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C $Header: /u/u3/gcmpack/MITgcm/pkg/sbo/sbo_calc.F,v 1.3.4.1 2003/10/02 18:18:33 adcroft Exp $ |
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C $Name: $ |
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|
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#include "SBO_OPTIONS.h" |
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|
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SUBROUTINE SBO_CALC( myCurrentTime, myIter, myThid ) |
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C /==========================================================\ |
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C | SUBROUTINE SBO_CALC | |
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C | o Do SBO diagnostic output. | |
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C |==========================================================| |
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C | NOTE: The following subtleties are ignored for time | |
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C | being but may need revisiting at some point in time. | |
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C | 1) The model is volume-preserving and Boussinesq so | |
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C | quantities like oceanic mass need to be interpreted | |
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C | with some care. | |
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C | 2) The sea surface height variable etaN lags other | |
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C | prognostic variables by half a time step. This lag | |
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C | is ignored in SBO computations. | |
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C | 3) Density is computed using function SBO_RHO which is | |
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C | not exaclty equivalent to the model s FIND_RHO. | |
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C \==========================================================/ |
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IMPLICIT NONE |
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|
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c======================================================================= |
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c |
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c Written by Richard Gross (Richard.Gross@jpl.nasa.gov) |
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c June 10, 2001: Modified for online computations in MIT GCM UV |
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c by Dimitris Menemenlis (Menemenlis@jpl.nasa.gov) |
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c |
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c Purpose |
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c calc_sbo calculates the core products of the IERS Special Bureau |
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c for the Oceans including oceanic mass, center-of-mass, angular |
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c momentum, and bottom pressure. |
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c |
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c Usage |
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c 1. calc_sbo must be called, and the results saved, at each time step |
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c in order to create a time series of the IERS SBO core products |
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c 2. it is suggested that after the time series have been generated |
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c and before saving the results to a file, time-mean values be |
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c computed and removed from all of the calculated core products |
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c and that the mean values be reported along with the demeaned |
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c time series |
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c |
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c Availability |
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c ftp://euler.jpl.nasa.gov/sbo/software/calc_sbo.f |
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c |
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c Reference |
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c Gross, R. S., F. O. Bryan, Y. Chao, J. O. Dickey, S. L. Marcus, |
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c R. M. Ponte, and R. Tokmakian, The IERS Special Bureau for the |
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c Oceans, in IERS Technical Note on the IERS Global Geophysical |
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c Fluids Center, edited by B. Chao, in press, Observatoire de Paris, |
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c Paris, France, 2000. |
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c |
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c Required inputs |
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c gridded values of horizontal velocity (u,v), temperature, |
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c salinity, and sea surface height along with the latitude, |
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c and longitude of the grid points and the thicknesses of the |
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c vertical layers |
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c |
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c External routines called by calc_sbo |
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c real function rho1(s, t) |
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c returns density of sea water given salinity s and temperature t |
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c (a default version of rho1 has been included with calc_sbo, |
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c however in general this should be replaced by a function that |
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c returns the density of the model ocean so that the same density |
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c as the model s is used to compute the sbo products) |
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c |
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c Assumptions |
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c 1. the input velocity, temperature, salinity, and sea surface |
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c height fields are assumed to be defined on the same grid |
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c 2. the horizontal grid is assumed to be equally spaced in |
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c latitude and longitude |
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c 3. land is flagged in the input quantities by a salinity or |
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c temperature value greater than or equal to 999.99 |
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c 4. input quantities are assumed to have the following units: |
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c salinity (s) parts per thousand |
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c temperature (t) degrees centigrade |
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c eastwards velocity (u) centimeters per second |
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c northwards velocity (v) centimeters per second |
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c sea surface height (ssh) meters |
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c latitude of grid point degrees N |
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c longitude of grid point degrees E |
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c thickness of layer meters |
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c 5. input quantities are passed to calc_sbo via common blocks |
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c /ogcm/ and /vgrid/ |
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c 6. land is flagged in the output ocean-bottom pressure (obp) |
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c by a value of -999.99 |
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c 7. calulated products have the units: |
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c mass of oceans (mass) kilograms (kg) |
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c center-of-mass of oceans (com) meters (m) |
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c oceanic angular momentum (oam) kg-m**2/second |
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c ocean-bottom pressure (obp) Pascals (Newton/m**2) |
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c 8. calculated products are passed out of calc_sbo via common |
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c block /sbo/ |
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c 9. the sea surface height layer is assumed to have the same |
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c velocity, temperature, and salinity as the first depth layer |
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c |
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c For questions regarding calc_sbo or the IERS SBO, please contact: |
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c Richard Gross Richard.Gross@jpl.nasa.gov |
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c Jet Propulsion Laboratory ph. +1 818-354-4010 |
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c Mail Stop 238-332 fax +1 818-393-6890 |
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c 4800 Oak Grove Drive |
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c Pasadena, Ca 91109-8099 |
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c USA |
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c |
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c======================================================================= |
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|
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C === Global variables === |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "PARAMS.h" |
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#include "GRID.h" |
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#include "DYNVARS.h" |
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#include "CG2D.h" |
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#include "SBO.h" |
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|
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C == Routine arguments == |
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C myCurrentTime - Current time of simulation ( s ) |
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C myIter - Iteration number |
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C myThid - Number of this instance of SBO_CALC |
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_RL myCurrentTime |
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INTEGER myIter, myThid |
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|
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#ifdef ALLOW_SBO |
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|
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c external function called by calc_sbo |
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c returns density of sea water |
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_RL sbo_rho |
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|
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c internal variables |
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c bi, bj - array indices |
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c I - index over longitude grid points |
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c J - index over latitude grid points |
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c K - index over layers |
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c lat - latitude of grid point (radians) |
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c lat_deg - latitude of grid point (degrees) |
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c lon - longitude of grid point (radians) |
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c radius - radius of bottom of layer (m) |
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c darea - element of surface area (unit radius) |
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c dradius - element of radius (m) |
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c dvolume - element of volume (m**3) |
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c s - salinity at grid point (ppt) |
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c t - temperature at grid point (deg C) |
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c u - eastward velocity at grid point (m/s) |
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c v - northward velocity at grid point (m/s) |
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c density - density at grid point (kg/m**3) |
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c ae - earth s mean radius (m) (PREM value) |
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c grav - earth s mean gravity (m/s**2) (PREM) |
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c sbo_omega - earth s mean angular velocity (rad/s) |
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integer bi, bj, I, J, K |
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_RL lat, lat_deg, lon, radius, darea, dradius, dvolume, depth |
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_RL s, t, u, v, density |
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_RL ae /6.3710e6/ |
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_RL grav /9.8156/ |
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_RL sbo_omega /7.292115e-5/ |
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c initialize variables to be computed |
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xoamc = 0.0 |
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yoamc = 0.0 |
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zoamc = 0.0 |
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xoamp = 0.0 |
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yoamp = 0.0 |
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zoamp = 0.0 |
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mass = 0.0 |
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xcom = 0.0 |
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ycom = 0.0 |
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zcom = 0.0 |
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DO bj = myByLo(myThid), myByHi(myThid) |
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DO bi = myBxLo(myThid), myBxHi(myThid) |
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DO J = 1-OLy, sNy+OLy |
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DO I = 1-OLx, sNx+OLx |
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obp(I,J,bi,bj) = 0.0 |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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c loop over all grid points, accumulating mass, com, oam, and obp |
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do bj = myByLo(myThid), myByHi(myThid) |
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do bi = myBxLo(myThid), myBxHi(myThid) |
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do J = 1, sNy |
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do I = 1, sNx |
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|
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c latitude (rad) |
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lat_deg = yC(I,J,bi,bj) |
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lat = yC(I,J,bi,bj) * pi / 180.0 |
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c longitude (rad) |
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lon = xC(I,J,bi,bj) * pi / 180.0 |
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|
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c unit radius |
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darea = dyF(I,J,bi,bj) * dxF(I,J,bi,bj) / ae / ae |
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|
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do K = 0, Nr |
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c K=0 => ssh |
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if (K .eq. 0) then |
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|
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c if land, flag it in obp and skip it |
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if (_hFacC(i,j,1,bi,bj).eq.0.) then |
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obp(I,J,bi,bj) = -999.99 |
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goto 1010 |
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end if |
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|
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radius = ae |
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dradius = etaN(I,J,bi,bj) |
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c assume surface has same vel and density as first layer |
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s = salt(I,J,1,bi,bj) |
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t = theta(I,J,1,bi,bj) |
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u =(uvel(I,J,1,bi,bj)+uvel(I+1,J,1,bi,bj))/2. |
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v =(vvel(I,J,1,bi,bj)+vvel(I,J+1,1,bi,bj))/2. |
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|
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else |
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c if land, skip it |
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if (_hFacC(i,j,k,bi,bj).eq.0.) goto 1010 |
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c radius to center of cell (m) |
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radius = ae - abs(rC(K)) |
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dradius = drF(K) |
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s = salt(I,J,K,bi,bj) |
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t = theta(I,J,K,bi,bj) |
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u =(uvel(I,J,K,bi,bj)+uvel(I+1,J,K,bi,bj))/2. |
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v =(vvel(I,J,K,bi,bj)+vvel(I,J+1,K,bi,bj))/2. |
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end if |
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|
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c cell volume (m**3) |
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dvolume = darea * radius**2 * dradius |
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|
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c get density |
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depth = ae - radius |
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density = sbo_rho(depth,lat_deg,s,t) |
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c accumulate mass of oceans |
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mass = mass + density * dvolume |
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c accumulate center-of-mass of oceans |
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xcom = xcom + density * cos(lat) * cos(lon) |
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& * radius * dvolume |
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ycom = ycom + density * cos(lat) * sin(lon) |
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& * radius * dvolume |
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zcom = zcom + density * sin(lat) * |
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& radius * dvolume |
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|
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c accumulate oceanic angular momentum due to currents |
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xoamc = xoamc + ( v*sin(lon)-u*sin(lat)*cos(lon)) |
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& * density * radius * dvolume |
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yoamc = yoamc + (-v*cos(lon)-u*sin(lat)*sin(lon)) |
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& * density * radius * dvolume |
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zoamc = zoamc + u*cos(lat) |
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& * density * radius * dvolume |
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|
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c accumulate oceanic angular momentum due to pressure |
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xoamp = xoamp - sin(lat) * cos(lat) * cos(lon) |
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& * sbo_omega * density * radius**2 * dvolume |
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yoamp = yoamp - sin(lat) * cos(lat) * sin(lon) |
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& * sbo_omega * density * radius**2 * dvolume |
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zoamp = zoamp + cos(lat)**2 |
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& * sbo_omega * density * radius**2 * dvolume |
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|
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c accumulate ocean-bottom pressure |
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obp(I,J,bi,bj) = obp(I,J,bi,bj) + |
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& grav * density * dradius |
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|
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c end loop over depth |
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end do |
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|
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1010 continue |
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|
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c end loop over longitude |
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end do |
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|
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c end loop over latitude |
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end do |
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|
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c end loop over bi |
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end do |
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|
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c end loop over bj |
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end do |
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|
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c sum all values across model tiles |
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_GLOBAL_SUM_R8( mass , myThid ) |
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_GLOBAL_SUM_R8( xcom , myThid ) |
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_GLOBAL_SUM_R8( ycom , myThid ) |
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_GLOBAL_SUM_R8( zcom , myThid ) |
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_GLOBAL_SUM_R8( xoamc , myThid ) |
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_GLOBAL_SUM_R8( yoamc , myThid ) |
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_GLOBAL_SUM_R8( zoamc , myThid ) |
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_GLOBAL_SUM_R8( xoamp , myThid ) |
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_GLOBAL_SUM_R8( yoamp , myThid ) |
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_GLOBAL_SUM_R8( zoamp , myThid ) |
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|
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c finish calculating center-of-mass of oceans |
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xcom = xcom / mass |
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ycom = ycom / mass |
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zcom = zcom / mass |
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|
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#endif /* ALLOW_SBO */ |
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|
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return |
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end |
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