Function and Performance of a Low Turbulence Inlet for Sampling Supermicron Particles from Aircraft Platforms

Wilson, J. C.; Lafleu, B. G.; Hilbert, H.; Seebaugh, W. R.; Fox, J. R.; Gesler, D.W.; Brock, C. A.; Huebert, B. J.; Mullen, Jon

doi:10.1080/027868290500841

Cited by 63 publications

(61 citation statements)

References 10 publications

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“…The measured optical properties are highly dependent on the extent to which the coarse mode is measured . During Fennec, Grimm OPCs were setup behind two different Rosemount inlets, while a third was set up behind the fully characterised LTI inlet Wilson et al, 2004). This has enabled the proportion of the ambient size distribution passing through the Rosemount inlets on the FAAM aircraft to be examined for the first time, and here we use this information to assess the impact on the measured optical properties.…”

Section: Inletsmentioning

confidence: 99%

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

et al. 2013

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Abstract. New in-situ aircraft measurements of Saharan dust originating from Mali, Mauritania and Algeria taken during the Fennec 2011 aircraft campaign over a remote part of the Sahara Desert are presented. Size distributions extending to 300 µm are shown, representing measurements extending further into the coarse mode than previously published for airborne Saharan dust. A significant coarse mode was present in the size distribution measurements with effective diameter (d eff ) from 2.3 to 19.4 µm and coarse mode volume median diameter (d vc ) from 5.8 to 45.3 µm. The mean size distribution had a larger relative proportion of coarse mode particles than previous aircraft measurements. The largest particles (with d eff > 12 µm, or d vc > 25 µm) were only encountered within 1 km of the ground. Number concentration, mass loading and extinction coefficient showed inverse relationships to dust age since uplift. Dust particle size showed a weak exponential relationship to dust age. Two cases of freshly uplifted dust showed quite different characteristics of size distribution and number concentration.Single Scattering Albed (SSA) values at 550 nm calculated from the measured size distributions revealed high absorption ranging from 0.70 to 0.97 depending on the refractive index. SSA was found to be strongly related to d eff . New instrumentation revealed that direct measurements, behind Rosemount inlets, overestimate SSA by up to 0.11 when d eff is greater than 2 µm. This is caused by aircraft inlet inefficiencies and sampling losses. Previous measurements of SSA from aircraft measurements may also have been overestimates for this reason. Radiative transfer calculations indicate that the range of SSAs during Fennec 2011 can lead to underestimates in shortwave atmospheric heating rates by 2.0 to 3.0 times if the coarse mode is neglected. This will have an impact on Saharan atmospheric dynamics and circulation, which should be taken into account by numerical weather prediction and climate models.

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Section: Inletsmentioning

confidence: 99%

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

et al. 2013

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“…9 plots vertical profiles of NASA P-3B (red) and the NOAA WP3D (blue) supermicrometer volume (V coa ). Mean and median volume concentrations are likely higher aboard the NOAA WP-3D because of the use of an active low-turbulence inlet (Huebert et al, 2004b;Wilson et al, 2004) with a 50 % passing efficiency larger than the passive solid diffuser inlets used aboard the NASA DC-8 and P-3B . Intense plumes of coarse mode aerosol were rare during ARCTAS, however the WP-3D did encounter one such plume with 60-s average volume greater than 50 µm 3 m −3 .…”

Section: Mineral Dust Over the Western Arcticmentioning

confidence: 99%

“…The DC-8 solid diffuser inlet (UH-SDI) is that described in McNaughton et al (2007), whereas the P-3B employed a newly fabricated inlet with characteristics identical to those of the original UH-SDI. Aerosol size distributions between 0.004 and 7.0 µm were measured on board the NOAA WP-3D using a 5-channel condensation particle counter (CPC) (Brock et al, 2000) and optical particle counters operating behind a low-turbulence inlet (Huebert et al, 2004b;Wilson et al, 2004).…”

Section: Instrumentationmentioning

confidence: 99%

Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns

et al. 2011

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Abstract. In the spring of 2008 NASA and NOAA funded the ARCTAS and ARCPAC field campaigns as contributions to POLARCAT, a core IPY activity. During the campaigns the NASA DC-8, P-3B and NOAA WP-3D aircraft conducted over 160 h of in-situ sampling between 0.1 and 12 km throughout the Western Arctic north of 55 • N (i.e. Alaska to Greenland). All aircraft were equipped with multiple wavelength measurements of aerosol optics, trace gas and aerosol chemistry measurements, as well as direct measurements of the aerosol size distributions and black carbon mass. Late April of 2008 proved to be exceptional in terms of Asian biomass burning emissions transported to the Western Arctic. Though these smoke plumes account for only 11-14 % of the samples within the Western Arctic domain, they account for 42-47 % of the total burden of black carbon. Dust was also commonly observed but only contributes to 4-12 % and 3-8 % of total light absorption at 470 and 530 nm wavelengths above 6 km. Below 6 km, light absorption by carbonaceous aerosol derived from urban/industrial and biomass burning emissions account for 97-99 % of total light absorption by aerosol. Stratifying the data to reduce the influence of dust allows us to determine mass absorption efficiencies for black carbon of 11.2±0.8, 9.5±0.6 and 7.4±0.7 m 2 g −1 at 470, 530 and 660 nm waveCorrespondence to: C. S. McNaughton (csmcnaug@hawaii.edu) lengths. These estimates are consistent with 35-80 % enhancements in 530 nm absorption due to clear or slightly absorbing coatings of pure black carbon particulate. Assuming a 1/λ wavelength dependence for BC absorption, and assuming that refractory aerosol (420 • C, τ = 0.1 s) in lowdust samples is dominated by brown carbon, we derive mass absorption efficiencies for brown carbon of 0.83±0.15 and 0.27±0.08 m 2 g −1 at 470 and 530 nm wavelengths. Estimates for the mass absorption efficiencies of Asian dust are 0.034 m 2 g −1 and 0.017 m 2 g −1 . However the absorption efficiency estimates for dust are highly uncertain due to the limitations imposed by PSAP instrument noise. In-situ ARC-TAS/ARCPAC measurements during the IPY provide valuable constraints for absorbing aerosol over the Western Arctic, species which are currently poorly simulated over a region that is critically under-sampled.

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“…The SP2 sampled ambient aerosol behind a 1 µm particle impactor through a low-turbulence inlet (LTI) Wilson et al, 2004). The sampling inlet was designed and mounted to the aircraft in a manner to sample the ambient air stream without contamination from the boundary layer along the skin of the aircraft.…”

Section: Aircraft Measurementsmentioning

confidence: 99%

Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic

et al. 2010

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Abstract. Understanding the processes controlling black carbon (BC) in the Arctic is crucial for evaluating the impact of anthropogenic and natural sources of BC on Arctic climate. Vertical profiles of BC mass loadings were observed from the surface to near 7-km altitude in April 2008 using a Single-Particle Soot Photometer (SP2) during flights on the NOAA WP-3D research aircraft from Fairbanks, Alaska. These measurements were conducted during the NOAAsponsored Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project. In the free troposphere, the Arctic air mass was influenced by long-range transport from biomass-burning and anthropogenic source regions at lower latitudes especially during the latter part of the campaign. Average BC mass mixing ratios peaked at about 150 ng BC (kg dry air ) −1 near 5.5 km altitude in the aged Arctic air mass and 250 ng kg −1 at 4.5 km in biomassburning influenced air. BC mass loadings were enhanced by up to a factor of 5 in biomass-burning influenced air compared to the aged Arctic air mass. At the bottom of some of the profiles, positive vertical gradients in BC were observed over the sea-ice. The vertical profiles generally occurred in the vicinity of open leads in the sea-ice. In the aged ArcticCorrespondence to: J. R. Spackman (ryan.spackman@noaa.gov) air mass, BC mass loadings more than doubled with increasing altitude within the ABL and across the boundary layer transition while carbon monoxide (CO) remained constant. This is evidence for depletion of BC mass in the ABL. BC mass loadings were positively correlated with O 3 in ozone depletion events (ODEs) for all the observations in the ABL. Since bromine catalytically destroys ozone in the ABL after being released as molecular bromine in regions of new seaice formation at the surface, the BC-O 3 correlation suggests that BC particles were removed by a surface process such as dry deposition. We develop a box model to estimate the dry deposition flux of BC mass to the snow constrained by the vertical profiles of BC mass in the ABL. Open leads in the sea-ice may increase vertical mixing and entrainment of pollution from the free troposphere possibly enhancing the deposition of BC aerosol to the snow.

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Function and Performance of a Low Turbulence Inlet for Sampling Supermicron Particles from Aircraft Platforms

Cited by 63 publications

References 10 publications

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns

Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic

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