Abstract:
The availability of coarse-scale satellite images has raised interest in assimilating these products to improve fine-scale land surface state estimates. Coarse observations can be disaggregated or re-gridded to the modeling scale prior to assimilation or within the assimilation procedure. With a few exceptions, snow data assimilation efforts have been limited to 1D filtering, i.e. the observations and model units were at or brought to the scale of the model grid and assimilated independently for each grid cell. This study compares different alternatives to assimilating synthetic Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) snow water equivalent (SWE) into fine scale (1 km) Noah land surface model simulations, either after disaggregation (re-gridding) to the fine-scale model resolution prior to data assimilation or directly using an observation operator for mapping between the coarse and fine scales. In either case observations are assimilated either simultaneously or independently for each location.