The Applicability of Remote Sensing Techniques for 0il Slick Detection
Authors: Catoe Clarence E. 
Published: October 2008

A discussion of the applicability of various remote sensing techniques to the detection, the identification, the thickness measurements, and the mapping of oil films on the surface of the water is furnished. In this report a comprehensive survey of the state-of the- art of various remote sensing techniques that make use of both the spectral and the spatial dimensions of remote sensing are given. The remote sensing techniques considered are arranged into two defined categories, namely, imaging techniques and nominating techniques. The remote sensing techniques investigated cover the gamut to the ultraviolet, visible, infrared and microwave portions of the electromagnetic spectrum. Short reviews covering the theoretical basis of the various sensing techniques, as far as the detection mechanism is concerned, are supplied. Specifically, each technique is analyzed from the point of view of its weather capabilities, kinds of data obtained, and quantity of information gathered. In addition, where possible, laboratory and field test data on the response of the various sensors that operate in either the passive or active mode, or oth, are indicated.

From the information obtained, it is obvious that no one sensor can detect, identify, measure thickness and map oil slicks. What is required is a multi spectral approach to resolve this sensing problem.

Introduction

The Coast Guard, in discharging its responsibility, spends a considerable amount of time and effort monitoring our waters to detect oil leaks or spills. In most instances, the determination of oil spills has been made by visual sightings. However, it is recognized that human vision is not entirely adequate for the job of detecting oil slicks, and the Coast Guard is evaluating other sensors to determine their usefulness for the detection and surveillance of oil.

The bulk of the private and government attention in this area of oil pollution has been devoted to developing regulations, methods and procedures to reduce the probability of oil spillage. Additional effort is being expended to develop cleanup techniques and equipment to control oil that is accidentally spilled and then reported to the proper authorities. In any event, it is reasonable to assume that in spite of new regulations and preventive measures there will still be oil spills, either due to human carelessness or calamities beyond human control, that will not be reported in a timely manner. What is needed to combat unreported incidents are effective techniques for remote all-weather detection and surveillance of oil slicks in sufficient time so that adequate countermeasures can be utilized to minimize the possible pollution hazards to the coastal and inland waters of the U. S. and to detect violators of U. S. and international laws concerning pollution of the sea by oil.

The initial effort in the area of oil detection by the Applied Technology Div. has been centered on the question, "Does oil have a unique signature which enables one to differentiate between it and other pollutants?" (a signature being a particular characteristic of the target that enables one to distinguish it from its background or other targets). At the present time, it is known that oils do exhibit characteristic signatures. However, their electromagnetic characteristics may vary with time and environmental conditions, a fact which may help or hinder detection, depending on how well the phenomenon is understood.