Extensions to the SSM

[AndrewILWilliams]

Building on #379 , there are a few extensions to the SSM framework which we might consider. Listed in order of importance (to me):

• Implement a simple spectral representation of the H2O continuum and its temperature-dependence (we currently don't include temperature-scalings, so would need to brainstorm a way to do this)
• Add simplified spectral representation of ozone for the shortwave (should be very easy, just need to update this line)
• Add simple representation of Rayleigh scattering (how does RRTMGP do this at the moment?)

[RobertPincus]

Ooh, and I'd like to

• Make the SSM compatible with OpenACC/OpenMP for GPUs

[RobertPincus]

Working on the OpenACC SSM with #383

[RobertPincus]

Ooh, and I'd like to

• Make the SSM compatible with OpenACC/OpenMP for GPUs

Done with #383 (though we haven't checked the answers or the data movement)

[RobertPincus]

Treating the water vapor continuum might also mean including a quadratic dependence of the self-continuum on concentration.