scholarly journals Aerosol optical properties during the 2004 New England Air Quality Study-Intercontinental Transport and Chemical Transformation: Gulf of Maine surface measurements-Regional and case studies

2006 ◽  
Vol 111 (D23) ◽  
Author(s):  
Berko Sierau ◽  
David S. Covert ◽  
Derek J. Coffman ◽  
Patricia K. Quinn ◽  
Timothy S. Bates
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
New England ◽  
Case Studies ◽  
Chemical Transformation ◽  
Gulf Of Maine ◽  
Aerosol Optical Properties ◽  
Intercontinental Transport ◽  
Surface Measurements ◽  
Quality Study

scholarly journals Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016

2019 ◽  
Vol 19 (14) ◽  
pp. 9181-9208 ◽  
Author(s):  
Kristina Pistone ◽  
Jens Redemann ◽  
Sarah Doherty ◽  
Paquita Zuidema ◽  
Sharon Burton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Case Studies ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol

Abstract. The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol–cloud–radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400>0.4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences.

scholarly journals Shipboard multisensor merged wind profiles from the New England Air Quality Study 2004

2007 ◽  
Vol 112 (D10) ◽  
Author(s):  
D. E. Wolfe ◽  
W. A. Brewer ◽  
S. C. Tucker ◽  
A. B. White ◽  
D. E. White ◽  
...  
Keyword(s):  
Air Quality ◽  
New England ◽  
Quality Study ◽  
Wind Profiles

Interactive Aerosol Feedbacks on Photolysis Rates in the GEM-MACH Air Quality Model for an Athabasca Oil-Sands Modelling Study

2020 ◽  
Author(s):  
Mahtab Majdzadeh ◽  
Craig Stroud ◽  
Ayodeji Akingunola ◽  
Paul Makar ◽  
Christopher Sioris ◽  
...  
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
Radiative Transfer ◽  
Forest Fire ◽  
Lookup Table ◽  
Aerosol Optical Properties ◽  
Extinction Efficiency ◽  
Scattering Cross ◽  
Photolysis Rates ◽  
On Line

<p>The radiative transfer module of an on-line chemical transport models requires input data from aerosol extinction efficiency, single scatter albedo and asymmetry factor, in order to predict the radiative state of the atmosphere. These aerosol optical properties (aerosol optical depth, AOD), may be integrated vertically for comparison to satellite observations. These optical effects may also influence the shorter wavelengths associated with atmospheric gas photolysis, influencing atmospheric reactivity. These processes may be harmonized in an on-line reaction transport model, such as Environment and Climate Change Canada’s GEM-MACH (GEM: Global Environmental Multi-scale – MACH: Modelling Air quality and Chemistry). Previous photolysis routine in the radiative transfer module, MESSY-JVAL (Modular Earth Sub-Model System), in GEM-MACH, made use of a climatology of aerosol optical properties, and the previous on-line version made use of a homogeneous mixture Mie code for meteorological radiative transfer calculations.</p><p>We calculated a new lookup table for the extinction efficiency, absorption and scattering cross sections of each aerosol type. The new version of MESSY-JVAL uses GEM-MACH predicted aerosol size distributions, chemical composition and relative humidity in each vertical column at each time step as input, reads aerosol absorption and scattering cross section data from the new lookup table and calculates aerosol optical properties, that are then used to modify both photolysis and meteorological radiative transfer calculations.</p><p>In order to evaluate these modifications to the model, we performed a series of simulations with GEM-MACH with wildfire emissions inputs from the Canadian Forest Fire Emissions Prediction System (CFFEPS) and compared the model AOD output with satellite and AERONET (Aerosol Robotic Network) measurement data. Comparison of the hourly AERONET and monthly-averaged satellite AOD demonstrates major improvements in the revised model AOD predictions. The impact of the updated photolysis rates and meteorological radiative transfer calculations on predictions of oxidant mixing ratios and rates of pollutant oxidation (nitrogen dioxide conversion to nitric acid) will be assessed both within and below the forest fire plume.</p>

Variability of trends observed in Atmospheric Aerosol optical properties over Pune, India

2020 ◽  
Author(s):  
Sudeep Das ◽  
Govindan Pandithurai
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
Role Model ◽  
Anthropogenic Activities ◽  
Sea Salt ◽  
Negative Slope ◽  
Average Height ◽  
Aerosol Optical Properties ◽  
The City ◽  
Monthly Variations

<p>Long term trends of various aerosol optical properties are observed over the city of Pune, the ninth most populated city in India using ground and satellite based instruments such as AERONET, MODIS (Aqua and Terra), MISR, CALIOP and reanalysis tool MERRA. Annually, the Aerosol Optical Depth is observed to be increasing over all the types of instruments (2004-17) with values of 0.01 to 0.006 yr<sup>-1</sup>, whereas the Angstrom exponent has a negative slope (AERONET) which suggests that the fine aerosols are decreasing. Single scattering albedo (SSA) is also increasing (0.00657 yr<sup>-1</sup>), which means the emission of smaller darker particles like soot has decreased over the years. MISR shows that the Absorbing AOD trend is decreasing in the overall study period (-0.0001237 yr<sup>-1</sup>). All these annual trends are related to anthropogenic activities and show differing trends before and after 2008, the year when various pollution counter measures were introduced mainly in Pune and also in various nearby areas. After 2008, the AOD increasing slope reduces, and the AAOD reverses the trend from positive to a negative slope. The average height till various kinds of aerosols reach and their vertical profile is studied using CALIOP data. Monthly variations of AOD and their vertical distribution also observed and discussed. Aerosol characterization is done using the MERRA tool into dust, sea salt, sulfates, elementary carbon, and organic carbon. Their monthly variations are explained by source characterizations using the HySplit model. In summer, air from the Arabian sea brings in dust and sea salt into the city and in winter, aerosols come from central India dominantly as carbon and sulfates changing the air quality over there. This study lays its stress on the fact that even though aerosols cover over a city is mostly non-local, anthropogenic activities of that area do play a significant role and here the city of Pune is a role model to show how measures can be taken to improve air quality over any urban area.</p>

scholarly journals Analysis of the isoprene chemistry observed during the New England Air Quality Study (NEAQS) 2002 intensive experiment

2006 ◽  
Vol 111 (D23) ◽  
Author(s):  
James M. Roberts ◽  
Mathew Marchewka ◽  
Steven B. Bertman ◽  
Paul Goldan ◽  
William Kuster ◽  
...  
Keyword(s):  
Air Quality ◽  
New England ◽  
Quality Study

scholarly journals Wildfire particulate matter in Europe during summer 2003: meso-scale modeling of smoke emissions, transport and radiative effects

2007 ◽  
Vol 7 (2) ◽  
pp. 4705-4760 ◽  
Author(s):  
A. Hodzic ◽  
S. Madronich ◽  
B. Bohn ◽  
S. Massie ◽  
L. Menut ◽  
...  
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
Radiative Forcing ◽  
Anthropogenic Sources ◽  
Radiative Effects ◽  
Aerosol Optical Properties ◽  
Smoke Particles ◽  
Fire Source ◽  
Photolysis Rates ◽  
Meso Scale

Abstract. The present study investigates effects of wildfire emissions on air quality in Europe during an intense fire season that occurred in summer 2003. A meso-scale chemistry transport model CHIMERE is used, together with ground based and satellite aerosol optical measurements, to assess the dispersion of fire emissions and to quantify the associated radiative effects. The model has been improved to take into account the MODIS daily smoke emission inventory as well as the injection altitude of smoke particles. The simulated aerosol optical properties are inputted into a radiative transfer model to estimate (off-line) the effects of smoke particles on photolysis rates and atmospheric radiative forcing. We have found that wildfires generated comparable amounts of primary aerosol pollutants (220 kTons of PM2.5, fine particles) to anthropogenic sources during August 2003, and caused significant changes in aerosol optical properties not only close to the fire source regions, but also over a large part of Europe as a result of the long-range transport of smoke. Including these emissions into the model significantly improved its performance in simulating observed aerosol concentrations and optical properties. Quantitative comparison with MODIS and POLDER data during the major fire event (3–8 August) showed the ability of the model to reproduce high aerosol optical thickness (AOT) over Northern Europe caused by the advection of the smoke plume from the Portugal source region. Statistical analyses of model simulations showed a better agreement with observed AOT data at AERONET ground stations and suggest that wildfire emissions are responsible for a 30% enhancement in mean AOT values during the heat-wave episode. The implications for air quality over a large part of Europe are significant during this episode. First, directly, the modeled wildfire emissions caused an increase in average PM10 ground concentrations from 20 to 200%. The largest enhancement in PM10 concentrations stayed however confined within a 200 km area around the fire source locations and reached up to 40 μ g/m3. Second, indirectly, the presence of elevated smoke layers over Europe significantly altered atmospheric radiative properties: the model results imply a 10 to 30% decrease in photolysis rates and an increase in atmospheric radiative forcing of 10–35 Wm−2 during the period of strong fire influence throughout a large part of Europe. These results suggest that sporadic wildfire events may have significant effects on regional photochemistry and atmospheric stability, and need to be considered in current chemistry-transport models.

scholarly journals Identifying Chemical Aerosol Signatures using Optical Suborbital Observations: How much can optical properties tell us about aerosol composition?

2021 ◽  
Author(s):  
Meloë S. F. Kacenelenbogen ◽  
Qian Tan ◽  
Sharon P. Burton ◽  
Otto P. Hasekamp ◽  
Karl D. Froyd ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Optical Properties ◽  
Air Quality ◽  
Chemical Transport ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Aerosol Composition ◽  
Ångström Exponent

Abstract. Improvements in air quality and Earth’s climate predictions require improvements of the aerosol speciation in chemical transport models, using observational constraints. Aerosol speciation (e.g., organic aerosols, black carbon, sulfate, nitrate, ammonium, dust or sea salt) is typically determined using in situ instrumentation. Continuous, routine surface network aerosol composition measurements are not uniformly widespread over the globe. Satellites, on the other hand, can provide a maximum coverage of the horizontal and vertical atmosphere but observe aerosol optical properties (and not aerosol speciation) based on remote sensing instrumentation. Combinations of satellite-derived aerosol optical properties can inform on air mass aerosol types (AMTs e.g., clean marine, dust, polluted continental). However, these AMTs are subjectively defined, might often be misclassified and are hard to relate to the critical parameters that need to be refined in models. In this paper, we derive AMTs that are more directly related to sources and hence to speciation. They are defined, characterized, and derived using simultaneous in situ gas-phase, chemical and optical instruments on the same aircraft during the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS, US, summer of 2013). First, we prescribe well-informed AMTs that display distinct aerosol chemical and optical signatures to act as a training AMT dataset. These in situ observations reduce the errors and ambiguities in the selection of the AMT training dataset. We also investigate the relative skill of various combinations of aerosol optical properties to define AMTs and how much these optical properties can capture dominant aerosol speciation. We find distinct optical signatures for biomass burning (from agricultural or wildfires), biogenic and dust-influence AMTs. Useful aerosol optical properties to characterize these signatures are the extinction angstrom exponent (EAE), the single scattering albedo, the difference of single scattering albedo in two wavelengths, the absorption coefficient, the absorption angstrom exponent (AAE), and the real part of the refractive index (RRI). We find that all four AMTs studied when prescribed using mostly airborne in situ gas measurements, can be successfully extracted from at least three combinations of airborne in situ aerosol optical properties (e.g., EAE, AAE and RRI) over the US during SEAC4RS. However, we find that the optically based classifications for BB from agricultural fires and polluted dust include a large percentage of misclassifications that limit the usefulness of results relating to those classes. The technique and results presented in this study are suitable to develop a representative, robust and diverse source-based AMT database. This database could then be used for widespread retrievals of AMTs using existing and future remote sensing suborbital instruments/networks. Ultimately, it has the potential to provide a much broader observational aerosol data set to evaluate chemical transport and air quality models than is currently available by direct in situ measurements. This study illustrates how essential it is to explore existing airborne datasets to bridge chemical and optical signatures of different AMTs, before the implementation of future spaceborne missions (e.g., the next generation of Earth Observing System (EOS) satellites addressing Aerosol, Cloud, Convection and Precipitation (ACCP) designated observables).

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