Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model

Topper, R. P. M.; Meijer, P. Th.

doi:https://doi.org/10.5194/cp-11-233-2015

Articles | Volume 11, issue 2

https://doi.org/10.5194/cp-11-233-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/cp-11-233-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 11, issue 2

Research article

|

16 Feb 2015

Research article |

| 16 Feb 2015

Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model

R. P. M. Topper and P. Th. Meijer

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Final revised paper (published on 16 Feb 2015)
Preprint (discussion started on 25 Jul 2014)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC C1372: 'Review of Topper and Meijer', Anonymous Referee #1, 27 Aug 2014
SC C1453: 'Reviewer #2 comments', Michael Rogerson, 06 Sep 2014
- RC C1455: 'Review', Michael Rogerson, 08 Sep 2014
EC C1580: 'Editor Comment', Uwe Mikolajewicz, 26 Sep 2014
AC C2001: 'Author response', Robin Topper, 28 Nov 2014

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Robin Topper on behalf of the Authors (28 Nov 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Dec 2014) by Uwe Mikolajewicz

RR by Anonymous Referee #1 (25 Dec 2014)

RR by Anonymous Referee #3 (07 Jan 2015)

Suggestions for revision or reasons for rejection

In their paper 'Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high resolution ocean model' Topper and Meijer investigate the effect of changes in the depth of the Strait of Gibraltar on the state of the Mediterranean from a set of sensitivity experiments with a regional ocean model. For very shallow straits they find the suppression of the deep Mediterranean outflow due to hydraulic control.
The authors invoke this mechanism to explain the Messinian salinity crisis.

The experiments are interesting, the model is adequate and the analysis and discussion of the results is almost completely convincing. There are, however, a few shortcomings, most of them minor. The explanation for the mixed layer depth changes in SD100 is not convincing and needs to be improved.
Some of the other conclusions based on a comparison between SD500 and SD100 might be affected by a drift in SD100 (see Fig. 8).

After my opinion it is sufficient, if the editors evaluates the changes.

major point.

line 456
Checking the effect of increasing salinities on the density effect of a cooling I found a (very small) increase with increasing salinities (UNESCO equation of state drho/dT around 18 deg for salinities between 35 and 45). This directly contradicts the following sentences
'At higher salinities, the changes in density caused by cooling of surface water is comparably smaller. As a consequence, lateral and vertical density differences at the surface are smaller and mixed layer depth increases significantly throughout the eastern basin.'
Please demonstrate your point by density calculations!
An alternative explanation for the deeper mixed layers could be a slight model drift towards saltier water, which would destabilize the water column (and thus favour enhanced mixed layer depths).

minor points

line 255... /Fig. 4
- the forcing is very smooothe and the restoring very strong. What causes the east west wave like structures in SST off Libya ( approx. 4 deltax)? As the plot shows 10yr mean data, it cannot be a traveling wave.

- Please use the full colour scale in the salinity plots. That may make it easier to see the structures, especially in the horizontal plots.

Fig. 4 caption
Two horizontal and a vertical cross section...
I never heard the expression 'horizontal cross section' before.

line 312-315
SST and SAT are different quantities, which are somehow related but not identical. Therefore it is not clear to me, why this indicates that water characteristics do not respond linearly to surface forcing.

line 343
near western -> in the western

line 423
Fig. 6 -> Fig. 5

line 535
The new section dealing with the effect of the idealized forcing is definitely an improvement in relation to the original paper. What is still missing here is the discussion of the potential effect of too warm Mediterranean deep and intermediate water (due to the unresolved seasonal cycle) on the net heat budget. This effect should lead to to an underestimation of the temperature difference between inflowing Atlantic and outflowing Mediterranean water.

Table 2
Which reference temperature has been used for the heat transport calculations? Has the heat effect of the net freshwater flux of the surface been taken into account? It not, why not?

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ED: Publish subject to minor revisions (review by Editor) (08 Jan 2015) by Uwe Mikolajewicz

AR by Robin Topper on behalf of the Authors (14 Jan 2015) Author's response Manuscript

ED: Publish as is (26 Jan 2015) by Uwe Mikolajewicz