Abstract
A spectral problem of the Orr–Sommerfeld type is considered to describe unstable disturbances of oceanic geostrophic currents with a linear vertical velocity profile by taking into account the vertical diffusion of buoyancy and friction. Numerical solutions are obtained for different values of the dimensionless parameters of the problem. Calculations of the spectra of eigenvalues and growth rates are compared with those of a similar problem for an ideal fluid. It is shown that (a) dissipation expands the range of wave numbers of unstable disturbances, (b) dissipation can increase the growth rates of baroclinic disturbances, (c) disturbances driven by the instability of the critical layer can grow faster than baroclinic disturbances, and (d) currents with a width equal to or less than the Rossby radius can be unstable; nearly circular (axisymmetric) unstable disturbances (submesoscale eddies) can develop in narrow currents or frontal zones.
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REFERENCES
Kuzmina, N.P., “On the hypothesis on the formation of large-scale intrusions in the Arctic basin,” Fundam. Prikl. Gidrofiz., 2016, vol. 9, no. 2, pp. 15–26.
Kuzmina, N.P., “Generation of large-scale intrusions at baroclinic fronts: An analytical consideration with a reference to the Arctic Ocean,” Ocean Sci., 2016, vol. 12, pp. 1269–1277. .https://doi.org/10.5194/os-12-1269-2016
Kuzmina, N.P., Skorokhodov, S.L., Zhurbas, N.V., and Lyzhkov, D.A., “On instability of geostrophic current with linear vertical shear at length scales of interleaving,” Izv., Atmos. Oceanic Phys., 2018, vol. 54, pp. 47–55.
Zhurbas, N.V., “On spectra of the eigenvalues in a model problem for describing the formation of large-scale intrusions in the Arctic basin,” Fundam. Prikl. Gidrofiz., 2018, vol. 11, no. 1, pp. 40–45.
Kuzmina, N.P., Skorokhodov, S.L., Zhurbas, N.V., and Lyzhkov, D.A., “Description of the perturbations of oceanic geostrophic currents with linear vertical velocity shear taking into account friction and diffusion of density,” Izv., Atmos. Oceanic Phys., 2019, vol. 55, pp. 207–217 (2019).
McIntyre, M.E., “Diffusive destabilization of the baroclinic circular vortex,” Geophys. Fluid Dyn., 1970, vol. 1, nos. 1-2, pp. 19–57.
Kuzmina, N.P. and Rodionov, V.B., “On baroclinicity effect on the formation of thermohaline intrusion in oceanic frontal zones,” Izv. Akad. Nauk: Fiz. Atmos. Okeana, 1992, vol. 28, nos. 10–11, pp. 1077–1086.
May, B.D. and Kelley, D.E., “Effect of baroclinicity on double-diffusive interleaving,” J. Phys. Oceanogr., 1997, vol. 27, 1997–2008.
Kuzmina, N.P. and Zhurbas, V.M., “Effects of double diffusion and turbulence on interleaving at baroclinic oceanic front,” J. Phys. Oceanogr., 2000, vol. 30, pp. 3025–3038.
Kuzmina, N.P., “On the parameterization of interleaving and turbulent mixing using CTD data from the Azores Frontal Zone,” J. Mar. Syst., 2000, vol. 23, pp. 285–302.
Merryfield, W.J., “Intrusions in double-diffusively stable Arctic waters: Evidence for differential mixing?” J. Phys. Oceanogr., 2002, vol. 32, pp. 1452–1439.
Kuzmina, N.P., Zhurbas, N.V., Emelianov, M.V., and Pyzhevich, M.L., “Application of interleaving models for the description of intrusive layering at the fronts of deep polar water in the Eurasian basin (Arctic),” Oceanology (Engl. Transl.), 2014, vol. 54, no. 5, pp. 557–566.
Kuzmina, N., Rudels, B., Zhurbas, V., and Stipa, T., “On the structure and dynamical features of intrusive layering in the Eurasian basin in the Arctic Ocean,” J. Geophys. Res., 2011, vol. 116, no. D11. https://doi.org/10.1029/2010JC006920
Eady, E.T. “Long waves and cyclone waves,” Tellus, 1949, vol. 1, no. 3, pp. 33–52.
Charney, J.G., “The dynamics of long waves in a baroclinic westerly current,” J. Meteorol., 1947, vol. 4, no. 5, pp. 135–162.
Green, J.S.A., “A problem in baroclinic stability,” Q. J. R. Meteorol. Soc., 1960, vol. 86, no. 368, pp. 237–251.
Miles, J.W., “Effect of diffusion on baroclinic instability of the zonal wind,” J. Atmos. Sci., 1965, vol. 22, pp. 146–151.
Cushman-Roisin, B., Introduction to the Geophysical Fluid Dynamics, Englewood Cliffs, NJ: Prentice Hall, 1994.
Eady, E.T. “Long waves and cyclone waves,” Tellus, 1949, vol. 1, no. 3, pp. 33–52.
Okeanologiya. Fizika okeana. Tom 2 (Oceanology. Ocean Physics. Vol. 2), Kamenkovich, V.M. and Monin, A.S., Eds., Moscow: Nauka, 1978.
Farrell, B.F., “The initial growth of disturbances in a baroclinic flow,” J. Atmos. Sci., 1982, vol. 39, pp. 1663–1686.
Kalashnik, M.V., “Resonant and quasi-resonant excitation of baroclinic waves in the Eady model,” Izv., Atmos. Oceanic Phys., 2015, vol. 51, pp. 576–584.
Lin, C.C., The Theory of Hydrodynamic Stability, Cambridge: Cambridge University Press, 1955.
Skorokhodov, S.L., “Numerical analysis of the spectrum of the Orr–Sommerfeld problem,” Comput. Math. Math. Phys., 2007, vol. 47, no. 10, pp. 1672–1691.
Skorokhodov, S.L., “Branching points of the eigenvalues of the Orr–Sommerfeld operator,” Dokl. Math., 2007, vol. 76, no. 2, pp. 744–749.
Skorokhodov, S.L. and Kuzmina, N.P., “Analytical–numerical method for solving an Orr–Sommerfeld-type problem for analysis of instability of ocean currents,” Comput. Math. Math. Phys., 2018, vol. 58, no. 6, pp. 976–992.
Skorokhodov, S.L. and Kuzmina, N.P., “Spectral analysis of model Couette flows in application to the ocean,” Comput. Math. Math. Phys., 2019, vol. 59, pp. 815–835.
Kalashnik, M.V., “On the theory of symmetric and asymmetric stability of zonal geostrophic currents,” Izv. Ross. Akad. Nauk, Fiz. Atmos. Okeana, 2001, vol. 37, no. 3, pp. 418–421.
Stern, M.E., Ocean Circulation Physics, New York: Academic Press, 1975.
Smyth, W.D. “Instabilities of a baroclinic, double diffusive frontal zone,” J. Phys. Oceanogr., 2008, vol. 38, pp. 840–861.
Fedorov, K.N., Fizicheskaya priroda i struktura okeanicheskikh frontov (Physical Nature and Structure of Oceanic Fronts), Leningrad: Gidrometeoizdat, 1983.
Zhurbas, V.M., Kuzmina, N.P., Ozmidov, R.V., Golenko, N.N. and Paka, V.T., “On the manifestation of subduction in thermohaline fields of the vertical fine structure and horizontal mesostructure in the frontal zone of the Azores Current,” Okeanologiya, 1993, vol. 33, no. 3, pp. 321–326.
Stern, M.E., “Lateral mixing of water masses,” Deep-Sea Res., Part A, 1967, vol. 14, pp. 747–753.
Munk, W. and Armi, L., in Proc. 12th ‘Aha Huliko’a Hawaiian Winter Workshop (2001), pp. 81–86.
ACKNOWLEDGMENTS
We thank an anonymous reviewer for helpful remarks.
Funding
This work was performed under the state assignment of Shirshov Institute of Oceanology, Russian Academy of Sciences (theme no. 0149-2019-0013).
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Translated by N. Tret’yakova
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Kuzmina, N.P., Skorokhodov, S.L., Zhurbas, N.V. et al. Effects of Friction and Buoyancy Diffusion on the Dynamics of Geostrophic Oceanic Currents with a Linear Vertical Velocity Profile. Izv. Atmos. Ocean. Phys. 56, 591–602 (2020). https://doi.org/10.1134/S0001433820060067
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DOI: https://doi.org/10.1134/S0001433820060067