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Articles 1771 - 1800 of 2462

Full-Text Articles in Atmospheric Sciences

Characteristics Of Tropospheric Ozone Depletion Events In The Arctic Spring: Analysis Of The Arctas, Arcpac, And Arcions Measurements And Satellite Bro Observations, T P. Kurosu, Yuhang Wang, T P. Kurosu, K Chance, A Rozanov, A Richter, S J. Oltmans, A M. Thompson, Jonathan Hair, Marta Fenn, Andrew Weinheimer, Thomas B. Ryerson, S Solberg, L Gregory Huey, J Liao, Jack E. Dibb, J A. Neuman, J Nowak, B Pierce, M Natarajan, J Al-Saadi Oct 2012

Characteristics Of Tropospheric Ozone Depletion Events In The Arctic Spring: Analysis Of The Arctas, Arcpac, And Arcions Measurements And Satellite Bro Observations, T P. Kurosu, Yuhang Wang, T P. Kurosu, K Chance, A Rozanov, A Richter, S J. Oltmans, A M. Thompson, Jonathan Hair, Marta Fenn, Andrew Weinheimer, Thomas B. Ryerson, S Solberg, L Gregory Huey, J Liao, Jack E. Dibb, J A. Neuman, J Nowak, B Pierce, M Natarajan, J Al-Saadi

Earth Sciences

Arctic ozone depletion events (ODEs) are caused by halogen catalyzed ozone loss. In situ chemistry, advection of ozone-poor air mass, and vertical mixing in the lower troposphere are important factors affecting ODEs. To better characterize the ODEs, we analyze the combined set of surface, ozonesonde, and aircraft in situ measurements of ozone and bromine compounds during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS), the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC), and the Arctic Intensive Ozonesonde Network Study (ARCIONS) experiments (April 2008). Tropospheric BrO columns retrieved from satellite measurements and back …


Electron Loss And Meteoric Dust In The Mesosphere, M. Friedrich, M. Rapp, T. Blix, U. P. Hoppe, K. Torkar, S. Robertson, S. Dickson, Kristina Lynch Oct 2012

Electron Loss And Meteoric Dust In The Mesosphere, M. Friedrich, M. Rapp, T. Blix, U. P. Hoppe, K. Torkar, S. Robertson, S. Dickson, Kristina Lynch

Dartmouth Scholarship

No abstract provided.


Droughtscape, Fall 2012, National Drought Mitigation Center Oct 2012

Droughtscape, Fall 2012, National Drought Mitigation Center

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

Contents

Director’s report

Updated resources

Drought outlook and review

2012 and past droughters

Summer impacts summary

Urban planners and drought

USDM wins CLEAN seal

Meixiu Yu's Chinese SPEI

Ethiopian project

Mexican VegDRI

Drought monitor sculpture


Investigation Of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy, Christopher A. Rice Sep 2012

Investigation Of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy, Christopher A. Rice

Theses and Dissertations

A field deployable, tunable diode laser absorption spectroscopy (TDLAS) device fiber coupled to a pair of 12.5" Ritchey-Chretien telescopes was used to study atmospheric propagation for open path lengths of 100 m to 1,000 m to estimate atmospheric transmission at key High Energy Laser (HEL) wavelengths. The potassium (K) version of the Diode Pumped Alkali Laser (DPAL) operates in between two of the sharp oxygen rotational features in the PP and the PQ branches. Initial experiments were performed in the vicinity of molecular oxygen X3Σ-g to b1Σ+g electronic transition lines near the potassium emission line at 770 nm. More than …


Retrieval Of Sub-Pixel-Based Fire Intensity And Its Application For Characterizing Smoke Injection Heights And Fire Weather In North America, David Peterson Sep 2012

Retrieval Of Sub-Pixel-Based Fire Intensity And Its Application For Characterizing Smoke Injection Heights And Fire Weather In North America, David Peterson

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

For over two decades, satellite sensors have provided the locations of global fire activity with ever-increasing accuracy. However, the ability to measure fire intensity, know as fire radiative power (FRP), and its potential relationships to meteorology and smoke plume injection heights, are currently limited by the pixel resolution. This dissertation describes the development of a new, sub-pixel-based FRP calculation (FRPf) for fire pixels detected by the MODerate Resolution Imaging Spectroradiometer (MODIS) fire detection algorithm (Collection 5), which is subsequently applied to several large wildfire events in North America. The methodology inherits an earlier bi-spectral algorithm for retrieving sub-pixel …


Coastal Hurricane Damage Assessment Via Wavelet Transform Of Remotely Sensed Imagery, Ricky Carl Crowsey Aug 2012

Coastal Hurricane Damage Assessment Via Wavelet Transform Of Remotely Sensed Imagery, Ricky Carl Crowsey

Dissertations

This dissertation uses post storm imagery processed using wavelet transforms to investigate the capability of wavelet transform-based methods to classify post storm damage of residential areas. Five level Haar, Meyer, Symlets, and Coiflets wavelet transform decompositions of the post storm imagery are inputs to damage classification models of post hurricane and tornado damage. Hurricanes Ike, Rita, Katrina, and Ivan are examined as are the 2011 Joplin and Tuscaloosa tornadoes.

Wavelet transform-based classification methods yielded varying classification accuracies for the four hurricanes examined, ranging from 67 percent to 89 percent classification accuracy for classification models informed by samples from the storms …


An Analysis Of Fast Photochemistry Over High Northern Latitudes During Spring And Summer Using In-Situ Observations From Arctas And Topse, J R. Olson, J H. Crawford, William H. Brune, J Mao, Xinrong Ren, A Fried, B Anderson, E C. Apel, M Beaver, D R. Blake, G Chen, John D. Crounse, Jack E. Dibb, Glenn Diskin, S R. Hall, L Gregory Huey, D Knapp, D Richter, D Riemer, J St. Clair, Kirk Ullman, J Walega, P Weibring, Andrew Weinheimer, Paul Wennberg, Armin Wisthaler Aug 2012

An Analysis Of Fast Photochemistry Over High Northern Latitudes During Spring And Summer Using In-Situ Observations From Arctas And Topse, J R. Olson, J H. Crawford, William H. Brune, J Mao, Xinrong Ren, A Fried, B Anderson, E C. Apel, M Beaver, D R. Blake, G Chen, John D. Crounse, Jack E. Dibb, Glenn Diskin, S R. Hall, L Gregory Huey, D Knapp, D Richter, D Riemer, J St. Clair, Kirk Ullman, J Walega, P Weibring, Andrew Weinheimer, Paul Wennberg, Armin Wisthaler

Earth Sciences

Observations of chemical constituents and meteorological quantities obtained during the two Arctic phases of the airborne campaign ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) are analyzed using an observationally constrained steady state box model. Measurements of OH and HO2 from the Penn State ATHOS instrument are compared to model predictions. Forty percent of OH measurements below 2 km are at the limit of detection during the spring phase (ARCTAS-A). While the median observed-to-calculated ratio is near one, both the scatter of observations and the model uncertainty for OH are at the magnitude of …


A New Nonlinear Analytical Model For Canopy Flow Over A Forested Hill, Weiguo Wang, Chuixiang Yi Aug 2012

A New Nonlinear Analytical Model For Canopy Flow Over A Forested Hill, Weiguo Wang, Chuixiang Yi

Publications and Research

A new nonlinear analytical model for canopy flow over gentle hills is presented. This model is established based on the assumption that three major forces (pressure gradient, Reynolds stress gradient, and nonlinear canopy drag) within canopy are in balance for gentle hills under neutral conditions. The momentum governing equation is closed by the velocity-squared law. This new model has many advantages over the model developed by Finnigan and Belcher (2004, hereafter referred to as FB04) in predicting canopy wind velocity profiles in forested hills in that: (1) this model predictions are more realistic because the surface drag can be taken …


Identifying Signatures Of Plasma Waves And Reconnection Associated With Kelvin-Helmholtz Activity, Thomas Wesley Moore Aug 2012

Identifying Signatures Of Plasma Waves And Reconnection Associated With Kelvin-Helmholtz Activity, Thomas Wesley Moore

Doctoral Dissertations and Master's Theses

The magnetopause marks the boundary between the shocked solar wind and magnetospheric plasma. Understanding the dynamics of the plasma processes at the magnetopause boundary is crucial to the study of plasma transport into the magnetosphere. Previous studies have shown that there exists a temperature asymmetry in the plasma sheet. During northward IMF, the cold component ions are 30-40% hotter in the dawn flank plasma sheet compared to the dusk flank. However, the mechanisms responsible are still not entirely clear. Recent work has shown that reconnection in Kelvin-Helmholtz vortices can transport plasma into the magnetosphere. Previous studies have also shown that …


Accuracy Assessment Of Aqua-Modis Aerosol Optical Depth Over Coastal Regions: Importance Of Quality Flag And Sea Surface Wind Speed, Jacob Anderson Jul 2012

Accuracy Assessment Of Aqua-Modis Aerosol Optical Depth Over Coastal Regions: Importance Of Quality Flag And Sea Surface Wind Speed, Jacob Anderson

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Using data collected from 62 coastal stations worldwide from the Aerosol Robotic Network (AERONET) from 2002-2011, accuracy assessments are made for coastal aerosol optical depth (AOD) retrieved from MODIS aboard the Aqua satellite. It is found that coastal AODs (at 550 nm) characterized respectively by the MODIS Dark Land (Land) surface algorithm, the Open Ocean (Ocean) algorithm, and AERONET all exhibit a log-normal distribution. After filtering by quality flags, the coastal MODIS AODs retrieved from the Land and Ocean algorithms are highly correlated with AERONET (with R2≈0.8), but only the Land algorithm AODs fall within the expected error …


Modeling Chemistry In And Above Snow At Summit, Greenland – Part 2: Impact Of Snowpack Chemistry On The Oxidation Capacity Of The Boundary Layer, J L. Thomas, Jack E. Dibb, L Gregory Huey, J Liao, D Tanner, Barry Lefer, R Von Glasow, J Stutz Jul 2012

Modeling Chemistry In And Above Snow At Summit, Greenland – Part 2: Impact Of Snowpack Chemistry On The Oxidation Capacity Of The Boundary Layer, J L. Thomas, Jack E. Dibb, L Gregory Huey, J Liao, D Tanner, Barry Lefer, R Von Glasow, J Stutz

Earth Sciences

The chemical composition of the boundary layer in snow covered regions is impacted by chemistry in the snowpack via uptake, processing, and emission of atmospheric trace gases. We use the coupled one-dimensional (1-D) snow chemistry and atmospheric boundary layer model MISTRA-SNOW to study the impact of snowpack chemistry on the oxidation capacity of the boundary layer. The model includes gas phase photochemistry and chemical reactions both in the interstitial air and the atmosphere. While it is acknowledged that the chemistry occurring at ice surfaces may consist of a true quasi-liquid layer and/or a concentrated brine layer, lack of additional knowledge …


Ionospheric Signatures Of Tohoku-Oki Tsunami Of March 11, 2011: Model Comparisons Near The Epicenter, David A. Galvan, Attila Komjathy, Michael P. Hickey, Philip Stephens, Jonathan Snively, Y. Tony Song, Mark D. Butala, Anthony J. Mannucci Jul 2012

Ionospheric Signatures Of Tohoku-Oki Tsunami Of March 11, 2011: Model Comparisons Near The Epicenter, David A. Galvan, Attila Komjathy, Michael P. Hickey, Philip Stephens, Jonathan Snively, Y. Tony Song, Mark D. Butala, Anthony J. Mannucci

Publications

We observe ionospheric perturbations caused by the Tohoku earthquake and tsunami of March 11, 2011. Perturbations near the epicenter were found in measurements of ionospheric total electron content (TEC) from 1198 GPS receivers in the Japanese GEONET network. For the first time for this event, we compare these observations with the estimated magnitude and speed of a tsunami-driven atmospheric gravity wave, using an atmosphere-ionosphere-coupling model and a tsunami model of sea-surface height, respectively. Traveling ionospheric disturbances (TIDs) were observed moving away from the epicenter at approximate speeds of 3400 m/s, 1000 m/s and 200–300 m/s, consistent with Rayleigh waves, acoustic …


Near-Real-Time Global Biomass Burning Emissions Product From Geostationary Satellite Constellation, Xiaoyang Zhang, Shobha Kondragunta, Jessica Ram, Christopher Schmidt, Ho-Chung Huang Jul 2012

Near-Real-Time Global Biomass Burning Emissions Product From Geostationary Satellite Constellation, Xiaoyang Zhang, Shobha Kondragunta, Jessica Ram, Christopher Schmidt, Ho-Chung Huang

GSCE Faculty Publications

Near-real-time estimates of biomass burning emissions are crucial for air quality monitoring and forecasting. We present here the first near-real-time global biomass burning emission product from geostationary satellites (GBBEP-Geo) produced from satellite-derived fire radiative power (FRP) for individual fire pixels. Specifically, the FRP is retrieved using WF_ABBA V65 (wildfire automated biomass burning algorithm) from a network of multiple geostationary satellites. The network consists of two Geostationary Operational Environmental Satellites (GOES) which are operated by the National Oceanic and Atmospheric Administration, the Meteosat second-generation satellites (Meteosat-09) operated by the European Organisation for the Exploitation of Meteorological Satellites, and the Multifunctional Transport …


Halogen Activation Via Interactions With Environmental Ice And Snow In The Polar Lower Troposphere And Other Regions, J. P. D. Abbatt, J. L. Thomas, K. Abrahamsson, Chris Boxe, A. Granfors, A. E. Jones, M. D. King, A. Saiz-Lopez, P. B. Shepson, J. Sodeau, D. W. Toohey, C. Toubin, R. Von Glasow, S. N. Wren, X. Yang Jul 2012

Halogen Activation Via Interactions With Environmental Ice And Snow In The Polar Lower Troposphere And Other Regions, J. P. D. Abbatt, J. L. Thomas, K. Abrahamsson, Chris Boxe, A. Granfors, A. E. Jones, M. D. King, A. Saiz-Lopez, P. B. Shepson, J. Sodeau, D. W. Toohey, C. Toubin, R. Von Glasow, S. N. Wren, X. Yang

Publications and Research

The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the regional atmospheric oxidizing capacity in specific situations. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media upon which marine algae live. This paper reviews the nature of environmental ice substrates that participate in halogen chemistry, describes the reactions that occur on such substrates, presents the field evidence for ice-mediated halogen activation, summarizes our best understanding of ice-halogen activation mechanisms, and describes the current state of modeling …


Droughtscape, Summer 2012, National Drought Mitigation Center Jul 2012

Droughtscape, Summer 2012, National Drought Mitigation Center

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

Contents

Director’s report 1

Drought expanse 1

Upcoming ranch workshops. 3

Drought outlook and review 4

Spring impacts summary 6

Hawaii impact workshops 9

Remote sensing of drought. 10

China workshop . 12


Life Cycle Boundaries And Greenhouse Gas Emissions From Beef Cattle, Quentin M. Dudley Jul 2012

Life Cycle Boundaries And Greenhouse Gas Emissions From Beef Cattle, Quentin M. Dudley

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Beef cattle are estimated to directly contribute 26% of U.S. agricultural greenhouse gas (GHG) emissions, and future climate change policy may target reducing these emissions. Life cycle assessment (LCA) of GHG emissions from U.S. feedlot beef cattle was conducted to compare methods of the U.S. Environmental Protection Agency (EPA) with a more complete evaluation of emissions. The inclusion of emissions from crop production for feed, associated land use change, and other minor factors nearly doubled GHG emissions associated with beef feedlots from the EPA Annual Inventory estimate of 1611 kgCO2e hd-1 yr-1 to 3182 ± 167 …


Optimal Control Of Katabatic Flows Within Canopies, Hongbin Chen, Chuixiang Yi Jul 2012

Optimal Control Of Katabatic Flows Within Canopies, Hongbin Chen, Chuixiang Yi

Publications and Research

What slope angle favours the development of katabatic flow is still an open question. Some studies have clarified that katabatic winds are stronger on steep slopes, while others have demonstrated that katabatic winds are stronger on gentle slopes. Here, we explore the control mechanisms of katabatic flow using a simplified theoretical model in an attempt to clarify the causes of the paradoxical findings. Our results indicate that optimal conditions for katabatic flows within canopies are synergistically controlled by terrain angle, canopy structure and thermal condition through a simple equation:

LcVT-2 sin3 α = b,

where …


Upgraded Alo Rayleigh Lidar System And Its Improved Gravity Wave Measurements, Leda Sox, Vincent B. Wickwar, Joshua P. Herron, Marcus J. Bingham Jun 2012

Upgraded Alo Rayleigh Lidar System And Its Improved Gravity Wave Measurements, Leda Sox, Vincent B. Wickwar, Joshua P. Herron, Marcus J. Bingham

Graduate Student Posters

The Rayleigh-Scatter lidar system at the Atmospheric Lidar Observatory (ALO) on the Utah State campus is currently going through a series of upgrades to significantly improve its observational abilities. A specific objective of these upgrades is to expand the altitude range over which backscattered photons can be collected. A second objective is to increase the sensitivity of the instrument to be able to analyze the raw data at finer temporal and/or spatial resolutions. By measuring relative densities, the system will be able to produce absolute temperatures and relative density perturbations, which illustrate gravity wave structures. Gravity wave studies will significantly …


Estimating Annual Precipitation For The Colorado River Basin Using Oceanic-Atmospheric Oscillations, Ajay Kalra, Sajjad Ahmad Jun 2012

Estimating Annual Precipitation For The Colorado River Basin Using Oceanic-Atmospheric Oscillations, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Estimating long-lead time precipitation under the stress of increased climatic variability is a challenging task in the field of hydrology. A modified Support Vector Machine (SVM) based framework is proposed to estimate annual precipitation using oceanic-atmospheric oscillations. Oceanic-atmospheric oscillations, consisting of Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Niño–Southern Oscillation (ENSO) for a period of 1900–2008, are used to generate annual precipitation estimates with a 1 year lead time. The SVM model is applied to 17 climate divisions encompassing the Colorado River Basin in the western United States. The overall results revealed that …


Implementation Of Branch-Point-Tolerant Wavefront Reconstructor For Strong Turbulence Compensation, Michael J. Steinbock Jun 2012

Implementation Of Branch-Point-Tolerant Wavefront Reconstructor For Strong Turbulence Compensation, Michael J. Steinbock

Theses and Dissertations

Branch points arise in optical transmissions due to strong atmospheric turbulence, long propagation paths, or a combination of both. Unfortunately, these conditions are very often present in desired operational scenarios for laser weapon systems, optical communication, and covert imaging, which suffer greatly when traditional adaptive optics systems either cannot sense branch points or implement non-optimal methods for sensing and correcting branch points. Previous research by Pellizzari presented a thorough analysis of various novel branch point tolerant reconstructors in the absence of noise. In this research a realistic model of the Air Force Institute of Technology's adaptive optics system is developed …


Ionospheric Plasma Transport And Loss In Auroral Downward Current Regions, M. Zettergren, J. L. Semeter Jun 2012

Ionospheric Plasma Transport And Loss In Auroral Downward Current Regions, M. Zettergren, J. L. Semeter

Publications

A detailed study of the effects of auroral current systems on thermal ionospheric plasma transport and loss is conducted using a new ionospheric model. The mathematical formulation of the model is a variation on the 5‐moment approximation which describes the temporal evolution of density, drift, and temperature for five different ion species in two spatial dimensions. The fluid system is closed through a 2‐D electrostatic treatment of the auroral currents. This model is used to examine the interplay between ion heating, perpendicular transport, molecular ion generation, and type‐1 ion upflows in a self‐consistent way for the first time. Simulations confirm …


Reproduction Of Twentieth Century Intradecadal To Multidecadal Surface Temperature Variability In Radiatively Forced Coupled Climate Models, Patrick T. Brown, Eugene C. Cordero, Steven A. Mauget Jun 2012

Reproduction Of Twentieth Century Intradecadal To Multidecadal Surface Temperature Variability In Radiatively Forced Coupled Climate Models, Patrick T. Brown, Eugene C. Cordero, Steven A. Mauget

Faculty Publications, Meteorology and Climate Science

[1] Coupled Model Intercomparison Project 3 simulations that included time-varying radiative forcings were ranked according to their ability to consistently reproduce twentieth century intradecadal to multidecadal (IMD) surface temperature variability at the 5° by 5° spatial scale. IMD variability was identified using the running Mann-Whitney Z method. Model rankings were given context by comparing the IMD variability in preindustrial control runs to observations and by contrasting the IMD variability among the ensemble members within each model. These experiments confirmed that the inclusion of time-varying external forcings brought simulations into closer agreement with observations. Additionally, they illustrated that the magnitude of …


Assessment Of Gravity Wave Momentum Flux Measurement Capabilities By Meteor Radars Having Different Transmitter Power And Antenna Configurations, D. C. Fritts, D. Janches, W. K. Hocking, Michael J. Taylor May 2012

Assessment Of Gravity Wave Momentum Flux Measurement Capabilities By Meteor Radars Having Different Transmitter Power And Antenna Configurations, D. C. Fritts, D. Janches, W. K. Hocking, Michael J. Taylor

All Physics Faculty Publications

Measurement capabilities of five meteor radars are assessed and compared to determine how well radars having different transmitted power and antenna configurations perform in defining mean winds, tidal amplitudes, and gravity wave (GW) momentum fluxes. The five radars include two new-generation meteor radars on Tierra del Fuego, Argentina (53.8°S) and on King George Island in the Antarctic (62.1°S) and conventional meteor radars at Socorro, New Mexico (34.1°N, 106.9°W), Bear Lake Observatory, Utah (∼41.9°N, 111.4°W), and Yellowknife, Canada (62.5°N, 114.3°W). Our assessment employs observed meteor distributions for June of 2009, 2010, or 2011 for each radar and a set of seven …


Comparison Of Saber Oh Measurements To Rocket Photometry Data, Jordan Rozum, Gene A. Ware, Doran J. Baker May 2012

Comparison Of Saber Oh Measurements To Rocket Photometry Data, Jordan Rozum, Gene A. Ware, Doran J. Baker

Browse All Undergraduate research

In 2002, the Sounding of the Atmosphere us- ing Broadband Emission Radiometry (SABER) instru- ment aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite went online and has since been providing radiometric data concern- ing the mesosphere and lower thermosphere/ionosphere (MLTI) region of the atmosphere. Researchers at the Utah State University NASA Space Grant Consortium have been tasked with validating measurements of the hydroxyl airglow volume emission rates (VER) taken by SABER. To this end, we compare SABER measurements of the altitude distribution of hydroxyl airglow to mea- surements taken by photometers aboard rockets launched between 1961 and 1986 …


Atmospheric Circulation Change In The Central Himalayas Indicated By A High-Resolution Ice Core Deuterium Excess Record, Hongxi Pang, Shugui Hou, Susan Kaspari, Paul Mayewski, Douglas Introne, Valérie Masson-Delmotte, Jean Jouzel, Zhenchao Li, Yuanqing He, Sungmin Hong, Dahe Qin May 2012

Atmospheric Circulation Change In The Central Himalayas Indicated By A High-Resolution Ice Core Deuterium Excess Record, Hongxi Pang, Shugui Hou, Susan Kaspari, Paul Mayewski, Douglas Introne, Valérie Masson-Delmotte, Jean Jouzel, Zhenchao Li, Yuanqing He, Sungmin Hong, Dahe Qin

All Faculty Scholarship for the College of the Sciences

Continuous measurements of both δD and δ18O were performed along a 108.8 m ice core recovered from the East Rongbuk Glacier on the northeast saddle of Mt. Qomolangma (Everest) (28.03° N, 86.96° E, 6518 m above sea level) in September 2002. They provide the first high-resolution historical record of deuterium excess (d) in the central Himalayas. In this paper, we focus on d variability from 1951 to 2001 and its relationship with large scale atmospheric circulation. The d record exhibits significant seasonal variations, with low values in summer and high values in winter, reflecting the atmospheric circulation shift between winter …


Gravity Wave Propagation In A Diffusively Separated Gas: Effects On The Total Gas, Michael P. Hickey Ph.D., R. L. Walterscheid May 2012

Gravity Wave Propagation In A Diffusively Separated Gas: Effects On The Total Gas, Michael P. Hickey Ph.D., R. L. Walterscheid

Publications

We present a full-wave model that simulates acoustic-gravity wave propagation in a binary-gas mixture of atomic oxygen and molecular nitrogen, including molecular viscosity and thermal conductivity appropriately partitioned between the two gases. Compositional effects include the collisional transfer of heat and momentum by mutual diffusion between the two gases. An important result of compositional effects is that the velocity and temperature summed over species can be significantly different from the results of one-gas models with the same height dependent mean molecular weight (M(z)). We compare the results of our binary-gas model to two one-gas full-wave models: one where M is …


Large, Long-Lived Convective Systems Over Subtropical South America And Their Relationships With Atmospheric Teleconnections, Kyle Mattingly May 2012

Large, Long-Lived Convective Systems Over Subtropical South America And Their Relationships With Atmospheric Teleconnections, Kyle Mattingly

Mahurin Honors College Capstone Experience/Thesis Projects

This study provides a climatological assessment of persistent elongated convective systems (PECS) over subtropical South America during the austral warm seasons of 1998-2007 and a comparison of PECS frequency and physical characteristics to mesoscale convective complexes (MCCs) in the region. Relationships between the Antarctic Oscillation (AAO) and El Niño – Southern Oscillation (ENSO) teleconnections and large, long-lived convective systems (LLCSs) are explored. An average of 143 PECS and 37 MCCs occurred per warm season. PECS lasted longer on average than MCCs (17 hrs. vs. 14 hrs.) and reached a greater average maximum cloud-shield extent than MCCs (297,300 km2 vs. 256,500 …


An Evaluation Of Cape Tendency In Tornado Outbreaks, Timothy W. Humphrey, Lance F. Bosart May 2012

An Evaluation Of Cape Tendency In Tornado Outbreaks, Timothy W. Humphrey, Lance F. Bosart

Atmospheric & Environmental Sciences

Previous studies (e.g., Rasmussen, 2003; Thompson et al., 2003) have examined the impact that instability has on the occurrence of tornadic supercells. However, few studies (e.g., Calas et al., 2000) have examined the impact that the rate of destabilization has on the development of severe convection. Utilizing a CAPE tendency equation derived by Emanuel (1994), this study examines the impact of the rate of atmospheric destabilization on the severity of convection. Comparing six hour analyses of CAPE tendency with observed tornado tracks from the 4-6 May 2007, 5-6 February 2008, and 17 June 2010 tornado outbreaks reveals a potential correlation …


Largescale Precursors To Major Lake Effect Snowstorms Lee Of Lake Erie, Hannah E. Attard, Ross A. Lazear May 2012

Largescale Precursors To Major Lake Effect Snowstorms Lee Of Lake Erie, Hannah E. Attard, Ross A. Lazear

Atmospheric & Environmental Sciences

Lake‐effect snowstorms are primarily a mesoscale feature; however, major lakeeffect snowstorms are linked closely to their synoptic environment. Thus, a lakeeffect system which lasts for more than 24 h cannot only be explained by the boundary layer; it is also associated with the upper tropospheric flow. This research will address whether major lake‐effect snow events off of Lake Erie can also be associated with large‐scale planetary features several days prior to event onset. The goal is to aid in the forecast process by increasing the accuracy and leadtime of lake‐effect snow forecasts. This study includes 31 cases recorded from the …


The Rapid Intensification Of Hurricane Gustav (2008), Jason H. Keefer May 2012

The Rapid Intensification Of Hurricane Gustav (2008), Jason H. Keefer

Atmospheric & Environmental Sciences

Hurricane Gustav was one of two major hurricanes that occurred in the Atlantic basin during the 2008 hurricane season. The storm caused more than $6 billion U. S. dollars of damage in Haiti, Jamaica, Cuba, and along the coast of the Gulf of Mexico from 25 August 2008 to 5 September 2008. The greatest amount of damage and highest number of casualties produced by the storm can be attributed to the rapid intensification of the hurricane. Rapid intensification (RI) of a tropical cyclone is defined as an increase in maximum sustained winds by 15.4 m s⁻¹ (30 kts) in a …