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Articles 1111 - 1140 of 2456

Full-Text Articles in Atmospheric Sciences

Secondary Gravity Wave Generation Over New Zealand During The Deepwave Campaign, Katrina Bossert, Christopher G. Kruse, Christopher J. Heale, David C. Fritts, Bifford P. Williams, Jonathan B. Snively, Pierre-Dominique Pautet, Michael J. Taylor Aug 2017

Secondary Gravity Wave Generation Over New Zealand During The Deepwave Campaign, Katrina Bossert, Christopher G. Kruse, Christopher J. Heale, David C. Fritts, Bifford P. Williams, Jonathan B. Snively, Pierre-Dominique Pautet, Michael J. Taylor

Publications

Multiple events during the Deep Propagating Gravity Wave Experiment measurement program revealed mountain wave (MW) breaking at multiple altitudes over the Southern Island of New Zealand. These events were measured during several research flights from the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft, utilizing a Rayleigh lidar, an Na lidar, and an Advanced Mesospheric Temperature Mapper simultaneously. A flight on 29 June 2014 observed MWs with horizontal wavelengths of ~80–120 km breaking in the stratosphere from ~10 to 50 km altitude. A flight on 13 July 2014 observed a horizontal wavelength of ~200–240 km MW extending from …


Variability In Methane Emissions From West Siberia's Shallow Boreal Lakes On A Regional Scale And Its Environmental Controls, Aleksandr F. Sabrekov, Benjamin R.K. Runkle, Mikhail V. Glagolev, Irina E. Terentieva, Victor M. Stephanenko, Oleg R. Kotsyurbenko, Shamil S. Maksyutov, Oleg S. Pokrovsky Aug 2017

Variability In Methane Emissions From West Siberia's Shallow Boreal Lakes On A Regional Scale And Its Environmental Controls, Aleksandr F. Sabrekov, Benjamin R.K. Runkle, Mikhail V. Glagolev, Irina E. Terentieva, Victor M. Stephanenko, Oleg R. Kotsyurbenko, Shamil S. Maksyutov, Oleg S. Pokrovsky

Biological and Agricultural Engineering Faculty Publications and Presentations

Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July–August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m−2 h−1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m−2 h−1 for southern taiga lakes, respectively. …


Estimation Of Bubble-Mediated Air–Sea Gas Exchange From Concurrent Dms And Co2 Transfer Velocities At Intermediate–High Wind Speeds, Thomas G. Bell, Sebastian Landwehr, Scott D. Miller, Warren J. De Bruyn, Adrian H. Callaghan, Brian Scanlon, Brian Ward, Mingxi Yang, Eric S. Saltzman Jul 2017

Estimation Of Bubble-Mediated Air–Sea Gas Exchange From Concurrent Dms And Co2 Transfer Velocities At Intermediate–High Wind Speeds, Thomas G. Bell, Sebastian Landwehr, Scott D. Miller, Warren J. De Bruyn, Adrian H. Callaghan, Brian Scanlon, Brian Ward, Mingxi Yang, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Simultaneous air–sea fluxes and concentration differences of dimethylsulfide (DMS) and carbon dioxide (CO2/ were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the gas transfer velocities of these two gases (1kw/ over a range of wind speeds up to 21ms􀀀1. These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with 1kw, consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation …


Collaborative Research: Refining And Testing Methods For Identifying And Quantifying Gaseous Oxidized Mercury In Air, Seth Lyman Jul 2017

Collaborative Research: Refining And Testing Methods For Identifying And Quantifying Gaseous Oxidized Mercury In Air, Seth Lyman

Funded Research Records

No abstract provided.


The Mobile Monitoring Of Particulate Matter Through Wearable Sensors And Their Influence On Students' Environmental Attitudes, Joseph M. Abbate Jul 2017

The Mobile Monitoring Of Particulate Matter Through Wearable Sensors And Their Influence On Students' Environmental Attitudes, Joseph M. Abbate

DePaul Discoveries

While we have a comprehensive understanding of air pollutants, and their spatiotemporal characteristics across global, and even regional, scales, we are quite limited in our capacity to monitor neighborhood-scale emissions. The mobile monitoring of air pollution is a growing field, prospectively filling in these gaps while personalizing air quality-based tools and risk assessment. In the present study, we developed wearable sensors for particulate matter (PM); and through a citizen science approach, students of partnering Chicago schools monitored PM concentrations throughout their commutes over a five-day period. While their recorded findings would be used to explore the relationship between PM concentrations …


Mesonets: Mesoscale Weather And Climate Observations For The United States, Rezaul Mahmood, Ryan Boyles, Kevin Brinson, Christopher Fiebrich, Stuart Foster, Ken Hubbard, David Robinson, Jeff Andresen, Dan Leathers Jul 2017

Mesonets: Mesoscale Weather And Climate Observations For The United States, Rezaul Mahmood, Ryan Boyles, Kevin Brinson, Christopher Fiebrich, Stuart Foster, Ken Hubbard, David Robinson, Jeff Andresen, Dan Leathers

High Plains Regional Climate Center: Staff Publications

Mesoscale in situ meteorological observations are essential for better understanding and forecasting the weather and climate and to aid in decision-making by a myriad of stakeholder communities. They include, for example, state environmental and emergency management agencies, the commercial sector, media, agriculture, and the general public. Over the last three decades, a number of mesoscale weather and climate observation networks have become operational. These networks are known as mesonets. Most are operated by universities and receive different levels of funding. It is important to communicate the current status and critical roles the mesonets play. Most mesonets collect standard meteorological data …


Droughtscape, Summer 2017, National Drought Mitigation Center Jul 2017

Droughtscape, Summer 2017, National Drought Mitigation Center

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

Contents

Drought policy write shops conclude in Caribbean

Drought encroaches on Northern Plains in second quarter

Impact tool racks up submissions in second quarter

Maps on new website highlight drought effects on ag industry

Centers release new flash drought tool: QuickDRI

NDMC contributes to EU report on disaster risk management

Groups earn Climate Adaptation award for work with tribes

NDMC, ICPAC director talk collaboration on drought in Greater Horn of Africa

Up next in MENA: Drought vulnerability assessments


Mipas Imk/Iaa Carbon Tetrachloride (Ccl4) Retrieval And First Comparison With Other Instruments, Ellen Eckert, Thomas Von Clarmann, Alexandra Laeng, Gabriele P. Stiller, Bernd Funke, Norbert Glatthor, Udo Grabowski, Sylvia Kellmann, Michael Kiefer, Andrea Linden, Peter F. Bernath Jul 2017

Mipas Imk/Iaa Carbon Tetrachloride (Ccl4) Retrieval And First Comparison With Other Instruments, Ellen Eckert, Thomas Von Clarmann, Alexandra Laeng, Gabriele P. Stiller, Bernd Funke, Norbert Glatthor, Udo Grabowski, Sylvia Kellmann, Michael Kiefer, Andrea Linden, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

MIPAS thermal limb emission measurements were used to derive vertically resolved profiles of carbon tetrachloride (CCl4). Level-1b data versions MIPAS/5.02 to MIPAS/5.06 were converted into volume mixing ratio profiles using the level-2 processor developed at Karlsruhe Institute of Technology (KIT) Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Cientificas (CSIC), Instituto de Astrofisica de Andalucia (IAA). Consideration of peroxyacetyl nitrate (PAN) as an interfering species, which is jointly retrieved, and CO2 line mixing is crucial for reliable retrievals. Parts of the CO2 Q-branch region that overlap with the CCl4 signature were …


Improved Ballistic Wind Prediction Using Projectile Tracking Data, William Arthur Kenney Jul 2017

Improved Ballistic Wind Prediction Using Projectile Tracking Data, William Arthur Kenney

Computational Modeling & Simulation Engineering Theses & Dissertations

The United States Air Force AC-130 gunships have been in operation since the Vietnam War and have seen frequent use during recent conflicts. They are able to employ gun weapon systems from above a target in a way that maximizes possible time on target. When firing, the gun operators must deal with miss distances caused by winds acting on the projectile in flight. Operators currently perform a “tweak” to predict a ballistic wind affecting fired rounds which is then used in the fire-control to correct for the real winds and bring shots onto target. This correction, a single-point wind prediction, …


Cedar: Mesospheric Investigation Of Gravity Wave And Mountain Wave Activities And Impacts In The Lee Side Of The Southern Andes, Pierre-Dominique Pautet Jul 2017

Cedar: Mesospheric Investigation Of Gravity Wave And Mountain Wave Activities And Impacts In The Lee Side Of The Southern Andes, Pierre-Dominique Pautet

Funded Research Records

No abstract provided.


High Resolution Spectra Of Carbon Monoxide, Propane And Ammonia For Atmospheric Remote Sensing, Christopher Andrew Beale Jul 2017

High Resolution Spectra Of Carbon Monoxide, Propane And Ammonia For Atmospheric Remote Sensing, Christopher Andrew Beale

OES Theses and Dissertations

Spectroscopy is a critical tool for analyzing atmospheric data. Identification of atmospheric parameters such as temperature, pressure and the existence and concentrations of constituent gases via remote sensing techniques are only possible with spectroscopic data. These form the basis of model atmospheres which may be compared to observations to determine such parameters. To this end, this dissertation explores the spectroscopy of three molecules: ammonia, propane and carbon monoxide.

Infrared spectra have been recorded for ammonia in the region 2400-9000 cm-1. These spectra were recorded at elevated temperatures (from 293-973 K) using a Fourier Transform Spectrometer (FTS). Comparison between …


Observations Of Greenhouse Gas Isotopologues With Ace-Fts And Waccm, Eric Michael Buzan Jul 2017

Observations Of Greenhouse Gas Isotopologues With Ace-Fts And Waccm, Eric Michael Buzan

Chemistry & Biochemistry Theses & Dissertations

Increases in greenhouse gas concentrations in the atmosphere are the major driver of climate change. Quantifying the sources and sinks of these gases is a major focus of research. Measuring isotopologues, or molecules that differ in isotopic composition, is one useful way of constraining the budget of a molecule as they are highly sensitive to different sources and sinks. However, measurements above the surface have been restricted to a few locations and have only reached the lower stratosphere. Satellite-based remote sensing can achieve nearly global measurement coverage, but so far no satellites have measured isotopologues.

Presented here are measurements of …


Satellite Observation Of Ch4 And Co Anomalies Associated With The Wenchuan Ms 8.0 And Lushan Ms 7.0 Earthquakes In China, Y. Cui, Dimitar Ouzounov, N. Hatzopoulos, K. Sun, Z. Zou, J. Du Jun 2017

Satellite Observation Of Ch4 And Co Anomalies Associated With The Wenchuan Ms 8.0 And Lushan Ms 7.0 Earthquakes In China, Y. Cui, Dimitar Ouzounov, N. Hatzopoulos, K. Sun, Z. Zou, J. Du

Mathematics, Physics, and Computer Science Faculty Articles and Research

Spatial and temporal variations of total column of CH4 and CO (TotCH4 and TotCO) associated with the 12 May 2008 Wenchuan and 20 April 2013 Lushan earthquakes in western Sichuan, China were investigated using satellite data from AQUA AIRS in order to understand the lithospheric and atmospheric interactions during the seismic activity. The Wenchuan MS 8.0 and Lushan MS7.0 earthquakes occurred in the Longmenshan fault zone. It was observed that large amounts of gases emitted from the earth's crust into the atmosphere before, during and after the earthquakes. The anomalies of TotCH4 and TotCO occurred along the …


Opal Cubesat Data Analysis Model, Kenneth Zia, Ludger Scherliess, Michael J. Taylor Jun 2017

Opal Cubesat Data Analysis Model, Kenneth Zia, Ludger Scherliess, Michael J. Taylor

Physics Student Research

Understanding the Earth’s lower thermosphere (altitude range 9 km -140km) is of growing interest for many areas of research within the space weather community. The NSF sponsored OPAL (Optical Profiling of the Atmospheric Limb) mission is designed to measure temperature profile by observing the integrated line of sight of the day-time O2 A-band (~760nm) emissions on the limb. The OPAL instrument has an altitude resolution of 1.03km from 80-160km flown on a 3U CubeSat, and is expected to be launched from the ISS (International Space Station) (~400km altitude). We have developed a model of OPAL’s position and attitude of its …


The Spatiotemporal Distribution Of Air Pollutants And Their Relationship With Land-Use Patterns In Hangzhou City, China, Sheng Zheng, Xueyuan Zhou, Ramesh Singh, Yuzhe Wu, Yanmei Ye, Cifang Wu Jun 2017

The Spatiotemporal Distribution Of Air Pollutants And Their Relationship With Land-Use Patterns In Hangzhou City, China, Sheng Zheng, Xueyuan Zhou, Ramesh Singh, Yuzhe Wu, Yanmei Ye, Cifang Wu

Mathematics, Physics, and Computer Science Faculty Articles and Research

Air pollution contributes to a large fraction of the total mortality estimated under the global burden of disease project (GBD) of the World Health Organization (WHO). This paper discusses an integrated study to obtain the spatiotemporal characteristics of particulate matter (PM10 and PM2.5) and trace gases (O3, SO2, NO2, and CO) pollutants in Hangzhou City (China) for the years 2014–2016. Our detailed analysis shows a relationship between air pollutants and land-use/land-cover change. Air quality parameters (PM2.5 and PM10) and trace gases (SO2, NO2, and CO) show strong monthly variations in the months of January (higher values) and July (lower values). …


Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst Jun 2017

Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst

Theses and Dissertations

Airborne hyperspectral imaging (HSI) in the LWIR has shown utility in material detection and identification. This research seeks to determine the most effective methods to perform model-based atmospheric compensation of LWIR HSI data by comparing results obtained from different atmospheric profiles. The standard model for mid-latitude summer (MLS) and radiosonde data are compared to the National Operational Model Archive and Distribution System (NOMADS) numerical weather predictions and the Extreme and Percentile Environmental Reference Tables (ExPERT). The two latter atmospheric profiles are generated using the Laser Environmental Effects Definition and Reference (LEEDR) software. MLS has been a standard starting point for …


First Na Lidar Measurements Of Turbulence Heat Flux, Thermal Diffusivity, And Energy Dissipation Rate In The Mesopause Region, Yafang Guo, Alan Z. Liu, Chester S. Gardner Jun 2017

First Na Lidar Measurements Of Turbulence Heat Flux, Thermal Diffusivity, And Energy Dissipation Rate In The Mesopause Region, Yafang Guo, Alan Z. Liu, Chester S. Gardner

Publications

Turbulence is ubiquitous in the mesopause region, where the atmospheric stability is low and wave breaking is frequent. Measuring turbulence is challenging in this region and is traditionally done by rocket soundings and radars. In this work, we show for the first time that the modern Na wind/temperature lidar located at Andes Lidar Observatory in Cerro Pachón, Chile, is able to directly measure the turbulence perturbations in temperature and vertical wind between 85 and 100 km. Using 150 h of lidar observations, we derived the frequency (ω) and vertical wave number (m) spectra for both gravity …


Umphlett Qci June 2017, Natalie Umphlett Jun 2017

Umphlett Qci June 2017, Natalie Umphlett

High Plains Regional Climate Center: Staff Publications

Highlights for the Basin

Temperature and Precipitation Anomalies

Snowpack and Streamflow

Historic Flooding in Missouri

Spring Conditions Impact Agriculture

3-Month Precipitation and Temperature Outlooks

U.S. Seasonal Drought Outlook


Comment On "Using An Adcp To Estimate Turbulent Kinetic Energy Dissipation Rate In Sheltered Coastal Waters", Ann E. Gargett Jun 2017

Comment On "Using An Adcp To Estimate Turbulent Kinetic Energy Dissipation Rate In Sheltered Coastal Waters", Ann E. Gargett

CCPO Publications

Greene et al. revisit the suggestion that the turbulent kinetic energy dissipation rate could be estimated through a "large-eddy estimate," employing acoustic measurements of velocity fields associated with the largest energy-containing scales of ocean turbulence. While the large-eddy estimate as originally proposed used vertical velocity and a vertical eddy length scale, Greene et al. chose instead to substitute a horizontal length scale for the latter. This comment argues that combining a horizontal scale for length with a vertical velocity scale produces a large-eddy estimate of the dissipation rate that is accurate only if the energy-containing eddies are isotropic, and that …


Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath Jun 2017

Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Novel airborne in situ measurements of inorganic chlorine, nitrogen oxide species, and ozone were performed inside the lower Antarctic polar vortex and at its edge in September 2012. We focus on one flight during the Transport and Composition of the LMS/Earth System Model Validation (TACTS/ESMVal) campaign with the German research aircraft HALO (High-Altitude LOng range research aircraft), reaching latitudes of 65°S and potential temperatures up to 405 K. Using the early winter correlations of reactive trace gases with N2O from the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), we find high depletion of chlorine reservoir gases up to ∼40% …


The Indianapolis Flux Experiment (Influx): A Test-Bed For Developing Urban Greenhouse Gas Emission Measurements, Kenneth J. Davis, Aijun Deng, Thomas Lauvaux, Natasha Miles, Scott Richardson, Daniel Sarmiento, Kevin R. Gurney, R Michael Hardesty, Timothy A. Bonin, W Alan Brewer, Brian K. Lamb, Paul B. Shepson, Rebecca M. Harvey, Maria Obiminda L. Cambaliza, Colm Sweeney, Jocelyn Turnbull, James Whetstone, Anna Karion May 2017

The Indianapolis Flux Experiment (Influx): A Test-Bed For Developing Urban Greenhouse Gas Emission Measurements, Kenneth J. Davis, Aijun Deng, Thomas Lauvaux, Natasha Miles, Scott Richardson, Daniel Sarmiento, Kevin R. Gurney, R Michael Hardesty, Timothy A. Bonin, W Alan Brewer, Brian K. Lamb, Paul B. Shepson, Rebecca M. Harvey, Maria Obiminda L. Cambaliza, Colm Sweeney, Jocelyn Turnbull, James Whetstone, Anna Karion

Physics Faculty Publications

The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX’s scientific objectives are to quantify CO2 and CH4 emission rates at 1 km2 resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar skill, and to achieve high (weekly or finer) temporal resolution at both spatial resolutions. The experiment employs atmospheric GHG measurements from both towers and aircraft, atmospheric transport observations and models, and activity-based inventory products to quantify urban GHG emissions. Multiple, independent methods for estimating urban emissions are a …


Proposed Legislation Seeks To Stimulate Investment In Coastal Resiliency, Jon Cawley May 2017

Proposed Legislation Seeks To Stimulate Investment In Coastal Resiliency, Jon Cawley

News Items

No abstract provided.


Concentrations And Size Distributions Of Bacteria-Containing Particles Over Oceans From China To The Arctic Ocean, Ming Li, Xiawei Yu, Hui Kang, Zhouqing Xie, Pengfei Zhang May 2017

Concentrations And Size Distributions Of Bacteria-Containing Particles Over Oceans From China To The Arctic Ocean, Ming Li, Xiawei Yu, Hui Kang, Zhouqing Xie, Pengfei Zhang

Publications and Research

During the third China Arctic Research Expedition (July–September 2008), size-resolved measurements of bacteria-containing particles (BCPs) in the marine boundary layer (MBL) air were conducted during a cruise through the East China Sea, the Yellow Sea, the Japan Sea, the Okhotsk Sea, the Bering Sea, the Chukchi Sea, and the Arctic Ocean. The concentrations of total airborne BCPs (TBCPs), non-salt tolerant airborne BCPs (NSBCPs), and salt tolerant airborne BCPs (SBCPs) varied from 29 to 955 CFU m − 3 (CFU = Colony Forming Unit), 16 to 919 CFU m − 3 , and 4 to 276 CFU m − 3 , …


The Role Of Sulfur Dioxide In Stratospheric Aerosol Formation Evaluated By Using In Situ Measurements In The Tropical Lower Stratosphere, A. W. Rollins, T. D. Thornberry, L. A. Watts, P. Yu, K. H. Rosenlof, M. Mills, E. Baumann, F. R. Giorgetta, T. V. Bui, M. Höpfner, P. F. Bernath May 2017

The Role Of Sulfur Dioxide In Stratospheric Aerosol Formation Evaluated By Using In Situ Measurements In The Tropical Lower Stratosphere, A. W. Rollins, T. D. Thornberry, L. A. Watts, P. Yu, K. H. Rosenlof, M. Mills, E. Baumann, F. R. Giorgetta, T. V. Bui, M. Höpfner, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Stratospheric aerosols (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (geoengineering). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of …


Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas May 2017

Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas

Doctoral Dissertations and Master's Theses

With renewed interest in planetary atmospheric entry, descent, and landing, NASA has noted a need for improved physics modeling in computational fluid dynamics. Uncertainty in experimental data used in radiation heat transfer computations leads to “over-engineering” of entry body heat shields, at large weight and cost penalties. There is interest in developing hypersonic thermophysics models from the known “first principles” of physics.

A method for computing high temperature gas emissivity and absorptivity from quantum mechanics principles is developed. The Schroedinger wave equation is cast as a discretized matrix eigenvalue problem which is solved using the ERAU parallel supercomputer. The numerical …


Solar Wind-Magnetosphere Coupling: A Global Perspective Of Reconnection In The Magnetotail, Miles Thomas Bengtson May 2017

Solar Wind-Magnetosphere Coupling: A Global Perspective Of Reconnection In The Magnetotail, Miles Thomas Bengtson

Doctoral Dissertations and Master's Theses

We present a case study of the 25 December 2015 substorm which occurred between 08:15 and 08:45 Universal Time. During this interval, fast particle flows and field geometry consistent with magnetic reconnection were detected in the mid-tail region. An ejected plasmoid was observed by the lunar-orbiting Acceleration, Reconnection, Turbulence and Electrodynamics of Moon’s Interaction with the Sun (ARTEMIS) probes and corresponding dipolarization signature was observed by the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft earthward of the reconnection site, which was determined to be approximately -33 RE. Ground signatures indicative of substorm activity were also observed …


A Global Study Of Gpp Focusing On Light-Use Efficiency In A Random Forest Regression Model, Suhua Wei, Chuixiang Yi, Wei Fang, George Hendrey May 2017

A Global Study Of Gpp Focusing On Light-Use Efficiency In A Random Forest Regression Model, Suhua Wei, Chuixiang Yi, Wei Fang, George Hendrey

Publications and Research

Light-use efficiency (LUE) is at the core of mechanistic modeling of global gross primary production (GPP). However, most LUE estimates in global models are satellite based and coarsely measured with emphasis on environmental variables. Others are from eddy covariance towers with much greater spatial and temporal data quality and emphasis on mechanistic processes, but in a limited number of sites. In this study, we conducted a comprehensive global study of tower-based LUE from 237 FLUXNET towers, and scaled up LUEs from in situ tower level to global biome level. We integrated the tower-based LUE estimates with key environmental and biological …


Design And Characterization Of A Time-Of-Flight Mass Spectrometer For Composition Measurements In The Upper Atmosphere, E. Addison Everett May 2017

Design And Characterization Of A Time-Of-Flight Mass Spectrometer For Composition Measurements In The Upper Atmosphere, E. Addison Everett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The mesosphere/lower thermosphere (MLT) is perhaps the least understood region of Earth's atmosphere. Too high for balloons and winged aircraft, yet too low for satellites, direct access to the MLT to make in-situ measurements is via high-speed sounding rockets for brief periods of at most a few minutes. Mass spectrometers have previously been used to make composition measurements in this region. But, mass spectrometry in the MLT is difficult, mainly due to the ambient pressures here and also the high speeds and short flight durations of sounding rocket missions. Time-of-flight mass spectrometers (TOF-MS) are capable of making fast, accurate measurements …


Direct Comparisons Of Ice Cloud Macro- And Microphysical Properties Simulated By The Community Atmosphere Model Version 5 With Hippo Aircraft Observations, Chenglai Wu, Xiaohong Liu, Minghui Diao, Kai Zhang, Andrew Gettelman, Zheng Lu, Joyce Penner, Zhaohui Lin Apr 2017

Direct Comparisons Of Ice Cloud Macro- And Microphysical Properties Simulated By The Community Atmosphere Model Version 5 With Hippo Aircraft Observations, Chenglai Wu, Xiaohong Liu, Minghui Diao, Kai Zhang, Andrew Gettelman, Zheng Lu, Joyce Penner, Zhaohui Lin

Faculty Publications, Meteorology and Climate Science

In this study we evaluate cloud properties simulated by the Community Atmosphere Model version 5 (CAM5) using in situ measurements from the HIAPER Pole-to-Pole Observations (HIPPO) campaign for the period of 2009 to 2011. The modeled wind and temperature are nudged towards reanalysis. Model results collocated with HIPPO flight tracks are directly compared with the observations, and model sensitivities to the representations of ice nucleation and growth are also examined. Generally, CAM5 is able to capture specific cloud systems in terms of vertical configuration and horizontal extension. In total, the model reproduces 79.8 % of observed cloud occurrences inside model …


Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman Apr 2017

Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman

Chemistry Faculty Publications

Anthropogenic activities contribute benzene, toluene, and anisole to the environment, which in the atmosphere are converted into the respective phenols, cresols, and methoxyphenols by fast gas-phase reaction with hydroxyl radicals (HO(•)). Further processing of the latter species by HO(•) decreases their vapor pressure as a second hydroxyl group is incorporated to accelerate their oxidative aging at interfaces and in aqueous particles. This work shows how catechol, pyrogallol, 3-methylcatechol, 4-methylcatechol, and 3-methoxycatechol (all proxies for oxygenated aromatics derived from benzene, toluene, and anisole) react at the air-water interface with increasing O3(g) during τc ≈ 1 μs contact time and contrasts their …