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Full-Text Articles in Physics
Optical-Chemical-Microphysical Relationships And Closure Studies For Mixed Carbonaceous Aerosols Observed At Jeju Island; 3-Laser Photoacoustic Spectrometer, Particle Sizing, And Filter Analysis, B. A. Flowers, M. K. Dubey, C. Mazzoleni, E. A. Stone, J. J. Schauer, S. W. Kim, S. C. Yoon
Optical-Chemical-Microphysical Relationships And Closure Studies For Mixed Carbonaceous Aerosols Observed At Jeju Island; 3-Laser Photoacoustic Spectrometer, Particle Sizing, And Filter Analysis, B. A. Flowers, M. K. Dubey, C. Mazzoleni, E. A. Stone, J. J. Schauer, S. W. Kim, S. C. Yoon
Michigan Tech Publications
Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX) field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3), chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings) on light absorption that traditional filter-based instruments are unable to address. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 74% of the deployment days, showing large variations in their measured chemical and optical …
A New Method For Deriving Aerosol Solar Radiative Forcing And Its First Application Within Milagro/Intex-B, K. S. Schmidt, P. Pilewskie, R. Bergstrom, O. Coddington, J. Redemann, J. Livingston, P. Russell, E. Bierwirth, M. Wendisch, W. Gore, M. K. Dubey, C. Mazzoleni
A New Method For Deriving Aerosol Solar Radiative Forcing And Its First Application Within Milagro/Intex-B, K. S. Schmidt, P. Pilewskie, R. Bergstrom, O. Coddington, J. Redemann, J. Livingston, P. Russell, E. Bierwirth, M. Wendisch, W. Gore, M. K. Dubey, C. Mazzoleni
Michigan Tech Publications
We introduce a method for deriving aerosol spectral radiative forcing along with single scattering albedo, asymmetry parameter, and surface albedo from airborne vertical profile measurements of shortwave spectral irradiance and spectral aerosol optical thickness. The new method complements the traditional, direct measurement of aerosol radiative forcing efficiency from horizontal flight legs below gradients of aerosol optical thickness, and is particularly useful over heterogeneous land surfaces and for homogeneous aerosol layers where the horizontal gradient method is impractical. Using data collected by the Solar Spectral Flux Radiometer (SSFR) and the Ames Airborne Tracking Sunphotometer (AATS-14) during the MILAGRO (Megacity Initiative: Local …
Brown Carbon In Tar Balls From Smoldering Biomass Combustion, R. K. Chakrabarty, H. Moosmüller, L. W.A. Chen, K. Lewis, W. P. Arnott, C. Mazzoleni, M. K. Dubey, C. E. Wold, W. M. Hao, S. M. Kreidenweis
Brown Carbon In Tar Balls From Smoldering Biomass Combustion, R. K. Chakrabarty, H. Moosmüller, L. W.A. Chen, K. Lewis, W. P. Arnott, C. Mazzoleni, M. K. Dubey, C. E. Wold, W. M. Hao, S. M. Kreidenweis
Michigan Tech Publications
We report the direct observation of laboratory production of spherical, carbonaceous particles-"tar balls"-from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Ångström coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent imaginary part of its refractive index-optically defined as "brown carbon"-is an important component of tar balls. The spectrum of the imaginary parts of their complex refractive indices can be described with a Lorentzian-like model with an effective resonance wavelength in the ultraviolet (UV) spectral region. Sensitivity calculations for aerosols containing traditional OC (no absorption at visible …
Observations Of Turbulence-Induced New Particle Formation In The Residual Layer, B. Wehner, H. Siebert, A. Ansmann, F. Ditas, P. Seifert, F. Stratmann, A. Wiedensohler, A. Apituley, R. A. Shaw, H. E. Manninen, M. Kulmala
Observations Of Turbulence-Induced New Particle Formation In The Residual Layer, B. Wehner, H. Siebert, A. Ansmann, F. Ditas, P. Seifert, F. Stratmann, A. Wiedensohler, A. Apituley, R. A. Shaw, H. E. Manninen, M. Kulmala
Michigan Tech Publications
Aerosol particle measurements in the atmospheric boundary layer performed by a helicopter-borne measurement payload and by a lidar system from a case study during the IMPACT field campaign in Cabauw (NL) are presented. Layers of increased number concentrations of ultrafine particles were observed in the residual layer, indicating relatively recent new-particle formation. These layers were characterized by a sub-critical Richardson number and concomitant increased turbulence. Turbulent mixing is likely to lead to local supersaturation of possible precursor gases which are essential for new particle formation. Observed peaks in the number concentrations of ultrafine particles at ground level are connected to …
Heterogeneous Freezing Of Droplets With Immersed Mineral Dust Particles - Measurements And Parameterization, D. Niedermeier, S. Hartmann, R. A. Shaw, D. Covert, T. F. Mentel, J. Schneider, L. Poulain, P. Reitz, C. Spindler, T. Clauss, A. Kiselev, E. Hallbauer, H. Wex, K. Mildenberger, F. Stratmann
Heterogeneous Freezing Of Droplets With Immersed Mineral Dust Particles - Measurements And Parameterization, D. Niedermeier, S. Hartmann, R. A. Shaw, D. Covert, T. F. Mentel, J. Schneider, L. Poulain, P. Reitz, C. Spindler, T. Clauss, A. Kiselev, E. Hallbauer, H. Wex, K. Mildenberger, F. Stratmann
Michigan Tech Publications
During the measurement campaign FROST (FReezing Of duST), LACIS (Leipzig Aerosol Cloud Interaction Simulator) was used to investigate the immersion freezing behavior of size selected, coated and uncoated Arizona Test Dust (ATD) particles with a mobility diameter of 300 nm. Particles were coated with succinic acid (C4H6O4), sulfuric acid (H 2SO4) and ammonium sulfate ((NH4)) 2SO4). Ice fractions at mixed-phase cloud temperatures ranging from 233.15K to 239.15K (±0.60 K) were determined for all types of particles. In this temperature range, pure ATD particles and those coated with C4H6O4 or small amounts of H 2SO4 were found to be the most …
Monitoring Automotive Particulate Matter Emissions With Lidar: A Review, Claudio Mazzoleni, Hampden D. Kuhns, Hans Moosmüller
Monitoring Automotive Particulate Matter Emissions With Lidar: A Review, Claudio Mazzoleni, Hampden D. Kuhns, Hans Moosmüller
Michigan Tech Publications
Automotive particulate matter (PM) causes deleterious effects on health and visibility. Physical and chemical properties of PM also influence climate change. Roadside remote sensing of automotive emissions is a valuable option for assessing the contribution of individual vehicles to the total PM burden. LiDAR represents a unique approach that allows measuring PM emissions from in-use vehicles with high sensitivity. This publication reviews vehicle emission remote sensing measurements using ultraviolet LiDAR and transmissometer systems. The paper discusses the measurement theory and documents examples of how these techniques provide a unique perspective for exhaust emissions of individual and groups of vehicles.