How to use the OPeNDAP / DODS Server in MATLAB.

The following explains the steps of loading data servered by OPeNDAP using MATLAB.

Select a dataset on a OPeNDAP server:

• Earth Simulator Center (authentication required)
• IPRC only (authentication required)
• Public data

Get the URL by clicking on "info" for the dataset of your interest, say NLOM on the "Public data" server, which looks like this:

OPeNDAP Server (GDS) - top level - public_data - NLOM_32


OPeNDAP Server (GDS) - directory for /public_data/NLOM_32 : 4 entries

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1: nlom_ssh_32: NLOM 1/32deg SSH   info  dds  das

The OPeNDAP URL is near the top of the "info" page and looks like:

DODS URL:	http://apdrc.soest.hawaii.edu/dods/public_data/NLOM_32/nlom_ssh_32
Authenticated:	http://username:passwd@apdrc.soest.hawaii.edu/dods/public_data/NLOM_32/nlom_ssh_32

Download and install the MATLAB OPeNDAP Command Line tool (or Structs tool) client:

http://www.opendap.org/download

Load data using loaddods / loaddap (loaddap replaces loaddods on newer installations) and proceed as you normally would:

x=loaddods( 'http://apdrc.soest.hawaii.edu/dods/public_data/NLOM_32/nlom_ssh_32?ssh[523:523][0:0][2880:3072][3618:3891]');
Loads the NRL NLOM sea surface height for Oct 3, 2006, 165W-153W, 18N-24N. Note indices start from 0.

help loaddods
Information on how to use loaddods

m=find(x<-1.0e33); x(m)=ones(size(m))+NaN;
Fill missing data with NaN

lat=18:1/32:24;
lon=36:360/8192:395.9122; lon=lon(3618:3891)-360;
contourf(lon,lat',x)
colorbar
Contour sea surface height

Instructions for IPRC "Theme" linux computers

addpath /usr/local/share/loaddap
addpath /usr/local/bin
After starting Matlab (or add to Matlab startup), directories need to be added to the search path.

whodap('http://apdrc.soest.hawaii.edu:80/dods/public_data/NLOM_32/nlom_sst_32')
Returns grid information of dataset

x=loaddap('http://apdrc.soest.hawaii.edu:80/dods/public_data/NLOM_32/nlom_sst_32?sst[852:852][0:0][2829:3554][3500:5000]')
Puts the requested subset of data into structure x.

sst=x.sst.sst;
m=find(sst<-1.0e33); sst(m)=ones(size(m))+NaN;
contourf(x.sst.lon,x.sst.lat',sst)
Contour sea surface temperature

For more information visit the MATLAB/DODS handbook