flow-forcing function, and how discontinuities of other components of the fluid velocity on the tangent cylinder are determined by that function. In appendix A, an identity is established between the leading terms in the Fourier expansion of two of the cylindrical components of an arbitrary vector field. In appendix B, eight examples are given relevant to annular dynamos. In appendix C, equatorial symmetry is considered.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"1 1","pages":"356 - 408"},"PeriodicalIF":1.3,"publicationDate":"2020-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78930830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Thermal versus mechanical topography: an experimental investigation in a rotating baroclinic annulus 热与机械形貌:旋转斜压环的实验研究

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-02-03 DOI: 10.1080/03091929.2019.1697875

S. D. Marshall, P. Read

{"title":"Thermal versus mechanical topography: an experimental investigation in a rotating baroclinic annulus","authors":"S. D. Marshall, P. Read","doi":"10.1080/03091929.2019.1697875","DOIUrl":"https://doi.org/10.1080/03091929.2019.1697875","url":null,"abstract":"We present a series of experimental investigations in which a differentially-heated annulus was used to investigate the effects of topography on rotating, stratified flows. In particular, we investigate blocking effects via azimuthally varying differential-heating and compare them to previous experiments utilising partial mechanical barriers. The thermal topography used consisted of a flat patch of heating elements covering a small azimuthal extent of the base, forming an equivalent of a partial barrier, to study the difference between blocked and unblocked flow. These azimuthally-varying heating experiments produced results with many similarities to our previous experiments with a mechanical barrier, despite the lack of a physical obstacle or formation of bottom-trapped waves. In particular, a unique flow structure was found when the drifting flow and the topography interacted in the form of an “interference” regime at low Taylor number, but forming an erratic “irregular” regime at higher Taylor number. This suggests that blocking may be induced by either or both of a thermal or mechanical inhomogeneity. Evidence of coherent/persistent resonant wave triads was noted in both kinds of experiment, though the component wavenumbers of the wave-triads and their impact on the flow was found to depend on the topography in question.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"198 1","pages":"763 - 797"},"PeriodicalIF":1.3,"publicationDate":"2020-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72941560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Effect of respiratory changes in tracheal length on computed tomographic study of bronchial anatomy. 气管长度的呼吸变化对支气管解剖学计算机断层扫描研究的影响。

4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-02-01 Epub Date: 2019-10-24 DOI: 10.1007/s12630-019-01514-5

Satyen Parida

引用次数: 1

Wave turbulence: the case of capillary waves 波浪湍流:毛细管波的情况

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-01-28 DOI: 10.1080/03091929.2020.1715966

S. Galtier

引用次数: 2

Rossby waves in the ocean covered by compressed ice 被压缩冰覆盖的海洋中的罗斯比波

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-01-27 DOI: 10.1080/03091929.2020.1712716

Y. Stepanyants, I. Sturova

引用次数: 1

Stability of filaments of uniform quasi-geostrophic potential vorticity 均匀准地转位涡细丝的稳定性

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-01-27 DOI: 10.1080/03091929.2019.1704752

J. Reinaud

引用次数: 2

Mean flow generation due to longitudinal librations of sidewalls of a rotating annulus

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-01-20 DOI: 10.1080/03091929.2019.1692829

M. Kurgansky, T. Seelig, M. Klein, A. Will, U. Harlander

引用次数: 2

Life cycle of mesoscale eddies in the Gulf of Aden 亚丁湾中尺度涡旋的生命周期

IF 1.3 4区地球科学

Geophysical and Astrophysical Fluid Dynamics Pub Date : 2020-01-15 DOI: 10.1080/03091929.2019.1708348

Mathieu Morvan, P. L’Hégaret, Charly de Marez, X. Carton, Stéphanie Corréard, R. Baraille

{"title":"Life cycle of mesoscale eddies in the Gulf of Aden","authors":"Mathieu Morvan, P. L’Hégaret, Charly de Marez, X. Carton, Stéphanie Corréard, R. Baraille","doi":"10.1080/03091929.2019.1708348","DOIUrl":"https://doi.org/10.1080/03091929.2019.1708348","url":null,"abstract":"The Red Sea Water is a warm and salty water produced in the Red Sea by evaporation induced by strong solar radiation. This dense water mass exits the Red Sea through the Strait of Bab El Mandeb, and enters the Gulf of Aden as a density current between 400 and 1000 metre depth. In the Gulf of Aden, in situ and satellites observations have shown the impact of the deeply reaching eddies dominating the mesoscale dynamics, on the spreading of the Red Sea Water. In this paper, we study the life cycle of these mesoscale eddies in the Gulf of Aden by using a regional primitive equation model at mesoscale resolution, and an eddy-tracking algorithm. The mesoscale anticyclonic eddies are formed at the mouth of the Gulf of Aden, and subsequently drift westward into the gulf. Mesoscale anticyclones are long-lived compared to the cyclones. The cyclones result from the interaction of anticyclones with the coast and the sloping topography. The wind stress, the bathymetry and the surrounding eddy field drive the life cycle of eddies. Finally, Kelvin and internal waves are triggered along the northern and southern coasts.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"389 1","pages":"631 - 649"},"PeriodicalIF":1.3,"publicationDate":"2020-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75865824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8