Enhanced representation of soil NO emissions in the Community Multiscale Air Quality (CMAQ) model version 5.0.2

Quazi Z Rasool,Jesse O Bash,Rui Zhang,Daniel S Cohan,Ellen J Cooter,Lok N Lamsal,Benjamin Lash

doi:10.5194/gmd-9-3177-2016

Abstract

Abstract. Modeling of soil nitric oxide (NO) emissions is highly uncertain and may misrepresent its spatial and temporal distribution. This study builds upon a recently introduced parameterization to improve the timing and spatial distribution of soil NO emission estimates in the Community Multiscale Air Quality (CMAQ) model. The parameterization considers soil parameters, meteorology, land use, and mineral nitrogen (N) availability to estimate NO emissions. We incorporate daily year-specific fertilizer data from the Environmental Policy Integrated Climate (EPIC) agricultural model to replace the annual generic data of the initial parameterization, and use a 12 km resolution soil biome map over the continental USA. CMAQ modeling for July 2011 shows slight differences in model performance in simulating fine particulate matter and ozone from Interagency Monitoring of Protected Visual Environments (IMPROVE) and Clean Air Status and Trends Network (CASTNET) sites and NO2 columns from Ozone Monitoring Instrument (OMI) satellite retrievals. We also simulate how the change in soil NO emissions scheme affects the expected O3 response to projected emissions reductions.

Highlights

Nitrogen oxides (NOx = nitric oxide (NO) + NO2) play a crucial role in tropospheric chemistry
We considered the baseline NOx reduction scenario from 2011 to 2025 that EPA’s Regulatory Impact Analysis (RIA) determined for business as usual (BAU) in the continental United States (CONUS) domain (Fig. 2A-1, Table 2A-1 in https://www3. epa.gov/ttn/ecas/docs/20151001ria.pdf)
Emissions increase by a factor ranging from 1.8 to 2.8 in shifting from YL to Berkley Dalhousie Soil NO Parameterization (BDSNP), even while retaining the Potter et al (2010) fertilizer data and original biome map, indicating that the shift from the YL to the BDSNP scheme is the largest driver of the increase in emissions estimates

Summary

Introduction

NOx affects the lifetime of reactive greenhouse gases like CH4 by influencing its dominant oxidant OH (Steinkamp and Lawrence, 2011), affecting the Earth’s radiative balance (IPCC, 2007). The estimated amount of nitric oxide (NO) emitted from soils is highly uncertain, ranging from 4 to 15 Tg N yr−1, with different estimates of total global NOx budget showing a mean difference of 60–70 % (Potter et al, 1996; Davidson and Kingerlee, 1997; Yienger and Levy, 1995; Jaeglé et al, 2005; Stavrakou et al, 2008; Steinkamp and Lawrence, 2011; Miyazaki et al, 2012; Stavrakou et al, 2013; Vinken et al, 2014). Soil NOx is mainly emitted as NO through both microbial activity (biotic/enzymatic) and chemical (abiotic/non-enzymatic) pathways, with emission rates

Methods

Results

Conclusion