Ammonia Emissions in the US: Assessing the Role of Bi-directional Ammonia Transport Using the Community Multi-scale Air Quality (CMAQ) Model

Abstract

A pilot study assessing bi-directional ammonia (NH3) transport using the Community Multi-scale Air Quality (CMAQ) Model for the Eastern United States (US) is underway. The study develops and tests bi-directional flux algorithms, explores methods of providing agricultural fertilizer information into CMAQ, and clarifies possible NH3, and overall one-atmosphere, chemical budget changes with the full implementation of the bi-directional flux option planned for the 2011 CMAQ release. One focus area is the adjustment of the current CMAQ bi-directional flux module to include a dynamic soil emission potential component. The soil emission potential (Γg) is calculated offline using commercial fertilizer application survey data from the National Nutrient Loss & Soil Carbon (NNLSC) Database and is then input to CMAQ for computation of the NH3 air-soil compensation point and subsequent NH3 flux. A full 2002 year model run over the standard CMAQ (v. 4.7) Eastern US domain incorporating the revised bi-directional flux module is planned.