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Re: OCMIP Guidelines Phase B2 (Tentative)



Hi Jim,

        I am glad to see you getting things on track for OCMIP.  We had
kind of let the ball drop since our last meeting in Holland (which is why I
think we should meet regularly in the future).

        Re. the following: I went back and consulted my minutes from our
meeting in Holland.  Here is what I have:

Phase B is to coplete bomb and natural 14C, anthropogenic CO2, and the
solubility and biological pumps.

Phase C is to add O2 and 13C

Phase D is to add tracers of ocean circulation, including CFC's, age
tracers with an Austral Ocean source, and multiple decay rate tracers which
would enable separation of mixing and advection.

        What concerns me about the way you have set the guidelines is that
some of the phase B goals under item 3. are going to take a while to get
off the ground, while some of the other tracers could be done sooner.  I
suggest that we try and plan things in order of achievability, so we can
have the satisfaction of seeing ourselve progress through the goals at a
reasonable pace.

        On the other hand, given the remarkable disagreement in models in
the anthropogenic CO2 versus bomb C14 inventory plots, it seems to me that
one of the models we might want to move up to an earlier time slot is the
multiple decay rate tracers so we can get a better grasp on the relative
roles of mixing and advection in the models.

Best regards, JORGE


>Dear "ocmip-all" members,
>
>This is the first message to the mailing list "ocmip-all".  Please see
>the README, sent previously, for information on how to use, subscribe,
>and unsubscribe to this list.  If mail traffic becomes too intense or
>too specialized, I may consider open up sub-lists.
>
>As a first message, I would like to now encourage full discussion
>concerning the formulation of guidelines for OCMIP simulations for
>phase B2 and beyond.
>
>OCMIP is currently in phase B1, as described in the Report from OCMIP
>Workshop I (May 1996).  Phase B2 will not begin until the first papers
>from B1 are submitted, probably sometime around January 1997.  However,
>that is very soon, thus I need your input now to firm up those
>guidelines.  Thus speak now or forever with the OCMIP standards!  Please
>send all responses by October 15, 1996.
>
>Note that these guidelines were first given in rudimentary form in the
>OCMIP Report mentioned above, although only  in rudimentary form.
>Since that report, I have had few responses.  On the other hand, Uwe
>Mikolajewicz for MPI has already made the runs specified in 3.1(a) and
>3.3.  Unless there are strong objections, I would like to take
>advantage of his experience and make the identical runs for OCMIP.
>
>---------------------------------------------------------------------------
>--------------
>Tentative Guidelines for OCMIP Phase B2 and Beyond
>     (Send suggestions by 15 October 1996)
>---------------------------------------------------------------------------
>--------------
>(1) O2 (Phase B2):
>-------
>* Two simulations (Natural + anthropogenic Perturbation)?
>* Gas exchange consistent with CO2 runs (Phase B1)
>* Account for N2 (as a ocean tracer)?
>
>(2) C-13 (Phase B2):
>---------
>
>* Two simulations (Natural + Suess Effect)
>* Gas exchange consistent with previous runs for CO2 (phase B1)
>* Consider biological production constant at a value of -22 per mil,
>relative to TCO2
>* fractionation factors?
>
>
>3. Numerical Tracers (Phase B2):
>---------------------
>3.1 Age Tracer reset to zero at the surface
>    (a) In all and/or part of the Southern Ocean
>    (b) Over whole ocean (suggested by Uwe Mikolajewicz)
>
>    * Reset to zero at the surface, wherever sea-ice is < 99%
>      (in the area of interest)
>    * Aging every time step by ratio dt/1y
>    * Result: age in yr
>
>3.2 "Dye" Tracer (conservative, pulse input) also for S. Ocean?
>
>3.3 Other tracers to study century-scale (and shorter) processes
>
>    At the workshop two of the following were mentioned while the third was
>    suggested recently by Uwe:
>
>    (a) A short-lived (fictitious) tracer (mean life 20 yr)
>    (b) Ar-39 (mean life 388 yr)
>    (c) C-14  (mean life 8237 yr)
>
>    * Infinitely rapid gas exchange (To simplify comparison)
>      Thus surface concentrations eternally set to zero everywhere
>      (except where sea ice cover > 99%.
>    * Finite gas exchange for Ar-39 (an additional run) is proposed
>      to better compare model results to data.
>
>    * Advantages/Results: - mean lives  exhibit ratios of 1:20
>                          - can help deduce advection vs. diffusion
>
>4. CFC's (Phase C):
>---------
>* Warner and Weiss Solubility
>* Piston Velocity (same as for CO2, but corrected via Schmidt number
>  dependence and no chemical enhancement (Wanninkhof, 1992). The analysis
>  center will provide this 2-D field (as we have for CO2), along with
>  documentation)
>* Atmospheric Record (most recently available from Weiss, thanks to N. Gruber
>                      for this lead)
>---------------------------------------------------------------------------
>--------------
>
>Best regards, Jim

Jorge L. Sarmiento
AOS Program, Princeton U.
Sayre Hall, Forrestal Campus
P.O. Box CN710
Princeton, NJ 08544-0710

Tel. (609) 258-6585
Fax. (609) 258-2850
E-mail: jls@splash.princeton.edu