Current
Status:
•Soil moisture,
skin temperature, and snow assimilation are underway.
•Land Data
Assimilation Systems (LDAS) show promise in operational large-scale settings.
Data
Assimilation Tradeoffs:
•Tradeoff between
using complex data assimilation techniques and the ability to use all the available data due to the large computational burdens.
•Tradeoff between
1D and 3D data assimilation methods.
•Tradeoff between fine resolution and large area implementation.
•Data assimilation has the potential to downscale assimilated observations using spatial variability information extracted from other sources.
Land
Surface Data Assimilation Realities
•Large-scale land
data assimilation is severely limited by a lack of observations.
•Most land
observations are only available at the surface, meaning that biased differences in
surface observations and predictions can be
improperly propagated to depth.
•Assimilation does not always make everything in the model better. In the case of skin temperature
assimilation into an uncoupled model, biased air temperatures caused
unreasonable near surface gradients to occur using assimilation that
lead to questionable surface fluxes.