FEA: Support for cos zenith angle in the ERA5 HDF5 dataloader

[mnabian]

Modulus Pull Request

Description

Closes #527

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The CHANGELOG.md is up to date with these changes.
• An issue is linked to this pull request.

Dependencies

[mnabian]

/blossom-ci

[mnabian]

@dallasfoster @loliverhennigh here's a comparison between the outputs of the two routines for zenith angle (np.max(z, 0)-1/pi) for '1983-10-19 06:00:00'. They don't match exactly.

[mnabian]

Reverting this change brings the two much closer, but there is still a small discrepancy

[dallasfoster]

Reverting this change brings the two much closer, but there is still a small discrepancy

Reverting this change makes the following two methods: datapipes/climate/utils/zenith_angle::_days_from_2000 and modulus/utils/zenith_angle::_days_from_2000 consistent.

[dallasfoster]

After reviewing each cos_zenith_angle code I am fairly confident that, after reverting the aforementioned change, the two codes are sufficiently equivalent.

[mnabian]

/blossom-ci