Clouds

The main research activities of IMAA Satellite Atmospheric Physics Group are cloud detection , cloud parameters retrievals and precipitation estimations.

The IMAA research activity in the cloud detections is mainly devoted to develop new algorithms for different instruments (HIRS/3, IASI, AIRS, SEVIRI) based only on satellite data. Physical, statistical and temporal approaches have been explored in order to improve the detection of cirrus and of very low clouds. The physical algorithm consists of a series of multi-spectral dynamic threshold tests. The statistical algorithm is a pattern recognition technique which uses textural and spectral features calculated for infrared and visible images. The temporal test, used only for sensors with high temporal resolution as MSG/SEVIRI, is a pattern recognition technique which uses as inputs the spectral and textural features calculated in a 3×3 “temporal” box whose elements belong to three subsequent images.

A technique based on multispectral satellite observations is proposed to improve the retrieval of cloud parameters for single and multilayered clouds. The technique combines satellite data measured by the Atmospheric Infrared Radiation Sounder, the Advanced Microwave Sounding Unit-A/B, and the Moderate Resolution Imaging Spectrometer. Cloud properties, such as top heights (CTH) and base heights (CBH), integrated water vapour (IWV), liquid water path (LWP), and ice water path (IWP), are estimated for a variety of scenes, including multilayered cloud cases. The proposed technique shows significant improvements, especially in the presence of multiple cloud layers.