EGU2020-5689
https://doi.org/10.5194/egusphere-egu2020-5689
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Forced and chaotic variability of interannual variability of regional sea level and its causes scale over 1993-2015

Alice Carret1, William Llovel2, Thierry Penduff3, Jean-Marc Molines3, and Benoît Meyssignac1
Alice Carret et al.
  • 1CNRS/LEGOS, Toulouse, France
  • 2Ifremer/LOPS, Plouzané, France
  • 3CNRS/IGE, Grenoble, France

Since the early 1990s, satellite altimetry has become the main observing system for continuously measuring the sea level variations with a near global coverage. Satellite altimetry has revealed a global mean sea level rise of 3.3 mm/yr since 1993 with large regional sea level variability that differs from the mean estimate. These measurements highlight complex structures especially for the western boundary currents or the Antarctic Circumpolar Current. A recent study shows that the chaotic ocean variability may mask atmospherically-forced regional sea level trends over 38% of the global ocean area from 1993 to 2015. The chaotic variability is large for the western boundary currents and in the Southern Ocean. The present study aims to complement this previous work in focusing on the interannual variability of regional sea level. A global ¼° ocean/sea-ice 50-member ensemble simulation is considered to disentangle the imprints of the atmospheric forcing and the chaotic ocean variability on the interannual variability of regional sea level over 1993-2015. We investigate the forced (i.e., ensemble mean) versus the chaotic variability (i.e., ensemble standard deviation) for the interannual variability of regional sea level and its causes (i.e., steric sea level and manometric sea level contribution). We complement our investigations by partitioning the steric component into thermosteric sea level (i.e., temperature change only) and halosteric sea level (i.e., salinity change only). One of the goals of the study is to highlight the hot spots region of large chaotic variability for regional sea level and its different components.

How to cite: Carret, A., Llovel, W., Penduff, T., Molines, J.-M., and Meyssignac, B.: Forced and chaotic variability of interannual variability of regional sea level and its causes scale over 1993-2015, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5689, https://doi.org/10.5194/egusphere-egu2020-5689, 2020

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Display material version 2 – uploaded on 06 May 2020
I updated a legend, a logo and the title of the presentation to shorten it.
  • CC1: Physical interpretation of the manometric sea level, Robin Waldman, 06 May 2020

    Bonjour Alice,

    I came too late for the live chat on your presentation, but I wanted to ask you about the physical interpretation of the manometric sea level. If I understand it well it is just the residual between the total sea level anomaly and that due to the density anomaly profile. How do you interpret its physical origin and its large value near the coast?

    Thanks!

    Robin

    • AC1: Reply to CC1, Alice Carret, 06 May 2020

      Hi Robin,

      no the manometric sea level is not a residual, we computed it. Near the coast, the depth is shallower so the atmospheric forcings are mainly barotropic which lead to large values concerning the manometric sea level. There is also an increase of surface pressure near the coasts due to higher greenhouse gases concentrations.

      I hope it answer to your question.

      Alice

      • CC2: Reply to AC1, Robin Waldman, 06 May 2020

        Thank you very much. I had read in the Penduff et al 2019 that it was deduced as the difference between the total and steric sea level anomaly. How do you compute this term then? Thank you!

        • AC2: Reply to CC2, Alice Carret, 07 May 2020

          Actually, you were right it is the residual between the total sea level anomaly and the steric sea level anomaly (0-6000m). Sorry, I didn't do it and sometimes we use the formula : pb - Δpa)/(ρg).

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