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Development and Validation of Robust Satellite Techniques (RST) for Oil Spill Detection and Monitoring

The problem of oil pollution of the seas is becoming a serious worldwide threat and an increasing problem difficult to manage and control. Satellite remote sensing could be an useful tool supporting the management of marine technological hazards, especially for what concern oil discharge. Nowadays, the most reliable satellite techniques are based on SAR (Synthetic Aperture Radar) active sensors operating in the microwave region of the electromagnetic spectrum. Such methods (even if not in whatever wind condition), assure good sensitivity for oil spill detection and high spatial resolution for a detailed description of the polluted area. Unfortunately, they cannot be used for real-time monitoring at all latitudes because of a revisiting cycles which ranges from few days up to 5 weeks moving from polar to equatorial zones respectively. Passive optical sensors on board meteorological satellites could be, in principle, also used for oil spill monitoring provided that suitable data analysis techniques (still lacking) are developed. In fact, thanks to a temporal resolution which is better than of few hours (up to few minutes) and despite their lower spatial resolution (not better than 250m in the visible spectral range) they could represent the unique possibility when a timely detection is crucial in order to mitigate the damages. In this work a new satellite technique for oil spill detection and monitoring is discussed. It is based on the general RST (Robust Satellite Techniques) approach applied to AVHRR observations in the Thermal Infrared (TIR) region of the electromagnetic spectrum. The proposed approach, which exploits the analysis of multi-temporal satellite records, seems able to detect the anomalous signals on the sea due to the oil polluted areas with excellent reliability and good sensitivity in different observational conditions. The approach was applied on several events related to the different cases of oil pollution (as warfare accidents, tankers accidents, oil rigs releases, ecc.). The results so far achieved confirm the reliability of the proposed approach which promises to offer new (economically sustainable too) opportunities for building a real-time monitoring system for oil spill at the global scale. Besides, considering the increase on new research fields, that try to harmonise GIS (Geographic Information Systems) technology and different remote sensing technologies, could be a key component to create new systems and platforms to support all those final users really involved in the emergencies management and responses.

Mostra/Nascondi contenuto.
Chapter one Introduction Chapter one Introduction In last years, the environmental pollution of the sea due to oil spills, revising from different sources (oil rigs releases, illegal discharges from vessels, tanker accidents, acts of environmental warfare, etc.) still continue to be a serious environmental problem. Satellite remote sensing could be an useful tool in term of management of the risks due to oil spills and for a control and near-real time (NRT) monitoring. Many techniques exist, mainly based on the use of SAR (Synthetic Aperture Radar) sensors. SAR technology, in fact, offer several advantages (namely when weather and light conditions are unfavourable) and has been proven to be a useful tool for ocean oil spill detection. Unfortunately, such methods (besides problems which still exist in recognizing oil spill in various wind condition) can be profitably used for real-time or near real- time detection only in the polar regions. In fact, due to the variation of satellite orbit track spacing with latitude, density of observations and revisit rate strongly degrade moving from high latitudes to the equatorial zones (e.g. the revisit time for RADARSAT is about 6 and 35 days for polar and equatorial zones, respectively). Till SAR constellations (like the Italian 1 COSMO-Skymed mission and the canadian RADARSAT constellation), able to increase time repetition, will not be operative, the SAR technology cannot be used for a near real-time monitoring of these phenomena. 1 COnstellation of Small Satellites for the Mediterranean basin Observation 1

Tesi di Dottorato

Dipartimento: Dipartimento di Ingegneria e Fisica dell'ambiente

Autore: Daniele Casciello Contatta »

Composta da 154 pagine.

 

Questa tesi ha raggiunto 266 click dal 23/09/2008.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.