Land–Snow–Waterbody 2-Endmember-Mixed-Pixel Effect on the Measurement Error of the Moon-Based Earth Radiation Observatory

The Moon-based Earth Radiation Observatory (MERO) has the potential to complement current Earth Radiation Budget (ERB) missions by providing higher temporal resolution data, especially for the Earth’s polar regions. Regarding the MERO mission design, quantifying its mixed-pixel-induced uncertainty is crucial, which occupies an important part in the MERO inherent systematic errors. However, current knowledge about this MERO mixed-pixel-induced uncertainty is still limited. In this study, we proposed a MERO 2-endmember-mixed-pixel error quantification method and explored such errors in the land–snow, land–waterbody, and waterbody–snow mixing scenarios. Results indicate that the land–snow mixing leads to the biggest measurement errors, which are as large as 4.02% and 7.98% for the Earth’s top of the atmosphere (TOA) outgoing solar-reflected shortwave radiation (OSR) and outgoing thermally emitted longwave radiation (OLR) fluxes, respectively. The waterbody–snow mixing caused the second largest measurement error with a TOA OSR maximum of 3.01% and TOA OLR maximum of 7.08%. The land–waterbody mixing results in the least measurement error with a TOA OSR maximum of 0.79% and a TOA OLR maximum of 0.41%.