CAMS zip files compressed mode is not enabled

Datasets and Usage CAMS - Datasets and Usage
1

I have noticed that when downloading CAMS products, they are provided as ZIP files. I understand that this format offers advantages, especially when a user queries multiple NetCDF files simultaneously. However, it seems that no compression is enabled: for a single file, the size of the ZIP file is identical to that of the extracted NetCDF file.

This raises two questions:

  1. Why is compression not enabled for the ZIP files?

  2. Why isn’t internal zlib compression used within the NetCDF files themselves?

I suspect the answer might be related to the computational load on the servers, but it seems unfortunate that such large, uncompressed files are being queried.

2

Hi Cyril. I completely agree. Unfortunately it’s a little bit complicated because some files benefit hugely from compression while others don’t at all, and compressing needlessly wastes time and resources as you say. It’s on our to-do list to implement a better approach to compression and I’m hoping we’ll achieve that in the coming weeks.

Luke.

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