Seminar: Sarosh Alam Ghausi

Land-atmosphere energy and water exchanges play a critical role in shaping terrestrial climate. These exchanges are primarily governed by radiation but are also influenced by antecedent hydrological conditions at both the surface (soil water) and atmosphere (VPD). In this talk, I will present an approach that uses energetic constraints to derive functional relationships between soil-water stress and vapor pressure deficit (VPD) based solely on observed radiative and surface-evaporative conditions, requiring no free parameters. We do this by accounting for the energy-balance at the surface, heat storage variations within the lower atmosphere and explicitly constraining vertical turbulent exchange using the thermodynamic limit of maximum power. This approach effectively reproduces observations, with residual errors comparable to reanalysis data. Finally, I will demonstrate its application in understanding how soil water and VPD influence ecosystem-scale evaporation.