ISSN 0001 4338, Izvestiya, Atmospheric and Oceanic Physics, 2013, Vol 49, No 6, pp 674–685 © Pleiades Publishing, Ltd., 2013 Original Russian Text © A.A Kordzadze, D.I Demetrashvili, 2013, published in Izvestiya AN Fizika Atmosfery i Okeana, 2013, Vol 49, No 6, pp 733–745 Short Range Forecast of Hydrophysical Fields in the Eastern Part of the Black Sea1 A A Kordzadze and D I Demetrashvili Nodia Institute of Geophysics, Javakhishvili State University, ul M Alexidze 1, Tbilisi, 0171 Georgia e mails: akordzadze@yahoo.com, demetr_48@yahoo.com Received January 10, 2013; in final form, February 14, 2013 Abstract—On the basis of an analysis of the results of modeling and a forecast of the basic hydrophysical fields in the easternmost part of the Black Sea for 2010–2012, the features of annual variability of regional circu lating processes in this part of the sea basin are investigated A forecast of a hydrological mode is made on the basis of the regional forecasting system developed at the Institute of Geophysics at Javakhishvili State Uni versity in cooperation with the oceanographic centers of the Black Sea riparian countries within the frame work of the ARENA and ECOOP EU international scientific and technical projects The regional system is one of the components of the Black Sea basin scale Nowcasting/Forecasting System The analysis of the material cumulated for the registered period shows that the easternmost water area of the Black Sea is a dynamically active zone where there is a continuous formation of different circulating processes considerably distinguished from each other Keywords: numerical model, boundary conditions, system of hydrothermodynamics equations, flow field, vortex formation DOI: 10.1134/S0001433813060091 1 INTRODUCTION The study and forecast of hydro and thermody namic processes in the Black Sea is one of the basic questions of Black Sea oceanography The state of the sea ecosystem, distribution and transformation of dif ferent polluting substances, biochemical processes proceeding in the sea basin, etc., in many respects depend on spatial–temporal distribution of the hydro and thermodynamic characteristics of the sea (cur rent, temperature, salinity, and density) As the Black Sea and atmosphere create a uniform hydro and ther modynamic system, the sea dynamic processes sub stantially influence the distribution of the climatic characteristics in the Black Sea region as well [1, 2] Due to work performed within the framework of the ARENA and ECOOP EU international scientific and technical projects, we accumulated a significant volume of the results of modeling and day forecasts of dynamic processes for 2010–2012 in the eastern most part of the Black Sea An analysis of this material helps understand better the mechanisms of formation and evolution of hydro and thermodynamic processes in one of the dynamically active regions of the Black Sea and improve our knowledge about these processes The modeling and forecast of regional circulating processes is made on the basis of the regional forecast The article was translated by the autors ing system developed by us within the context of the abovementioned projects [3–5] This system is one of the components of the basin scale Black Sea Now casting/Forecasting System [6, 7] The core of the regional system is the regional model of the Black Sea dynamics of Nodia Institute of Geophysics (Tbilisi, Georgia) [4, 5], which further we will call RM–IG in the text It is nested in the basin scale Black Sea gen eral circulation model of the Marine Hydrophysical Institute of the National Academy of Sciences of Ukraine (MHI NASU, Sevastopol) The RM–IG is based on the basin scale model of the Black Sea dynamics [9], which is adapted to the eastern part of the sea basin with a simultaneous increase of horizon tal resolution from km up to km It is necessary to note that model [9] is an advanced version of model [10–14] The main goal of the present paper is to research the features of annual variability of regional dynamic processes for 2010–2012 REGIONAL FORECASTING SYSTEM The regional area of modeling and forecasting is limited to the Caucasian and Turkish coastal lines and the western liquid boundary coinciding approximately with the meridian 39.08° E and passing near the city of Tuapse (Fig 1) 674 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS 675 45 215 × 347 30 35 40 Fig Regional area of modeling and forecast ALADIN Model of atmosphere dynamics, Bucharest, Romania Model of Black Sea general circulation of MHI NASU, Sevastopol Upper boundary conditions Upper boundary conditions Initial and boundary conditions on liquid boundary Model outputs Regional model of Black Sea dynamics of Institute of Geophysics, Tbilisi, Georgia Forecasted flow, temperature and salinity fields for the easternmost part of the Black Sea with km spacing Fig Scheme of functioning of the regional forecasting system In Fig a schematic picture of the functioning of the regional forecasting system based on the RM–IG is shown All the required input data are provided from MHI NASU in operative mode via the ftp site The input data are as follows: 3D initial fields of the current velocity components, temperature, and salin ity; 2D fields of the same quantities on the liquid IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS boundary; and 2D meteorological fields at the sea sur face–heat fluxes, atmospheric precipitation, evapora tion, and wind stress The conditions on the liquid boundary are com puted prognostic values from the general circulation model of MHI NASU and the meteorological fields at the Vol 49 No 2013 676 KORDZADZE, DEMETRASHVILI upper boundary are prognostic fields calculated from the ALADIN regional atmospheric dynamics model [15] The RM–IG is based on a primitive system of ocean hydrothermodynamics equations, which is written in z coordinates for deviations of thermody namic values from the corresponding standard values The model takes into account the sea bottom relief, the configuration of the basin, atmospheric forcing, the river discharge of the Rioni and Inguri, the absorp tion of total solar radiation by the sea upper layer, and the spacial–temporal variability of factors of horizon tal and vertical turbulent viscosity and diffusion The factors of horizontal turbulent viscosity and diffusion are calculated during integration by the formula pro posed in [16] and the factors of vertical turbulent dif fusion are calculated by the formula presented in monograph [17] To solve the model equation system, the two cycle splitting method is used with respect to both physical processes, coordinate lines, and vertical planes; as a result, the solution to the basic problem is reduced to a solution of a set of relatively simple two dimensional and one dimensional problems [10, 14, 18] To approximate all spitted problems, a finite difference scheme is used; in addition, for an approximation of time, the Crank– Nicholson scheme As a whole, the scheme is energeti cally balanced, provides second order accuracy on time and space coordinates, and is absolutely steady VERIFICATION OF THE SEA DYNAMICS MODEL The functioning of the regional forecasting system was validated in 2005, when the pilot experiment on the functioning of the operative Nowcasting/Fore casting system of the state of the Black Sea with the participation of all Black Sea riparian countries within the framework of the ARENA project was carried out for the first time for the Black Sea region A compari son of results of the calculated forecasts with real data has shown the ability of the RM–IG to reliably predict hydrophysical fields in the Georgian coastal zone of the Black Sea [19] Currently we are able to carry out a comparison of the calculated sea surface temperatures with SST satellite images derived from NOAA (the Marine Portal site, NSAU, http://dvs.net.ua/mp) An analysis of the comparison shows good qualitative and quantitative agreement between the forecasted and measured temperature fields; in most points the error does not exceed 0.6–0.8°C [4] SIMULATION OF REGIONAL CIRCULATION PROCESSES The RM–IG uses a grid having 215 × 347 points with horizontal resolution km On the vertical, the nonuniform grid with 30 calculated levels on depths 2, 4, 6, 8, 12, 16, 26, 36, 56, 86, 136, 206, 306 to 2006 m are considered The time step is equal to 0.5 h Regular calculations of the regional forecasts for 2010–2012 show that the easternmost part of the Black Sea, including the Georgian water area, is a dynamically active zone Here, circulating processes are developed which are characterized by significant annual variability In Figs 3–6, the computed surface current fields from September 2011 to August 2012 are shown In addition three circulation patterns are selected for each month that are more characteristic for the corre sponding month 4.1 Autumn Circulation The main element of the September circulation in 2011 is the anticyclonic eddy with a diameter of about 100–120 km (the well known Batumi anticyclonic eddy), which was formed in the southwestern part of the considered area (Figs 3a–3c) The structure of this eddy undergoes some changes and, by the end of the month, substantially decreases in size Other than this vortex, it is possible to observe the formation of a second relatively smaller anticyclonic vortex starting mid September that is subject to certain changes Along the Caucasian coast, a narrow zone with a width of about 20–25 km is formed which is characterized by an intense form of small coastal unstable eddies, the existence of which is about 3–4 days The transforma tion of the circulating mode continues through Octo ber (Figs 3d–3f) By the end of October, the absence of the dominant direction and the presence of several small cyclonic and anticyclonic vortexes are charac teristic for the circulating pattern A similar circula tion pattern is maintained during November too, and here current speeds reach 65 cm/s (Figs 3g–3i) 4.2 Winter Circulation The circulating mode in December 2011 is charac terized mainly by the presence of a cascade of sharply expressed anticyclonic eddies (Figs 4a–4c) The Jan uary 2012 circulation in the first half of the month to a certain degree is similar to the December circulation, and the main elements of the circulating mode are obvi ously expressed cyclonic and anticyclonic eddies with the characteristic diameter approximately 30–40 km (Figs 4d–4f) The eastern branch of the Black Sea Rim Current is present in February circulation pat terns from the middle of the month, with maximal speeds of 60–70 cm/s at the core (Fig 4g–4i) In gen eral, the circulating mode in February 2012 is charac terized by weak vorticity, which can be explained by the strong atmospheric winds that develop during this period of the year Strong winds have a smoothing effect on the sea current and promote the disappear ance of vortical formations [9] IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS Vol 49 No 2013 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS N 44.0 43.5 (а) N 44.0 RM–IG 6.09.2011, 00:00 GMT z = m, Umax = 26 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (b) 43.5 Sukhumi 43.0 42.5 N 44.0 RM–IG 16.09.2011, 00:00 GMT z = m, Umax = 32 cm/s Sochi Gagra Trabzon Rize Batumi 41.5 41.0 39.5 40.0 40.5 41.0 41.5E N 44.0 43.5 RM–IG 7.10.2011, 00:00 GMT z = m, Umax = 35 cm/s Sochi Gagra 43.5 Sukhumi 43.0 Khopa Trabzon Rize 41.0 (e) Trabzon 41.0 43.5 (g) 43.5 Sukhumi 43.0 Khopa Trabzon Rize 41.0 (h) 42.0 Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E RM–IG 28.11.2011, 00:00 GMT z = m, Umax = 65 cm/s Sochi Gagra Sukhumi 42.5 Poti 42.0 Batumi Khopa (i) Poti 42.0 41.5 Trabzon 43.0 42.5 Poti 41.0 43.5 Sukhumi Khopa Rize 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 15.11.2011, 00:00 GMT z = m, Umax = 60 cm/s Sochi Gagra 43.0 42.5 Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 6.11.2011, 00:00 GMT z = m, Umax = 65 cm/s Sochi Gagra Poti Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 Sukhumi 42.0 Batumi Khopa (f) RM–IG 28.10.2011, 00:00 GMT z = m, Umax = 65 cm/s Sochi Gagra Poti 42.0 Rize Rize 42.5 Poti 41.5 Trabzon 43.0 42.5 42.0 41.0 43.5 Sukhumi Khopa 39.5 40.0 40.5 41.0 41.5E N 44.0 RM–IG 17.10.2011, 00:00 GMT z = m, Umax = 38 cm/s Sochi Gagra 43.0 42.5 Batumi 41.5 39.5 40.0 40.5 41.0 41.5E N 44.0 (d) Poti 42.0 Batumi 41.0 Sukhumi Poti 42.0 Khopa RM–IG 27.09.2011, 00:00 GMT z = m, Umax = 35 cm/s Sochi Gagra 42.5 Poti 41.5 (c) 43.0 42.5 42.0 677 Batumi 41.5 41.0 Khopa Trabzon Batumi 41.5 Khopa Rize 39.5 40.0 40.5 41.0 41.5 E 41.0 Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig Calculated surface current fields in autumn 2011 (a) September 6, (b) September 16, (c) September 27, (d) October 7, (e) October 17, (f) October 28, (g) November 6, (h) November 15, and (i) November 28 4.3 Spring Circulation The circulation mode of the first half of March 2012 was also characterized basically by vortex free motion (except for the formation some nearshore small vortexes), but by the end of the month the gen IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS eration of the anticyclonic vortex formation in the southwestern part of the considered area is observed (Figs 5a–5c) In April the anticyclonic vortex grows in size and is present throughout the month The nar row zone along the seashore is the zone of intense vor tex formation, where small coastal cyclonic and anti Vol 49 No 2013 678 KORDZADZE, DEMETRASHVILI N 44.0 43.5 (а) N 44.0 RM–IG 4.12.2011, 00:00 GMT z = m, Umax = 55 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (b) 43.5 Sukhumi 43.0 42.5 N 44.0 RM–IG 15.12.2011, 00:00 GMT z = m, Umax = 40 cm/s Sochi Gagra 42.5 42.5 42.0 Batumi 41.0 Khopa Trabzon Rize 41.0 43.5 (d) 43.5 Sukhumi 43.0 Khopa Trabzon Rize 41.0 (e) 43.5 Sukhumi 41.0 Trabzon 41.0 43.5 RM–IG 5.02.2012, 00:00 GMT z = m, Umax = 70 cm/s Sochi Gagra 43.5 Sukhumi 43.0 Khopa Trabzon Rize 43.5 Sukhumi Khopa Trabzon RM–IG 25.02.2012, 00:00 GMT z = m, Umax = 70 cm/s Sochi Gagra Sukhumi Poti 42.0 Batumi Batumi 41.5 41.0 39.5 40.0 40.5 41.0 41.5 E (i) 42.5 Batumi Rize Rize Poti 42.0 41.5 Trabzon 43.0 42.5 42.0 Khopa 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 14.02.2011, 00:00 GMT z = m, Umax = 60 cm/s Sochi Gagra Poti 41.0 41.0 (h) 43.0 42.5 Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 (g) Poti Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 Sukhumi 42.0 Batumi Khopa RM–IG 30.01.2012, 00:00 GMT z = m, Umax = 32 cm/s Sochi Gagra 42.5 42.0 Rize (f) Poti Poti 41.5 Trabzon 43.0 42.5 42.0 Khopa Rize 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 16.01.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra 43.0 42.5 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 5.01.2012, 00:00 GMT z = m, Umax = 45 cm/s Sochi Gagra Batumi Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 Poti Poti 42.0 41.5 Sukhumi 43.0 Poti 42.0 (c) RM–IG 28.12.2011, 00:00 GMT z = m, Umax = 40 cm/s Sochi Gagra Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E 41.5 41.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig Calculated surface current fields in winter (a) December 4, 2011; (b) December 15, 2011; (c) December 28, 2011; (d) January 5, 2012; (e) January 16, 2012; (f) January 30, 2012; (g) February 5, 2012; (h) February 14, 2012; and (i) February 25, 2012 Umax cyclonic eddies are generated and transformed (Figs 5d–5f) In the middle of May, the anticyclonic eddy amplifies, and, by the end, weakens The current speeds decrease 4.4 Summer Circulation At the beginning of the summer, the anticyclonic eddy is stretched along the meridian and, as a result, in mid June, two anticyclonic eddies are formed IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS Vol 49 No 2013 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS N 44.0 43.5 (а) N 44.0 RM–IG 3.03.2012, 00:00 GMT z = m, Umax = 60 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (b) 43.0 42.5 Poti 42.0 Khopa Trabzon Rize Batumi 41.0 43.5 (d) 43.0 Khopa Trabzon Rize 43.5 42.5 Trabzon Rize 41.0 43.5 (g) 43.5 Sukhumi 43.0 Khopa Trabzon Rize Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E 39.5 40.0 40.5 41.0 41.5 E RM–IG 30.05.2012, 00:00 GMT z = m, Umax = 26 cm/s Sochi Gagra 43.5 Sukhumi Sukhumi 43.0 42.5 Poti Poti 42.0 Batumi 41.0 Rize (i) 42.0 Khopa Trabzon N 44.0 RM–IG 20.05.2012, 00:00 GMT z = m, Umax = 22 cm/s Sochi Gagra Poti 41.5 Khopa 41.0 42.5 42.0 Batumi 41.5 (h) 43.0 42.5 Poti 42.0 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 8.05.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra Sukhumi Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 43.0 Poti 42.0 Khopa (f) RM–IG 27.04.2012, 00:00 GMT z = m, Umax = 35 cm/s Sochi Gagra 42.5 Batumi 41.0 43.5 Sukhumi Poti 41.5 Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 17.04.2012, 00:00 GMT z = m, Umax = 35 cm/s Sochi Gagra 42.5 42.0 Khopa 41.0 (e) 43.0 Sukhumi Batumi 41.5 39.5 40.0 40.5 41.0 41.5 E N 44.0 RM–IG 5.04.2012, 00:00 GMT z = m, Umax = 40 cm/s Sochi Gagra Poti 42.0 41.5 39.5 40.0 40.5 41.0 41.5E N 44.0 Sukhumi 42.5 Batumi 41.0 43.0 42.5 41.5 RM–IG 30.03.2012, 00:00 GMT z = m, Umax = 45 cm/s Sochi Gagra 43.5 Sukhumi Poti 42.0 (c) N 44.0 RM–IG 15.03.2012, 00:00 GMT z = m, Umax = 50 cm/s Sochi Gagra 679 41.0 Batumi Batumi 41.5 Khopa Trabzon Rize 41.5 Khopa 41.0 39.5 40.0 40.5 41.0 41.5 E Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig Calculated surface current fields in spring 2012 (a) March 3, (b) March 15, (c) March 30, (d) April 5, (e) April 17, (f) April 27, (g) May 8, (h) May 20, and (i) May 30 (Figs 6a–6c) In June a narrow zone of vortex forma tion along seashore is easily observed, too An anticy clonic vortex with a diameter of about 25–30 km in the area between Sukhumi and Poti is especially evident At the beginning of July, the formation of an anticy IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS clonic vortex in the northwestern part of the area under consideration is observed By the end of July this vortex extends in a southern direction (Figs 6d–6f) In August an anticyclonic vortex forms in the center of the area under consideration and then gradually Vol 49 No 2013 680 KORDZADZE, DEMETRASHVILI N 44.0 43.5 (а) N 44.0 RM–IG 6.06.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (b) N 44.0 43.5 Khopa Trabzon Rize 42.0 39.5 40.0 40.5 41.0 41.5 E (d) RM–IG 4.07.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra 43.5 Sukhumi 43.0 N 44.0 Khopa Trabzon Rize RM–IG 17.07.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra Poti Sukhumi 41.0 N 44.0 43.5 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E (g) RM–IG 6.08.2012, 00:00 GMT z = m, Umax = 26 cm/s Sochi Gagra 43.5 Sukhumi 43.0 Khopa Trabzon Rize RM–IG 15.08.2012, 00:00 GMT z = m, Umax = 24 cm/s Sochi Gagra Poti Sukhumi 41.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Poti Batumi N 44.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E (i) RM–IG 25.08.2012, 00:00 GMT z = m, Umax = 18 cm/s Sochi Gagra Sukhumi 43.0 Poti 42.0 Poti 42.0 Batumi 41.5 41.0 Sukhumi 42.5 Batumi 41.5 RM–IG 27.07.2012, 00:00 GMT z = m, Umax = 26 cm/s Sochi Gagra 41.5 43.5 42.5 42.0 39.5 40.0 40.5 41.0 41.5 E (f) 42.0 41.0 39.5 40.0 40.5 41.0 41.5 E (h) 43.0 42.5 Rize Batumi 41.5 N 44.0 Trabzon 43.0 Poti 42.0 41.0 N 44.0 Khopa 42.5 Batumi 41.5 Batumi 41.5 43.5 42.5 42.0 Poti 42.0 41.0 39.5 40.0 40.5 41.0 41.5 E (e) 43.0 42.5 Sukhumi Batumi 41.5 41.0 RM–IG 20.06.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra 42.5 Poti Batumi 41.5 (c) 43.0 42.5 Poti 42.0 41.0 43.5 Sukhumi 43.0 42.5 N 44.0 RM–IG 17.06.2012, 00:00 GMT z = m, Umax = 30 cm/s Sochi Gagra Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Batumi 41.5 41.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig Calculated surface current fields in summer 2012 (a) June 6, (b) June 17, (c) June 29, (d) July 4, (e) July 17, (f) July 27, (g) August 6, (h) August 15, and (i) August 25 extends and covers an area with a diameter of about 80–90 km (Figs 6g–6i) A data analysis of the circulating modes for 2010– 2012 shows that the circulation modes of the same sea son in the easternmost part of the Black Sea can siderably differ from each other in different years Apparently, this is promoted by different meteorologi cal regimes which are formed over the easternmost part of the Black Sea On confirmation of this fact is a comparison of summer circulation regimes in 2010 and 2012 (Figs 6, 7) Unlike summer circulation in 2012, summer circulation in 2010 (Fig 7) was charac terized by sharply distinguished features The main feature of the regional circulation in 2010 was the existence of the Batumi anticyclonic eddy practically throughout the summer It was a rather steady forma IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS Vol 49 No 2013 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS N 44.0 43.5 (а) N 44.0 RM–IG 4.07.2010, 00:00 GMT z = m, Umax = 35 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (b) 42.5 42.5 Poti 42.0 Batumi 41.0 Khopa Trabzon Rize 41.0 43.5 (d) 43.5 Sukhumi 43.0 42.5 Khopa Trabzon Rize (e) Trabzon Rize 39.5 40.0 40.5 41.0 41.5E RM–IG 25.08.2010, 00:00 GMT z = m, Umax = 26 cm/s Sochi Gagra Sukhumi 43.0 Poti Poti 42.0 Batumi 41.0 (f) 42.5 42.0 Khopa Rize 39.5 40.0 40.5 41.0 41.5E 43.5 Sukhumi Poti 41.5 Trabzon N 44.0 RM–IG 15.08.2010, 00:00 GMT z = m, Umax = 40 cm/s Sochi Gagra 43.0 Khopa 41.0 42.5 42.0 41.5 39.5 40.0 40.5 41.0 41.5E N 44.0 RM–IG 6.08.2010, 00:00 GMT z = m, Umax = 38 cm/s Sochi Gagra Batumi Batumi 41.5 39.5 40.0 40.5 41.0 41.5E N 44.0 Poti Poti 42.0 41.5 Sukhumi 43.0 42.5 42.0 RM–IG 27.07.2010, 00:00 GMT z = m, Umax = 34 cm/s Sochi Gagra 43.5 Sukhumi 43.0 (c) N 44.0 RM–IG 17.07.2010, 00:00 GMT z = m, Umax = 32 cm/s Sochi Gagra 681 41.0 Batumi Batumi 41.5 Khopa Trabzon Rize 41.5 Khopa 41.0 39.5 40.0 40.5 41.0 41.5E Trabzon Rize 39.5 40.0 40.5 41.0 41.5E Fig Calculated surface current fields in summer 2010 (a) July 4, (b) July 17, (c) July 27, (d) August 6, (e) August 15, and (f) August 25 tion which achieved maximal intensity in August and covered a significant part of the considered regional area It is interesting to note that, according to meteo rologists, summer 2010 was abnormally hot in Georgia relative to the last few decades The air temperature frequently reached and exceed 40°C, and coastal waters of the sea were heated up for more than 30°C The anomalous temperature regime obviously influ enced the mode of evaporation and precipitation, and, eventually, the thermohaline conditions of the sea coastal waters were favorable for the formation of an intense anticyclonic vortex An analysis of the satellite observations which have been carried out with the help of NOAA satellites has shown that the degree of cover age of the sky by clouds above the easternmost part of the Black Sea differed considerably in the summers of 2010 and 2012 The number of days when most of the considered territory was covered with clouds consider ably prevailed in the summer of 2012 This distinction was especially appreciable in August: In August 2012 IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS days with significant or strong cloudiness was about 65%, and in 2010 it was only 0.2% The cloudy cover, which is a major element of climatic system, essen tially influences the solar radiation flux and, conse quently, the quantity of radiation absorbed by the sea An analysis of the satellite images of the sea surface temperature really confirms the statement mentioned above According to the NOAA satellite data, the tem perature of surface waters in the easternmost part of the sea was, on average, much higher in summer 2010 than in summer 2012 Figure 8, where the satellite images of the easternmost part of the Black Sea corre sponding to August and 25 in 2010 and 2012 are pre sented, shows that, on August 6, 2010, in most of the considered area, the temperature of the surface waters was 30°С and above, whereas, on the same day in 2012, most of the part above the sea surface was cov ered with clouds The part of the sea surface accessible to satellite measurements was characterized by a tem perature not exceeding about 27°С (Fig 8b) On Vol 49 No 2013 682 KORDZADZE, DEMETRASHVILI (а) NOAA–15 Aug 6, 2010 13:57 GMT 25 20 °C Sea surface temperature Sea surface temperature °C (b) NOAA–15 Aug 6, 2010 13:06 GMT 25 20 15 40 40 (c) (d) 25 °C NOAA–15 Aug 25, 2010 13:01 GMT 20 Sea surface temperature Sea surface temperature °C NOAA–15 Aug 25, 2010 13:44 GMT 25 20 15 20 40 40 Fig Satellite images of the surface temperature of the easternmost part of the Black Sea: (a) August 6, 2010; (b) August 6, 2012; (c) August 25, 2010; and (d) August 25, 2012 August 25 in 2010 and 2012, the easternmost part was practically free from clouds and, on this day in 2010, surface waters in the largest part were heated up to 28– 29°С (Fig 8c); on August 25, 2012, the temperature, on average, did not surpass 26–27°С (Fig 8d) An analysis of 2010–2012 data shows that the dis tribution of the salinity field in the considered regional area was undergoing some annual changes The gen eral character of variability of the salinity field within year depends as on the annual change of the balance in the evaporation—precipitation system and river inflow, as well as on the circulating characteristics An analysis of our data confirms the known fact that the salinity field correlates well with the circulation field There is a general regularity that anticyclonic eddies promote the formation of waters with low salinity in their central part, but with cyclonic eddies it is the other way around The upward flows in the center of the cyclonic eddy promote more salty waters being carried from deep layers in the upper layers and the downward flows in the central part of the anticyclonic eddy transfer less salty water from the upper layers downwards Thus, the circulating mode to a greater IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS Vol 49 No 2013 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS (а) N 44.0 43.5 Sochi ‰ 18.70 RM–IG 17.07.2012, 00:00 GMT z = 10 m (b) N 44.0 ‰ 18.42 18.18 Gagra Sochi 43.5 RM–IG 6.08.2012, 00:00 GMT z = 10 m 18.60 18.42 18.18 Gagra 17.94 17.94 Sukhumi 43.0 17.79 Sukhumi 43.0 17.79 17.65 17.65 42.5 17.20 Poti 42.5 17.20 16.48 Poti Batumi Batumi 41.0 41.5 Rize 41.0 N N (c) ‰ 18.60 RM–IG 44.0 Sochi Trabzon 17.07.2010, 00:00 GMT z = 10 m (d) 44.0 18.42 18.18 Gagra Rize 39.5 40.0 40.5 41.0 41.5 E 39.5 40.0 40.5 41.0 41.5 E 43.5 Khopa Khopa Trabzon Sochi 43.5 ‰ 18.60 RM–IG 6.08.2010, 00:00 GMT z = 10 m 18.42 18.18 Gagra 17.94 17.94 Sukhumi 43.0 17.79 Sukhumi 43.0 17.79 17.65 17.65 42.5 17.20 Poti 17.20 42.5 16.48 16.48 42.0 Poti 42.0 Batumi 41.5 41.0 16.48 42.0 42.0 41.5 683 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Batumi 41.5 Khopa 41.0 Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig Calculated salinity fields (‰) on horizon z = 10 m (a) July 17, 2012; (b) August 6, 2012; (c) July 17, 2010; and (d) August 6, 2010 degree defines the structure of the salinity field in the easternmost regional area of the basin This fact is especially clearly seen by a comparison of salinity patterns corresponding to summer in 2010 and 2012, when the circulating modes sharply differed from each other From Fig 9, where the calculated salinity fields on horizon z = 10 m corresponding to summer 2010 and 2012 are shown, it is clearly visible that the intensive Batumi anticyclonic eddy observed in summer 2010 considerably affected the salinity regime in the easternmost part of the basin Here there was relatively low salinity in the significant central area of the vortex and the peripheral current of the vortex promoted the penetration of more salty waters from the open area of the sea into the easternmost water area Figure 10, where the distributions of surface tem perature for four season are shown, gives certain infor mation about the seasonal evolution of the tempera IZVESTIYA, ATMOSPHERIC AND OCEANIC PHYSICS ture field in the surface layer The temperature field undergoes both significant qualitative and quantitative seasonal change, and the character of its change in the surface layer is basically defined by heat exchange between the sea and atmosphere For the considered water area, to rather small spatial extent, large hori zontal gradients of the surface temperature field tem perature are not observed CONCLUSIONS In conclusion, when summarizing the studies of simulated hydrophysical fields for 2010–2012 carried out in the work, it is possible to briefly formulate the basic features of the annual variability of dynamic pro cesses in the eastern water area of the Black Sea Throughout the year, the continuous generation, deformation, and disappearance of the cyclonic and anticyclonic vortex formations occur in the eastern Vol 49 No 2013 684 KORDZADZE, DEMETRASHVILI N 44.0 43.5 (а) Autumn Sochi T, °C 22.0 RM–IG 17.10.2011, 00:00 GMT z=0m N 44.0 (b) Winter 21.5 21.0 Gagra 43.5 Sochi T, °C 10.2 RM–IG 17.01.2012, 00:00 GMT z=0m 10.0 Gagra 9.8 20.5 Sukhumi 43.0 20.0 9.6 Sukhumi 43.0 9.4 19.5 19.0 42.5 17.5 9.2 42.5 9.0 Poti Poti 42.0 42.0 Batumi Batumi 41.5 41.0 41.5 Khopa Trabzon Rize 41.0 43.5 (c) Spring RM–IG Sochi 17.04.2012, 00:00 GMT z=0m T, °C 12.2 Gagra 11.8 N 44.0 43.5 11.4 Sukhumi 43.0 Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E 39.5 40.0 40.5 41.0 41.5 E N 44.0 Khopa 11.0 (d) Summer T, °C RM–IG Sochi 19.07.2012, 00:00 GMT z=0m 27.0 Gagra 26.5 Sukhumi 43.0 26.25 10.6 10.2 42.5 26.0 25.5 42.5 25.0 9.8 Poti 42.0 Poti 42.0 Batumi Batumi 41.5 41.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E 27.5 41.5 41.0 Khopa Trabzon Rize 39.5 40.0 40.5 41.0 41.5 E Fig 10 Calculated surface temperature fields (°C) corresponding to different seasons 2011–2012 (a) October 17, 2011; (b) Jan uary 17, 2012; (c) April 17, 2012; and (d) July 19, 2012 most part of the sea In addition, an analysis of the computed fields again confirms the fact known from the literature [20] that the most intensive vortical for mation is the Batumi eddy of anticyclonic character, which exists in the warm period of the year In most cases, in the narrow zone along the Caucasian coast with a width of about 20–30 km, an area of intense vortex is formed where the generation of small unsta ble eddies with sizes from about to 25 km occurs It is necessary to note that such coastal small eddies are identified also in other coastal areas of the Black Sea [21, 22] Vortical formation weakens in February, when the atmospheric wind amplification has a smoothing action on the current sea In that case, when the Batumi eddy is intensive and occupies a sig nificant part of the considered water area, it forms a certain mode of salinity: the salinity of waters consid erably decreases in the central part of the vortex and the peripheral current of the Batumi eddy promotes the penetration of more salty waters from the open part of the Black Sea in the easternmost part REFERENCES V S Samoilenko, “Unity of the atmosphere and ocean,” Vestn Mosk Univ., Ser 5: Geogr., No 6, 20– 30 (1967) E V Solyankin, “The microclimatic role of the Black Sea,” Okeanologiya (2), 28–36 (1964) A Kordzadze and D Demetrashvili, “Some results of forecast of hydrodynamic processes in the easternmost part of the Black Sea,” J Georg Geophys Soc 14b, 37–52 (2010) A A Kordzadze and D 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nearshore regions,” in European Oper ational Oceanography: Present and Future, 4th EuroGOOS Conference, 6–9 June 2005, Brest, France, 2006, pp 605–610 G Korotaev, T Oguz, A Nikiforov, and C Koblinsky, “Seasonal, interannual, and mesoscale variability of the Black Sea upper layer circulation derived from altime ter data,” J Geophys Res 108 (C4), 3122 (2003) doi 10.1029/2002JC001508 V A Ivanov and Yu S Tuchkovenko, “Applied mathe matical modeling of water quality in sea shelf ecosys tems” (MHI, Sevastopol, 2006) [in Russian] S G Demyshev, “Numerical prognostic calculation of the Black Sea with high horizontal resolution,” Morsk Girofiz Zh., No 1, 36–47 (2011) Vol 49 No 2013 .. .SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS 675 45 215 × 347 30 35 40 Fig Regional area of modeling and forecast ALADIN Model of atmosphere dynamics, Bucharest, Romania Model of Black... Institute of Geophysics, Tbilisi, Georgia Forecasted flow, temperature and salinity fields for the easternmost part of the Black Sea with km spacing Fig Scheme of functioning of the regional forecasting... PHYSICS Vol 49 No 2013 SHORT RANGE FORECAST OF HYDROPHYSICAL FIELDS A A Kordzadze and D I Demetrashvili, “Regional operational system for predicting the state of the east ern part of the Black Sea,”