Bibliography

Notice:

Clicking on the title will open a new window with all details of the bibliographic entry.
Clicking on the DOI link will open a new window with the original bibliographic entry from the publisher.
Clicking on a single author will show all publications by the selected author.
Clicking on a single keyword, will show all publications by the selected keyword.

Found 20 entries in the Bibliography.

Showing entries from 1 through 20

2019

The Low-Latitude Ionosphere/Thermosphere Enhancements in Density (LLITED) Mission

Bishop, Rebecca; Walterscheid, Richard; Clemmons, James; Barjatya, Aroh; Gunter, Liam;

Published by: Published on:

YEAR: 2019 DOI:

2018

Observations of Spatial Variations in O/N ₂ During an Auroral Substorm Using the Multichannel Downlooking Camera on the VISIONS Rocket

At 0821 UT on 7 February 2013, during an auroral substorm, the NASA VISIONS rocket was launched northward from Poker Flat Research Range on a flight to approximately 750-km altitude that terminated in the Arctic Ocean. A subpayload jettisoned on the up leg carried a multichannel optical imager that looked downward and observed the auroral emission through four narrow passband filters. Three of the channels had sufficiently strong signal to allow a measure of the time evolution of the horizontal extent of the electron aurora and changes in the ratio of the column O to the column N₂. These data revealed rather rapid changes in this measure of composition over an area larger than would be expected from the changes expected from particle and Joule heating. Although such rapid large changes have been observed previously, and Christensen et al. (1997, https://doi.org/10.1029/97JA01800) had hypothesized that they were due to enhanced turbulent diffusion, this imaging experiment is the first to show their evolution over a large area. On the down leg the camera was able to see the vertical spatial extent of the auroral emission which is consistent with the decrease in O/N₂ seen in the downlooking data. The change in this ratio with altitude suggests the deposition of an additional number of low-energy electrons that would cause a larger decrease in that ratio at higher altitudes.

Hecht, J.; Clemmons, J.; Conde, M.; Hampton, D.; Michell, R.; Rowland, D.; Pfaff, R.; Walterscheid, R.;

Published by: Journal of Geophysical Research: Space Physics Published on: 07/2018

YEAR: 2018 DOI: 10.1029/2018JA025288

2015

Thermal cell structures in the high-latitude thermosphere induced by ion drag

Walterscheid, RL; Crowley, G;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2015 DOI:

2013

Rapid, highly structured meridional winds and their modulation by non migrating tides: Measurements from the Streak mission

[1]\ Measurements of the Earth\textquoterights low latitude thermosphere returned by the ionization gauge on the Streak mission are reported and discussed. The measurements are of the amount of gas rammed into the sensor by its passage through the thermospheric medium. They were obtained in the dusk sector in the altitude range 130\textendash330 km and are shown to be strongly structured by the geomagnetic field. Similarities to the structure of the equatorial ionization anomaly are discussed. The structure is interpreted as being due to rapid (several hundred meters per second) meridional winds having an antisymmetric pattern with respect to the geomagnetic equator. The measurements are interpreted in light of results from other missions and are shown to fit well with ideas based on complementary measurements from the Dynamics Explorer 2 mission discussed as the Equatorial Temperature and Wind Anomaly. Several features of these winds are described and discussed, including their altitude dependence, how they form convection cells that extend to high latitude, and how the wind amplitudes vary with geographic longitude with an apparent wavenumber one variation. The latter characteristic is shown to be consistent with being the signature of tidal variations observed by others. Approximate calculations utilizing published values for the pertinent parameters are used to show that heating from the dissipation due to ion drag within the ionospheric F region is a dominant driver of the inferred winds.

Clemmons, J.; Walterscheid, R.; Christensen, A.; Bishop, R.;

Published by: Journal of Geophysical Research: Space Physics Published on: 02/2013

YEAR: 2013 DOI: 10.1029/2012JA017661

2012

A multiyear (2002--2006) climatology of O/N2 in the lower thermosphere from TIMED GUVI and ground-based photometer observations

Hecht, J.; Mulligan, T.; Correira, J.; Clemmons, J.; Strickland, D.; Walterscheid, R.; Conde, M.;

Published by: Journal of Geophysical Research Published on: Jan-01-2012

YEAR: 2012 DOI: 10.1029/2011JA017146

2009

Large-scale instabilities of the lower thermosphere during an active period

Walterscheid, RL; Crowley, G;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2009 DOI:

2008

Paired Ionosphere-Thermosphere Orbiters (PITO): Science and Implementation

Nigg, DA; Clemmons, JH; Walterscheid, RL; Jolly, R;

Published by: Americal Geophysical Union, Fall Published on:

YEAR: 2008 DOI:

2005

Orbital Drag-Atmospheric Density Concept of Operations2004 Update

The Global UV Imager (GUVI), a predecessor instrument to SSUSI, has shown promising, though limited, comparison to orbit-based densities. Current operations at the SCC rely on

Buell, Diane; Walterscheid, Richard; Marcos, Frank; Fuller-Rowell, Tim; Picone, J; Storz, Mark; Owens, Jerry;

Published by: Published on:

YEAR: 2005 DOI:

2004

Quiet-time seasonal behavior of the thermosphere seen in the far ultraviolet dayglow

The TIMED/GUVI instrument is a far ultraviolet spectrograph that obtains images in five spectrally resolved wavelength channels. These images yield information on the dayside composition, temperature, solar EUV flux, large-scale wave structures, and auroral processes. In this paper we present an overview analysis of Earth-disk images for four seasons (March, July, and September 2002 and January 2003). Days were selected during geomagnetically quiet periods when the Sun was nearly in the orbital plane (noon orbits). Two of GUVI\textquoterights five channels (designated as 135.6 and LBH_S and dominated by OI 135.6 nm and short wavelength N₂ LBH band emission, respectively) are used when the instrument is in its imaging mode. These data are used to derive O/N₂ (column density ratio referenced to an N₂ column density of 10¹⁷ cm^-2). The AURIC model is used to generate a lookup table that relates O/N₂ to the ratio of 135.6 to LBH_S for a given solar zenith angle. Global images of derived O/N₂ (designated as GUVI O/N₂) are presented for the 4 days. The initial validation of the retrieved composition ratio comes from comparison with the NRLMSIS model. Good overall qualitative agreement is obtained between GUVI and NRLMSIS. Both data and model exhibit similar latitudinal behaviors on the near-solstice days, namely a distinct gradient with O/N₂ decreasing from the winter to the summer hemisphere. Reductions in O/N₂ in the vicinity of magnetic poles are seen in both GUVI and NRLMSIS images. Globally, O/N₂ is smaller at the solstices and may be explained by the \textquotedblleftthermospheric spoon\textquotedblright mechanism discussed by Fuller-Rowell [1998]. Alternatively, the greater overall values at the equinoxes may arise in part from global response to greater Joule heating at these times of the year. The sensitivity of O/N₂ to scalings of the N₂ LBH cross section and solar EUV below 20 nm is also addressed in response to recent papers on these topics. This initial look at the GUVI data demonstrates great promise of FUV remote sensing as a way to observe thermospheric composition changes over broad geographic scales.

Strickland, D.; Meier, R.; Walterscheid, R.; Christensen, A.; Paxton, L.; Morrison, D.; Craven, J.; Crowley, G.;

Published by: Journal of Geophysical Research Published on: 01/2004

YEAR: 2004 DOI: 10.1029/2003JA010220

far ultraviolet; remote sensing; seasonal behavior; thermosphere

Solar EUV irradiance variability derived from terrestrial far ultraviolet dayglow observations

Remotely sensed ultraviolet emissions from the Earth s upper atmosphere are shown to mirror fluctuations in solar EUV irradiance during July 2002, including the overall increase and decrease as the Sun rotated, and episodic increases associated with multiple solar flares. The TIMED/GUVI dayglow observations are used to derive a new quantity, QEUVGUVI, which is a measure of integrated solar EUV electromagnetic energy shortward of 45 nm. Both the absolute QEUVGUVI values and their modulation by solar rotation agree well with the corresponding solar EUV energy estimated by the NRLEUV irradiance variability model. The QEUVGUVI values do not support recent suggestions that the solar EUV irradiances estimated by the model of Hinteregger et al. be increased by a factor of four, nor even a factor of two.

Strickland, D.J.; Lean, J.L.; Meier, R.R.; Christensen, A.B.; Paxton, L.J.; Morrison, D.; Craven, J.D.; Walterscheid, R.L.; Judge, D.L.; McMullin, D.R.;

Published by: Geophysical research letters Published on:

YEAR: 2004 DOI: 10.1029/2003GL018415

2003

The Sun-Earth Connection as Viewed from GUVI on TIMED

Paxton, L; Christensen, A; Avery, S; Craven, J; Crowley, G; Meier, R; Meng, C; Srickland, D; Swenson, C; Walterscheid, R; , others;