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CONSISTENT USE OF THE KALMAN FILTER IN CHEMICAL TRANSPORT MODELS (CTMS) FOR DEDUCING EMISSIONS
Citation:
Gilliland, A B. CONSISTENT USE OF THE KALMAN FILTER IN CHEMICAL TRANSPORT MODELS (CTMS) FOR DEDUCING EMISSIONS. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES 106(D16):17,939-17,952, (2001).
Impact/Purpose:
This task has the following objectives:
Improve modelers' ability to focus on scientific and policy issues in modeling studies by providing software that supports composing, applying, and evaluating complex systems of models.
Improve the understanding of the interaction of the atmosphere and the underlying surface, especially the flux of mass in both directions, and EPA's ability to simulate that interaction.
Contribute to multimedia studies and assessments by applying state-of-the-art atmospheric models, estimating atmospheric contributions to multimedia issues and the sources of those contributions, and evaluating the models' strengths and weaknesses.
Description:
Past research has shown that emissions can be deduced using observed concentrations of a chemical, a Chemical Transport Model (CTM), and the Kalman filter in an inverse modeling application. An expression was derived for the relationship between the "observable" (i.e., the concentration) and the "internal" state (i.e., emissions) in order to implement the Kalman filter with a CTM for emission deduction. Only the final version of the equation is usually presented when the results are published from this type of application. A critical assumption in the derivation is that the modeled chemical concentrations are initially the same as observed at the monitor locations. An alternative implementation of the method that includes the modeled and observed initial concentrations must be applied when this assumption cannot be justified. However, the alternative formula answers a fundamentally different question that may not provide the information usually intended for inverse modeling studies.