Evaluating Scale Dependent Hydrologic Processes Using a Hyper-Resolution Global Land Surface Model at Regional-to-Local Scales

Hyper-resolution modeling at representative hill slope scales of 100 m and finer allows for significantly better representation of the effects of spatial heterogeneity in topography, soils, and vegetation on hydrological dynamics. This scale allows for the representation of processes that are sub grid to the current generation of models, such as slope and aspect effects on incoming and reflected solar radiation, and consequent effects on snowmelt, soil moisture redistribution, and evapotranspiration. Higher resolution models would also enable better representation of channel processes and would provide indications of locally inundated areas and water depths in flooded areas, as well as likelihoods of the number of people affected and critical infrastructures potentially at risk. In this study we develop an innovative method for advancing high spatial resolution simulations of the terrestrial water budget with a particular focus on terrestrial water storage (TWS) variations through the use of new scaling arguments and assimilation of gravity data. Our primary hypothesis is that the local water budget terms can be calculated with improved accuracy through the application of such scaling and assimilation methods. We have used some of these methods for simulation of the NCAR Community Land Model (CLM4.0) at spatial resolutions of 30 arc-seconds (~900m) and 3 arc-seconds (~90m) over a west-to-east transect in Northern California that includes part of the Central Valley and Sierra Nevada foothills and contains several small-scale wetland areas. We use CLM4.0 results to initially quantify and outline the effects of high-resolution model outcomes and to further develop improved hyper-resolution gravity assimilation for CLM4.0 at regional-to-local scales.