the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Dec 2023
High resolution observations of the ocean upper layer south of Cape São Vicente, western northern margin of the Gulf of Cadiz
Abstract. This article presents an Eulerian physical and biogeochemical data set from the Iberian Margin Cape São Vicente Ocean Observatory (IbMa-CSV), a facility of the European Multidisciplinary Seafloor and water column Observatory – European Research Infrastructure Consortium (EMSO-ERIC) located 10 nautical miles south of Cape São Vicente (Portugal), the southwest tip of the Iberian Peninsula and western limit of the northern margin of the Gulf of Cadiz. The observatory was installed on the shelf break, and the data time series spans four months for most of the variables. The upper 150 m were sampled intensively with a wave powered vertical profiler at an average rate of 4.5 profiles per hour recording at 2 Hz when ascending at approximate velocity of 0.2 m/s and 10 Hz when descending at variable velocity. The vertical resolution was always higher than 0.2 m. Measured channels were conductivity, temperature, pressure, chlorophyll a, dissolved O2 concentration, and turbidity. Derived channels are sea pressure, depth, salinity, speed of sound, specific conductivity, dissolved O2 saturation, density anomaly, spiciness and Brunt-Väisälä frequency. The acquired data set includes the flow velocity and direction along the water column, taken from an upward looking 300 kHz Acoustic Doppler Current Profiler (ADCP) recorded every hour for 3 m depth bins extending the same depth range of the vertical profiler. A standard quality control scheme was applied to the data set. The data set is preserved for multiple use and is accessible in the SEANOE repository, under the address: https://www.seanoe.org/data/00836/94769/ (Rautenbach et al., 2022).
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RC1: 'Comment on essd-2023-436', Anonymous Referee #1, 20 Dec 2023
Review of "High resolution observations of the upper ocean layer .....)
Summary: As a report on the efforts to make observations as well as a preliminary look at the observations, some content was lacking and suggestions are made here for a revision.
- Goals.A section 2 laying out the goals for this observatory would be a great addition. The introduction lays out the motivation and the methods section shows the hardware, but what were the goals or objectives that drove the choice of the observing tools. Then, later in the paper, one could discuss whether or not the goals were met and how the effort might evolve to have greater success at reaching the goals. As a concrete example, is observing the velocity across the full water column a goal? If so, might in the future a current meter be added to the wave driven profiler? Or, observing the velocity over the full depth is not a goal, so the failure of the ADCP to capture velocity near the surface is not a failing? What is the intended longevity of the observatory? forever? Is this paper discussing just one deployment of an intended long term deployment?
- Methods - clear statement of goals would help the reader understand why the instruments were fitted with the sensors listed.
- Methods - not found but expected here is a discussion of how the mooring designs were chosen.Just to survive expected flows but OK to lean over and get pushed down by drag? Or, designed to be as close as vertical at all times by adjusting float buoyancy? How much do the subsurface moorings get depressed by current?
- Side comment - lettering/labels in Figures could not be read.
- Methods - how often are the moorings recovered and reset? Are the new moorings installed to overlap the old moorings to allow for no gaps in the record? What conditions are the moorings/instruments in when recovered - biofouled, tangled with fishing line?
- Is part of the quality control a comparison of successive deployments - in other words, making the sequential, successive records of similar quality and able to be merged? Are shipboard observations made (like water sampling for in the lab analyses) made to check the instruments? Are recovered instruments post-calibrated before being cleaned and refurbished? Maybe the paper is presenting just one deployment - it is not clear. The abstract says this is an observatory so the reader assumed this is an ongoing long-term deployment with multiple cruises/mooring deployments.
- Processing notes - is there a netcdf header for the files with processing information?For example, was a magnetic deviation correction applied to the velocity data and what was it? Besides serial numbers, do you track and record software and firmware numbers and revisions for each instrument? There looked to be no tracking of calibration information (history, date, coefficients....); where is that available?
- Figs 3 and 4 - hard to read, small labels.
- Fig 6 - got very little out of this figure, small labels, faint contour lines, not the best color palette choices.
- Section 5 Data Records - this is a place where knowing the goals of the observing effort would set the context.For example, is Fig 3 showing success or failure? If the goal was full water column, result is a failure. Be great to have mixed layer depth drawn on top of the velocity contours. Figure 4 - does this address a goal, show success?
- Table 3.Started to read this and realized there is not much information about the time bases of the files? There is some instrument sampling info on page 6. Were instrument clock time bases checked? Were the raw sampling rates maintained in future files or were files taken to some common time base, like 1 hour? What files and time base were used to prepare Table 3? By showing four months, you open the question of whether or not there were statistically significant differences in these numbers month to month, but probably cannot address that due to small number statistics.
- Fig 8 is potentially very nice, but hard to read now with small font, poor color palette for BC frequency (N squared rather than N2).B great to see middle and lower panels with mixed layer depth overplotted. How was spiciness computed?
- The first part of the text in section 7 should have been in the introduction of a section 2, to explain the context and that a one deployment snapshot was being deployed.This section would also make more sense if the goals for observing had been defined early in the paper. also reading the claim about observing mesoscale and submesoscale events makes the reader think there was some point in the velocity roses being shown that was not clear. But with basically a point observatory, how are you able to claim you sampled features defined by their spatial scales (submesoscale and mesoscale)? Are you thinking of this in-situ data set in the context of satellite altimetry or some spatial sampling that would complement these point time series?
Conclusion: Statements like "crucial to understand the complexity of ocean dynamics..." are hard to accept as no ocean dynamics framework that motivated observing goals or no set of science driven questions that gave rise to specific observing requirements were presented. This would be a much better paper if that thought processes that showed the flow from science questions (for example, do eddies transport boluses of different water types or do eddies have associated enhanced vertical mixing) to observing requirements/goals was laid out up front. Then the paper could highlight the successes/failures of the observatory and move on to how the team will iterate to improve the observing effort. As a data presentation alone, it also needs some work and some better figures.
Citation: https://doi.org/10.5194/essd-2023-436-RC1 -
RC2: 'Comment on essd-2023-436', Anonymous Referee #2, 08 Apr 2024
The report is an original and relevant attempt to establish high-resolution observations in the western northern margin of the Cape San Vicent. It reads well. Nevertheless the ms. could have a much broader scope/impact if it integrated more EMSO-ERIC observations. Consequently, the data is considered a limited subset (4 months). Is it possible to include other Regional partners and/or datasets?
Nevertheless, it represents a unique dataset with important uses for the scientific community. What about other users? Are these observations useful to major EU initiatives such as CMEMS? How? Can it complement satellite observations?
The introduction reads like an introduction to the oceanography of the region, however, perhaps a more appropriate approach is to report on other historical observational efforts in the region, their limitations, and thus the importance of this new time series. Perhaps the Portuguese Hydrographic Institute; The European Marine Observation and Data Network (EMODnet); or the Environmental Observatory of the Strait of Gibraltar from CEIMAR could provide good complementary/permanent observations for an historical context. It is important to demonstrate the uniqueness of this dataset. Perhaps by drawing a timeline of all recorded observations in the region? More focus on the type, frequency, and limitations of historical observations and less on the oceanography. Since the authors are not drawing any oceanographic conclusions from the dataset, the introduction does not match the main conclusions.
Data thresholds, data processing, and quality control were well addressed.
Figure legends are small and hard to read.
Citation: https://doi.org/10.5194/essd-2023-436-RC2
Data sets
EMSO-Iberian Margin Cape St. Vincent observatory data (subsurface mooring) from Jun-Oct 2022. Sarah Rautenbach, Paulo Relvas, and Carlos Sousa https://doi.org/10.17882/94769
EMSO-Iberian Margin Cape St. Vincent observatory data (EMSO Generic Instrument Module (EGIM)) from Jun-Oct 2022. Mafalda Carapuço, Miguel Miranda, Carlos Sousa, Sarah Rautenbach, Tanya Silveira, Eduardo Silva, and Hugo Ferreira https://doi.org/10.17882/95468
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