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Articles 1 - 13 of 13
Full-Text Articles in Physics
Mid-Latitude Climatologies Of Mesospheric Temperature And Geophysical Temperature Variability Determined With The Rayleigh-Scatter Lidar At Alo-Usu, Joshua P. Herron, Vincent B. Wickwar
Mid-Latitude Climatologies Of Mesospheric Temperature And Geophysical Temperature Variability Determined With The Rayleigh-Scatter Lidar At Alo-Usu, Joshua P. Herron, Vincent B. Wickwar
All Physics Faculty Publications
From 1993-2004, 839 nights were observed with the Rayleigh-scatter lidar at Utah State University’s Atmospheric Lidar Observatory. They were reduced to obtain nighttime mesospheric temperatures between 45 and ~90 km, which were then combined to derive composite annual climatologies of mid-latitude temperatures and geophysical temperature variability. At 45 km, near the stratopause, there is a ~250 K temperature minimum in mid-winter and a 273 K maximum in mid-May. The variability behaves oppositely, being 7-10 K in winter and 2.5 K in summer. At 85 km, there is a 215 K temperature maximum at the end of December and a 170 …
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
All Physics Faculty Publications
There are relatively few instruments that have the capabilities to make near continuous measurements of the mesosphere-lower-thermosphere (MLT) region. Rayleigh scatter and resonance lidars, particularly sodium resonance lidar, have been the two dominant ground-based techniques for acquiring mesosphere and MLT vertical temperature profiles, respectively, for more than two decades. With these measurements, the dynamics (gravity waves, tides) and long-term temperature trends (upper atmosphere cooling) of the MLT region can be studied. The Utah State University (USU; 41.7º N, 111.8º W) campus hosts a unique upper atmospheric observatory which houses both a high-power, large-aperture Rayleigh lidar and a sodium resonance Doppler …
Ensemble Modeling With Data Assimilation Models: A New Strategy For Space Weather Specifications, Forecasts, And Science, Robert W. Schunk, Ludger Scherliess, V. Eccles, Larry Gardner, Jan Josef Sojka, L. Zhu, X. Pi, A. J. Mannucci, B. D. Wilson, A. Komjathy, C, Wang, G. Rosen
Ensemble Modeling With Data Assimilation Models: A New Strategy For Space Weather Specifications, Forecasts, And Science, Robert W. Schunk, Ludger Scherliess, V. Eccles, Larry Gardner, Jan Josef Sojka, L. Zhu, X. Pi, A. J. Mannucci, B. D. Wilson, A. Komjathy, C, Wang, G. Rosen
All Physics Faculty Publications
The Earth’s Ionosphere-Thermosphere-Electrodynamics (I-T-E) system varies markedly on a range of spatial and temporal scales and these variations have adverse effects on human operations and systems, including high-frequency communications, over-the-horizon radars, and survey and navigation systems that use Global Positioning System (GPS) satellites. Consequently, there is a need to elucidate the underlying physical pro- cesses that lead to space weather disturbances and to both mitigate and forecast near-Earth space weather.
Ionospheric Ion Temperature Forecasting In Multiples Of 27 Days, Jan Josef Sojka, Robert W. Schunk, Michael J. Nicholls
Ionospheric Ion Temperature Forecasting In Multiples Of 27 Days, Jan Josef Sojka, Robert W. Schunk, Michael J. Nicholls
All Physics Faculty Publications
he ionospheric variability found at auroral locations is usually assumed to be unpredictable. The magnetosphere, which drives this ionospheric variability via storms and substorms, is at best only qualitatively describable. In this study we demonstrate that over a 3 year period, ionospheric variability observed from Poker Flat, Alaska, has, in fact, a high degree of long-term predictability. The observations used in this study are (a) the solar wind high speed stream velocity measured by the NASA Advanced Composition Explorer satellite, used to define the corotating interaction region (CIR), and (b) the ion temperature at 300 km altitude measured by the …
Coordinated Investigation Of Midlatitude Upper Mesospheric Temperature Inversion Layers And The Associated Gravity Wave Forcing By Na Lidar And Advanced Mesospheric Temperature Mapper In Logan, Utah, Tao Yuan, Pierre-Dominique Pautet, Y. Zhao, Xuguang Cai, Michael J. Taylor, Neal R. Criddle
Coordinated Investigation Of Midlatitude Upper Mesospheric Temperature Inversion Layers And The Associated Gravity Wave Forcing By Na Lidar And Advanced Mesospheric Temperature Mapper In Logan, Utah, Tao Yuan, Pierre-Dominique Pautet, Y. Zhao, Xuguang Cai, Michael J. Taylor, Neal R. Criddle
All Physics Faculty Publications
Mesospheric inversion layers (MIL) are well studied in the literature but their relationship to the dynamic feature associated with the breaking of atmospheric waves in the mesosphere/lower thermosphere (MLT) region are not well understood. Two strong MIL events (ΔT ~30 K) were observed above 90 km during a 6 day full diurnal cycle Na lidar campaign conducted from 6 August to 13 August Logan, Utah (42°N, 112°W). Colocated Advanced Mesospheric Temperature Mapper observations provided key information on concurrent gravity wave (GW) events and their characteristics during the nighttime observations. The study found both MILs were well correlated with the development …
Modeling The Ionospheric E And F1 Regions: Using Sdo-Eve Observations As The Solar Irradiance Driver, Jan Josef Sojka, Joseph B. Jensen, Michael David, Robert W. Schunk, Tom Woods, Frank Eparvier
Modeling The Ionospheric E And F1 Regions: Using Sdo-Eve Observations As The Solar Irradiance Driver, Jan Josef Sojka, Joseph B. Jensen, Michael David, Robert W. Schunk, Tom Woods, Frank Eparvier
All Physics Faculty Publications
Over the altitude range of 90–150 km, in dayside nonauroral regions, ionization is controlled almost entirely by solar ultraviolet irradiance; the response time for ionization during solar exposure is almost instantaneous, and likewise, the time scale for recombination into neutral species is very fast when the photoionizing source is removed. Therefore, if high-resolution solar spectral data are available, along with accurate ionization cross sections as a function of wavelength, it should be possible to model this ionospheric region with greater accuracy. The Extreme Ultraviolet Variability Experiment (EVE) instrument on the National Aeronautics and Space Administration Solar Dynamics Observatory (SDO) satellite, …
Ionospheric Induced Scintillation: A Space Weather Enigma, Jan Josef Sojka
Ionospheric Induced Scintillation: A Space Weather Enigma, Jan Josef Sojka
All Physics Faculty Publications
The effect of scintillation on radio signals whose propagation path involves the Earth’s ionosphere is analogous to the allies of World War II receiving radio messages that had passed through the Enigma machine. In both these cases, man-made information has been encrypted and transmitted via radio. The two encryption methods are shown in Figure 1. The right panel shows a World War II Enigma machine used extensively by German U-boats to convey encrypted messages transmitted by radio [Perera, 2010]. The left panel gives an extreme example of a mapping of ionospheric irregularities at 3 m, which creates very severe scintillation …
Coordinated Investigation Of Summer Time Mid-Latitude Descending E Layer (Es) Perturbations Using Na Lidar, Ionosonde, And Meteor Wind Radar Observations Over Logan, Utah (41.7°N, 111.8°W), Tao Yuan, Chad Fish, Jan Josef Sojka, D. Rice
Coordinated Investigation Of Summer Time Mid-Latitude Descending E Layer (Es) Perturbations Using Na Lidar, Ionosonde, And Meteor Wind Radar Observations Over Logan, Utah (41.7°N, 111.8°W), Tao Yuan, Chad Fish, Jan Josef Sojka, D. Rice
All Physics Faculty Publications
It is well known that there is a strong correlation between the formation of a descending sporadic E layer (Es) and the occurrence of large upper atmospheric zonal wind shears, most likely driven by solar thermal tides and/or gravity waves. We present new results of Esperturbation events captured between 13 and 17 July 2011 (UT days 194–198) as part of a coordinated campaign using a wind/temperature Na lidar at Utah State University [41.7ºN, 111.8°W], and a Canadian Advanced Digital Ionosonde (CADI; Scientific Instrumentation Ltd., Saskatoon, Saskatchewan, Canada) and SkiYMet meteor wind radar, both located at nearby …
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
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 …
Observations Of A Noctilucent Cloud Above Logan, Utah (41.7°N, 111.8°W) In 1995, Joshua P. Herron, Vincent B. Wickwar, P J. Espy, J W. Merriwether
Observations Of A Noctilucent Cloud Above Logan, Utah (41.7°N, 111.8°W) In 1995, Joshua P. Herron, Vincent B. Wickwar, P J. Espy, J W. Merriwether
All Physics Faculty Publications
A Rayleigh-scatter lidar has been operated at the Atmospheric Lidar Observatory (ALO) on the Utah State University (USU) campus (41.7°N, 111.8°W) since August 1993. During the morning of 22 June 1995, lidar returns from a noctilucent cloud (NLC) were observed for approximately 1 hr, well away from the twilight periods when NLCs are visible. This detection of an NLC at this latitude shows that the first reported sighting, in 1999 (Wickwar et al., 2002), was not a unique occurrence. This 1995 observation differs from the 1999 one in that temperatures could be deduced. Near the 83-km NLC altitude the temperatures …
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 …
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 …
Winds In The Upper Mesosphere At Mid-Latitude: First Results Using An Imaging Fabry-Perot Interferometer, D Rees, A Aruliah, T J. Fuller-Rowell, Vincent B. Wickwar, R J. Sica
Winds In The Upper Mesosphere At Mid-Latitude: First Results Using An Imaging Fabry-Perot Interferometer, D Rees, A Aruliah, T J. Fuller-Rowell, Vincent B. Wickwar, R J. Sica
All Physics Faculty Publications
The first stage of a new midlatitude facility at the Hardware Ranch Observatory near Bear Lake (41.93°N, 111.42°W, 1970 M elevation), for studies of the aeronomy of the middle and upper atmosphere, was completed during early September 1989. An Imaging Fabry‐Perot interferometer (IFPI) (Rees et al., 1982; Rees et al., 1990), was commissioned with a special Imaging Photon Detector (IPD) (McWhirter et al., 1982), equipped with a Gallium Arsenide (GaAs) photocathode. Wind and temperature structure can be deduced from observations of the Doppler shift and Doppler broadening of airglow and auroral emissions from the mesosphere and thermosphere. The near infra‐red …