About One Hypothesis of Generation of Large-Scale Intrusions in the Arctic Ocean
Abstract
Some analytical solutions are found for the problem of three-dimensional instability of a weak geostrophic flow with linear velocity shear taking into account the vertical diffusion of buoyancy. The analysis is based on the potential vorticity equation in a long-wave approximation when the horizontal scale of disturbances is taken much larger than the local baroclinic Rossby radius. It is hypothesized that the solutions found can be applied to describe stable and unstable disturbances of planetary scale with respect, especially, to the Arctic Basin where weak baroclinic fronts with typical temporal variability period of the order of several years or more are observed and the beta-effect is negligible. The unstable (growing with time) solutions are applied to describe the large-scale intrusions typical for the Arctic Basin. Double diffusion being typical and important driver of oceanic intrusions is included to the model by means of a simplest parameterization. Solutions obtained with and without effect of double diffusion are compared with structural features of large-scale intrusive layers observed in the Arctic Basin. Stable (decaying with time) solutions describe disturbances that, in contrast to the Rossby waves, can propagate both to the west and east depending on the sign of linear shear of geostrophic velocity. It is supposed that the analytical solutions found can be useful to validate numerical solutions of the eigen value problems devoted to the analysis of three-dimensional instability of slow baroclinic fronts with the consideration of vertical diffusion of buoyancy. Moreover, the analytical solutions obtained give analytical formulas for the phase velocities and growth/decay rates of disturbances that cannot, as a rule, be found exactly from numerical solutions of the eigen value problems.
About the Author
N. P. Kuzmina
P. P. Shirshov Institute of Oceanology of RAS
Russian Federation
Russian Federation
Moscow
References
1. Журбас В. М., Кузьмина Н. П., Кульша О. Б. Численное моделирование ступенчатого расслоения главного термоклина океана при вырождении термохалинных интрузий солевыми пальцами (численный эксперимент) // Океанология. 1987. Т. 27, № 3. С. 377—383.
2. Журбас В. М. и др. О проявлении процесса субдукции в термохалинных полях вертикальной тонкой структуры и горизонтальной мезоструктуры во фронтальной зоне Азорского течения // Океанология. 1993. Т. 33, № 3. С. 321—326.
3. Кузьмина Н. П. О вертикальной структуре трехмерного интрузионного расслоения океанских фронтов с существенной бароклинностью и термоклинностью // Океанология. 2001. Т. 41, № 3. С. 356—363.
4. Кузьмина Н. П., Руделс Б., Журбас Н. В. О структуре интрузий и фронтов в глубинном слое Евразийского бассейна и бассейна Макарова (Арктика) // Океанология. 2013. Т. 53, № 4. С. 463—475.
5. Кузьмина Н. П. и др. О роли вихрей и интрузий в процессах обмена в Балтийском халоклине // Океанология. 2008. Т. 48, № 2. С. 165—175.
6. Kuzmina N., Rudels B., Zhurbas V., Stipa T. On the structure and dynamical features of intrusive layering in the Eurasian Basin in the Arctic Ocean // J. Geophys. Res. 2011. V. 116. C00D11. doi:10.1029/2010JC006920.
7. Kuzmina N. P., Zhurbas V. M. Effects of Double Diffusion and Turbulence on Interleaving at Baroclinic Oceanic Fronts // J. Phys. Oceanogr. 2000. V. 30, № 12. P. 3025—3038.
8. Kuzmina N., Rudels B., Stipa T., Zhurbas V. The Structure and Driving Mechanisms of the Baltic Intrusions // Journal of Physical Oceanography. 2005. V. 35, N. 6. P. 1120—1137.
9. Kuzmina N. P. On the parameterization of interleaving and turbulent mixing using CTD data from the Azores Frontal Zone // J. Mar. Sys. 2000. V. 23. P. 285—302.
10. Kuzmina N. P., Lee J. H., Zhurbas V. M. Effects of turbulent mixing and horizontal shear on double-diffusive interleaving in the Central and Western Equatorial Pacific // J. Phys. Oceanogr. 2004. 34. P. 122—141.
11. McDougall T. J. Double-diffusive interleaving. Part 1: Linear stability analysis // J. Phys. Oceanogr. 1985. V. 15. P. 1532—1541.
12. Niino H. A linear stability theory of double-diffusive horizontal intrusions in a temperature-salinity front // J. Fluid. Mech. 1986. V. 171. P. 71—100.
13. Rudels B., Bjork G., Muench R. D., Schauer U. Double-diffusive layering in the Eurasian Basin of the Arctic Ocean // J. Mar. Syst. 1999. V. 21, N. 1—4. P. 3—27.
14. Stern M. E. Lateral mixing of water masses // Deep-Sea Res. 1967. V. 14, N. 12A. P. 747—753.
15. Toole J. M., Georgi D.T. On the dynamics and effects of double-diffusively driven intrusions // Prog. Oceanog. 1981. V. 10. N 2. P. 123—145.
16. Yoshida J., Nagashima H., Niino H. The behavior of double-diffusive intrusion in a rotating system // J. Geophys. Res. 1989. V. 94. P. 4923—4937.
17. Rudels B. et al. Double-Diffusive Convection and Interleaving in the Arctic Ocean — Distribution and Importance // Geophysika. 2009. P. 199—213.
18. Кузьмина Н. П., Родионов В. Б. О влиянии бароклинности на образование термохалинных интрузий в океанских фронтальных зонах // Изв. АН СССР. Физ. атм. и океана. 1992. Т. 28, № 10—11. С. 1077—1086.
19. Kuzmina N., Lee J. H. Driving Forces of Interleaving in the Baroclinic Front at the Equator // Journal of Physical Oceanogr. 2005. V. 35, N. 12. P. 2501—2519.
20. Radko T. Mechanics of merging events for a series of layers in a stratified turbulent fluid // J. Fluid Mech. 2007. P. 251—273.
21. May B. D., Kelley D. E. Effect of baroclinicity on double-diffusive interleaving // J. Phys. Oceanogr. 1997. 27. P. 1997—2008.
22. Eady E. T. Long waves and cyclone waves // Tellus. 1949. V. 1, № 3. P. 33—52.
23. Walsh D., Carmack E. The nested structure of Arctic thermohaline intrusions // Ocean Modelling. 2003. V. 5. P. 267—289.
24. Stern M. Ocean circulation physics. International Geophysics Series. V. 19. Academic Press, 1975. 245 p.
25. Баренблатт Г. И. Автомодельные явления — анализ размерностей и скейлинг. Долгопрудный: Издательский дом Интеллект, 2009. 216 с.
26. Кузьмина Н. П. и др. Применение моделей интерливинга для описания интрузионного расслоения на фронтах глубинной полярной воды Евразийского бассейна (Арктика) // Океанология. 2014. Т. 54. С. 594—604.
27. May B. D., Kelley D. E. Growth and steady stage of thermohaline intrusions in the Arctic Ocean // J. Geophys. Res. 2001. V. 106. P. 16783—16794.
28. Merryfield W. J. Intrusions in Double-Diffusively Stable Arctic Waters: Evidence for Differential mixing? // J. Phys. Oceanogr. 2002. V. 32, N. 5. P. 1452—1439.
29. McIntyre M. E. Diffusive destabilization of the baroclinic circular vortex // Geophys. Fluid Dyn. 1970. V. 1, N. 1—2. P. 19—57.
Review
For citations:
Kuzmina N.P. About One Hypothesis of Generation of Large-Scale Intrusions in the Arctic Ocean. Fundamental and Applied Hydrophysics. 2016;9(2):15-26. (In Russ.)
Views:
70
Email this article 