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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Ocean Observation
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1456205
This article is part of the Research Topic Demonstrating Observation Impacts for the Ocean and Coupled Prediction View all 14 articles

Assimilation of Synthetic and Real SWOT Observations for the North Atlantic Ocean and Canadian East Coast using the Regional Ice Ocean Prediction System

Provisionally accepted
Guoqiang Liu Guoqiang Liu 1*Gregory C. Smith Gregory C. Smith 2A.-A. Gauthier A.-A. Gauthier 3C. Hébert-Pinard C. Hébert-Pinard 2Will Perrie Will Perrie 1
  • 1 Bedford Institute of Oceanography (BIO), Dartmouth, Canada
  • 2 Meteorological Research Division, Environment and Climate Change Canada (ECCC), Dorval, Canada
  • 3 Meteorological Service of Canada, Environment and Climate Change Canada (ECCC), Dorval, Canada

The final, formatted version of the article will be published soon.

    The Surface Water Ocean Topography (SWOT) mission significantly improves on the capabilities of current nadir altimeters by enabling two-dimensional mapping. Assimilating this advanced data into high-resolution models poses challenges. To address this, Observing System Simulation Experiments (OSSEs) were conducted to evaluate the effects of both simulated and actual SWOT data on the Regional Ice Ocean Prediction System (RIOPS). This study examines the OSSEs' design, focusing on the simulated observations and assimilation systems used. The validity of the OSSE designs is confirmed by ensuring the deviations between the assimilation system and the Nature Run (NR) align with discrepancies observed between actual oceanic data and OSSE simulations. The study measures the impact of assimilating SWOT and two nadir altimeters by calculating root mean square forecast error for sea surface height (SSH), temperature, and velocities, along with performing wave-number spectra and coherence analyses of SSH errors. The inclusion of SWOT data is found to reduce RMS SSH errors by 16% and RMS velocity errors by 6% in OSSEs. The SSH error spectrum shows that the most notable improvements are for scales associated with the largest errors in the range of 200-400 km, with a 33% reduction compared to traditional data assimilation. Additionally, spectral coherence analysis shows that the limit of constrained scales is reduced from 280 km for conventional observations to 195 km when SWOT is assimilated as well. This study also represents our first attempt at assimilating early-release SWOT data. A set of Observing System (data denial) experiments using early-release SWOT measurements shows similar (but smaller) responses to OSSE experiments in a two nadir-altimeter context. In a six-altimeter constellation setup, a positive impact of SWOT is also noted, but of significantly diminished amplitude. These findings robustly advocate for the integration of SWOT observations into RIOPS and similar ocean analysis and forecasting frameworks.

    Keywords: SWOT, North Atlantic modeling, data assimilation, OSSE experiments, Ocean dynamic

    Received: 28 Jun 2024; Accepted: 10 Oct 2024.

    Copyright: © 2024 Liu, Smith, Gauthier, Hébert-Pinard and Perrie. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Guoqiang Liu, Bedford Institute of Oceanography (BIO), Dartmouth, Canada

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.