Analysis of the Black-Sea climatic fields below the main pycnocline obtained on the basis of assimilation of the archival data on temperature and salinity in the numerical hydrodynamic model

2009 ◽  
Vol 19 (1) ◽  
pp. 1-12 ◽  
Author(s):  
S. G. Demyshev ◽  
V. A. Ivanov ◽  
N. V. Markova
Keyword(s):  
Black Sea ◽  
Hydrodynamic Model ◽  
The Black Sea ◽  
Archival Data ◽  
Main Pycnocline

Water Masses in the Black Sea as Seen by Profiling Floats. A revisit of the role of winter, slope and geothermal convectio.

2021 ◽  
Author(s):  
Emil Stanev ◽  
Boriana Chtirkova ◽  
Elisaveta Peneva
Keyword(s):  
Black Sea ◽  
Intermediate Layer ◽  
Cold Water ◽  
Density Ratio ◽  
Water Masses ◽  
The Black Sea ◽  
Convective Layer ◽  
First Time ◽  
Main Pycnocline

<p>More than 6000 profiles from profiling floats in the Black Sea over the 2005-2020 period were used to study the ventilation of this basin from the top to the very bottom. In the upper layers and in the main pycnocline, water masses show a strong interannual variability following intermittent events of cold water formation. The density ratio decreased three times during the last 15 years, revealing the decreasing role of temperature in the vertical layering of the Black Sea halocline. The deep transition layer (DTL) between 700 and 1700 m acts as an interface between the baroclinic layer and the largest bottom convective layer (BCL) of the world oceans. On top of DTL are the warm intermediate layer (WIL) and deep cold intermediate layer (DCIL). They both showed strong trends in the last fifteen years due to warmer climate and intensification of warmer intrusions from Bosporus. A “salinity wave” was detected in 2005-2009 below ~1700 m, which evidenced for the first time the penetration of gravity flow from Bosporus down to the bottom. The layering of water masses was explained as resulting from the different distribution of sources of heat and salt, double duffusion and balances between the geothermal and salinity flows in the BCL.</p>

scholarly journals Simulation modelling of wind-induced sea level fluctuations at the ports of the Odesa Region in the North-Western part of the Black Sea

2019 ◽  
pp. 109-120
Author(s):  
Yu. S. Tuchkovenko
Keyword(s):  
Sea Level ◽  
Black Sea ◽  
Hydrodynamic Model ◽  
Temporal Variability ◽  
The Black Sea ◽  
Sea Level Fluctuations ◽  
The North ◽  
Allowable Error ◽  
Spatio Temporal ◽  
North Western

The paper is devoted to discussion of the prospects of simplified 2D hydrodynamic model use aimed at forecasting the wind-induced sea level fluctuations within the area of sea ports (Chornomorsk, Odesa and Yuzhnyi) of the Odesa Region in the North-Western part of the Black Sea. Spatio-temporal variability of wind conditions at the sea-atmosphere division is specified based on the data of the global numerical weather prediction model of the Global Forecast System (GFS). The research includes the description of the mathematical structure of the hydrodynamic model and the results of its adaptation to the conditions of the simulated sea area. It presents the results of model verification in the version which implies adoption of wind data from the archives of GFS-analysis and GFS-forecasts for 2010, 2016 and 2017. The verification was performed by comparing wind-induced denivellations of the sea level at the ports of Chornomorsk, Odesa and Yuzhnyi calculated over the course of modelling and those established on the basis of observational data (with the discreteness of 6 hours). A quantitative assessment of the calculation accuracy was performed for the cases where, according to the observational data, level denivellations exceeded the value of the standard deviation for the entire series. New series of the observed and calculated model-based significant wind-induced denivellations of sea level were formed for each of the ports from the sets of samples that met this condition. Using  these series estimates of the mean square error of the calculations, allowable error of calculations, correlation coefficient between the actual and calculated values of the level denivellations, the probability of the calculation method under the allowable error were obtained. It was established that in the case of use of the data from wind GFS-analysis (with spatial resolution of 0.5° both latitudinally and longitudinally) over the course of modelling the probability of calculation of significant sea level denivellation constitutes 84-85%, and in case of using the data from the GFS-archive of wind forecasts (with spatial resolution of 0.25°) – 88-91%. This allowed making a conclusion that the model has good prospects of use for operational forecast of the sea level fluctuations caused by storm wind in the version implying assimilation of the predicted information on the spatio-temporal variability of wind conditions obtained by means of the GFS global weather forecast model.

scholarly journals Decomposition of the time series of the pH values of the surface water of the deep Black Sea according to archival data of the second half of the XXth century

2021 ◽  
pp. 29-38
Author(s):  
E.A. Grebneva ◽  
◽  
A.B. Polonsky ◽  
Keyword(s):  
Time Series ◽  
Black Sea ◽  
Ph Value ◽  
Colorimetric Method ◽  
World Ocean ◽  
Atmospheric Precipitation ◽  
The Black Sea ◽  
Time Interval ◽  
Archival Data ◽  
Rate Of Increase

Based on the archival data of the Institute of Natural and Technical Systems for the period from 1956 to 1996 the decomposition of the time series of the pH value of the surface layer of the deep-water part of the Black Sea was carried out with subsequent extrapolation until 2010. The analysis shows that the reconstructed time series is divided into two time interval trends with different sign and data quality: from 1956 to 1976 and from 1977 to 1996. The presence of these two fundamentally different time periods is largely due to the method for determining the pH value. Until about the mid-1970s the pH value in the Black Sea was determined mainly by the colorimetric method with an accuracy of tenths of pH, i.e. with a high error. In subsequent years, the potentiometric method began to be widely used, the accuracy of which is an order of magnitude higher. Therefore, further in the work, the second time period is analyzed – since 1977. In the time course of pH, a regular seasonal variation, interannual quasicyclic components of variability with periods of about 6.7 and 2.5 years, and a significant negative linear trend are identified. It is most likely that the main reason for the quasiperiodic variability of pH in the upper layer of the open part of the Black Sea on an interannual scale is related to variations in atmospheric precipitation caused by changes in cyclonic activity in the Atlantic-European sector, including the Black Sea region, in different phases of climatic modes in the ocean-atmosphere system (such as, in particular, NAO). The highlighted tendency of the pH value since 1977 indicates the acidification of the upper layer of the Black Sea waters, with an average rate of about 0.013pH units / 10 years. This corresponds to the rate of increase in acidity of surface waters in other regions of the World Ocean. Expedition data from 2010 confirm the validity of the extrapolation performed.

Sign in / Sign up

Export Citation Format

Share Document