Cloud characteristics and channel selection for IASI radiances in meteorologically sensitive areas.

• Main Authors: Nadia Fourrié, Florence Rabier
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2004
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1084.9737; http://cimss.ssec.wisc.edu/itwg/itsc/itsc13/proceedings/posters/b21_fourrie.pdf

Introduction Advanced infrared sounders, such as the Atmospheric InfraRed Sounder (AIRS, launched on board the Aqua satellite in May 2002) and the Infrared Atmospheric Sounding Interferometer (IASI) scheduled to be on board the first operational European polar-orbiting satellite Metop, measure or will measure radiation in many thousands of channels. They have the potential to provide atmospheric temperature and composition information at a much higher vertical resolution and accuracy that can be achieved with the previous generation of satellite instruments such as the High resolution Infrared Radiation Sounder. As it is neither feasible nor efficient to assimilate all the channels in a Numerical Weather Prediction (NWP) system, channel selection policies have been designed in the NWP context. Previous studies have proposed methods in order to reduce the number of channels to keep only the ones, which bring the most useful information. In particular If such advanced sounders have to lead to a very significant impact on the forecast quality, one should address in details the question of retaining the most information possible in the sensitive areas. Previous studies such as those of The first objective of this study is also to study the cloud cover and the cloud top level, but from the satellite imager AVHRR (Advanced Very High Resolution Radiometer) in simulated IASI pixels. This is done over the North Atlantic Ocean for cases of FASTEX (Front and Atlantic Storm-Track Experiment, Joly et al. 1999), and more particularly in the sensitive areas for the forecasts of storms of 8 Intensive Observing Periods (IOP). Once the cloud characteristics of the sensitive areas will be established, the robustness of the iterative channel selection method used by The next section presents the study of the cloudiness in the meteorological sensitive areas for the 8 FASTEX IOPs. The description of the channel selection framework and results obtained in a simple context of perfect observations for profiles with cloud top level at ...