Untangling spatial and temporal trends in the variability of the Black Sea Cold Intermediate Layer and mixed Layer Depth using the DIVA detrending procedure

2014 ◽  
Vol 64 (3) ◽  
pp. 315-324 ◽  
Author(s):  
A. Capet ◽  
C. Troupin ◽  
J. Carstensen ◽  
M. Grégoire ◽  
J.-M. Beckers
2020 ◽  
Vol 27 (5) ◽  
Author(s):  
P. N. Lishaev ◽  
V. V. Knysh ◽  
G. K. Korotaev ◽  
◽  
◽  
...  

Purpose. The investigation is aimed at increasing accuracy of the temperature field reconstruction in the Black Sea upper layer. For this purpose, satellite observations of the sea surface temperature and the three-dimensional fields of temperature (in the 50–500 m layer) and salinity (in the 2.5–500 m layer) pseudo-measurements, previously calculated by the altimetry and the Argo floats data, were jointly assimilated in the Marine Hydrophysical Institute model. Methods and Results. Assimilation of the sea surface temperature satellite observations is the most effective instrument in case the discrepancies between the sea surface and the model temperatures are extrapolated over the upper mixed layer depth up to its lower boundary. Having been analyzed, the temperature profiles resulted from the forecast calculation for 2012 and from the Argo float measurements made it possible to obtain a simple criterion (bound to the model grid) for determining the upper mixed layer depth, namely the horizon on which the temperature gradient was less or equal to ≤ 0.017 °C/m. Within the upper mixed layer depth, the nudging procedure of satellite temperature measurements with the selected relaxation factor and the measurement errors taken into account was used in the heat transfer equation. The temperature and salinity pseudo-measurements were assimilated in the model by the previously proposed adaptive statistics method. To test the results of the sea surface temperature assimilation, the Black Sea hydrophysical fields were reanalyzed for 2012. The winter-spring period (January – April, December) is characterized by the high upper mixed layer depths, well reproducible by the Pacanowski – Philander parameterization, and also by the low values (as compared to the measured ones) of the basin-averaged monthly mean square deviations of the simulated temperature fields. The increased mean square deviations in July – September are explained by absence of the upper mixed layer in the temperature profiles measured by the Argo floats that is not reproduced by the Pacanowski – Philander parameterization. Conclusions. The algorithm for assimilating the sea surface temperature together with the profiles of the temperature and salinity pseudo-measurements reconstructed from the altimetry data was realized. Application of the upper mixed layer depths estimated by the temperature vertical profiles made it possible to correct effectively the model temperature by the satellite-derived sea surface temperature, especially for a winter-spring period. It permitted to reconstruct the temperature fields in the sea upper layer for 2012 with acceptable accuracy.


2019 ◽  
Vol 35 (5) ◽  
Author(s):  
A. A. Kubryakov ◽  
V. N. Belokopytov ◽  
A. G. Zatsepin ◽  
S. V. Stanichny ◽  
V. B. Piotukh ◽  
...  

2020 ◽  
Vol 36 (5) ◽  
Author(s):  
P. N. Lishaev ◽  
V. V. Knysh ◽  
G. K. Korotaev ◽  
◽  
◽  
...  

Purpose. The investigation is aimed at increasing accuracy of the temperature field reconstruction in the Black Sea upper layer. For this purpose, satellite observations of the sea surface temperature and the three-dimensional fields of temperature (in the 50–500 m layer) and salinity (in the 2.5–500 m layer) pseudo-measurements, previously calculated by the altimetry and the Argo floats data, were jointly assimilated in the Marine Hydrophysical Institute model. Methods and Results. Assimilation of the sea surface temperature satellite observations is the most effective instrument in case the discrepancies between the sea surface and the model temperatures are extrapolated over the upper mixed layer depth up to its lower boundary. Having been analyzed, the temperature profiles resulted from the forecast calculation for 2012 and from the Argo float measurements made it possible to obtain a simple criterion (bound to the model grid) for determining the upper mixed layer depth, namely the horizon on which the temperature gradient was less or equal to 0.017°C/m. Within the upper mixed layer depth, the nudging procedure of satellite temperature measurements with the selected relaxation factor and the measurement errors taken into account was used in the heat transfer equation. The temperature and salinity pseudo-measurements were assimilated in the model by the previously proposed adaptive statistics method. To test the results of the sea surface temperature assimilation, the Black Sea hydrophysical fields were reanalyzed for 2012. The winterspring period (January – April, December) is characterized by the high upper mixed layer depths, well reproducible by the Pacanowsci – Philander parameterization, and also by the low values (as compared to the measured ones) of the basin-averaged monthly mean square deviations of the simulated temperature fields. The increased mean square deviations in July – September are explained by absence of the upper mixed layer in the temperature profiles measured by the Argo floats that is not reproduced by the Pacanowsci – Philander parameterization. Conclusions. The algorithm for assimilating the sea surface temperature together with the profiles of the temperature and salinity pseudo-measurements reconstructed from the altimetry data was realized. Application of the upper mixed layer depths estimated by the temperature vertical profiles made it possible to correct effectively the model temperature by the satellite-derived sea surface temperature, especially for a winter-spring period. It permitted to reconstruct the temperature fields in the sea upper layer for 2012 with acceptable accuracy.


2019 ◽  
Vol 26 (5) ◽  
Author(s):  
A. A. Kubryakov ◽  
V. N. Belokopytov ◽  
A. G. Zatsepin ◽  
S. V. Stanichny ◽  
V. B. Piotukh ◽  
...  

2018 ◽  
Vol 167 ◽  
pp. 11-23 ◽  
Author(s):  
S. Miladinova ◽  
A. Stips ◽  
E. Garcia-Gorriz ◽  
D. Macias Moy

2021 ◽  
Vol 28 (4) ◽  
Author(s):  
A. N. Morozov ◽  
E. V. Mankovskaya ◽  
◽  

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.


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