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2013
Presentation
Titel
Validation of clouds modeled by MATISSE code, with MODIS satellite images
Titel Supplements
Presentation held at ITBMS 2013, 9th International IR Target and Background Modeling & Simulation Workshop, 10-13 June 2013, Toulouse, France
Abstract
Available satellite images in different spectral bands, provided for instance from the MODIS sensor, are of good interest for remote sensing applications. The simulation of backgrounds is also essential for many applications, as to complete spectral information, types of backgrounds and climates, or geometrical configurations. The software MATISSE (Advanced Modelling of the Earth for Environment and Scenes Simulation) developed by ONERA is an appropriate tool for computing natural background spectral radiance images including atmosphere, sea and land. Validations have already been conducted concerning sea radiances and radiances of different ground cover types. In order to go further with the validation process, the simulation of clouds has been investigated. In imagery mode, MATISSE can only model stratocumulus type of clouds, but in Line-of-Sight mode a more complete data base is included in the code. To validate the cloud radiance levels, a comparison between a MODIS image - selected and analysed by Fraunhofer IOSB concerning the presence of various cloud types - and clouds resulting from MATISSE computations was carried out. The chosen wavelength is close to 4?m, so thermal effects are predominating. As the natural variability of clouds is very large, a research of context data for describing the weather conditions during the day of the MODIS measurements has been performed: radiosounding data, temperature, clouds types and altitudes could be identified as far as possible for the analysed areas. Six different clouds have been observed on the MODIS image comprising low, medium and high levels. For every cloud, several MATISSE computation cases have been performed and an envelope of results is presented around the average values of the measurements. It has been shown that the best comparisons generally correspond to environment data deduced from context data. By taking into account the characteristics of the MODIS sensor and its image acquisition process, a simulated image for clear sky conditions has been modeled with MATISSE by Fraunhofer IOSB and was completed with boxes corresponding to cloudy conditions by ONERA. The results show a good agreement of modeled and measured images.