Three-Dimensional Characterization of a Coastal Mode-Water Eddy from Multiplatform Observations and a Data Reconstruction Method

Abstract

Coastal mesoscale eddies are important oceanic structures partially responsible for regulating ocean-shelf exchanges. However, their description and characterization are challenging; observations are often too scarce for studying their physical properties and environmental impacts at the required spatio-temporal resolution. Therefore, models and data extrapolation methods are key tools for this purpose. Observations from high-frequency radar, one satellite and two gliders, are used here to better characterize the three-dimensional structure of a coastal mode-water eddy from a multiplatform approach in the southeastern Bay of Biscay in spring 2018. After the joint analysis of the observations, a three-dimensional data reconstruction method is applied to reconstruct the eddy current velocity field and estimate the associated water volume transport. The target eddy is detected by surface observations (high-frequency radar and satellite) for two weeks and presents similar dimensions and lifetimes as other eddies studied previously in the same location. However, this is the first time that the water column properties are also observed for this region, which depicts a mode-water eddy behavior, i.e., an uplift of the isopycnals in the near-surface and a downlift deeper in the water column. The reconstructed upper water column (1–100 m) eddy dynamics agree with the geostrophic dynamics observed by one of the gliders and result in cross-shelf inshore (offshore) volume transports between 0.04 (−0.01) and 0.15 (−0.11) Sv. The multiplatform data approach and the data reconstruction method are here highlighted as useful tools to characterize and three-dimensionally reconstruct coastal mesoscale processes in coastal areas.

Waves from compact SeaSonde® High Frequency radars in the southeastern Bay of Biscay: measurement performance under different noise and wind conditions

“…The network has provided surface current hourly data (with 3 hours rolling average) since 2009, with some interruptions mostly due to maintenance stops or malfunctioning related to severe atmospheric conditions. The performance of this network for ocean currents measurements and its potential for the study of ocean processes and transport patterns have already been demonstrated by previous works (e.g., Rubio et al, 2011;Solabarrieta et al, 2014;Solabarrieta et al, 2015;Solabarrieta et al, 2016;Manso-Narvarte et al, 2018;Rubio et al, 2018;Rubio et al, 2019;Manso-Narvarte et al, 2020;Rubio et al, 2020;Manso-Narvarte et al, 2021;Ruiz et al, 2022). However, wave information has so far remained unexploited.…”

“…BF is used by phased array radars while DF is mainly used by compact antennas. The EuskOOS SeaSonde ® compact HF radar (EuskOOS HF radar from now on) network has already been used to study surface coastal transport processes in the area in combination with multisource data (Rubio et al, 2011;Rubio et al, 2013;Solabarrieta et al, 2014;Solabarrieta et al, 2015;Solabarrieta et al, 2016;Manso-Narvarte et al, 2018;Rubio et al, 2018;Rubio et al, 2020;Manso-Narvarte et al, 2021). Besides measuring sea surface water velocity [Crombie (1955), Barrick et al, 1977, Paduan andRosenfeld (1996) and Paduan and Graber (1997)], the HF radar can also monitor waves (Lipa, 1978;Lipa and Barrick, 1982;Lipa and Nyden, 2005;Gurgel et al, 2006;Wyatt, 2011;Wyatt, 2021).…”

EuroGOOS roadmap for operational coastal downstream services

“…Several examples of such approaches can be found for instance in the case of the coastal HF radars (e.g. O'Donncha et al, 2014;Cianelli et al, 2015;Ren et al, 2015;Jordà et al, 2016, Manso-Narvarte et al, 2020, Manso-Narvarte et al, 2021. To obtain high-resolution subsurface current maps from the combination of HF radar data and other data sources in the water column is especially valuable for the development of services linked to biogeochemical and environmental issues, since plankton or pollutants can be located deeper in the water column and not only follow surface dynamics.…”

Temperature Structure Inversion of Mesoscale Eddies in the South China Sea Based on Deep Learning

“…The South China Sea is a vital marginal sea in the Pacific region, holding significant geographical importance. Mesoscale eddies, a common oceanic phenomenon, play a crucial role in heat transfer and nutrient transport in the South China Sea [1]. Typically, mesoscale eddies can survive for several days or even years, with spatial scales ranging from tens to hundreds of kilometers.…”