Evaluating and improving CLM hydrologic processes for integrated earth system modeling at regional scales

The community land model (CLM) was designed for coupling with atmospheric models to simulate water, energy, and carbon fluxes between the land surface and atmosphere. These fluxes are regulated in various degrees by its hydrologic processes, which have not been vigorously evaluated for applications at watershed or regional scales. In the framework of an integrated regional earth system model being developed, accurate hydrologic information in all of its components including socio-economy, atmosphere, land, and energy infrastructure is needed to represent the interactions between human and earth system processes. Applying CLM in this framework requires evaluation and model improvement so that CLM could be used to represent hydrology, soil, managed and unmanaged ecosystems, and biogeochemical processes across scales in a single modeling framework. In this presentation, we will report preliminary results on the development of CLM featuring: (1) improved land surface hydrology that incorporates hydrologic processes from the Variable Infiltration Capacity (VIC) land surface model, including the parameterizations of subgrid variability, dynamic surface- and groundwater interactions, and hydraulic redistribution; (2) a semi-distributed extension of CLM (DCLM) for more spatially-explicit hydrologic modeling, which is critical for regional land and water management decisions under climate change mitigation and adaptation scenarios. The model development will be evaluated at flux towers and watersheds at various scales.