GEODEMO_4b

Compare horizontal slices from two different CF compliant structured grid models (CH3D and ROMS) at a particular time step and depth, using geosubset to subset the data

Contents

CH3D

url{1}='http://testbedapps.sura.org/thredds/dodsC/estuarine_hypoxia/ch3d/agg.nc';
var{1}='salinity';
titl{1}='CH3D';

ROMS

url{2}='http://testbedapps.sura.org/thredds/dodsC/estuarine_hypoxia/chesroms_1tdo/agg.nc';
var{2}='salt';
titl{2}='CHESROMS';

Create geosubset object

dat=[2005 1 10 0 0 0];  % Jan 10, 2005 00:00 UTC
depth=-5;  % horizontal slice 5 m from surface
ax=[ -76.5220  -75.7105   36.8248   37.7850]; %lon/lat range
cax=[0 33];  %color range
lat_mid=38; % for scaling plots

s.time=dat;
s.lon=ax(1:2);
s.lat=ax(3:4);

Perform analysis without using dataset dependant code

Access datasets, subset data, interpolate data to a constant z, plot results at z depth

figure;
for i=1:length(url);
  nc{i}=ncgeodataset(url{i});
  % create a salinity geovariable object.  No data read yet.
  svar{i}=geovariable(nc{i},var{i});
  disp(['reading data from ' titl{i} '...'])
  % using geosubset here, which allows for subsetting and striding, reading
  % multiple time steps, only certain zlevels and more.
  sub{i}=svar{i}.geosubset(s);
  sz{i}=zsliceg(squeeze(sub{i}.data),squeeze(sub{i}.grid.z),depth);
  a{i}=subplot(1,length(url),i);
  pcolorjw(sub{i}.grid.lon,sub{i}.grid.lat,double(sz{i}));colorbar
  axis(ax);
  caxis(cax);
  title(sprintf('%s, depth=%f: %s',titl{i},depth,datestr(sub{1}.grid.time)));
  set (a{i}, 'DataAspectRatio', [1 cos(lat_mid*pi/180) 1000] );
end

reading data from CH3D...
reading data from CHESROMS...

Published with MATLAB® 7.13