Changeset 664 for trunk/NEMO/OPA_SRC

Timestamp:

2007-05-25T18:14:37+02:00 (17 years ago)

Author:

opalod

Message:

RB:nemo_v2_bugfix_040: add correct comments to trasbc

File:

• trunk/NEMO/OPA_SRC/TRA/trasbc.F90 (modified) (2 diffs)

trunk/NEMO/OPA_SRC/TRA/trasbc.F90

@@ -47 +47 @@
       !!
       !! ** Method :
-      !!      * flux through the air-sea interface:
+      !!      Following Roullet and Madec (2000), the air-sea flux can be divided 
+      !!      into three effects: (1) Fext, external forcing; 
+      !!      (2) Fwi, concentration/dilution effect due to water exchanged 
+      !!         at the surface by evaporation, precipitations and runoff (E-P-R); 
+      !!      (3) Fwe, tracer carried with the water that is exchanged. 
+      !!
+      !!      Fext, flux through the air-sea interface for temperature and salt: 
       !!            - temperature : heat flux q (w/m2). If penetrative solar
       !!         radiation q is only the non solar part of the heat flux, the
@@ -53 +59 @@
       !!            ta = ta + q /(rau0 rcp e3t)  for k=1
       !!            - salinity    : no salt flux
-      !!      * concentration/dilution effect:
-      !!            The surface freshwater flux modify the ocean volume
+      !!
+      !!      The formulation for Fwb and Fwi vary according to the free 
+      !!      surface formulation (linear or variable volume). 
+      !!      * Linear free surface
+      !!            The surface freshwater flux modifies the ocean volume
       !!         and thus the concentration of a tracer and the temperature.
       !!         First order of the effect of surface freshwater exchange 
       !!         for salinity, it can be neglected on temperature (especially
-      !!         as the temparature of precipitations and runoffs is usually
-      !!         unknown.
+      !!         as the temperature of precipitations and runoffs is usually
+      !!         unknown).
       !!            - temperature : we assume that the temperature of both
       !!         precipitations and runoffs is equal to the SST, thus there
       !!         is no additional flux since in this case, the concentration
       !!         dilution effect is balanced by the net heat flux associated
-      !!         to the freshwater exchange:
-      !!            (Tp P - Te E) + STT (P-E) = 0 when Tp=Te=SST
+      !!         to the freshwater exchange (Fwe+Fwi=0):
+      !!            (Tp P - Te E) + SST (P-E) = 0 when Tp=Te=SST
       !!            - salinity    : evaporation, precipitation and runoff
-      !!         water has a zero salinity, thus
+      !!         water has a zero salinity (Fwe=0), thus only Fwi remains:
       !!            sa = sa + emp * sn / e3t   for k=1
       !!         where emp, the surface freshwater budget (evaporation minus
       !!         precipitation minus runoff) given in kg/m2/s is divided
-      !!         by 1000 kg/m3 (density of plain water) to obtain m/s.
+      !!         by 1000 kg/m3 (density of plain water) to obtain m/s.    
+      !!         Note: even though Fwe does not appear explicitly for 
+      !!         temperature in this routine, the heat carried by the water
+      !!         exchanged through the surface is part of the total heat flux
+      !!         forcing and must be taken into account in the global heat
+      !!         balance).
+      !!      * nonlinear free surface (variable volume, lk_vvl)
+      !!         contrary to the linear free surface case, Fwi is properly 
+      !!         taken into account by using the true layer thicknesses to       
+      !!         calculate tracer content and advection. There is no need to 
+      !!         deal with it in this routine.
+      !!           - temperature: Fwe=SST (P-E+R) is added to Fext.
+      !!           - salinity:  Fwe = 0, there is no surface flux of salt.
       !!
       !! ** Action  : - Update the 1st level of (ta,sa) with the trend associated