Bibliography

Geomagnetic storm-induced plasma density enhancements in the southern polar ionospheric region: A comparative study using St. Patrick s Day storms of 2013 and 2015

order to examine if the variations in the TEC were caused by thermospheric composition changes in the southern high-latitude regions, we present O/N 2 maps obtained from the GUVI

Shreedevi, PR; Choudhary, RK; Thampi, Smitha; Yadav, Sneha; Pant, TK; Yu, Yiqun; McGranaghan, Ryan; Thomas, Evan; Bhardwaj, Anil; Sinha, AK;

Published by: Space Weather      Published on:

YEAR: 2020     DOI: 10.1029/2019SW002383

Morphological study on the ionospheric variability at Bharati, a polar cusp station in the southern hemisphere

Morphological features of the quiet/disturbed time variations in the Total Electron Content (TEC) at the polar cusp station Bharati (76.69\textdegreeS MLAT) during a period of 5 years starting from February 2013 to December 2017 has been studied using GPS TEC measurements. The TEC at Bharati follows a diurnal pattern with its peak appearing close to local noon/magnetic noon during the summer/winter months. A nighttime enhancement in the TEC is seen around the magnetic midnight during winter. The plasma density at Bharati also exhibits semi-annual variation and a strong dependence on solar activity. A comparison of the IRI 2016 model derived TEC and the GPS TEC at Bharati shows significant differences with large underestimation of TEC especially during the nighttime period of the winter months. A two fold difference in magnitude between the GPS and modeled TEC is also observed in the summer months of the high solar activity period of 2013\textendash2015. The response of the TEC to geomagnetic storms is found to depend on the onset time of the storm. We show that the morphological features in the temporal evolution of the plasma density at Bharati vary as the location of Bharati changes from being inside the polar cap, to the auroral region, and to the polar cusp in quick succession in a day. Our results highlight the fact that the dynamic nature of the location of Bharati with respect to the position of the polar cap plays an important role in deciding the plasma distribution at the polar cusp station.

Shreedevi, P.R.; Choudhary, R.K.; Yu, Yiqun; Thomas, Evan;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 10/2019

YEAR: 2019     DOI: 10.1016/j.jastp.2019.105058

Evaluation of Space Traffic Effects in SBUV Polar Mesospheric Cloud Data

Water-rich rocket exhaust plumes, in particular those emitted by the National Aeronautics and Space Administration Space Shuttle, have been suggested to make a significant contribution to long-term trends in polar mesospheric cloud (PMC) ice water content. We investigate this claim using the combined Solar Backscatter Ultraviolet (SBUV) PMC data record from eight separate instruments, which includes 60 Shuttle launches during PMC seasons between 1985 and 2011. No statistically significant postlaunch signal in PMC total ice is observed based on superposed epoch analysis of the SBUV record. Only a few launches show individual peaks in total ice anomaly above the seasonal background that exceed an empirical threshold, and the maximum cumulative signature from these infrequent cases is typically less than 5\% of the season total in ice mass. Other non-Shuttle launches show circumstantial evidence of possible PMC effects, although supporting evidence for plume transport is not available. We conclude that space traffic effects have been a negligible component of long-term PMC behavior.

DeLand, Matthew; Thomas, Gary;

Published by: Journal of Geophysical Research: Atmospheres      Published on: 03/2019

YEAR: 2019     DOI: 10.1029/2018JD029756

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

The Super Dual Auroral Radar Network (SuperDARN) is a network of high-frequency (HF) radars located in the high- and mid-latitude regions of both hemispheres that is operated under international cooperation. The network was originally designed for monitoring the dynamics of the ionosphere and upper atmosphere in the high-latitude regions. However, over the last approximately 15 years, SuperDARN has expanded into the mid-latitude regions. With radar coverage that now extends continuously from auroral to sub-auroral and mid-latitudes, a wide variety of new scientific findings have been obtained. In this paper, the background of mid-latitude SuperDARN is presented at first. Then, the accomplishments made with mid-latitude SuperDARN radars are reviewed in five specified scientific and technical areas: convection, ionospheric irregularities, HF propagation analysis, ion-neutral interactions, and magnetohydrodynamic (MHD) waves. Finally, the present status of mid-latitude SuperDARN is updated and directions for future research are discussed.

Nishitani, Nozomu; Ruohoniemi, John; Lester, Mark; Baker, Joseph; Koustov, Alexandre; Shepherd, Simon; Chisham, Gareth; Hori, Tomoaki; Thomas, Evan; Makarevich, Roman; , others;

Published by: Progress in Earth and Planetary Science      Published on:

YEAR: 2019     DOI: 10.1186/s40645-019-0270-5

GPS phase scintillation at high latitudes during two geomagnetic storms

Prikryl, Paul; Ghoddousi-Fard, Reza; Ruohoniemi, John; Thomas, Evan; Zhang, Y; Paxton, LJ;

Published by: Auroral dynamics and space weather      Published on:

YEAR: 2015     DOI: