void create_grid_from_text_file( char *file, int *nlon, int *nlat, double *x, double *y, double *dx, double *dy,
double *area, double *angle_dx )
{
double *xb, *yb;
int nx, ny, nxp, nyp, i, j, n;
FILE *pFile;
char mesg[256], txt[128];
nx = *nlon;
ny = *nlat;
nxp = nx + 1;
nyp = ny + 1;
pFile = fopen (file,"r");
if(!pFile) {
strcpy(mesg, "create_grid_from_file: Can not open ascii file ");
strcat(mesg,file);
mpp_error(mesg);
}
fscanf(pFile, "%s%*[^\n]",txt); /* header line (ignored) */
xb = (double *) malloc(nxp*sizeof(double));
yb = (double *) malloc(nyp*sizeof(double));
for(i=0;i<nxp;i++)
fscanf(pFile, "%lg", xb+i); /* longitude */
fscanf(pFile, "%s%*[^\n]",txt); /* header line (ignored) */
for(j=0;j<nyp;j++) fscanf(pFile, "%lg", yb+j); /* latitude */
fclose(pFile);
n=0;
for(j=0; j<nyp; j++) {
for(i=0; i<nxp; i++) {
x[n] = xb[i];
y[n] = yb[j];
angle_dx[n++] = 0;
}
}
/* zonal length */
n = 0;
for(j=0; j<nyp; j++) {
for(i=0; i<nx; i++ ) {
dx[n++] = spherical_dist(x[j*nxp+i], y[j*nxp+i], x[j*nxp+i+1], y[j*nxp+i+1] );
}
}
/* meridinal length */
n = 0;
for(j=0; j<ny; j++) {
for(i=0; i<nxp; i++ ) {
dy[n++] = spherical_dist(x[j*nxp+i], y[j*nxp+i], x[(j+1)*nxp+i], y[(j+1)*nxp+i] );
}
}
/* cell area */
n = 0;
for(j=0; j<ny; j++) {
for(i=0; i<nx; i++ ) {
area[n++] = box_area(x[j*nxp+i]*D2R, y[j*nxp+i]*D2R, x[(j+1)*nxp+i+1]*D2R, y[(j+1)*nxp+i+1]*D2R );
}
}
free(xb);
free(yb);
}; /* create_grid_from_text_file */
/***********************************************************************
void create_grid_from_file( char *file, int *nlon, int *nlat, double *x, double *y, double *dx,
double *dy, double *area, double *angle_dx )
the grid location is defined through ascii file. calculate cell length,
cell area and rotation angle
************************************************************************/
void create_grid_from_file( char *file, int *nlon, int *nlat, double *x, double *y, double *dx, double *dy,
double *area, double *angle_dx )
{
double *xb, *yb, *xt, *yt, *xc, *yc;
double p1[4], p2[4];
int nx, ny, nxp, nyp, ni, nj, i, j, n;
FILE *pFile;
char mesg[256], txt[128];
/************************************************************
identify the grid_file is ascii file or netcdf file,
if the file name contains ".nc", it is a netcdf file,
otherwise it is ascii file.
*********************************************************/
nx = *nlon;
ny = *nlat;
nxp = nx + 1;
nyp = ny + 1;
if(strstr(file, ".nc") ) {
int fid, vid;
ni = *nlon/2;
nj = *nlat/2;
xc = (double *)malloc((ni+1)*(nj+1)*sizeof(double));
yc = (double *)malloc((ni+1)*(nj+1)*sizeof(double));
xt = (double *)malloc( ni * nj *sizeof(double));
yt = (double *)malloc( ni * nj *sizeof(double));
fid = mpp_open(file, MPP_READ);
vid = mpp_get_varid(fid, "grid_lon");
mpp_get_var_value(fid, vid, xc);
vid = mpp_get_varid(fid, "grid_lat");
mpp_get_var_value(fid, vid, yc);
vid = mpp_get_varid(fid, "grid_lont");
mpp_get_var_value(fid, vid, xt);
vid = mpp_get_varid(fid, "grid_latt");
mpp_get_var_value(fid, vid, yt);
mpp_close(fid);
for(j=0; j<nj+1; j++) for(i=0; i<ni+1; i++) {
x[j*2*nxp+i*2] = xc[j*(ni+1)+i];
y[j*2*nxp+i*2] = yc[j*(ni+1)+i];
}
for(j=0; j<nj; j++) for(i=0; i<ni; i++) {
x[(j*2+1)*nxp+i*2+1] = xt[j*ni+i];
y[(j*2+1)*nxp+i*2+1] = yt[j*ni+i];
}
for(j=0; j<nj+1; j++) for(i=0; i<ni; i++) {
x[j*2*nxp+i*2+1] = (xc[j*(ni+1)+i]+xc[j*(ni+1)+i+1])*0.5;
y[j*2*nxp+i*2+1] = (yc[j*(ni+1)+i]+yc[j*(ni+1)+i+1])*0.5;
}
for(j=0; j<nj; j++) for(i=0; i<ni+1; i++) {
x[(j*2+1)*nxp+i*2] = (xc[j*(ni+1)+i]+xc[(j+1)*(ni+1)+i])*0.5;
y[(j*2+1)*nxp+i*2] = (yc[j*(ni+1)+i]+yc[(j+1)*(ni+1)+i])*0.5;
}
for(j=0; j<nyp; j++) for(i=0; i<nx; i++) {
p1[0] = x[j*nxp+i]; p2[0] = x[j*nxp+i+1];
p1[1] = y[j*nxp+i]; p2[1] = y[j*nxp+i+1];
dx[j*nx+i] = great_circle_distance(p1, p2);
}
for(j=0; j<ny; j++) for(i=0; i<nxp; i++) {
p1[0] = x[j*nxp+i]; p2[0] = x[(j+1)*nxp+i];
p1[1] = y[j*nxp+i]; p2[1] = y[(j+1)*nxp+i];
dy[j*nxp+i] = great_circle_distance(p1, p2);
}
for(j=0; j<ny; j++) for(i=0; i<nx; i++) {
p1[0] = x[j*nxp+i]; p1[1] = x[j*nxp+i+1]; p1[2] = x[(j+1)*nxp+i+1]; p1[3] = x[(j+1)*nxp+i];
p2[0] = y[j*nxp+i]; p2[1] = y[j*nxp+i+1]; p2[2] = y[(j+1)*nxp+i+1]; p2[3] = y[(j+1)*nxp+i];
area[j*nx+i] = poly_area(p1, p2, 4);
}
/* currently set angle to 0 */
for(j=0; j<nyp; j++) for(i=0; i<nxp; i++) angle_dx[j*nxp+i] = 0;
free(xt);
free(yt);
free(xc);
free(yc);
}
else {
pFile = fopen (file,"r");
if(!pFile) {
strcpy(mesg, "RegularSphericalGrid: Can not open ascii file ");
strcat(mesg,file);
mpp_error(mesg);
}
fscanf(pFile, "%s%*[^\n]",txt); /* header line (ignored) */
xb = (double *) malloc(nxp*sizeof(double));
yb = (double *) malloc(nyp*sizeof(double));
for(i=0;i<nxp;i++)
fscanf(pFile, "%lg", xb+i); /* longitude */
fscanf(pFile, "%s%*[^\n]",txt); /* header line (ignored) */
for(j=0;j<nyp;j++) fscanf(pFile, "%lg", yb+j); /* latitude */
fclose(pFile);
n=0;
for(j=0; j<nyp; j++) {
for(i=0; i<nxp; i++) {
x[n] = xb[i];
y[n] = yb[j];
angle_dx[n++] = 0;
}
}
/* zonal length */
n = 0;
for(j=0; j<nyp; j++) {
for(i=0; i<nx; i++ ) {
dx[n++] = spherical_dist(x[j*nxp+i], y[j*nxp+i], x[j*nxp+i+1], y[j*nxp+i+1] );
}
}
/* meridinal length */
n = 0;
for(j=0; j<ny; j++) {
for(i=0; i<nxp; i++ ) {
dy[n++] = spherical_dist(x[j*nxp+i], y[j*nxp+i], x[(j+1)*nxp+i], y[(j+1)*nxp+i] );
}
}
/* cell area */
n = 0;
for(j=0; j<ny; j++) {
for(i=0; i<nx; i++ ) {
area[n++] = box_area(x[j*nxp+i]*D2R, y[j*nxp+i]*D2R, x[(j+1)*nxp+i+1]*D2R, y[(j+1)*nxp+i+1]*D2R );
}
}
free(xb);
free(yb);
}
}; /* create_grid_from_file */
