A5084266905- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Air Quality and Health Impacts
- Atmospheric Ozone and Climate
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Vehicle emissions and performance
- Advanced Thermodynamic Systems and Engines
- Spectroscopy and Laser Applications
- Fire effects on ecosystems
- Advanced Aircraft Design and Technologies
- Meteorological Phenomena and Simulations
- Thermal Radiation and Cooling Technologies
- Refrigeration and Air Conditioning Technologies
- Spacecraft and Cryogenic Technologies
- Advanced Thermodynamics and Statistical Mechanics
- Cryospheric studies and observations
- Calibration and Measurement Techniques
- Aeolian processes and effects
- Combustion and flame dynamics
- Acoustic Wave Phenomena Research
- Thermodynamic and Exergetic Analyses of Power and Cooling Systems
- Icing and De-icing Technologies
- Thermography and Photoacoustic Techniques
- Underwater Acoustics Research
University of Nevada, Reno
2015-2024
University of Ottawa
2023
Desert Research Institute
2005-2019
Nevada System of Higher Education
2004-2019
Rocky Mountain Research Station
2007
University of Utah
1998-2004
University of Mississippi
1990-2002
Acoustical Society of America
2000
NSF National Center for Atmospheric Research
1998
Naval Postgraduate School
1993
Charring of organic carbon (OC) during thermal/optical analysis is monitored by the change in a laser signal either reflected from or transmitted through filter punch. Elemental (EC) suspended particulate matter collected on quartz-fiber filters defined as that evolves after detected optical attains value it had prior to commencement heating, with rest classified (OC). Heretofore, operational definitions EC were believed be caused different temperature protocols rather than method monitoring...
Two extreme cases of aerosol optics from the Reno Aerosol Optics Experiment are used to develop a model-based calibration scheme for 7-wavelength aethalometer. The include those very white and dark samples. former allows an assessment scattering offset associated with this filter-based method, wavelength-dependent measured 3-wavelength nephelometer, interpolated extrapolated 7 wavelengths A photoacoustic instrument operating at 532 nm is evaluate filter loading effect caused by light...
Abstract. Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at T0 urban supersite Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. concentrations, diurnal cycles, size distributions of inorganic organic species are similar to results from CENICA April 2003 (OA) comprising about half fine PM mass. Positive Matrix Factorization (PMF) analysis high resolution OA spectra identified three major...
Abstract. We report the direct observation of laboratory production spherical, carbonaceous particles – "tar balls" from smoldering combustion two commonly occurring dry mid-latitude fuels. Real-time measurements spectrally varying absorption Ångström coefficients (AAC) indicate that a class light absorbing organic carbon (OC) with wavelength dependent imaginary part its refractive index optically defined as "brown carbon" is an important component tar balls. The spectrum parts their complex...
A dual‐wavelength photoacoustic instrument operating at 405 and 870 nm was used during the 2006 Fire Lab Missoula Experiment to measure light scattering absorption by smoke from combustion of a variety biomass fuels. Simultaneous measurements aerosol reciprocal nephelometry within instrument's acoustic resonator accompany measurements. Single albedo values ranging 0.37 0.95 were measured for different fuel types, spectral dependence quantified using Ångström exponent absorption. An near...
Abstract. Spectral aerosol light absorption is an important parameter for the assessment of radiation budget atmosphere. Although on-line measurement techniques absorption, such as Aethalometer and Particle Soot Absorption Photometer (PSAP), have been available two decades, they are limited in accuracy spectral resolution because need to deposit on a filter substrate before measurement. Recently, 7-wavelength (λ) became commercially available, which covers visible (VIS) near-infrared (NIR)...
Inter-comparison studies of well-characterized fractal soot particles were conducted using the following four instruments: Aerosol Mass Spectrometer-Scanning Mobility Particle Sizer (AMS-SMPS), Single Soot Photometer (SP2), Multi-Angle Absorption (MAAP), and Photoacoustic Spectrometer (PAS). These instruments provided measurements refractory mass incandescent (SP2) optically absorbing (MAAP PAS). The studied in mobility diameter range from 150 nm to 460 generated by controlled flames with...
Abstract. The concept of wavelength-dependent absorption Ångström coefficients (AACs) is discussed and clarified for both single two-wavelengths AACs guidance their implementation with noisy spectra provided. This discussion followed by application the to models brown carbon bulk including damped simple harmonic oscillator model, its Lorentzian approximation, band-gap model without Urbach tail. We show that tail always has an unphysical discontinuity in first derivative AAC at – Urbach-tail...
Abstract. A comparison between observed aerosol optical properties from the MILAGRO field campaign, which took place in Mexico City Metropolitan Area (MCMA) during March 2006, and values simulated by Weather Research Forecasting (WRF-Chem) model, reveals large differences. To help identify source of discrepancies, data campaign are used to evaluate "aerosol chemical properties" module implemented full chemistry version WRF-Chem model. The evaluation uses measurements size distributions...
A new multiangle absorption photometer for the measurement of aerosol light was recently introduced that builds on simultaneous radiation transmitted through and scattered back from a particle-loaded fiber filter at multiple detection angles. The coefficient filter-deposited is calculated optical properties entire system, which are determined by two-stream-approximation radiative transfer scheme. In course Reno Aerosol Optics Study (RAOS), response characteristics photometry (MAAP) white...
A filter-based single-wavelength photometer (Particle Soot Absorption Photometer, PSAP) for measuring light absorption by aerosols was modified to measure at three wavelengths, 467 nm, 530 and 660 nm. The an unmodified were calibrated during the Reno Aerosol Optics Study (RAOS) 2002 against two standards: a photoacoustic instrument difference between extinction scattering coefficient. This method has be corrected aerosol transmission changes. simple function this derived from calibration...
Values for Mie‐equivalent aerosol asymmetry parameter ( g ) were derived using a variety of methods from the large suite measurements (in situ and remote surface aircraft) made in Oklahoma during 2003 Intensive Operations Period (IOP). Median values dry at 550 nm ranged between 0.55 0.63 over all instruments derivation methods, with exception one instrument which did not measure full size range optically important aerosol. “wet” (i.e., humidity conditions closer to ambient) 0.59 0.72....
The Reno Aerosol Optics Study (RAOS) was designed and conducted to compare the performance of many existing new instruments for in situ measurement aerosol optical properties with a focus on determination light absorption. For this study, simple test aerosols black white particles were generated combined external mixtures under low relative humidity conditions delivered each system. mixing delivery system constantly monitored using particle counters nephelometers ensure that same number...
Abstract. Hundreds of wildfires in Northern California were sparked by lightning during the summer 2008, resulting downwind smoke for months June and July. Comparisons are reported aerosol optics measurements Reno, Nevada made very smoky month July relatively clean August. Photoacoustic instruments equipped with integrating nephelometers used to measure light scattering absorption coefficients at wavelengths 405 nm 870 nm, revealing a strong variation wavelength. Insight on fuels burned is...
The morphology of particles emitted by wildland fires contributes to their physical and chemical properties but is rarely determined. As part a study at the USFS Fire Sciences Laboratory (FSL) investigating particulate matter fires, we studied size, morphology, microstructure from combustion eight different fuels (i.e., sagebrush, poplar wood, ponderosa pine needles, white tundra cores, two grasses) scanning electron microscopy. Six these were dry, while fuels, namely cores one grasses, had...
Emission measurements were obtained for a variety of military vehicles at Hill Air Force Base (Ogden, UT) in November 2000 as part Strategic Environmental Research and Development Program. Aircraft ground support equipment using gasoline, diesel, JP8 fuels tested chassis dynamometers under predetermined load. The exhaust from the vehicle was passed to dilution tunnel where it diluted 30−40 times collected Micro-Orifice Uniform Deposit Impactor (MOUDI) fitted with aluminum substrates, an...
Ambient measurements are reported of aerosol light absorption from photoacoustic and filter‐based instruments (aethalometer a particle soot photometer (PSAP)) to provide insight on the measurement science. Measurements were obtained during Big Bend Regional Aerosol Visibility Observational Study at National Park in South Texas. The aethalometer black carbon concentration this site correlate reasonably well with absorption, slope 8.1 m 2 /g small offset. Light never exceeded 2.1 Mm −1 month...
Combustion of wildland fuels represents a major source particulate matter (PM) and light-absorbing elemental carbon (EC) on national global scale, but the emission factors profiles have not been well characterized with respect to different combustion phases. These uncertainties limit accuracy current inventories, smoke forecasts, apportionments. This study investigates evolution gaseous efficiency by burning in laboratory facility. Emission for dioxide (CO2), monoxide (CO), total hydrocarbon...
Abstract. Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at T0 urban supersite Mexico City with a High-Resolution Aerosol Mass Spectrometer (AMS) and complementary instrumentation. Positive Matrix Factorization (PMF) of high resolution AMS spectra identified biomass burning organic (BBOA) component, which includes several large plumes that appear to be from forest fires within region. Here, we show BBOA concentration correlates fire counts vicinity most...
During the Fire Laboratory at Missoula Experiments (FLAME), we studied physical, chemical, and optical properties of biomass burning smoke from laboratory combustion various wildland fuels. A good understanding these is important in determining radiative effects aerosols, with impacts on both local regional visibility global climate. We measured aerosol size distributions two instruments: a differential mobility particle sizer (DMPS) an counter (OPC). Volume different burns varied monomodal...
Theoretical treatments of thermoacoustics have been reported for stacks with circular pore and parallel plate geometries. A general linear formulation is developed gas-filled thermoacoustic elements such as heat exchangers, stacks, tubes having pores arbitrary cross-sectional geometry. For compactness in the following, F represents functional form transverse variation longitudinal particle velocity. Generally, a function frequency, geometry, response functions transport coefficients gas...
Sign and magnitude of solar aerosol direct radiative forcing are largely determined by the single scattering albedo ( SSA ) underlying scene (e.g., surface albedo). On a global scale, mineral dust has largest mass emission rate, average column burden, optical depth all types. Therefore, better understanding its properties with focus on is great importance. Here, we entrain ten bulk soil samples from deserts semi‐arid regions in Arabian Peninsula, locations representative Sahara Sahel North...