get_hycom_online

A MATLAB function to download hycom data easily (1992-10-02 to present)

New features (9 Mar, 2025)

1. get_hycom_online works for the latest hycom product after 2024-09-04 (ESPC-D-V02).
2. the downloaded file can be saved in NetCDF format.
3. the prefix name of downloaded files can be customized.
4. the provided region can cross the longitudinal boundaries of hycom products.

Example-1: Download HYCOM data of a particular moment

clc;clearvars
aimpath = 'E:\data\';
region = [190 240 -5 5]; % Niño 3.4
% region = [160 210 -5 5]; % Niño 4 
timeTick = datetime(2010,1,1);
varList = {'ssh','temp','salt','uvel','vvel'};    
D = get_hycom_online(aimpath, region, timeTick, varList);

Example-2: Download HYCOM data in netcdf format and customize prefix names

clc;clearvars
aimpath = 'E:\data\';
region = [117.5 122.5 37 41]; % the Bohai Sea
timeTick = datetime(2010,1,1);
varList = {'ssh','temp','salt','uvel','vvel'};
D = get_hycom_online(aimpath, region, timeTick, varList, 'format', 'netcdf', 'prefix', 'bohai_sea');

Example-3: Download HYCOM data in batch

clc;clearvars
aimpath = 'E:\data\';
region = [117.5 122.5 37 41]; % the Bohai Sea
timeList = datetime(2020,1,1):hours(3):datetime(2020,2,1);
varList = {'ssh','temp','salt','uvel','vvel'};

nTimes = numel(timeList);
for iTime = 1:nTimes
    timeTick = timeList(iTime);
    D = get_hycom_online(aimpath, region, timeTick, varList);
end

Example-4: Download data from a specified HYCOM product

clc;clearvars
aimpath = 'E:\data\';
region = [261 280 17.5 32.5]; % the Gulf of Mexico
timeTick = datetime(2010,1,1);
varList = {'ssh','temp','salt','uvel','vvel'};    
URL = 'http://tds.hycom.org/thredds/dodsC/GLBy0.08/expt_93.0?';
D = get_hycom_online(aimpath, region, timeTick, varList, 'URL', URL);

Notes

Niño 4 region is a good example because it crosses the longitudinal boundaries ([-180,180]) of some hycom products. In this case, the function will splice the west and east parts together to get the desired data.

Tidal signals are included in the latest HYCOM product (ESPC-D-V02), as illustrated in the figure below, whereas they were absent in earlier versions.