Spatial Characteristics of the Black Sea Cold Intermediate Layer in Summer, 2017

Purpose. The aim of the paper is to study spatial characteristics of the cold intermediate layer (CIL) after its waters were renewed due to the cold winter, using analysis of the data obtained during the Black Sea expedition in June 14 – July 3, 2017 (the 95th cruise of R/V “Professor Vodyanitsky”). Methods and Results. The data both from the CTD-measurements by the SBE911+ probe and the current velocity profile measurements by the Lowered Acoustic Doppler Current Profiler (LADCP) were used. Isopycnic averaging of the profile ensembles was applied to obtain the averaged characteristics of the water vertical thermohaline structure. During the measurement period, the minimum average temperature of the CIL core was 7.2°C at the density value 14.5 kg/m3. The layer upper boundary (according to the 8°C criterion) corresponded to the density value ~14.3 kg/m3, its lower one – to ~15.0 kg/m3. CIL water formation was most pronounced in the vicinity of the Rim Current, which was clearly seen on the isopycnic surfaces 14.6, and 15.0 kg/m3. According to the measurements, the main mass of CIL waters was identified in the Rim Current and in its right part (on the coast side). The CIL maximum thickness was ~60 m and the vertical position of its core corresponded to the 40–100 m depth. Conclusions. The synchronous profiles of current velocity, temperature, salinity, and density obtained in the Black Sea expedition in summer, 2017 made it possible to analyze the waters thermohaline structure with the regard for real dynamic situation. As a result, the CIL parameters, its spatial scales and position relative to the Rim Current were determined with due regard for the features of the density field structure in summer, 2017. This information can be useful for model verification and numerical experiments aimed at studying the mechanisms and the areas of CIL formation in the Black Sea.

Spatial Characteristics of the Black Sea Cold Intermediate Layer in Summer, 2017

Purpose. The aim of the paper is to study spatial characteristics of the cold intermediate layer (CIL) after its waters were renewed due to the cold winter, using analysis of the data obtained during the Black Sea expedition in June 14 – July 3, 2017 (the 95th cruise of R/V “Professor Vodyanitsky”). Methods and Results. The data both from the CTD-measurements by the SBE911+ probe and the current velocity profile measurements by the Lowered Acoustic Doppler Current Profiler (LADCP) were used. Isopycnic averaging of the profile ensembles was applied to obtain the averaged characteristics of the water vertical thermohaline structure. During the measurement period, the minimum average temperature of the CIL core was 7.2°C at the density value 14.5 kg/m3 . The layer upper boundary (according to the 8°C criterion) corresponded to the density value 14.3 kg/m3 , its lower one – to 15.0 kg/m3 . CIL water formation was most pronounced in the vicinity of the Rim Current, which was clearly seen on the isopycnic surfaces 14.6, and 15.0 kg/m3 . According to the measurements, the main mass of CIL waters was identified in the Rim Current and in its right part (on the coast side). The CIL maximum thickness was 60 m and the vertical position of its core corresponded to the 40–100 m depth. Conclusions. The synchronous profiles of current velocity, temperature, salinity, and density obtained in the Black Sea expedition in summer, 2017 made it possible to analyze the waters thermohaline structure with the regard for real dynamic situation. As a result, the CIL parameters, its spatial scales and position relative to the Rim Current were determined with due regard for the features of the density field structure in summer, 2017. This information can be useful for model verification and numerical experiments aimed at studying the mechanisms and the areas of CIL formation in the Black Sea

A climate index for the Newfoundland and Labrador shelf

This study presents in detail a new climate index for the Newfoundland and Labrador (NL) shelf. The NL climate index (NLCI) aims to describe the environmental conditions on the NL shelf and in the Northwest Atlantic as a whole. It consists of the average of 10 normalized anomalies, or subindices, derived annually: winter North Atlantic Oscillation, air temperature, sea ice season severity, iceberg count, seasonal sea surface temperature, vertically averaged temperature and salinity at the Atlantic Zone Monitoring Program (AZMP) Station 27, summer cold intermediate layer (CIL) core temperature at AZMP Station 27, summer CIL area on three AZMP hydrographic sections, and bottom temperature on the NL shelf. This index runs from 1951 to 2020 and will be updated annually. It provides continuity in the production of advice for fisheries management and ecosystem status on the NL shelf, for which a similar but recently abandoned index was used. The new climate index and its subindices are available at https://doi.org/10.20383/101.0301 (Cyr and Galbraith, 2020).

A climate index for the Newfoundland and Labrador shelf

This study presents in detail a new climate index for the Newfoundland and Labrador (NL) shelf. The NL climate index aims to describe the environmental conditions on the NL shelf and in the Northwest Atlantic as a whole. It consists of annual normalized anomalies of 10 subindices with equal contribution: Winter North Atlantic Oscillation, air temperature, sea ice season severity, iceberg count, sea surface temperature, vertically-averaged temperature and salinity at the Atlantic Zone Monitoring Program (AZMP) Station 27, cold intermediate layer (CIL) core temperature at AZMP Station 27, CIL area on 3 AZMP hydrographic sections and bottom temperature on the NL shelf. This index runs from 1951 to 2019, is open-access, and will be updated annually. This index and the subindices are available at https://doi.org/10.20383/101.0301 (Cyr and Galbraith, 2020).

FORMATION OF THE COLD INTERMEDIATE LAYER IN THE SHELF-SLOPE NORTHEASTERN PART ZONE OF THE BLACK SEA

The paper presents an overview of the existing hypotheses about the formation areas and the distribution mechanisms of the cold intermediate layer (CIL) in the Black Sea. The testing of the statistical hypothesis about the relationship of the CIL parameters in the shelf-slope zone of the Black Sea Northeastern part with the temperature of the atmosphere surface layer in the central part of the eastern cyclonic gyre is performed. The obtained high values of the correlation coefficients (~0.98) confirmed the dependence of the CIL parameters during its formation period from the air temperature over the Northeastern part of the Black Sea. One of the concepts of the “convective-advective” hypothesis by Ovchinnikov and Popov (1987) about approximately 2 months time shift between the processes of cold air masses invasion into the water area of the Black Sea and the developed CIL waters appearance in the coastal zone of the Gelendzhik area is also confirmed.