Identification of NWP humidity biases using high‐peaking water vapour channels from IASI

Abstract

AbstractHigh‐peaking water vapour channels from the Infrared Atmospheric Sounding Interferometer (IASI) have been used to diagnose biases in the Met Office short‐range forecasts of upper tropospheric humidity during the Joint Airborne IASI Validation Experiment (JAIVEx) field campaign. These biases are compared with those from the European Centre for Medium‐Range Weather Forecasts (ECMWF). The Met Office forecasts are found to be too dry relative to IASI observations and in comparison with ECMWF forecasts globally. IASI is shown to be a useful tool for investigating such biases, and subsequent changes to the Met Office data assimilation scheme have successfully reduced this forecast bias. © 2011 Royal Meteorological Society and British Crown copyright, the Met Office