Estimation of the long-term variability of hydrophysical characteristics of the Black Sea based on the assimilation of the climatic hydrological fields L and altimetry data

Abstract

551.465To study the long-term variability of the thermohaline and dynamic characteristics of the Black Sea, we use three versions of climatic fields, namely, the fields reconstructed in the model according to the old (1903-1982) and new (1903-2003) hydrological climatic data arrays of temperature and salinity and according to the data of satellite altimetry. The analysis of the altimetry-based climatic fields confirms the distinctions (established earlier according to the old and new data arrays) in the seasonal variability of the integral characteristics of temperature and salinity and in the structures of hydrophysical fields in the sea. It is shown that, in the winter-spring season, the thermohaline fields reconstructed according to the new and altimetry data arrays are characterized by a small elevation of the halocline (pycnocline) and the upper boundary of the cold intermediate layer. In all seasons, the altimetry-based surface geostrophic currents contain numerous mesoscale eddies with different signs of rotation. Moreover, in all seasons, the Rim Current reconstructed according to the altimetry data is characterized by a narrower jet almost along the entire its length. This jet is especially intense near the coasts of West Anatolia.

Decadal variability of characteristics of the Black Sea pycnocline and geostrophic circulation in the wintertime

“…The circulation modeling performed using assimilation of climatic hydrological fields reconstructed from the modern dataset of 1903-2003 allowed revealing slight rise of the principal pycnocline in the winter-spring period (about 5 m) and MBSC intensification compared with the data of 1903-1982 [12,16].…”

Kinematic structure and mesoscale variability of the rim current near the coast of Crimea (according to the data of instrumental measurements in September 2008)

“…At present, there are numerous works devoted to the long-term and seasonal variations of the dynamics of its waters (see, e.g., [5][6][7][8][9][10][11][12][13]). It is shown that the eddy wave processes on synoptic scales (with typical sizes from ten to several tens kilometers and time scales from weeks to months) are observed in the upper 100-m layer in all seasons and characterized by significant space-and-time intermittence [6,[8][9][10]13].…”

Assimilation of climatic data in a model of circulation of waters in the Black Sea with regard for the space and time behavior of the variances and cross-covariance functions of forecast errors

“…In addition to the available arrays of climatic data on the temperature and salinity of waters in the Black Sea [1], we can mention the appearance of a new climatic database of monthly average fields of dynamic sea level [2]. These fields and the corresponding fields of temperature and salinity were obtained as a result of the assimilation of the data of altimetry measurements for 1992-2003 in the model [3].…”

“…In [2], it is shown that, parallel with the climatic thermohaline fields, the climatic altimetry fields also contain the data on the long-term variations of hydrophysical characteristics of the Black Sea. This is why a procedure of joint assimilation of the climatic hydrological temperature and salinity fields and the fields of climatic altimetry level in a dynamic model of the sea was proposed in [4].…”

“…are the monthly average arrays of climatic dynamic sea level, temperature, and salinity computed according to the results of assimilation of the altimetry data in the model; more detailed information these data can be found in [2]; ζ A ( x, y, t ) is the climatic altimetry sea level used for the assimilation in the model of circulation of waters; the procedure of its evaluation in the numerical model in each time step is presented in the next section;…”