Bibliography

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Found 125 entries in the Bibliography.

Showing entries from 101 through 125

2008

Longitudinal variations of electron temperature and total ion density in the sunset equatorial topside ionosphere

Based on the DMSP F13 Satellite observations from 1995 to 2005, the longitudinal distributions of the electron temperature (Te) and total ion density (Ni) in the sunset equatorial topside ionosphere are examined. The results suggest that the longitudinal variations of both Te and Ni exhibit obvious seasonal dependence as follows: (1) wavenumber-four longitudinal structure in equinox, (2) three peaks structure in June solstice, and (3) two peaks structure in December solstice. Moreover, the longitudinal variations of Te and Ni show significant anti-correlation, and we speculate that the longitudinal variation of Te may result from that of Ni which can control Te through the electron cooling rate. The wavenumber-four longitudinal structures of both Te and Ni in equinox may relate to the eastward propagating zonal wavenumber-3 diurnal tide (DE3), which has effect on the amplitude of the daytime zonal electric field. The longitudinal variation of Te and Ni in the two solstices may be caused both by longitudinal variation of geomagnetic declination and DE3.

Ren, Zhipeng; Wan, Weixing; Liu, Libo; Zhao, Biqiang; Wei, Yong; Yue, Xinan; Heelis, Roderick;

Published by: Geophysical Research Letters Published on:

YEAR: 2008 DOI: https://doi.org/10.1029/2007GL032998

topside ionosphere; longitudinal variation

Anomalous enhancement of ionospheric electron content in the Asian-Australian region during a geomagnetically quiet day

Zhao, B; Wan, W; Liu, L; Igarashi, K; Nakamura, M; Paxton, LJ; Su, S-Y; Li, G; Ren, Z;

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

YEAR: 2008 DOI:

A data-model comparative study of ionospheric positive storm phase in the midlatitude F region

Lu, G; Goncharenko, LP; Coster, AJ; Richmond, AD; Roble, RG; Aponte, N; Paxton, LJ;

Published by: Published on:

YEAR: 2008 DOI:

2007

Ionospheric disturbances during the severe magnetic storm of November 7\textendash10, 2004

Grigorenko, E.; Lysenko, V.; Pazyura, S.; Taran, V.; Chernogor, L.;

Published by: Geomagnetism and Aeronomy Published on: Jan-12-2007

YEAR: 2007 DOI: 10.1134/S0016793207060059

A statistical analysis of longitudinal dependences of upper thermospheric zonal winds at dip equator latitudes derived from CHAMP

Haüsler, K.; Lühr, H.; Rentz, S.; Köhler, W.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-08-2007

YEAR: 2007 DOI: 10.1016/j.jastp.2007.04.004

Features of annual and semiannual variations derived from the global ionospheric maps of total electron content

Zhao, B.; Wan, W.; Liu, L.; Mao, T.; Ren, Z.; Wang, M.; Christensen, A.;

Published by: Annales Geophysicae Published on: Jan-01-2007

YEAR: 2007 DOI: 10.5194/angeo-25-2513-2007

Observations of a positive storm phase on September 10, 2005

In this study, we present multi-instrument observations of a strong positive phase of ionospheric storm, which occurred on September 10, 2005 during a moderate geomagnetic storm with minimum D_st=-60\ nT and maximum K_p=6\textendash. The daytime electron density measured by the Millstone Hill incoherent scatter radar (42.6\textdegreeN, 288.5\textdegreeE) increased after 13\ UT (\~8\ LT) compared with that before the storm. This increase is observed throughout the daytime, lasts for about 9\ h, and covers F-region altitudes above \~230\ km. At the altitude of 300\ km, the maximum increase in N_e reaches a factor of 3 by 19:30\textendash20:00\ UT and is accompanied by a \~1000\ K decrease in electron temperature, a \~100\textendash150\ K increase in ion temperature, and a strong upward drift. Observations by Arecibo ISR (18.3\textdegreeN, 293.3\textdegreeE) reveal similar features, with the maximum increase in electron density reaching a factor of 2.5 at 21:30\ UT, i.e. 1.5\textendash2\ h later than over Millstone Hill. The GPS TEC data show that the increase in electron density observed at Millstone Hill and Arecibo is only a part of a global picture reflected in TEC. The increase in TEC reaches a factor of 2 and covers middle and low latitudes at 19\ UT. At later times this increase moves to lower latitudes. A combination of mechanisms were involved in generation of positive phase. The penetration electric field resulted in N_e enhancements at subauroral and middle latitudes, the TAD/TID played an important role at middle and lower latitudes, and increase in O/N₂ ratio could contribute to the observed positive phase at middle and lower latitudes. The results show the importance of an upward vertical drift at \~140\textendash250\ km altitude, which is observed for sustained period of time and assists in the convergence of ionization into the F-region.

Goncharenko, L.P.; Foster, J.C.; Coster, A.J.; Huang, C.; Aponte, N.; Paxton, L.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2007

YEAR: 2007 DOI: 10.1016/j.jastp.2006.09.011

F-region; geomagnetic storm; Ionosphere; positive phase

Ionospheric disturbances during the severe magnetic storm of November 7—10, 2004

Grigorenko, EI; Lysenko, VN; Pazyura, SA; Taran, VI; Chernogor, LF;

Published by: Geomagnetism and Aeronomy Published on:

YEAR: 2007 DOI:

Atomic oxygen photoionization rates computed with high resolution cross sections and solar fluxes

Meier, RR; McLaughlin, Brendan; Warren, HP; Bishop, James;

Published by: Geophysical research letters Published on:

YEAR: 2007 DOI:

2006

Large variations in the thermosphere and ionosphere during minor geomagnetic disturbances in April 2002 and their association with IMF B _y

We investigate the variations in the thermosphere and ionosphere using multi-instrument observations during the April 2002 period, with a particular focus on periods during small geomagnetic disturbances. Large and long-lasting reductions in the daytime electron density were observed at midlatitudes by incoherent scatter radars, ionosondes, and GPS receivers. These reductions reached 30\textendash50\% and were observed over an extended longitudinal area. They propagated to middle latitudes (35\textendash40\textdegreeN) in the case of a weak geomagnetic disturbance (K_p = 3-) and to low latitudes (0\textendash10\textdegreeN) in the case of a stronger disturbance (K_p = 5-). Data from the GUVI instrument aboard the TIMED satellite reveal a reduction in the daytime O/N₂ ratio in the coincident area. Similar decreases are also predicted by the TIMEGCM/ASPEN model in both O/N₂ ratio and electron density, though the magnitude of the decrease from the model is smaller than observed. We suggest that these ionospheric and thermospheric disturbances result from high-latitude energy input and efficient transport of regions with reduced O/N₂ to lower latitudes. We discuss the possible role of a strong positive B_y component of the interplanetary magnetic field in the transport of regions with reduced O/N₂.

Goncharenko, L.; Salah, J.; Crowley, G.; Paxton, L.; Zhang, Y.; Coster, A.; Rideout, W.; Huang, C.; Zhang, S.; Reinisch, B.; Taran, V.;

Published by: Journal of Geophysical Research Published on: 03/2006

YEAR: 2006 DOI: 10.1029/2004JA010683

Electron density; thermospheric composition; thermospheric wind

Photoionization Rate of Atomic Oxygen

Meier, RR; McLaughlin, BM; Warren, HP; Bishop, J;

Published by: Published on:

YEAR: 2006 DOI:

Large variations in the thermosphere and ionosphere during minor geomagnetic disturbances in April 2002 and their association with IMF By

Goncharenko, L; Salah, J; Crowley, G; Paxton, LJ; Zhang, Y; Coster, A; Rideout, W; Huang, C; Zhang, S; Reinisch, B; , others;

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

YEAR: 2006 DOI:

2005

October 2002 30-day incoherent scatter radar experiments at Millstone Hill and Svalbard and simultaneous GUVI/TIMED observations

A long-duration incoherent scatter radar (ISR) experiment was conducted at Millstone Hill and Svalbard from October 4\textendashNovember 4, 2002. Along with the simultaneous GUVI/TIMED neutral composition measurements, this 30-day run enabled us to study a number of thermosphere-ionosphere-magnetosphere phenomena. This paper focuses on the day-to-day variability and quasiperiodic oscillation of the ionosphere. The day-to-day variability under quiet magnetic conditions in electron density Ne, ion temperature Ti and electron temperature Te, respectively, changed with local time and height, with the largest variability in Ne and the smallest in Ti. Midnight through dawn was the period of largest variability. Quasiperiodic Ne oscillations were present with periods \>1 day. Some of these oscillations were correlated with changes in the neutral composition originating from geomagnetic activity, which altered the global atmospheric circulation as a result of high latitude heating processes as indicated in Svalbard ion temperature enhancements. However, the wave-type oscillation of Ne exhibits a downward phase progression which persists up to 600 km and prevails until a large storm appears to impose an upward phase progression.

Zhang, Shun-Rong; Holt, John; Erickson, Phil; Lind, Frank; Foster, John; van Eyken, Anthony; Zhang, Yongliang; Paxton, Larry; Rideout, William; Goncharenko, Larisa; Campbell, Glenn;

Published by: Geophysical Research Letters Published on: 01/2005

YEAR: 2005 DOI: 10.1029/2004GL020732

Space Sciences-L01108 October 2002 30-day incoherent scatter radar experiments at Millstone Hill and Svalbard and simultaneous GUVI/TIMED observations (DOI 10.1029/2004GL020732)

Zhang, Shun-Rong; Holt, John; Erickson, Phil; Lind, Frank; Foster, John; van Eyken, Anthony; Zhang, Yongliang; Paxton, Larry; Rideout, William; Goncharenko, Larisa; , others;

Published by: Geophysical Research Letters Published on:

YEAR: 2005 DOI:

Shun-Rong Zhang, John M. Holt, Phil J. Erickson, Frank D. Lind, John C. Foster, Anthony P. van Eyken, 2 Yongliang Zhang, 3 Larry J. Paxton, 3 William C. Rideout

Goncharenko, Larisa; Campbell, Glenn;

Published by: GEOPHYSICAL RESEARCH LETTERS Published on:

YEAR: 2005 DOI:

2004

Retrievals of nighttime electron density from Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission Global Ultraviolet Imager (GUVI) measurements

In this work we will present a method for retrieving nighttime electron density profiles from OI 135.6 nm limb emissions measured by the Global Ultraviolet Imager (GUVI) aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission spacecraft. The primary mechanism for 135.6 nm radiance in the nighttime thermosphere is recombination of O⁺ ions, and the volume emission rate is approximately proportional to the square of the electron density. Herein we describe a two-step inversion method in which we first determine the volume emission rate as a function of altitude from the radiance measurements and then use the inferred volume emission rates to determine the electron density profile. There are two important factors that we have addressed in constructing the retrieval algorithms for this problem. First, the GUVI instrument was primarily designed for day side measurements. Consequently, the signal levels on the night side are very low, and our retrieval algorithms must therefore be able to function in regions where the signals are weak. Second, since we must take the square root of the volume emission rate, it must be everywhere positive in order for the electron density to be deduced. For this reason, we have imposed nonnegativity constraints (using the methods described by Menke [1989]) on what might otherwise be discrete linear retrievals of volume emission rate. After describing the retrieval method we present an error analysis and a preliminary comparison with coincident measurements by incoherent scatter radars (ISRs). In general, the retrieved electron densities from the GUVI data agree well with the ISR data, although more coincident measurements would increase our confidence in the resulting electron density profiles.

DeMajistre, R.; Paxton, L.; Morrison, D.; Yee, J.-H.; Goncharenko, L.; Christensen, A.;

Published by: Journal of Geophysical Research Published on: 04/2004

YEAR: 2004 DOI: 10.1029/2003JA010296

Electron density; inversion; low-latitude ionosphere; TIMED/GUVI

Retrievals of nighttime electron density from TIMED Global Ultraviolet Imager (GUVI) measurements

DeMajistre, R; Paxton, LJ; Morrison, D; Yee, JH; Goncharenko, L; Christensen, A;

Published by: J. Geophys. Res Published on:

YEAR: 2004 DOI:

Ionosphere and Upper Atmosphere-A 05305. Retrievals of nighttime electron density from Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission Global Ultraviolet Imager (GUVI)

DeMajistre, R; Paxton, LJ; Morrison, D; Yee, JH; Goncharenko, LP; Christensen, AB;

Published by: Journal of Geophysical Research-Part A-Space Physics Published on:

YEAR: 2004 DOI: