the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 May 2026
The Mediterranean observation systems: MonGOOS analysis of present capabilities, weaknesses and perspectives
Abstract. Ocean monitoring is a crucial component of Earth's observation systems. These systems have evolved to achieve a global scope and an exceptionally high level of complexity, encompassing not only observation programs but also data centres for collection and storage, as well as computational facilities where predictions and re-analyses of oceanic conditions are generated using coupled ocean-atmosphere circulation models. The products generated by the different components of the oceanic observation systems are of paramount importance for the knowledge of the environmental state of the oceans, their variability ranges, the impact of natural and anthropogenic stressors (such as climate change) and, in summary, the appropriate governance of the sea and the sustainable use of its resources.
Given the diverse nature of the data (collected through a wide range of technologies, instruments, and institutions across multiple countries), it can be challenging to maintain a comprehensive overview of existing observation programs and datasets. MonGOOS (Mediterranean Oceanographic Network for the Global Ocean Observing System) serves as a GOOS (Global Ocean Observing System) Regional Alliance (GRA). Through its Observations Working Group (OBSWG), MonGOOS has conducted an extensive consultation among Mediterranean institutions to compile information on ongoing observation programs and the institutions operating within this basin. The results of this consultation, obtained through the collaboration of a very large number of scientists and technicians from a wide range of institutions, are reflected in this community report. These objectives of this report are:
i) To update our knowledge of existing observation capabilities in the Mediterranean Sea. ii) To identify contact persons for strengthening the current MonGOOS network in order to keep this information up to date in the future. iii) To describe the present strengths and weaknesses of the Mediterranean Sea’s observation system. iv) To support European ocean observation programs such as the Copernicus Marine Service and the European Marine Observation and Data Network (EMODnet).
The consultation phase began in July 2023 and continued until December 2025. It included a survey addressed to 90 researchers from 59 institutions across 18 countries as well as contacts with several EuroGOOS task teams, IOC (Intergovernmental Oceanographic Commission) sea level monitoring, as well as OceanOPS, for the compilation of metadata. During this consultation phase, the list of researchers addressed increased to 126. Finally, metadata from observation activities were obtained from 74 institutions belonging to 16 countries, 4 companies and the European Joint Research Centre (JRC).
The description of all the observation capabilities in the Mediterranean Sea is not closed and should be considered as an ongoing effort to be reviewed periodically and more systematically in the future. However, we believe that this objective has been accomplished to a high degree of detail and inclusivity. The present compilation includes most of the currently active and operational observing systems, including 80 Argo floats and 16 surface drifters, 58 high-frequency radars (HFR), 220 tide gauges and 85 tsunami alerting devices, 9 periodic or sustained glider lines, 5 FerryBox lines, 11 wave buoys, 36 subsurface or deep moorings, 46 meteorological and oceanographic surface buoys, 5 seabed platforms or cabled observatories, 13 periodic transects or repeated cruises, and 17 oceanographic stations visited on a regular basis (time-series stations).
The present survey revealed a strong asymmetry in the distribution of these platforms, reflecting a clear discrepancy in the capabilities of different Mediterranean countries. It also shows the difficulty for maintaining long-term observations, the fragility of some of these programs, and the need for national programs with structural and sustainable funds that are not only subject to competitive financial support
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-2632', Anonymous Referee #1, 18 Jul 2026
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RC2: 'Comment on egusphere-2026-2632', Anonymous Referee #2, 11 Aug 2026
The manuscript presents MonGOOS, the regional alliance centered on ocean observing systems in the
Mediterranean Sea. The study is grounded in a census of these systems, conducted in consultation with regional
observation actors across the basin. The consultation methodology is clearly framed, which strengthens the
openness and thoroughness of the inventory. While the manuscript section ordering is classical, it is clear and
logical, and effectively supports the paper's central aim. I particularly appreciated the contextualization effort
given to (i) describe observing systems, (ii) MonGOOS's role within the broader system of global and regional
alliances, and (iii) the authors' justification of the chosen terminology. Overall I think the paper fits its central
purpose and will be useful for the community and recommends acceptance with minor revisions based on the
two subsequent points.
My principal criticism concerns the stated goal of “analyzing the current state of the Mediterranean observation
capabilities" to "evaluating strengths and weaknesses to outline a path for future development," (l175-180) which
I find presently under-done, given its prominence as a primary aim of the paper. A complete assessment of
strength and weaknesses of the observing system would compare modes of ocean variability against existing
observational capabilities, in terms of both resolution and spatio-temporal coverage. I do acknowledge that such
an analysis is not feasible for each and every EOV at the scale of the Mediterranean basin (especially at the
paper level). I find that this point could be tuned down or discussed as a perspective. As an alternative approach,
I suggest the authors connect their manuscript more explicitly to the official EOV framework
(https://doi.org/10.3389/fmars.2026.1737002). Stating for instance which EOVs fall within MonGOOS's scope ;
which EOVs should be better observed for societal needs ; and quantifying how often each EOV is addressed by
observing systems. These simple additions would allow to quantitatively pinpoint underrepresented variables or
categories of variables (physical, biogeochemical, and ecology & ecosystem) and would grant a firmer basis to
the discussion section.
Second, I think the manuscript's form requires tightening. Figures could be improved for aesthetic clarity and, in
some cases, modified to better serve their intended purposes. These issues are flagged in the specific comments
below. While the manuscript's ideas flow smoothly, I found the writing quality to be uneven. Many sentences need
rewriting (e.g., in the section on infrastructures) for typos, grammatical errors, repetition, and inconsistencies.
Sections are also not sequential with section 4.6 appearing twice. Finally, there are inconsistencies in the references
that reference-management software (e.g., Zotero) should easily resolve (e.g., "Milglietta" instead of "Miglietta";
"Liubarsteva" vs. "Liuvaresteva"). These issues are itemized in the technical corrections below.
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- 1
The paper 'The Mediterranean observation systems: MonGOOS analysis of present capabilities, weaknesses and perspectives' by Vargas-Yanez et al. presents a complete and detailed inventory of the ocean observation capabilities in the Mediterranean. The analysis was conducted within the framework of MonGOOS, an international organization dedicated to the coordination of Mediterranean ocean observing systems. The paper provides a detailed and accurate snapshot of the Mediterranean observing systems, highlighting the strengths and weaknesses of the current system.
I really appreciated the paper, as such inventories are difficult to realize due to the fragmentation of observation efforts in Europe. The method is robust, well-explained, and helps non-expert users find their way in the intricate and somewhat incomprehensible world of ocean observation. Additionally, they provide a complete explanation of the governance and organizational framework, which, even for an expert, can sometimes be hard to appreciate.
However, I expected the conclusions to go a little further. Some of the suggestions, derived from the weaknesses identified by the analysis, are certainly true, although somewhat rather generic (e.g., “increase observations in the eastern part of the basin, augment funding and personnel involved, etc.”). Such messages are essential, and there is no doubt that they must be addressed. However, from a consortium of more than 30 scientists, I expected a little more.
I sketch below some points that could be addressed by the authors. They are not mandatory for final publication, but I strongly suggest, at least, treating them partially, as the final relevance of the paper will, in my opinion, be strongly augmented.
I also suggest substantially reducing the initial part of the paper, where definitions and descriptions of the platforms are provided. Although I found it very interesting and well done, this section is not essential for the rest of the paper and could be moved to supplementary material, retaining only the main messages (and Figure 1) in the main text.
Here are some suggestions to improve manuscript relevance:
Again, these are only suggestions, as I consider the paper ready for publication with minor revisions:
Line 395: As mentioned earlier, I suggest reducing the chapter “Current observation capabilities” and moving most of the text to the appendix or supplementary material.
Line 275: For the sake of completeness, also cite surface autonomous devices.
Figure 2: I have some issues with the legend: where are the blue dots? The colors of the bars are not clearly explained.
General comment on figures and tables: I am not convinced that systems not yet deployed (even if funded) should be included in the figures and tables. The future is always uncertain, especially for ocean operations, and secured funding does not guarantee that observing systems will ultimately be deployed. Adding planned systems/points to the figures could be misleading for non-expert readers. I strongly suggest removing them.
Table 5, Second row: The entry should be “Ajaccio” (not “AJACCIOI”). Unless the authors opt to use Corsican, in which case the correct form is “Aiacciu”.
Table 6: I strongly suggest indicating in the table the maximum depth of the stations available for each cruise. Sometimes, even if the bottom depth is great, data are only obtained at the surface or at intermediate depths. For non-expert readers seeking information, this detail could be useful in identifying the most suitable systems for their scientific purposes. Another useful indicator could be the number of stations exceeding 1000 meters depth.
Table 7, Third row: “CNRS/IFREMER” is repeated three times.
Line 821: It would be really informative for non-expert readers to explicitly explain the difference between EOOS and EuroGOOS.
Line 880: Maybe I missed something (it is true that the paper is full of acronyms, a glossary would be really useful), but I am surprised that the authors, in their comprehensive overview of the puzzling governance framework, did not cite specific national coordination initiatives such as Fr-OOS (froos.fr) or It-IOOS (it-ioos.eu). It would also be important to somehow mention the GOOS reform project (goosocean.org/news/call-for-proposals-global-ocean-observing-system-reform-consultancy), which will likely impact the governance of all sub-regional and regional systems, such as MonGOOS.