Data Assimilation and Model Calibration

Following, and in parallel with, the code development GEM will build and test modules to compare observational data with the models. First will be tests for consistency between models, then data assimilation capabilities will be added so that the models can be calibrated and initialized using real data. Data assimilation techniques have been developed by the climate and ocean modeling community that start with a given model code, from which the ``adjoint model'' is calculated. The adjoint can be run backwards in time, beginning with current data, to predict the original initial and boundary conditions that led to the current conditions. This computational procedure allows a subset of model variables to be adjusted so that both initial conditions, historical observations, and current data can all be optimally matched. Field data of interest include GPS, InSAR and broadband seismic (TERRASCOPE) data, together with archived and newly developed paleoseismic information in the SCEC database.