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ssec / polar2grid

Tools for reading, remapping, and writing satellite instrument data.
http://www.ssec.wisc.edu/software/polar2grid/
GNU General Public License v3.0
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Default daytime band products should be reflectances #707

Open kathys opened 2 weeks ago

kathys commented 2 weeks ago

Our boss Liam has requested that Polar2Grid create actual reflectances that include division by the cosine of the solar zenith angle for each of the polar orbiting satellites that we support, including AVHRR and MODIS. This should be the default daytime reflectance band output.

djhoese commented 2 weeks ago

What about geo2grid readers?

kathys commented 2 weeks ago

I will speak to Graeme about the defaults for G2G.

djhoese commented 2 weeks ago

My plan for implementing this would be to make "aliases" for all channels requested from the command line that are visible channels. In Satpy terms, they would be an alias for DataQuery(name="<channel name>", modifiers=("sunz_corrected",)). This should mean that any existing composites will not be affected.

In normal software versioning terms, I'm tempted to say this is almost a "major" change deserving of a 4.0 release but I suppose it doesn't have to be. Just something that popped in my head when thinking about this last night.

kathys commented 2 weeks ago

I understand why you would say this. I think it will also add processing time too. But I think it is the right thing to do, and Liam is right in that our users, especially in the polar regions, will get uniform images across sensors. An important part of this change will be to make sure that I document it well for end users.

djhoese commented 2 weeks ago

Any idea if there are any readers (AVHRR?) where we don't have access to solar zenith angles and they would have to be computed on-the-fly from the lon/lats? That would take the processing time hit from insignificant to extremely annoying.