IMAP Lo: Metadata updates for background-subtracted ISN

[jtniehof]

Change Summary

Updates to metadata for the background-subtracted ISN Lo L3 products. This is just the "easy" stuff, there's a lot more metadata related that impacts the code more directly (see "additional to do").

Overview

• Renamed the key variable to isn_rate_bg_subtracted -- was isn_bg_rate_subtracted, implying it's a background with some other rate subtracted.
• isn_rate_bg_subtracted not surprisingly goes negative a lot. Because of how we've set VALIDMIN, that means these values will be replaced with fill in most analysis tools. If people are averaging over time, this will inflate the average rates. These negatives need to be included in any averaging. I've changed VALIDMIN and added a VAR_NOTE, but this needs another scientist eye on it. (Nathan?) EDIT: Nathan has given thumbs-up.
• Clarified names and labels to have statistical uncertainty and systemic error, consistent with the map products spreadsheet.
• Other updates to labels and names in accordance with the map products spreadsheet
• Removed metadata for bg_subtracted_stat_err, as that variable doesn't exist

Additional to do

This should be either pushed to this PR before merge, or done just after merging, but this is the rest of metadata-related changes.

We should remove geometric factor because these are rates, not intensities. (And thus geometric_factor_stat_uncert). We should also remove bg_rates, bg_rates_stat_uncert, bg_rates_sys_err, counts, ena_count_rate, ena_count_rate_stat_uncert as they are inputs from the L2. If we keep any of these, there are metadata updates to do. There may be an argument for calculating background subracted counts independent of the count rate, but that's a future enhancement -- we're not doing it in the ENA products.

Nothing of interest to scientists below this, mostly bookkeeping

Variables energy_label, longitude_label, and latitude_label do not exist. Because these are coming in from isn_rate_data, maybe we address this in the input handling. We're not going to have separate L2 ISN right now, so if we use the main L2 ENA input that might fix it?

Might this be the same for energy_delta_plus and energy_delta_minus? We also have a separate energy_stat_uncert which doesn't seem relevant. I haven't updated metadata for this, not sure where it's coming from.

longitude_delta and latitude_delta also do not exist, and the code does not appear to copy them in from isn_rate_data even if present in that data set.

Updated Files

• imap_l3_processing/cdf/config/imap_lo_l3_variable_attrs.yaml
  • All attribute/metadata changes
• imap_l3_processing/lo/lo_processor.py
  • updates to support new name of isn_rate_bg_subtracted and clarifying stat_unc and sys_err

Testing

None done