scholarly journals Quantifying sources of black carbon in Western North America using observationally based analysis and an emission tagging technique in the Community Atmosphere Model

2015 ◽  
Vol 15 (9) ◽  
pp. 12957-13000
Author(s):  
R. Zhang ◽  
H. Wang ◽  
D. A. Hegg ◽  
Y. Qian ◽  
S. J. Doherty ◽  
...  
Keyword(s):  
North America ◽  
Black Carbon ◽  
Local Source ◽  
Western North America ◽  
Near Surface ◽  
Mixing Ratios ◽  
Source Regions ◽  
Source Type ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. The Community Atmosphere Model (CAM5), equipped with a technique to tag black carbon (BC) emissions by source regions and types, has been employed to establish source-receptor relationships for atmospheric BC and its deposition to snow over Western North America. The CAM5 simulation was conducted with meteorological fields constrained by reanalysis for year 2013 when measurements of BC in both near-surface air and snow are available for model evaluation. We find that CAM5 has a significant low bias in predicted mixing ratios of BC in snow but only a small low bias in predicted atmospheric concentrations over the Northwest USA and West Canada. Even with a strong low bias in snow mixing ratios, radiative transfer calculations show that the BC-in-snow darkening effect is substantially larger than the BC dimming effect at the surface by atmospheric BC. Local sources contribute more to near-surface atmospheric BC and to deposition than distant sources, while the latter are more important in the middle and upper troposphere where wet removal is relatively weak. Fossil fuel (FF) is the dominant source type for total column BC burden over the two regions. FF is also the dominant local source type for BC column burden, deposition, and near-surface BC, while for all distant source regions combined the contribution of biomass/biofuel (BB) is larger than FF. An observationally based Positive Matrix Factorization (PMF) analysis of the snow-impurity chemistry is conducted to quantitatively evaluate the CAM5 BC source-type attribution. While CAM5 is qualitatively consistent with the PMF analysis with respect to partitioning of BC originating from BB and FF emissions, it significantly underestimates the relative contribution of BB. In addition to a possible low bias in BB emissions used in the simulation, the model is likely missing a significant source of snow darkening from local soil found in the observations.

scholarly journals Quantifying sources of black carbon in western North America using observationally based analysis and an emission tagging technique in the Community Atmosphere Model

2015 ◽  
Vol 15 (22) ◽  
pp. 12805-12822 ◽  
Author(s):  
R. Zhang ◽  
H. Wang ◽  
D. A. Hegg ◽  
Y. Qian ◽  
S. J. Doherty ◽  
...  
Keyword(s):  
North America ◽  
Black Carbon ◽  
Local Source ◽  
Western North America ◽  
Near Surface ◽  
Mixing Ratios ◽  
Source Regions ◽  
Source Type ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. The Community Atmosphere Model (CAM5), equipped with a technique to tag black carbon (BC) emissions by source regions and types, has been employed to establish source–receptor relationships for atmospheric BC and its deposition to snow over western North America. The CAM5 simulation was conducted with meteorological fields constrained by reanalysis for year 2013 when measurements of BC in both near-surface air and snow are available for model evaluation. We find that CAM5 has a significant low bias in predicted mixing ratios of BC in snow but only a small low bias in predicted atmospheric concentrations over northwestern USA and western Canada. Even with a strong low bias in snow mixing ratios, radiative transfer calculations show that the BC-in-snow darkening effect is substantially larger than the BC dimming effect at the surface by atmospheric BC. Local sources contribute more to near-surface atmospheric BC and to deposition than distant sources, while the latter are more important in the middle and upper troposphere where wet removal is relatively weak. Fossil fuel (FF) is the dominant source type for total column BC burden over the two regions. FF is also the dominant local source type for BC column burden, deposition, and near-surface BC, while for all distant source regions combined the contribution of biomass/biofuel (BB) is larger than FF. An observationally based positive matrix factorization (PMF) analysis of the snow-impurity chemistry is conducted to quantitatively evaluate the CAM5 BC source-type attribution. While CAM5 is qualitatively consistent with the PMF analysis with respect to partitioning of BC originating from BB and FF emissions, it significantly underestimates the relative contribution of BB. In addition to a possible low bias in BB emissions used in the simulation, the model is likely missing a significant source of snow darkening from local soil found in the observations.

scholarly journals Revisiting the evidence of increasing springtime ozone mixing ratios in the free troposphere over western North America

2015 ◽  
Vol 42 (20) ◽  
pp. 8719-8728 ◽  
Author(s):  
Meiyun Lin ◽  
Larry W. Horowitz ◽  
Owen R. Cooper ◽  
David Tarasick ◽  
Stephen Conley ◽  
...  
Keyword(s):  
North America ◽  
Free Troposphere ◽  
Western North America ◽  
Mixing Ratios

High-Frequency Seismic Wave Propagation in Northeastern North America

1990 ◽  
Vol 61 (3-4) ◽  
pp. 193-208 ◽  
Author(s):  
S. E. Hough ◽  
K. H. Jacob ◽  
L. Seeber
Keyword(s):  
North America ◽  
High Frequency ◽  
Characteristic Length ◽  
Body Waves ◽  
Eastern North America ◽  
Western North America ◽  
Energy Propagation ◽  
Length Scales ◽  
Near Surface ◽  
High Frequencies

Abstract A key element in the assessment of seismic hazard is the estimation of how energy propagation from a given earthquake is affected by crustal structure near the receiver and along the more distant propagation path. In this paper, we present data from a variety of sources in eastern North America recorded at epicentral distances of a few to 800 km, and characterize and interpret systematic features. Site effects have been classically considered in terms of amplification either within a sediment-filled valley or from a single topographic feature (Geli et al., 1988). We present evidence of high frequency (5–30 Hz) resonances observed in hard-rock recordings of both body waves and Lg waves, and suggest that site effect should be expanded regionally to include structural and topographic information over sufficiently large areas to include several wavelengths of any features that may interact with seismic waves in the frequency range of interest. A growing body of evidence suggests that ground motions at high frequencies recorded at large epicentral distances in eastern North America are controlled by resonance effects. We hypothesize that a fundamental difference between eastern and western North America spectra stems from a combination of differences in the character of topography and near-surface structure. Active tectonics of western North America gives rise to a complex crust that scatters seismic energy in a random manner and results in very effective attenuation of high frequencies. The older eastern North American crust contains scatterers that are more ordered, with characteristic length scales that give rise to resonance phenomena in the frequency band critical for earthquake hazard. We present preliminary analysis of topographic data from the Adirondack Mountains in New York that demonstrates the existence of characteristic length scales on the order of up to 1–3 kilometers. Features with these length scales will effectively scatter energy at frequencies in the 1 to 10 Hz range.

The role of circulation features on black carbon transport into the Arctic in the Community Atmosphere Model version 5 (CAM5)

2013 ◽  
Vol 118 (10) ◽  
pp. 4657-4669 ◽  
Author(s):  
Po-Lun Ma ◽  
Philip J. Rasch ◽  
Hailong Wang ◽  
Kai Zhang ◽  
Richard C. Easter ◽  
...  
Keyword(s):  
Black Carbon ◽  
The Arctic ◽  
Model Version ◽  
Community Atmosphere Model ◽  
Atmosphere Model ◽  
Carbon Transport

scholarly journals Temperature Extremes in the Community Atmosphere Model with Stochastic Parameterizations*

2015 ◽  
Vol 29 (1) ◽  
pp. 241-258 ◽  
Author(s):  
Felipe Tagle ◽  
Judith Berner ◽  
Mircea D. Grigoriu ◽  
Natalie M. Mahowald ◽  
Gennady Samorodnitsky
Keyword(s):  
Global Climate ◽  
Climate Extremes ◽  
Temperature Extremes ◽  
Systematic Bias ◽  
Near Surface ◽  
Community Atmosphere Model ◽  
Atmosphere Model ◽  
Hadley Centre ◽  
The Impact ◽  
Cold Extremes

AbstractThis paper evaluates the performance of the NCAR Community Atmosphere Model, version 4 (CAM4), in simulating observed annual extremes of near-surface temperature and provides the first assessment of the impact of stochastic parameterizations of subgrid-scale processes on such performance. Two stochastic parameterizations are examined: the stochastic kinetic energy backscatter scheme and the stochastically perturbed parameterization tendency scheme. Temperature extremes are described in terms of 20-yr return levels and compared to those estimated from ERA-Interim and the Hadley Centre Global Climate Extremes Index 2 (HadEX2) observational dataset. CAM4 overestimates warm and cold extremes over land regions, particularly over the Northern Hemisphere, when compared against reanalysis. Similar spatial patterns, though less spatially coherent, emerge relative to HadEX2. The addition of a stochastic parameterization generally produces a warming of both warm and cold extremes relative to the unperturbed configuration; however, neither of the proposed parameterizations meaningfully reduces the biases in the simulated temperature extremes of CAM4. Adjusting warm and cold extremes by mean conditions in the respective annual extremes leads to good agreement between the models and reanalysis; however, adjusting for the bias in mean temperature does not help to reduce the observed discrepancies. Based on the behavior of the annual extremes, this study concludes that the distribution of temperature in CAM4 exhibits too much variability relative to that of reanalysis, while the stochastic parameterizations introduce a systematic bias in its mean rather than alter its variability.

scholarly journals Responses of Arctic black carbon and surface temperature to multi-region emission reductions: a Hemispheric Transport of Air Pollution Phase 2 (HTAP2) ensemble modeling study

2021 ◽  
Vol 21 (11) ◽  
pp. 8637-8654
Author(s):  
Na Zhao ◽  
Xinyi Dong ◽  
Kan Huang ◽  
Joshua S. Fu ◽  
Marianne Tronstad Lund ◽  
...  
Keyword(s):  
Air Pollution ◽  
Surface Temperature ◽  
Black Carbon ◽  
The Arctic ◽  
Ensemble Modeling ◽  
Phase 2 ◽  
Emission Reductions ◽  
Near Surface ◽  
Source Regions ◽  
The Impact

Abstract. Black carbon (BC) emissions play an important role in regional climate change in the Arctic. It is necessary to pay attention to the impact of long-range transport from regions outside the Arctic as BC emissions from local sources in the Arctic were relatively small. The task force Hemispheric Transport of Air Pollution Phase 2 (HTAP2) set up a series of simulation scenarios to investigate the response of BC in a given region to different source regions. This study investigated the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from six regions in 2010 within the framework of HTAP2 based on ensemble modeling results. Emission reductions from East Asia (EAS) had the most (monthly contributions: 0.2–1.5 ng m−3) significant impact on the Arctic near-surface BC concentrations, while the monthly contributions from Europe (EUR), Middle East (MDE), North America (NAM), Russia–Belarus–Ukraine (RBU), and South Asia (SAS) were 0.2–1.0, 0.001–0.01, 0.1–0.3, 0.1–0.7, and 0.0–0.2 ng m−3, respectively. The responses of the vertical profiles of the Arctic BC to the six regions were found to be different due to multiple transport pathways. Emission reductions from NAM, RBU, EUR, and EAS mainly influenced the BC concentrations in the low troposphere of the Arctic, while most of the BC in the upper troposphere of the Arctic derived from SAS. The response of the Arctic BC to emission reductions in six source regions became less significant with the increase in the latitude. The benefit of BC emission reductions in terms of slowing down surface warming in the Arctic was evaluated by using absolute regional temperature change potential (ARTP). Compared to the response of global temperature to BC emission reductions, the response of Arctic temperature was substantially more sensitive, highlighting the need for curbing global BC emissions.

scholarly journals Source attribution of black carbon and its direct radiative forcing in China

2016 ◽  
Author(s):  
Yang Yang ◽  
Hailong Wang ◽  
Steven J. Smith ◽  
Po-Lun Ma ◽  
Philip J. Rasch
Keyword(s):  
Air Quality ◽  
East Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
North China ◽  
Local Source ◽  
Near Surface ◽  
Direct Radiative Forcing ◽  
Non Local ◽  
Local Emissions

Abstract. The source attributions for mass concentration, haze formation, transport, and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over North China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. 30 % of BC concentration over South China in winter can be attributed to emissions from North China and 10 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from non-local sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from non-local source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 7 % of BC concentration and 25 % in column burden in western United States in spring. Radiative forcing estimated shows that 66 % of the annual mean BC direct radiative forcing (2.3 W m−2) in China results from local emissions, and the remaining 34 % are contributed by emissions outside of China. Efficiency analysis shows that reduction in BC emissions over eastern China could benefit more on the regional air quality in China, especially in winter haze season.

scholarly journals Trends and source apportionment of aerosols in Europe during 1980–2018

2019 ◽  
Author(s):  
Yang Yang ◽  
Sijia Lou ◽  
Hailong Wang ◽  
Pinya Wang ◽  
Hong Liao
Keyword(s):  
Radiative Forcing ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Comparable Rate ◽  
Near Surface ◽  
Source Regions ◽  
Community Atmosphere Model ◽  
Radiative Impact ◽  
Local Emissions ◽  
Aerosol Source

Abstract. Aerosols have significantly affected health, environment and climate in Europe. Aerosol concentrations have been declining since 1980s in Europe, mainly owing to the reduction of local aerosol and precursor emissions. Emissions from other source regions of the world, which have been changing rapidly as well, may also perturb the historical and future trends of aerosols and change their radiative impact in Europe. This study examines trends of aerosols in Europe during 1980–2018 and quantify contributions from sixteen source regions using the Community Atmosphere Model version 5 with an Explicit Aerosol Source Tagging technique (CAM5-EAST). The simulated near-surface total mass concentration of sulfate, black carbon and primary organic carbon had a 62 % decrease during 1980–2018, of which the majority was contributed by reductions of local emissions in Europe and 8 %–9 % was induced by the decrease in emissions from Russia–Belarus–Ukraine. With the decreases in the fractional contribution of local emissions, aerosols transported from other source regions are increasingly important to air quality in Europe. During 1980–2018, the decrease in sulfate loading leads to a warming effect of 2.0 W m−2 in Europe, with 12 % coming from changes in non-European sources, especially from North America and Russia–Belarus–Ukraine. According to the Shared Socioeconomic Pathways (SSP) scenarios, contributions to the sulfate radiative forcing over Europe from both European local emissions and non-European emissions would decrease at a comparable rate in the next three decades, suggesting that future changes in non-European emissions are as important as European emissions in causing possible regional climate change associated with aerosols in Europe.

scholarly journals Increasing springtime ozone mixing ratios in the free troposphere over western North America

Nature ◽  
2010 ◽  
Vol 463 (7279) ◽  
pp. 344-348 ◽  
Author(s):  
O. R. Cooper ◽  
D. D. Parrish ◽  
A. Stohl ◽  
M. Trainer ◽  
P. Nédélec ◽  
...  
Keyword(s):  
North America ◽  
Free Troposphere ◽  
Western North America ◽  
Mixing Ratios
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