The impact of assimilating hyperspectral infrared water vapor channels in numerical weather prediction

In some earlier studies, through careful selection and use of hyperspectral water vapor channels, benefits have been seen in analysed and forecast moisture fields. These assimilation techniques are currently being developed to further enhance the methodology to exploit the hyperspectral water vapor channels in Numerical Weather Prediction. There are several problems which must be resolved in using these channels. In general, the non-linearity of the water vapor channels makes them difficult to assimilate. Channels which have significant dependencies on water vapor in the stratosphere are not yet used by most NWP centers. We have conducted a number of experiments focused on using water vapor channels, first which provide information in the troposphere and then in the stratosphere. Our focus is on identifying and quantifying changes occurring in the upper troposphere and stratosphere. We will show humidity and temperature changes associated with the assimilation of these channels and look at the influence these changes have on subsequent forecast fields.