Atmospheric Sciences Commons^™

First Observations Of Turbulence Generated By Grass Fires, Craig Clements, Shiyuan Zhong, Xindi Bian, Warren Heilman, Daewon Byun

Faculty Publications, Meteorology and Climate Science

Wildland fires radically modify the atmospheric boundary layer by inducing strong fire-atmosphere interactions. These interactions lead to intense turbulence production in and around the fire front. Two field experiments were conducted in tall-grass fuels to quantify turbulence generation during the passage of wind-driven fire fronts. Observations showed that the measured turbulence generated by the fires was five times greater than the turbulence in the ambient environment. The production of the turbulence at the surface near the fire front was caused by increased variance of the ambient wind, while the buoyancy was strongest at higher levels within the fire plume. Immediately …

Metcrax 2006 - Meteorological Experiments In Arizona's Meteor Crater, C. David Whiteman, Sebastian Hoch, Maura Hahnenberger, Andreas Muschinski, Vincent Hohreiter, Mario Behn, Yonghum Cheon, Sharon Zhong, Wenqing Yao, David Fritts, Craig Clements, Thomas Horst, William Brown, Steven Oncley

Faculty Publications, Meteorology and Climate Science

The Meteor Crater Experiment (METCRAX 2006) was conducted in October 2006 at Arizona's Meteor Crater to investigate stable boundary layer evolution in a topographically uncomplicated basin surrounded by the nearly homogeneous plain of the Colorado Plateau. The two goals of the experiment were 1) to investigate the microscale and mesoscale structure and evolution of the stable boundary layer in the crater and its surroundings and 2) to determine whether atmospheric seiches or standing waves are produced inside the crater. This article provides an overview of the scientific goals of the experiment; summarizes the research measurements, the crater topography, and the …

Sampling Of Malodorous Compounds In Air Using Stir Bar Sorbtive Extraction, John H. Loughrin, Nanh Lovanh, Arturo I. Quintanar, Rezaul Mahmood

High Plains Regional Climate Center: Staff Publications

Twisters, (poly)‐dimethylsiloxane‐coated magnetic stir bars, were used to measure compounds typical of swine manure malodor in air. In initial experiments, a time to achieve equilibrium was determined by preloading the stir bars with ten compounds with a range of volatilities and polarities and then monitoring their loss. The rate of loss was dependent on compound volatility, and the time for equilibrium to be attained varied widely, from 22 min for phenol to 210 min for skatole. To test whether the Twisters would respond linearly over a range of concentrations, the stir bars were placed in vented jars with solutions of …

Droughtscape, Winter 2008, Kelly Smith

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Now Up & On-Line:

Winter 2008 Outlook and Oct.-Dec. ’07 Summary

NDMC Experts Serve as Resource for Media

Drought Hits Ag and Urban Interests in 2007

Climatological Summary of Drought in 2007

NDMC Welcomes Data Miner Bo Zhang

New Grant Awards

Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Dimethylsulfide (DMS) atmospheric and oceanic concentrations and eddy covariance air/sea fluxes were measured over the N. Atlantic Ocean during July 2007 from Iceland to Woods Hole, MA, USA. Seawater DMS levels north of 55 degrees N ranged from 3 to 17 nM, with variability related to the satellite-derived distributions of coccoliths and to a lesser extent, chlorophyll. For the most intense bloom region southwest of Iceland, DMS air/sea fluxes were as high as 300 mu mol m(-2) d(-1), larger than current model estimates. The observations imply that gas exchange coefficients in this region are significantly greater than those estimated using …

Evaluation Of 1,3,5 Trimethylbenzene Degradation In The Detailed Tropospheric Chemistry Mechanism, Mcmv3.1, Using Environmental Chamber Data, A. Metzger, J. Dommen, J. Duplissy, A. S.H. Prevot, J. Kleffmann, Yasin F. Elshorbany, A. Wisthaler, U. Baltensperger

USF St. Petersburg Campus Faculty Publications

The degradation mechanism of 1,3,5-trimethyl-benzene (TMB) as implemented in the Master Chemical Mechanism version 3.1 (MCM) was evaluated using data from the environmental chamber at the Paul Scherrer Institute. The results show that the MCM provides a consistent description of the photo-oxidation of TMB/NO(x) mixtures for a range of conditions. In all cases the agreement between the measurement and the simulation decreases with decreasing VOC-NO(x) ratio and in addition with increasing precursor concentration. A significant underestimation of the decay rate of TMB and thus underestimation of reactivity in the system, consistent with results from previous appraisals of the MCM, was …

Characterization And Analysis Of Hailstorms In The Northern Great Plains, Thomas Sando

The Journal of Undergraduate Research

Hail is a meteorological occurrence that appears frequently during spring and summer across the Northern Great Plains. This paper first characterizes patterns associated with reported hail events occurring within a five-state region (North Dakota, Minnesota, South Dakota, Iowa, and Nebraska) from 2000-2006 using records taken from the National Climatic Data Center (NCDC) Severe Storms database. Patterns of interest include the seasonality of hail activity for each state and across the region, observational bias in the reporting of hailstone size, and temporal trends in the number of hail reports across the region and in each state. This paper then explores a …

The Identification And Verification Of Hazardous Convective Cells Over Oceans Using Visible And Infrared Satellite Observations, Michael F. Donovan, Earle R. Williams, Cathy Kessinger, Gary Blackburn, Paul H. Herzegh, Richard L. Bankert, Steve Miller, Frederick R. Mosher

Publications

Three algorithms based on geostationary visible and infrared (IR) observations are used to identify convective cells that do (or may) present a hazard to aviation over the oceans. The performance of these algorithms in detecting potentially hazardous cells is determined through verification with Tropical Rainfall Measuring Mission (TRMM) satellite observations of lightning and radar reflectivity, which provide internal information about the convective cells. The probability of detection of hazardous cells using the satellite algorithms can exceed 90% when lightning is used as a criterion for hazard, but the false-alarm ratio with all three algorithms is consistently large (40%), thereby exaggerating …

Technical Note: Molecular Characterization Of Aerosol-Derived Water Soluble Organic Carbon Using Ultrahigh Resolution Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, A. S. Wozniak, J. E. Bauer, R. L. Sleighter, R. M. Dickhut, Patrick Hatcher

Chemistry & Biochemistry Faculty Publications

Despite the acknowledged relevance of aerosol-derived water-soluble organic carbon (WSOC) to climate and biogeochemical cycling, characterization of aerosol WSOC has been limited. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) was utilized in this study to provide detailed molecular level characterization of the hi(,h molecular weight (HMW; m/z>223) component of aerosol-derived WSOC collected from rural sites in Virginia and New York, USA. More than 3000 peaks were detected by ESI FT-ICR MS within a m/z range of 223-600 for each sample. Approximately 86% (Virginia) and 78% (New York) of these peaks were assigned molecular formulas …

A Study Of Land Surface Processes Using Land Surface Models Over The Little River Experimental Watershed, A. K. Sahoo, P. A. Dirmeyer, P. R. Houser, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Three different land surface models (Hydrological improvements to the Simplified version of the Simple Biosphere model (HySSiB), Noah model, and Community Land Model (CLM)) were simulated on the NASA Goddard Space Flight Center’s Land Information System platform at 1-km resolution over the Little River Experimental Watershed, Georgia, and the simulated results were analyzed to address the local-scale land-atmosphere processes. All the three models simulated the soil moisture in space and time realistically. The Noah model produced higher soil moisture whereas the CLM got lower soil moisture with many dry down phases. CLM and HySSiB models were oversensitive to the atmospheric …

Contrasting The 2007 And 2005 Hurricane Seasons: Evidence Of Possible Impacts Of Saharan Dry Air And Dust On Tropical Cyclone Activity In The Atlantic Basin, D. Sun, K. M. Lau, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this study, we provide preliminary evidence of possible modulation by Saharan dust of hurricane genesis and intensification, by contrasting the 2007 and 2005 hurricane seasons. It is found that dust aerosol loadings over the Atlantic Ocean are much higher in 2007 than in 2005. The temperature difference between 2007 and 2005 shows warming in the low-middle troposphere (900–700 hPa) in the dusty region in the eastern North Atlantic, and cooling in the Main Development Region (MDR). The humidity (wind) differences between 2007 and 2005 indicate significant drying (subsidence) in the Western North Atlantic (WNA) in 2007. The drier air …

Forcing Mechanisms For Washoe Zephyr - A Daytime Downslope Wind Phenomenon In The Great Basin East Of The Sierra Nevada, Shiyuan Zhong, Ju Li, Craig Clements, Stephan Dewekker, Xindi Bian

Faculty Publications, Meteorology and Climate Science

This paper investigates the formation mechanisms for a local wind phenomenon known as Washoe Zephyr that occurs frequently in the lee of the Sierra Nevada. Unlike the typical thermally driven slope flows with upslope wind during daytime and downslope at night, the Washoe Zephyr winds blow down the lee slopes of the Sierra Nevada in the afternoon against the local pressure gradient. Long-term hourly surface wind data from several stations on the eastern slope of the Sierra Nevada and rawinsonde sounding data in the region are analyzed and numerical simulations are performed to test the suggested hypotheses on the formation …

Sublethal And Killing Effects Of Atmospheric-Pressure, Nonthermal Plasma On Eukaryotic Microalgae In Aqueous Media, Ying Zhong Tang, Xin Pei Lu, Mounir Laroussi, Fred C. Dobbs

OES Faculty Publications

In-depth studies on the interaction of nonthermal plasmas with microorganisms usually focus on bacteria; only little attention has been given to their effects on more complex eukaryotic cells. We report here nonthermal plasma's effects on cell motility, viability staining, and morphology of eukaryotic microalgae, with three marine dinoflagellates and a marine diatom as major targets. The effects on motility and viability staining depended on the time of exposure to plasma and the species of microalgae. We observed a strong pH decrease in aqueous samples (marine and freshwater algal cultures, their culture media, and deionized water) after exposure to plasma, and …