Deep Penetrating Cooling in the Black Sea as a Reaction to Cold Air Intrusions in Winter

Cover Page

Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription or Fee Access

Abstract

We study the reaction of the Black Sea upper layer, and in particular the cold intermediate layer (CIL), to intense wind forcing during cold air intrusions (CAIs) in winter. Using atmospheric reanalysis ERA5 and marine reanalysis Copernicus, we obtained joint distributions of surface wind speed and water temperature differences at various depths for the period of 2000–2020. It is shown that reaction time of the sea upper layer to such extreme weather event as CAI is about 2 days. Also, it is shown that CAI influence extends to great depths, up to 60–70 m. Using coupled mesoscale sea-atmosphere model, we investigated the cooling mechanisms of the sea upper layer during the CAI case in January, 23–25, 2010. Two sensitivity experiments with suppressed air-sea interaction were performed. In the first experiment, sensible and latent heat fluxes from the sea surface were switched off. In the second experiment, wind shear stress at the sea surface was switched off. It is shown that the main reason for temperature decrease in the upper mixed layer was sea surface cooling due to sensible and latent heat fluxes. And the mechanism of deep cooling, that penetrates to the pycnocline, was vertical turbulent mixing caused by wind waves breaking and shear instability. In the first experiment, temperature decrease was insignificant; it was caused mainly by the entrainment of cold water from the CIL through the lower boundary of the mixed layer. In the second experiment, temperature decrease was as significant as in the control run. It is shown that after switching off wind shear stress in the second experiment turbulent mixing in the upper quasi-homogeneous layer of the sea changed fundamentally. In order to compensate the decrease of turbulence intensity and provide the same vertical heat flux as in the control run, the spatial vertical scale of turbulent eddies increased.

Full Text

Restricted Access

About the authors

V. V. Efimov

Marine Hydrophysical Institute of the RAS

Email: darik777@mhi-ras.ru
Russian Federation, 2, Kapitanskaya St., Sevastopol, 299011

D. A. Yarovaya

Marine Hydrophysical Institute of the RAS

Author for correspondence.
Email: darik777@mhi-ras.ru
Russian Federation, 2, Kapitanskaya St., Sevastopol, 299011

O. I. Komarovskaya

Marine Hydrophysical Institute of the RAS

Email: darik777@mhi-ras.ru
Russian Federation, 2, Kapitanskaya St., Sevastopol, 299011

References

  1. Баянкина Т.М., Сизов А.А., Юровский А.В. О роли холодных вторжений в формировании аномалии зимней поверхностной температуры Черного моря // Процессы в геосредах. 2017. № 3. С. 565–572.
  2. Ефимов В.В., Яровая Д.А. Численное моделирование конвекции в атмосфере при вторжении холодного воздуха над Черным морем // Изв. РАН. Физика атмосферы и океана. 2014. Т. 50, № 6. С. 692–703. doi: 10.7868/S0002351514060078
  3. Ефимов В.В., Яровая Д.А. Численное моделирование реакции Черного моря на вторжение аномально холодного воздуха 23–25 января 2010 года // Морской гидрофизический журнал. 2024. Т. 40. № 1. С. 130–145.
  4. Зацепин А.Г. и др. Формирование прибрежного течения в Черном море из-за пространственно-неоднородного ветрового воздействия на верхний квазиоднородный слой // Океанология. 2008. Т. 48. № 2. С. 176–192.
  5. Коротаев Г.К., Кныш В.В., Кубряков А.И. Исследование процессов формирования холодного промежуточного слоя по результатам реанализа гидрофизических полей Черного моря за 1971–1993 гг. // Известия РАН. Физика атмосферы и океана. 2014. Т. 50. № 1. С. 41–56. doi: 10.7868/S0002351513060102
  6. Куклев С.Б., Зацепин А.Г., Подымов О.И. Формирование холодного промежуточного слоя в шельфово-склоновой зоне северо-восточной части Черного моря // Океанологические исследования. 2019. Т. 47. № 3. С. 58–71. doi: 10.29006/1564–2291.JOR–2019.47(3).5
  7. Овчинников И.М., Попов Ю.И. Формирование холодного промежуточного слоя в Черном море // Океанология. 1987. Т. 27. № 5. С. 739–746.
  8. Пиотух В.Б., Зацепин А.Г., Казьмин А.С., Якубенко В.Г. Реакция термохалинных характеристик деятельного слоя Черного моря на зимнее выхолаживание // Океанология. 2011. Т. 51, № 2. С. 232–241.
  9. Сизов А.А., Баянкина Т.М. Особенность формирования температуры верхнего слоя Чёрного моря во время холодного вторжения // Доклады академии наук. 2019. Т. 487. № 4. С. 443–447.
  10. Яровая Д.А., Ефимов В.В. Воздействие Новороссийской боры на верхний слой Черного моря // Метеорология и гидрология. 2024 (в печати).
  11. Canuto V.M., Cheng Y., Dubovikov M.S. Ocean Turbulence. Part I: One-Point Closure Model − Momentum and Heat Vertical Diffusivities // Journal of Physical Oceanography, 2001, V. 31, 1413−1426.
  12. Hong S.-Y., Noh W.G., Dudhia J.A. A new vertical diffusion package with an explicit treatment of entrainment processes// Mon. Wea. Rev. 2006. V. 134. P. 2318 – 2341.
  13. Madec G. et al. NEMO ocean engine // Notes du Pole de Modelisation 27, Inst. Pierre-Simon Laplace, Paris, France. 2008.
  14. Miladinova S., Stips A., Garcia-Gorriz E., Macías D. Formation and changes of the black sea cold intermediate layer // Progress in Oceanography. 2018. V. 167. P. 11–23. doi: 10.1016/j.pocean.2018.07.002
  15. Reffray G., Bourdalle-Badie R., Calone C. Modelling turbulent vertical mixing sensitivity using a 1-D version of NEMO // Geosci. Model Dev. 2015. V. 8. P. 69–86.
  16. Samson G. et al. The NOW regional coupled model: Application to the tropical Indian Ocean climate and tropical cyclone activity // Journal of Advances in Modeling Earth Systems. 2014. V. 6. P. 1–23.
  17. Skamarock W.C. et al. A description of the Advanced Research WRF version 3 // NCAR Technical Note. 2008.
  18. Stanev E.V., Peneva E., Chtirkova B. Climate change and regional ocean water mass disappearance: case of the Black Sea // Journal of Geophysical Research: Oceans. 2019. V. 124, iss. 7. P. 4803–4819. doi: 10.1029/2019JC015076
  19. Valcke S. The OASIS3 coupler: a European climate modelling community software // Geosci. Model Dev. 2013. V. 6, iss. 2. P. 373–388.
  20. Umlauf L., Burchard H. A generic length-scale equation for geophysical turbulence models // Journal of Marine Research, 2003, 61, 235–265.
  21. https://resources.marine.copernicus.eu/product-detail/GLOBAL_MULTIYEAR_PHY_001_030/INFORMATION

Supplementary files

Supplementary Files
Action
1. JATS XML
Download
2. Fig. 1. Sea temperature change (°С) at a depth of 30 m during the CCS on 23-25 January 2010 from data of the Copernicus reanalysis. The point (32°E; 44.5°N) is marked, for which Figs. 4-7.

Download (426KB)
Indexing metadata
3. Fig. 2. Joint distribution of water temperature change ∆T(t) = T(t) - T(t - 2) and drive wind speed V(t), where t is time in days, at depths of (a) 0.5 m, (b) 47 m at (32°E; 44°N).

Download (291KB)
Indexing metadata
4. Fig. 3. Joint distribution of total sea surface heat flux (W/m2) at point (31°E; 45°N) and drive wind speed (m/s) at point (31°E; 46.7°N).

Download (127KB)
Indexing metadata
5. Fig. 4. Variation of the upper sea surface temperature (°C) during the cold intrusion on 23-25 January 2010 at (32°E; 44.5°N) for (a) the main calculation, (b) experiment 1, and (c) experiment 2. The upper part of the figure shows the sea surface friction stress (N/m2; black line) and the total heat flux (W/m2; red line).

Download (577KB)
Indexing metadata
6. Fig. 5. Variation of vertical temperature profiles (°C) during the cold intrusion on 23-25 January 2010 at (32°E; 44.5°N) for (a) the main calculation, (b) experiment 1, (c) experiment 2.

Download (192KB)
Indexing metadata
7. Fig. 6. Variation of the vertical momentum exchange coefficient (m2/s) during the cold intrusion on 23-25 January 2010 at (32°E; 44.5°N) for (a) main calculation, (b) experiment 1, (c) experiment 2.

Download (493KB)
Indexing metadata
8. Fig. 7. Vertical profiles of a) exchange coefficient (m2/s), b) TKE (m2/s2), and c) mixing path (m) at (32°E; 44.5°N) at 12 h on 23 January 2010 for the main calculation, experiment 1, and experiment 2. For clarity, in Fig. 7b, the TKE value for experiment 2 is increased by a factor of 10.

Download (334KB)
Indexing metadata

Copyright (c) 2024 Russian Academy of Sciences

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.