A satellite based product for studying terrestrial water and energy flux dynamics, HOLAPS

Studying terrestrial water and energy flux dynamics is important for understanding the mechanisms leading to changes in temperature and precipitation extremes. However, the non-conservation of energy and water in most products and their coarse spatial and temporal resolution hamper the study of land-atmosphere feedbacks. The combination of remote sensing data and modelling frameworks allows to greatly improve the spatial coverage and resolution of data products. Here, we investigate the performance of a new data product generated with the high-resolution land surface fluxes from satellite and reanalysis data (HOLAPS) framework. HOLAPS is a one dimensional modelling framework that solves the energy and water balance at the land surface, providing consistent surface and soil variables derived from remote sensing data and reanalysis products as forcings. HOLAPS reaches slightly better results than other ET and H products at daily scales in summer (KGE > 0.3 for ET and KGE > 0.0 for H) and during hot conditions (KGE > 0.2 for ET and KGE >-0.2 for H), while the state-of-the-art products show KGE > 0.1 for ET and KGE > -0.41 for H in summer and KGE > -0.1 for ET and KGE > -0.6 for H during hot conditions. All products evaluated here yield a reasonable performance (KGE >-0.41 at most sites) in simulating SM at the surface and in the root zone. The good performance of HOLAPS together with its inherent advantages (RS data driven, high temporal and spatial resolution, spatial and temporal continuity, soil moisture at different depths and long-term consistent evapotranspiration and sensible heat flux estimates) support its use for hydrological studies based on Earth Observations.