MITgcm/doc/diags_changes.txt

================================================================
Apr 03, 2010
1) add diagnostics for KPP non-local flux of Temp, Salt and pTracers
 (respectively: KPPg_TH, KPPg_SLT and KPPgTrXX for tracer number XX)
This allows to close the tracer budget when using KPP.

2) Change the diagnostic for KPP non-local term:
 name:          description:
KPPghat         Nonlocal transport coefficient (s/m^2)
                (correspond to KPP ghat field, from which the non-local
                flux of tracer (T,S,pTr) is computed, as the product of
                ghat , KPPdiffKz and surface flux.)
replaced by:
KPPghatK        ratio of KPP non-local (salt) flux relative to surface-flux
                (correspond to the product: KPP_ghat * KPPdiffKzS
                 which gives the fraction of the the surface flux of Salt
                 that KPP return as non local flux; also valid for any passive
                 tracer, but could be different for Temp., see comment below)

comments (from mitgcm-devel list):
 I was also tempted to replace the KPPghat diagnostics
 with something more useful which incorporates the KPPdiffKz:
 Since it is the product KPPghat*KPPdiffKz which matters,
 and given that short time variations of both (which have no
 reason not to be correlated) can be significant,
 the product of the 2 time-ave is very likely to be quiet
 far from the time-ave of the product.
 It has also the advantage of a simpler interpretation:
 the product is just the fraction of the surface flux which is
 treated as non local (no unit, instead of this funny s/m^2
 for KPPghat).

 Then I would propose to just pick one KPPdiffKz (for instance,
 KPPdiffKzS for salinity, since it's also used for Ptracers),
 and have only 1 diag: "KPPghatK" for KPPghat*KPPdiffKzS (no unit).

 For temperature (KPPghat*KPPdiffKzT), it's probably not too different
 from the one computed for salinity (might be in fact a better
 time-ave value that what we have now, for the reason above).
 And to get a precise diagnostic of KPP-non-local effect
 on temperature, there would be this new diagnostic directly from
 kpp_transport_t.F (which can be used to close a Temp. budget).

================================================================
Jun 21, 2009
Some redundancies and relations for model diagnostics:

1) Qnet = QNETtave = - oceQnet = SIqnet

2) For open-ocean, i.e., when there is no sea ice:
   Qnet = QNETtave = - oceQnet = SIqnet = EXFqnet = SIqneto = SIatmQnt

3) EXFqnet = EXFlwnet + EXFswnet - EXFhl - EXFhs

4) Qsw = QSWtave = - oceQsw = SIqsw

5) For open-ocean, i.e., when there is no sea ice:
   Qsw = QSWtave = - oceQsw = SIqsw = EXFswnet

6) EmPmR = EmPmRtave = -oceFWflx = SIempmr

================================================================

Nov 19, 2006 (after tag checkpoint58r_post)

I) Some diagnostics have been renamed (essentially, to better
match the content):

1) name:        description (oceanic set-up):
PRESSURE        Cell-Center Height
replaced by:
RCENTER         Cell-Center Height

2) name:        description (oceanic set-up):
TICE            heat from melt/freeze of sea-ice, >0 increases theta
replaced by:
oceFreez        heating from freezing of sea-water (allowFreezing=T)

3) name:        description (oceanic set-up):
TAUX            zonal surface wind stress, >0 increases uVel
TAUY            meridional surf. wind stress, >0 increases vVel
replaced by:
oceTAUX         zonal surface wind stress, >0 increases uVel
oceTAUY         meridional surf. wind stress, >0 increases vVel

4) name:        description (oceanic set-up):
SWFLUX          net upward SW radiation, >0 increases theta
replaced by:
oceQsw          net Short-Wave radiation (+=down), >0 increases theta

5) name:        description (oceanic set-up):
DIFx_TH         Zonal      Diffusive Flux of Pot.Temperature
DIFy_TH         Meridional Diffusive Flux of Pot.Temperature
replaced by:
DFxE_TH         Zonal      Diffusive Flux of Pot.Temperature
DFyE_TH         Meridional Diffusive Flux of Pot.Temperature

6) name:        description (oceanic set-up):
DIFx_SLT        Zonal      Diffusive Flux of Salinity
DIFy_SLT        Meridional Diffusive Flux of Salinity
replaced by:
DFxE_SLT        Zonal      Diffusive Flux of Salinity
DFyE_SLT        Meridional Diffusive Flux of Salinity

-----------------------------------------------
II) Change description of existing diagnostics:

name:           old description (oceanic set-up):
TFLUX           net surface heat flux, >0 increases theta
SFLUX           net surface salt flux, >0 increases salt
name:           new description (oceanic set-up):
TFLUX           total heat flux (match heat-content variations), >0 increases theta
SFLUX           total salt flux (match salt-content variations), >0 increases salt

-----------------------------------------------
III) New diagnostics have been added:

name:           description (oceanic set-up):
atmPload        Atmospheric pressure loading
sIceLoad        sea-ice loading (in Mass of ice+snow / area unit)
oceQnet         net surface heat flux into the ocean (+=down), >0 increases theta
oceFWflx        net surface Fresh-Water flux into the ocean (+=down), >0 decreases salinity
oceSflux        net surface Salt flux into the ocean (+=down), >0 increases salinity
surForcT        model surface forcing for Temperature, >0 increases theta
surForcS        model surface forcing for Salinity, >0 increases salinity

--------------------------------------------------------------------------
Relation between surForcT,surForcS and others surface forcing diagnostics:
 [x] = average of model variable "x" over the diagnostic time interval

a) if useRealFreshWaterFlux=F or (nonlinFreeSurf=0 & usingZCoords=T)
 surForcT = oceQnet  + TRELAX - oceQsw
 surForcS = oceSflux + SRELAX - [PmEpR*So]
  (with So = local Sea-Surface Salinity (SSS) if convertFW2Salt=-1
    and So = convertFW2Salt otherwise)
 oceFWflx = [PmEpR]
 TFLUX = surForcT + oceQsw + oceFreez
 SFLUX = surForcS

b) if useRealFreshWaterFlux=T & (nonlinFreeSurf>0 or usingPCoords=T),
In general:
 surForcT = oceQnet  + TRELAX - oceQsw + [T_dilution_effect]*Cp
 surForcS = oceSflux + SRELAX          + [S_dilution_effect]
    where T_dilution_effect = PmEpR*( temp_EvPrRn - SST )
      and S_dilution_effect = PmEpR*( salt_EvPrRn - SSS )
 oceFWflx = [PmEpR]
 TFLUX = surForcT + oceQsw + oceFreez + [PmEpR*SST]*Cp
 SFLUX = surForcS + [PmEpR*SSS]

And with the default value: salt_EvPrRn=0. & temp_EvPrRn=UNSET_RL
 (=> no dilution effect on Temp.):
 surForcT = oceQnet  + TRELAX - oceQsw
 surForcS = oceSflux + SRELAX - [PmEpR*SSS]

Notes:
1) Here PmEpR is assumed to be the fresh-water mass flux
   per surface area [units: kg/m^2/s] whereas the model variable
   EmPmR is still a volume flux per surface area [units: m/s].
2) With Linear FreeSurf, there is a small loss of heat/salt/tracer at the
   surface (d/dt(Eta) inconsistent with fixed surf grid cell thickness:
   a) if linFSConserveTr is set to true (file "data"), then the model 
      corrects for this (see S/R calc_wsurf_tr.F).
   b) if linFSConserveTr=False (=the default), the term corresponding
      to w_surface*SST,SSS is missing in TFLUX,SFLUX to match exactly the
      Heat and Salt budget evolution so need to account for this term in
      the budget, which can be obtained from the 1rst level
      of WTHMASS / WSLTMASS diagnostics (diagnostics ADVr_TH / ADVr_SLT
      is not the right one for this purpose, it's just zero at k=1).
3) There is just one more undocumented/hidden case
   (nonlinFreeSurf=0 & select_rStar=-1) which is not covered.
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
46	Some redundancies and relations for model diagnostics:
47
48	1) Qnet = QNETtave = - oceQnet = SIqnet
49
50	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	4) Qsw = QSWtave = - oceQsw = SIqsw
56
57	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
64	Nov 19, 2006 (after tag checkpoint58r_post)
65
66	I) Some diagnostics have been renamed (essentially, to better
67	match the content):
68
69	1) name: description (oceanic set-up):
70	PRESSURE Cell-Center Height
71	replaced by:
72	RCENTER Cell-Center Height
73
74	2) name: description (oceanic set-up):
75	TICE heat from melt/freeze of sea-ice, >0 increases theta
76	replaced by:
77	oceFreez heating from freezing of sea-water (allowFreezing=T)
78
79	3) name: description (oceanic set-up):
80	TAUX zonal surface wind stress, >0 increases uVel
81	TAUY meridional surf. wind stress, >0 increases vVel
82	replaced by:
83	oceTAUX zonal surface wind stress, >0 increases uVel
84	oceTAUY meridional surf. wind stress, >0 increases vVel
85
86	4) name: description (oceanic set-up):
87	SWFLUX net upward SW radiation, >0 increases theta
88	replaced by:
89	oceQsw net Short-Wave radiation (+=down), >0 increases theta
90
91	5) name: description (oceanic set-up):
92	DIFx_TH Zonal Diffusive Flux of Pot.Temperature
93	DIFy_TH Meridional Diffusive Flux of Pot.Temperature
94	replaced by:
95	DFxE_TH Zonal Diffusive Flux of Pot.Temperature
96	DFyE_TH Meridional Diffusive Flux of Pot.Temperature
97
98	6) name: description (oceanic set-up):
99	DIFx_SLT Zonal Diffusive Flux of Salinity
100	DIFy_SLT Meridional Diffusive Flux of Salinity
101	replaced by:
102	DFxE_SLT Zonal Diffusive Flux of Salinity
103	DFyE_SLT Meridional Diffusive Flux of Salinity
104
105	-----------------------------------------------
106	II) Change description of existing diagnostics:
107
108	name: old description (oceanic set-up):
109	TFLUX net surface heat flux, >0 increases theta
110	SFLUX net surface salt flux, >0 increases salt
111	name: new description (oceanic set-up):
112	TFLUX total heat flux (match heat-content variations), >0 increases theta
113	SFLUX total salt flux (match salt-content variations), >0 increases salt
114
115	-----------------------------------------------
116	III) New diagnostics have been added:
117
118	name: description (oceanic set-up):
119	atmPload Atmospheric pressure loading
120	sIceLoad sea-ice loading (in Mass of ice+snow / area unit)
121	oceQnet net surface heat flux into the ocean (+=down), >0 increases theta
122	oceFWflx net surface Fresh-Water flux into the ocean (+=down), >0 decreases salinity
123	oceSflux net surface Salt flux into the ocean (+=down), >0 increases salinity
124	surForcT model surface forcing for Temperature, >0 increases theta
125	surForcS model surface forcing for Salinity, >0 increases salinity
126
127	--------------------------------------------------------------------------
128	Relation between surForcT,surForcS and others surface forcing diagnostics:
129	[x] = average of model variable "x" over the diagnostic time interval
130
131	a) if useRealFreshWaterFlux=F or (nonlinFreeSurf=0 & usingZCoords=T)
132	surForcT = oceQnet + TRELAX - oceQsw
133	surForcS = oceSflux + SRELAX - [PmEpR*So]
134	(with So = local Sea-Surface Salinity (SSS) if convertFW2Salt=-1
135	and So = convertFW2Salt otherwise)
136	oceFWflx = [PmEpR]
137	TFLUX = surForcT + oceQsw + oceFreez
138	SFLUX = surForcS
139
140	b) if useRealFreshWaterFlux=T & (nonlinFreeSurf>0 or usingPCoords=T),
141	In general:
142	surForcT = oceQnet + TRELAX - oceQsw + [T_dilution_effect]*Cp
143	surForcS = oceSflux + SRELAX + [S_dilution_effect]
144	where T_dilution_effect = PmEpR*( temp_EvPrRn - SST )
145	and S_dilution_effect = PmEpR*( salt_EvPrRn - SSS )
146	oceFWflx = [PmEpR]
147	TFLUX = surForcT + oceQsw + oceFreez + [PmEpRSST]Cp
148	SFLUX = surForcS + [PmEpR*SSS]
149
150	And with the default value: salt_EvPrRn=0. & temp_EvPrRn=UNSET_RL
151	(=> no dilution effect on Temp.):
152	surForcT = oceQnet + TRELAX - oceQsw
153	surForcS = oceSflux + SRELAX - [PmEpR*SSS]
154
155	Notes:
156	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
158	EmPmR is still a volume flux per surface area [units: m/s].
159	2) With Linear FreeSurf, there is a small loss of heat/salt/tracer at the
160	surface (d/dt(Eta) inconsistent with fixed surf grid cell thickness:
161	a) if linFSConserveTr is set to true (file "data"), then the model
162	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.