ISSN 00014370, Oceanology, 2011, Vol. 51, No. 4, pp. 554–567. © Pleiades Publishing, Inc., 2011. Original Russian Text © A.G. Zatsepin, V.I. Baranov, A.A. Kondrashov, A.O. Korzh, V.V. Kremenetskiy, A.G. Ostrovskii, D.M. Soloviev, 2011, published in Okeanologiya, 2011, Vol. 51, No. 4, pp. 592–605.
MARINE PHYSICS
Submesoscale Eddies at the Caucasus Black Sea Shelf and the Mechanisms of Their Generation A. G. Zatsepina, V. I. Baranovb, A. A. Kondrashovb, A. O. Korzhb, V. V. Kremenetskiya, A. G. Ostrovskiia, and D. M. Solovievc a Shirshov
b
Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia Atlantic Branch of the Shirshov Institute of Oceanology, Russian Academy of Sciences, Kaliningrad, Russia c Marine Hydrophysical Institute, National Academy of Sciences, Sevastopol, Ukraine email:
[email protected] Received October 13, 2009
Abstract–The results of observations of submesoscale eddies (with a diameter of 2–8 km) on the narrow Black Sea shelf are presented. These observations were carried out in the Gelendzhik region in the autumn seasons of 2007–2008 using traditional and new methods of hydrophysical investigations. The mechanisms of generation of such eddies are discussed. DOI: 10.1134/S0001437011040205
INTRODUCTION On average, the positive (cyclonic) vorticity of the wind field over the Black Sea shapes the basinscale cyclonic water circulation [11, 16]. The Rim Current of the Black Sea, which encompasses the whole deep water zone of the sea [2, 12, 15], is an important ele ment of this circulation. The water dynamics of the Black Sea is extremely variable because the largescale wind forcing is timedependent and involves fluctua tions of different time periods, ranging from synoptic to interannual, while the Rim Current exhibits insta bility. Mesoscale eddy dynamics represents one of the most convincing pieces of evidence for such variabil ity. The main mechanism of its origination is in the Rim Current baroclinic instability, which is active dur ing periods of the absence of wind (Ekman’s) circula tion pumping [17, 19, 3]. This instability in the domain of the Rim Current results in the occurrence of large meanders and eddies the diameters of which come to (2–7)Rd, where Rd is the local Rossby’s radius of baroclinic deformation. The upper limit of Rd = 15– 20 km in the deepwater Black Sea region, so that the upper limit of the diameter of mesoscale eddies exceeds 100 km. These longlived (up to eight months) quasigeostrophic eddies and eddy pairs support hori zontal water exchange between the central and coastal (shelfandslope) sea zones and influence the struc ture and localization of the Rim Current [18, 3]. At present, the water dynamics of the Black Sea shelf and, specifically, of its Russian part belongs to the leaststudied problems of the Black Sea oceanography. Such studies are important for securing the ecological safety of this region of high recreational and industrial
significance. The urgency of solving this problem is due to the need for adequate assessment of the ability of the shelf–coastal ecosystem to withstand the increasing anthropogenic load. The shelf of the Caucasus margin of the Black Sea is only 2–10 km wide, which is substantially narrower than the Rim Current width or the diameter of mesos cale eddies in the deepwater basin of the sea. Thus, the narrow Caucasus shelf represents a zone of dissipa tion of the dynamical structures localized over the continental slope and/or the deepwater basin. It is natural to expect that these dynamical structures have a paramount impact on the dynamics of the shelf waters. This has been corroborated by observations [8, 9, 7, 13]. However, in addition to the influence of the deepwater zone dynamics, the shelf currents are characterized by the eigenmodes of the variability and strongly depend on the wind forcing (a coastal wind induced upwelling, for example) and the continental runoff. Sometimes, these factors prevail [6, 1, 4]. The impact of the bottom topography and the coastal orog raphy can be quite considerable as well. Thus, it is pos sible to conclude that the water dynamics of the Cau casus shelf, influenced by different external factors, has to exhibit specific features and exhibit a higher level of variability in the range of smaller spatial–tem poral scales (1–10 km, 1–102 h) as compared to the deepwater zone. The longterm observations of currents in the Black Sea, carried out by researchers at the Southern Branch of the Shirshov Institute of Oceanology, Rus sian Academy of Sciences, with the help of mechani cal current meters at moored buoy stations revealed
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Fig. 1. Photograph of a submesoscale cyclonic eddy appearing as a spiral slick structure (the arrow marks its center) in the shelf zone of the Black Sea. The ships at anchor in the photograph indicate that the current on the shelf beyond the eddy was directed to the southeast (June 19, 2007; photograph by A.V. Grigoriev).
that the Caucasus shelf current is mostly bimodal in character. Moreover, it is directed to the northwest lengthwise to the shore in most cases (like the Rim Current), but it also frequently moves in the opposite direction [7]. The frequent occurrence of the south east bound current has been attributed to the passing across the observation point of coastal anticyclonic eddies (CAEs) that create a nearshore current oppo site to the Rim Current. When doing so, some authors have mistakenly classified the mesoscale anticyclones with centers in the deepwater basin as CAEs [14] although it is reasonable to consider as coastal eddies only the shelf anticyclones and cyclones the horizontal scales of which are smaller by an order of magnitude. We studied the water dynamics and processes of horizontal and vertical exchange on the narrow shelf and upper continental slope of the Black Sea near the town of Gelendzhik in 2006–2008 using a new approach to investigation and new measurement tech niques. The description of this approach, the essence of which lies in securing a high measurement resolu OCEANOLOGY
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tion in time and space adequate to the dynamical structures on the shelf, as well as the main results of the observations of 2006, are given in [5]. In the present study, we present the results of observations accom plished during the fall seasons of 2007 and 2008. We focus on the description of submesoscale (2–8 km) eddies with a radius smaller than the magnitude of the Rossby baroclinic deformation radius on the shelf and on the discussion of the mechanisms of their origina tion. One of these eddies was well manifested on the surface as a spiral slick structure and in the orientation of ships at anchor. It was photographed from a high bank by a member of the expedition (Fig. 1). These eddies are ageostrophic and, supposedly, shortlived (their lifetime comes to several hours, but does not exceed several days). It should be noted that such eddies were recently discovered on the Caucasus shelf of the Black Sea and some of their features were described based on analytical treatment of SAR images [10].
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METHODS AND MEANS OF OBSERVATIONS The methods and means of observations involved (1) analytical treatment of current satellite infor mation in the IR and visible ranges (the temperature and color of the sea surface); (2) ship transects across the shelf and continental slope zones with regular stations for vertical CTD profiling; (3) a quasiinstantaneous spatial survey of the cur rent field with the help of a towed ADCPprofiler; and (4) longterm (several days long) vertical profiling of the current’s velocity with an ADP bottom acoustic current profiler. We analyzed the satellite data in order to obtain qualitative ideas about the structure and strength of the surface currents in the sea region, dynamically cou pled with the study area, and for interpretation of the results of the CTDcross sections and of a spatial sur vey of the horizontal current velocity field conducted aboard the R/V Akvanavt. We used a series of sequen tial images of the northeasternpart of the Black Sea in the field of the sea surface temperature (SST) received from NOAA satellites in the HRPT mode (spatial res olution 1 km) by a station of the Marine Hydrophysi cal Institute, National Academy of Sciences (Ukraine, Sevastopol). Hydrological observations were carried out aboard the R/V Akvanavt perpendicular to the normalto shore transect and at individual stations for CTDpro filing (electric conductivity, temperature, pressure) on the shelf and upper continental slope. The soundings were performed with a SeaBird Electronics (SBE) 19 plus probe using an armored cable and ship’s winch. The goal of such profiling was to reveal the hydrologi cal structures of the shelf waters, which is necessary for processing and interpretation of the ADCP data. We used a towed RDI WorkHorse Mariner ADCP acousticDoppler profiler (300 kHz) to obtain quasi instantaneous patterns of the threedimensional field of the horizontal current’s velocity in the shelf zone. The profiler was installed in a specially designed nacelle in such a way that the instrument’s axis was directed vertically downward when the nacelle was towed behind the vessel on a cablerope from the stern winch. It took only 5–8 h to perform four to seven normaltoshore transects 2–4 km apart. The instru ment was able to produce representative measure ments (accurate to 2–3 cm s–1) in the mode of “bot tom tracking” only, i.e., when it received a signal reflected from the sea bottom. This operation mode
was successful when the instrumenttobottom dis tance did not exceed 250 m. Thus, the measurements of the velocity field were reliable only in the shelf zone and above the upper slope. In addition to determining the current, the ADCP measures the level of the backscattered sound propor tional to the concentration of the soundscattering particles. This quantity is a good indicator of seasonal thermocline depth, since it exhibits the fastest vertical changes specifically in the area of the thermocline. It has been observed that the current’s velocity differ in magnitude and direction above and below the layer of maximal gradient of the backscattered sound intensity. It was decided to average the velocity vectors for each of these layers. In what follows, we use the mean values of the current’s velocity for the upper layer (shallower than the seasonal thermocline) when discussing the results of the ADCP surveys and the directions of water transport. In addition to the acoustic profiler of currents as a towed instrument, we used a similar ADPtype device for bottom installation (250 kHz, by SONTEK). It was placed in gimbals in a duralumin construction resem bling a truncated pyramid. The latter was placed on the sea bottom in such a way that the instrument’s axis is vertical while the emitters are directed upward. Thanks to this, the instrument recorded the current’s velocity profile from the bottom construction almost to the sea surface. There was 32 m of water at the site of construction’s deployment, which was close to Golubaya Bay. WORKS PERFORMED AND RESULTS OF RESEARCH October 2007. The satellite imagery in the temper ature field (Fig. 1) illustrates the hydrodynamical situ ation during our observations from October 17 to 25 in the northeastern Black Sea within the vast area between the townships of Anapa and Tuapse (Fig. 2). As it follows from these images, the structure of the current’s field was determined by a large eddy dipole with the cyclonic eddy “C” to the northwest, centered approximately at 44°N, 36°30′E, and the anticyclonic eddy “A” to the southeast around the point at 43°30′N, 38°E. It is known that the eddy pairs are able to pro gressively move perpendicular to the axis of symmetry in the direction determined by the eddies' localization. In this situation the cyclone was located on the right. Therefore, the eddy pair, the horizontal scale of which was as large as 120 miles, strove to move toward the coast. It served as a sort of “press” that pressed the cur
Fig. 2. Satellite images of the SST field in the northeastern Black Sea on October 17, 2007, 10:21 a.m. GMT (top) and on October 19, 2007, 10:02 a.m. GMT (bottom) that illustrate the occurrence of the large eddy pair (C as cyclone and A as anticyclone) and of the alongshore current and mesoscale eddy structures (A1, C1, and A2) in the shelfslope zone of the sea. OCEANOLOGY
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rents against the shore in the shelfslope zone. This circumstance prevented the growth of current mean ders and restricted the horizontal scale of mesoscale eddies (A1, C1, and C2), which did not exceed 20–30 km (Fig. 2). Analytical treatment of the satellite images revealed that, on October 17 and 19 (Fig. 2), the study area (the shelf in the vicinity of Gelendzhik) was in the domain of influence of coastal anticyclonic eddy A1. This eddy has to generate a southeast bound current at the shelf and upper continental slope. This is also evi denced by the data from the stations of CTDprofiling in the transect that was occupied by the R/V Akvanavt on October 18, 2007. The isolines of temperature, salinity, and density in the respective cross section were tilted upward toward the shore. With such a slope of isolines, the geostrophic current must be directed to the southeast. Indeed, the ADCP survey of the same day revealed a predominantly southeasterly direction of the current (Fig. 3a). The current’s velocity peaked at the outer edge of the shelf with 50–80 m of water, where it was as strong as 30–40 cm s–1. Here the cur rent mainly followed the isobaths. In the inner shelf with less than 40 m of water, the current was not as strong and regular. The current’s velocity made up 5– 15 cm s–1, and the current was eddylike in character. The submesoscale cyclonic eddy beyond Gelendzhik Bay was the most clearly distinguished dynamical structure. Its diameter measured about 6 km, which is smaller than the magnitude of the local baroclinic Rossby deformation radius for shelf waters. Therefore, this eddy cannot have been quasistationary and quasigeostrophic. Supposedly, its origination related to the shear instability of a coastal current. In this case, in the presence of the southeasterly current over the continental slope and the outer part of the shelf, its inner part has to be dominated by cyclonic eddies, or by anticyclonic ones in the presence of a northwesterly current. Observations corroborate this hypothesis. Accord ing to satellite images, the study area was influenced by the cyclonic mesoscale eddy C1 on October 19–20. In contrast to the data of the ADCP survey on October 18, the survey of October 20 revealed a northwesterly current at the outer shelf (Fig. 3b). The current’s velocity was 35–45 cm s–1. The current exhibits insta bility at the inner shelf dominated by anticyclonic meanders and, apparently, eddies. The horizontal size of these meanders made up 4–6 km. September 2008.The satellite images of the SST field clearly illustrate the general hydrodynamical conditions in the northeastern Black Sea within the wide sector from Anapa to Sochi during observations on September 27–30 (Fig. 4). It is evident that the Rim Current jet between Tuapse and Anapa is influ enced by two large cyclonic eddies with diameters
exceeding 50 km. They occurred in the deepwater area, as designated with the large light arrow in the fig ure. These eddies press the Rim Current against the shore and accelerate its jet up to 50–60 cm s–1, according to satellite data. Such a hydrodynamical pattern is occasionally observed in the Black Sea and can be regarded as a manifestation of a “negative vis cosity” (the coherent eddy structures transfer the momentum to the Rim Current, i.e., from smaller scales to larger ones). In the context of the present study, we are inter ested in the impact of the fast and narrow Rim Cur rent’s jet on the water dynamics and its changes in the shelf zone of the sea. Such conditions substantially differ from those in 2007. During the observations of this year, the Rim Current was weak, being dominated by eddy structures, while the shelf zone near the town of Gelendzhik was influenced first by the anticyclonic eddy and later by the cyclonic one. Moreover, the cen ters of these eddies occurred in the deepwater zone of the sea. Figures 5a and 5b show the profiles of temperature and electric conductivity recorded in the shelf zone near the town of Gelendzhik on September 27 and 30, respectively. It is seen that stratification is twolayer in character above the 60m depth level: mixed layer occupies the upper 27–30 m of water, and the CIL waters occur below depths of 37–42 m, while a sharp thermocline with a temperature jump of 12°С lies between these quasihomogeneous layers. The measured parameters of shelf waters’ stratifi cation allowed us to estimate the baroclinic Rossby deformation radius: Rd = [g(Δρ/ρ)H]0.5f –1 = 8 km, where Δρ = 2 × 10–3 g cm–3 is the density difference between the upper and lower layers, ρ = 1.0 g cm–3 is the water density, g = 103 cm s–2 is the acceleration of gravity, H = 30 m is the upper layer thickness, and f = 10–4 s–1 is the Coriolis parameter. This value of the Rossby radius is comparable to or even exceeds the shelf’s width. In addition, the Rossby number is of the order on unity for a shelf shear flow. Thanks to this, the intrashelf water dynamics has to be ageostrophic. In line with the stratification, current’s structure at shelf is doublelayer in character. Fig. 6 displays the north ern (a) and the eastern (b) components of current’s velocity in the transect of October 28 passing through the center of the coastal submesoscale anticyclonic eddy a1. It is evident that strong currents (up to 50 cm s–1) occur in an upper layer 30 m thick. The velocity is slower than 15 cm s–1, and eddy dynamics is lacking in the underlying layers. Thus, enhanced eddy dynamics occurred exclusively above the seasonal thermocline, while the lower layer remained dynamically passive. Supposedly, this is why the eddy a1 was deprived of topographic binding and, as will be shown below, was able to leave the shelf and travel into waters above the OCEANOLOGY
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Fig. 4. The satellite image of the SST field in the northeastern Black Sea on September 28, 2008, 6:27 p.m. GMT. Large light arrows designate the cyclonic eddies of the deepwater area, while the small arrow marks a submesoscale anticyclonic coastal eddy a1.
continental slope. During this period the Rim Cur rent’s jet was sustainable and its core occurred above the upper continental slope quite close to the shore. In addition, a strong shear in the horizontal current’s velocity (~104 s–1), having an anticyclonic sign, took place in the shelf area. The velocity shear could serve as a source of vorticity and energy for origination of submesoscale anticyclonic eddies in the shelf zone of the sea. Additionally, the shoreline orography facili tated origination of the anticyclonic eddies on the shelf. The shelf zone in the Gelendzhik neighborhood belongs to a “depression” of the shoreline. In the east, this depression is limited by the cape of Idokopas (Fig. 4) located 15 km east of Gelendzhik. Near the cape the shelf is quite narrow (3–4 km) and the Rim Current comes directly to the shore. The width of the shelf zone doubles west of the cape. This circumstance cre
ates a precondition for detachment of the current from the shore and for formation of a beyondtheobstacle eddy. Both mechanisms of vortex shedding (current detachment and shear instability) must interact and facilitate generation and development of the coastal anticyclonic eddies, as was observed in reality. Speculation on the occurrence of a small (5–6 km in diameter) eddy in the extension of the shelf west of the cape of Idokopas began when we examined the sat ellite images of the SST field on September 27. Unfor tunately, fairly dense cloudiness prevented the consid eration of a vast aquatic area and to establishment of characteristic features of the water dynamics in the region. However, fair weather prevailed for the subse quent four days (September 28 to October 1), which allowed us to fully use the satellite information to OCEANOLOGY
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monitor travels and transformations of eddy struc tures. Figures 7a–7d show four subsequent satellite images of the SST in the northwestern Black Sea from September 28 to October 1. Here dashed circles desig nate the localization and approximate size of the coastal anticyclonic eddy a1. If we affirm that this eddy was generated on September 27 in the extension of shelf between the cape of Idokopas and the town of Gelendzhik, then, to all appearances, the eddy subse quently increased in size and moved to the west– northwest of the town of Gelendzhik on September 28. By this time, it already covered the whole shelf zone; i.e., its diameter measured 8–10 km. The eddy contin ued to travel in the same direction and grow in size during the subsequent days. By September 29 the eddy’s diameter was about 15 km and only half of the eddy belonged to the shelf zone, while its seaward part was located above the continental slope. Extension of the eddy into the continental slope area enhanced its interaction with the Rim Current. The eddy acceler ated its progressive motion under the pressure of the Rim Current’s jet. For the first two days, its northwest travel velocity measured about 7 cm s–1, but it increased to 25–40 cm s–1 from September 29 to October 1. In two days the eddy travelled more than 50 km and appeared in the area between the towns of Novorossiysk and Anapa. Its diameter continually OCEANOLOGY
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increased and became as large as 20 km by October 1. It took a few days to turn the submesoscale eddy into a mesoscale one. We failed to monitor its further fate because of cloudiness. We now consider the data of the ADCP survey. Maps of the horizontal current’s velocity, averaged over the thickness of the upper quasihomogenous layer, are presented in Figs. 8a–8d. The dashed con tours mark the observable eddies. The position and size of the eddy a1 are given in Fig. 8a approximately, because the ADCP survey on September 27 covered a limited area and involved only the extreme western edge of this eddy. However, the survey on September 28 covered a greater aquatic area and permitted us to outline the whole eddy a1 that appeared on this day near the town of Gelendzhik. Moreover, the eddy’s localization from the ADCP data (Fig. 8b) agrees well with that from the satellite SST pattern for the same data (Fig. 7b). According to the nextday ADCP sur vey (Fig. 8c), the eddy a1 substantially increased in diameter and displaced westward, which agrees with the image for the same day as well (Fig. 7c). The joint use of satellite information and data of the ADCP survey of the horizontal current’s velocity field allowed us not only to trace the evolution and movement of the eddy a1, but to estimate its cinematic and dynamical characteristics at different instants as well. They are given in the table.
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They involve Rv as the eddy’s radius (the distance from its center to the contour of maximal orbital velocity); Vorb as the maximal orbital velocity of rota tion of particles in the eddy; Vtr as the velocity of move ment of the eddy’s center (translational velocity); ω = 2π/T = Vorb/Rν as the angular frequency of the eddy’s rotation; T as the rotation period; Ro = ω/f as the Rossby number, where f = 10–4 s–1 is the Coriolis parameter; and Rd/Rv, Vorb /Vtr. The last three dimen sionless parameters give us a measure of the submesos cale nature and ageostrophicity degree of the eddy a1. As follows from the table, the anticyclonic eddy a1 was of submesoscale nature and ageostrophic (Rd /Rv >2;
Ro > 1), while its orbital rotation velocity was much higher than the translational one (Vorb/Vtr = 5–7) in the beginning of eddy’s evolution. At the end of the obser vation period, it “grew up” to the mesoscale and quasigeostrophic state (Rd/Rv < 1; Ro < 0.5). How ever, the eddy’s entrance into the Rim Current domain resulted in considerable acceleration of its transla tional velocity, which became approximately equal to the orbital one (Vorb/Vtr ≈ 1). This circumstance casts doubt on the possibility of the continued existence of the eddy as an isolated dynamical formation. How ever, it is possible that, as a result of slowing of the Rim Current west of the Utrish Cape, this eddy has restored
The values of kinematic and dynamic characteristics of the submesoscale eddy a1 at different times Date September 28, 2008 September 29, 2008 September 30, 2008 October 1, 2008
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its isolation and continues to exist. It should be noted that eddy a1 generated a cyclonic velocity shear near the shore when traveling within the shelf. Instability of this shear current caused, apparently, origination of a small cyclonic eddy c1 localized between the shore and anticyclonic eddy a1 on September 29 (Fig. 8c). Presumably, this cyclonic eddy existed for less than a day, because it was absent in the study area already on September 30 (Fig. 8d) according to the ADCP survey, as was the anticyclonic eddy a1 that moved far north west (see also Fig. 7d). However, one more submesos cale anticyclonic eddy a2 appeared on September 30 at the site where eddy a1 was supposedly created on Sep tember 27 (Fig. 8d). The subsequent fate of the eddy a2 is unknown. Nevertheless, it is reasonable to sup pose that a submesoscale anticyclonic eddy periodi cally forms in the “depression” of the shore line west of the Idokopas Cape in the presence of a strong Rim Current jet. Being born as a vortex of a detached flow, OCEANOLOGY
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it is “fed” by the vorticity and the energy of the velocity shear. Its diameter grows until the eddy itself is entrained by the Rim Current flow and transported with the latter to the northwest. Next, a new eddy appears in its place. Some confirmation of this hypothesis can be gleaned from the data of the bottom ADCP. It was installed at a depth of 32 m across from Golubaya Bay and recorded the profiles of the cur rent’s velocity from 2 p.m. on September 29 to 4 p.m. on October 1 (Fig. 9). According to this figure, less than two days after the sign of the eastern component of the current’s velocity changed from positive to neg ative thanks to the departure of eddy a1, the eastern component of the current’s velocity again changed its sign to positive, which most probably was due to the arrival of the eddy a2. The scheme of the process of eddy shedding beyond the ledge in the zone of flow extension is dis played in Fig. 10. Here U is the current’s velocity in the
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Fig. 9. The eastern component of the current velocity recorded with the bottom ADP on the shelf at a depth of 32 m in the area of Golubaya Bay from 2:00 p.m., September 29, 2008, to 4:00 p.m. October 1, 2008.
core of the incoming flow; D is the width (height) of the ledge; and T is the period of eddy origination, its detachment, and entrainment by the flow. According to laboratory experiments in a nonrotating fluid, the dimensionless frequency of vortex breakdown behind the obstacle, or Strouhal number St = D/UT, is almost constant and equals 0.1–0.3 in a wide range of Reynolds numbers (Re = 200–200 000). Assuming that for the case in question U ≈ 40 cm s–1, D ≈ 8 km, and T ≈ 2 days, we obtain St ≈ 0.1, which coincides with the lower of the above limits. Since the periodic occurrence of eddy and its departure from the shelf are accompanied by intense water exchange, we can assume that ventila tion of the upper layer waters on the Gelendzhik shelf takes only two days under the described conditions.
U T D
Fig. 10. Diagram of periodic formation of submesoscale eddies in the shelf zone at the site of detachment of a cur rent beyond the obstacle and of eddy separation due to the incident flow.
ACKNOWLEDGMENTS This work was supported by the project “Impact of Large and Mesoscale Water Dynamics on Processes of Intrabasin Exchange: Laboratory Experiment” of Program no. 20 of the Presidium of the Russian Acad emy of Sciences, as well as by the Russian Foundation for Basic Research (projects nos. 080500183, 0805 00633, 090590715, 090592501, 090513527, 11 0500804, and 110500830). REFERENCES 1. N. A. Aibulatov, P. O. Zav’yalov, and V. V. Pelevin, “Features selfcleaning hydro Russian Black Sea coastal zone near river mouths,” Geoekologiya, 4, 301–310 (2008). 2. O. N. Bogatko, S. G. Boguslavskii, Yu. M. Belyakov, and R. I. Ivanov, “Surface Currents of the Black Sea,” in Integrated Studies of the Black Sea (MGI AN USSR, Sevastopol, 1979), pp. 25–33 [in Russian]. 3. A. I. Ginzburg, A. G. Zatsepin, V. V. Kremenetskii, and V. B. Piotukh, “Mesoscale Dynamics of the Black Sea Waters,” in Oceanology at the Start of the 21st Century (Nauka, Moscow, 2008), pp. 11–42 [in Russian]. 4. V. M. Zhurbas, P. O. Zav’yalov, and A. S. Sviridov, “Transfer of Small River Runoff by the Alongshore Baroclinic Sea Current,” Okeanologiya, 51 (3), 412– 420, 2011. 5. A. G. Zatsepin, A. O. Korzh, V. V. Kremenetskii, et al., “Studies of the Hydrophysical Processes over the Shelf and Upper Part of the Continental Slope of the Black Sea with the Use of Traditional and New Observation OCEANOLOGY
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