scholarly journals Analysis of Ionospheric foF2 by Solar Activity over the Korean Peninsula

2016 ◽  
Vol 6 (1) ◽  
pp. 71
Author(s):  
Min-Ho Jeon ◽  
Chang-Heon Oh
Keyword(s):  
Solar Activity ◽  
Standard Deviation ◽  
Sea Level ◽  
Critical Frequency ◽  
High Electron ◽  
High Electron Density ◽  
Layer Height ◽  
Annual Variations ◽  
F Region ◽  
The Mean

The F2 layer is the upper sector of the ionospheric F region, and it is ~250 km above sea level. It has a high electron density and thus plays an important role in shortwave communications. The variations of the critical frequency of the F2 layer (foF2) offer clues regarding the events happening within the entire F2 layer, and foF2 analysis is essential for stable shortwave communications. This study analyzes the seasonal and annual variations of the foF2 as well as the reactions of the F2 layer height at two locations in South Korea by employing the mean and standard deviation (SD) used in previous studies. To ensure a more elaborate analysis, the median and quartiles were used for analyzing the ionosphere. We thereby compensate for the limitations of the mean and SD in developing the SD, despite the convenience of the SD for probability analysis. The application of the median and quartiles for the analysis of ionospheric data led to analysis results with greater detail. This was achieved by determining the relative SD and concurrently displaying the outliers and range of variations

Analysis of Ionospheric foF2 by Solar Activity over the Korean Peninsula

2016 ◽  
Vol 6 (1) ◽  
pp. 71
Author(s):  
Min-Ho Jeon ◽  
Chang-Heon Oh
Keyword(s):  
Solar Activity ◽  
Standard Deviation ◽  
Sea Level ◽  
Critical Frequency ◽  
High Electron ◽  
High Electron Density ◽  
Layer Height ◽  
Annual Variations ◽  
F Region ◽  
The Mean

The F2 layer is the upper sector of the ionospheric F region, and it is ~250 km above sea level. It has a high electron density and thus plays an important role in shortwave communications. The variations of the critical frequency of the F2 layer (foF2) offer clues regarding the events happening within the entire F2 layer, and foF2 analysis is essential for stable shortwave communications. This study analyzes the seasonal and annual variations of the foF2 as well as the reactions of the F2 layer height at two locations in South Korea by employing the mean and standard deviation (SD) used in previous studies. To ensure a more elaborate analysis, the median and quartiles were used for analyzing the ionosphere. We thereby compensate for the limitations of the mean and SD in developing the SD, despite the convenience of the SD for probability analysis. The application of the median and quartiles for the analysis of ionospheric data led to analysis results with greater detail. This was achieved by determining the relative SD and concurrently displaying the outliers and range of variations

scholarly journals On the relation between ionospheric parameters and sunspot number

2020 ◽  
Vol 1 ◽  
Author(s):  
Chris Hall ◽  
Magnar Gullikstad Johnsen
Keyword(s):  
Solar Activity ◽  
Change Point ◽  
Critical Frequency ◽  
Auroral Oval ◽  
Change Points ◽  
Observation Site ◽  
F Region ◽  
Critical Frequency Fof2 ◽  
E Region ◽  
The Relationship

AbstractIn a recent study, mid-latitude ionospheric parameters were compared with solar activity; it was suggested that the relationship between these, earlier assumed stable, might be changing with time (Lastovicka, 2019). Here, the information is extended to higher latitude (69.6°N, 19.2E) and further back in time. For the ionospheric F-region (viz. the critical frequency, FoF2) the same behaviour is seen with a change-point around 1996. For the ionospheric E-region (viz. the critical frequency, foE), change-points are less obvious than in the mid-latitude study, presumably owing to the observation site lying under the auroral oval.

The rate of extensive showers of high electron density at sea level

1956 ◽  
Vol 3 (1) ◽  
pp. 188-194 ◽  
Author(s):  
C. B. A. McCusker ◽  
B. G. Wilson
Keyword(s):  
Sea Level ◽  
Electron Density ◽  
High Electron ◽  
High Electron Density

scholarly journals Diurnal, seasonal, annual, and semi-annual variations of ionospheric parameters at different latitudes in East Asian sector during ascending phase of solar activity

2017 ◽  
Vol 3 (2) ◽  
pp. 45-53
Author(s):  
Чжэн Ван ◽  
Zheng Wang ◽  
Цзянькуй Ши ◽  
Jiankui Shi ◽  
Гоцзюнь Ван ◽  
...  
Keyword(s):  
Solar Activity ◽  
East Asia ◽  
Seasonal Variations ◽  
Critical Frequency ◽  
East Asian ◽  
Peak Height ◽  
Scale Height ◽  
High Latitudes ◽  
Ionospheric Parameter ◽  
Annual Variations

We analyzed ionospheric parameters including the critical frequency of the F2 layer (foF2), the peak height of the F2 layer (hmF2), and the scale height at hmF2 (HT) from 2006 to 2012 (ascending phase of solar activity) at Hainan (19.5° N, 109.1° E, MLat. 9.7° N), Irkutsk (52.4° N, 104.3° E, MLat. 42.5° N), and Norilsk (69.2° N, 88.0° E, MLat. 59.8° N) stations (low, middle and high latitudes). We have used manual scaled digisonde ionogram data. Studies of foF2 and hmF2 di-urnal-seasonal variations continue those made earlier for East Asia. Features peculiar for the ascending phase of solar activity are mostly consistent to those for de-scending phase, except for the features of sunset and nighttime hmF2 variations. Features of annual and semi-annual variations recorded by a digisonde agree with those obtained by a satellite occultation and TEC map. We also obtained seasonal, diurnal, annual, and semi-annual variations of the ionospheric parameter HT (scale height at hmF2) from digisonde data, which differ from foF2 variations and hmF2 features.

scholarly journals Ionospheric climatology and variability from long-term and multiple incoherent scatter radar observations: variability

2008 ◽  
Vol 26 (6) ◽  
pp. 1525-1537 ◽  
Author(s):  
S.-R. Zhang ◽  
J. M. Holt
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Geomagnetic Activity ◽  
Plasma Temperature ◽  
High Electron ◽  
High Electron Density ◽  
Incoherent Scatter Radar ◽  
Incoherent Scatter ◽  
Scatter Radar

Abstract. Long-term incoherent scatter radar (ISR) observations are used to study ionospheric variability for two midlatitude sites, Millstone Hill and St. Santin. This work is based on our prior efforts which resulted in an empirical model system, ISR Ionospheric Model (ISRIM), of climatology (and now variability) of the ionosphere. We assume that the variability can be expressed in three terms, the background, solar activity and geomagnetic activity components, each of which is a function of local time, season and height. So the background variability is ascribed mostly to the day-to-day variability arising from non solar and geomagnetic activity sources. (1) The background variability shows clear differences between the bottomside and the topside and changes with season. The Ne variability is low in the bottomside in summer, and high in the topside in winter and spring. The plasma temperature variability increases with height, and reaches a minimum in summer. Ti variability has a marked maximum in spring; at Millstone Hill it is twice as high as at St. Santin. (2) For enhanced solar activity conditions, the overall variability in Ne is reduced in the bottomside of the ionosphere and increases in the topside. For Te, the solar activity enhancement reduces the variability in seasons of high electron density (winter and equinox) at altitudes of high electron density (near the F2-peak). For Ti, however, while the variability tends to decrease at Millstone Hill (except for altitudes near 200 km), it increases at St. Santin for altitudes up to 350 km; the solar flux influence on the variability tends to be stronger at St. Santin than at Millstone Hill.

scholarly journals Diurnal, seasonal, annual, and semi-annual variations of ionospheric parameters at different latitudes in East Asian sector during ascending phase of solar activity

2017 ◽  
Vol 3 (2) ◽  
pp. 43-50
Author(s):  
Чжэн Ван ◽  
Zheng Wang ◽  
Цзянькуй Ши ◽  
Jiankui Shi ◽  
Гоцзюнь Ван ◽  
...  
Keyword(s):  
Solar Activity ◽  
East Asia ◽  
Seasonal Variations ◽  
Critical Frequency ◽  
East Asian ◽  
Peak Height ◽  
Scale Height ◽  
High Latitudes ◽  
Ionospheric Parameter ◽  
Annual Variations

We analyzed ionospheric parameters including the critical frequency of the F2 layer (foF2), the peak height of the F2 layer (hmF2), and the scale height at hmF2 (HT) from 2006 to 2012 (ascending phase of solar activity) at Hainan (19.5° N, 109.1° E, MLat. 9.7° N), Irkutsk (52.4° N, 104.3° E, MLat. 42.5° N), and Norilsk (69.2° N, 88.0° E, MLat. 59.8° N) stations (low, middle and high latitudes). We have used manual scaled digisonde ionogram data. Studies of foF2 and hmF2 di-urnal-seasonal variations continue those made earlier for East Asia. Features peculiar for the ascending phase of solar activity are mostly consistent to those for de-scending phase, except for the features of sunset and nighttime hmF2 variations. Features of annual and semi-annual variations recorded by a digisonde agree with those obtained by a satellite occultation and TEC map. We also obtained seasonal, diurnal, annual, and semi-annual variations of the ionospheric parameter HT (scale height at hmF2) from digisonde data, which differ from foF2 variations and hmF2 features.

A new high resolution Mean Sea Surface (DTU21MSS) for improved sea level monitoring

2021 ◽  
Author(s):  
Ole Baltazar Andersen ◽  
Adil Abulaitijiang ◽  
Shengjun Zhang ◽  
Stine Kildegaard Rose
Keyword(s):  
Sea Level ◽  
Sea Surface ◽  
Ocean Tide ◽  
Simultaneous Estimation ◽  
Polar Regions ◽  
Annual Variations ◽  
Sea Level Anomalies ◽  
Ocean Tide Model ◽  
Mean Sea Surface ◽  
The Mean

<p>A new Mean Sea Surface (DTU21MSS) for referencing sea level anomalies from satellite altimetry is presented. The major new advance leading up to the release of this MSS the use of 5 years of Sentinel-3A and an improved 10 years Cryosat-2 LRM+SAR+SARin record including retracked altimetry in Polar regions using the SAMOSA+ physical retracker via the ESA GPOD facility.</p><p>A new processing chain with updated editing and data filtering has been implemented. The filtering implies, that the 20Hz sea surface height data are filtered using the Parks-McClellan filter to derive 1Hz. This has a clear advantage over the 1 Hz boxcar filter in not introducing sidelobes degrading the MSS in the 10-40 km wavelength band. Similarly, the use of consistent ocean tide model for the Mean sea surface improves the usage of sun-syncronous satellites in high latitudes.</p><p>The presentation will also focus on the difficult issues to consolidating Cryosat-2 and Sentinel-3 onto a past 20 year mean sea surface. This is implemented using simultaneous estimation of the mean, sea level trend and annual and semi-annual variations in sea level.  </p>

scholarly journals Global variation in the long-term seasonal changes observed in ionospheric F region data

2015 ◽  
Vol 33 (4) ◽  
pp. 449-455 ◽  
Author(s):  
C. J. Scott ◽  
R. Stamper
Keyword(s):  
Regional Variation ◽  
Critical Frequency ◽  
Relative Magnitude ◽  
Striking Similarity ◽  
Regional Variability ◽  
Data Set ◽  
Annual Variations ◽  
F Region ◽  
Region Data

Abstract. Long-term variability has previously been observed in the relative magnitude of annual and semi-annual variations in the critical frequency (related to the peak electron concentration) of the ionospheric F2 layer (foF2). In this paper we investigate the global patterns in such variability by calculating the time varying power ratio of semi-annual to annual components seen in ionospheric foF2 data sequences from 77 ionospheric monitoring stations around the world. The temporal variation in power ratios observed at each station was then correlated with the same parameter calculated from similar epochs for the Slough/Chilton data set (for which there exists the longest continuous sequence of ionospheric data). This technique reveals strong regional variation in the data, which bears a striking similarity to the regional variation observed in long-term changes to the height of the ionospheric F2 layer. We argue that since both the height and peak density of the ionospheric F2 region are influenced by changes to thermospheric circulation and composition, the observed long-term and regional variability can be explained by such changes. In the absence of long-term measurements of thermospheric composition, detailed modelling work is required to investigate these processes.

scholarly journals Characterization of GPS total electron content (GPS-TEC) in Antarctica from 2004 to 2011

2013 ◽  
Vol 56 (2) ◽  
Author(s):  
Emília Correia ◽  
Amanda Junqueira Paz ◽  
Mauricio A. Gende
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Annual Variations ◽  
Solar Radiation Intensity ◽  
Winter Anomaly ◽  
Semiannual Variation ◽  
The Mean

<p>The vertical total electron content (VTEC) obtained from 2004 to 2011 at Comandante Ferraz Brazilian Antarctic Station (62.1°S, 58.4°W) is analyzed to study the mean diurnal, seasonal and annual variations. The maximum daytime VTEC had an annual variation that decreased from 2004 to 2008, and then starting to increase in 2009, which followed the variation of the solar activity. The daily VTEC shows good linear correlation with solar radiation intensity, which is also dependent on the solar zenithal angle. The mean diurnal VTEC shows a semiannual variation, with larger peaks in equinoxes for all years; no winter anomaly was observed, and in summer, there was no clear diurnal variation. The semiannual variation of the VTEC is also modulated by solar activity, with larger VTEC peaks when the solar activity was higher.</p>

scholarly journals Common 22-year cycles of Earth rotation and solar activity

2009 ◽  
Vol 5 (S264) ◽  
pp. 407-409 ◽  
Author(s):  
Yavor Chapanov ◽  
Jan Vondrák ◽  
Cyril Ron
Keyword(s):  
Solar Activity ◽  
Sea Level ◽  
Earth Rotation ◽  
Geomagnetic Field ◽  
Water Evaporation ◽  
Mean Sea Level ◽  
The Core ◽  
The Earth ◽  
Geophysical Processes ◽  
The Mean

AbstractThe 22-year oscillations of the Earth rotation due to several geophysical processes in the core-mantle system, oceans, atmosphere and geomagnetic field are excited mainly by 22-year cycles of the solar activity. These geophysical processes produce their own oscillations of the Earth rotation with different periods around 22 years. The direct and indirect influence of the solar activity on 22-year cycles of the Earth rotation are separated from the core effects and corresponding amplitudes are estimated by means of two approaches. The first, direct approach uses extended time series of Wolf's numbers with 22-year cycles, determined by sign alternation of even sunspot cycles. A linear regression between 22-year cycles of UT1 and solar activity is determined and this regression model is used to calculate the UT1 response to the 22-year cycles of the solar activity. The second, indirect approach uses 22-year oscillation of the mean sea level, caused by water evaporation due to variations of the total solar irradiance. The influence of the mean sea level variations on the Earth rotation is calculated by means of an empirical model of global water redistribution. The core-mantle effects on the 22-year UT1 variations are determined by excluding the UT1 response to the solar activity and core angular momentum due to the geomagnetic field variations, according to the solutions from the Special Bureau of the Core (SBC).

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