A Compact Lightweight Aerosol Spectrometer Probe (CLASP)

Hill, M. P.; Brooks, Ian M.; Norris, S. J.; Smith, M. H.; Leeuw, G. de

doi:10.1175/2008jtecha1051.1

Cited by 34 publications

(46 citation statements)

References 11 publications

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“…The temporal resolution of the instrument is 10 Hz, making it well suited for aircraft sampling. In-depth information about the workings of the CLASP is given by Hill et al (2008). The CLASP OPC and the CPCs were placed on board the helicopter in the left back seat, on a common instrumentation rack (Fig.…”

Section: Helicopter-based Particle Countersmentioning

confidence: 99%

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

et al. 2013

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Abstract. Unique measurements of vertical size-resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from on board the Swedish icebreaker Oden, and provided both ship-and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Within the lowermost couple hundred metres, transport from the marginal ice zone (MIZ), condensational growth and cloud processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore long-range transport plumes are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, such plumes can influence the radiative balance of the planetary boundary layer (PBL) by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles could be in biological processes, both primary and secondary, within the open leads between the pack ice and/or along the MIZ. In general, local sources, in combination with upstream boundary-layer transport of precursor gases from the MIZ, are considered to constitute the origin of cloud condensation nuclei (CCN) particles and thus be of importance for the formation of interior Arctic low-level clouds during summer, and subsequently, through cloud influences, for the melting and freezing of sea ice.

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Section: Helicopter-based Particle Countersmentioning

confidence: 99%

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

et al. 2013

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“…In order to estimate the production of sea spray aerosol from individual wave breaking events, a Compact Lightweight Aerosol Spectrometer Probe (CLASP) (Hill et al, 2008) was mounted on a small buoy with an inlet approximately 1 m above the surface (Fig. 1).…”

Section: Measurementsmentioning

confidence: 99%

“…CLASP provides a 16-channel size spectrum at ambient relative humidity covering the size range 0.12 < R amb < 9.25 µm at a sample rate of 10 Hz (Hill et al, 2008). The inlet is 0.25 m in length, with one 60 degree bend; particle losses to the walls of the inlet are negligible for particles with radii below 1 µm, 10 % at 3 µm and 20 % at 5 µm.…”

Section: Measurementsmentioning

confidence: 99%

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Near-surface measurements of sea spray aerosol production over whitecaps in the open ocean

et al. 2013

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Abstract. Simultaneous measurements of near-surface aerosol (0.12 < R < 9.25 µm) and bubble spectra (13 < R < 620 µm) were made during five buoy deployments in the open ocean of the North Atlantic and used to estimate aerosol fluxes per unit area of whitecap. The measurements were made during two cruises as part of the Sea Spray, Gas Flux, and Whitecaps (SEASAW) project, a UK contribution to the international Surface Ocean Lower Atmosphere Study (SOLAS) program. The mean bubble number concentrations for each deployment are in broad agreement with other open ocean spectra and are consistently one to two orders of magnitude lower than surf zone studies. Production fluxes per unit area of whitecap are estimated from the mean aerosol concentration for each buoy deployment. They are found to increase with wind speed, and span the range of values found by previous laboratory and surf-zone studies for particles with radius at 80 % relative humidity, R 80 < 1 µm, but to drop off more rapidly with increasing particle size for larger particles. Estimates of the mean sea spray flux were made by scaling the whitecap production fluxes with in situ estimates of whitecap fraction. The sea spray fluxes are also compared with simultaneous individual eddy covariance flux estimates, and with a sea spray source function derived from them.

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“…Small weather balloons are excellent platforms for temperature, ozone, and water vapor profile measurements. However, only a few particle sensors suitable for balloon deployment have been described in the literature (Hofmann et al 1975;Hayashi et al 1998;Sugita et al 1999;Deshler et al 2003;Kasai et al 2003;Iwasaki et al 2007;Hill et al 2008). Most of these sensors are not capable of measuring particles below 150-nm diameter and/or are not suitable for disposable sondes.…”

Section: Introductionmentioning

confidence: 99%

A High-Sensitivity Low-Cost Optical Particle Counter Design

Gao

Perring

Thornberry

et al. 2013

Aerosol Science and Technology

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We report the design of a small optical particle counter with high sensitivity and low construction cost for atmospheric aerosol measurements. Particle sensing is based on the detection of the forward scattering of laser light. The separation of the laser beam and scattered light is achieved with a novel yet simple optical system. A laboratory prototype system with a 405-nm laser and photomultiplier tube detector has successfully detected polystyrene latex particles as small as 125 nm in diameter with unit efficiency. Theoretical calculations suggest that a lower detectable size limit of 100 nm can be achieved with reduction of background scattered light. The new counter will be useful in a variety of ground-based as well as small balloon-borne applications such as vertical profiling and in situ measurement of particles from explosive volcanic eruptions.

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A Compact Lightweight Aerosol Spectrometer Probe (CLASP)

Cited by 34 publications

References 11 publications

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

Near-surface measurements of sea spray aerosol production over whitecaps in the open ocean

A High-Sensitivity Low-Cost Optical Particle Counter Design

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