the Creative Commons Attribution 4.0 License.
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| 14 Aug 2024
A New Vision of the Adriatic Dense Water Future under Extreme Warming
Abstract. We use the Adriatic Sea and Coast (AdriSC) kilometer-scale atmosphere-ocean model to assess the impact of a far-future extreme warming scenario on the formation, spreading, and accumulation of both the North Adriatic dense Water (NAddW) over the entire basin, including the Jabuka Pit accumulation site, and the Adriatic Deep-Water (AdDW) over the Southern Adriatic Pit (SAP). Our key findings differ from previous studies that used coarser Mediterranean climate models and did not update the thresholds for dense and deep- water definitions to account for the far-future background density changes caused by warmer sea surface temperatures. We show that surface buoyancy losses at NAddW generation sites, driven by evaporation, are expected to increase by 15 % under extreme warming, despite a 25 % reduction in the intensity and spatial extent of Bora winds. As a result, future NAddW formation will remain similar to present conditions. However, the volume of dense water in the Jabuka Pit will decrease due to the increased far-future stratification. Additionally, dense water transport between the Jabuka Pit and the deepest part of the SAP will stop, as future NAddW will be lighter than the AdDW. Regarding Ionian-Adriatic exchanges, extreme warming will not affect the impact of the Bimodal Oscillation System on the Adriatic salinity variability, but future AdDW dynamics will be determined by density changes in the northern Ionian Sea. Our findings highlight the complexity of climate change impacts on Adriatic atmosphere-ocean processes and the importance of high-resolution models for more accurate far-future projections in the Adriatic Sea.
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RC1: 'Comment on egusphere-2024-2524', Anonymous Referee #1, 27 Aug 2024
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Review of «A New Vision of the Adriatic Dense Water Future under Extreme Warming» by Denamiel et al.
The authors investigated the future evolution of dense and deep water formation in the Adriatic Sea, as well as its further spread and accumulation at different locations in the sub-basin, following the pseudo global warming (PGW) approach under the RCP8.5 emissions scenario. For this purpose, the authors use kilometer-scale simulations performed with the Adriatic Sea and Coast (AdriSC) climate model. The AdriSC model has already been evaluated in previous work. By the end of the century, the authors find a NaddW formation similar to the present climate, while the AdDW formation is expected to decrease. The authors report some new findings that make the article very interesting. Indeed, the evolution and mechanism of deep water formation is a central topic in oceanography, especially in the Mediterranean Sea. Its future changes could have implications for regional circulation, biogeochemistry and marine ecosystems. In my opinion, the main novelty of this work is that the authors have examined the future effects on the dynamics of the NaddW and the AdDW separately, thanks to the use of kilometer-scale simulations.
The manuscript is generally well written and organized, and the results are relevant to the scientific community, especially the Mediterranean community. However, I found some points that should be improved before its publication in OS.
1) Throughout the manuscript, the authors compare their results with those previously obtained by Parras-Berrocal et al. (2023) using a future projection performed with one of the coupled regional models participating in the Med-CORDEX initiative. However, I also miss a discussion with the results obtained by Soto-Navarro et al. (2020), who analyzed the future evolution of deep water formation in the Adriatic Sea with an ensemble of fully coupled regional climate models from the Med-CORDEX. In this study, some models predict a decrease in deep water formation in the Adriatic, while others predict an increase. My advice is to try to position AdriSC within the Med-CORDEX ensemble. Does AdriSC project an average or an extreme behaviour with respect to the rest of the model simulations? The results in Soto-Navarro et al. 2020 (Table 8 and Figure S19) should help you to reinforce this point in the introduction and in the discussion.
2) Regarding Figure 1, what criteria do you use to define the 5 subdomains (coloured polygons)? It should be stated somewhere in the text. Perhaps you could change the colour of the DKB polygon as it is quite similar to the colour used in NA. Could you include the meaning of MSL in the caption? The acronym MSL is not defined anywhere in the text.
3) One of my main concerns is that throughout the manuscript the authors give values for the differences between the RCP85 and historical periods. However, in most cases these differences are not easy to visualise in the figures because the authors show the historical and RCP8.5 periods separately. I strongly recommend that Figures 6, 7, 10, 11, 12 be redesigned to include a third column with the differences, or that both periods be combined in one column and the differences added in a second column. This would make the manuscript easier to follow.
4) Lines 333-336: What about the possibility of including a new subdomain located offshore NA and KB sites in the analysis?
5) In Figure 13, the SI appears to be calculated for the DJFM period. This is strange if the aim is to estimate the resistance of the water column to convection. Please consider computing it for a period before convection (for example in December or in autumn).
6) Please add letters to the figure panels at least in Figures 14 and 15. This will make the text easier to read and understand. Captions should be rewritten accordingly.
7) Figure 16 is not easy to understand on its own. I would recommend following the numerical order used in the conclusions section to reorganize the figure, giving the same number to the processes involved in each conclusion. Otherwise, I would recommend removing Figure 16.
Minor remarks:
- L44: include density value of densest water based on previous literature.
- L60: Regional Climate Model (RCM) → Regional Climate System Model (RCSM)
- Section 2.1.2: Could you indicate the length of the spin-up?
- In Figure 2, as well as in 3, 13, 14, I would recommend using Depth instead of Height.
- L117: Please include a reference to the definition of extreme Bora events (i.e. gale-force winds).
- L144: I would suggest replacing the term Dense Water Height (DWH) with isopycnal depth.
- In Figure 3, could you use the same colorbar range in both top panels? Another option is to include a sentence in the caption stating that different colorbar ranges are used to better visualize the figures.
- Line 153: “… summarized with box plots (Figure 13)..”
- Figure 4: I would suggest including the vector field.
- Lines 212-217: This paragraph is hard to follow. In the text, the horizontal wind transport ranges from 20 to 2800 × 10⁹ m³/s, while in Figure 6 it ranges from 0 to 8 [10⁹ m³/s]. Please clarify the order of magnitude used.
- Line 312: In terms of the Naddw transports (Figure 12). Sometimes in the text the authors do not refer to the figure they are talking about. Please check the whole manuscript.
- Line 327: In Parras-Berrocal et al. (2013), the authors consider NaddW and AdDW as Adriatic Deep Water without distinction due to the coarse resolution of the RCSM used.
- L345-346: “ (i.e., shift in peak reduction in dense water transports between T3 and T4; Fig. 12)” I do not fully understand what the authors
- Line 351: 29.09 kg/m³ → 28.4 kg/m³?
- Line 371: Modified Atlantic Water → Atlantic Water
References of this review not already cited by the authors:
Soto-Navarro, J., Jordá, G., Amores, A., Cabos, W., Somot, S., Se- vault, F., Macias, D., Djurdjevic, V., Sannino, G., Li, L., and Sein, D.: Evolution of Mediterranean Sea water properties un- der climate change scenarios in the Med-CORDEX ensemble, Clim. Dynam., 54, 2135–2165, https://doi.org/10.1007/s00382-019-05105-4, 2020.
Citation: https://doi.org/10.5194/egusphere-2024-2524-RC1 -
AC1: 'Reply on RC1', Clea Denamiel, 14 Sep 2024
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Please see anwers in the attached file.
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AC1: 'Reply on RC1', Clea Denamiel, 14 Sep 2024
reply
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RC2: 'Comment on egusphere-2024-2524', Anonymous Referee #2, 08 Sep 2024
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Review of the paper
A New Vision of the Adriatic Dense Water Future under Extreme Warming
Author(s): Clea Lumina Denamiel et al.
MS No.: egusphere-2024-2524
MS type: Research articleA kilometer-scale atmosphere-ocean model is used to assess the impact of a far-future extreme warming scenario on the formation, spreading and accumulation of the dense water in the Adriatic Sea.
The text is well written and results are presented clearly. I recommend minor corrections:
Specific comments:
105 : Please better explain the PGW approach and its consequences on the model behavior, as it is a key point for the paper.
455 : The choice of the boundary conditions and its implication on the exchange at the southern border are not well described. Could authors further discuss this point.
Citation: https://doi.org/10.5194/egusphere-2024-2524-RC2 -
AC2: 'Reply on RC2', Clea Denamiel, 14 Sep 2024
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Response to Reviewer #2
A kilometer-scale atmosphere-ocean model is used to assess the impact of a far-future extreme warming scenario on the formation, spreading and accumulation of the dense water in the Adriatic Sea.
The text is well written and results are presented clearly. I recommend minor corrections:
Answer: Thanks a lot for your interest in our study and for pointing out below ways to improve the manuscript.
105 : Please better explain the PGW approach and its consequences on the model behavior, as it is a key point for the paper.
455 : The choice of the boundary conditions and its implication on the exchange at the southern border are not well described. Could authors further discuss this point.
Answer: The authors agree that the PGW method can be better described and that the consequences of having boundary conditions within the northern Ionian Sea must also be explained. The following paragraph will be added in section 2.1.2: “For the atmosphere, the ERA-Interim air temperature, relative humidity, and horizontal wind velocities, defined on 37 atmospheric pressure levels, are modified between 1000 and 70 hPa with the climatological changes ΔT, ΔRH, ΔU, and ΔV, respectively. These changes are derived from the RCP 8.5 scenario of the LMDZ4-NEMOMED8 RCSM by subtracting the atmospheric results of the 1987–2017 period from those of the 2070–2100 period, producing 6-hourly three-dimensional climatological changes for the 366 days of the year. These new forcings are then used to provide the boundary and initial conditions for the WRF 15-km model in the PGW simulation. For the ocean, the MEDSEA ocean temperature, salinity, and currents, defined on 72 unevenly spaced vertical levels, are modified with the climatological changes ΔT ocean, ΔS ocean, ΔU ocean, and ΔV ocean, respectively. These changes are also derived from the RCP 8.5 scenario of the LMDZ4-NEMOMED8 RCSM to produce three-dimensional daily climatological changes for the 366 days of the year. These forcings are then used to provide the boundary and initial conditions for the ROMS 3-km model in the PGW simulation. In other words, the same climatological changes are used to modify the boundary conditions for each simulated year of the reanalysis period and the PGW simulations "inherit" the synoptic environment and weather/ocean conditions from the atmosphere-ocean reanalyses at the lateral boundaries. As a result, the main limitation of this methodology, compared to traditional downscaling techniques (Brogli et al., 2023), is that potential changes in intra-annual and interannual variability may be missed in the PGW projections. Additionally, in the presented RCP 8.5 simulation, due to the location of the AdriSC ROMS 3-km boundary conditions, the northern Ionian ocean dynamics may be more influenced by the MEDSEA reanalysis than by the projected climatic changes.”
Citation: https://doi.org/10.5194/egusphere-2024-2524-AC2
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AC2: 'Reply on RC2', Clea Denamiel, 14 Sep 2024
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Data sets
A New Vision of the Adriatic Dense Water Future under Extreme Warming Clea Denamiel https://osf.io/cxtfb/
Model code and software
AdriSC Climate Model: Evaluation Run Clea Denamiel https://osf.io/zb3cm
Video supplement
Animation of the Adriatic dense and deep- water under far-future extreme warming Clea Denamiel https://osf.io/8em3f/
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