Validation of MODIS-based monitoring for a green tide in the Yellow Sea with the aid of unmanned aerial vehicle

Abstract

Abstract. Previous studies have shown that Terra moderate resolution imaging spectroradiometer (MODIS) has low detection and characterization efficiency when mapping a green tide (Ulva prolifera) in the Yellow Sea. To quantify the uncertainty in mapping of the green tide using MODIS data, comparisons were conducted between quasi synchronous MODIS images and in situ observation data, as well as an unmanned aerial vehicle (UAV) image. The results show that MODIS images could detect the location of large (>100 m) floating green algae patches with good positional accuracy but tended to ignore the existence of small patches less than 10 m in width. The floating macroalgae area extracted using MODIS was several times larger than the area mapped using the UAV image. The Sentinel-2 multispectral instrument, the Chinese highresolution GF-1 wide field camera, and the Chinese HJ-1 charge-coupled device are recommended for early green tide detection, whereas MODIS is suitable for green tide monitoring. The UAV could also play an important role in regional green tide monitoring with the advantages of flexibility, smaller dimensions, high spatial resolution, and low cost.

Uncrewed Aerial Systems in Water Resource Management and Monitoring: A Review of Sensors, Applications, Software, and Issues

“…UAS can be used for coastal zone mapping [232], coastal fooding monitoring [142,149], river deltas [151], tidal reefs [148], dynamic tidal inlets [8,233], sea-level rise [230], surveying of coastal structures [234], sea-level rise scenario simulation [142], analysis of shoreline changes [9], and beach sediment changes [151]. Te drone survey was used to validate satellite monitoring of the Yellow Sea green tide disaster [235]. Similarly, a study [150] to estimate the algal biomass in the Yellow Sea was conducted using UAV data and satellite imagery.…”

A UAV and S2A data-based estimation of the initial biomass of green algae in the South Yellow Sea

“…Many scholars have monitored red tide by UAV, and obtained satisfactory effect (Shang et al, 2017). Xu et al (2017) conducted real-time monitoring over the floating green tide for regional green tide monitoring and management by UAV. But there is still little report on how UAV is used for monitoring studies on raftattaching green algae.…”

Research on the dissipation of green tide and its influencing factors in the Yellow Sea based on Google Earth Engine

“…The solid lines of different colors are the boundaries around areas covered by green tide on different dates; colors define chronology, in the following order: black, blue, purple, yellow, and red. Panel (b) Superimposition of green tide at the observation points on 19th May 2016(Xu et al, 2017), numbers above the dots represent the magnitude levels of green tide patches at the field observation sites (see supplementary Table1). Panel (c) is the division of green tide stage.…”