We use observations of surface and top-of-theatmosphere
(TOA) broadband radiation fluxes determined
from the Atmospheric Radiation Measurement programme
mobile facility, the Geostationary Earth Radiation Budget
(GERB) and Spinning Enhanced Visible and Infrared Imager
(SEVIRI) instruments and a range of meteorological
variables at a site in the Sahel to test the ability of the
ECMWF Integrated Forecasting System cycle 43r1 to describe
energy budget variability. The model has daily average
biases of −12 and 18 W m−2
for outgoing longwave
and reflected shortwave TOA radiation fluxes, respectively.
At the surface, the daily average bias is 12(13) W m−2
for the longwave downwelling (upwelling) radiation flux
and −21(−13) W m−2
for the shortwave downwelling (upwelling)
radiation flux. Using multivariate linear models of
observation–model differences, we attribute radiation flux
discrepancies to physical processes, and link surface and
TOA fluxes. We find that model biases in surface radiation
fluxes are mainly due to a low bias in ice water path (IWP),
poor description of surface albedo and model–observation
differences in surface temperature. We also attribute observed
discrepancies in the radiation fluxes, particularly during
the dry season, to the misrepresentation of aerosol fields
in the model from use of a climatology instead of a dynamic
approach. At the TOA, the low IWP impacts the amount of
reflected shortwave radiation while biases in outgoing longwave
radiation are additionally coupled to discrepancies in
the surface upwelling longwave flux and atmospheric humidity