Assessing the Value of Each Instrumented CMAQ Model for Addressing Aerosol-related Policy Questions

SHANNON CAPPS, Jiachen Liu, Sergey Napelenok, Benjamin Murphy, Kirk Baker, Daven Henze, Armistead G. Russell, Drexel University

     Abstract Number: 420
     Working Group: Source Apportionment

Abstract
The Community Multiscale Air Quality (CMAQ) model has been augmented with sensitivity analysis and tracer approaches that assist policymakers in selecting optimal strategies for mitigating airborne particulate matter. Existing methods include the higher-order direct decoupled method (CMAQ-HDDM), the integrated source apportionment method (CMAQ-ISAM), the adjoint method (CMAQ-adjoint), and the newly developed hyperdual-step method (CMAQ-hyd). Each method is based on a unique mathematical approach, which shapes the questions most appropriately addressed by each. The CMAQ-adjoint is designed to efficiently answer questions about the spatially-varying emissions that influence a single concentration-based metric throughout a selected spatial and temporal domain while CMAQ-HDDM and CMAQ-hyd more efficiently quantify the varying temporal and spatial relative changes in pollutants due to a single set of emissions changes within a reasonable range. CMAQ-ISAM is better suited to quantify the entire contribution of selected emissions sources to resultant concentrations.

Our study is designed to demonstrate the value of each of these techniques to scientists and policy makers by applying them to understand emissions influences on ozone and particulate matter. Additionally, comparing the development and maintenance complexity along with computational efficiency will provide insight to those developing instrumented approaches for other CTMs and maintaining those in CMAQ.