March 21, 2025 marks the 80th birthday of Gregory Mikhailovich Reznik, an outstanding specialist in the theory of Physical Oceanography, head of the Laboratory of Geophysical Hydrodynamics, chief researcher at the Shirshov Institute of Oceanology of the Russian Academy of Sciences.

Gregory Reznik graduated from the Moscow Institute of Physics and Technology (University) in 1969 and completed his postgraduate studies at this institute under the supervision of Professor V.M. Kamenkovich in 1972. Starting from his senior years at the Institute, Gregory Reznik was closely associated with the Institute of Oceanology, where he began working on a permanent basis as a junior research fellow in September 1972, thus passing through all possible levels of scientific positions during 53 years of continuous work at the IOAN/IORAN, up to the head of the Laboratory and a member of the administrative and dissertation Academic Councils of the Institute.

Already the first publication of Gregory Reznik (G.M. Reznik. On the structure of boundary layers in the three-dimensional linear theory of wind circulation in a barotropic ocean // Bulletin of the USSR Academy of Sciences. Atmospheric and Oceanic Physics. 1970. Vol. 6. No. 11. Pp. 1163–1177), which presented the results of his diploma work, put the author among the leading Soviet theoretical oceanographers. This article marked the beginning of the 55th anniversary of Gregory Mikhailovich’s scientific activity.

G. M. Reznik and V. M. Kamenkovich laid the foundations for the theory of large-scale wind-driven ocean currents and, in particular, provided a rigorous justification for the mechanism of separation of western boundary currents such as the Gulf Stream and Kuroshio from the coast.

• V. M. Kamenkovich, G. M. Reznik. On the theory of stationary wind currents in a two-layer fluid // Bulletin of the USSR Academy of Sciences. Atmospheric and Oceanic Physics. 1972. Vol. 8. No. 4. Pp. 419–434
• V. M. Kamenkovich, G.M. Reznik. On the separation of a boundary current from the coast due to the influence of the bottom relief (linear barotropic model) // Reports of the USSR Academy of Sciences. 1972. Vol. 202. No. 5. Pp. 1061–1064.

 An important contribution to the theory of geophysical hydrodynamics is the work (G.M. Reznik. On the classification of quasi-geostrophic movements of the first kind // Oceanology. 1976. Vol. 16. Issue 4. Pp. 571–577), where G.M. Reznik showed that an adequate description of large-scale or mesoscale movements is essentially determined by the form of scaling of the vertical velocity. In modern terminology, in the first case, when it is assumed that all terms in the continuity equation are of the same order, it is customary to speak of geostrophic motions (or motions of the second kind), and in the second case, when the term with the vertical derivative of the vertical velocity is an order of magnitude smaller (in terms of the Rossby parameter), it is customary to speak of quasi-geostrophic motions (of the first kind).

The top scientific result of G.M. Reznik is obtaining, jointly with V.D. Larichev, a solution to two-dimensional solitary Rossby waves, which later became known as solitary eddies or Larichev-Reznik modons.

• Larichev V.D., Reznik G.M. On Two-Dimensional Solitary Rossby Waves // Reports of the USSR Academy of Sciences. 1976. Vol. 231. No. 5. Pp. 1077–1079
• Larichev V.D., Reznik G.M. Nonlinear Rossby Waves on a Large-Scale Current // Oceanology. 1976. Vol. 16. Issue. 2. P. 200–206

In essence, these works were the implementation of a social order from A.S. Monin, who set the authors the task of constructing a theory of synoptic eddies discovered during the implementation of large-scale polygon projects “Polygon-70”, “MODE-1”, “MODE-2” and “POLYMODE”.

The solutions obtained found numerous generalizations in the works:

• G. Flierl, J. McWilliams, V. Larichev, G. Reznik. The dynamics of baroclinic and barotropic solitary eddies // Dyn. Atm. Oceans. 1980. V. 5. No. 1. P. 1–41
• G.M. Reznik, W. K. Dewar. An analytical theory of distributed axisymmetric barotropic vortices on the β-plane // Journal of Fluid Mechanics. 1994. V. 269. P. 301–321
• J. Nycander. Refutation of stability proofs for dipole vortices // Physics of Fluids A. 1992. V. 4. No. 3. P. 467–476
• G.M. Reznik, G. G. Sutyrin. Baroclinic topographic modons // Journal of Fluid Mechanics. 2001. V. 437. P. 121–142
• D. Berson, Z. Kizner, Z Contraction of westward-travelling nonlocal modons due to the vorticity filament emission // Nonlinear Processes in Geophysics. 2002. V. 9. Nos. ¾. P. 265–279
• Z. Kizner, D. Berson, G. Reznik, G. Sutyrin. The theory of the beta-plane baroclinic topographic modons // Geophysical and Astrophysical Fluid Dynamics. 2003. Vol. 97. No. 3, P. 175–211
• Z. Kizner, G. Reznik, B. Fridman, R. Khvoles, J. McWilliams, J. Shallow-water modons on the f-plane // Journal of Fluid Mechanics. 2008. Vol. 603. P. 305–329
• Z. Kizner, G. Reznik. Localized dipoles: from 2D to rotating shallow water // Theoretical and Computational Fluid Dynamics. 2010. Vol. 24. P. 101–110]

G.M. Reznik made a significant contribution to the theory of geostrophic adjustment in works co-authored with his Australian and French colleagues

• G.M. Reznik, R. Grimshaw. Nonlinear geostrophic adjustment of long-wave disturbances in the shallow-water model on the equatorial beta-plane // Journal of Fluid Mechanics. 2004. V. 515, P. 135–170.].

In recent years, G.M. Reznik has been mainly interested in the problems of the dynamics of distributed and singular vortices in an external field, on which he has been successfully working with S.V. Kravtsov

• G.M. Reznik, S.V. Kravtsov. Singular vortices of the beta plane: a brief review and recent results // Marine Hydrophysical Journal. 2020. Vol. 36, No. 6. pp. 720–739
• S. Kravtsov, G. Reznik, (2021). Monopoles in a uniform zonal flow on a quasi-geostrophic-plane: effects of the Galilean non-invariance of the rotating shallow-water equations // Journal of Fluid Mechanics. 2021, Vol. 909. A23. DOI:10.1017/jfm.2020.906
• G. Reznik, S. Kravtsov. Monopoles in a zonal flow with constant shear on a quasi-geostrophic f-plane: effects of Galilean non-invariance // Physics of Fluids. 2021. V. 33. No. 11. P. 116606
• S. Kravtsov, G. Reznik. Quasi-geostrophic monopoles in a sheared zonal flow: influence of the beta-effect and variable shear // Physics of Fluids. 2023. V. 35. No. 1. S. 016606
• G.M. Reznik, S. Kravtsov. Quasi-geostrophic monopoles in sheared zonal jets and multiple-jet flows // Physics of Fluids. 2024. V. 36. No. 10. P. 106631

The above brief overview of publications reflects only a small part of the fundamental contribution of G.M. Reznik to various sections of geophysical hydrodynamics.

In general, G.M. Reznik has published more than 120 peer-reviewed articles and chapters in leading journals and highly rated monographs in the field of hydrodynamics, focusing on ocean and atmospheric physics. He never chased the number of publications, working on each article very carefully. G.M. Reznik always strives to analyze all possible solutions to the problem at hand, without breaking the work into smaller articles devoted to local problems. That is why many of his articles are so voluminous. In joint publications, G.M. Reznik always participates at least on an equal footing with other authors, in most cases playing a leading role.

For more than 40 years, G.M. Reznik has been giving various special courses at the Department of Thermohydrodynamics at MIPT. His students work in many research centers. In particular, his direct students are E. Benilov (Ireland), P. Berlov (UK), S. Kravtsov (USA).

On the eve of Gregory Mikhailovich's anniversary, his colleagues at the Institute of Oceanology came up with the idea of holding an international conference that would bring together all those who develop the areas of his scientific activity in their research. The Institute's administration supported this initiative. The organizing committee sent out invitations to a wide range of specialists in related fields of science. About 40 scientists responded to the invitations. The geography of the conference participants is wide: in Russia, these are Moscow, Obninsk, Nizhny Novgorod, Sevastopol, Rostov-on-Don, Novosibirsk, Vladivostok, foreign participants represent the USA, Australia, Israel, Great Britain, Ireland, France, Italy.

We are convinced that for everyone, the main motive for participating in the conference is the opportunity to express their respect and reverence to G.M. Reznik, the patriarch of Russian geophysical hydrodynamics.

On the threshold of his ninth decade, Gregory Mikhailovich is full of new scientific ideas. We wish our dear hero of the day good health and success in obtaining new bright scientific results.