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c $Header: /u/gcmpack/models/MITgcmUV/pkg/exf/exf_getffields.F,v 1.1 2001/05/14 22:08:40 heimbach Exp $ |
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|
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#include "EXF_CPPOPTIONS.h" |
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|
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subroutine exf_GetFFields( |
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I mycurrenttime, |
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I mycurrentiter, |
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I mythid |
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& ) |
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|
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c ================================================================== |
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c SUBROUTINE exf_GetFFields |
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c ================================================================== |
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c |
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c o Get the surface fluxes either from file or as derived from bulk |
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c formulae that use the atmospheric state. |
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c |
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c The calculation of the bulk surface fluxes has been adapted from |
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c the NCOM model which uses the formulae given in Large and Pond |
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c (1981 & 1982 ) |
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c |
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c |
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c Header taken from NCOM version: ncom1.4.1 |
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c ----------------------------------------- |
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c |
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c Following procedures and coefficients in Large and Pond |
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c (1981 ; 1982) |
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c |
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c Output: Bulk estimates of the turbulent surface fluxes. |
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c ------- |
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c |
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c hs - sensible heat flux (W/m^2), into ocean |
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c hl - latent heat flux (W/m^2), into ocean |
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c |
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c Input: |
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c ------ |
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c |
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c us - mean wind speed (m/s) at height hu (m) |
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c th - mean air temperature (K) at height ht (m) |
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c qh - mean air humidity (kg/kg) at height hq (m) |
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c sst - sea surface temperature (K) |
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c tk0 - Kelvin temperature at 0 Celsius (K) |
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c |
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c Assume 1) a neutral 10m drag coefficient = |
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c |
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c cdn = .0027/u10 + .000142 + .0000764 u10 |
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c |
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c 2) a neutral 10m stanton number = |
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c |
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c ctn = .0327 sqrt(cdn), unstable |
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c ctn = .0180 sqrt(cdn), stable |
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c |
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c 3) a neutral 10m dalton number = |
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c |
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c cen = .0346 sqrt(cdn) |
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c |
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c 4) the saturation humidity of air at |
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c |
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c t(k) = exf_BulkqSat(t) (kg/m^3) |
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c |
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c Note: 1) here, tstar = <wt>/u*, and qstar = <wq>/u*. |
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c 2) wind speeds should all be above a minimum speed, |
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c say 0.5 m/s. |
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c 3) with optional iteration loop, niter=3, should suffice. |
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c 4) this version is for analyses inputs with hu = 10m and |
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c ht = hq. |
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c 5) sst enters in Celsius. |
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c |
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c ------------------------------------ |
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c |
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c By setting CPP options in the header file *EXF_CPPOPTIONS.h* it |
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c is possible to combine data sets in four different ways: |
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c |
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c The following options are available: |
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c |
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c ALLOW_ATM_TEMP (UAT) |
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c ALLOW_ATM_WIND (UAW) |
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c |
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c |
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c UAT | UAW | action |
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c ---------------------------------------------------- |
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c undefined | undefined | Use surface fluxes. |
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c undefined | defined | Assume cdn(u) given to |
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c | | infer the wind stress. |
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c defined | undefined | Compute wind field from |
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c | | given stress assuming a |
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c | | linear relation. |
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c defined | defined | Use the bulk formulae. |
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c ---------------------------------------------------- |
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c |
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c Implementations of the bulk formulae exist for the follwing |
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c versions of the MITgcm: |
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c |
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c MITgcm : Patrick Heimbach |
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c MITgcmUV: Christian Eckert |
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c |
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c started: Christian Eckert eckert@mit.edu 27-Aug-1999 |
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c |
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c changed: Christian Eckert eckert@mit.edu 14-Jan-2000 |
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c |
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c - restructured the original version in order to have a |
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c better interface to the MITgcmUV. |
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c |
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c Christian Eckert eckert@mit.edu 12-Feb-2000 |
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c |
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c - Changed Routine names (package prefix: exf_) |
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c |
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c Patrick Heimbach, heimbach@mit.edu 04-May-2000 |
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c |
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c - changed the handling of precip and sflux with respect |
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c to CPP options ALLOW_BULKFORMULAE and ALLOW_ATM_TEMP |
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c |
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c - included some CPP flags ALLOW_BULKFORMULAE to make |
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c sure ALLOW_ATM_TEMP, ALLOW_ATM_WIND are used only in |
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c conjunction with defined ALLOW_BULKFORMULAE |
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c |
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c - statement functions discarded |
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c |
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c Ralf.Giering@FastOpt.de 25-Mai-2000 |
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c |
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c - total rewrite using new subroutines |
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c |
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c ================================================================== |
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c SUBROUTINE exf_GetFFields |
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c ================================================================== |
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|
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implicit none |
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|
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c == global variables == |
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|
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#include "EEPARAMS.h" |
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#include "SIZE.h" |
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#include "PARAMS.h" |
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#include "DYNVARS.h" |
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#include "GRID.h" |
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|
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#include "exf_fields.h" |
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#include "exf_constants.h" |
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|
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c == routine arguments == |
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|
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integer mythid |
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integer mycurrentiter |
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_RL mycurrenttime |
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|
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c == local variables == |
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|
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integer bi,bj |
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integer i,j,k |
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|
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#ifdef ALLOW_BULKFORMULAE |
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|
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#ifdef ALLOW_ATM_TEMP |
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integer iter |
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_RL aln |
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_RL delq |
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_RL deltap |
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_RL hqol |
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_RL htol |
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_RL huol |
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_RL psimh |
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_RL psixh |
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_RL qstar |
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_RL rd |
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_RL re |
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_RL rdn |
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_RL rh |
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_RL ssq |
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_RL stable |
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_RL tau |
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_RL tstar |
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_RL t0 |
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_RL ustar |
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_RL uzn |
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_RL xsq |
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_RL x |
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_RL evap(1-olx:snx+olx,1-oly:sny+oly,nsx,nsy) |
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#endif /* ALLOW_ATM_TEMP */ |
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|
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_RL us |
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_RL cw |
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_RL sw |
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_RL sh |
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_RL hs(1-olx:snx+olx,1-oly:sny+oly,nsx,nsy) |
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_RL hl(1-olx:snx+olx,1-oly:sny+oly,nsx,nsy) |
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_RL hfl |
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|
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#endif /* ALLOW_BULKFORMULAE */ |
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|
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c == external functions == |
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|
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integer ilnblnk |
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external ilnblnk |
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|
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#ifdef ALLOW_BULKFORMULAE |
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_RL exf_BulkqSat |
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external exf_BulkqSat |
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_RL exf_BulkCdn |
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external exf_BulkCdn |
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_RL exf_BulkRhn |
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external exf_BulkRhn |
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#endif /* ALLOW_BULKFORMULAE */ |
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|
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c == end of interface == |
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|
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c determine forcing field records |
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|
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#ifdef ALLOW_BULKFORMULAE |
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|
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c Determine where we are in time and set counters, flags and |
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c the linear interpolation factors accordingly. |
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#ifdef ALLOW_ATM_TEMP |
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c Atmospheric temperature. |
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call exf_set_atemp( atemp |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Atmospheric humidity. |
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call exf_set_aqh( aqh |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Net long wave radiative flux. |
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call exf_set_lwflux( lwflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Net short wave radiative flux. |
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call exf_set_swflux( swflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Precipitation. |
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call exf_set_precip( precip |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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aln = log(ht/zref) |
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|
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#else |
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|
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c Atmospheric heat flux. |
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call exf_set_hflux( hflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Salt flux. |
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call exf_set_sflux( sflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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#ifdef ALLOW_KPP |
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c Net short wave radiative flux. |
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call exf_set_swflux( swflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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#endif /* ALLOW_KPP */ |
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|
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#endif /* ALLOW_ATM_TEMP */ |
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|
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#ifdef ALLOW_ATM_WIND |
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c Zonal wind. |
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call exf_set_uwind( uwind |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Meridional wind. |
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call exf_set_vwind( vwind |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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#else |
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c Zonal wind stress. |
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call exf_set_ustress( ustress |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Meridional wind stress. |
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call exf_set_vstress( vstress |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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#endif /* ALLOW_ATM_WIND */ |
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|
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#else /* ALLOW_BULKFORMULAE undefined */ |
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c Atmospheric heat flux. |
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call exf_set_hflux( hflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Salt flux. |
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call exf_set_sflux( sflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Zonal wind stress. |
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call exf_set_ustress( ustress |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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c Meridional wind stress. |
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call exf_set_vstress( vstress |
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& , mycurrenttime, mycurrentiter, mythid ) |
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|
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#ifdef ALLOW_KPP |
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c Net short wave radiative flux. |
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call exf_set_swflux( swflux |
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& , mycurrenttime, mycurrentiter, mythid ) |
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#endif /* ALLOW_KPP */ |
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|
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#endif /* ALLOW_BULKFORMULAE */ |
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|
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c Loop over tiles. |
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do bj = mybylo(mythid),mybyhi(mythid) |
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do bi = mybxlo(mythid),mybxhi(mythid) |
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k = 1 |
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|
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do j = 1-oly,sny+oly |
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do i = 1-olx,snx+olx |
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|
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#ifdef ALLOW_BULKFORMULAE |
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|
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c Compute the turbulent surface fluxes. |
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c (Bulk formulae estimates) |
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|
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#ifdef ALLOW_ATM_WIND |
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c Wind speed and direction. |
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us = sqrt(uwind(i,j,bi,bj)*uwind(i,j,bi,bj) + |
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& vwind(i,j,bi,bj)*vwind(i,j,bi,bj)) |
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if ( us .ne. 0. _d 0 ) then |
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cw = uwind(i,j,bi,bj)/us |
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sw = vwind(i,j,bi,bj)/us |
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else |
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cw = 0. _d 0 |
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sw = 0. _d 0 |
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endif |
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sh = max(us,umin) |
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#else |
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#ifdef ALLOW_ATM_TEMP |
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|
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c The variables us, sh and rdn have to be computed from given |
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c wind stresses inverting relationship for neutral drag coeff. |
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c cdn. |
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c The inversion is based on linear and quadratic form of |
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c cdn(umps); ustar can be directly computed from stress; |
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|
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ustar = sqrt(ustress(i,j,bi,bj)*ustress(i,j,bi,bj) + |
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& vstress(i,j,bi,bj)*vstress(i,j,bi,bj))/ |
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& atmrho |
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cw = ustress(i,j,bi,bj)/ustar |
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sw = ustress(i,j,bi,bj)/ustar |
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|
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if ( ustar .eq. 0. _d 0 ) then |
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us = 0. _d 0 |
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else if ( ustar .lt. ustofu11 ) then |
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tmp1 = -cquadrag_2/cquadrag_1/2 |
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tmp2 = sqrt(tmp1*tmp1 + ustar*ustar/cquadrag_1) |
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us = sqrt(tmp1 + tmp2) |
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else |
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tmp3 = clindrag_2/clindrag_1/3 |
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tmp4 = ustar*ustar/clindrag_1/2 - tmp3**3 |
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tmp5 = sqrt(ustar*ustar/clindrag_1* |
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& (ustar*ustar/clindrag_1/4 - tmp3**3)) |
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us = (tmp4 + tmp5)**(1/3) + |
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& tmp3**2 * (tmp4 + tmp5)**(-1/3) - tmp3 |
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endif |
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|
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if ( us .ne. 0 ) then |
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rdn = ustar/us |
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else |
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rdn = 0. _d 0 |
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end if |
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|
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sh = max(us,umin) |
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#endif /* ALLOW_ATM_TEMP */ |
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#endif /* ALLOW_ATM_WIND */ |
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|
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#ifdef ALLOW_ATM_TEMP |
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c Initial guess: z/l=0.0; hu=ht=hq=z |
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c Iterations: converge on z/l and hence the fluxes. |
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c t0 : virtual temperature (K) |
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c ssq : sea surface humidity (kg/kg) |
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c deltap : potential temperature diff (K) |
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|
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if ( atemp(i,j,bi,bj) .ne. 0. _d 0 ) then |
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t0 = atemp(i,j,bi,bj)* |
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& (exf_one + humid_fac*aqh(i,j,bi,bj)) |
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ssq = saltsat* |
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& exf_BulkqSat(theta(i,j,1,bi,bj) + cen2kel)/ |
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& atmrho |
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deltap = atemp(i,j,bi,bj) + gamma_blk*ht - |
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& theta(i,j,1,bi,bj) - cen2kel |
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delq = aqh(i,j,bi,bj) - ssq |
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stable = exf_half + sign(exf_half, deltap) |
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rdn = sqrt(exf_BulkCdn(sh)) |
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ustar = rdn*sh |
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tstar = exf_BulkRhn(stable)*deltap |
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qstar = cdalton*delq |
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|
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do iter = 1,niter_bulk |
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|
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huol = czol*(tstar/t0 + |
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& qstar/(exf_one/humid_fac+aqh(i,j,bi,bj)))/ |
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& ustar**2 |
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huol = max(huol,zolmin) |
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stable = exf_half + sign(exf_half, huol) |
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htol = huol*ht/hu |
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hqol = huol*hq/hu |
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|
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c Evaluate all stability functions assuming hq = ht. |
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xsq = max(sqrt(abs(exf_one - 16.*huol)),exf_one) |
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x = sqrt(xsq) |
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psimh = -psim_fac*huol*stable + |
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& (exf_one - stable)* |
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& log((exf_one + x*(exf_two + x))* |
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& (exf_one + xsq)/8.) - exf_two*atan(x) + |
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& pi*exf_half |
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xsq = max(sqrt(abs(exf_one - 16.*htol)),exf_one) |
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psixh = -psim_fac*htol*stable + (exf_one - stable)* |
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& exf_two*log((exf_one + xsq)/exf_two) |
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|
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c Shift wind speed using old coefficient |
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c rd = rdn/(exf_one + rdn/karman*(log(hu/zref) - psimh) ) |
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rd = rdn/(exf_one - rdn/karman*psimh ) |
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uzn = max(sh*rd/rdn, umin) |
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|
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c Update the transfer coefficients at 10 meters |
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c and neutral stability. |
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rdn = sqrt(exf_BulkCdn(uzn)) |
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|
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c Shift all coefficients to the measurement height |
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c and stability. |
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c rd = rdn/(exf_one + rdn/karman*(log(hu/zref) - psimh)) |
420 |
rd = rdn/(exf_one - rdn/karman*psimh) |
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rh = exf_BulkRhn(stable)/(exf_one + |
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& exf_BulkRhn(stable)/ |
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& karman*(aln - psixh)) |
424 |
re = cdalton/(exf_one + cdalton/karman*(aln - psixh)) |
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|
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c Update ustar, tstar, qstar using updated, shifted |
427 |
c coefficients. |
428 |
ustar = rd*sh |
429 |
qstar = re*delq |
430 |
tstar = rh*deltap |
431 |
|
432 |
enddo |
433 |
|
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tau = atmrho*ustar**2 |
435 |
tau = tau*us/sh |
436 |
hs(i,j,bi,bj) = atmcp*tau*tstar/ustar |
437 |
hl(i,j,bi,bj) = flamb*tau*qstar/ustar |
438 |
|
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evap(i,j,bi,bj) = tau*qstar/ustar |
440 |
|
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ustress(i,j,bi,bj) = tau*cw |
442 |
vstress(i,j,bi,bj) = tau*sw |
443 |
ce hflux(i,j,bi,bj) = atmcp*tau*tstar/ustar + |
444 |
ce & flamb*tau*qstar/ustar |
445 |
else |
446 |
ustress(i,j,bi,bj) = 0. _d 0 |
447 |
vstress(i,j,bi,bj) = 0. _d 0 |
448 |
hflux (i,j,bi,bj) = 0. _d 0 |
449 |
hs(i,j,bi,bj) = 0. _d 0 |
450 |
hl(i,j,bi,bj) = 0. _d 0 |
451 |
endif |
452 |
|
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#else |
454 |
#ifdef ALLOW_ATM_WIND |
455 |
ustress(i,j,bi,bj) = atmrho*exf_BulkCdn(sh)*us* |
456 |
& uwind(i,j,bi,bj) |
457 |
vstress(i,j,bi,bj) = atmrho*exf_BulkCdn(sh)*us* |
458 |
& vwind(i,j,bi,bj) |
459 |
#endif /* ALLOW_ATM_WIND */ |
460 |
#endif /* ALLOW_ATM_TEMP */ |
461 |
enddo |
462 |
enddo |
463 |
enddo |
464 |
enddo |
465 |
|
466 |
c Add all contributions. |
467 |
k = 1 |
468 |
do bj = mybylo(mythid),mybyhi(mythid) |
469 |
do bi = mybxlo(mythid),mybxhi(mythid) |
470 |
do j = 1,sny |
471 |
do i = 1,snx |
472 |
c Net surface heat flux. |
473 |
#ifdef ALLOW_ATM_TEMP |
474 |
hfl = 0. _d 0 |
475 |
hfl = hfl - hs(i,j,bi,bj) |
476 |
hfl = hfl - hl(i,j,bi,bj) |
477 |
hfl = hfl + lwflux(i,j,bi,bj) |
478 |
#ifndef ALLOW_KPP |
479 |
hfl = hfl + swflux(i,j,bi,bj) |
480 |
#endif /* ALLOW_KPP undef */ |
481 |
c Heat flux: |
482 |
hflux(i,j,bi,bj) = hfl*maskc(i,j,k,bi,bj) |
483 |
c Salt flux from Precipitation and Evaporation. |
484 |
sflux(i,j,bi,bj) = precip(i,j,bi,bj) - evap(i,j,bi,bj) |
485 |
#endif /* ALLOW_ATM_TEMP */ |
486 |
|
487 |
#else |
488 |
hflux(i,j,bi,bj) = hflux(i,j,bi,bj)*maskc(i,j,k,bi,bj) |
489 |
sflux(i,j,bi,bj) = sflux(i,j,bi,bj)*maskc(i,j,k,bi,bj) |
490 |
#endif /* ALLOW_BULKFORMULAE */ |
491 |
enddo |
492 |
enddo |
493 |
enddo |
494 |
enddo |
495 |
|
496 |
c Update the tile edges. |
497 |
_EXCH_XY_R8(hflux, mythid) |
498 |
_EXCH_XY_R8(sflux, mythid) |
499 |
_EXCH_XY_R8(ustress, mythid) |
500 |
_EXCH_XY_R8(vstress, mythid) |
501 |
|
502 |
#ifdef ALLOW_KPP |
503 |
_EXCH_XY_R8(swflux, mythid) |
504 |
#endif /* ALLOW_KPP */ |
505 |
|
506 |
end |