Category	URL
_null	https://hfradar.ioos.us/radials-erddap/erddap/categorize/standard_name/_null/index.xhtml?page=1&itemsPerPage=1000
latitude	https://hfradar.ioos.us/radials-erddap/erddap/categorize/standard_name/latitude/index.xhtml?page=1&itemsPerPage=1000
longitude	https://hfradar.ioos.us/radials-erddap/erddap/categorize/standard_name/longitude/index.xhtml?page=1&itemsPerPage=1000
time	https://hfradar.ioos.us/radials-erddap/erddap/categorize/standard_name/time/index.xhtml?page=1&itemsPerPage=1000