1. Context of the project

1.1 Objectives

The main goal of the OST-ST IMHOTEP project is to investigate the response of the global ocean to fully-varying freshwater discharges from rivers and from the Greenland ice sheet between 1980 and 2018. We are investigating this response in terms of sea surface salinity (SSS), regional sea surface height (SSH) and its manometric/steric components, heat and freshwater contents, water mass properties, regional to basin-scale circulation, etc. We are currently analyzing satellite/in-situ observations and the outputs from a recent series of NEMO-based global ocean/sea-ice/iceberg 1/4° simulations where runoffs are individually set to climatological OR fully-variable in various source regions.

Daily river discharge data are derived from the ISBA-CTRIP hydrological reanalysis (Decharme et al., 2019), and monthly (solid and liquid) freshwater discharges from Greenland are derived from satellite altimetry data (SAR mode) combined with regional climate simulations (Mouginot et al., 2019). Special attention was dedicated to the bathymetry and the partitioning between solid and liquid discharges all around Greenland, in order to realistically feed icebergs and freshwater plumes. The JRA55 fully-variable atmospheric forcing is applied in all simulations without any SSS relaxation, which is replaced by a precipitation correction term that lets surface tracers free to evolve.

On-going studies led by the projects partners (IGE, Datlas, LOPS, LEGOS) currently focus on the regional responses in the Arctic region, in the Bay of Bengal, in the Amazon outh, as well as on the global scale. See the reference section below to get the most recent abstracts submitted to conferences and papers related to the project. In particular, latest presentations about IMOTEP:

• 2022 Penduff, T., S. Leroux, W. Llovel, J.-M. Molines, J. Vialard, M. Lengaigne, S. Tajouri, F. Sevellec, J. Jouanno, F. Papa, C. de Boyer, 2022 : Toward a probabilistic assessment of the global ocean response to fully-varying river runoffs. Ocean Surface Topography Science Team (OST/ST) Meeting, October 31 November 4 2022, Venice, Italy. (Oral) DOI: 10.24400/527896/a03-2022.3553

• 2022 Llovel, W., S. Tajouri, F. Sevellec, T. Penduff, J.-M. Molines, S. Leroux, P. Mathiot, J. Mouginot, 2022 : Impact of Greenland freshwater discharge on regional sea level trends in the Arctic ocean. Ocean Surface Topography Science Team (OST/ST) Meeting, October 31 - November 4 2022, Venice, Italy. (Poster) DOI: 10.24400/527896/a03-2022.3550

1.2 Related references & publications:

Articles:

• 2023 Zhao, M., R. M. Ponte, and T. Penduff : Global-scale random bottom pressure fluctuations from oceanic intrinsic variability. Submitted to Science.

• 2021 Llovel W., N. Kolodziejczyk, S. Close, T. Penduff, J.-M. Molines and L. Terray, Imprint of intrinsic ocean variability on decadal trends of regional sea level and ocean heat content using synthetic profiles, Environ. Res. Lett. 17 044063. https://doi.org/10.1088/1748-9326/ac5f93

• 2021 Zhao, M., Ponte, R. M., Penduff, T., Close, S., Llovel, W., & Molines, J.-M. (2021). Imprints of ocean chaotic intrinsic variability on bottom pressure and implications for data and model analyses. Geophysical Research Letters, 48, e2021GL096341. https://doi.org/10.1029/2021GL096341.

Conferences:

• 2022 Penduff, T., S. Leroux, W. Llovel, J.-M. Molines, J. Vialard, M. Lengaigne, S. Tajouri, F. Sevellec, J. Jouanno, F. Papa, C. de Boyer, 2022 : Toward a probabilistic assessment of the global ocean response to fully-varying river runoffs. Ocean Surface Topography Science Team (OST/ST) Meeting, October 31 November 4 2022, Venice, Italy. (Oral) DOI: 10.24400/527896/a03-2022.3553

• 2022 Llovel, W., S. Tajouri, F. Sevellec, T. Penduff, J.-M. Molines, S. Leroux, P. Mathiot, J. Mouginot, 2022 : Impact of Greenland freshwater discharge on regional sea level trends in the Arctic ocean. Ocean Surface Topography Science Team (OST/ST) Meeting, October 31 - November 4 2022, Venice, Italy. (Poster) DOI: 10.24400/527896/a03-2022.3550

• 2022 Tajouri et al., Amazon river runoff contribution to regional ocean circulation changes over 1993-2015 in the Caribbean Sea, 20th DRAKKAR ocean modeling workshop 2022 (oral).

• 2022 Soumaïa Tajouri, William Llovel, Florian Sévellec, Thierry Penduff, Jean-Marc Molines, Stéphanie Leroux, Jérémie Mouginot. Impact of Greenland ice melting on sea level trend over 1998-2011 in the Arctic Ocean, WCRP Sea Level Conference, Singapore, July 2022 (Poster)

• 2022 Lucas Dassin, Virginie Thierry, William Llovel. North Atlantic ocean circulation changes due to interannual land freshwater discharge, 2022 Sea Level Workshop, June 2022 (poster)

• 2022 Soumaïa Tajouri, William Llovel, Florian Sévellec, Thierry Penduff, Jean-Marc Molines, Stéphanie Leroux, Jérémie Mouginot. Impact of Greenland ice melting on sea level trend over 1998-2011 in the Arctic Ocean, 2022 Sea Level Workshop, Brest, June 2022 (oral).

• 2022 Sally Close, Thierry Penduff, William Llovel, Alice Carret. Estimating the atmospherically-driven part of sea-level variability from observations, 2022 Sea Level Workshop, June 2022 (oral)

• 2022 Llovel W. et al. IMpacts of freshwater discHarge interannual variability on Ocean heaT-salt contents and rEgional sea level change over the altimetry Period : the IMHOTEP project, Ocean Science Meeting , Feb. 2022 (oral)

• 2022 Mengnan Zhao, Rui Ponte, Thierry Penduff, Sally Close, William Llovel and Jean-Marc Molines, Imprints of Ocean Chaotic Intrinsic Variability on Bottom Pressure and Implications for Data and Model Analyses, Ocean Science Meeting , Feb. 2022 (Oral) * 2022 Llovel W., Nicolas Kolodziejczyk, Sally Close, Thierry Penduff, Jean-Marc Molines, and Laurent Terray, Imprint of intrinsic ocean variability on ocean heat content and thermosteric sea level over 2005-2015, DRAKKAR workshop, Jan. 2022 (oral).

• 2022 Zhao, Mengnan; Ponte, Rui; Penduff, Thierry; Close, Sally; Llovel, William; Molines, Jean-Marc. Imprints of Ocean Chaotic Intrinsic Variability on Bottom Pressure and Implications for GRACE Data Interpretation and Dealiasing. GRACE/GRACEFO annual meeting, Oct 2021 (oral).