Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/8945
DC Field | Value | Language |
---|---|---|
dc.contributor.authorall | Masina, S.; Istituto per lo studio delle Metodologie Geofisiche e Ambientali, CNR, Modena, Italy. | en |
dc.contributor.authorall | Pinardi, N.; Istituto per lo studio delle Metodologie Geofisiche e Ambientali, CNR, Modena, Italy. | en |
dc.date.accessioned | 2014-02-27T07:27:03Z | en |
dc.date.available | 2014-02-27T07:27:03Z | en |
dc.date.issued | 1993-08 | en |
dc.identifier.uri | http://hdl.handle.net/2122/8945 | en |
dc.description.abstract | We study the quasi-geostrophic merging dynamics of axisymmetric baroclinic vortices to understand how baroclinicity affects merging rates and the development of the nonlinear cascade of enstrophy. The initial vortices are taken to simulate closely the horizontal' and vertical structure of Gulf Stream rings. A quasigeostrophic model is set with a horizontal resolution of 9 km and 6 vertical levels to resolve the mean stratification of the Gulf Stream region. The results show that the baroclinic merging is slower than the purely barotropic process, The merging is shown to occur in two phases: the tirst, which produces clove-shaped vortices and diffusive mixing of vorticity contours; and the second, which consists of the sliding of the remaining vorticity cores with a second diffusive mixing of the intemal vorticity field. Comparison among Nof, Cushman-Roisin, Polvani et al, and Dewar and Killworth merging events indicates a substantial agreement in the kinematics of the DYOCRSS. Parameter sensitivity experiments show that the decrease of the baroclinicity parameter of the system, Γ^2, [defined as Γ^2 = (D^2 fo^2)/ (No^2 H^2)], increases the speed of merging while its increase slows down the merging. However, the halting elfect of baroclinicity (large Γ^2 or small Rossby radii of deformation) reaches a saturation level where the merging becomes insensitive to larger F2 values. Furthermore, we show that a regime of small Γ^2 exists at which the merged baroclinic vortex is unstable (metastable) and breaks again into two new vortices, Thus, in the baroelinic case the range of Γ^2 detemines the stability of the merged vortex. We analyze these results by local energy and vorticity balances, showing that the horizontal divergence of pressure work term [∇ *(pv)] and the relative-vorticity advection term (v * ∇ (∇ ^2 φ) trigger the merging during the first phase. Due to this horizontal redistribution process, a net kinetic to gravitational energy conversion occurs via buoyancy work in the region external to the cores of the vortices. The second phase of merging is dominated by a direct baroclinic conversion of available gravitational energy into kinetic energy, which in tum triggers a horizontal energy redistribution producing the final fusion of the vortex centers. This energy and vorticity analysis supports the hypothesis that merging is an internal mixing process triggered by a horizontal redistribution of kinetic energy. | en |
dc.description.sponsorship | The work has been financed by a grant from the Progetto Finalizzato "Calcolo Parallelo" | en |
dc.language.iso | English | en |
dc.publisher.name | American Meteorological Society | en |
dc.relation.ispartof | Journal of Physical Oceanography | en |
dc.relation.ispartofseries | 8/23 (1993) | en |
dc.subject | Ocean modeling | en |
dc.subject | Vortex dynamics | en |
dc.subject | Baroclinicity | en |
dc.subject | Eddies | en |
dc.title | The Halting Effect of Baroclinicity in Vortex Merging | en |
dc.type | article | en |
dc.description.status | Published | en |
dc.type.QualityControl | Peer-reviewed | en |
dc.description.pagenumber | 1618/1637 | en |
dc.subject.INGV | 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling | en |
dc.identifier.doi | 10.1175/1520-0485(1993)023<1618:THEOBI>2.0.CO | en |
dc.relation.references | Chamey, J. G., R. Fjortoft, and Von Neumann, 1950: Numerical integration of the barotropic vorticity equation, Tellus, 2, 237. Cresswe|l, G. ll.. |9822 The coalescence of two East Australian Current Warm-core eddies. Science, 215, 161-164. Cushman-Raisin, B., 1989: On the role of filamentation in the merging of anticyclonic lenses. I Phys. Oceanogr., 19, 253-258. --, and B. Tang, 1990: Geoslrophic turbulence and emergence of eddies beyond the radius of deformation. J. Phys. Oceanogr. 20, 1573-1575 Dewar, W. K., and P. D. Kjllworth, 1990: On the cylinder collapse problem, mixing, and the merger of isolated eddies, J. Phys. Oceanogr., 20, 1563-1575. Gill, A., and R. Griffiths, |981: Why should two anticyclonic eddies merge? Ocean Model., 41, 10. Griffith; R, W., and E. J. Hopfinger, 1986: Experiments with baroclinic vortex pairs in a rotating fluid. J. Fluid Mech., 178, 501- 518. -, and -, 1937; Coalescing of geostrophic vortices. J. Fluid Mech., 178, 73-97. Haidvogel, D. B., A. R. Robinson, and E. E. Schulman, 1980: The accuracy, efficiency, and stability of three numerical models with application to open ocean problems. J. Comput. Phys., 34, 1-53. Hogg N, G., and H. M, Stommel, 1985: The heton, an elementary interaction between discrete baroclinic - geostrophic vortices and its implication concerning eddy heat flow. Proc. R. Soc. London, A397, 1-20. McGi|licuddy, D. J., l987: Quasi-geostrophic modeling of isolated vortices. B. A. thesis, Department of Engineering Sciences, Harvard University. McWilliams, J. C., and N.J. Zabusky, 1982: Interaction of isolated vortices. l: Modons colliding with modons. Geophys, Astrophys. Fluid Dyn., 19, 207-227. Masina, S., and N. Pinardi, 1991: Merging of barotropic symmetric vortices: A case study for Gu|f Stream rings. ll Nuovo Cimento, 14C(6), 539-553C. Melander, M. V., N. J. Zabusky, and J. C, McWilliams, 1987: Axi-symmetrization and vorticity-gradient intensification of an isolated two-dimensional vortex through filamentation. J. Fluid Mech., 173. 137-159. -, - , and -, 1988: Symmetric vortex merger in two dimensions: Causes and conditions. J. Fluid Mech., 195, 303-340. Miller, R. N., A. R. Robinson, and D. B. Haidvogel, 1983: A baroclinic quasi-geostrophic open-ocean model. J. Comp. Phys., 50, 38- 70. Nofl, D., 1988: The fusion of isolated nonlinear eddies. J. Phys. Oceanagr.. 18, 887-905. -, and L. M. Simon, 1987: Laboratory experiments on the merging of nonlinear anticyclonic eddies. J. Phys. Oceanogr., 17. 343- 357. Olson, D. B., 1980: The physical oceanography of two rings observed during the cyclonic rings experiment. Part ll: Dynamics. J. Phys. Oceanogr., 10, 514-528. Overman, E. A., and N. J. Zabusky, 1982: Evolution and merger of isolated vortex structures. Phys. Of FIuids, 25, 1297-1305. Pavia, E. G.. and B. Cushman-Roisin, 1990: Merging of frontal eddies. J. Phys. Oceanagr., 20, 1886-1906. Pinardi, N., and A. R. Robinson, 1986: Quasi-geostrophic energetics of open ocean regions. Dyn. Atmos. Oceans, 10, 185-219. - , and R. F. Milliff, 1989: A note on consistent quasi-geostrophic boundary conditions in partially open, simply and multiply connected domains. Dyn. Atmos. Oceans. 14, 65-76. Polvani, L. M., N. J. Zabusky, and G. R. Flierl, |989: Two-layer geostrophic vortex dynamics. Part 1: Upper-layer V-states and merger. J. Fluid Mech., 205, 215-242. Rhines, P. B., 1977: The dynamics of unsteady currents. The Sea, Vol. 6, Wiley & Sons, 189-318 - , 1979: Geostrophic turbu|ence. Ann. Rev. Fluid Mech., 11, 401-41. Robinson, A. R., and L. J. Walstad, 1987: The Harvard open-ocean model: Calibration and application to dynamical process, forecasting, and data assimilation studies. J. Appl. Numer. Math. 3, 89-131. - , M. A. Spall, and N. Pinardi, 1988: Gulf Stream simulation and the dynamics of ring and meander processes. J. Phys. 0Ceanogr., 18, 1811-1853. - , J. A. Carton, N. Pinardi, ad C. N. K. Mooers, 1986; Dynamical forecasting and dynamical interpolation: An experiment in the California Current. J. Phys. Oceanogr. , 16, 1561-1579. Shapiro, R., 1970: Smoothing, filtering and boundary effects. Rev. Geophys. Space Phys., 2, 491-507. - , 1971: The use of linear filtering as a parameterization for atmospheric diffusion. J. Atmos. Sci., 28. 523-531. Verron, J., E. J. Hopfinger, and J, C. McWilliams, 1990: Sensitivity to initial conditions in the merging of two-layer baroclinic vortices. Phys. Fluids A, 2(6), 886-889. | en |
dc.description.obiettivoSpecifico | 4A. Clima e Oceani | en |
dc.description.journalType | JCR Journal | en |
dc.description.fulltext | restricted | en |
dc.relation.issn | 0022-3670 | en |
dc.relation.eissn | 1520-0485 | en |
dc.contributor.author | Masina, S. | en |
dc.contributor.author | Pinardi, N. | en |
dc.contributor.department | Istituto per lo studio delle Metodologie Geofisiche e Ambientali, CNR, Modena, Italy. | en |
dc.contributor.department | Istituto per lo studio delle Metodologie Geofisiche e Ambientali, CNR, Modena, Italy. | en |
item.openairetype | article | - |
item.cerifentitytype | Publications | - |
item.languageiso639-1 | en | - |
item.grantfulltext | restricted | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.fulltext | With Fulltext | - |
crisitem.author.dept | Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Bologna, Bologna, Italia | - |
crisitem.author.orcid | 0000-0001-6273-7065 | - |
crisitem.author.orcid | 0000-0003-4765-0775 | - |
crisitem.author.parentorg | Istituto Nazionale di Geofisica e Vulcanologia | - |
crisitem.classification.parent | 03. Hydrosphere | - |
Appears in Collections: | Article published / in press |
Files in This Item:
File | Description | Size | Format | Existing users please Login |
---|---|---|---|---|
Masina_and_Pinardi_1993.pdf | main article | 1.59 MB | Adobe PDF |
Page view(s) 20
259
checked on Apr 24, 2024
Download(s) 50
72
checked on Apr 24, 2024