EAMxx: Current SPA will increase AOD when interpolating from L80 to L128

Currently, SPA interpolates layer aerosol optical depth (AER_TAU_SW, AER_TAU_LW) from L80 in input files, derived from v3 LR runs, to L128 in EAMxx. Layer aerosol optical depth is an integration of aerosol extinction through the layer depth. The arithmetic sum of the layer aerosol optical depth is the AOD.

Interpolating layer AOD, which is an integral and depends on layer depth, between different vertical coordinate will cause issues. Many layers in L80 are thicker than the layer depth in L128. Interpolating the layer aerosol optical depth from L80 to L128 will result in larger AOD.

The global annual mean AOD at visible band (aer_tau_sw) in EAMxx (0.232) is much larger than AOD from SPA input files (0.118).