Intercomparison of #thermal #remotesensing #evaporation models revealed the pressing need of refinements in aerodynamic resistance parameterization

Congratulations to Ivonne Trebs for leading our study that got published in the special issue of thermal remote sensing in the Remote Sensing of Environment. The study investigated the influence of aerodynamic resistance (ra) and its relation to land surface temperature (LST) uncertainties on the performance of three structurally different evaporation (E) models (SPARSE, STIC and SEBS). It used meteorological observations from different xeric and mesic ecosystems in Australian ecological transect in conjunction with MODIS Terra-Aqua LST and leaf area index (LAI) products.

Our results revealed, (1) an overestimation tendency of evaporation by all three models in the water-limited xeric ecosystems by up to 50% on average, which was caused by an underestimation of sensible heat flux (H); (2) overestimation of evaporation was associated with discrepancies in ra retrievals under high atmospheric instability, during which errors in LST (expressed as the difference between MODIS LST and in-situ LST) apparently played a minor role; (3) the impact of ra on the evaporation retrieval error was found to be of the same magnitude as the influence LST errors in the xeric ecosystems as indicated by variable importance in projection (VIP) coefficients from partial least squares regression above unity; (4) mesic ecosystems indicated minor dependency on ra for modelling evaporation, which was due to a higher roughness length and lower LST resulting in the dominance of mechanically generated turbulence, thereby diminishing the importance of buoyancy production for the determination of ra.