[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

OCMIP Guidelines Phase B2 (Tentative)



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