LBLRTM v12.17 spectral spacing?

[Szuchiam05]

This is more of a question, rather than an issue. I am upgrading our VERY old AER/LNFL/LBLRTM package from v12.4 to v12.17. Back in the v12.4 days, we will use 0.1 cm-1 spectral spacing for our forward model calculations. Is it correct that LBLRTM v12.17 has the spectral spacing 0.001 cm-1 for optical depth and transmittance output?

Thanks,
Chia

[pernak18]

@mjiacono @matt-alvarado @jrmascio i don't think i'm in a position to answer this question. do you have an answer?

[mjiacono]

I may have missed something, but I’m not aware of any changes to LBLRTM within the v12.x series of updates that altered the scanning or interpolation capabilities beyond the documented functionality as indicated in the question. You should be able to request the listed DVOUT values for optical depth and transmittance output.

[Szuchiam05]

I see!!! Will go with your recommendation and output the DV. Thank you!!!

[Szuchiam05]

Question: IF i don't list the DVOUT, these are what I get from optical depth

K>> tmp_opd(1).dv

ans =

0.0112

K>> tmp_opd(100).dv

ans =

1.7900e-04

So, how does this 0.001 cm-1 spectral spacing comes from? IF I want a uniformed spectral spacing, I need to specify DVOUT in TAPE5 record 1.3, is that right?

[mjiacono]

There are a number of algorithmic factors that control the DV that the model uses internally for the calculation in each layer. You can specify the DV of the optical depth monochromatic output using DVOUT, but DVOUT has to be less than the default DV selected by the model.