Problems in downloading netcdf4 zip files using opendap

[jinqj]

Hello, I used the following wget command to download TROPOMI Aerosol Index data successfully several month ago:

wget https://tropomi.gesdisc.eosdis.nasa.gov/opendap/hyrax/S5P_TROPOMI_Level2/S5P_L2__AER_AI_HiR.2/2025/001/S5P_OFFL_L2__AER_AI_20241231T235600_20250101T013730_37407_03_020800_20250102T180053.nc.nc4?PRODUCT_time_utc,PRODUCT_latitude,PRODUCT_longitude

The downloaded files are netcdf4 in classic zip format. However, I used the same command yesterday and the downloaded files are netcdf4 format without any compression, so the file size increased by about 50%. I want to ask if anybody knows why this difference happens and how I can use a similar command to download the compressed netcdf4 files to save storage space.

Thanks in advance,
Qinjian Jin

[GES DISC - emilyz]

The compression for on-prem Tropomi Hyrax server was recently switched off
to avoid server timeouts and errors when downloading variables with large
dynamic size floating-point arrays. We are preparing to port this collection
to our cloud OPeNDAP soon. Once there, compression will be enabled since
timeouts should no longer be an issue.

[jinqj]

Thanks a lot for your clarification. Hope to explore the on-cloud TROPOMI data in the future.

Best regards,
Qinjian