ows_papa.c

Ocean Weather Ship Papa test case from GOTM

Ocean Weather Ship Papa test case from GOTM

See the GOTM web site and section 12.3.1 of the GOTM manual.

“This scenario is a classical scenario for the Northern Pacific, for which long term observations of meteorological parameters and temperature profiles are available. The station Papa at 145^\circW, 50^\circN has the advantage that it is situated in a region where the horizontal advection of heat and salt is assumed to be small. Various authors used these data for validating turbulence closure schemes.”

Results

set term PNG size 800,400
set output 'Tobs.png'
set pm3d map
# jet colormap
set palette defined ( 0 0 0 0.5647, 0.125 0 0.05882 1, 0.25 \
 0 0.5647 1, 0.375 0.05882 1 0.9333, 0.5 0.5647 1 0.4392,   \
 0.625 1 0.9333 0, 0.75 1 0.4392 0, 0.875 0.9333 0 0,       \
 1 0.498 0 0 )
set cbrange [4:17]
set yrange [-250:0]
unset xlabel
unset key
set ylabel 'z (m)'
set xdata time
set timefmt "%Y/%m/%d"
set xrange ["1961/03/25" : "1962/03/25"]
set xtics rotate by 45
set xtics center offset 0,-0.5
set timefmt "%Y/%m/%d %H:%M:%S"
splot "< awk '{ if (NF == 4) { time = $1 \" \" $2; print \"\"; } \
                else if (NF == 2) print time, $0;}' tprof.dat" u 1:3:4

Evolution of the potential temperature (field data) (script)

set output 'T.png'
set timefmt "%s"
start = system("date -d'1961-03-25' +%s")
splot '../ows_papa/out' u (start + $1):2:5

$Evolution of the potential temperature (k-\epsilon model) (script)$

Evolution of the potential temperature (k-\epsilon model) (script)

Something strange seems to happen for KPP around 01/01/1962.

set output 'Tkpp.png'
splot '../ows_papa-kpp/out' u (start + $1):2:5

Evolution of the potential temperature (KPP model) (script)

References

[gotm]

Lars Umlauf, Hans Burchard, and Karsten Bolding. GOTM Source Code and Test Case Documentation, version 4 edition, 2018. [ .pdf ]

#include "grid/multigrid.h"
#include "layered/hydro.h"
#include "layered/gotm.h"

We add temperature and salinity fields for each layer.

event defaults (i = 0)
{
  T = new scalar[nl];
  S = new scalar[nl];
}

event cleanup (i = end) {
  delete ({T, S});
}

This case depends on (0D) Coriolis terms.

#define F0() (2.*(2.*pi/86164.)*sin(2.*pi*y/360.))

event coriolis (i++)
{
  foreach() {
    double cosomega = cos (F0()*dt);
    double sinomega = sin (F0()*dt);
    foreach_layer() {
      double ua = u.x[];
      u.x[] =   ua*cosomega + u.y[]*sinomega;
      u.y[] = - ua*sinomega + u.y[]*cosomega;
    }
  }
}

The external GOTM global variables a, g1 and g2 control the Jerlov-type extinction of the short-wave radiation flux.

#include <gotm/observations/observations.h> // for a, g1, g2

The starting date.

int syear = 1961, smonth = 3, sday = 25;

int main()
{
  foreach_dimension()
    periodic (right);
  size (100e3);
  origin (- 145. - L0/2., 50. - L0/2.);
  G = 9.81;
  N = 1;
  nl = 250;
  CFL = CFL_H = HUGE;

These are set to match those used in the GOTM reference case.

  observations_a = 0.58, observations_g1 = 0.35, observations_g2 = 23.;
    
  //  eqstate_eq_state_mode = 1; // does not work with kpp

The GOTM turbulence model setup

Two versions can be used KPP or k-\epsilon. The number of parameters for k-\epsilon seems way too large…

  meanflow_maxitz0b = 1;	// default = 10

#if KPP // kpp
  turbulence_turb_method = 99;	// default = 0
  kpp_kpp_sbl = true;	        // default = 0
  kpp_kpp_bbl = true;	        // default = 0
  kpp_kpp_interior = true;      // default = 0
  kpp_ric = 0.3;      	        // default = 0
#else // k-epsilon
  turbulence_iw_model = 2;	// default = 0 // no effect whatsoever!!
  
  turbulence_turb_method = 3;	// default = 2
  turbulence_compute_c3 = 1;	// default = 0
  turbulence_length_lim = 1;	// default = 0
  turbulence_const_num = 0.0001;	// default = 0.0005
  turbulence_const_nuh = 0.0001;	// default = 0.0005
  turbulence_k_min = 1e-06;	// default = 1e-08
  turbulence_kb_min = 1e-10;	// default = 1e-08
  turbulence_epsb_min = 1e-14;	// default = 1e-12
  turbulence_gen_m = 1;	// default = 1.5
  turbulence_gen_n = -0.67;	// default = -1
  turbulence_cpsi1 = 1;	// default = 1.44
  turbulence_cpsi2 = 1.22;	// default = 1.92
  turbulence_cpsi3minus = 0.05;	// default = 0
  turbulence_sig_kpsi = 0.8;	// default = 1
  turbulence_sig_psi = 1.07;	// default = 1.3
  turbulence_ce3minus = -0.4;	// default = 0
  turbulence_my_length = 3;	// default = 1

  turbulence_scnd_method = 1;	// default = 0
  turbulence_kb_method = 1;	// default = 0
  turbulence_epsb_method = 1;	// default = 0
  turbulence_scnd_coeff = 7;	// default = 0
  turbulence_cc1 = 3.6;	// default = 0
  turbulence_cc2 = 0.8;	// default = 0
  turbulence_cc3 = 1.2;	// default = 0
  turbulence_cc4 = 1.2;	// default = 0
  turbulence_cc6 = 0.3;	// default = 0
  turbulence_ct1 = 3.28;	// default = 0
  turbulence_ct2 = 0.4;	// default = 0
  turbulence_ct3 = 0.4;	// default = 0
  turbulence_ct5 = 0.4;	// default = 0
  turbulence_ctt = 0.8;	// default = 0
  turbulence_alpha = 0.7;	// default = 0
  turbulence_nuhiw = 1e-05;	// default = 5e-05
#endif

Forcing flux data

These were derived from observations.

  #define GOTM_CASES "https://github.com/gotm-model/cases/raw/master/"

  system ("test -f sst.dat || ( "
	  "wget -q " GOTM_CASES "ows_papa/heatflux.dat && "
	  "wget -q " GOTM_CASES "ows_papa/momentumflux.dat && "
	  "wget -q " GOTM_CASES "ows_papa/sprof.dat && "
	  "wget -q " GOTM_CASES "ows_papa/sst.dat && "
	  "wget -q " GOTM_CASES "ows_papa/swr.dat && "
	  "wget -q " GOTM_CASES "ows_papa/tprof.dat "
	  ")");
  
  run();
}

Initial conditions

A rough function to read GOTM-formatted data files.

void init_profile (Point point, const char * fname,
		   int sy, int sm, int sd, scalar s)
{
  FILE * fp = fopen (fname, "r");
  if (!fp) {
    perror (fname);
    exit (1);
  }
  int yy, m, d, n;
  do {
    if (fscanf (fp, "%d/%d/%d %*s %d %*d", &yy, &m, &d, &n) != 4) {
      fprintf (stderr, "%s: error: cannot read date\n", fname);
      exit (1);
    }
    if (yy < sy || (yy == sy && m < sm) || (yy == sy && m == sm && d < sd))
      for (int i = 0; i < n; i++)
	fscanf (fp, "%*f %*f");
    else
      break;
  } while (1);
  double zd[n], od[n];
  int i = 0;
  while (fscanf (fp, "%lf %lf", &zd[i], &od[i]) == 2)
    i++;
  if (i != n) {
    fprintf (stderr, "%s: error: not enough points: read %d out of %d\n",
	     fname, i, n);
    exit (1);
  }
  double zc = zb[];
  foreach_layer() {
    zc += h[]/2.;
    int i;
    for (i = 1; i < n && zd[i] >= zc; i++);
    if (i < n)
      s[] = (od[i-1]*(zd[i] - zc) + od[i]*(zc - zd[i-1]))/(zd[i] - zd[i-1]);
    else
      s[] = od[i-1];
    zc += h[]/2.;
  }
  fclose (fp);
}

The initial temperature and salinity profiles are obtained from the data.

event init (i = 0)
{
  if (turbulence_turb_method != 99)
    turbulence_report_model();
  foreach() {
    zb[] = - 250.;
    foreach_layer()
      h[] = 250./nl;
    init_profile (point, "sprof.dat", syear, smonth, sday, S);
    init_profile (point, "tprof.dat", syear, smonth, sday, T);
  }
}

Timestep

Set to one hour, as in the GOTM test case.

event timestep (t += 3600);

Surface fluxes

Momentum

vector tau[];

event input_momentum_flux (i += 3)
{
  static FILE * fp = fopen ("momentumflux.dat", "r");
  static coord hfp, hfn;    
  // the file is sampled at 3 hours intervals
  if (i == 0) {
    int y, m, d;
    while (fscanf (fp, "%d/%d/%d %*s %lf %lf", &y, &m, &d, &hfn.x, &hfn.y) == 5
	   && (y < syear || m < smonth || d < sday));
  }
  if (i % 3 == 0) {
    hfp = hfn;
    fscanf (fp, "%*s %*s %lf %lf", &hfn.x, &hfn.y);
  }
  coord hf;
  foreach_dimension()
    hf.x = hfp.x + (i % 3)/3.*(hfn.x - hfp.x);
  foreach()
    foreach_dimension()
      tau.x[] = hf.x;
  airsea_tau = tau;
}

Heat

scalar heat_flux[];

event input_heat_flux (i += 1)
{
  static FILE * fp = fopen ("heatflux.dat", "r");
  static double hfp, hfn;    
  // the file is sampled at 3 hours intervals
  if (i == 0) {
    int y, m, d;
    while (fscanf (fp, "%d/%d/%d %*s %lf", &y, &m, &d, &hfn) == 4 &&
	   (y < syear || m < smonth || d < sday));
  }
  if (i % 3 == 0) {
    hfp = hfn;
    fscanf (fp, "%*s %*s %lf", &hfn);
  }
  double hf = hfp + (i % 3)/3.*(hfn - hfp);
  foreach()
    heat_flux[] = hf;
  airsea_heat_flux = heat_flux;
}

Short-wave radiation

We keep the option to compute these from solar zenith angle etc… but it is not used by default.

#include <gotm/airsea/solar_zenith_angle.h>
#include <gotm/airsea/albedo_water.h>
#include <gotm/util/time.h>

scalar swr_flux[];

event input_swr_flux (i += 1)
{
  static FILE * fp = fopen ("swr.dat", "r");
  static double hfp, hfn;    
  // the file is sampled at 3 hours intervals
  if (i == 0) {
    int y, m, d;
    while (fscanf (fp, "%d/%d/%d %*s %lf", &y, &m, &d, &hfn) == 4 &&
	   (y < syear || m < smonth || d < sday));
  }
  if (i % 3 == 0) {
    hfp = hfn;
    fscanf (fp, "%*s %*s %lf", &hfn);
  }
  double hf = hfp + (i % 3)/3.*(hfn - hfp);

#if 0  
  int julianday, year = 1959, month = 9, day = 14;
  time_julian_day (&year, &month, &day, &julianday);
  julianday += t/86400.;
  // fixme: assumes t start at midnight
  double secondsofday = fmod (t, 86400.);
  double hoursofday = secondsofday/3600.;
  
  int firstjan;
  month = 1, day = 1;
  time_julian_day (&year, &month, &day, &firstjan);
  int yearday = julianday - firstjan + 1;
#endif
  
  foreach() {
#if 0    
    realtype zenith_angle =
      airsea_solar_zenith_angle (&yearday, &hoursofday, &x, &y);
    realtype albedo = airsea_albedo_payne (&zenith_angle);
#endif
    swr_flux[] = hf; // *(1. - albedo);
  }
  airsea_swr_flux = swr_flux;
}

Outputs

void profile (FILE * fp)
{
  foreach() {
    double z = zb[];
    foreach_layer()
      fprintf (fp, "%g %g %g %g %g %g %g %g\n", t, z + h[]/2.,
	       u.x[], u.y[], T[], S[],
	       meanflow_nn.a[point.l + 1], turbulence_nuh.a[point.l + 1]),
      z += h[];
  }
  fprintf (fp, "\n");  
}

event profiles (i += 12)
  profile (stdout);

event end (i = 365*24)
  profile (stderr);