Improved capabilities of the Chinese high-resolution remote sensing satellite GF-1 for monitoring suspended particulate matter (SPM) in inland waters: Radiometric and spatial considerations

Dominated by high dynamic and small-scale variability, remote sensing of inland or coastal waters is frequently impended by insufficient spatial resolutions from conventional ocean color sensors. With the urgent need and the rapid progress in high-resolution earth observation systems (HR), it is critical to assess the capabilities of HR in inland water monitoring. In this study, the radiometric and spatial performance of the Chinese high-resolution GF-1 Wide Field Imager (WFI) data for water quality monitoring were evaluated in term of the signal-to-noise ratio (SNR), sensitivity to suspended particulate matter (SPM) variations and spatial depiction ability. The SNR was statistically estimated from variable moving window method, and the radiometric sensitivity was simulated using the Moderate Resolution Atmospheric Transmission (MODTRAN) under varied surface and atmospheric conditions. Results indicated that both the SNR and the radiometric sensitivity of the GF-1 WFI were enhanced by 3-5 times than its predecessor (Chinese HJ-1 CCD) or Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and were comparable to Landsat 8 Operational Land Imager (OLI) and Moderate Resolution Imaging Spectroradiometer (MODIS) medium-resolution bands (250 and 500 m), which have been extensively applied in inland water environment monitoring. Cross comparisons demonstrated high consistency of the spatial distribution and concentration of SPM maps between GF-1 WFI and Landsat 8 OLI Furthermore, more than 75% of the spatial variations in high turbid waters were resolved from GF-1 WFI data, whereas the ability dropped to 40% when the spatial resolution was degraded to 250 m (MODIS-like sensors). Overall, GF-1 WFI is extraordinarily promising with an enhanced SNR, an increased spectral sensitivity to SPM variations and an advanced spatial resolution. With the ongoing plans of the successive GF series (2-7), the findings would serve as a reference for forthcoming applications, and are critical for future satellite missions. (C) 2015 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved.