A note on the occurrence of cloud in meteorologically sensitive areas and the implications for advanced infrared sounders

The geographical distribution and persistence of meteorologically sensitive areas (derived using adjoint forecast-error tracking techniques) are investigated with respect to the occurrence of cloud. Using sensitivity patterns and cloud structures simulated from the ECMWF forecast model a high degree of correlation is found which, if realistic, could limit the ability of space-based advanced infrared sounders to measure important meteorological features. The result underlines the need to develop techniques to use infrared sounder observations in the presence of cloud.