Photoacoustic insight for aerosol light absorption aloft from meteorological aircraft and comparison with particle soot absorption photometer measurements: DOE Southern Great Plains climate research facility and the coastal stratocumulus imposed perturbation experiments

Arnott, W. P.; Walker, John W.; Moosmüller, Hans; Elleman, Robert; Jonsson, Haflidi H.; Buzorius, G.; Conant, William C.; Flagan, Richard C.; Seinfeld, John H.

doi:10.1029/2005jd005964

Cited by 58 publications

(52 citation statements)

References 44 publications

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“…The basic principles of the PAS technique applied to aerosol measurements have been discussed at length previously (e.g., Arnott et al 2006) and are only briefly covered here. The photoacoustic technique involves exposing an absorbing aerosol to an intensity-modulated laser beam.…”

Section: Methodsmentioning

confidence: 99%

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Limitations of the Photoacoustic Technique for Aerosol Absorption Measurement at High Relative Humidity

Langridge

Richardson

Lack

et al. 2013

Aerosol Science and Technology

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Laboratory experiments were conducted to assess the suitability of photoacoustic spectroscopy (PAS) for aerosol absorption measurement at high relative humidity (RH). Initial experiments characterized the PAS sensitivity that increased strongly by ∼1.25 between dry conditions and 90% RH. Correction procedures were validated by measuring RH-independent absorption for hydrophobic absorbing particles. Absorption measured by PAS for a range of hygroscopic particles, including different morphologies, hygroscopicities, and absorbing entities, showed strong low biases at high RH (down to 0.4 at 90% RH). The bias was due to water evaporation impacting the PAS signal. Cooling samples to lower absolute humidity while maintaining a constant RH did not significantly reduce the bias magnitude within the temperature range 11-25• C. The magnitude and RH dependence of the bias were not reproduced well using a model of PAS response incorporating coupled heat and mass transfer in the transition regime. This was attributed, in part, to uncertainty related to changes in the water mass accommodation coefficient with RH. Given our inability to correct for evaporation-induced bias effects accurately, or reduce their magnitude experimentally, we conclude that PAS is not a technique well suited to the measurement of absorption at high RH. In order to minimize RH-related errors in PAS measurements made under notionally "dry" conditions, we recommend operation in the RH range 10-30%.

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Section: Methodsmentioning

confidence: 99%

“…Equation (1) reproduced from Arnott et al (2006) shows the key factors linking the aerosol absorption coefficient, β abs , to the PAS microphone response, P mic :…”

Section: Pas Correction Proceduresmentioning

confidence: 99%

Limitations of the Photoacoustic Technique for Aerosol Absorption Measurement at High Relative Humidity

Langridge

Richardson

Lack

et al. 2013

Aerosol Science and Technology

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“…Uncertainties on mass derived from FSN measurements are therefore dependent on the fit to empirical data. Photo-acoustic absorption spectroscopy (PAS) is a more accurate, precise and sensitive measure of absorption compared to the filterbased techniques (Arnott et al, 2006;Lack et al, 2006;Lack et al, 2008b). Laser induced incandescence (LII) is probably the most fundamental measurement of the strongly light absorbing carbon material, although this technique requires very careful calibration and operation (Cross et al, 2010;Moteki and Kondo, 2010).…”

Section: Definition and Measurement Of Black Carbonmentioning

confidence: 99%

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

2012

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Abstract. The International Maritime Organization (IMO) has moved to address the health and climate impact of the emissions from the combustion of low-quality residual fuels within the commercial shipping industry. Fuel sulfur content (F S ) limits and an efficiency design index for future ships are examples of such IMO actions. The impacts of black carbon (BC) emissions from shipping are now under review by the IMO, with a particular focus on the potential impacts of future Arctic shipping.Recognizing that associating impacts with BC emissions requires both ambient and onboard observations, we provide recommendations for the measurement of BC. We also evaluate current insights regarding the effect of ship speed (engine load), fuel quality and exhaust gas scrubbing on BC emissions from ships. Observations demonstrate that BC emission factors (EF BC ) increases 3 to 6 times at very low engine loads (<25 % compared to EF BC at 85-100 % load); absolute BC emissions (per nautical mile of travel) also increase up to 100 % depending on engine load, even with reduced load fuel savings. If fleets were required to operate at lower maximum engine loads, presumably associated with reduced speeds, then engines could be re-tuned, which would reduce BC emissions.Ships operating in the Arctic are likely running at highly variable engine loads (25-100 %) depending on ice conditions and ice breaking requirements. The ships operating at low load may be emitting up to 50 % more BC than they would at their rated load. Such variable load conditions make it difficult to assess the likely emissions rate of BC.Current fuel sulfur regulations have the effect of reducing EF BC by an average of 30 % and potentially up to 80 % regardless of engine load; a removal rate similar to that of scrubbers.Uncertainties among current observations demonstrate there is a need for more information on a) the impact of fuel quality on EF BC using robust measurement methods and b) the efficacy of scrubbers for the removal of particulate matter by size and composition.

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“…The eBC, B scat and B abs are derived from the PAX, a sensor that evolved from the Photoacoustic Soot Spectrometer (PASS) developed at the University of Nevada (e.g., Arnott et al, 2005Arnott et al, , 2006Moosmüller et al, 2009) and commercialized by Droplet Measurement Technologies (Chan et al, 2011;Holder et al, 2014;Liu et al, 2014;Nakayama et al, 2015). The PAX performs simultaneous measurements of aerosol scattering and absorption coefficients using a single diode laser modulated at approximately 1500 Hz.…”

Section: The Photoacoustic Extinctiometermentioning

confidence: 99%

“…The PAX was connected to the cyclone by 3/8" conductive tubing. Transmission losses are insignificant at the flow rate of 1 Lpm, based on calculations made using the Aerocalc program developed by Baron and Willeke (2001).…”

Section: The Photoacoustic Extinctiometermentioning

confidence: 99%

Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City

et al. 2015

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Abstract. The Mexico City metropolitan area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short-lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e., ozone (O 3) and carbon monoxide (CO), but particulate matter (PM 2.5 and PM 10 ) and black carbon (BC) have shown a less positive response to mitigation strategies that have been in place for almost 3 decades. For the first time, extended measurements of equivalent black carbon (eBC), derived from light absorption measurements, have been made using a Photoacoustic Extinctiometer (PAX) over a 13 month period from March 2013 through March 2014. The daily trends in workdays (Monday through Saturday) and Sunday eBC, PM 2.5 and the co-pollutants CO, O 3 and NO x are evaluated with respect to the three primary seasons in the MCMA: rainy, cold and dry and warm and dry.The maximum values in all of the particle and gas concentrations were significantly larger (Student's t test, P <0.05) during the dry periods than in the rainy season. The changes from rainy to dry seasons for eBC, PM 2.5 , CO, O 3 and NO x were 8.8 to 13.1 µg m −3 (40 %), 49 to 73 µg m −3 (40 %), 2.5 to 3.8 ppm (40 %), 73 to 100 ppb (30 %) and 144 to 252 ppb (53 %), respectively.The primary factors that lead to these large changes between the wet and dry seasons are the accelerated vertical mixing of boundary layer and free tropospheric air by the formation of clouds that dilutes the concentration of the SLCPs, the decreased actinic flux that reduces the production of ozone by photochemical reactions and the heavy, almost daily rain that removes particulate matter.A significant "weekend effect" was also identified, particularly the decrease in BC due to fewer large transport vehicles that are fueled by diesel, which produces a large fraction of the BC. The other co-pollutant concentrations are also significantly less on weekends except for O 3 that shows no change in maximum values from workdays to Sundays. This lack of change is a result of the balancing effects of lower precursor gases, i.e., VOCs, offset by lower concentrations of NO x , that is an O 3 inhibitor.A comparison of the average maximum value of eBC measured during the 1 year period of the current study, with maximum values measured in shorter field campaigns in 2000 and 2006, shows no significant change in the eBC emissions over a 14 year period. This suggests that new methods may need to be developed that can decrease potentially toxic levels of this particulate pollutant. BackgroundShort-lived climate pollutants (SLCP) are those gases and particles whose atmospheric lifetimes range from less than a day to a few years (Shindell et al., 2012;Bowerman et al., 2013) and exert a positive radiative forcing to the global climate. These pollutants, black carbon (BC), methane (CH 4 ), tropospheric ozone (O 3 ) and selected hydrofluorocarbons (HFCs), also impact the environment and ...

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Photoacoustic insight for aerosol light absorption aloft from meteorological aircraft and comparison with particle soot absorption photometer measurements: DOE Southern Great Plains climate research facility and the coastal stratocumulus imposed perturbation experiments

Cited by 58 publications

References 44 publications

Limitations of the Photoacoustic Technique for Aerosol Absorption Measurement at High Relative Humidity

Limitations of the Photoacoustic Technique for Aerosol Absorption Measurement at High Relative Humidity

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City

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