The Community Multiscale Air Quality (CMAQ) model versions 5.3 and 5.3.1: system updates and evaluation

Geoscientific model development, Journal Year: 2021, Volume and Issue: 14(5), P. 2867 - 2897

Published: May 20, 2021

The Community Multiscale Air Quality (CMAQ) model version 5.3 (CMAQ53), released to the public in August 2019 and followed by 5.3.1 (CMAQ531) December 2019, contains numerous science updates, enhanced functionality, improved computation efficiency relative previous of model, 5.2.1 (CMAQ521). Major advances new include a aerosol module (AERO7) with significant updates secondary organic (SOA) chemistry, updated chlorine detailed bromine iodine simple halogen addition dimethyl sulfide (DMS) chemistry CB6r3 chemical mechanism, M3Dry bidirectional deposition Surface Tiled Aerosol Gaseous Exchange (STAGE) model. In addition, support for Weather Research Forecasting (WRF) model's hybrid vertical coordinate (HVC) was added CMAQ53 Meteorology-Chemistry Interface Processor (MCIP) 5.0 (MCIP50). Enhanced functionality includes Detailed Emissions Scaling, Isolation Diagnostic (DESID) system scaling incoming emissions CMAQ reading multiple gridded input emission files. Evaluation CMAQ531 performed comparing monthly seasonal mean daily 8 h average (MDA8) O3 PM2.5 values from several simulations similarly configured CMAQ521 simulation encompassing 2016. For MDA8 O3, has higher winter versus CMAQ521, due primarily reduced dry snow, which strongly reduces wintertime bias (2-4 ppbv average). is lower throughout rest year, particularly spring, part lateral boundary conditions (BCs), generally increases spring fall ( 0.5 μg m-3). 24 PM2.5, concentrations on fall, summer, similar slightly summer. Comparisons were also isolate specific aspects modeling system, namely BCs, meteorology version, used. Transitioning hemispheric (HCMAQ) HCMAQ provide BCs contributes mixing ratios regional latitudes during (due decreased snow CMAQ53) middle year-round over ocean CMAQ53). WRF 3.8 4.1.1 HVC resulted consistently (1.0-1.5 ppbv) (0.1-0.25 m-3) year. Finally, comparisons STAGE models showed that outside while differences assumptions particle velocities non-vegetated surfaces land use short vegetation (e.g., grasslands) between two models. ambient NH3, smaller winter, but larger error correlation

Language: Английский

---

Estimation of biogenic VOC emissions and their corresponding impact on ozone and secondary organic aerosol formation in China

Atmospheric Research, Journal Year: 2019, Volume and Issue: 231, P. 104656 - 104656

Published: Aug. 24, 2019

Language: Английский

---

The complex chemical effects of COVID-19 shutdowns on air quality

Nature Chemistry, Journal Year: 2020, Volume and Issue: 12(9), P. 777 - 779

Published: Aug. 25, 2020

Stay-at-home policies invoked in response to COVID-19 have led well-publicized drops some air pollutants. The extent which such reductions translate improved quality is dictated by not only emissions and meteorology, but also chemical transformations the atmosphere.

Language: Английский

---

Assessing NO₂ Concentration and Model Uncertainty with High Spatiotemporal Resolution across the Contiguous United States Using Ensemble Model Averaging

Environmental Science & Technology, Journal Year: 2019, Volume and Issue: 54(3), P. 1372 - 1384

Published: Dec. 18, 2019

NO2 is a combustion byproduct that has been associated with multiple adverse health outcomes. To assess levels high accuracy, we propose the use of an ensemble model to integrate machine learning algorithms, including neural network, random forest, and gradient boosting, variety predictor variables, chemical transport models. This covers entire contiguous U.S. daily predictions on 1-km-level grid cells from 2000 2016. The produced cross-validated R2 0.788 overall, spatial 0.844, temporal 0.729. relationship between monitored predicted almost linear. We also estimated monthly uncertainty level for address-specific levels. estimation very spatiotemporal resolution allows examination effects in unmonitored areas. found highest along highways cities. observed nationwide declined early years stagnated after 2007, contrast trend at monitoring sites urban areas, where decline continued. Our research indicates integration different variables fitting algorithms can achieve improved air pollution modeling framework.

Language: Английский

---

Secondary organic aerosol association with cardiorespiratory disease mortality in the United States

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: Dec. 16, 2021

Abstract Fine particle pollution, PM 2.5 , is associated with increased risk of death from cardiorespiratory diseases. A multidecadal shift in the United States (U.S.) composition towards organic aerosol as well advances predictive algorithms for secondary (SOA) allows novel examinations role components on mortality. Here we show SOA strongly county-level rates U.S. independent total mass association largest associations located southeastern Compared to variability across 3.5× greater per capita On a basis, 6.5× higher rate mortality than and biogenic anthropogenic carbon sources both play overall Our results suggest reducing health impacts requires consideration SOA.

Language: Английский

---

The fuel of atmospheric chemistry: Toward a complete description of reactive organic carbon

Science Advances, Journal Year: 2020, Volume and Issue: 6(6)

Published: Feb. 6, 2020

Tracking reactive organic carbon in the atmosphere is critical to advancing our understanding of air quality and climate.

Language: Английский

---

An evaluation of global organic aerosol schemes using airborne observations

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(5), P. 2637 - 2665

Published: March 4, 2020

Abstract. Chemical transport models have historically struggled to accurately simulate the magnitude and variability of observed organic aerosol (OA), with previous studies demonstrating that significantly underestimate concentrations in troposphere. In this study, we explore two different model OA schemes within standard GEOS-Chem chemical evaluate simulations against a suite 15 globally distributed airborne campaigns from 2008 2017, primarily spring summer seasons. These include ATom, KORUS-AQ, GoAmazon, FRAPPE, SEAC4RS, SENEX, DC3, CalNex, OP3, EUCAARI, ARCTAS ARCPAC provide broad coverage over diverse set atmospheric composition regimes – anthropogenic, biogenic, pyrogenic remote. The significant differences their treatment primary secondary components “simple scheme” (POA) as non-volatile takes fixed-yield approach (SOA) formation “complex simulates POA semi-volatile uses more sophisticated volatility basis for non-isoprene SOA, an explicit aqueous uptake mechanism isoprene SOA. Despite these substantial differences, both simple complex perform comparably across aggregate dataset ability capture (with R2 0.41 0.44, respectively). scheme displays greater skill minimizing overall bias normalized mean 0.04 compared 0.30 scheme). Across schemes, reproducing is superior evaluations approaches fidelity sulfate simulation model. However, there are performance source regimes, classified here into seven categories. Higher-resolution nested regional indicate resolution important factor capturing highly localized campaigns, while also importance well-constrained emissions inventories local meteorology, particularly Asia. Our analysis suggests treatment. It likely parameterization overestimates biogenic SOA at global scale. While study identifies factors contribute (such strong dependency on relative humidity concentrations), comparisons other drivers bias, such emissions, deposition, exogenous scheme.

Language: Английский

---

Organic Peroxides in Aerosol: Key Reactive Intermediates for Multiphase Processes in the Atmosphere

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(4), P. 1635 - 1679

Published: Jan. 11, 2023

Organic peroxides (POs) are organic molecules with one or more peroxide (−O–O−) functional groups. POs commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve temporary reservoirs for oxidative radicals (HOx ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, reactivity, key reactive intermediates atmospheric multiphase processes determining life cycle (formation, growth, aging), climate, health impacts of aerosol. However, there remain substantial gaps origin, molecular diversity, fate due complex nature dynamic behavior. Here, we summarize current understanding on POs, a focus identification quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, chemical transformation pathways, well environmental impacts. We find that interactions SO2 transition metal ions generally fast PO pathways liquid water, lifetimes estimated be minutes hours, while hydrolysis is particularly important α-substituted hydroperoxides. Meanwhile, photolysis thermolysis likely minor sinks POs. These distinctly different fates, such reaction OH radicals, which highlights need understand By summarizing advances remaining challenges investigation propose future research priorities regarding fate,

Language: Английский

---

Tropical and Boreal Forest – Atmosphere Interactions: A Review

Tellus B, Journal Year: 2022, Volume and Issue: 74(1), P. 24 - 24

Published: March 25, 2022

This review presents how the boreal and tropical forests affect atmosphere, its chemical composition, function, further that affects climate and, in return, ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory Central Amazonia, Zotino Siberia, Station Measure Ecosystem-Atmosphere Relations at Hyytiäla Finland. is complemented by short-term observations networks large experiments. discusses atmospheric chemistry observations, aerosol formation processing, physiochemical aerosol, cloud condensation nuclei properties finds surprising similarities important differences two ecosystems. concentrations are similar, particularly concerning main components, both dominated an organic fraction, while ecosystem has generally higher of inorganics, influence long-range transported air pollution. emissions biogenic volatile compounds isoprene monoterpene regions, respectively, being precursors fraction. modeling studies show change deforestation such carbon hydrological cycles Amazonia changing neutrality precipitation downwind. In Africa, so far maintaining sink. It urgent better understand interaction between these major ecosystems, climate, which calls for more observation sites, providing data on water, carbon, other biogeochemical cycles. essential finding a sustainable balance forest preservation reforestation versus potential increase food production biofuels, critical services global stability. Reducing warming vital forests.

Language: Английский

---

Chemical composition and hydrolysis of organic nitrate aerosol formed from hydroxyl and nitrate radical oxidation of α-pinene and β-pinene

Atmospheric chemistry and physics, Journal Year: 2019, Volume and Issue: 19(19), P. 12749 - 12766

Published: Oct. 11, 2019

Abstract. Atmospheric organic nitrate (ON) is thought to play a crucial role in the formation potential of ozone and aerosol, which are leading air pollutants concern across world. Limited fundamental knowledge understanding life cycles ON currently hinder ability quantitatively assess its impacts on these pollutants. Although hydrolysis considered an important loss mechanism based prior field measurement studies, this process for atmospherically relevant has not been well constrained by laboratory studies. In comprehensive study, we investigated chemical composition particulate (pON) formed from oxidation α-pinene β-pinene hydroxyl (OH⚫) radicals (NO3⚫). For pON that undergoes hydrolysis, lifetime determined be no more than 30 min all systems explored. This significantly shorter those reported previous chamber studies (i.e., 3–6 h) but consistent with bulk solution 0.02–8.8 h). The discrepancy appears stem choice proxy used estimate lifetime. measured hydrolyzable fractions (FH) + OH⚫, NO3⚫, NO3⚫ 23 %–32 %, 27 %–34 9 %–17 %–15 respectively. While very low FH system expected OH⚫ surprisingly lower predicted past Overall, as obtained study serve experimentally parameters required regional global transport models accurately evaluate nitrogen budget aerosol.

Language: Английский

---