This page evaluates CKD models generated by the "PSLACKD" tool. Note that these models are only intended for use with present-day greenhouse-gas concentrations, so have not been evaluated in alternative climate scenarios.


PSLACKD version 5.002 uses 14 bands in the longwave and the model evaluated has a total of 79 g-points.  The performance of broadband heating rates and fluxes in present-day conditions is as follows, evaluated using line-by-line calculations on the 50 CKDMIP "Evaluation-1" profiles:

The evaluation in each of the 14 bands is shown here (in order of decreasing wavenumber):

or equivalently plotted in terms of the error in each band:

The broadband heating rates in the range 10-1000 hPa are excellent, but at lower pressures some absorption is missing. This leads to the strength of the upper-stratosphere/mesosphere cooling being underestimated, and too much upwelling radiation from the surface escaping to space. The bandwise evaluation suggests too little absorption/emission by stratospheric water vapour in the far infrared, and to a lesser extent some missing absorption in the 15-micron CO2 band and the 9.6-micron O3 band.


PSLACKD version 5.002 uses 20 bands in the shortwave and a total of 77 g-points. The evaluation of present-day fluxes and heating rates is here:

and the evaluation in individual bands is here:

or equivalently plotted in terms of errors compared to line-by-line:

The most notable broadband error is the overestimate of surface downwelling shortwave by almst 5 W m-2, on average, which is associated with 2.5 W m-2 too much in the UV/Vis region 0.32-0.69 microns and the remainder in various of the near-IR regions. There is probably an underestimate of ozone absorption in the visible (20,000-31,000 cm-1). The underestimated mesospheric heating rate appears to be associated with missing very strong CO2 absorption.


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