Default download format for ncss grid requests

[haileyajohnson]

Currently the download formats for grid requests are hardcoded in the following order: NETCDF3, NETCDF4, NETCDF4EXT
The browser UI defaults to the first value, NETCDF3, however some users have requested it default to NETCDF4 for the potential compression.

Some possibilities include:

• do nothing, leave the default as the first value
• change the hardcoded order of the output formats
• make the order configurable on the user-end
• dynamically choose a default based on the dataset itself?

Current order is here

[edesfandiari]

We would like to suggest changing the default downloading method to 'netCDF4' (or at least make it configurable) as it generates data with smaller file size which may improve the downloading time and may save storage at the user end. Following example
helps demonstrate the difference (~11.5 MB .nc4 vs. ~20.5 MB .nc download):

https://goldsmr4.gesdisc.eosdis.nasa.gov/thredds/ncss/MERRA2_aggregation/M2T1NXAER.5.12.4/M2T1NXAER.5.12.4_Aggregation_2022.ncml?var=DUEXTTAU&var=OCANGSTR&var=OCEXTTAU&north=50.0000&west=-100.0000&east=10&south=-50.0000&horizStride=1&time_start=2022-01-01T00%3A30%3A00Z&time_end=2022-01-02T23%3A30%3A00Z&timeStride=1&addLatLon=true&accept=netcdf4

https://goldsmr4.gesdisc.eosdis.nasa.gov/thredds/ncss/MERRA2_aggregation/M2T1NXAER.5.12.4/M2T1NXAER.5.12.4_Aggregation_2022.ncml?var=DUEXTTAU&var=OCANGSTR&var=OCEXTTAU&north=50.0000&west=-100.0000&east=10&south=-50.0000&horizStride=1&time_start=2022-01-01T00%3A30%3A00Z&time_end=2022-01-02T23%3A30%3A00Z&timeStride=1&addLatLon=true&accept=netcdf

[sshencloud]

Hi, I am a THREDDS user, I would like to suggest changing the default downloading method to 'netCDF4' (or at least make it configurable when installing). The subset data file size in netCDF3 may be larger than the original file. Thanks!