Group Longwave Radiation
Allie Jones, Catrin Mills, Andy VanLoocke, Kirstin Gleicher
Scheme DifferencesRRTM
RRTMg (control)-a simplified version of RRTMApproximates radiative transfer with fewer points
Like wider rectangles approximating an integral
CAM 3.0Fewer absorbing gasses and spectral bandsEmissivity and absorptivity updated every 12 hrs
Neglects dependence on T, WV, Ozone Explains lack of diurnal cycle
Not an issue when clouds are present-dominant impact calculated at every call of rad. phys
U-WindCAM
RRTMG
RRTM
V-WindRRTM CAM
RRTMG
W-WindRRTM CAM
RRTMG
TemperatureRRTM
RRTMG
CAM
Temperature Difference Fields
Relative HumidityRRTM
RRTMG
CAM
RH Difference Fields
Surface and TOA Longwave Radiation
Surface Heat Fluxes
TOA and Surface Shortwave Flux
Conclusions
Little difference in RRTM and RRTMG
CAM shows major differences in RH at top and bottom of atmosphere.Also shows major difference in TOA outgoing LW
radiation