COMPETENCE OF SAR IMA

5. COMPETENCE OF SAR IMA

SPILL DETECTI The problem of pollution of the oceanic wat oil materials is presently considered as one As first step for solution of the oil spill re using airborne and spaceborne remote se surveillance of the sea surface. Such system all-weather observation, be independent fro conditions and cloud cover, define the volume of oil spill and work in real scale of aperture radar SAR is independent of illumination conditions and allow to acquire and night under cloud cover that is an ad remote sensing sensors. SAR is an active remote sensing tool in wh satellite transmits microwave signals tow surface, SAR signal after interaction with the to the antenna [22]. The interaction between microwaves is very sensitive to variatio roughness. Rough surfaces scatter large amo to the antenna and have bright signatures wh reflect the energy away from the anten signatures. It is well-known, that crude substances form films of various thicknesses Oil films locally damp sea surface roughn signatures, so-called slicks, on the SAR im look on the SAR images as dark patch surrounding surface. During the lifetime of oil spill in the sea it number of processes, which dramatically chemical properties. Called by term weatheri are as follows: spreading, drift, evapo emulsification, bacterial degradation and ph With time the physical-chemical propertie changed due to effect of these processes. Th important role in oil spill detection by using but relative importance of each process is n It is also reported that the thick part of oil only 10 of spill area, while remaining oil c an area as blue shine [22]. The detectability of oil slicksspills in SA depends on the wind speed at the sea surfac speeds, typically between 0 and 2-3 ms, th dark on SAR images. In this case the wind-g not already developed and oil films look background, - detection in this case is impo between 3 and 6 ms is ideal for oil slick surface roughness is developed and oil sli patches on a bright background. However, reaches 10-12 ms, detectability is im obstructed due to the redistribution of oil surface waves and wind-induced mixing i layer [23]. as a result slick disappears from SAR imagery. Other detection problem is discrimination and natural organic oil slicks [8]. Natural very small thickness resulting from life-cyc other marine organisms can form surface surface and, in turn, produce similar dark sig images [7]. Experiments conducted with mu polarization SIR-CX aboard the space shu F AGERY FOR OIL TION aters by crude oil and ne of the most sharp. l response problem is sensing systems for tem must provide the from of illumination e position, type and of time [24]. Synthetic of weather and sun uire SAR images day advantage over other which an antenna on a toward to the ocean the sea surface returns en the sea surface and tions in sea surface mount of energy back while smooth surfaces tenna and have dark de oil and other oil ses on the sea surface. ghness and give dark R images [9];[8], they tches among brighter it will be expose to a ly influence physical- ering, these processes aporation, dispersion, photo oxidation [12]. rties of oil spills are . These processes play ing space borne SAR, s not well understood. il film usually covers il covers up to 90 of SAR images strongly rface. Under low wind , the sea surface looks d-generated waves are ooks dark on a dark possible. Wind speed ick detection, the sea slicks appear as dark er, when wind speed impossible again or il spillsslicks by the g in the upper ocean m the sea surface and n between man-made ral biogenic films of a cycle of plankton and ce slicks on the sea signatures on the SAR multi-frequencymulti- shuttle [16]; [7], as expected could provide more relia discrimination.

6. METHO