Detecting the Great Pacific Garbage Patch floating plastic litter using WorldView-3 satellite imagery.

Area of Science:

• Environmental Science
• Remote Sensing
• Oceanography

Background:

• Floating plastic debris poses a significant threat to marine ecosystems.
• Accurate mapping and monitoring of plastic accumulation zones like the Great Pacific Garbage Patch (GPGP) are crucial for effective mitigation strategies.

Purpose of the Study:

• To develop and validate a novel proxy-based approach for detecting and semi-quantitatively observing floating plastic litter in the GPGP.
• To assess the feasibility of using high-resolution satellite imagery for plastic pollution monitoring.

Main Methods:

• Utilized 2018 WorldView-3 satellite imagery with very high geospatial resolution and 8 wavebands.
• Defined a spectral anomaly proxy by subtracting ocean water background reflectance from top-of-the-atmosphere reflectance.
• Validated 'suspected plastics' by comparing spectral shapes and anomalies with a known plastic reference target (The Ocean Cleanup System 001 Wilson) and direct visual observations.

Main Results:

• Successfully identified 'suspected plastics' by detecting spectral anomalies consistent with known plastic signatures.
• Demonstrated the effectiveness of the proxy-based approach in qualitatively and semi-quantitatively observing floating plastic litter.
• Confirmed findings through direct observations in true color composite images.

Conclusions:

• The developed proxy-based method offers a promising approach for detecting floating plastic pollution in marine environments.
• This technique has potential for operational monitoring applications, particularly with the advent of regular Sentinel-2 imaging over the GPGP.
• Future work will involve validation with numerical models and net trawling surveys to refine mapping capabilities.