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Re: OM paper (fwd)

Dear Jean-Claude and Jim,

Sorry this is late but warmest congratulations to all the team.



>Good news
>I've just received the comments from the reviewver of the CFC paper.
>The comments are good, and the paper is recommanded for publication after
>minor revision.
>I will do these minor changes rapidly and resubmit it soon for
>publication. I won't be able to do it before too weeks, I am now in
>vacation for renovating my house.
>If you have some comments on the review (see below) or any suggestion,
>please send it to me before I answer to the editor.
>Jean-Claude DUTAY
>Laboratoire de Modelisation du Climat et de l'Environnement
>DSM, Orme des Merisiers, Bat 709
>CE Saclay
>91191 Gif sur Yvette Cedex
>Tel : 33-1-69 08 31 12
>Fax : 33-1-69 08 77 16
>email : dutay@lmce.saclay.cea.fr
>---------- Forwarded message ----------
>Date: Thu, 9 Nov 2000 10:44:57 +0000 (GMT)
>From: Ocean Modelling Editors <omod@soc.soton.ac.uk>
>To: dutay@lsce.saclay.cea.fr
>Subject: OM paper
>Dear Dr. Dutay et al,
>Below are the referee comments on your OM paper "Evaluation of ocean 
>model ..."
>from which you will see that both referees liked your paper a lot. Not
>surprisingly, they did have some suggestions, mostly fairly minor, which will
>need addressing.
>When you resubmit, please include a letter detailing how you handled these
>concerns. I may or may not send the paper out again depending on my reading of
>the letter and the paper.
>I hope to hear from you shortly!
>Peter Killworth
>P.S. Referee 1 explains why the refereeing time was longer than I like. Non
>mea culpa!
>Referee 1:
>Review of "Evaluation of ocean model ventilation with CFC-11:
>comparison of 13 global ocean models" by J.-C. Dutay et al.
>First an apology from this reviewer regarding the delay in this
>response.  Since I received this paper to review several weeks ago, I
>have made four trips covering 16 time zones.  The Editor tried his
>best, but I was unable to write this review earlier.
>I have a number of comments about this manuscript which range in
>importance from minor to moderately major:
>1)  The manuscript is not carefully prepared.  I realize that the first
>author is not a native English speaker, but many of the errors should
>be found by an English spelling checker.  Failing that, many of the
>co-authors are native English speakers, and any of them who actually
>read the paper could have easily made it more readable.  The errors
>include unmatched parentheses, one of the authors' names spelled with
>an "0" instead of an "O", authors' names in the references or citations
>misspelled,  US states misspelled, "CO2" without the subscript or with
>an "0" instead of an "O", mixed British and US spelling such as
>"modelled" versus "modeled", etc.  Water mass names such as Circumpolar
>Deep Water should be capitalized.  Also, manuscripts without page
>numbers should not be accepted for review because they make it very
>difficult to identify the passages cited in the reviewer's comments.
>In this case, I have numbered my copy by hand and I will use these
>numbers in this review.
>2)  Page 2, last line, and page 9, first line:  It is likely that the
>Southern Ocean (note capitalization) is the region of largest
>anthropogenic CO2 uptake, but I don't believe that there is any
>observational evidence to support this supposition.  Indeed, the
>oceanic radiocarbon evidence suggests that carbon exchange in this
>region is limited, perhaps by ice cover in winter and by a fresh water
>cap in summer.  One might look at the recent work of Sabine, Gruber and
>others for some direct evidence of this uptake rate, but it would be
>wiser not to make such a definite statement.  Surely to use model
>calculations to come to this conclusion would be unwise in the light of
>the main thrust of this paper.
>3)  It would be helpful to cite original data references for the CFC
>data used in these model comparisons.  In many cases there are
>published data reports which should be cited (and their "metadata" read
>by the data users).
>4)  Page 7, Equations 1 and 2:  There is a problem with the treatment
>of water vapor in Equation 1.  If "alpha" is indeed the solubility
>coefficient, then the vapor pressure of water at the interface (Pw,
>normally taken as the vapor pressure of seawater at the potential
>temperature and salinity of the water parcel) needs to be included in
>the equation by replacing "P/P0" with "(P-Pw)/P0".  Alternatively if
>"alpha" is really the solubility function "F" (see Warner and Weiss,
>1985) that includes the water vapor term, then the formulation is
>correct but "alpha" should be "F".  Also, the manuscript is
>inconsistent in using both "k" and "kw" for the transfer velocity or
>exchange coefficient.
>5)  Page 7, paragraph 1:  The Walker et al. atmospheric source function
>is published (JGR,105, 14,285, 2000).  Also, the values are based on
>simple modeling of industrial production and release data plus
>measurements in the recent part of the record.  The records are not
>6)  Figure 1:  Change "f11" to "CFC-11" and "f12" to "CFC-12" in the
>legend of the top panel.  Why include CFC-12 in the top panel anyway,
>since CFC-12 is not discussed in this paper?  Also, change "pptv" to
>"ppt" because the values are given in mole fractions and these are not
>equivalent to volume ratios if the gases in question are not ideal
>(CFC-11 is very non-ideal -- it is a liquid at standard conditions).
>Finally, if CFC-12 is not shown, the title at the top of the top panel
>should be "CFC-11 Atmospheric Mole Fractions".  These are not partial
>pressures!  Change the figure caption accordingly, as well.
>7)  Page 10, line 3, and Figures 4, 6, 11 and 11bis:  I am bothered by
>the units of the "Pcfc inventory" in the middle panels of these plots.
>If I integrate pressure I get units of pressure times length.  Thus it
>could be "atm m" (x 10^-12), but definitely not "ppt mm" (or "pptv. mm"
>as written).  This should be sorted out.
>8)  Page 13, last paragraph, line 3:  The Ajax prime meridian section
>was measured in 1983-84.
>9)  Page 19:  The discussion of Southern Ocean ventilation processes is
>written without recognition of the importance of shelf-edge processes
>in the formation of deep and bottom waters in this region (e.g. Carmack
>and Foster, 1975; Foster and Carmack, 1976).  It is my understanding
>that since the models generally lack the resolution to resolve these
>processes, they must resort to open-ocean convective processes to
>simulate ventilation and mixing that is actually driven by very cold
>and saline waters flowing off the continental shelves and descending
>into the abyss.  This is bound to give a distorted picture of deep
>water ventilation.
>    This is an interesting and important contribution.  The
>distributions of CFCs in the real ocean obviously provide the means of
>critically diagnosing the ability of GCMs to simulate (or in the case
>of the adjoint approach, reproduce) mean ventilation processes in the
>real ocean.  People who are not modelers (and some who are) need a way
>to calibrate themselves concerning the ability of these models to
>simulate and ultimately predict the behavior of oceanic processes
>relevant to climate and climate change.  CFCs may well provide the best
>present diagnostic.  This paper is written honestly and
>straightforwardly.  Most of the points raised in my comments above will
>be easy to address.  The last comment above (Comment 9) is probably the
>most important substantive concern, but this too should be easy to
>address.  Because of its very nature, most of this paper is
>descriptive, and one cannot expect it to propose a cure for the
>problem.  It is sufficient to lay out the facts, and this paper
>generally does this very well.  I recommend publication after
>appropriate revision.
>Referee 2:
>I include below my review of the paper by Dutay et al. submitted to
>Ocean Modeling.  Overall, I liked the paper and recommend that
>it be accepted for publication subject to a satisfactory response
>to my comments and questions below.
>Several of the figures kept crashing my printer.  I don't know if this
>is a problem with my printer (although I've never had it occur before)
>or the postscript files, but I thought I would let you know.
>Review of "Evaluation of ocean model ventilation with CFC-11:
>comparison of 13 global ocean models", by Dutay et al.
>This paper sets the ambitious goal of comparing CFC distributions
>in 13 global models to observations and each other, and also
>attempting to interpret differences between models and data
>in terms of the model formulations.  While there are naturally
>some limitations with direct relationships to model design,
>I think that overall the paper achieves its goal.  I have some
>suggestions and questions for the author's consideration, but I
>found no major flaws with the paper.  I recommend that it be accepted
>for publication in Ocean Modeling, provided the following issues
>are addressed.
>The subject and verb are often not in agreement (e.g. in the
>Abstract, "This analysis charactarize (sp)..." or "Large range
>in the ... are largely...").  Such errors need to be corrected
>throughout.  A spell check would also be a good idea.
>Some mention of the model performance in the Atlantic should be
>included in the Abstract, both NADW and STMW.
>The integrated inventory and penetration depth figures are very
>difficult to read.  It would be a help if the lines corresponding
>to different models were done in different colors.
>Page 3:  I do not get the connection between including river
>input and the evaluation of the thermohaline circulation.
>Page 4:  It should be noted that, although the concentrations of
>CFCs can be measured to high precision, the spatial and temporal
>resolution of the data is very low.
>Page 10:  Label Figure 4 as a, b, c.  Fig4b in the sentence
>"In the observations, the geatest (sp) CFC-11..." should be
>Fig. 4c.  To what extent is the shallow penetration depth
>in the subpolar gyre due to treatment of the marginal sea and
>strait exchange?
>It is interesting that there is not always a correspondence
>between depth of penetration and inventory, is this a
>reflection of errors in the stratification?
>What are the uncertainties in the data due to spatial coverage,
>temporal and spatial variability in the ocean, and interpolation?
>Can you provide error bars?
>Page 11:  Three of the four models that have very low CFC uptake
>in the subtropical gyre are forced with annual means.  Such
>forcing does not correctly reproduce the deep winter mixed
>layers and subduction that is strongly seasonally aliased.
>Most of the models also seem to exaggerate the deep maximum at
>~1200m (Fig. 5), although this does not show up in the summary
>diagnostics (Fig. 6).  Where is this deep maximum in NADW coming
>from?  Are the models convecting too deep elsewhere and it
>is being advected into the eastern NA?  Is it related to the
>poor treatment of overflows?
>What is the treatment of the Med in each of the models?
>Page 12:  Mark the data in Fig. 7 in degrees W, as the models
>and discussion use.  Does the DWBC velocity core correspond
>to the tracer core?
>Page 13:  Shade the data figure as the model figures.  It would
>be useful to know if the different tracer distributions along
>the western boundary are due to mixing parameterizations or
>advection.  Are the DWBC narrow (usual Munk layer width) or
>wide in those that spread tracers into the interior?
>Figure 12:  Shade the data as the model results.
>Discussion:  Can you be more explicit about the cause of
>the failure of the Subantarctic mode water ventilation
>in models with horizontal mixing?
>Is it due to the direction of mixing (isopycnal, pressure),
>eddy tracer transports, or differences in the mean flow?
>What is the diapycnal mixing parameterization in the NERSC
>isopycnal model?  This is likely too small so that NADW
>goes too deep and there is excessive CFC uptake around
>What is the motivation/justification for the particular
>parameterization of brine rejection used in the LLNL model?
>If it is not model tuning, be more specific.
>The GM type eddy parameterization will probably overestimate
>mixing in the DWBC because it neglects the stabilizing
>influence of bottom topography.
>Conclusion:  The circulation fields are never discussed, and
>certainly not evaluated or compared, in this paper.  The
>first sentence is misleading.
>Ocean Modelling; editor
>Dr. Peter D. Killworth, James Rennell Division for Ocean Circulation
>and Climate, Southampton Oceanography Centre, Empress Dock, Southampton
>SO14 3ZH, England.
>Tel: +44 (0)23-80596202
>Fax: +44 (0)23-80596204
>Email: P.Killworth@soc.soton.ac.uk
>Web: http://www.soc.soton.ac.uk/JRD/PROC/people/pki/pki.html
>Ocean Modelling Newsletter: http://www.elsevier.nl/locate/omodol/

Professor Berrien Moore III
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