Assessment of large-scale water storage dynamics in the Community Land Model

Abstract:

A fundamental task of the Community Land Model (CLM; the land component
of the Community Earth System Model) is the partitioning of
precipitation into evapotranspiration (ET), runoff, and water storage.
Testing model performance against site-level observations provides
important insight, but can be challenging to extrapolate to the
larger spatial scales at which Earth System models typically operate. 
Traditionally, measurements of river discharge have provided the best,
and in many cases only, metrics with which to assess the performance
of land models at large spatial scales (i.e. regional to continental scale
river basins). Because the quantity of discharge measurements has
declined globally, and the human modification and management of rivers
has increased, new methods of testing land model performance are needed. 
As global observations of total water storage (TWS) and ET have become
available, the potential for direct assessment of the quality of the
simulated water budget exists. In this presentation, we use TWS
observations from the GRACE satellite project and upscaled flux tower
measurements from the FLUXNET-MTE dataset to assess the performance of CLM
parameterizations such as canopy interception, storage, and evaporation,
soil evaporation, and soil moisture and groundwater dynamics. We then
give examples of alternative model parameterizations, and show how
these parameterizations improve model performance relative to GRACE and
FLUXNET-MTE based metrics.