Adding GEO KOMPSAT-2A AMI and Himwari-8/9 AHI

[w-k-jones]

As both AMI and AHI share heritage with ABI, and now have data hosted on AWS, I thought it would be useful to add these datasets to goes2go so they can be accessed in the same manner as ABI data. I have a set of functions duplicating data.py for GK2A working, and am looking into loading AHI binary files using satpy, which should resolve #55. I just wanted to check with @blaylockbk if this is within the scope of goes2go and that you're happy for me to open a PR when these changes are ready.

Todo list:

• [x] Add GK2A AMI download/reader functions
• [ ] Add Himawari-8/9 AHI download/reader functions using satpy
• [ ] Consolidate common download/read functions shared between GOES, GK2A and Himawari
• [ ] Add GK2A/Himawari classes in the same manner as the GOES class
• [ ] Add multi-channel L1b reader, conversion of sensor counts to reflectance/BT and creation of "pseudo-MCMIP" datasets from L1b to allow use of RGB accessors

[blaylockbk]

Yes! This is something I'm very happy to add. 😊 This could greatly expand the audience. (side note, are the meteosats available anywhere? I haven't checked. Would like mtg-i1 when it's available, too)

I don't have much time to dedicate to goes2go at the moment, but I will find time to review a PR.

I would request making any new features and dependencies optional, if possible.

Could you include in the Readme/docs something like "goes2go works with more than just GOES-R series data, it helps you get Himawari and GeoKompsat2a too!" with some examples.

[cmo84]

@w-k-jones See section 5.1 here in the GOES-R PUG (product user guide) if you need documention on what goes in the metadata fields while replicating some subset of them in the course of this pseudo-MCMIP production. I'm thinking you may need to add at least the x and y and some of the geolocation related fields to get the accessors working?

@blaylockbk The meteosat data is indeed available through the eumdac library and loadable via satpy. The current active satellites are Meteosat 10 (EO:EUM:DAT:MSG:HRSEVIRI) and Meteosat 9 (EO:EUM:DAT:MSG:HRSEVIRI-IODC). The only caveat is that these require an API key to be used, which is freely available when creating an account at https://eoportal.eumetsat.int/cas/