SSUSI bug

[aburrell]

Description

Addresses an issue found when loading subsequent days of DMSP SSUSI SDR-Disk data, which caused a memory failure. Fixed by adding a custom concat_data method. This shares many lines of code with TIMED GUVI, so the comment elements were moved to pysatNASA.instruments.methods.jhuapl.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

import datetime as dt
import pysat

ssusi = pysat.Instrument('dmsp', 'ssusi', 'sdr-disk', 'f18')
stime = dt.datetime(2010, 4, 14)

ssusi.load(date=stime)  # Will be fine

stime += dt.timedelta(days=1)
ssusi.load(date=stime)  # Will fail and potentially crash your computer without fix

Test Configuration:

• Operating system: OS X Big Sur
• Version number: Python 3.9
• Any details about your local setup that are relevant: develop branch of pysat

Checklist:

• Make sure you are merging into the develop (not main) branch
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• Add a note to CHANGELOG.md, summarizing the changes
• Update zenodo.json file for new code contributors

If this is a release PR, replace the first item of the above checklist with the release
checklist on the wiki: https://github.com/pysat/pysat/wiki/Checklist-for-Release

[jklenzing]

Could you rebase into the #227 pull? That is the most functional branch and may fix the issues with test failure here