Utilisation du satellite NOAA 5 à la connaissance de la thermique océanique. Etude de ses variations saisonnières en Mer Ligure et de ses variations spatiales en Méditerranée

Abstract : This thesis deals with the use of the data from the VHRR (Very High Resolution Radiometer) sensor aboard the meteorological satellite NOAA 5 for oceanic dynamics. We have developed two studies: seasonal variations (chap. 2) and spatial variations (chap. 3). The study of scales from 1 to 100 km is the main originality. CHAP. 1 Problems in utilization of the infrared measurements of SST from satellite. The errors which can affect the measurements of the SST (Sea Surface Temperature) are presented. The emissivity of the sea, the reflexion on the sea surface of the downward radiation of the sky, the atmospheric absorption are evaluated. VHRR data are shown to be reliable in the study of horizontal thermal gradients. CHAP. 2 Seasonal variations of sea surface temperature in the Ligurian Sea. The climatology of the Ligurian Sea has been studied through SST derived from NOAA-VHRR data. An original method of point averaging in time series is used to identify typical seasonal variations over a yearly cycle. Statistical comparisons with sea-truth data confirm the satellite measurements. Processing of VHRR time series also reveals the influence of wind on SST distributions. Although no quantitative relationship can be established between SST and currents, satellite imagery provides a good insight into overall marine circulation in the area under study. CHAP. 3 SST derived from VHRR data and turbulence. A statistical analysis shows the turbulent character of the SST fields. From 40 to 100 km, the structure functions obey a law: D (h)~h^m, where h is the scale. If the most frequent value of m is 1 (power spectra is k^-2, where k is the wavenumber), account must be taken of occurrence of the value 0.6. Such results agree with previous studies and are not found in turbulence theories. The need for further investigations and more complete analysis with the help of the satellite TIROS N in order to increase our knowledge is indicated.
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Lucien Wald. Utilisation du satellite NOAA 5 à la connaissance de la thermique océanique. Etude de ses variations saisonnières en Mer Ligure et de ses variations spatiales en Méditerranée. Océan, Atmosphère. Université Pierre et Marie Curie - Paris VI, 1980. Français. ⟨pastel-00955880⟩

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