Bringing climate models into agreement with observations of atmospheric absorption

Abstract A comparison of the output of two data assimilation models with a quasi-global, multiyear set of monthly mean observations shows that the models underestimate the amount of solar energy absorbed in the atmosphere by 15–30 W m−2, out of a total of ∼80 W m−2. In addition, observations show a much stronger dependence of absorption on column water vapor than models. Here the author analyzes absorption measured between two aircraft on a clear day during the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE) and finds a similarly strong dependence of absorption on water vapor. This common feature, in disparate types of observations, suggests the possible existence of appreciable continuum absorption in the water vapor spectrum. Various formulations of continuum absorption are tested against the aircraft observations and against the monthly mean dataset. In both cases, the addition of continuum absorption brings the models substantially closer to the observations, especially i...

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