On the Seasonal Western Boundary Current System of the Weddell Gyre

• Main Authors: Pereira-Vázquez, Tania, Aguiar-González, Borja, Marrero-Díaz, Ángeles, Veny, Marta, Rodríguez-Santana, Ángel
• Format: Text
• Language: English
• Published: 2024
• Subjects: Bransfield Strait; Weddell; Weddell Sea; South Atlantic Ocean
• Online Access: https://doi.org/10.5194/egusphere-2024-1166; https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1166/

We investigate the seasonal Western Boundary Current System (WBCS) of the Weddell Sea Gyre using two open-access global ocean circulation reanalysis products (NEMO and HYCOM at different resolutions), direct velocity measurements and altimetry data across an extended version of the historical ADELIE transect, hereafter E-ADELIE. The NEMO-based products are GLORYS2V4 and GLORYS12V1, provided daily with 0.25º and 0.08° of horizontal resolution, respectively. The HYCOM-based product is GLBv0.08, provided daily with 0.08º of horizontal resolution between 40° S and 40° N, and 0.04º beyond these latitudes. The ADELIE extension is made to include a novel, persistent current, previously unreported, which we name as the Inner Weddell Current (IWC). With this approach, we aim to assess whether these open-access products capture properly the dynamics, natural mode of variability and spatio-temporal scales of the WBCS so that we can set the groundwork for future interannual variability studies. E-ADELIE is located at a key location of the WBCS, before it splits into different branches that redistribute Weddell Sea waters either leaving the basin towards Bransfield Strait, towards the South Atlantic Ocean, or recirculating within the gyre. The analyses include the characterization of the horizontal and vertical structure of the WBCS and its volume transport. Results show that both reanalysis products agree on key dynamics features only at high model resolutions; NEMO at the lower-resolution version lacks the typical multi-jet structure of the WBCS. The altimetry data is also in agreement in showing this year-round multi-jet structure but in winter, when data gaps prevent us from a comprehensive view. The cross-transect volume transport variability from the reanalysis products is consistent with the seasonality of the basin scale wind forcing in all model cases, with minimum values (25 ± 5 Sv) from September to December and maximum values (33 ± 5 Sv) ...