| 24 Feb 2026
Impact of wind variations on surface variability over the Patagonian Continental Shelves
Abstract. We study the impact of wind variability on sea surface temperature (SSTa), sea surface salinity (SSSa), and sea level anomaly (SLAa) over the Patagonian shelves around southern South America using satellite observations and the ERA5 reanalysis. Using Empirical Orthogonal Function (EOF) analysis, we identify the dominant patterns of variability in surface ocean properties and winds and assess their interconnections through correlation and composite maps. Zonal and meridional wind anomalies modulate the variability of sea level anomaly with distinct spatial signatures. Meridional wind variability emerges as the dominant driver, exerting a strong influence on sea surface temperature, salinity, and sea level, generating coherent patterns across the southeast South Pacific and southwest South Atlantic continental shelves. Specifically, the leading mode of meridional wind is significantly correlated with the dominant modes of variability of SSTa, SSSa, and SLAa. Moreover, the spatial patterns emerging from the composites associated with the leading meridional wind mode are consistent with the dominant SSTa, SSSa, and SLAa variability patterns. These results suggest that southerly winds promote upwelling and offshore flow of low salinity waters over the Pacific shelf, weaken the southward flowing Cape Horn Current along the shelf break, and strengthen the northward transport of cold-salty subantarctic water over the Atlantic shelf. Northerly winds reverse these dynamics. This study provides evidence of wind-driven coupling of the shelf circulation on both sides of South America and the interocean exchanges between the Pacific and Atlantic continental shelves.
This manuscript presents a comprehensive and well-structured analysis of the impact of wind variability on surface ocean properties over the Patagonian continental shelves. The study addresses a relevant and timely topic, combining satellite observations and reanalysis data with a coherent methodological framework based on EOF analysis, spectral decomposition, and composite techniques. The results are internally consistent and provide a physically plausible interpretation of the link between wind variability and ocean surface response. In particular, the identification of the dominant role of meridional wind variability and its connection to large-scale patterns across both the Pacific and Atlantic shelves is an interesting and valuable contribution.
The figures are clear, well organized, and effectively support the results presented in the manuscript. The captions are detailed and informative.
Overall, the manuscript is clearly written and well organized, and it makes a solid contribution to the understanding of regional ocean dynamics. The following comments are intended to further improve clarity, consistency, and the physical interpretation of some aspects of the analysis.
Introduction
The introduction is well structured and the progression from the general context to the regional description and study objectives is clear. However, the use of subheadings within the introduction feels somewhat inconsistent. The subheadings (“The Pacific Patagonian Shelf” and “The Atlantic Patagonian Shelf”) appear mid-introduction without corresponding subheadings for the opening paragraphs or the closing section on objectives, which may interrupt the overall flow.
This is also slightly inconsistent with the structure adopted in later sections of the manuscript (e.g., Methods and Results), where a clear hierarchical organization with numbered subsections is used. A simple way to improve this would be to introduce a third subheading (e.g., “Aims of this study”) to clearly mark the transition to the objectives and maintain structural consistency throughout the manuscript. In this context, it may also be helpful to move lines 115–119 (where the proposed mechanism is introduced) to the beginning of this subsection, as they would provide a more natural motivation for the objectives.
Additionally, the first two paragraphs (L28–37) would benefit from the inclusion of references. In particular, a general reference supporting the role of wind forcing on continental shelf dynamics (L31), as well as citations supporting the statements regarding previous studies and remaining knowledge gaps (L34 and L36–37), would strengthen the context and better position the study within the existing literature.
Results
Section 3.1
This section provides a useful and clear overview of the mean fields and variability patterns, effectively preparing the reader for the EOF analysis.
SSS variability (around line 263):
The discussion of nearshore SSS variability could benefit from a clearer distinction between physically meaningful variability and potential artefacts or uncertainties associated with satellite-derived salinity products in coastal regions. In this context, it may also be useful to explicitly acknowledge that satellite-derived salinity products can present systematic uncertainties near the coast and in regions with strong gradients, which could influence the interpretation of the spatial variability patterns.
SLA variability (around line 293):
The persistence of the spatial structure of SLA variability after removing the seasonal cycle is an interesting result. Since this is later explained in terms of intraseasonal wind forcing and geostrophic adjustment (Sections 3.3 and 4), a brief forward reference here, for example, noting that non-seasonal wind variability is explored in subsequent sections, would help the reader anticipate the physical interpretation and improve the flow of the manuscript.
Wind (around line 295) :
The relatively large variability of the meridional wind component compared to its mean—implying frequent reversals—is an important result. Since meridional wind variability is later identified as a key driver of ocean variability, it would be helpful to more explicitly highlight its physical implications here and briefly anticipate its role in modulating cross-shelf transport and surface properties.
Section 3.2.1 (EOF analysis)
The EOF analysis is well implemented and provides a useful framework to describe the dominant patterns of variability. Some aspects of the interpretation could be further refined. In particular, it would be useful to acknowledge that EOF modes represent statistical modes and are not necessarily associated with independent dynamical processes, especially when assigning physical meaning to them. Additionally, some modes (e.g., SSSa) explain a relatively small fraction of the total variance, their robustness and physical relevance could be further discussed. Also, a clearer connection between the spatial patterns and the dominant temporal scales identified in the spectral analysis would strengthen the interpretation.
In addition, it may be helpful to briefly discuss the sensitivity of the identified modes to the preprocessing choices (e.g., filtering and detrending), as these steps can influence the variance distribution and spatial patterns. Clarifying this would help assess the robustness of the EOF-based interpretation.
It may also be useful to briefly discuss the sensitivity of the results to the temporal filtering applied, as this could influence the variability patterns identified.
Section 3.3.2 (Composites)
This section provides a coherent and well-structured analysis linking wind variability to ocean surface properties through composite patterns. The results are internally consistent and physically plausible. However, some aspects of the interpretation could be slightly tempered. In particular, it would be helpful to more clearly distinguish between statistical consistency and physical causality when attributing changes to wind forcing.
Discussion (Section 4)
For consistency with the structure used in previous sections, it may be helpful to introduce subsection numbering in Section 4 (e.g., 4.1, 4.2, etc.), rather than using only informal subheadings.
SSSa: The discussion of SSSa variability is generally cautious but could be further refined. In particular, the leading EOF modes explain a relatively small fraction of the total variance, and the correlations with wind are relatively weak, suggesting a more complex and possibly multi-factorial control. Additional processes such as mixing, advection, and freshwater inputs may also play a role and could be more explicitly considered. Furthermore, the known limitations of satellite-derived salinity products, especially in coastal regions, should be more clearly taken into account when interpreting these patterns.