writenetcdf.h

Basilisk programme to write outputs as netcdf files. Written by Cyprien Bosserelle cyprien.bosserelle@niwa.co.nz 2018-2019 Usage: //Save this file in $BASILISK. In the modelling programme include this file with other includes at the top of the file: #include “writenetcdf.h” // First create a netcdf file - define name char ncfile[]=“TPacGebco-out.nc”; // In an initialisation event create file printf(“Create netcdf file for output ”); //Prepare netcdf file for output int nx=(int) 1 << MAXLEVEL; scalar * outvars = {eta,h,hmax,l,u.x,u.y}; create2dnc(ncfile,nx, L0, 0.0, outvars); // Output at designated timesteps (i.e. in ongoing event) printf(“Saving step: t=%f”,t); int nx=1<<MAXLEVEL; scalar * outvars = {eta,h,hmax,l,u.x,u.y}; write2varnc(ncfile,nx, t, outvars);

Still to do (useful but works without): Set attributes for _FillValue, missing_value

#include <netcdf.h>

double BiInterp(double q11, double q12, double q21, double q22, double x1, double x2, double y1, double y2, double x, double y)
{
    double x2x1, y2y1, x2x, y2y, yy1, xx1;
    x2x1 = x2 - x1;
    y2y1 = y2 - y1;
    x2x = x2 - x;
    y2y = y2 - y;
    yy1 = y - y1;
    xx1 = x - x1;
    return 1.0 / (x2x1 * y2y1) * (
        q11 * x2x * y2y +
        q21 * xx1 * y2y +
        q12 * x2x * yy1 +
        q22 * xx1 * yy1
    );
}


void create2dnc(char * ncfilename,int n, double len, double totaltime, scalar * outvars)
{
	int status;
	int ncid, xx_dim, yy_dim, time_dim, p_dim;

	int * tvar_id;

	int nvars = list_len(outvars);

	tvar_id=(int*)malloc(nvars*sizeof(int));


	double *xx,*yy, *var;

	double dx=len/n;

	xx = (double *)malloc(n*sizeof(double));
	yy = (double *)malloc(n*sizeof(double));
	var = (double *)malloc(n*n*sizeof(double));

	for (int ix=0; ix<n; ix++)
	{
		xx[ix]=ix*dx+ X0 + dx/2.;
		yy[ix]=ix*dx+ Y0 + dx/2.;
	}

	size_t nxx, nyy, ntt;
	size_t start[] = { 0, 0, 0 }; // start at first value
	size_t count[] = { 1, 1, 1 };
	count[1]=n;
	count[2]=n;


	int time_id, xx_id, yy_id, tt_id;	//
	nxx = n;
	nyy = n;


	//create the netcdf dataset
	status = nc_create(ncfilename, NC_NOCLOBBER, &ncid);

	//Define dimensions: Name and length

	status = nc_def_dim(ncid, "xx", nxx, &xx_dim);
	status = nc_def_dim(ncid, "yy", nyy, &yy_dim);

	status = nc_def_dim(ncid, "time", NC_UNLIMITED, &time_dim);
	int tdim[] = { time_dim };
	int xdim[] = { xx_dim };
	int ydim[] = { yy_dim };


	//define variables: Name, Type,...
	int  var_dimids[3];
	var_dimids[0] = time_dim;

	var_dimids[1] = yy_dim;
	var_dimids[2] = xx_dim;


	status = nc_def_var(ncid, "time", NC_DOUBLE, 1, tdim, &time_id);
	status = nc_def_var(ncid, "xx", NC_DOUBLE, 1, xdim, &xx_id);
	status = nc_def_var(ncid, "yy", NC_DOUBLE, 1, ydim, &yy_id);

	int kk=0;
	for (scalar s in outvars)
	{
		status = nc_def_var(ncid, s.name, NC_DOUBLE, 3, var_dimids, &tvar_id[kk++]);
	}



	status = nc_enddef(ncid);


	size_t tst[] = { 0 };
	size_t xstart[] = { 0 }; // start at first value
	size_t xcount[] = { 1 };
	xcount[0]=n;

	size_t ystart[] = { 0 }; // start at first value
	size_t ycount[] = { 1 };
	ycount[0]=n;





	//Provide values for variables
	status = nc_put_var1_double(ncid, time_id, tst, &totaltime);
	status = nc_put_vara_double(ncid, xx_id, xstart, xcount, xx);
	status = nc_put_vara_double(ncid, yy_id, ystart, ycount, yy);
	kk=0;
	for (scalar s in outvars)
	{
		for (int ii=0; ii<nxx; ii++)
		{
			for (int jj=0;jj<nyy;jj++)
			{
				var[ii+jj*nxx]=interpolate(s,ii*dx+ X0 + dx/2.,jj*dx+Y0+dx/2.);
			}

		}

		status = nc_put_vara_double(ncid, tvar_id[kk++], start, count, var);
	}
	status = nc_close(ncid);

	free(xx);
	free(yy);
	free(var);

}


void write2varnc(char * ncfilename,int n, double totaltime, scalar * outvars)
{
	int status;
	int ncid, time_dim, recid;
	size_t nxx, nyy;
	size_t start[] = { 0, 0, 0 }; // start at first value should be static?
	size_t count[] = { 1, n, n };

	// Is this absurd?
	count[1]=n;
	count[2]=n;

	static size_t tst[] = { 0 };
	int time_id, *var_id;

	int nvars = list_len(outvars);

	double * var;

	var_id=(int*)malloc(nvars*sizeof(int));

	var = (double *)malloc(n*n*sizeof(double));


	nxx = n;
	nyy = n;

	double dx= L0/n;

	static size_t nrec;
	status = nc_open(ncfilename, NC_WRITE, &ncid);

	//read id from time dimension
	status = nc_inq_unlimdim(ncid, &recid);
	status = nc_inq_dimlen(ncid, recid, &nrec);// What is the point of static definition if it is redefined here!
	//printf("nrec=%d\n",nrec);

	//read file for variable ids
	status = nc_inq_varid(ncid, "time", &time_id);
	int kk=0;
	for (scalar s in outvars)
	{
		status = nc_inq_varid(ncid, s.name, &var_id[kk++]);
	}

	start[0] = nrec;//
	tst[0] = nrec;

	//Provide values for variables
	status = nc_put_var1_double(ncid, time_id, tst, &totaltime);
	//status = nc_put_vara_double(ncid, var_id, start, count, var);
	kk=0;
	for (scalar s in outvars)
	{
		for (int ii=0; ii<nxx; ii++)
		{
			for (int jj=0;jj<nyy;jj++)
			{
				var[ii+jj*nxx]=interpolate(s,ii*dx+ X0 + dx/2.,jj*dx+Y0+dx/2.);
			}

		}

		status = nc_put_vara_double(ncid, var_id[kk++], start, count, var);
	}

	status = nc_close(ncid);

free(var);

}