Open Access. Powered by Scholars. Published by Universities.®

Oceanography and Atmospheric Sciences and Meteorology Commons™

Open Access. Powered by Scholars. Published by Universities.®

Atmospheric Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 2221 - 2250 of 2458

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Seasonal Distributions Of Fine Aerosol Sulfate In The North American Arctic Basin During Topse, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, Barry Lefer Feb 2003

Seasonal Distributions Of Fine Aerosol Sulfate In The North American Arctic Basin During Topse, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, Barry Lefer

Earth Sciences

We used the mist chamber/ion chromatography technique to quantify fine aerosol SO4=(<2.7 μm) in the Arctic during the Tropospheric Ozone Production about the Spring Equinox Experiment (TOPSE) with about 2.5 min time resolution. Our effective sample area ranged from 50° to 86°N and 53° to 100°W. The seasonal evolution of fine aerosol sulfate in the Arctic troposphere during TOPSE was consistent with the phenomenon of Arctic haze. Arctic haze has been attributed to pollution from sources in the Arctic and pollution transported meridionally along stable isentropes into the Arctic in geographically broad but vertically narrow bands. These layers became more prevalent at higher altitudes as the season progressed toward summer, and the relevant isentropes are not held so close to the surface. Mean fine particle SO4= mixing ratios during TOPSE in February below 1000 m were elevated (112 pptv) and highly variable (between 28 and 290 pptv) but were significantly lower at higher altitudes (about 40 pptv). As the season progressed, elevated mixing ratios and higher variability were observed at higher altitudes, up to 7 km. In May, mixing ratios at the lowest altitudes declined but still remained higher than in February at all altitudes. The high variability in our measurements likely reflects the vertical heterogeneity of the wintertime …

Go to article

An Estimate Of The Stratospheric Contribution To Springtime Tropospheric Ozone Maxima Using Topse Measurements And Beryllium-7 Simulations, Dale J. Allen, Jack E. Dibb, Brian Ridley, Kenneth E. Pickering, R. Talbot Feb 2003

An Estimate Of The Stratospheric Contribution To Springtime Tropospheric Ozone Maxima Using Topse Measurements And Beryllium-7 Simulations, Dale J. Allen, Jack E. Dibb, Brian Ridley, Kenneth E. Pickering, R. Talbot

Earth Sciences

Measurements of tropospheric ozone (O3) between 30°N and 70°N show springtime maxima at remote locations. The contribution of seasonal changes in stratosphere–troposphere exchange (STE) to these maxima was investigated using measurements from the Tropospheric Ozone Production about the Spring Equinox Experiment (TOPSE) campaign and the beryllium-7 (7Be) distribution from a calculation driven by fields from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). Comparison with TOPSE measurements revealed that upper tropospheric model-calculated 7Be mixing ratios were reasonable (a change from previous calculations) but that lower tropospheric mixing ratios were too low most likely …

Go to article

Coupled Evolution Of Brox-Clox-Hox-Nox Chemistry During Bromine-Catalyzed Ozone Depletion Events In The Arctic Boundary Layer, M J. Evans, D J. Jacob, E L. Atlas, C A. Cantrell, Fred Eisele, F Flocke, A Fried, R L. Mauldin, Brian Ridley, B Wert, R. Talbot, D R. Blake, B J. Heikes, J Snow, J Walega, Andrew Weinheimer, Jack E. Dibb Feb 2003

Coupled Evolution Of Brox-Clox-Hox-Nox Chemistry During Bromine-Catalyzed Ozone Depletion Events In The Arctic Boundary Layer, M J. Evans, D J. Jacob, E L. Atlas, C A. Cantrell, Fred Eisele, F Flocke, A Fried, R L. Mauldin, Brian Ridley, B Wert, R. Talbot, D R. Blake, B J. Heikes, J Snow, J Walega, Andrew Weinheimer, Jack E. Dibb

Earth Sciences

Extensive chemical characterization of ozone (O3) depletion events in the Arctic boundary layer during the TOPSE aircraft mission in March–May 2000 enables analysis of the coupled chemical evolution of bromine (BrOx), chlorine (ClOx), hydrogen oxide (HOx) and nitrogen oxide (NOx) radicals during these events. We project the TOPSE observations onto an O3 chemical coordinate to construct a chronology of radical chemistry during O3 depletion events, and we compare this chronology to results from a photochemical model simulation. Comparison of observed trends in ethyne (oxidized by Br) and ethane …

Go to article

Stratospheric Influence On The Northern North American Free Troposphere During Topse: 7be As A Stratospheric Tracer, Jack E. Dibb, R. Talbot, Eric Scheuer, Garry Seid, Linsey J. Debell, Barry Lefer, Brian Ridley Feb 2003

Stratospheric Influence On The Northern North American Free Troposphere During Topse: 7be As A Stratospheric Tracer, Jack E. Dibb, R. Talbot, Eric Scheuer, Garry Seid, Linsey J. Debell, Barry Lefer, Brian Ridley

Earth Sciences

We use 7Be, with HNO3 and O3, to identify air masses sampled from the NCAR C-130 during TOPSE that retained clear evidence of stratospheric influence. A total of 43 such air masses, spread fairly evenly across the February to May sampling period, and 40°N–86°N latitude range, were encountered. South of 55°N, nearly all clear stratospheric influence was restricted to altitudes above 6 km. At higher latitudes stratospherically influenced air masses were encountered as low as 2 km. Approximately 12% of all TOPSE sampling time at altitudes above 2 km was spent in stratospherically impacted air, above …

Go to article

Ozone Depletion Events Observed In The High Latitude Surface Layer During The Topse Aircraft Program, Brian Ridley, Elliot Atlas, D Montzka, Edward V. Browell, C A. Cantrell, D R. Blake, N J. Blake, L Cinquini, Michael T. Coffey, L K. Emmons, Ronald C. Cohen, Russell J. Deyoung, Jack E. Dibb, Fred Eisele, F Flocke, A Fried, F E. Grahek, William B. Grant, Jonathan Hair, James W. Hannigan, B J. Heikes, Barry Lefer, R L. Mauldin, Jennie Moody, R E. Shetter, J Snow, R. Talbot, J A. Thornton, J Walega, Andrew Weinheimer, B Wert, Anthony Wimmers Feb 2003

Ozone Depletion Events Observed In The High Latitude Surface Layer During The Topse Aircraft Program, Brian Ridley, Elliot Atlas, D Montzka, Edward V. Browell, C A. Cantrell, D R. Blake, N J. Blake, L Cinquini, Michael T. Coffey, L K. Emmons, Ronald C. Cohen, Russell J. Deyoung, Jack E. Dibb, Fred Eisele, F Flocke, A Fried, F E. Grahek, William B. Grant, Jonathan Hair, James W. Hannigan, B J. Heikes, Barry Lefer, R L. Mauldin, Jennie Moody, R E. Shetter, J Snow, R. Talbot, J A. Thornton, J Walega, Andrew Weinheimer, B Wert, Anthony Wimmers

Earth Sciences

During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) aircraft program, ozone depletion events (ODEs) in the high latitude surface layer were investigated using lidar and in situ instruments. Flight legs of 100 km or longer distance were flown 32 times at 30 m altitude over a variety of regions north of 58° between early February and late May 2000. ODEs were found on each flight over the Arctic Ocean but their occurrence was rare at more southern latitudes. However, large area events with depletion to over 2 km altitude in one case were found as far south as …

Go to article

Investigations Into Free Tropospheric New Particle Formation In The Central Canadian Arctic During The Winter/Spring Transition As Part Of Topse, R J. Weber, D A. Orsini, B Wang, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, R L. Mauldin, E Kosciuch, C A. Cantrell, Fred Eisele Feb 2003

Investigations Into Free Tropospheric New Particle Formation In The Central Canadian Arctic During The Winter/Spring Transition As Part Of Topse, R J. Weber, D A. Orsini, B Wang, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, R L. Mauldin, E Kosciuch, C A. Cantrell, Fred Eisele

Earth Sciences

In this paper, we investigate the role of in situ new particle production in the central Canadian sub-Arctic and Arctic as part of the TOPSE experiment. Airborne measurements conducted primarily in the free troposphere were made from 50° to 90°W longitude and 60° to 85°N latitude during the period from February to May 2000. Data pertinent to this paper include 3–4 nm diameter (Dp) particles, ultrafine condensation nuclei (Dp > 3 nm), fine particles (0.2 < Dp < 3 μm), and the possible nucleation precursor, sulfuric acid, and its precursor, sulfur dioxide. For data averaged over this period, most species showed little evidence for a latitudinal trend. Fine aerosol number concentrations, however, showed a slight increase with latitude. The evolution of various species concentrations over the period of the study show that fine particles also had a consistent temporal trend, increasing at all altitudes from February to May, whereas sulfur dioxide at the surface tended to peak in late March. Ultrafine condensation nuclei and 3–4 nm particles showed no temporal trends. Little evidence for in situ new particle production was observed during the study, except for one atypical event where SO2concentrations were 3.5 ppbv, 2 orders of magnitude higher than typical levels. This paper cannot address the question of whether the observed condensation nuclei were …

Go to article

Steady State Free Radical Budgets And Ozone Photochemistry During Topse, C A. Cantrell, Lee Mauldin, M Zondlo, Fred Eisele, E Kosciuch, R E. Shetter, Barry Lefer, S R. Hall, T L. Campos, Brian Ridley, J Walega, A Fried, B Wert, F Flocke, Andrew Weinheimer, James W. Hannigan, Michael T. Coffey, Elliot Atlas, S Stephens, B J. Heikes, J Snow, D R. Blake, N J. Blake, A Katzenstein, J Lopez, Edward V. Browell, Jack E. Dibb, Eric Scheuer, Garry Seid, R. Talbot Feb 2003

Steady State Free Radical Budgets And Ozone Photochemistry During Topse, C A. Cantrell, Lee Mauldin, M Zondlo, Fred Eisele, E Kosciuch, R E. Shetter, Barry Lefer, S R. Hall, T L. Campos, Brian Ridley, J Walega, A Fried, B Wert, F Flocke, Andrew Weinheimer, James W. Hannigan, Michael T. Coffey, Elliot Atlas, S Stephens, B J. Heikes, J Snow, D R. Blake, N J. Blake, A Katzenstein, J Lopez, Edward V. Browell, Jack E. Dibb, Eric Scheuer, Garry Seid, R. Talbot

Earth Sciences

A steady state model, constrained by a number of measured quantities, was used to derive peroxy radical levels for the conditions of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign. The analysis is made using data collected aboard the NCAR/NSF C-130 aircraft from February through May 2000 at latitudes from 40° to 85°N, and at altitudes from the surface to 7.6 km. HO2 + RO2 radical concentrations were measured during the experiment, which are compared with model results over the domain of the study showing good agreement on the average. Average measurement/model ratios are 1.04 (σ …

Go to article

Springtime Photochemistry At Northern Mid And High Latitudes, Yuhang Wang, Brian Ridley, A Fried, C A. Cantrell, D D. Davis, Gao Chen, J Snow, B J. Heikes, R. Talbot, Jack E. Dibb, F Flocke, Andrew Weinheimer, N J. Blake, D R. Blake, R E. Shetter, Barry Lefer, Elliot Atlas, Michael T. Coffey, J Walega, B Wert Feb 2003

Springtime Photochemistry At Northern Mid And High Latitudes, Yuhang Wang, Brian Ridley, A Fried, C A. Cantrell, D D. Davis, Gao Chen, J Snow, B J. Heikes, R. Talbot, Jack E. Dibb, F Flocke, Andrew Weinheimer, N J. Blake, D R. Blake, R E. Shetter, Barry Lefer, Elliot Atlas, Michael T. Coffey, J Walega, B Wert

Earth Sciences

Physical and chemical properties of the atmosphere at 0–8 km were measured during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiments from February to May 2000 at mid (40°–60°N) and high latitudes (60°–80°N). The observations were analyzed using a diel steady state box model to examine HOx and O3 photochemistry during the spring transition period. The radical chemistry is driven primarily by photolysis of O3 and the subsequent reaction of O(1D) and H2O, the rate of which increases rapidly during spring. Unlike in other tropospheric experiments, observed H2O2 …

Go to article

Tunable Diode Laser Measurements Of Formaldehyde During The Topse 2000 Study: Distributions, Trends, And Model Comparisons, A Fried, Yuhang Wang, C A. Cantrell, B Wert, J Walega, Brian Ridley, Elliot Atlas, R E. Shetter, Barry Lefer, Michael T. Coffey, James W. Hannigan, D R. Blake, N J. Blake, Simone Meinardi, R. Talbot, Jack E. Dibb, Eric Scheuer, Oliver Wingenter, J Snow, B J. Heikes, Dieter Ehhalt Feb 2003

Tunable Diode Laser Measurements Of Formaldehyde During The Topse 2000 Study: Distributions, Trends, And Model Comparisons, A Fried, Yuhang Wang, C A. Cantrell, B Wert, J Walega, Brian Ridley, Elliot Atlas, R E. Shetter, Barry Lefer, Michael T. Coffey, James W. Hannigan, D R. Blake, N J. Blake, Simone Meinardi, R. Talbot, Jack E. Dibb, Eric Scheuer, Oliver Wingenter, J Snow, B J. Heikes, Dieter Ehhalt

Earth Sciences

Airborne measurements of formaldehyde (CH2O) were acquired employing tunable diode laser absorption spectroscopy (TDLAS) during the 2000 Tropospheric Ozone Production About the Spring Equinox (TOPSE) study. This study consisted of seven deployments spanning the time period from 4 February to 23 May 2000 and covered a wide latitudinal band from 40°N to 85°N. The median measured CH2O concentrations, with a few exceptions, did not show any clear temporal trends from February to May in each of five altitude and three latitude bins examined. Detailed measurement–model comparisons were carried out using a variety of approaches employing two …

Go to article

Ozone, Aerosol, Potential Vorticity, And Trace Gas Trends Observed At High-Latitudes Over North America From February To May 2000, Edward V. Browell, Jonathan Hair, Carolyn Butler, William B. Grant, Russell J. Deyoung, Marta Fenn, Vincent G. Brackett, Marian B. Clayton, Lorraine A. Brasseur, David B. Harper, Brian Ridley, Andrzej Klonecki, Peter Hess, L K. Emmons, Xuexi Tie, Elliot Atlas, C A. Cantrell, Anthony Wimmers, D R. Blake, Michael T. Coffey, James W. Hannigan, Jack E. Dibb, R. Talbot, F Flocke, Andrew Weinheimer, A Fried, B Wert, J Snow, Barry Lefer Jan 2003

Ozone, Aerosol, Potential Vorticity, And Trace Gas Trends Observed At High-Latitudes Over North America From February To May 2000, Edward V. Browell, Jonathan Hair, Carolyn Butler, William B. Grant, Russell J. Deyoung, Marta Fenn, Vincent G. Brackett, Marian B. Clayton, Lorraine A. Brasseur, David B. Harper, Brian Ridley, Andrzej Klonecki, Peter Hess, L K. Emmons, Xuexi Tie, Elliot Atlas, C A. Cantrell, Anthony Wimmers, D R. Blake, Michael T. Coffey, James W. Hannigan, Jack E. Dibb, R. Talbot, F Flocke, Andrew Weinheimer, A Fried, B Wert, J Snow, Barry Lefer

Earth Sciences

Ozone (O3) and aerosol scattering ratio profiles were obtained from airborne lidar measurements on thirty-eight flights over seven deployments covering the latitudes of 40°–85°N between 4 February and 23 May 2000 as part of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) field experiment. Each deployment started from Broomfield, Colorado, with bases in Churchill, Canada, and on most deployments, Thule Air Base, Greenland. Nadir and zenith lidar O3 measurements were combined with in situ O3measurements to produce vertically continuous O3 profiles from near the surface to above the tropopause. Potential vorticity (PV) distributions …

Go to article

Near-Real-Time Measurement Of Sea-Salt Aerosol During The Seas Campaign: Comparison Of Emission-Based Sodium Detection With An Aerosol Volatility Technique, P. Campuzano-Jost, Catherine D. Clark, H. Maring, D. S. Covert, S. Howell, V. Kapustin, K. A. Clarke, E. S. Saltzman, A. J. Hynes Jan 2003

Near-Real-Time Measurement Of Sea-Salt Aerosol During The Seas Campaign: Comparison Of Emission-Based Sodium Detection With An Aerosol Volatility Technique, P. Campuzano-Jost, Catherine D. Clark, H. Maring, D. S. Covert, S. Howell, V. Kapustin, K. A. Clarke, E. S. Saltzman, A. J. Hynes

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The first deployment of an emission-based aerosol sodium detector (ASD), designed to chemically characterize marine aerosols on a near-real-time basis, is reported. Deployment occurred as part of the Shoreline Environment Aerosol Study ( SEAS) from 16 April to 1 May 2000 at Bellows Air Force Base on the east side of Oahu, where the University of Hawaii's Department of Oceanography maintains a tower for aerosol measurements. The instrument was operated in size-unsegregated mode and measurements were made that included two extended continuous sampling periods, each of which lasted for 24 h. During this time, the ASD was compared with measurements …

Go to article

Diurnal Variation In The Basal Emission Rate Of Isoprene, Jennifer L. Funk, Clive G. Jones, Christine J. Baker, Heather M. Fuller, Christian P. Giardina, Manuel T. Lerdau Jan 2003

Diurnal Variation In The Basal Emission Rate Of Isoprene, Jennifer L. Funk, Clive G. Jones, Christine J. Baker, Heather M. Fuller, Christian P. Giardina, Manuel T. Lerdau

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Isoprene is emitted from numerous plant species and profoundly influences tropospheric chemistry. Due to the short lifetime of isoprene in the atmosphere, developing an understanding of emission patterns at small time scales is essential for modeling regional atmospheric chemistry processes. Previous studies suggest that diurnal fluctuations in isoprene emission may be substantial, leading to inaccuracies in emission estimates at larger scales. We examined diurnal patterns in the basal emission rate of isoprene in red oak (Quercus rubra), eastern cottonwood (Populus deltoides), and eucalyptus (Eucalyptus saligna) and the influence of light and temperature on the magnitude of these diurnal patterns. Maximum …

Go to article

New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu Jan 2003

New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu

OES Faculty Publications

[1] New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long-speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai-Tak passed over the South China Sea (SCS). During its short 3-day stay, Kai-Tak triggered an average 30-fold increase in surface chlorophyll-a concentration. The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2-4% of SCS's annual new production. Given an average of 14 cyclones passing over the SCS annually, we suggest the long-neglected contribution of tropical cyclones to SCS's annual new production may …

Go to article

Near-Surface Currents In Desoto Canyon (1997–99): Comparison Of Current Meters, Satellite Observation, And Model Simulation, Dong-Ping Wang, Lie-Yauw Oey, Tal Ezer, Peter Hamilton Jan 2003

Near-Surface Currents In Desoto Canyon (1997–99): Comparison Of Current Meters, Satellite Observation, And Model Simulation, Dong-Ping Wang, Lie-Yauw Oey, Tal Ezer, Peter Hamilton

CCPO Publications

This study evaluates a data-assimilated model simulation of near-surface circulation in DeSoto Canyon (DSC), Gulf of Mexico, with emphasis on analyzing moored current-meter observations and comparing them with satellite data and model results. The study period is for two years from April 1997 to April 1999. The model results are from a high-resolution Gulf of Mexico model forced by analyzed wind and surface heat flux. Two types of data are used to deduce near-surface circulation: moored current meters at 13 locations in the DSC, and satellite sea level anomaly. The moored currents are mapped through multivariate objective analysis to produce …

Go to article

Assessment Of Wind Energy Potential For Eletricity Generation In Setchet, Hanang, Tanzania, A. S. Kasasi, R. M. Kainkwa Dec 2002

Assessment Of Wind Energy Potential For Eletricity Generation In Setchet, Hanang, Tanzania, A. S. Kasasi, R. M. Kainkwa

Tanzania Journal of Science

Tanzania depends heavily on hydropower for her electricity demand and experiences power shortage during the dry seasons. Wind energy is proposed as an alternative source of electricity to the fossil fuel generators during the dry season, the latter are normally used to supplement the shortfall in hydro-electricity generation. Fossil fuel generators produce emissions that are toxic and as such degrade the environment. Wind speed data from a site called Setchet is used to illustrate that the available wind energy can be harvested to generate electricity that can supplement the shortfall of electricity. The windy season, which is from July to …

Go to article

A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown Dec 2002

A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown

Publications

We use gravity wave parameters derived from the ALOHA-93 campaign to model four gravity waves in airglow emissions as observed from the ground to numerically predict whether these waves could have been observed from space. In spite of encountering critical levels, some waves may still be observed in the airglow provided the critical level lies within the airglow emission region. One of the four waves experiences a critical level in the lower region of an airglow layer such that the disturbance to the volume emission rate would be effectively limited to a short distance along a satellite line of sight. …

Go to article

A 700-Year Record Of Atmospheric Circulation Developed From The Law Dome Ice Core, East Antarctica, Joseph M. Souney Jr, Paul A. Mayewski, Ian D. Goodwin, David Meeker, Vin Morgan, Mark Aj Curran, Tas D. Van Ommen, Anne S. Palmer Nov 2002

A 700-Year Record Of Atmospheric Circulation Developed From The Law Dome Ice Core, East Antarctica, Joseph M. Souney Jr, Paul A. Mayewski, Ian D. Goodwin, David Meeker, Vin Morgan, Mark Aj Curran, Tas D. Van Ommen, Anne S. Palmer

All Materials

A 700-year, high-resolution, multivariate ice core record from Dome Summit South (DSS) (66°46′S, 112°48′E; 1370 m), Law Dome, is used to investigate sea level pressure (SLP) variability in the region of East Antarctica. Empirical orthogonal function (EOF) analysis reveals that the first EOF (LDEOF1) of the combined glaciochemical, oxygen isotope ratio, and accumulation rate record from DSS represents most of the variability in sea salt seen in the record. LDEOF1 is positively correlated (at least 95% confidence level) to instrumental June mean SLP across most of East Antarctica. Over the last 700 years, LDEOF1 levels at Law Dome were the …

Go to article

Measurements Of Pernitric Acid At The South Pole During Iscat 2000, D Slusher, L Gregory Huey, D Tanner, G Chen, D D. Davis, Martin Buhr, J Nowak, Fred Eisele, E Kosciuch, R L. Mauldin, Barry Lefer, R E. Shetter, Jack E. Dibb Nov 2002

Measurements Of Pernitric Acid At The South Pole During Iscat 2000, D Slusher, L Gregory Huey, D Tanner, G Chen, D D. Davis, Martin Buhr, J Nowak, Fred Eisele, E Kosciuch, R L. Mauldin, Barry Lefer, R E. Shetter, Jack E. Dibb

Earth Sciences

The first measurements of pernitric acid at the South Pole were performed during the second Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT 2000). Observed HO2NO2 concentrations averaged 25 pptv. Simple steady-state calculations constrained by measurements show that the lifetime of pernitric acid was largely controlled by dry deposition, with thermal decomposition becoming increasingly important at warmer temperatures. We determined that the pernitric acid equilibrium constant is less uncertain than indicated in the literature. One consequence of pernitric acid deposition to the snow surface is that it is an important sink for both NOx and HOx. Another is that …

Go to article

An Observation Of A Fast External Atmospheric Acoustic-Gravity Wave, J. H. Hecht, R. L. Walterscheid, Michael P. Hickey Ph.D., R. J. Rudy, A. Z. Liu Oct 2002

An Observation Of A Fast External Atmospheric Acoustic-Gravity Wave, J. H. Hecht, R. L. Walterscheid, Michael P. Hickey Ph.D., R. J. Rudy, A. Z. Liu

Publications

In November 1999 a new near-IR airglow imaging system was deployed at the Starfire Optical Range outside of Albuquerque, New Mexico. This system allowed wide angle images of the airglow to be collected, with high signal to noise, every 3 seconds with a one second integration time. At approximately 1000 UT on November 17, 1999, a fast wavelike disturbance was seen propagating through the OH Meinel airglow layer. This wave had an observed period of ≈215 seconds, an observed phase velocity of ≈160 m/s and a horizontal wavelength of ≈35 km. This phase velocity is among the fastest yet reported …

Go to article

Further Investigations Of A Mesospheric Inversion Layer Observed In The Aloha-93 Campaign, Tai-Yin Huang, Michael P. Hickey Ph.D., Tai-Fu Tuan Oct 2002

Further Investigations Of A Mesospheric Inversion Layer Observed In The Aloha-93 Campaign, Tai-Yin Huang, Michael P. Hickey Ph.D., Tai-Fu Tuan

Publications

Temperature and wind data obtained from a Na wind/temperature lidar operated by the University of Illinois group during the Airborne Lidar and Observations of the Hawaiian Airglow (ALOHA-93) Campaign, previously analyzed by Huang et al. [1998] using an isothermal Brunt-Va¨isa¨la¨ frequency, have been reexamined to include temperature gradients in the calculation of the Richardson number. In the previous analysis using the isothermal Brunt-Va¨isa¨la¨ frequency the existence of convective instability could not be assessed. New analysis shows that the nonisothermal Richardson number preserves some features found previously, with some striking differences noticable at times between 0900 and 1030 UT. The nonisothermal …

Go to article

Sea Level Slopes And Volume Fluxes Produced By Atmosphere Forcing In Chesapeake Bay, David Salas Monreal Oct 2002

Sea Level Slopes And Volume Fluxes Produced By Atmosphere Forcing In Chesapeake Bay, David Salas Monreal

OES Theses and Dissertations

Year long time series at eight stations in the Chesapeake Bay and inner shelf were used to determine the relative influence of wind, barometric pressure and thermosteric effects on subtidal sea level variability and slopes. Special emphasis was placed on the lower Chesapeake Bay, where inverse barometric effects accounted for up to 33% of the subtidal sea level variations and thermosteric effects accounted for less than 1 % of the variations. The greatest thermosteric influence was noted at the southernmost, saltier and shallower location (Chesapeake Bay Bridge Tunnel). Wind forcing accounted for most of this station's variability, making up more …

Go to article

High Energy Laser Pointing Through Extended Turbulence, Jason A. Tellez Sep 2002

High Energy Laser Pointing Through Extended Turbulence, Jason A. Tellez

Theses and Dissertations

The airborne laser (ABL) uses adaptive optics to compensate the atmospheric turbulence between the ABL and the target. The primary purpose of this compensation is to increase the energy density of the energy laser at the target. However, the specifics of the engagement scenario require the tracking point of reference and the adaptive optics point of reference to be located at different points on the target. This research considers the effects of tracking a target in one direction while compensating for atmospheric turbulence in a different directions. The target references used are a point source and a rectangle, while a …

Go to article

Transport Out Of The Antarctic Polar Vortex From A Three-Dimensional Transport Model, Shuhua Li, Eugene Cordero, David J. Karoly Jun 2002

Transport Out Of The Antarctic Polar Vortex From A Three-Dimensional Transport Model, Shuhua Li, Eugene Cordero, David J. Karoly

Faculty Publications, Meteorology and Climate Science

[1] A three-dimensional chemical transport model is utilized to study the transport out of the Antarctic polar vortex during the southern hemisphere spring. On average, over five consecutive years between 1993 and 1997, horizontal transport out of the vortex into the midlatitude stratosphere is smaller than vertical transport into the troposphere. However, there is significant interannual variability in the magnitude of mass exchange, which is related to year-to-year fluctuations in planetary wave activity. In 1994 the net loss of the vortex tracer mass in September is similar to that in October. However, the relative mass flux entering the midlatitude stratosphere …

Go to article

Studies Of Peroxyacetyl Nitrate (Pan) And Its Interaction With The Snowpack At Summit, Greenland, Kevin M. Ford, Bradley M. Campbell, P B. Shepson, Steven B. Bertman, R E. Honrath, Matthew C. Peterson, Jack E. Dibb May 2002

Studies Of Peroxyacetyl Nitrate (Pan) And Its Interaction With The Snowpack At Summit, Greenland, Kevin M. Ford, Bradley M. Campbell, P B. Shepson, Steven B. Bertman, R E. Honrath, Matthew C. Peterson, Jack E. Dibb

Earth Sciences

Peroxyacetyl nitrate (PAN) was measured in ambient and snowpack interstitial air at Summit, Greenland, in June and July of 1998 and 1999 and at a rural/forest site in the Keewenaw Peninsula of Michigan in January of 1999. At Summit, we found that PAN typically represented between 30 and 60% of NOy. In the summer of 1999, a significant diel variation in both PAN/NOy and NOx/NOy was observed, but this was much less pronounced in 1998. Experiments during SNOW99 near Houghton, Michigan, indicated that PAN undergoes weak uptake onto snow grain surfaces. At Summit, we …

Go to article

Shouldn’T Snowpacks Be Sources Of Monocarboxylic Acids?, Jack E. Dibb, Matthew Arsenault May 2002

Shouldn’T Snowpacks Be Sources Of Monocarboxylic Acids?, Jack E. Dibb, Matthew Arsenault

Earth Sciences

We report the first measurements of the mixing ratios of acetic (CH3COOH) and formic (HCOOH) acids in the air filling the pore spaces of the snowpacks (firn air) at Summit, Greenland and South Pole. Both monocarboxylic acids were present at levels well above 1 ppbv throughout the upper 35 cm of the snowpack at Summit. Maximum mixing ratios in Summit firn air reached nearly 8 ppbv CH3COOH and 6 ppbv HCOOH. At South Pole the mixing ratios of these acids in the top 35 cm of firn air were also generally >1 ppbv, though their maximums …

Go to article

An Examination Of Anomalously Low Column Ozone In The Southern Hemisphere Midlatitudes During 1997, Eugene C. Cordero, Terrence R. Nathan Apr 2002

An Examination Of Anomalously Low Column Ozone In The Southern Hemisphere Midlatitudes During 1997, Eugene C. Cordero, Terrence R. Nathan

Faculty Publications, Meteorology and Climate Science

[1] Observations from both ground-based and satellite instruments show record low column ozone abundance between 20°S and 40°S during 1997. The 1997 monthly averaged column ozone from the Total Ozone Mapping Spectrometer (TOMS) is up to 25 Dobson units (DU) lower than the TOMS climatological mean (1979–1996) and up to 20 DU below the previous record low values. Observations from the Halogen Occultation Experiment show that below average ozone concentrations during 1997 were confined primarily to the lower stratosphere. Residual circulation statistics calculated from the United Kingdom Meteorological Office temperature analyses indicate that circulation anomalies during 1997 can account for …

Go to article

Near-Real-Time Applications Of A Mesoscale Analysis System To Complex Terrain, Steven M. Lazarus, Carol M. Ciliberti, John D. Horel, Keith A. Brewer Mar 2002

Near-Real-Time Applications Of A Mesoscale Analysis System To Complex Terrain, Steven M. Lazarus, Carol M. Ciliberti, John D. Horel, Keith A. Brewer

Aeronautics Faculty Publications

Several mesoscale data analysis systems are reviewed, of which one is then adapted and applied to the complex terrain of northwest Utah and the western United States. The analysis system relies on the simple, but computationally efficient, successive correction methodology. Near-real-time three-dimensional mesoscale analyses are produced hourly over northwest Utah at 1-km horizontal resolution while analyses are produced every 15 min for surface fields over northwest Utah and the western United States. Surface analyses over the western United States are also generated at 0000 and 1200 UTC to help to initialize 36- h mesoscale model forecasts. Comparisons between the 1-km …

Go to article

Extratropical Transition Of Southwest Pacific Tropical Cyclones. Part I: Climatology And Mean Structure Changes, Mark R. Sinclair Mar 2002

Extratropical Transition Of Southwest Pacific Tropical Cyclones. Part I: Climatology And Mean Structure Changes, Mark R. Sinclair

Applied Aviation Sciences - Prescott

A database of tropical cyclone best track and intensity information for the southwest Pacific Ocean basin is used to construct a 28-year climatology for tropical cyclones that move into middle latitudes. Of the nine or so tropicalcyclones that form each year, an average of about three can be expected to migrate south of 35°S, with the greatest fraction in March. Storms entering the Tasman Sea west of New Zealand (NZ) move almost due south on average and retain greater intensity than those to the east of NZ, where storms decay quickly while moving rapidly away to the southeast. Storms east …

Go to article

Airborne Sampling Of Aerosol Particles: Comparison Between Surface Sampling At Christmas Island And P-3 Sampling During Pem-Tropics B, Jack E. Dibb, R. Talbot, Garry Seid, C. E. Jordan, Eric Scheuer, Elliot Atlas, Nicola J. Blake, D R. Blake Jan 2002

Airborne Sampling Of Aerosol Particles: Comparison Between Surface Sampling At Christmas Island And P-3 Sampling During Pem-Tropics B, Jack E. Dibb, R. Talbot, Garry Seid, C. E. Jordan, Eric Scheuer, Elliot Atlas, Nicola J. Blake, D R. Blake

Earth Sciences

Bulk aerosol sampling of soluble ionic compounds from the NASA Wallops Island P-3 aircraft and a tower on Christmas Island during PEM-Tropics B provides an opportunity to assess the magnitude of particle losses in the University of New Hampshire airborne bulk aerosol sampling system. We find that most aerosol-associated ions decrease strongly with height above the sea surface, making direct comparisons between mixing ratios at 30 m on the tower and the lowest flight level of the P-3 (150 m) open to interpretation. Theoretical considerations suggest that vertical gradients of sea-salt aerosol particles should show exponential decreases with height. Observed …

Go to article

Is The Ozone Hole Over Your Classroom?, Eugene Cordero Jan 2002

Is The Ozone Hole Over Your Classroom?, Eugene Cordero

Faculty Publications, Meteorology and Climate Science

First year university science students are surveyed about their understanding of the ozone layer, ozone depletion and the effect of ozone depletion on Australia. Although students seem to understand the basic function of the ozone layer, over 65% of students incorrectly believe that the ozone hole is over Australia, and over 90% of students incorrectly believe that the ozone hole is present during the summer. Together these ideas seem to explain why nearly 75% of students blame the ozone hole for Australia’s high rate of skin cancer. Survey results also indicate that students seem confused about global warming, and the …

Go to article

First Prev Next Last