Bibliography

Features of the Ionospheric Storm on December 21--24, 2016

The purpose of this work is to investigate the response of the F region and topside ionosphere to the moderate geomagnetic storm on December 21, 2016 (Kp max = 6). The subject of the study is the height–time variations in the parameters of the ionospheric plasma over Kharkiv. Experimental data were obtained using vertical sounding and incoherent scatter methods by the ionosonde and incoherent scatter radar. The presented results are based on the correlation analysis of the incoherent scattered signal. The ion and electron temperatures, as well as the ionospheric plasma velocity, were determined from a set of measured correlation functions of the incoherently scattered signal. The electron density was calculated using the following parameters measured for a number of ionospheric heights: power of the incoherent scatter signal, ion and electron temperatures, and the electron density at the ionospheric F2 layer peak, which is calculated from the critical frequency measured by the ionosonde. The moderate geomagnetic storm was accompanied by an ionospheric storm over Kharkiv with sign-variable phases (first positive and second negative). The peak increase in the electron density was 1.8 times and decrease was 3.4 times. The negative phase was accompanied by a slight rise of the F2 layer (by 20–28 km), which could be due to a decrease in the vertical component of the plasma velocity and an increase in the electron temperature by 600–800 K and ion temperature by 100–160 K. Effects of strong negative ionospheric disturbances were registered during the subsequent magnetospheric disturbance of December 22–24, 2016, with a decrease in electron density at the F2 layer peak up to 2.5–4.9 times. The effects of negative disturbances manifested themselves in the variations of temperatures of electrons and ions. In general, the moderate magnetic storm caused significant changes in the electron density in the ionospheric F2 layer peak, which were accompanied by heating of the ionospheric plasma as well as changes in variations of the vertical component of the ionospheric plasma velocity and the height of ionization during the main phase of the magnetic storm.

Katsko, S.; Emelyanov, Ya.; Chernogor, L.;

Published by: Kinematics and Physics of Celestial Bodies      Published on: mar

YEAR: 2021     DOI: 10.3103/S0884591321020045

geomagnetic storm; Electron density; Ionospheric storm; space weather; ionosonde; electron and ion temperatures; incoherent scatter radar; plasma velocity; positive and negative storm phases

An Unusually Large Electron Temperature Increase Over Arecibo Associated With an Intense Geomagnetic Storm

We present an investigation of the F-region electron temperature to an intense geomagnetic storm that occurred on 5 August 2011. The investigation is based on the incoherent scatter radar measurements at Arecibo Observatory, Puerto Rico (18.3°N, 66.7°W). The electron temperature exhibits a rapid and intensive enhancement after the commencement of the geomagnetic storm. The electron temperature increases by ∼800 K within an hour, which is seldomly reported at Arecibo. At the same time, a depletion of the electron density is also observed. The daytime perturbations of electron density and temperature are anticorrelated with the correlation coefficient, which is −0.88 and −0.91 on the day and the following day of the geomagnetic storm, respectively. According to the Global Ultraviolet Imager measurements, the ratio of atomic oxygen to molecular nitrogen concentration () decreases dramatically during the storm. Our analysis suggests that the enhancement of the electron temperature is due to the depletion of the electron density, which is likely associated with the decrease of . The reduction of maybe caused by a prompt upward plasma motion after the commencement of the geomagnetic storm.

Lv, Xiedong; Gong, Yun; Zhang, ShaoDong; Zhou, Qihou; Ma, Zheng;

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

YEAR: 2021     DOI: 10.1029/2021JA029836

Arecibo; F-region electron temperature; geomagnetic storm; incoherent scatter radar

Long-term ionospheric cooling: Dependency on local time, season, solar activity, and geomagnetic activity

Ionospheric ion temperature Ti is an excellent approximation to neutral temperature Tn in the thermosphere, especially for altitudes below 300 km. This analysis of long-term Ti trends in the F region over different local times is based on a database of incoherent scatter radar (ISR) observations spanning more than three solar cycles during 1968\textendash2006 at Millstone Hill and represents an extended effort to a prior study focusing on noon-time only. This study provides important information for understanding the difference between the ISR and other results. A gross average of the Ti trend at heights of Ti \~ Tn (200\textendash350 km) is \~ -4 K/decade, a cooling trend close to the Tn estimation based on the satellite neutral density data. However, there exists considerable variability in the cooling: it is strong during the day and very weak during the night with a large apparent warming at low altitudes (200\textendash350 km); it is strong at solar minimum for both daytime and nighttime. The strongest cooling for altitudes below 375 km occurs around 90\textendash120 solar flux units of the 10.7 cm solar flux, not at the lowest solar flux. There appears more cooling toward high magnetic activity, but this dependency is very weak. No consistent and substantial seasonal dependency across different heights was found. We speculate that a fraction of the observed cooling trend may be contributed by a gradual shifting away from the sub-auroral region at Millstone Hill, as part of the secular change in the Earth\textquoterights magnetic field. In this 39 year long series of data record, two anomalous Ti drops were noticed, and we speculate on their connection to volcano eruptions in 1982 and 1991.

Zhang, Shun-Rong; Holt, John;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50306

global change; incoherent scatter radar; ionospheric temperature; long-term trend; Millstone Hill

Global model comparison with Millstone Hill during September 2005

A direct comparison between simulation results from the Global Ionosphere Thermosphere Model (GITM) and measurements from the Millstone Hill incoherent scatter radar (ISR) during the month of September 2005 is presented. Electron density, electron temperature, and ion temperature results are compared at two altitudes where ISR data is the most abundant. The model results are produced, first using GITM running in one dimension, which allows comparison at the Millstone Hill location throughout the entire month. The model results have errors ranging from 20\% to 50\% over the course of the month. In addition, the F2 peak electron density (NmF2) and height of the peak (HmF2) are compared for the month. On average the model indicates higher peak electron densities as well as a higher HmF2. During the time period from 9 September through 13 September, the trends in the data are different than the trends in the model results. These differences are due to active solar and geomagnetic conditions during this time period. Three-dimensional (3-D) GITM results are presented during these active conditions, and it is found that the 3-D model results replicate the trends in the data more closely. GITM is able to capture the positive storm phase that occurred late on 10 September but has the most difficulty capturing the density depletion on 11 and 12 September that is seen in the data. This is probably a result of the use of statistical high-latitude and solar drivers that are not as accurate during storm time.

Pawlowski, David; Ridley, Aaron; Kim, Insung; Bernstein, Dennis;

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

YEAR: 2008     DOI: https://doi.org/10.1029/2007JA012390

Ionosphere; model; incoherent scatter radar

Comparison of the first long-duration IS experiment measurements over Millstone Hill and EISCAT Svalbard radar with IRI2001

The first long-duration incoherent scatter (IS) radar observations over Millstone Hill (42.6°N, 288.5°E) and EISCAT Svalbard radar (ESR, 78.15°N, 16.05°E) from October 4 to November 4, 2002 are compared with the newly updated version of the IRI model (IRI2001). The present study showed that: (1) For the peak parameters hmF2 and foF2, the IRI results are in good agreement with the observations over Millstone Hill, but there are large discrepancies over ESR. For the B parameters, the table option of IRI produces closer values to the observed ones with respect to the Gulyaeva’s option. (2) When the observed F2 peak parameters are used as input of IRI, the IRI model produces the reasonably results for the bottomside profiles during daytime over Millstone Hill, while it gives a lower bottomside density during nighttime over Millstone Hill and the whole day over ESR than what is observed experimentally. Moreover, IRI tends to overestimate the topside Ne profiles at both locations. (3) The Ti profiles of IRI can generally reproduce the observed values, whereas the IRI-produced Te profiles show large discrepancies with the observations. Overall comparative studies reveal that the agreement between the IRI predictions and experimental values is better over Millstone Hill than that over ESR.

Lei, Jiuhou; Liu, Libo; Wan, Weixing; Zhang, Shun-Rong; Van Eyken, A.P.;

Published by: Advances in Space Research      Published on:

YEAR: 2006     DOI: https://doi.org/10.1016/j.asr.2005.01.061

Ionosphere; incoherent scatter radar; Modelling and forecasting; International reference ionosphere