On the consistency of HJ-1A CCD1 and Terra/MODIS measurements for improved spatio-temporal monitoring of inland water: a case in Poyang Lake

Remote sensing monitoring of inland or coastal waters is frequently impeded by insufficient spatial and temporal coverage. Limited by small sizes of estuaries, lakes, ponds, etc., and weather conditions, conventional ocean colour sensors, including Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), are often inadequate. Medium- or higher-resolution sensors, such as the Chinese HJ-1A CCD1, provide great potential to complement the spatial-temporal gap of MODIS-like sensors, when multi-sensor and temporal consistency are achieved. This paper examines the radiometric performance of HJ-1A CCD1 over aquatic environment, in terms of the long-term radiometric stability and consistency, with reference to Terra MODIS. A high correlation is found in the remote sensing reflectance (Rrs) between these two sensors, using regression analysis of rigorously selected matching data after accurate Rayleigh scattering correction and removal of outliers. Validations using an independent data set demonstrate that both the Rayleigh-corrected Rrs and the total suspended sediment (TSS) concentration products are greatly improved in consistency of both spatial distributions and temporal trends. The results confirm the prospect of multi-sensor merging for the monitoring of inland water at higher spatial resolution and temporal coverage, and prove the potential of HJ-1 CCD to complement and substitute the observations of Terra/Aqua.