EGU2020-594
https://doi.org/10.5194/egusphere-egu2020-594
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Variations of oceanic and atmospheric heat fluxes in the North Atlantic and their link to the North Atlantic Oscillation Index

Diana Iakovleva1 and Igor Bashmachnikov1,2
Diana Iakovleva and Igor Bashmachnikov
  • 1Saint Petersburg state University, Institute of Earth sciences, Oceanology, Saint-Petersburg, Russian Federation (dianayak47@mail.ru)
  • 2Nansen International Environmental and Remote Sensing Centre, Saint Petersburg, Russian Federation

Interannual variations in the upper ocean heat and freshwater contents in the subpolar North Atlantic has important climatic effect. It affects the intensity of deep convection, which, in turn, forms the link between upper and deep ocean circulation of the global ocean Conveyor Belt.

The upper ocean heat content is primarily affected by two main process: by the ocean-atmosphere heat exchange and by oceanic heat advection. The intensity of both fluxes in the subpolar gyre is linked to the character of atmospheric circulation, largely determined by the phase of the North Atlantic Oscillation (NAO).

To study the interannual variability of the oceanic heat advection (in the upper 500th meters layer) we compare the results from four different data-sets: ARMOR-3D (1993-2018), SODA3.4.2 and SODA3.12.2 (1980-2017), and ORAS5 (1958-2017). The ocean-atmosphere heat exchange is accessed as the sum of the latent and the sensible heat fluxes, obtained from OAFlux data-set (1958-2016).

The oceanic heat advection to the Labrador and to the Irminger seas has high negative correlation (-0.79) with that into the Nordic Seas. During the years with high winter NAO Index (NAOI) the oceanic heat advection into the Subpolar Gyre decreases, while to the Nordic Seas – increases. These variations go in parallel with the intensification of the Norwegian, the West Spitsbergen and the slope East Greenland currents and weakening of the West Greenland and the Irminger Currents. During the years with high NAOI, the ocean heat release (both sensible and latent) over the Labrador and Irminger seas increases, but over the Norwegian Sea it decreases.

In summary, the results show that, during the positive NAO phase, the observed decrease of the heat content in the upper Labrador and Irminger seas is linked to both, a higher oceanic het release and a lower intensity of advection of warm water from the south. In the Norwegian Sea, the opposite sign of variations of the fluxes above leads to a simultaneous warming of the upper ocean.

The investigation is supported by the Russian Scientific Foundation (RSF), number of project 17-17-01151.

 

 

How to cite: Iakovleva, D. and Bashmachnikov, I.: Variations of oceanic and atmospheric heat fluxes in the North Atlantic and their link to the North Atlantic Oscillation Index, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-594, https://doi.org/10.5194/egusphere-egu2020-594, 2019

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Display material version 1 – uploaded on 02 May 2020
  • CC1: Comment on EGU2020-594, Laura Jackson, 05 May 2020

    Thanks - thought this was some interesting analysis. I think it would also be interesting to repeat the analysis but with multi-year means. This is because the ocean often integrates the effect of the NAO and there may be some lag for the currents to respond. It would be good to know whether you get the same or different results from doing this.

    Laura

    • AC1: Reply to CC1, Diana Iakovleva, 06 May 2020

      Laura, thank you for your comment. I'll think about it.