Development, importance, and effect of a ground truth correction for the Moon Mineralogy Mapper reflectance data set

[1] We evaluate the effect and importance of a ground truth correction for the Moon Mineralogy Mapper (M) level 2 (reflectance) data set. This correction is derived from extensive laboratory characterizations of mature feldspathic lunar soils and is designed to improve the accuracy of 1mm absorption features in M reflectance data. To evaluate the correction, the band strength across a subset of the feldspathic highlands terrane (FHT) is analyzed with M imaging spectroscopy data. Using M reflectance data and derived products, we find significant differences in band strength and shape between M observations collected over identical terrain but under different observational and operational conditions. The ground truth correction minimizes these differences in 1mm band strengths and also brings the 1mm band strengths measured with M data into closer agreement with laboratory measurements of lunar soil samples. Although the FHT region studied was found to have very low band strengths, the M ground truth correction results in overall stronger absorption features for all mature soils relative to uncorrected level 2 (reflectance) data for the same region. These differences between M data collected under different operational conditions and the effects of the ground truth correction, while minor in appearance, can have significant implications for interpretations of any regional soil analyses withM data that rely on absolute 1mm absorption feature strength. The M ground truth correction corrects only wavelengths below ~1500nm, and comparisons between corrected and uncorrected wavelengths must be done with caution.