/[MITgcm]/MITgcm/doc/diags_changes.txt
ViewVC logotype

Diff of /MITgcm/doc/diags_changes.txt

Parent Directory Parent Directory | Revision Log Revision Log | View Revision Graph Revision Graph | View Patch Patch

revision 1.1 by dimitri, Sun Jun 21 23:08:48 2009 UTC revision 1.5 by heimbach, Sat Aug 13 13:34:22 2011 UTC
# Line 1  Line 1 
1    ================================================================
2    Apr 03, 2010
3    1) add diagnostics for KPP non-local flux of Temp, Salt and pTracers
4     (respectively: KPPg_TH, KPPg_SLT and KPPgTrXX for tracer number XX)
5    This allows to close the tracer budget when using KPP.
6    
7    2) Change the diagnostic for KPP non-local term:
8     name:          description:
9    KPPghat         Nonlocal transport coefficient (s/m^2)
10                    (correspond to KPP ghat field, from which the non-local
11                    flux of tracer (T,S,pTr) is computed, as the product of
12                    ghat , KPPdiffKz and surface flux.)
13    replaced by:
14    KPPghatK        ratio of KPP non-local (salt) flux relative to surface-flux
15                    (correspond to the product: KPP_ghat * KPPdiffKzS
16                     which gives the fraction of the the surface flux of Salt
17                     that KPP return as non local flux; also valid for any passive
18                     tracer, but could be different for Temp., see comment below)
19    
20    comments (from mitgcm-devel list):
21     I was also tempted to replace the KPPghat diagnostics
22     with something more useful which incorporates the KPPdiffKz:
23     Since it is the product KPPghat*KPPdiffKz which matters,
24     and given that short time variations of both (which have no
25     reason not to be correlated) can be significant,
26     the product of the 2 time-ave is very likely to be quiet
27     far from the time-ave of the product.
28     It has also the advantage of a simpler interpretation:
29     the product is just the fraction of the surface flux which is
30     treated as non local (no unit, instead of this funny s/m^2
31     for KPPghat).
32    
33     Then I would propose to just pick one KPPdiffKz (for instance,
34     KPPdiffKzS for salinity, since it's also used for Ptracers),
35     and have only 1 diag: "KPPghatK" for KPPghat*KPPdiffKzS (no unit).
36    
37     For temperature (KPPghat*KPPdiffKzT), it's probably not too different
38     from the one computed for salinity (might be in fact a better
39     time-ave value that what we have now, for the reason above).
40     And to get a precise diagnostic of KPP-non-local effect
41     on temperature, there would be this new diagnostic directly from
42     kpp_transport_t.F (which can be used to close a Temp. budget).
43    
44    ================================================================
45  Jun 21, 2009  Jun 21, 2009
46  Some redundancies and relations for model diagnostics:  Some redundancies and relations for model diagnostics:
47    
48  1) Qnet = QNETtave = - oceQnet = SIqnet  1) Qnet = QNETtave = - oceQnet = SIqnet
    for open-ocean: Qnet = EXFqnet = SIqneto  
49    
50  2) EXFqnet = EXFlwnet + EXFswnet - EXFhl - EXFhs  2) For open-ocean, i.e., when there is no sea ice:
51       Qnet = QNETtave = - oceQnet = SIqnet = EXFqnet = SIqneto = SIatmQnt
52    
53    3) EXFqnet = EXFlwnet + EXFswnet - EXFhl - EXFhs
54    
55  3) Qsw = QSWtave = - oceQsw = SIqsw  4) Qsw = QSWtave = - oceQsw = SIqsw
    for open-ocean: Qsw = EXFswnet  
56    
57  4) EmPmR = EmPmRtave = -oceFWflx = SIempmr  5) For open-ocean, i.e., when there is no sea ice:
58       Qsw = QSWtave = - oceQsw = SIqsw = EXFswnet
59    
60    6) EmPmR = EmPmRtave = -oceFWflx = SIempmr
61    
62  ================================================================  ================================================================
63    
# Line 105  And with the default value: salt_EvPrRn= Line 153  And with the default value: salt_EvPrRn=
153   surForcS = oceSflux + SRELAX - [PmEpR*SSS]   surForcS = oceSflux + SRELAX - [PmEpR*SSS]
154    
155  Notes:  Notes:
156  1) here PmEpR is assumed to be the fresh-water mass flux  1) Here PmEpR is assumed to be the fresh-water mass flux
157   per surface area [units: kg/m^2/s] whereas the model variable     per surface area [units: kg/m^2/s] whereas the model variable
158   EmPmR is still a volume flux per surface area [units: m/s].     EmPmR is still a volume flux per surface area [units: m/s].
159  2) with Linear Free surface (nonlinFreeSurf=0), the term  2) With Linear FreeSurf, there is a small loss of heat/salt/tracer at the
160  corresponding to w_surface*SST,SSS is missing in TFLUX,SFLUX     surface (d/dt(Eta) inconsistent with fixed surf grid cell thickness:
161  [might be added later ?] to match exactly the Heat and Salt     a) if linFSConserveTr is set to true (file "data"), then the model
162  budget evolution.        corrects for this (see S/R calc_wsurf_tr.F).
163  --------------------------------------------------------------------------     b) if linFSConserveTr=False (=the default), the term corresponding
164          to w_surface*SST,SSS is missing in TFLUX,SFLUX to match exactly the
165          Heat and Salt budget evolution so need to account for this term in
166          the budget, which can be obtained from the 1rst level
167          of WTHMASS / WSLTMASS diagnostics (diagnostics ADVr_TH / ADVr_SLT
168          is not the right one for this purpose, it's just zero at k=1).
169    3) There is just one more undocumented/hidden case
170       (nonlinFreeSurf=0 & select_rStar=-1) which is not covered.
171    4) For extended diagnostics in the presence of sea-ice and using
172       pkg/seaice/ (in particular atmosphere-ice and ice-ocean fluxes)
173       see online documentation, section 6.6.2.6 "SEAICE diagnostics"
174    
Legend:
Removed from v.1.1  
changed lines
  Added in v.1.5
  ViewVC Help
Powered by ViewVC 1.1.22