Assessment of the MACC reanalysis and its influence as chemical boundary conditions for regional air quality modeling in AQMEII-2

Abstract

?? 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)The Air Quality Model Evaluation International Initiative (AQMEII) has now reached its second phase which is dedicated to the evaluation of online coupled chemistry-meteorology models. Sixteen modelling groups from Europe and five from North America have run regional air quality models to simulate the year 2010 over one European and one North American domain. The MACC re-analysis has been used as chemical initial (IC) and boundary conditions (BC) by all participating regional models in AQMEII-2. The aim of the present work is to evaluate the MACC re-analysis along with the participating regional models against a set of ground-based measurements (O3, CO, NO, NO2, SO2, SO42-) and vertical profiles (O3 and CO). Results indicate different degrees of agreement between the measurements and the MACC re-analysis, with an overall better performance over the North American domain. The influence of BC on regional air quality simulations is analyzed in a qualitative way by contrasting model performance for the MACC re-analysis with that for the regional models. This approach complements more quantitative approaches documented in the literature that often have involved sensitivity simulations but typically were limited to only one or only a few regional scale models. Results suggest an important influence of the BC on ozone for which the underestimation in winter in the MACC re-analysis is mimicked by the regional models. For CO, it is found that background concentrations near the domain boundaries are rather close to observations while those over the interior of the two continents are underpredicted by both MACC and the regional models over Europe but only by MACC over North America. This indicates that emission differences between the MACC re-analysis and the regional models can have a profound impact on model performance and points to the need for harmonization of inputs in future linked global/regional modeling studies

Low modeled ozone production suggests underestimation of precursor emissions (especially NO<sub><i>x</i></sub>) in Europe

“…However, the accurate modeling of CO is a common problem in the European modeling community and our results are similar to other studies (Nopmongcol et al, 2012;Solazzo et al, 2013Solazzo et al, , 2017Giordano et al, 2015). Since CO concentrations do not change rapidly by chemistry and deposition processes, the differences between model and observations are mostly related to boundary conditions, vertical mixing and emissions (Solazzo et al, 2013(Solazzo et al, , 2017Giordano et al, 2015). Although the bias for NO 2 is small (−0.2 ppb), the MGE and RMSE are much higher (in absolute terms), indicating compensation between over-and underestimation throughout the day leading to a weak correlation coefficient (0.4).…”

“…The overall model performance for the daily mean concentrations of the air pollutants in summer (JJA) 2010 (Table 5) was reasonably good. The statistical evaluation results for most chemical species were in line with those reported for various models and parameterizations for summer periods in Europe (Bessagnet et al, 2004Solazzo et al, 2012a, b;Nopmongcol et al, 2012;Giordano et al, 2015). Model performance goals and criteria for O 3 and PM 2.5 (Table 2), recommended by Boylan and Russell (2006) and EPA (2007), were met.…”

“…Many studies (Katragkou et al, 2010;Solazzo et al, 2013;Giordano et al, 2015;Im et al, 2015) have reported a strong influence of the boundary conditions on ozone mixing ratios, but their impact is less significant near the surface and inside the PBL, as well as in summer compared to other seasons (winter or autumn), due to more dominant near-surface effects (e.g., photochemistry, emissions, transport, dry deposition). Furthermore, Katragkou et al (2010) showed that the impact of increased O 3 in the lateral boundaries by 8 ppb in Europe in summer was already down to half (3-4 ppb) over Great Britain and western Scandinavia and faded out towards central and southeast Europe.…”

A comparison between 2010 and 2006 air quality and meteorological conditions, and emissions and boundary conditions used in simulations of the AQMEII-2 North American domain

“…Boundary conditions (BCs) can have a significant impact on regional model predictions (Schere et al, 2012) towards changed BC for January and July 2006 while Giordano et al (2015) compare pollutant concentrations simulated by IFS-MOZART and the AQMEII-2 regional models for 2010 to estimate the degree to which BC affect regional simulations. In this study, we complement their analyses by presenting comparisons of IFS-MOZART seasonal mean mid-tropospheric predictions over North America to gain some insight into the likely influence of large-scale background changes between 2006 and 2010 on the regional model predictions based on the assumption that mid-tropospheric conditions are roughly indicative of impacts of BC tendencies on concentrations at the surface.…”

Contributions of natural and anthropogenic sources to ambient ammonia in the Athabasca Oil Sands and north-western Canada

“…In a previous study by , it was found that the GEM-MACH air quality forecasting model (Moran et al, 2010;Moran et al, 2013;Makar et al, 2015a, b;Gong et al, 2015), using a domain covering the Canadian provinces of Alberta and Saskatchewan at 2.5 km resolution, under-predicted summertime tropospheric ammonia VMRs by 0.4-0.6 ppbv (which is 36-100 % depending on altitude -see Fig. 16 in in the AOSR when compared to the Tropospheric Emission Spectrometer (TES) satellite measurements and aircraft measurements.…”