Accuracy of SeaHawk-HawkEye Ocean color CubeSat remote sensing reflectance products in globally distributed aquatic sites

HawkEye was an ocean color instrument onboard SeaHawk, the first dedicated Ocean Color CubeSat, launched in 2018 to provide targeted high spatial resolution (∼130 m) images of open ocean, coastal, inland, and estuarine waters with eight spectral bands in the visible NIR region. This study presents the first comprehensive assessment of HawkEye standard Level-2 remote sensing reflectance (R rs ) products. A total of 51 cloud-free HawkEye scenes over 15 globally distributed inland and coastal water sites with contrasting optical conditions were found to be suitable for match-up analysis, spanning two years. Compared to R rs from ocean color component of the Aerosol Robotic Network (AERONET- OC) and in situ hyperspectral measurements from coastal Georgia waters (USA), HawkEye R rs accuracy varied between 31 and 61 % for Median Symmetric Accuracy (MdSA) depending on the wavelength. The R rs at 510 nm was the most accurate (31 % MdSA), and the accuracy decreased towards the blue bands, with 412 nm being the least accurate (61.7 % MdSA). HawkEye R rs is more accurate in low Chlorophyll-a waters compared to high Chlorophyll-a waters. HawkEye products accuracy improved with a site-specific atmospheric correction ( e.g. the Management Unit of the North Sea Mathematical Models (MUMM) correction improved results in two turbid coastal waters tested). HawkEye R rs product accuracy was comparable with ocean color sensors, OLCI, AQUA and VIIRS. These results thus indicate that HawkEye imagery is suitable for aquatic remote sensing applications. Further, the results serve as a reference and offer potential areas of improvement for future ocean color CubeSat missions. • Comprehensive analysis of SeaHawk-HawkEye ocean color CubeSat reflectance products • Matchup analysis with AERONET-OC and in situ spectra from diverse water types. • Most accurate HawkEye reflectance bands: 488 nm, 510 nm, and 556 nm • 10 % improvement in accuracy with suitable atmospheric correction. • Accuracy of HawkEye reflectance products is comparable to AQUA, VIIRS and OLCI.