Understanding water fluxes through land, vegetation and air with coupled atmospheric and hydrologic modeling at extreme scales

Abstract

The processes that govern the quality, quantity, and movement of water resources are a multifaceted and nonlinear system of interactions between the earth, the land surface, vegetation, and the lower atmosphere. Recent advancements in computational efficiency and earth system modeling have awarded hydrologists with increasingly high resolution models of terrestrial hydrology, which are paramount to understanding and predicting these complex fluxes of moisture and energy. Extreme-scale (continental scale and above) hydrologic simulations are, in particular, of interest to the hydrologic community for numerous societal and operational applications. However, computational demand has traditionally necessitated some type of relaxed physical assumptions, usually by focusing physical realism on isolated components of the water cycle; for instance, land surface models as the lower boundary to meteorological models often simplify surface and subsurface hydrology, concentrating on the balance of radiation and surface turbulent fluxes but neglecting deep and lateral redistribution of soil moisture. Given the growing body of literature detailing the benefits of capturing coupled system exchange of moisture and energy, there is increasing demand for large-scale, high resolution models which simulate the hydrologic cycle as an integrated whole, from bedrock to land surface to atmosphere. This dissertation presents work towards fully-coupled, high-resolution hydrologic simulations at extreme scales. In these chapters, the importance of representing dynamic groundwater and lateral subsurface moisture redistribution is shown with regard to regional atmospheric modeling. Also discussed is the fidelity, uncertainty, and application of high-resolution, coupled-system hydrologic simulations at the continental scale. This work focuses on the connection between groundwater and atmosphere, demonstrates the importance of hydrologic representation in meteorological and remote sensing applications, and implicates the use of continental-scale hydrologic models to better understand the processes that govern our invaluable water resources.