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- Climatology (2)
- F region (2)
- Ionosphere (2)
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- Airglow wave (1)
- Assimilation ionosphere model (1)
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- Cachoeira Paulista (1)
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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
Effects Of A Large Mesospheric Temperature Enhancement On The Hydroxyl Rotational Temperature As Observedfrom The Ground, S. M.L. Melo, R. P. Lowe, W. R. Pendleton Jr., Michael J. Taylor, B. Williams, C. Y. She
Effects Of A Large Mesospheric Temperature Enhancement On The Hydroxyl Rotational Temperature As Observedfrom The Ground, S. M.L. Melo, R. P. Lowe, W. R. Pendleton Jr., Michael J. Taylor, B. Williams, C. Y. She
All Physics Faculty Publications
The rotational temperature obtained from the rotational population distribution in the bands of the hydroxyl airglow has been shown to be a suitable proxy for the temperature at a height of 87 km [She and Lowe, 1998]. In this paper we examine in detail simultaneous observations on November 2–3, 1997, at Fort Collins, Colorado (41°N, 105°W), with both a sodium temperature lidar and the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) OH mesospheric temperature mapper during which significant differences between the hydroxyl and lidar temperatures occur. The large differences are associated with a major temperature enhancement in the region …
Climatology Of Mid- And Low-Latitude F Region Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, C. G. Fesen, G. G. Shepherd, B. H. Solheim
Climatology Of Mid- And Low-Latitude F Region Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, C. G. Fesen, G. G. Shepherd, B. H. Solheim
Bela G. Fejer
No abstract provided.
An Unusual Airglow Waveevent Observed At Cachoeira Paulista 23°S, A. F. Medeiros, Michael J. Taylor, H. Takahashi, P. P. Batista, D. Gobbi
An Unusual Airglow Waveevent Observed At Cachoeira Paulista 23°S, A. F. Medeiros, Michael J. Taylor, H. Takahashi, P. P. Batista, D. Gobbi
All Physics Faculty Publications
An all-sky CCD airglow imager has been used to obtain a wealth of data on the MLT airglow emissions from Cachoeira Paulista, Brazil (22.7° S, 45.0° W). Measurements of the NIR OH, OI(557.7 nm), O2(0,1) and the thermospheric OI(630.0 nm) emissions have been made since October 1998. In addition, simultaneous measurements of the airglow zenith intensities and rotational temperatures, and vertical wind structure between 80 and 100 km were made using a co-located multi-channel photometer and a meteor radar. On the night of July 13, 1999, the CCD images showed active wave events exhibiting a variety of short period wave …
Multiplewavelength Optical Observations Of A Long-Lived Meteor Trail, B. R. Clemesha, A. F. Medeiros, D. Gobbi, H. Takahashi, P. P. Batista, Michael J. Taylor
Multiplewavelength Optical Observations Of A Long-Lived Meteor Trail, B. R. Clemesha, A. F. Medeiros, D. Gobbi, H. Takahashi, P. P. Batista, Michael J. Taylor
All Physics Faculty Publications
A long‐lived meteor trail has been observed at wavelengths of 572.5 nm, 557.7 nm, 630.0 nm, 865.5 nm and in the near infrared band from 715 to 930 nm. The trail was detected at all these wavelengths, with the possible exception of 865.5 nm, where its identification was marginal. It was seen longest (17 minutes) through the wide band NIR 715‐930 nm filter. The fact that the trail was only marginally visible in the 865.5 nm (0–1) band of molecular oxygen, and was strongest in the wide‐band NIR image, raises serious doubts about an earlier suggestion that the infrared light …
Mesospheric Planetary Waves Atnorthern Hemisphere Fall Equinox, H. L. Liu, R. G. Roble, Michael J. Taylor, W. R. Pendleton Jr.
Mesospheric Planetary Waves Atnorthern Hemisphere Fall Equinox, H. L. Liu, R. G. Roble, Michael J. Taylor, W. R. Pendleton Jr.
All Physics Faculty Publications
Northern hemisphere planetary waves are strong in the winter and weak in the summer, and they go through a fast transition around equinox. This transition is studied here using NCAR Thermosphere‐Ionosphere‐Mesosphere‐Electrodynamics general circulation model (TIME‐GCM) simulations with 1997 National Centers for Environmental Prediction (NCEP) analysis. The planetary wave variability during the transition and its effect on the temperature and winds in the mesosphere are examined. The simulated planetary wave structure agrees with climatological studies, and the fast transition of the planetary waves is captured by the model. The wave variability produces large temperature changes in the upper atmosphere above local …
Large Amplitude Perturbations In Mesospheric Oh Meinel And 87-Km Na Lidar Temperatures Around The Autumnal Equinox, Michael J. Taylor, W. R. Pendleton Jr., H. L. Liu, C. Y. She, Larry Gardner, R. G. Roble, V. Vasoli
Large Amplitude Perturbations In Mesospheric Oh Meinel And 87-Km Na Lidar Temperatures Around The Autumnal Equinox, Michael J. Taylor, W. R. Pendleton Jr., H. L. Liu, C. Y. She, Larry Gardner, R. G. Roble, V. Vasoli
All Physics Faculty Publications
Two high‐precision CEDAR instruments, an OH Mesospheric Temperature Mapper (MTM) and a Na Temperature Lidar, have been used to investigate seasonal variability in the mid‐latitude temperature at ∼87 km altitude over the western USA. Here we report the observation of a large perturbation in mesospheric temperature that occurs shortly after the autumnal equinox in close association with the penetration of planetary‐wave energy from the troposphere into the mesosphere. This perturbation has been observed on three occasions and exhibits a departure of up to ∼25–30 K from the nominal seasonal trend during a disturbed period of ∼2 weeks. Such behavior represents …
Climatology Of Upper Thermospheric Daytime Neutral Winds From Satellite Observations, John T. Emmert
Climatology Of Upper Thermospheric Daytime Neutral Winds From Satellite Observations, John T. Emmert
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
We studied the global climatology of mid- and low-latitude F region daytime neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS). Quiet-time winds are mostly poleward and westward during the day, and are generally 5-20 m/s smaller in the longitudinal sector closest to the magnetic pole, compared to longitudinally averaged winds. The pre-noon zonal winds are less westward with increasing solar flux, while the post-noon meridional winds are less poleward. Our quiet-time results are in good agreement with the NCAR Thermosphere-Ionosphere- Electrodynamics General Circulation Model (TIEGCM).
We computed residual …
Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson
Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Snapover is particularly relevant to Earth-orbiting spacecraft powered by high-voltage solar arrays. During snapover, the current collected by a positively biased conductor that is immersed in a plasma suddenly increases when two conditions are met: i) there is an immediately adjacent insulator; ii) the conductor exceeds a positive threshold voltage with respect to the plasma. The enhanced current develops as a consequence of the insulator, either through secondary electron (SE) emission or by material ionization. Experiments were performed to examine snapover onset potential and current collection dependence on conductor and insulator materials, conductor size and shape, sample history, biasing rate, …
The Vacuum Excitation And Squeezing Properties Of Two Quantum Oscillators With Delta-Kicked Interactions, J Y. Ji, David Peak
The Vacuum Excitation And Squeezing Properties Of Two Quantum Oscillators With Delta-Kicked Interactions, J Y. Ji, David Peak
All Physics Faculty Publications
The vacuum excitation and squeezing of two harmonic oscillators with delta-kicked interactions for four types of elementary coupling are studied. The exact quantum motion for the Heisenberg operators and the explicit form of squeezing operators are found. The variances are calculated to study the squeezing properties for position, momentum and generalized quadrature operators.
Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith
Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith
All Physics Faculty Publications
A fully nonlinear modal analysis identifies a critical centerline wave number qc for river meandering that separates long-wavelength bends, which grow to cutoff, from short-wavelength bends, which decay. Exact, numerical, and approximate analytical results for qc rely on the Ikeda, Parker, and Sawai [J. Fluid Mech. 112, 363 (1981)] model, supplemented by dynamical equations that govern the river migration and length. Predictions also include upvalley bend migration at long times and a peak in lateral migration rates at intermediate times. Experimental tests are suggested.
Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto
Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto
Bela G. Fejer
We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the …
Seasonal And Magnetic Activity Variations Of Ionospheric Electric Fields Above The Southernmid-Latitude Station, Bundoora, Australia, M. L. Parkinson, R. Polglase, Bela G. Fejer, L. Scherliess, P. L. Dyson, S. M. Ujmaia
Seasonal And Magnetic Activity Variations Of Ionospheric Electric Fields Above The Southernmid-Latitude Station, Bundoora, Australia, M. L. Parkinson, R. Polglase, Bela G. Fejer, L. Scherliess, P. L. Dyson, S. M. Ujmaia
Bela G. Fejer
We investigate the seasonal, local solar time, and geomagnetic activity variations of the average Doppler velocity measured by an HF digital ionosonde deployed at Bundoora, Australia. The Doppler velocities were heavily averaged to suppress the short-term effects (<3>hours) of atmospheric gravity waves, and thereby obtain the diurnal variations attributed to the tidally-driven ionospheric dynamo and electric fields generated by magnetic disturbances. The observed seasonal variations in Doppler velocity were probably controlled by variations in the lower thermospheric winds and ionospheric conductivity above Bundoora and in the magnetically conjugate location. The diurnal variations of the meridional (fieldperpendicular) drifts and their …3>
The Lunar Tide In The Equatorial F Region Vertical Ion Drift Velocity, R. J. Stening, Bela G. Fejer
The Lunar Tide In The Equatorial F Region Vertical Ion Drift Velocity, R. J. Stening, Bela G. Fejer
Bela G. Fejer
Vertical ion drift velocity data from Jicamarca have been analyzed for a lunar semidiurnal tide using a least squares fitting method. Amplitudes of up to 6 m s−1 are obtained with phases in agreement with lunar tidal determinations of other associated physical parameters. Variations between season, solar activity, and day to night are also examined. Generally, amplitudes are larger in the southern summer. Much of the phase variation with season is very similar for solar maximum and minimum years. There is a summer to winter phase change that is most distinct at solar maximum nighttime. A day-to-night phase reversal can …
Space Missions To Detect The Cosmic Gravitational-Wave Background, Neil J. Cornish, Shane L. Larson
Space Missions To Detect The Cosmic Gravitational-Wave Background, Neil J. Cornish, Shane L. Larson
All Physics Faculty Publications
It is thought that a stochastic background of gravitational waves was produced during the formation of the universe. A great deal could be learned by measuring this Cosmic Gravitational-wave Background (CGB), but detecting theCGB presents a significant technological challenge. The signal strength is expected to be extremely weak, and there will be competition from unresolved astrophysical foregrounds such as white dwarf binaries. Our goal is to identify the most promising approach to detect the CGB. We study the sensitivities that can be reached using both individual, and cross-correlated pairs of space based interferometers. Our main result is a general, coordinate …
Mesospheric Temperature Observationsat The Usu / Cass Atmospheric Lidar Observatory (Alo), Vincent B. Wickwar, T D. Wilkerson, M Hammond, Joshua P. Herron
Mesospheric Temperature Observationsat The Usu / Cass Atmospheric Lidar Observatory (Alo), Vincent B. Wickwar, T D. Wilkerson, M Hammond, Joshua P. Herron
All Physics Faculty Publications
The Center for Atmospheric and Space Sciences (CASS) at Utah State University (USU) operates the ALO for studying the middle atmosphere from the stratosphere to the lower thermosphere. ALO’s mid-latitude location (41.74°N, 111.81°W, 1466 m) is very unique in that it is in the middle of an extensive set of rugged mountains, the Rocky Mountains, which are a major orographic source of gravity waves that may give rise to a longitudinal variation in the mesospheric structure. Mesospheric observations between approximately 45 and 90 km have been carried out on many clear nights with the ALO Rayleigh- scatter lidar since late …
Group Invariant Solutions In Mathematical Physics And Differential Geometry, Ian M. Anderson, Mark E. Fels, Charles G. Torre
Group Invariant Solutions In Mathematical Physics And Differential Geometry, Ian M. Anderson, Mark E. Fels, Charles G. Torre
All Physics Faculty Publications
This is a brief overview of our work on the theory of group invariant solutions to differential equations. The motivations and applications of this work stem from problems in differential geometry and relativistic field theory. The key feature in our theory is that we allow for non-transverse symmetry group actions, which are very common in applications.
Retrieval And Validation Of Mesospheric Temperatures From Wind Imaging Interferometer Observations, M G. Shepherd, B Reid, S Zhang, B H. Solheim, G G. Shepherd, Vincent B. Wickwar, Joshua P. Herron
Retrieval And Validation Of Mesospheric Temperatures From Wind Imaging Interferometer Observations, M G. Shepherd, B Reid, S Zhang, B H. Solheim, G G. Shepherd, Vincent B. Wickwar, Joshua P. Herron
All Physics Faculty Publications
A method has been developed for the retrieval of mesospheric temperatures in the 65–90 km altitude range from satellite observations made by the Wind Imaging Interferometer (WINDII) aboard the Upper Atmosphere Research Satellite (UARS). Retrieved temperatures are derived from Rayleigh scattered sunlight observed in a wavelength band centered at 553 nm. Integrated line-of-sight radiance observations are inverted to tangent height volume scattering profiles, which are proportional to atmospheric density. From these, absolute temperature profiles are calculated using a technique derived from established Rayleigh lidar retrieval methods assuming that the atmosphere is in hydrostatic equilibrium and that it obeys the ideal …
Assimilation Ionosphere Model: Development And Testing With Combined Ionospheric Campaign Caribbean Measurements, Jan Josef Sojka, D. C. Thompson, Robert W. Schunk, T. W. Bullett, J. J. Makela
Assimilation Ionosphere Model: Development And Testing With Combined Ionospheric Campaign Caribbean Measurements, Jan Josef Sojka, D. C. Thompson, Robert W. Schunk, T. W. Bullett, J. J. Makela
All Physics Faculty Publications
Assimilation Ionosphere Model (AIM) is a physics-based, global, ionospheric specification model that is currently under development. It assimilates a diverse set of real-time (or near-real-time) measurements, such as ionograms, GPS slant total electron content (TEC), and in situ plasma measurements. This study focuses on a middle latitude ionosonde assimilation capability in both local and regional forms. The models described are capable of using theƒ0 F 2 and h m F 2 from ionograms to generate either a local or a regional distribution of the induced plasma drift. This induced drift is usually caused by the meridional neutral wind. Results …
Gps Normalization And Preliminary Modeling Results Of Total Electron Content During A Midlatitude Space Weather Event, J. J. Makela, M. C. Kelley, Jan Josef Sojka, X. Pi, A. J. Mannucci
Gps Normalization And Preliminary Modeling Results Of Total Electron Content During A Midlatitude Space Weather Event, J. J. Makela, M. C. Kelley, Jan Josef Sojka, X. Pi, A. J. Mannucci
All Physics Faculty Publications
On November 22–23, 1997, a geomagnetic storm occurred during a period of excellent viewing conditions over the Arecibo Observatory in Puerto Rico. Here we explore the total electron content (TEC) registered by Global Positioning System (GPS) receivers located close to the Cornell All-Sky Imager (CASI) at the Arecibo Observatory. The storm began with the equatorward surge of a very high (100% increase) TEC enhancement stretching for many hours of local time on the dayside. At dusk the TEC over the Caribbean remained elevated with levels equal to the noontime monthly averages. During the event the TEC was highly structured and …