Oceanography and Atmospheric Sciences and Meteorology 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 …

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 …

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 …

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 …

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 …

Optical Estimation Of Auroral Ion Upflow: Theory, M. Zettergren, J. L. Semeter, P. L. Blelly, M. Diaz

Publications

This work presents a systematic analysis of optical emissions related to auroral ion upflow. Optical intensities and field‐aligned ion transport are computed for a set of monoenergetic incident electron beams using a combined fluid‐kinetic model. The kinetic portion models the energetic particle transport with a multiple stream approach and provides ionization, excitation, and heating rates to an eight‐moment fluid model of the ionosphere, which then calculates the resulting ion upflow. The analysis is used to develop a technique for estimating upward ion flux from photometric measurements at five discrete wavelengths: 427.8 nm, 557.7 nm, 630.0 nm, 732 nm, and 844.6 …

Validation Of The Aura Microwave Limb Sounder Hnomeasurements, M L. Santee, A Lambert, W G. Read, N J. Livesey, R E. Cofield, D T. Cuddy, W H. Daffer, B J. Drouin, L Froidevaux, R A. Fuller, R F. Jarnot, B W. Knosp, G L. Manney, V S. Perun, W V. Snyder, P C. Stek, R P. Thurstans, P A. Wagner, J W. Waters, G Muscari, R L. De Zafra, Jack E. Dibb, D W. Fahey, P J. Popp, T P. Marcy, K W. Jucks, G C. Toon, R A. Stachnik, P F. Bernath, C D. Boone, K A. Walker, J Urban, D Murtagh

Earth Sciences

We assess the quality of the version 2.2 (v2.2) HNO₃ measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS HNO₃ product has been greatly improved over that in the previous version (v1.5), with smoother profiles, much more realistic behavior at the lowest retrieval levels, and correction of a high bias caused by an error in one of the spectroscopy files used in v1.5 processing. The v2.2 HNO₃ data are scientifically useful over the range 215 to 3.2 hPa, with single-profile precision of ∼0.7 ppbv throughout. Vertical resolution is 3–4 km …

Total Depletion Of Hg° In The Upper Troposphere-Lower Stratosphere, R. Talbot, Huiting Mao, Jack E. Dibb, M A. Avery

Earth Sciences

Our current understanding of atmospheric mercury lacks fundamental details. Gas phase elemental mercury (Hg°) was measured aboard the NASA DC-8 research aircraft during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B) conducted in spring 2006 over the North Pacific. Our data confirm efficient chemical cycling of Hg° in the tropopause region and show that it is strongly anti-correlated with O₃ there, yielding a tropospheric-stratospheric mixing curve of ∼−0.20 ppqv Hg°/ppbv O₃. In addition, we found frequent total depletion of Hg° in upper tropospheric (8–12 km) air masses impacted by stratospheric influence. When O₃ mixing ratios were >300 …

Diagnosis Of The July 6, 2002 Ogallala, Nebraska Flash Flood, David B. Radell, Mark R. Anderson, John W. Stoppkotte, James R. Mccormick

Department of Earth and Atmospheric Sciences: Faculty Publications

During the early morning hours of 6 July 2002, a mesoscale convective system (MCS) traversed southwestern Nebraska and produced more than 40 cm of precipitation, resulting in a flash flood that closed Interstate 80 and caused one fatality near Ogallala, Nebraska. Regional climatology yields that this flash flood ranked first in precipitation amount for a 24 hour period over the past one hundred years. Synoptic and mesoscale features similar to other flash flooding events and conducive to extremely heavy precipitation were in place over the Central Plains, including a weak upper level ridge, high precipitable water values (180% of normal), …

A Summer Time Series Of Particulate Carbon In The Air And Snow At Summit, Greenland, Gayle S.W. Hagler, M Bergin, Eugene A. Smith, Jack E. Dibb

Earth Sciences

Carbonaceous particulate matter is ubiquitous in the lower atmosphere, produced by natural and anthropogenic sources and transported to distant regions, including the pristine and climate-sensitive Greenland Ice Sheet. During the summer of 2006, ambient particulate carbonaceous compounds were characterized on the Greenland Ice Sheet, including the measurement of particulate organic (OC) and elemental (EC) carbon, particulate water-soluble organic carbon (WSOC), particulate absorption coefficient (σ_ap), and particle size-resolved number concentration (PM_0.1–1.0). Additionally, parallel ∼50-day time series of water-soluble organic carbon (WSOC), water-insoluble organic carbon (WIOC), and elemental carbon (EC) were quantified at time increments of 4–24 …

A Statistical Model To Forecast Short-Term Atlantic Hurricane Intensity, Kevin Law, Jay S. Hobgood

Geography Faculty Research

An alternative 24-h statistical hurricane intensity model is presented and verified for 13 hurricanes during the 2004–05 seasons. The model uses a new method involving a discriminant function analysis (DFA) to select from a collection of multiple regression equations. These equations were developed to predict the future 24-h wind speed increase and the 24-h pressure drop that were constructed from a dataset of 103 hurricanes from 1988 to 2003 that utilized 25 predictors of rapid intensification. The accuracy of the 24-h wind speed increase models was tested and compared with the official National Hurricane Center (NHC) 24-h intensity forecasts, which …

Seasonal And Diel Variation Of Atmospheric Mercury Concentrations In The Reno (Nevada, Usa) Airshed, Jelena Stamenkovic, Seth Lyman, Mae S. Gustin

USU Uintah Basin Faculty Publications

This paper describes total gaseous mercury (TGM) concentrations measured in Reno, Nevada from 2002 to 2005. The 3-year mean and median air Hg concentrations were 2.3 and 2.1 ng m−3, respectively. Mercury concentrations exhibited seasonality, with the highest concentrations in winter, and the lowest in summer and fall. A well-defined diel pattern in TGM concentration was observed, with maximum daily concentrations observed in the morning and minimum in the afternoon. A gradual increase of TGM concentration was observed in the evening and over night. The early morning increase in TGM was likely due to activation of local surface emission sources …

Droughtscape, Fall 2007, National Drought Mitigation Center

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

Fall 2007 Outlook

Diverse Impacts Reported in Summer of 2007

Decadal Climate Cycles Hold Predictive Potential

Drought Experts Take Roadmap to Congress

NDMC Research Updates

Particulate And Water-Soluble Carbon Measured In Recent Snow At Summit, Greenland, Gayle S.W. Hagler, M Bergin, Eugene A. Smith, Jack E. Dibb, Casey Anderson, Eric J. Steig

Earth Sciences

Water-soluble organic carbon (WSOC), waterinsoluble particulate organic carbon (WIOC), and particulate elemental carbon (EC) were measured simultaneously for the first time on the Greenland Ice Sheet in surface snow and in a 3-meter snow pit. Snow pit concentrations reveal that, on average, WSOC makes up the majority (89%) of carbonaceous species, followed by WIOC (10%) and EC (1%). The enhancement of OC relative to EC (ratio 99:1) in Greenland snow suggests that, along with atmospheric particulate matter, gaseous organics contribute to snow-phase OC. Comparison of summer surface snow concentrations in 2006 with past summer snow pit layers (2002 – 2005) …

Impact Of Multiscale Dynamical Processes And Mixing On The Chemical Composition Of The Upper Troposphere And Lower Stratosphere During The Intercontinental Chemical Transport Experiment–North America, T D. Fairlie, Melody A. Avery, R B. Pierce, J Al-Saadi, Jack E. Dibb, G W. Sachse

Earth Sciences

We use high-frequency in situ observations made from the DC8 to examine fine-scale tracer structure and correlations observed in the upper troposphere and lower stratosphere during INTEX-NA. Two flights of the NASA DC-8 are compared and contrasted. Chemical data from the DC-8 flight on 18 July show evidence for interleaving and mixing of polluted and stratospheric air masses in the vicinity of the subtropical jet in the upper troposphere, while on 2 August the DC-8 flew through a polluted upper troposphere and a lowermost stratosphere that showed evidence of an intrusion of polluted air. We compare data from both flights …

An Overview Of Snow Photochemistry: Evidence, Mechanisms And Impacts, A M. Grannas, A E. Jones, Jack E. Dibb, M Ammann, Cort Anastasio, H J. Beine, M Bergin, J Bottenheim, C S. Boxe, G Carver, G Chen, J H. Crawford, Florent Domine, M M. Frey, M I. Guzman, D E. Heard, D Helmig, M R. Hoffmann, R E. Honrath, L Gregory Huey, Manuel Hutterli, H W. Jacobi, P Klan, Barry Lefer, J Mcconnell, J Plane, R Sander, J Savarino, P B. Shepson, W R. Simpson, J R. Sodeau, R Von Glasow, R Weller, E W. Wolff, T Zhu

Earth Sciences

It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to …

Mesosphere And Lower Thermosphere Neutral Winds Observations Using Rocket-Released Chemical Trails At Poker Flat, Alaska, Tianyu Zhan

All Dissertations

Sounding rocket campaigns ARIA I through ARIA IV, CODA 2, HEX 1, JOULE 1 and JOULE 2 all carried out at Poker Flat Research Range at Alaska, covering the geomagnetic condition from quiet to highly disturbed. Trimethyl aluminum (TMA) were released during the rocket flights to study the mesosphere and lower thermosphere neutral wind at high-latitude region. The results of horizontal neutral wind profiles are presented. The comparison shows that under disturbed condition the wind velocity is stronger and the jet feature at the bottom side of wind maximum with unstable wind shear is lifted to a higher altitude. Under …

Multimodel Projections Of Stratospheric Ozone In The 21st Century, V. Eyring, D. W. Waugh, G. E. Bodeker, Eugene C. Cordero, H. Akiyoshi, J. Austin, S. R. Beagley, B. A. Boville, P. Braesicke, C. Brühl, N. Butchart, M. P. Chipperfield, M. Dameris, R. Deckert, M. Deushi, S. M. Frith, R. R. Garcia, A. Gettelman, M. A. Giorgetta, D. E. Kinnison, E. Mancini, E. Manzini, D. R. Marsh, S. Matthes, T. Nagashima, P. A. Newman, J. E. Nielsen, S. Pawson, G. Pitari, D. A. Plummer, E. Rozanov, M. Schraner, J. F. Scinocca, K. Semeniuk, T. G. Shepherd, K. Shibata, B. Steil, R. S. Stolarski, W. Tian, M. Yoshiki

Faculty Publications, Meteorology and Climate Science

[1] Simulations from eleven coupled chemistry-climate models (CCMs) employing nearly identical forcings have been used to project the evolution of stratospheric ozone throughout the 21st century. The model-to-model agreement in projected temperature trends is good, and all CCMs predict continued, global mean cooling of the stratosphere over the next 5 decades, increasing from around 0.25 K/decade at 50 hPa to around 1 K/decade at 1 hPa under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario. In general, the simulated ozone evolution is mainly determined by decreases in halogen concentrations and continued cooling of …

Droughtscape, Summer 2007, National Drought Mitigation Center

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

Summer 07 Outlook

Hayes Named Director of NDMC

NDMC & UN Plan for Drought

Book Review: The Worst Hard Time

Drought Tools Workshops Underway

U.S. Drought Monitor Forum October 10-11, 2007 Portland, Oregon

Climate. Stern Review: The Economics Of Climate Change, Nicholas Stern

New England Journal of Public Policy

This chapter examines the increasingly serious impacts on people as the world warms. Climate change is a serious and urgent issue. The Earth has already warmed by 0.7°C since around 1900 and is committed to further warming over coming decades simply due to past emissions. On current trends, average global temperatures could rise by 2–3°C within the next fifty years or so, with several degrees more in the pipeline by the end of the century if emissions continue to grow. This chapter examines how the physical changes in climate . . . affect the essential components of lives and livelihoods …

Climate. Scrubbing The Sky: Climate Change And The Productive Center, Marcy Murninghan

New England Journal of Public Policy

This article sketches out the efforts of government, business, and civil society to address the problem of climate change. It identifies some of the key initiatives underway — including proposals for more stringent caps on greenhouse gas (GHG) emissions; the creation of a market-based trading system that provides incentives and profits for entities that reduce their GHG emission levels; more robust research and development of alternative energy sources as well as new approaches to traditional ones; and continued public education — and portrays the bipartisan, collaborative, multilateral nature of saving Mother Nature. While acknowledging that ultimately these efforts may be …

A Global Mhd Simulation Of An Event With A Quasi-Steady Northward Imf Component, V G. Merkin, J G. Lyon, B J. Anderson, H Korth, C C. Goodrich, K Papadopoulos

Dartmouth Scholarship

We show results of the Lyon-Fedder-Mobarry (LFM) global MHD simulations of an event previously ex- amined using Iridium spacecraft observations as well as DMSP and IMAGE FUV data. The event is chosen for the steady northward IMF sustained over a three-hour pe- riod during 16 July 2000. The Iridium observations showed very weak or absent Region 2 currents in the ionosphere, which makes the event favorable for global MHD model- ing. Here we are interested in examining the model’s per- formace during weak magnetospheric forcing, in particular, its ability to reproduce gross signatures of the ionospheric currents and convection pattern …