Preprints
https://doi.org/10.5194/egusphere-2022-702
https://doi.org/10.5194/egusphere-2022-702
10 Aug 2022
 | 10 Aug 2022

The signature of NAO and EA climate patterns on the vertical structure of the Canary Current Upwelling System

Tina Georg, Maria Conceição Neves, and Paulo Relvas

Abstract. The current study aims to analyse the vertical structure of the ocean during upwelling events using in situ and modelled data. Additionally, the influence of climate patterns, namely the North Atlantic Oscillation (NAO) and the East Atlantic (EA) pattern, on the vertical structure and their impact on the upwelling activity is assessed for a period of 25 years (1993–2017). The study focuses on the central part of the Canary Current (25–35° N) with persistent upwelling throughout the year with an annual cycle and strongest events from June to September.

Upwelling is determined using three different approaches: One index is calculated based on temperature differences between the coastal and the offshore area and two based on wind data and the resulting Ekman transport. Different data sets were chosen according to the indices.

Stable coastal upwelling can be observed in the study area for the analysed time span with differences throughout the latitudes and a time lag of four to five months between the wind and the temperature-based indices. A deepening of the isothermal layer depth and a cooling of temperatures is observed in the vertical structure of coastal waters representing a deeper mixing of the ocean and the rise of cooler, denser water towards the surface.

During years of a positive NAO, corresponding to a strengthening of the Azores High and the Iceland Low, stronger winds lead to an intensification of the upwelling activity, an enhanced mixing of the upper ocean and a deeper (shallower) isothermal layer along the coast (offshore). The opposite is observed in years of negative NAO. Both effects are enhanced in years with a coupled, opposite phase of the EA pattern and are mainly visible during winter months where the effect of both indices is the greatest. The study therefore suggests stronger upwelling activities in winters of positive North Atlantic Oscillation coupled with a negative East Atlantic pattern and emphasizes the importance of interactions between the climate patterns and upwelling.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.

Journal article(s) based on this preprint

30 Mar 2023
The signature of NAO and EA climate patterns on the vertical structure of the Canary Current upwelling system
Tina Georg, Maria C. Neves, and Paulo Relvas
Ocean Sci., 19, 351–361, https://doi.org/10.5194/os-19-351-2023,https://doi.org/10.5194/os-19-351-2023, 2023
Short summary
Tina Georg, Maria Conceição Neves, and Paulo Relvas

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-702', Anonymous Referee #1, 11 Nov 2022
    • AC1: 'Reply on RC1', Tina Georg, 11 Dec 2022
  • RC2: 'Comment on egusphere-2022-702', Anonymous Referee #2, 13 Nov 2022
    • AC2: 'Reply on RC2', Tina Georg, 11 Dec 2022
      • EC1: 'Reply on AC2', Andrew Moore, 11 Dec 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-702', Anonymous Referee #1, 11 Nov 2022
    • AC1: 'Reply on RC1', Tina Georg, 11 Dec 2022
  • RC2: 'Comment on egusphere-2022-702', Anonymous Referee #2, 13 Nov 2022
    • AC2: 'Reply on RC2', Tina Georg, 11 Dec 2022
      • EC1: 'Reply on AC2', Andrew Moore, 11 Dec 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Tina Georg on behalf of the Authors (08 Jan 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (11 Jan 2023) by Andrew Moore
RR by Anonymous Referee #2 (06 Feb 2023)
RR by Anonymous Referee #1 (07 Feb 2023)
ED: Publish subject to technical corrections (14 Feb 2023) by Andrew Moore
AR by Tina Georg on behalf of the Authors (15 Feb 2023)  Manuscript 

Journal article(s) based on this preprint

30 Mar 2023
The signature of NAO and EA climate patterns on the vertical structure of the Canary Current upwelling system
Tina Georg, Maria C. Neves, and Paulo Relvas
Ocean Sci., 19, 351–361, https://doi.org/10.5194/os-19-351-2023,https://doi.org/10.5194/os-19-351-2023, 2023
Short summary
Tina Georg, Maria Conceição Neves, and Paulo Relvas
Tina Georg, Maria Conceição Neves, and Paulo Relvas

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Short summary
This study aims to analyse the changes of the vertical structure of the ocean during upwelling and the role of climate patterns in the Canary Current (25–35° N) for a period of 25 years (1993–2017). Ocean mixing is enhanced during upwelling events and extents deeper (shallower) in the winters of positive (negative) North Atlantic Oscillation. It is enhanced during coupled, opposite phases of the East Atlantic pattern suggesting stronger upwelling activity in dependence of climate patterns.