Researches Of The Variability Of Some Factors,
RESEARCHES OF THE VARIABILITY OF SOME FACTORS,
WHICH DEFINE THE ECOLOGICAL STATE
OF THE NORTHWEST PART OF THE BLACK SEA
O.R. Andrianova, M.I. Skipa
Hydroacoustic Branch of the Marine Hydrophysical Institute
NAS of Ukraine, Odessa
Today, when the natural resources of Ukraine as well as many other regions of the World are exhausted or are fouled, the question of ecologically balanced steady development of economy of the state is actual. In this article we have made the attempt to explain the main principles of the informational system, which is permitting to model the development of the hydrophysical processes in the shore area of the Black Sea. The developed system will allow reaching the complete control of the development of the processes in this region. It is suggested to use the accumulated data banks on the hydrochemical, hydrophysical and dynamic characteristics as the main information. The simulation model of the development of the hydrodynamic processes in different layers of a near-shore area of the North-West part of the Black sea will be designed on the basis of this analysis. This model will take into account as stationary values the factors of effect - orographic features of the coast, bottom configuration, and variable factors – a thermohaline structure of waters, a field of oxygen, a river effluent, baroclinity, wind mode, anthropogenous effect etc.
The obtaining of the information about the temporary variability of the main characteristics is one of the aspects of the development of this system. In particular, we will stop on the analysis of the thermohaline structure and the field of oxygen of the North-West part of the Black sea. Data of immediate observations on the Black Sea are accumulated enough for an estimation of seasonal and interannual variability of the thermohaline characteristics in this region, the determination of the features of their vertical allocation, the definition of the periods of the main energetic oscillations of the investigated parameters. The processes happening in an ecosystem of the Black sea during spring - summer-autumn, in many aspects are determined by the features of
interaction of an atmosphere and sea in winter period, and then by selective accumulation of the energy in the central areas of the Black sea /1/, that’s why the temporary changes of the depth of the minimum temperature of water were analyzed. The subsequent reallocation of the energy forms the heat’s streams and biogenic’s streams from the deep-water layers to other parts of the sea, in particular, in the North-West shelf zone of the sea /2/.
We have selected the point on two sections for the analysis by latitude 43°40\’ N and by longitude 31°00\’ E, which were fulfilled multiply during 1970-1994 by different expeditions and then the estimations of the space-temporary variability of the temperature and salinity of water in the North-West part of the Black sea were conducted for them. The points were selected with the registration of a bottom configuration and a hydrodynamic process that\’s why the sections were crossed a shelf zone, continental slope and deep-water part of the sea.
On the preliminary estimation of the long-period variability of the thermohaline characteristics and the fields of oxygen on separate points in an active layer of waters of the Western part of the Black sea for 1970-1994 are selected 2-3 and 4-5 (6)-year oscillations. It is possible to mark that the selected trends determine the main prognostic tendencies and it are the descending or bottom-up branches of the long-period oscillations.
It is to research character and intensity of hydrodynamic processes in the Western part of the Black sea indirectly on a spatial distribution of the depth of the minimum temperature of water /3/. The position of this parameter corresponds to vertical allocation of the thermohaline characteristics: the depth of the minimum temperature of water in a continental slope region is magnified, and to the center of the cyclone circulation is slowly moderated. A winter convection in this circulation, and then the descending density currents are the main sources of the addition and the refreshing of waters of a cold intermediate layer (CIL) /1/.
The graphics of the annual changes for six points were calculated for the analysis of seasonal variability of minimum temperature of water, its depths, and also salinity, appropriate to it. We will begin Considering of the seasonal features of the change of the thermohaline characteristics and the position of the center of CIL from winter period, when the maximum of the cooling of the surface water and the refreshing of waters of the cold intermediate layer happens. During the cooling maximum in the region of the North-West shelf there occurs a universal convection and there is the formation of the cold waters, which are marked by low temperature and some low salinity. Cooling is so intensive, that the layer with minimum temperature of water is on the surface. The layer with the minimum temperature of water is on the surface too in the central part of the sea on the point 43°40\’ N 32°00\’ E, but the salinity and temperature of these waters is some what higher than shelf water. In spring the downwelling of the layer with the minimum temperature and the averaging of the thermohaline characteristics is watched on all researched points. Let\’s mark, that in the North-West part of the Black sea in warm period of the year the salinity of the upwelling cold bottom waters on a shelf corresponds to the salinity of waters CIL of the open sea. It testifies the output on the shelf of the CIL waters. However, in the spring season the upwelling of the CIL water on a shelf and the output them to shores are hampered because this region is under effect of the river streams and presence of the cold fresh waters. Thus, along the border of an extensive northwest shelf the interaction of the cold fresh waters (the winter formation) and waters of the open sea is observed. In summer the layer of winter cold waters becomes less. By autumn the cold fresh water disappears completely on a shelf, and the cold waters with salinity more than 18 ‰ (which forms in central parts) are saved only.
The estimation of the periodicity and detection of cycles in the temporary changes were conducted on the autocorrelation functions and spectral concentration for data on six points located on latitude and longitude sections. The calculations were fulfilled in such a manner that the annual wave was blanked at processing the data by annual average. On all graphs of spectral concentration quasi two- and three-year oscillations are brightly expressed, and so are the waves, which have periods, approximately equal to five and seven years. This fact will be matched with the results of the analysis of the interannual variability of the thermohaline characteristics, which were obtained by us, and also with the known literary data on other parameters. The long-period wave oscillations have found the reflection only on the some occasion. So, in particular, on an autocorrelation function on some points the oscillations with period 11-12 years are clearly visible. Besides, the cycles on 17-20 years are tracked.
The results, obtained in the investigation, can be used for the estimation of the possible oscillations of hydrodynamic parameters for the nearest perspective, and also at calculation of the long periodical forecast of their changes in the active layer of waters in the Western part of the Black Sea.
References
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2. Ovchinnikov I.M., Vinogradov M.E. Winter researches of an ecosystem of the Black Sea. Oceanology. 1991, v.30, No 6, pp. 1081-1085.
3. Andrianova O.R., Ovchinnikov I.M. The features of the transformation of the fresh waters in the western part of the Black Sea. Meteorology and hydrology. 1991. No 7, pp. 74-79.
4. Belevich R.R., Orlova I.G. The features of the interannual variability of the hydrological-hydrochemical characteristics of water on the North-West shelf of the Black Sea per the last decades 60-90-е years. Marine hydrohys. journal 1996. No 2, pp. 62-73.
5. Hydrometeorology and hydrochemistry of the seas USSR. V.IV. The Black Sea. No1. Meteorological conditions. S.-Pb. Hydrometeoizdat. 1991. 430p.
6. Ovchinnikov I.M., Osadchiy A.S. The century variability of the climatic conditions which defining the feature of the hydrological regime of the Black Sea. – The variability of an ecosystem of the Black Sea: the natural and anthropogenous factors. M. Science. 1991, pp. 85-89.
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