Detecting Floating Plastic Marine Debris using Sentinel-2 Data via Modified Infrared NDVI

Floating marine debris is one of the significant marine pollutions that affect many living on the globe. Thanks to satellite technology, the Earth observation satellite has mostly constant frequency and wide area coverage. Moreover, some observation data are also openly and freely accessible for everyone, such as Sentinel platforms' data. However, most floating debris is difficult to observe by the above platform because it often has a smaller size than the highest spatial resolution of the Sentinel data. In this paper, we propose the method for detecting the floating marine debris via the Sentinel-2 data. The infrared normalized difference vegetation index (INDVI) was modified to increase plastic debris detection capability. The narrow near-infrared band (band 8A) was replaced by the highest near-infrared band (band 8). Two individual formulas of the modified version were proposed due to the INDVI is an empirical formula dependent on each platform sensor. The known targets of the floating plastic aggregation from two valuable experiments at Tsamakia beach, Greece, and Limassol old port, Cyprus, were used to observe and evaluate the detectable capability. The Signal to Noise Ratio (SNR) was applied to indicate our method performance compared with many recent methods of floating plastic debris detection. The results show that our proposed method can be well used to detect floating aggregated plastic objects, although it has a small size than the Sentinel-2 spatial resolution. Besides, it can also observe some floating plastic patches that are difficult to notice by visible optical information.