Is Ocean Reflectance Acquired by Citizen Scientists Robust for Science Applications?

Abstract

Monitoring the dynamics of the productivity of ocean water and how it affects fisheries is essential for management. It requires data on proper spatial and temporal scales, which can be provided by operational ocean colour satellites. However, accurate productivity data from ocean colour imagery is only possible with proper validation of, for instance, the atmospheric correction applied to the images. In situ water reflectance data are of great value due to the requirements for validation and reflectance is traditionally measured with the Surface Acquisition System (SAS) solar tracker system. Recently, an application for mobile devices, "HydroColor", was developed to acquire water reflectance data. We examined the accuracy of the water reflectance measures acquired by HydroColor with the help of both trained and untrained citizens, under different environmental conditions. We used water reflectance data acquired by SAS solar tracker and by HydroColor onboard the BC ferry Queen of Oak Bay from July to September 2016. Monte Carlo permutation F tests were used to assess whether the differences between measurements collected by SAS solar tracker and HydroColor with citizens were significant. Results showed that citizen HydroColor measurements were accurate in red, green, and blue bands, as well as red/green and red/blue ratios under different environmental conditions. In addition, we found that a trained citizen obtained higher quality HydroColor data especially under clear skies at noon.

An Evaluation of Citizen Science Smartphone Apps for Inland Water Quality Assessment

“…Because the whole concept of HC is physically sound, it certainly has the potential to become a key smartphone app for water managers. However, we suggest some further investigation, based on our field campaign and the results presented in [32][33][34]. Variation in the smartphone-derived Rrs (RGB) values may be expected due to the viewing geometry, detectors and spectral band-pass function used to record the amount of electromagnetic radiation and smartphone settings and processing methods of images.…”

“…It has been calibrated and tested in Dutch inland waters with a large diversity in composition [31]. The HC App (http://misclab.umeoce.maine.edu/research/HydroColor.php) was tested extensively in both coastal and inland US waters [32] and British Columbia [33]. Besides a limited test in the Kesses Dam, Kenya [34], a systematic comparison of both Apps has not been published.…”

Measurement of Water Leaving Reflectance Using a Digital Camera Based on Multiple Reflectance Reference Cards

“…The accuracy of HydroColor was lower when the surrounding water environment was complex. Yang et al [ 22 ] applied HydroColor to the coast of western Canada, and data were collected by both trained and untrained citizens. The results demonstrated that HydroColor is more effectively utilized by trained individuals and that its accuracy is higher when there is no cloud cover.…”

Model-Observations Synergy in the Coastal Ocean

“…Finally, coastal areas are ideal in engaging the public in current scientific challenges and raise their awareness on global environmental concerns of immense importance, including global warming and plastic pollution (Cigliano et al, 2015). Citizen science data collected in coastal areas have reached the quality appropriate for exploitation in marine policy (Hyder et al, 2015), coastal area monitoring (Brewin et al, 2015(Brewin et al, , 2017b and scientific studies (e.g., for the evaluation of satellite data in coastal regions, Brewin et al, 2017a;Yang et al, 2018). Citizen science data can cover areas that are typically under-sampled by traditional monitoring networks (e.g., intertidal zone) and may offer new opportunities for a quantitative evaluation or assimilation into coastal models.…”