scholarly journals Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry

2012 ◽  
Vol 12 (2) ◽  
pp. 6049-6084 ◽  
Author(s):  
J. P. DiGangi ◽  
S. B. Henry ◽  
A. Kammrath ◽  
E. S. Boyle ◽  
L. Kaser ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Pinus Ponderosa ◽  
Model Comparison ◽  
Organic Aerosol ◽  
In Situ Measurements ◽  
Rapid Changes ◽  
Volatile Organic ◽  
Satellite Retrievals ◽  
Voc Mixtures

Abstract. We present simultaneous fast, in-situ measurements of formaldehyde and glyoxal from two rural campaigns, BEARPEX 2009 and BEACHON-ROCS, both located in Pinus Ponderosa forests with emissions dominated by biogenic volatile organic compounds (VOCs). Despite considerable variability in the formaldehyde and glyoxal concentrations, the ratio of glyoxal to formaldehyde, RGF, displayed a very regular diurnal cycle over nearly 2 weeks of measurements. The only deviations in RGF were toward higher values and were the result of a biomass burning event during BEARPEX 2009 and very fresh anthropogenic influence during BEACHON-ROCS. Other rapid changes in glyoxal and formaldehyde concentrations have hardly any affect on RGF and could reflect transitions between low and high NO regimes. The trend of increased RGF from both anthropogenic reactive VOC mixtures and biomass burning compared to biogenic reactive VOC mixtures is robust due to the short timescales over which the observed changes in RGF occurred. Satellite retrievals, which suggest higher RGF for biogenic areas, are in contrast to our observed trends. It remains important to address this discrepancy, especially in view of the importance of satellite retrievals and in-situ measurements for model comparison. In addition, we propose that RGF, together with the absolute concentrations of glyoxal and formaldehyde, represents a useful metric for biogenic or anthropogenic reactive VOC mixtures. In particular, RGF yields information about not simply the VOCs in an airmass, but the VOC processing that directly couples ozone and secondary organic aerosol production.

scholarly journals Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry

2012 ◽  
Vol 12 (20) ◽  
pp. 9529-9543 ◽  
Author(s):  
J. P. DiGangi ◽  
S. B. Henry ◽  
A. Kammrath ◽  
E. S. Boyle ◽  
L. Kaser ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Pinus Ponderosa ◽  
Model Comparison ◽  
In Situ Measurements ◽  
Anthropogenic Influence ◽  
Rapid Changes ◽  
Volatile Organic ◽  
Satellite Retrievals ◽  
Voc Mixtures

Abstract. We present simultaneous fast, in-situ measurements of formaldehyde and glyoxal from two rural campaigns, BEARPEX 2009 and BEACHON-ROCS, both located in Pinus Ponderosa forests with emissions dominated by biogenic volatile organic compounds (VOCs). Despite considerable variability in the formaldehyde and glyoxal concentrations, the ratio of glyoxal to formaldehyde, RGF, displayed a very regular diurnal cycle over nearly 2 weeks of measurements. The only deviations in RGF were toward higher values and were the result of a biomass burning event during BEARPEX 2009 and very fresh anthropogenic influence during BEACHON-ROCS. Other rapid changes in glyoxal and formaldehyde concentrations have hardly any affect on RGF and could reflect transitions between low and high NO regimes. The trend of increased RGF from both anthropogenic reactive VOC mixtures and biomass burning compared to biogenic reactive VOC mixtures is robust due to the short timescales over which the observed changes in RGF occurred. Satellite retrievals, which suggest higher RGF for biogenic areas, are in contrast to our observed trends. It remains important to address this discrepancy, especially in view of the importance of satellite retrievals and in situ measurements for model comparison. In addition, we propose that RGF represents a useful metric for biogenic or anthropogenic reactive VOC mixtures and, in combination with absolute concentrations of glyoxal and formaldehyde, furthermore represents a useful metric for the extent of anthropogenic influence on overall reactive VOC processing via NOx. In particular, RGF yields information about not simply the VOCs dominating reactivity in an airmass, but the VOC processing itself that is directly coupled to ozone and secondary organic aerosol production.

scholarly journals Wildfire Smoke Particle Properties and Evolution, From Space-Based Multi-Angle Imaging II: The Williams Flats Fire during the FIREX-AQ Campaign

2020 ◽  
Vol 12 (22) ◽  
pp. 3823
Author(s):  
Katherine T. Junghenn Noyes ◽  
Ralph A. Kahn ◽  
James A. Limbacher ◽  
Zhanqing Li ◽  
Marta A. Fenn ◽  
...  
Keyword(s):  
Particle Size ◽  
Biomass Burning ◽  
In Situ Measurements ◽  
Statistical Characterization ◽  
Smoke Particle ◽  
Particle Properties ◽  
In Situ Data ◽  
Particle Property ◽  
Aircraft Data

Although the characteristics of biomass burning events and the ambient ecosystem determine emitted smoke composition, the conditions that modulate the partitioning of black carbon (BC) and brown carbon (BrC) formation are not well understood, nor are the spatial or temporal frequency of factors driving smoke particle evolution, such as hydration, coagulation, and oxidation, all of which impact smoke radiative forcing. In situ data from surface observation sites and aircraft field campaigns offer deep insight into the optical, chemical, and microphysical traits of biomass burning (BB) smoke aerosols, such as single scattering albedo (SSA) and size distribution, but cannot by themselves provide robust statistical characterization of both emitted and evolved particles. Data from the NASA Earth Observing System’s Multi-Angle Imaging SpectroRadiometer (MISR) instrument can provide at least a partial picture of BB particle properties and their evolution downwind, once properly validated. Here we use in situ data from the joint NOAA/NASA 2019 Fire Influence on Regional to Global Environments Experiment-Air Quality (FIREX-AQ) field campaign to assess the strengths and limitations of MISR-derived constraints on particle size, shape, light-absorption, and its spectral slope, as well as plume height and associated wind vectors. Based on the satellite observations, we also offer inferences about aging mechanisms effecting downwind particle evolution, such as gravitational settling, oxidation, secondary particle formation, and the combination of particle aggregation and condensational growth. This work builds upon our previous study, adding confidence to our interpretation of the remote-sensing data based on an expanded suite of in situ measurements for validation. The satellite and in situ measurements offer similar characterizations of particle property evolution as a function of smoke age for the 06 August Williams Flats Fire, and most of the key differences in particle size and absorption can be attributed to differences in sampling and changes in the plume geometry between sampling times. Whereas the aircraft data provide validation for the MISR retrievals, the satellite data offer a spatially continuous mapping of particle properties over the plume, which helps identify trends in particle property downwind evolution that are ambiguous in the sparsely sampled aircraft transects. The MISR data record is more than two decades long, offering future opportunities to study regional wildfire plume behavior statistically, where aircraft data are limited or entirely lacking.

scholarly journals Aerosol classification by airborne high spectral resolution lidar observations

2013 ◽  
Vol 13 (5) ◽  
pp. 2487-2505 ◽  
Author(s):  
S. Groß ◽  
M. Esselborn ◽  
B. Weinzierl ◽  
M. Wirth ◽  
A. Fix ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Spectral Resolution ◽  
Classification Scheme ◽  
In Situ Measurements ◽  
High Spectral Resolution ◽  
Data Set ◽  
Aerosol Classification ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types

Abstract. During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures – Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning mixture, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was supported by backward trajectory analysis and validated with in-situ measurements. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

scholarly journals Remote sensed and in situ constraints on processes affecting tropical tropospheric ozone

2007 ◽  
Vol 7 (3) ◽  
pp. 815-838 ◽  
Author(s):  
B. Sauvage ◽  
R. V. Martin ◽  
A. van Donkelaar ◽  
X. Liu ◽  
K. Chance ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tropospheric Ozone ◽  
In Situ Measurements ◽  
Model Bias ◽  
Top Down ◽  
Upper Troposphere ◽  
In Situ Observations ◽  
Tropospheric O3 ◽  
Bias Versus

Abstract. We use a global chemical transport model (GEOS-Chem) to evaluate the consistency of satellite measurements of lightning flashes and ozone precursors with in situ measurements of tropical tropospheric ozone. The measurements are tropospheric O3, NO2, and HCHO columns from the GOME satellite instrument, lightning flashes from the OTD and LIS satellite instruments, profiles of O3, CO, and relative humidity from the MOZAIC aircraft program, and profiles of O3 from the SHADOZ ozonesonde network. We interpret these multiple data sources with our model to better understand what controls tropical tropospheric ozone. Tropical tropospheric ozone is mainly affected by lightning NOx and convection in the upper troposphere and by surface emissions in the lower troposphere. Scaling the spatial distribution of lightning in the model to the observed flashes improves the simulation of O3 in the upper troposphere by 5–20 ppbv versus in situ observations and by 1–4 Dobson Units versus GOME retrievals of tropospheric O3 columns. A lightning source strength of 6±2 Tg N/yr best represents in situ observations from aircraft and ozonesonde. Tropospheric NO2 and HCHO columns from GOME are applied to provide top-down constraints on emission inventories of NOx (biomass burning and soils) and VOCs (biomass burning). The top-down biomass burning inventory is larger than the bottom-up inventory by a factor of 2 for HCHO and alkenes, and by a factor of 2.6 for NOx over northern equatorial Africa. These emissions increase lower tropospheric O3 by 5–20 ppbv, improving the simulation versus aircraft observations, and by 4 Dobson Units versus GOME observations of tropospheric O3 columns. Emission factors in the a posteriori inventory are more consistent with a recent compilation from in situ measurements. The ozone simulation using two different dynamical schemes (GEOS-3 and GEOS-4) is evaluated versus observations; GEOS-4 better represents O3 observations by 5–15 ppbv, reflecting enhanced convective detrainment in the upper troposphere. Heterogeneous uptake of HNO3 on aerosols reduces simulated O3 by 5–7 ppbv, reducing a model bias versus in situ observations over and downwind of deserts. Exclusion of HO2 uptake on aerosols increases O3 by 5 ppbv in biomass burning regions, reducing a model bias versus MOZAIC aircraft measurements.

scholarly journals Multiscale observations of NH3 around Toronto, Canada

2020 ◽  
Author(s):  
Shoma Yamanouchi ◽  
Camille Viatte ◽  
Kimberly Strong ◽  
Dylan B. A. Jones ◽  
Cathy Clerbaux ◽  
...  
Keyword(s):  
Case Studies ◽  
Biomass Burning ◽  
Grid Point ◽  
Fine Particulate Matter ◽  
Regional Scale ◽  
Model Performance ◽  
In Situ Measurements ◽  
Coefficient Of Determination ◽  
Predictive Capacity

<div> <div> <div> <p>Ammonia (NH<sub>3</sub>) is a major source of nitrates in the atmosphere, and a major source of fine particulate matter. As such, there have been increasing efforts to monitor NH<sub>3</sub>. This study examines long-term measurements of NH<sub>3</sub> around Toronto, Canada, derived from three multiscale datasets: 16 years of total column measurements using ground-based Fourier transform infrared (FTIR) spectroscopy, three years of surface in-situ measurements, and ten years of total columns from the Infrared Atmospheric Sounding Interferometer (IASI) sensor onboard the Metop satellites. These datasets were used to quantify NH<sub>3</sub> temporal variabilities (trends, inter-annual, seasonal) over Toronto to assess the observational footprint of the FTIR measurements, and two case studies of pollution events due to transport of biomass burning plumes.</p> <p>All three timeseries showed increasing trends in NH<sub>3</sub> over Toronto: 3.34 ± 0.44 %/year from 2002 to 2018 in the FTIR columns, 8.88 ± 2.49 %/year from 2013 to 2017 in the surface in-situ data, and 8.78 ± 0.84 %/year from 2008 to 2018 in the IASI columns. To assess the observational footprint of the FTIR NH<sub>3</sub> columns, correlations between the datasets were examined. The best correlation between FTIR and IASI was found for coincidence criterion of ≤ 50 km and ≤ 20 minutes, with r = 0.66 and a slope of 0.988 ± 0.058. The FTIR column and in-situ measurements were standardized and correlated, with 24-day averages and monthly averages yielding correlation coefficients of r = 0.72 and r = 0.75, respectively.<br>FTIR and IASI were also compared against the GEOS-Chem model, run at 2° by 2.5° resolution, to assess model performance and investigate correlation of the model output with local column measurements (FTIR) and measurements on a regional scale (IASI). Comparisons on a regional scale (domain spanning from 35°N to 53°N, and 93.75°W to 63.75°W) resulted in r = 0.62, and thus a coefficient of determination, which is indicative of the predictive capacity of the model, of r<sup>2</sup> = 0.38, but comparing a single model grid point against the FTIR resulted in a poorer correlation, with r<sup>2</sup> = 0.26, indicating that a finer spatial resolution is needed to adequately model the variability of NH<sub>3</sub>. This study also examines two case studies of NH<sub>3</sub> enhancements due to biomass burning plumes, in August 2014 and May 2016. In these events, enhancements in both the total columns and surface NH3, were observed.</p> </div> </div> </div>

scholarly journals Validation of MODIS cloud microphysical properties with in situ measurements over the Southeast Pacific

2012 ◽  
Vol 12 (1) ◽  
pp. 1419-1449 ◽  
Author(s):  
Q. Min ◽  
E. Joseph ◽  
Y. Lin ◽  
L. Min ◽  
B. Yin ◽  
...  
Keyword(s):  
Number Concentration ◽  
Effective Radius ◽  
In Situ Measurements ◽  
Liquid Water Path ◽  
Cloud Drop ◽  
Microphysical Properties ◽  
Satellite Retrievals ◽  
Drop Number ◽  
Cloud Liquid Water Path

Abstract. Utilizing the unique characteristics of the cloud over the Southeast Pacific (SEP) off the coast of Chile during the VOCALS field campaign, we validated satellite remote sensing of cloud microphysical properties against in situ data from multi-aircraft observations, and studied the extent to which these retrieved properties are sufficiently constrained and consistent to reliably quantify the influence of aerosol loading on cloud droplet sizes. After constraining the spatial-temporal coincidence between satellite retrievals and in situ measurements, we selected 17 non-drizzle comparison pairs. For these cases the mean aircraft profiling times were within one hour of Terra overpass at both projected and un-projected (actual) aircraft positions for two different averaging domains of 5 km and 25 km. Retrieved quantities that were averaged over a larger domain of 25 km compared better statistically with in situ observations than averages over a smaller domain of 5 km. Validation at projected aircraft positions was slightly better than un-projected aircraft positions for some parameters. Overall, both MODIS-retrieved effective radius and LWP were larger but highly correlated with the in situ measured effective radius and LWP. The observed effective radius difference between the two decreased with increasing cloud drop number concentration, and increased with increasing cloud geometrical thickness. Also, MODIS retrievals for adiabatic clouds agreed better with the in situ measurements than for sub-adiabatic clouds. Our validation and sensitivity analysis of simulated retrievals demonstrate that both cloud geometrical thickness and cloud adiabaticity are important factors in satellite retrievals of effective radius and cloud drop number concentration. The large variabilities in cloud geometric thickness and adiabaticity, the dependencies of cloud microphysical properties on both quantities (as demonstrated in our sensitivity study of simulated retrievals), and the inability to accurately account for either of them in retrievals lead to substantial uncertainties and biases in satellite retrieved cloud effective radius, cloud liquid water path, and cloud drop number concentration. However, strong correlations between satellite retrievals and in situ measurements suggest that satellite retrievals of cloud effective radius, cloud liquid water path, and cloud drop number concentration can be used to investigate aerosol indirect effects qualitatively.

scholarly journals Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds

2016 ◽  
Author(s):  
Wing Y. Tuet ◽  
Yunle Chen ◽  
Lu Xu ◽  
Shierly Fok ◽  
Dong Gao ◽  
...  
Keyword(s):  
Health Effects ◽  
Biomass Burning ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Hydrocarbon Emissions ◽  
Reaction Conditions ◽  
Oxidative Potential ◽  
Incomplete Combustion ◽  
Volatile Organic ◽  
Biomass Burning Aerosol

Abstract. Particulate matter (PM), of which a significant fraction is comprised of secondary organic aerosols (SOA), has received considerable attention due to their health implications. In this study, the water-soluble oxidative potential (OPWS) of SOA generated from the photooxidation of biogenic and anthropogenic hydrocarbon precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different reaction conditions (RO2 + HO2/RO2 + NO dominant, dry/humid) was characterized using dithiothreitol (DTT) consumption. The measured intrinsic OPWS-DTT ranged from 9–205 pmol min−1 µg−1 and were highly dependent on the specific hydrocarbon precursor, with naphthalene and isoprene SOA generating the highest and lowest OPWS-DTT, respectively. Humidity and RO2 fate affected OPWS-DTT in a hydrocarbon-specific manner, with naphthalene SOA exhibiting the most pronounced effects, likely due to the formation of nitroaromatics. Together, these results suggest that precursor identity may be more influential than reaction condition in determining SOA health effects, demonstrating the importance of sources, such as incomplete combustion, to aerosol toxicity. In the context of other PM sources, all SOA systems with the exception of naphthalene SOA were less DTT active than ambient sources related to incomplete combustion, including diesel and gasoline combustion as well as biomass burning. Finally, naphthalene SOA was as DTT active as biomass burning aerosol, which was found to be the most DTT active OA source in a previous ambient study. These results highlight a need to consider SOA contributions (particularly from anthropogenic hydrocarbons) to health effects in the context of hydrocarbon emissions, SOA yields, and other PM sources.

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