PR-312-18208-E02 PRCI White Paper PVMRM Theoretical Issues and Recommended Solutions

This white paper demonstrates that AERMOD contains formulation errors and does not currently provide accurate NOx estimates for sources (e.g., natural gas compressor stations) with shorter stacks. The white paper also demonstrates that a new building downwash theory (PRIME2) does provide better agreement with NOx observations than AERMOD's PRIME algorithms. In addition, the white paper shows that PVMRM does not provide accurate estimates of the NO2/NOx ratio as confirmed by Panek et al. (2020) who showed poor agreement between predicted and observed NO2/NOx ratios. The paper concludes that the basic theory in PVMRM is sound, but some underlying simplifying assumptions contribute to model performance issues.