A5070548326- Atmospheric aerosols and clouds
- Lightning and Electromagnetic Phenomena
- Meteorological Phenomena and Simulations
- Atmospheric chemistry and aerosols
- Fire effects on ecosystems
- Icing and De-icing Technologies
- Precipitation Measurement and Analysis
- Wind and Air Flow Studies
- Advanced Aircraft Design and Technologies
- Thermal Analysis in Power Transmission
- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
- Thermal Radiation and Cooling Technologies
- Aeolian processes and effects
- Earthquake Detection and Analysis
- Plant Water Relations and Carbon Dynamics
- Atmospheric and Environmental Gas Dynamics
- Air Traffic Management and Optimization
- Wind Energy Research and Development
- Cryospheric studies and observations
- Water Treatment and Disinfection
- Solar Radiation and Photovoltaics
- Power Line Communications and Noise
- Electrical Fault Detection and Protection
- Aerosol Filtration and Electrostatic Precipitation
University of North Dakota
2020-2023
South Dakota School of Mines and Technology
2007-2020
University at Albany, State University of New York
1978-2012
Goddard Space Flight Center
2005
Caelum Research Corporation (United States)
2005
Colorado State University
2004
NSF National Center for Atmospheric Research
2004
NOAA National Weather Service
2004
NOAA National Severe Storms Laboratory
2004
New Mexico Institute of Mining and Technology
2004
During May–July 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) occurred in High Plains, near Colorado–Kansas border. STEPS aimed to achieve a better understanding of interactions between kinematics, precipitation, electrification severe thunderstorms. Specific scientific objectives included 1) apparent major differences precipitation output from supercells that have led them being classified as low (LP), classic or medium high precipitation; 2) lightning...
Abstract In situ observations of cloud properties made by airborne probes play a critical role in ice research through their process studies, parameterization development, and evaluation simulations remote sensing retrievals. To determine how vary with environmental conditions, data collected during different field projects processed groups must be used. However, because the diverse algorithms codes that are used to measurements, it can challenging compare results. Therefore is vital...
Abstract In Part I of this two-part paper, a formulation was developed to treat fragmentation in ice–ice collisions. the present II, is implemented two microphysically advanced cloud models simulating convective line observed over U.S. high plains. One model 2D with spectral bin microphysics scheme. The other has hybrid bin–two-moment bulk scheme 3D. case consists cumulonimbus cells cold bases (near 0°C) dry troposphere. Only breakup included simulation are aircraft observations particles...
The relationships among kinematic, microphysical, and electric field properties within a multicell Florida thunderstorm are investigated using observations from three Doppler radars (one with multiple wavelength polarization diversity capabilities), four instrumented penetrating aircraft, surface-based mill network, other observation facilities. storm was convectively active for about 1 h at least five primary cells developed the during this time, one of which went through consecutive...
Abstract Recommendations are presented for in situ and remote sensing instruments capabilities needed to advance the study of convection turbulence atmosphere. These recommendations emerged from a community workshop held on 22–24 May 2017 at National Center Atmospheric Research sponsored by Science Foundation. Four areas research were distinguished this workshop: i) boundary layer flows, including convective stable layers over heterogeneous land use terrain conditions; ii) dynamics...
Abstract Hail and graupel are linked to lightning production important components of cloud evolution. can also cause significant damage when it precipitates the surface. The accurate prediction amount location hail effects on other hydrometeor species depends upon size distribution assumed. Here, we use ~310 km in situ observations from flights South Dakota School Mines Technology T-28 storm-penetrating aircraft constrain representation particle (PSD) hail. maximum ~1-km water content...
Abstract In this two-part paper, influences from environmental factors on lightning in a convective storm are assessed with model. Part I, an electrical component is described and applied the Aerosol–Cloud model (AC). AC treats many types of secondary (e.g., breakup ice–ice collisions, raindrop-freezing fragmentation, rime splintering) primary (heterogeneous, homogeneous freezing) ice initiation. represents flashes statistical treatment branching fractal law constrained by video imagery. The...
Abstract Use of dual-wavelength radar, with properly chosen wavelengths, will significantly lessen the ambiguities in retrieval microphysical properties hydrometeors. In this paper, a algorithm is described to estimate characteristic parameters snow size distributions. An analysis computational results, made at X and Ka bands (T-39 airborne radar) S (CP-2 ground-based radar), indicates that valid estimates median volume diameter particles, D0, should be possible if one two wavelengths radar...
The important microphysical relationships determining the radiative properties and growth of ice crystals in stratiform cirrus clouds are investigated. A horizontally infinite cloud layer is modeled midlatitude upper troposphere. Optical spheres equal surface area assumed to represent scattering characteristics nonspherical crystals, while delta-Eddington approximation used solve transfer equations. Classical expressions for particle sublimation coupled those energy exchange order follow...
Clear-air seeding is the artificial creation or enhancement of cloud cover in clear air which between saturation with respect to ice and liquid water. Previous work has demonstrated that clear-air possible, may be economically worthwhile through its effects on radiation balance near ground. Order-of-magnitude arguments, contrail observations direct measurements are used assess frequency horizontal extent opportunities for upper troposphere. Clear, ice-supersaturated a common occurrence...
Various procedures for inferring hydrometeor characteristics from polarimetric radar data have indicated that regions with echoes exhibiting relatively high linear depolarization ratios along low differential reflectivity contain wet graupel or hail. Such particles could be found either in a melting zone below the 0°C level cloud region of growth where rate supercooled water accretion overwhelms at which latent heat associated complete freezing can dissipated. In subtropical clouds such as...
The North Dakota Thunderstorm Project was conducted in the Bismarck, Dakota, area from 12 June through 22 July 1989. project deployed Doppler radars, cloud physics aircraft, and supporting instrumentation to study a variety of aspects convective clouds. These included transport dispersion; entrainment; cloud-ice initiation evolution; storm structure, dynamics, kinematics; atmospheric chemistry; electrification. Of primary interest were tracer experiments that identified tracked specific...
Precipitation development and electrification in Florida thunderstorms are observed using an instrumented aircraft a multiparameter radar. A low concentration of raindrops initially develops the updraft, these begin to freeze when they carried above 0°C level. High concentrations ice particles downdrafts soon appear −5° −10°C regions cloud, where penetrated, as do electric fields range tens kilovolts per meter. In cell with relatively weak updrafts, drops start at temperatures just below...
This study deals with the microphysical and electrical evolution of a thunderstorm that occurred on August 9, 1991, during Convection Precipitation/Electrification (CaPE) Experiment in eastern Florida. During its approximately 1‐hour lifetime, storm was penetrated several times by Institute Atmospheric Sciences' T‐28 aircraft at midlevels. It also low middle‐levels National Oceanographic Administration (NOAA) P‐3 scanned three radars, one which had multiparameter capabilities, operated...
This analysis combines vertical electric field components E z observed by two research aircraft flying horizontally at levels, with soundings of thermodynamic parameters and made five balloons, to produce a quasi‐three‐dimensional view the space charge distribution in trailing stratiform cloud region behind mesoscale convective system (MCS) that developed central Oklahoma late afternoon 2 June 1991. The balloons were launched serially one‐hour intervals from sites separated 80 km along...
Data from flights by the South Dakota School of Mines and Technology’s North American T-28 storm-penetrating aircraft during nine different research projects conducted between 1991 2003 are analyzed. These flights, usually flown summer months in central high plains United States, targeted regions convective storms containing vigorous updrafts, downdrafts, precipitation, including hail. Observations indicate that three most hazardous components flying summertime deep clouds icing, turbulence...
Abstract Daily observations of cloud condensation nuclei (CCN) were made for three summer months in 2005 at a site rural western North Dakota. The goal was to define the natural background CCN population characteristics and lay groundwork investigating potential impact intentionally modifying clouds this region using hygroscopic cloud-seeding techniques. Concentrations active ∼0.5% supersaturation, averaged over several midday hours on each day, ranged from less than 200 more 1700 cm−3. This...
Comparisons are made between liquid water concentration (LWC) readings obtained from a Johnson–Williams (J–W) cloud meter and King (Commonwealth Scientific Industrial Research Organisation) probe, both mounted on the armored T-28 research aircraft during penetrations of springtime convective storms in Oklahoma Colorado. The probe almost always higher, being up to twice those J–W instrument clouds with narrower droplet spectra. In broader spectra, ratio often climbs three or greater. responds...
This paper presents new results from studies of aircraft-produced ice particles (APIPs) in supercooled fog and clouds. Nine aircraft, including a Beech King Air 200T cloud physics Piper Aztec, Cessna 421-C, two North American T-28s, an Aero Commander, Navajo, Turbo Baron, second four-bladed were involved the tests. The instrumented served as monitoring aircraft for trails created, or not when other flown through clouds at various temperatures both test it itself was tested. In some cases...
Investigation of charges on particles in thunderstorms was conducted during the Severe Thunderstorm Electrification and Precipitation Study. In case presented here, aircraft measurements electric field, hydrometeor size charge, were made a precipitation shaft beneath base small convective cloud which electrified, but produced no lightning. A newly designed instrument used to obtain particle image charge for larger than 0.2 mm size. Laboratory tests calculations suggest that under optimum...
The ice saturation ratio at which 1% of aged silver iodide and lead aerosol particles nucleate from moist air is observed to depend on temperature. Between roughly −30 −67°C the threshold for both types rises slowly with decreasing temperature in agreement a simple classical nucleation theory. −6 −30°C more rapidly than predicted by theory while decreases.
An armored T-28 research aircraft made direct observations of the hydrometeors present at approximately −3°C temperature level in inflow region a multicell thunderstorm. During penetration, both Colorado State University (CSU)–University Chicago and Illinois Water Survey (CHILL) 11-cm-wavelength dual-polarization radar Denver, Colorado, Front Range Airport (KFTG) Weather Surveillance Radar-1988 Doppler (WSR-88D) were scanning this storm. Polarimetric indications hail (high reflectivity low...