Water vapour continuum absorption in mid‐latitudes: Aircraft measurements and model comparisons

Recently reported measurements by the Meteorological Research Flight C‐130 aircraft over the tropical Atlantic have shown that existing models of infrared water vapour continuum absorption underestimate its magnitude by up to 30%. This paper presents additional results from more recent measurements made close to the south‐west approaches of the British Isles and over the eastern Mediterranean Sea. These measurements are compared with two models: GENLN2, a line‐by‐line model, and the widely used band model LOWTRAN7. The measured radiances suggest a consistent underestimate in both models of the water vapour continuum absorption. The modified parametrization for the water vapour continuum absorption, inferred from the tropical results, was also used here to check its validity for lower water vapour amounts and lower temperatures. As with the tropical results, increasing the self‐broadening coefficient by a constant factor, or increasing the temperature dependence, improves the agreement between the measurements and the model predictions.