Optical Interpretation of Oil Emulsions in the Ocean – Part I: Laboratory Measurements and Proof-of-concept with AVIRIS Observations

Authors

Yingcheng Lu, International Institute for Earth System Science
Jing Shi, International Institute for Earth System Science
Yansha Wen, International Institute for Earth System Science
Chuanmin Hu, University of South FloridaFollow
Yang Zhou, International Institute for Earth System Science
Shaojie Sun, University of South Florida
Minwei Zhang, University of South Florida
Zhihua Mao, Second Institute of Oceanography
Yongxue Liu, International Institute for Earth System Science

Document Type

Article

Publication Date

2019

Keywords

Oil spill, Oil emulsion, Volume concentration, Oil thickness, Optical remote sensing, Reflectance, Absorption

Digital Object Identifier (DOI)

https://doi.org/10.1016/j.rse.2019.05.002

Abstract

Optical identification and quantification of various marine-spilled oils play an important role in oil spill monitoring, assessment, and response. Through weathering processes, oil may become emulsified in two forms of oil-water mixture: water in oil (WO) and oil in water (OW). These two forms of oil emulsion are significantly different in their volume concentration (oil/water ratio), physical properties (viscosity, density, thickness), and optical properties (spectral reflectance (R_u(λ), sr⁻¹), and spectral absorption (a(λ), m⁻¹)). In this study, the optical properties of both types of oil emulsion, with different volumetric concentrations, are determined from carefully prepared oil emulsion samples, with the aim of helping to interpret optical remote sensing imagery. The concentrations of stable WO and OW emulsions range from 45% to 95% and from 0.025% to 3%, respectively. They exhibit different R_u spectral shapes in the near-infrared and shortwave-infrared wavelengths, with five “-CH” molecular bonds evident in the WO emulsion spectra. R_u (600–1400 nm) of OW emulsions increases with volume concentrations from 0% to 3.0%, but R_u (600–2400 nm) of the WO emulsions decreases with volume concentrations from 45% to 100%. On the other hand, for a fixed concentration (80%), R_u (600–2400 nm) of WO emulsions increases monotonically with thicknesses of up to ~0.4 mm, beyond which R_u (600–2400 nm) no longer increases with oil thickness. The difference between the R_u spectral shapes of OW and WO emulsions, as well as the statistical relationships between volume concentrations and R_u (NIR-SWIR) and between oil thickness and R_u (NIR-SWIR), provide the basis for developing optical models to classify oil emulsion types and for quantifying oil volume from remote sensing imagery. The potential of such an application is demonstrated using hyperspectral AVIRIS imagery collected over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico (GoM).

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Remote Sensing of Environment, v. 230, art. 111183

Scholar Commons Citation

Lu, Yingcheng; Shi, Jing; Wen, Yansha; Hu, Chuanmin; Zhou, Yang; Sun, Shaojie; Zhang, Minwei; Mao, Zhihua; and Liu, Yongxue, "Optical Interpretation of Oil Emulsions in the Ocean – Part I: Laboratory Measurements and Proof-of-concept with AVIRIS Observations" (2019). Marine Science Faculty Publications. 2050.
https://digitalcommons.usf.edu/msc_facpub/2050