The Challenges of Remotely Measuring Oil Slick Thickness

Abstract

The thickness of oil spills on the sea is an important but poorly studied topic. Means to measure slick thickness are reviewed. More than 30 concepts are summarized. Many of these are judged not to be viable for a variety of scientific reasons. Two means are currently available to remotely measure oil thickness, namely, passive microwave radiometry and time of acoustic travel. Microwave radiometry is commercially developed at this time. Visual means to ascertain oil thickness are restricted by physics to thicknesses smaller than those of rainbow sheens, which rarely occur on large spills, and thin sheen. One can observe that some slicks are not sheen and are probably thicker. These three thickness regimes are not useful to oil spill countermeasures, as most of the oil is contained in the thick portion of a slick, the thickness of which is unknown and ranges over several orders of magnitude. There is a continuing need to measure the thickness of oil spills. This need continues to increase with time, and further research effort is needed. Several viable concepts have been developed but require further work and verification. One of the difficulties is that ground truthing and verification methods are generally not available for most thickness measurement methods.

Retrieval of Oil–Water Mixture Ratio at Ocean Surface Using Compact Polarimetry Synthetic Aperture Radar

“…All the above efforts have been made in oil spill detection and classification. There are still many challenges in oil slick quantitative estimation, such as detection of oil thickness and water mixture ratios (or volume percentages), where progress is limited due to lack of available field measurement techniques, or knowledge about how oil thickness can be related to its distribution, oil type, water content and sea conditions [30]. Few works focus on quantitatively estimating the oil-water mixtures in oil slicks.…”

Oil Slick Volume Estimation from Combined Use of Airborne Hyperspectral and Pool Experiment Data

“…Although there is a crucial need for reliable oil slick volume estimation, still few methods are available to accurately measure oil-on-water slick thickness [1]. In the framework of NAOMI (New Advanced Observation Method Integration), a research project conducted by TOTAL and ONERA, the potential of hyperspectral images to estimate oil thickness is investigated.…”

Determination of Crude Oil Thickness at Night Using Thermal Imagery

“…Remote sensing of oil slick thickness in a marine environment is an active area of research and development [1][2][3][4][5]. Although significant advances have been made, many airborne ultraviolet, visible, near infrared (NIR) and short-wave infrared (SWIR) oil spill sensors do not work well under degraded visual environments (DVE) such as darkness, fog, smoke, and clouds, nor provide a consistent measure of extreme oil thickness.…”

“…Although significant advances have been made, many airborne ultraviolet, visible, near infrared (NIR) and short-wave infrared (SWIR) oil spill sensors do not work well under degraded visual environments (DVE) such as darkness, fog, smoke, and clouds, nor provide a consistent measure of extreme oil thickness. These electro-optic (EO) sensors can be expensive, heavy, costly and labor-intensive to operate from both the platform and the sensor payload perspective, and may provide a limited single point capability [1][2][3][4][5][6][7]. When discussing the challenges of measuring oil slick thickness, Fingas could not find consistent spectral signatures to gauge oil slick thickness [1].…”