Details on the Specific Chosen g-values

[LeeJace]

Dear all,

While reviewing the RRTMG module components (located at cam/src/physics/rrtmg/aer_src/rrtmg_lw_k_g.F90), I noticed the description regarding the absorption coefficients, specifically:

The array KAO contains absorption coefficients at the 16 chosen g-values for a range of pressure levels above ~100mb and temperatures.

However, it does not specify the exact 16 g-values used.

I would appreciate any documentation available on the selection of these g-values and their effects (why such g-values and so on).

Thank you!

 

[peverley]

Hi, Lee.

It looks like the g-points are subdivisions of bands and don't have any physical meaning (just used for integration, etc). For more information, you can refer to this paper on RRTMG (Table 2 on page 7 might be what you're looking for):

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/97JD00237

Or, more recently, this one on RRTMGP:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019MS001621