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CMAQ TRAJECTORY GRID (PHASE 2)
Project No. A-70
Leaders: D.P. Chock
R. S. MacArthur
Scope and Objective
The objective of this project is to improve grid model predictions and cost-effective attainment by reducing the CMAQ advection solver numerical diffusion error through evaluation and reconciliation of the model packets management issue. This project will complete the roll out of CMAQ-TG.
Current Status and Future Program
Dr. Peter Purcell and Dr. Daewon Byun from the University of Houston were under CRC contract to deploy the Trajectory-Grid approach of Chock and Winkler into the EPA-preferred grid model CMAQ. Known as CRC Project A-55 “Implementation of the Trajectory-Grid Advection Algorithm in CMAQ,” the document reported a “packet management issue” which remained as “the biggest obstacle to CMAQ-TG becoming competitive with the standard CMAQ.” The code was not considered adequate for public release by project conclusion. At first read of the report, the TG is not considered deployable in CMAQ. However, there are indications that TG can work well by eliminating advection solver error but requiring nominal coding for packets management.
AER was selected to conduct a timely evaluation and improvement of the TG per Dr. Purcell’s recommendation under Dr. Chock’s direction. The project will demonstrate CMAQ-TG in a modeling venue, comparing results with a standard CMAQ application. Project deliverables will include a journal article a user-ready CMAQ-TG code, and User’s Manual. The code will be made available to the public for PM and ozone attainment demonstration. AER started this project in January 2008. AER is reporting test model results against prior benchmark data and has identified next steps for improving the TG model.
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