Bibliography

Investigation of sudden electron density depletions observed in the dusk sector by the Poker Flat, Alaska incoherent scatter radar in summer

This paper investigates unusually deep and sudden electron density depletions (troughs) observed in the Poker Flat (Alaska) Incoherent Scatter Radar data in middle summer of 2007 and 2008. The troughs were observed in the premidnight sector during periods of weak magnetic and solar activity. The density recovered to normal levels around midnight. At the time when the electron density was undergoing its steep decrease, there was usually a surge of the order of 100 to 400 K in the ion temperature that lasted less than 1 h. The Ti surges were usually related to similar surges in the AE index, indicating that the high-latitude convection pattern was expanding and intensifying at the time of the steep electron density drop. The convection patterns from the Super Dual Auroral Radar Network also indicate that the density troughs were associated with the expansion of the convection pattern to Poker Flat. The sudden decreases in the electron density are difficult to explain in summer because the high-latitude region remains sunlit for most of the day. This paper suggests that the summer density troughs result from lower latitude plasma that had initially been corotating in darkness for several hours post sunset and brought back toward the sunlit side as the convection pattern expanded. The magnetic declination of ~22\textdegree east at 300 km at Poker Flat greatly facilitates the contrast between the plasma convecting from lower latitudes and the plasma that follows the high-latitude convection pattern.

Richards, P.; Nicolls, M.; St.-Maurice, J.-P.; Goodwin, L.; Ruohoniemi, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.1210.1002/2014JA020541

ion temperature; plasma convection; plasma troughs

Global observations of E region plasma density morphology and variability

Nicolls, Michael; Rodrigues, Fabiano; Bust, Gary;

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

YEAR: 2012     DOI: 10.1029/2011JA017069

Ionospheric and thermospheric variations associated with prompt penetration electric fields

Lu, G.; Goncharenko, L.; Nicolls, M.; Maute, A.; Coster, A.; Paxton, L.;

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

YEAR: 2012     DOI: 10.1029/2012JA017769

Global observations of E region plasma density morphology and variability

The global morphology and variability of the ionospheric E region plasma density are estimated from satellite-based radio occultation total electron content (ROTEC) measurements. Vertical profiles of E region electron density are estimated using the inversion technique recently proposed by Nicolls et al. (2009). In this technique, the F-region contribution to each ROTEC measurement is removed using an assimilative model of the ionosphere in order to mitigate the effects of F-region gradients in the estimation of E region profiles. The technique is applied to occultation observations made by GPS receivers onboard COSMIC satellites aided by F-region electron density specification provided by the Ionospheric Data Assimilation Four-Dimensional (IDA4D) algorithm. Global estimates of hmE, NmE, and E region total electron content (TEC) are presented for two different months: April 2007 and January 2008. Results of our analysis show that ROTEC measurements such as those provided by the COSMIC constellation can produce reasonable and valuable estimates of E region parameters on a global scale when properly treated for the effect of F-region density gradients. The agreement between the α-Chapman theory of ionization and recombination and estimated profiles is demonstrated. Reasonable estimates of E region variability can also be specified by the global measurements. The dependence of the E region variability on latitude is quantified and presented.

Nicolls, Michael; Rodrigues, Fabiano; Bust, Gary;

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

YEAR: 2012     DOI: https://doi.org/10.1029/2011JA017069

E region electron density; E region morphology; E region variability; radio occultation

Radar, lidar, and optical observations in the polar summer mesosphere shortly after a space shuttle launch

Kelley, M.; Nicolls, M.; Varney, R.; Collins, R.; Doe, R.; Plane, J.; Thayer, J.; Taylor, M.; Thurairajah, B.; Mizutani, K.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2010

YEAR: 2010     DOI: 10.1029/2009JA014938

Space Shuttle Impacts on Mesospheric Clouds and Iron Layers as Observed by Lidars and Satellites in the Antarctic and Arctic

Chu, X; Collins, RL; Stevens, MH; Plane, JM; Meier, RR; Deland, MT; Kelley, MC; Nicolls, MJ; Thurairajah, B; Varney, RH; , others;

Published by:       Published on:

YEAR: 2009     DOI:

Estimating E region density profiles from radio occultation measurements assisted by IDA4D

Nicolls, MJ; Rodrigues, FS; Bust, GS; Chau, JL;

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

YEAR: 2009     DOI:

Observations of ionospheric heating during the passage of solar coronal hole fast streams

Sojka, Jan; McPherron, RL; Van Eyken, AP; Nicolls, MJ; Heinselman, CJ; Kelly, JD;

Published by: Geophysical research letters      Published on:

YEAR: 2009     DOI:

Measured and modeled ionospheric densities, temperatures, and winds during the international polar year

Richards, PG; Nicolls, MJ; Heinselman, CJ; Sojka, JJ; Holt, JM; Meier, RR;

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

YEAR: 2009     DOI:

Radar and Airglow Studies of F-Region composition and Dynamics at low latitudes

This thesis presents a series of studies investigating the composition and dynamics of the low latitude F-region ionosphere using airglow imagers and the Arecibo and Jicamarca incoherent scatter radars (ISRs), along with supporting instrumentation. Some dynamical aspects of the low latitude ionosphere are investigated. The effects of a large-scale traveling ionospheric disturbance (TID) are studied. The TID characteristics are consistent with an atmospheric disturbance caused by high latitude Lorentz forcing associated with periodic substorms. Plasmaspheric coupling is necessary to explain the observed electron densities and airglow intensities.

Nicolls, Michael;

Published by:       Published on:

YEAR: 2006     DOI:

Study of the Pre-Reversal Enhancement at the Jicamarca Radio Observatory using the ASPEN-TIMEGCM

Makela, JJ; Crowley, G; Kelley, MC; Nicolls, MJ; Kudeki, E; Chau, JL;

Published by:       Published on:

YEAR: 2003     DOI: