Using the HFRnet Thredds Data Server (TDS) to access HF radar derived surface current archive
This guide will provide an overview to using the HFRNet TDS to access surface currents from IOOS supported HF radar network.
- Pick your region. Regions include:
- USWC – US West Coast
- USEGC – US East and Gulf Coast
- USHI – US Hawaii
- PRVI – Puerto Rico and Virgin Islands
- AKNS – Alaska North Slope
- Pick your product. Products include
- Hourly Real Time Vector currents (RTV)
- 500m horizontal resolution (not available for all regions)
- 1km horizontal resolution
- 2km horizontal resolution
- 6km horizontal resolution
- Long Term Averages (LTA)
- Annual RTV average
- Monthly RTV average
- Choose “Best Time Series”
- At this point, you will see the dataset page and will see various methods for access including,
- OpenDap (previously DODS) provides programmatic interface to HFR archive. Use this if you are accessing the archive through python, Matlab, R and other programming languages that support the opendap protocol.
- NetcdfSubset provides an easy way to subset the data in geographical space and time. Use this if you want to download a netCDF file and use netCDF aware tools for analysis.
- OpenGIS Web Map Service. Use this with GIS and web mapping tools to provide a georeferenced layer of the archive data.
- OpenGIS Web Coverage Service.
- You can get a quick view of the archived data using Godiva2 listed under Viewers towards the bottom of the dataset page.
If you are carrying out extended analysis with tools such as python or Matlab, you should use this service. Click through the OPENDAP link of your selected dataset and copy the Data URL. Example scripts are available for python, Matlab and R at https://github.com/rowg/HFRnet-Thredds-support
If you want the data to be delivered in a netCDF file or you are using a programming language that doesn’t support OpenDap, use the NetCDFSubset service. Directions for use follows:
- Select Variables
- Variables include u & v components of surface current and DOPx and DOPy, which are errors due to the geometric dilation of the gridded data.
- If you want to subset the bounding box of your data request, click off the checkbox that says “Disable horizontal subsetting”.
- Input your latitude and longitude ranges
- Choose time range.
- Please note the server cannot support very large requests, and may not return adequate error messages with failed requests. If you are receiving bad data, please try your request again on a shorter time range.
- Click on box to “Add Lat/Lon variables”
- Keep format on netcdf as netcdf4 does not support subsetting (will be fixed in next version).
- Copy NCSS Request URL for your records.
- Click Submit button and save netcdf file