1 | MODULE trasbc |
---|
2 | !!====================================================================== |
---|
3 | !! *** MODULE trasbc *** |
---|
4 | !! Ocean active tracers: surface boundary condition |
---|
5 | !!====================================================================== |
---|
6 | !! History : OPA ! 1998-10 (G. Madec, G. Roullet, M. Imbard) Original code |
---|
7 | !! 8.2 ! 2001-02 (D. Ludicone) sea ice and free surface |
---|
8 | !! NEMO 1.0 ! 2002-06 (G. Madec) F90: Free form and module |
---|
9 | !! 3.3 ! 2010-05 (Y. Aksenov G. Madec) salt flux + heat associated with emp |
---|
10 | !!---------------------------------------------------------------------- |
---|
11 | |
---|
12 | !!---------------------------------------------------------------------- |
---|
13 | !! tra_sbc : update the tracer trend at ocean surface |
---|
14 | !!---------------------------------------------------------------------- |
---|
15 | USE oce ! ocean dynamics and active tracers |
---|
16 | USE sbc_oce ! surface boundary condition: ocean |
---|
17 | USE dom_oce ! ocean space domain variables |
---|
18 | USE phycst ! physical constant |
---|
19 | USE traqsr ! solar radiation penetration |
---|
20 | USE trdmod ! ocean trends |
---|
21 | USE trdmod_oce ! ocean variables trends |
---|
22 | USE in_out_manager ! I/O manager |
---|
23 | USE prtctl ! Print control |
---|
24 | |
---|
25 | IMPLICIT NONE |
---|
26 | PRIVATE |
---|
27 | |
---|
28 | PUBLIC tra_sbc ! routine called by step.F90 |
---|
29 | |
---|
30 | !! * Substitutions |
---|
31 | # include "domzgr_substitute.h90" |
---|
32 | # include "vectopt_loop_substitute.h90" |
---|
33 | !!---------------------------------------------------------------------- |
---|
34 | !! NEMO/OPA 3.3 , LOCEAN-IPSL (2010) |
---|
35 | !! $Id$ |
---|
36 | !! Software governed by the CeCILL licence (modipsl/doc/NEMO_CeCILL.txt) |
---|
37 | !!---------------------------------------------------------------------- |
---|
38 | |
---|
39 | CONTAINS |
---|
40 | |
---|
41 | SUBROUTINE tra_sbc ( kt ) |
---|
42 | !!---------------------------------------------------------------------- |
---|
43 | !! *** ROUTINE tra_sbc *** |
---|
44 | !! |
---|
45 | !! ** Purpose : Compute the tracer surface boundary condition trend of |
---|
46 | !! (flux through the interface, concentration/dilution effect) |
---|
47 | !! and add it to the general trend of tracer equations. |
---|
48 | !! |
---|
49 | !! ** Method : |
---|
50 | !! Following Roullet and Madec (2000), the air-sea flux can be divided |
---|
51 | !! into three effects: (1) Fext, external forcing; |
---|
52 | !! (2) Fwi, concentration/dilution effect due to water exchanged |
---|
53 | !! at the surface by evaporation, precipitations and runoff (E-P-R); |
---|
54 | !! (3) Fwe, tracer carried with the water that is exchanged. |
---|
55 | !! - salinity : salt flux only due to freezing/melting |
---|
56 | !! sa = sa + fsalt / rau0 / e3t for k=1 |
---|
57 | !! |
---|
58 | !! Fext, flux through the air-sea interface for temperature and salt: |
---|
59 | !! - temperature : heat flux q (w/m2). If penetrative solar |
---|
60 | !! radiation q is only the non solar part of the heat flux, the |
---|
61 | !! solar part is added in traqsr.F routine. |
---|
62 | !! ta = ta + q /(rau0 rcp e3t) for k=1 |
---|
63 | !! - salinity : no salt flux |
---|
64 | !! |
---|
65 | !! The formulation for Fwb and Fwi vary according to the free |
---|
66 | !! surface formulation (linear or variable volume). |
---|
67 | !! * Linear free surface |
---|
68 | !! The surface freshwater flux modifies the ocean volume |
---|
69 | !! and thus the concentration of a tracer and the temperature. |
---|
70 | !! First order of the effect of surface freshwater exchange |
---|
71 | !! for salinity, it can be neglected on temperature (especially |
---|
72 | !! as the temperature of precipitations and runoffs is usually |
---|
73 | !! unknown). |
---|
74 | !! - temperature : we assume that the temperature of both |
---|
75 | !! precipitations and runoffs is equal to the SST, thus there |
---|
76 | !! is no additional flux since in this case, the concentration |
---|
77 | !! dilution effect is balanced by the net heat flux associated |
---|
78 | !! to the freshwater exchange (Fwe+Fwi=0): |
---|
79 | !! (Tp P - Te E) + SST (P-E) = 0 when Tp=Te=SST |
---|
80 | !! - salinity : evaporation, precipitation and runoff |
---|
81 | !! water has a zero salinity but there is a salt flux due to |
---|
82 | !! freezing/melting, thus: |
---|
83 | !! sa = sa + emp * sn / rau0 / e3t for k=1 |
---|
84 | !! + fsalt / rau0 / e3t |
---|
85 | !! where emp, the surface freshwater budget (evaporation minus |
---|
86 | !! precipitation minus runoff) given in kg/m2/s is divided |
---|
87 | !! by rau0 = 1020 kg/m3 (density of sea water) to obtain m/s. |
---|
88 | !! Note: even though Fwe does not appear explicitly for |
---|
89 | !! temperature in this routine, the heat carried by the water |
---|
90 | !! exchanged through the surface is part of the total heat flux |
---|
91 | !! forcing and must be taken into account in the global heat |
---|
92 | !! balance). |
---|
93 | !! * nonlinear free surface (variable volume, lk_vvl) |
---|
94 | !! contrary to the linear free surface case, Fwi is properly |
---|
95 | !! taken into account by using the true layer thicknesses to |
---|
96 | !! calculate tracer content and advection. There is no need to |
---|
97 | !! deal with it in this routine. |
---|
98 | !! - temperature: Fwe=SST (P-E+R) is added to Fext. |
---|
99 | !! - salinity: Fwe sa = sa + fsalt / rau0 / e3t. |
---|
100 | !! |
---|
101 | !! ** Action : - Update the 1st level of (ta,sa) with the trend associated |
---|
102 | !! with the tracer surface boundary condition |
---|
103 | !! - save the trend it in ttrd ('key_trdtra') |
---|
104 | !!---------------------------------------------------------------------- |
---|
105 | USE oce, ONLY : ztrdt => ua ! use ua as 3D workspace |
---|
106 | USE oce, ONLY : ztrds => va ! - va - - |
---|
107 | !! |
---|
108 | INTEGER, INTENT(in) :: kt ! ocean time-step index |
---|
109 | !! |
---|
110 | INTEGER :: ji, jj ! dummy loop indices |
---|
111 | REAL(wp) :: z1_e3t_rau0 ! local scalars |
---|
112 | !!---------------------------------------------------------------------- |
---|
113 | |
---|
114 | IF( kt == nit000 ) THEN |
---|
115 | IF(lwp) WRITE(numout,*) |
---|
116 | IF(lwp) WRITE(numout,*) 'tra_sbc : TRAcer Surface Boundary Condition' |
---|
117 | IF(lwp) WRITE(numout,*) '~~~~~~~ ' |
---|
118 | ENDIF |
---|
119 | |
---|
120 | IF( l_trdtra ) THEN ! Save ta and sa trends |
---|
121 | ztrdt(:,:,:) = ta(:,:,:) |
---|
122 | ztrds(:,:,:) = sa(:,:,:) |
---|
123 | ENDIF |
---|
124 | |
---|
125 | !!gm useless staff ??? |
---|
126 | IF( .NOT.ln_traqsr ) qsr(:,:) = 0.e0 ! no solar radiation penetration |
---|
127 | !!gm |
---|
128 | |
---|
129 | |
---|
130 | IF( lk_vvl ) THEN ! Variable Volume Layers case ===>> heat content of mass flux in qns |
---|
131 | DO jj = 2, jpj |
---|
132 | DO ji = fs_2, fs_jpim1 ! vector opt. |
---|
133 | z1_e3t_rau0 = 1./ ( fse3t(ji,jj,1) * rau0 ) |
---|
134 | ta(ji,jj,1) = ta(ji,jj,1) + z1_e3t_rau0 * qns (ji,jj) * r1_rcp ! non solar heat flux |
---|
135 | sa(ji,jj,1) = sa(ji,jj,1) + z1_e3t_rau0 * emps(ji,jj) ! salt flux (freezing/melting) |
---|
136 | END DO |
---|
137 | END DO |
---|
138 | ! |
---|
139 | ELSE ! Constant Volume layers case ===>> Concentration dillution effect |
---|
140 | DO jj = 2, jpj |
---|
141 | DO ji = fs_2, fs_jpim1 ! vector opt. |
---|
142 | z1_e3t_rau0 = 1./ ( fse3t(ji,jj,1) * rau0 ) |
---|
143 | ta(ji,jj,1) = ta(ji,jj,1) + z1_e3t_rau0 * ( qns (ji,jj) * r1_rcp & ! non solar heat flux |
---|
144 | & + emp (ji,jj) * tn(ji,jj,1) ) ! concent./dilut. effect |
---|
145 | sa(ji,jj,1) = sa(ji,jj,1) + z1_e3t_rau0 * ( emps(ji,jj) & ! salt flux (freezing/melting) |
---|
146 | & + emp (ji,jj) * sn(ji,jj,1) ) ! concent./dilut. effect |
---|
147 | END DO |
---|
148 | END DO |
---|
149 | ENDIF |
---|
150 | |
---|
151 | IF( l_trdtra ) THEN ! save the sbc trends for diagnostic |
---|
152 | ztrdt(:,:,:) = ta(:,:,:) - ztrdt(:,:,:) |
---|
153 | ztrds(:,:,:) = sa(:,:,:) - ztrds(:,:,:) |
---|
154 | CALL trd_mod(ztrdt, ztrds, jptra_trd_nsr, 'TRA', kt) |
---|
155 | ENDIF |
---|
156 | ! |
---|
157 | IF(ln_ctl) CALL prt_ctl( tab3d_1=ta, clinfo1=' sbc - Ta: ', mask1=tmask, & |
---|
158 | & tab3d_2=sa, clinfo2= ' Sa: ', mask2=tmask, clinfo3='tra' ) |
---|
159 | ! |
---|
160 | END SUBROUTINE tra_sbc |
---|
161 | |
---|
162 | !!====================================================================== |
---|
163 | END MODULE trasbc |
---|