Ayush Nag

Results 2 issues of Ayush Nag

- [x] Closes #605 - [x] Fix scale_factor, add_offset bug - [x] Find precise permissions URL (not DAAC general) - [x] Add docs - [x] Unit tests. Update current test...

The idea is to speed up opening up netcdf4/hdf5 datasets with a NASA specific optimization. Load data like `xr.open_mfdataset` with kerchunk/zarr speeds by translating **existing dmr++ metadata files to zarr...