Intercomparison of high spatial resolution LAI remote sensing products at forest sites

Abstract

Abstract Leaf Area Index (LAI) is a crucial biophysical parameter in terrestrial ecosystem and hydrological modeling. Although LAI intercomparisons have been extensively conducted at coarse- to medium-resolution scales, systematic multi-site evaluations of high-resolution (≤30 m) LAI products remain limited. This research compared three high-resolution LAI products from National Ecological Observatory Network (NEON) Airborne Observatory Platform Imaging Spectrometer (NIS), Sentinel-2 (S2), Global Ecosystem Dynamics Investigation (GEDI). These LAI products were also evaluated by Digital Hemispheric Photos (DHPs) measurements. Our findings show a greater consistency between GEDI and S2 ( R 2 = 0.31 at the pixel level, and R 2 = 0.69 at the site level) than that of GEDI and NIS ( R 2 = 0.12 at the pixel level, and R 2 = 0.51 at the site level). The comparison of S2 and NIS reaches a similar level of agreement at both pixel level ( R 2 = 0.26) and site level ( R 2 = 0.78). Time series analysis of GEDI and S2 LAI finds a reasonably good agreement on tracking canopy phenology. Comparisons with DHPs total LAI suggest that both S2 and GEDI can achieve a good estimation at site level. Our results suggest the potential of fusing GEDI and S2 data for improved high-resolution forest LAI mapping and monitoring despite their differences in instrument and sampling design. • Intercomparison of high-resolution LAI from multispectral, hyperspectral, and lidar sensors. • NEON airborne hyperspectral LAI shows the overall least agreement with reference datasets. • Sentinel-2 LAI and GEDI LAI have a good agreement at site level. • GEDI LAI shows the overall best agreement with in-situ total LAI.