Derivation and test of ionospheric activity indices from real-time ionosonde observations in the European region

Bremer, J.; Cander, Ljiljana R.; Mielich, Jens; Stamper, R.

doi:10.1016/j.jastp.2006.07.003

Cited by 24 publications

(33 citation statements)

References 16 publications

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“…The advantage is that such values contain information about ionospheric height changes. However, as shown in Bremer et al (2006) these activity indices are less sensitive to ionospheric variability. Therefore, we concentrate in this paper only on investigations of AI values derived from foF2 observations according to Eq.…”

Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 92%

“…In Bremer et al (2006) the reference value was the median value of the last 30 (or 27) days before the current foF2 value at the same local time. In this paper we use a slightly modified procedure, calculating the reference value by a simple linear regression analysis with the data of the last 27 days before the current foF2 value and calculate foF2 ref from this regression equation for the same hour as the current value foF2.…”

Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 99%

“…The choice of a 27 days interval is physically more plausible due to the solar rotation period. In practice, however, it is not essential if the interval is 27 or 30 days as demonstrated in Bremer et al (2006). In principle it is also possible to derive AI values also from M(3000)F2 observations.…”

Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 99%

“…Such ionospheric activity indices are important for users to know if the current ionospheric state is that to be expected from mean solar activity level or is modified by short term solar, geomagnetic or atmospheric disturbances (solar flares, geomagnetic events, atmospheric waves etc.). Details of this procedure and first results have been reported by Bremer et al (2006).…”

Section: Introductionmentioning

confidence: 99%

“…Whereas Bremer et al (2006) investigated data of a short time interval (October 2003until March 2005 at different European ionosonde stations here long-lasting data during the solar activity cycle 23 (January 1996until December 2008 are used from observations at the ionosonde station Juliusruh (54.6 • N; 13.4 • E). Besides hourly AI values have been derived based only on hourly foF2 observations as these indices are more sensitive to ionospheric variability than the indices derived from M(3000)F2 values.…”

Section: Introductionmentioning

confidence: 99%

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A modified index for the description of the ionospheric short- and long-term activity

Mielich

Bremer

2010

Ann. Geophys.

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Abstract.A modified ionospheric activity index AI has been developed on the basis of ionospheric foF2 observations. Such index can be helpful for an interested user to get information about the current state of the ionosphere. Using ionosonde data of the station Juliusruh (54.6 • N; 13.4 • E) this index has been tested for the time interval from January 1996 until December 2008. This index has no diurnal and seasonal variations, only a small positive dependence on the solar activity could be found. The variability of this index has, however, a marked seasonal variability with maxima during the equinoxes, a clear minimum in summer, and enhanced values in winter. The observed variability of AI is strongly correlated with the geomagnetic activity, most markedly during the equinoxes, whereas the influence of the solar activity is markedly smaller and mostly insignificant. Strong geomagnetic disturbances cause in middle latitudes in general negative disturbances in AI, mostly pronounced during equinoxes and summer and only partly during winter, thus in agreement with the current physical knowledge about ionospheric storms.

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Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 92%

Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 99%

Section: Description Of the Experimental Data And Methodical Investigmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A modified index for the description of the ionospheric short- and long-term activity

Mielich

Bremer

2010

Ann. Geophys.

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A new ionospheric storm scale based on TEC and f_oF₂ statistics

et al. 2017

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In this paper, we propose the I‐scale, a new ionospheric storm scale for general users in various regions in the world. With the I‐scale, ionospheric storms can be classified at any season, local time, and location. Since the ionospheric condition largely depends on many factors such as solar irradiance, energy input from the magnetosphere, and lower atmospheric activity, it had been difficult to scale ionospheric storms, which are mainly caused by solar and geomagnetic activities. In this study, statistical analysis was carried out for total electron content (TEC) and F2 layer critical frequency (foF2) in Japan for 18 years from 1997 to 2014. Seasonal, local time, and latitudinal dependences of TEC and foF2 variabilities are excluded by normalizing each percentage variation using their statistical standard deviations. The I‐scale is defined by setting thresholds to the normalized numbers to seven categories: I0, IP1, IP2, IP3, IN1, IN2, and IN3. I0 represents a quiet state, and IP1 (IN1), IP2 (IN2), and IP3 (IN3) represent moderate, strong, and severe positive (negative) storms, respectively. The proposed I‐scale can be used for other locations, such as polar and equatorial regions. It is considered that the proposed I‐scale can be a standardized scale to help the users to assess the impact of space weather on their systems.

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Brazilian active GNSS networks as systems for monitoring the ionosphere

Pereira

Camargo

2016

GPS Solut

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This research shows the viability of using Global Navigation Satellite System (GNSS) stations from Brazilian active networks in monitoring the ionosphere. Various indexes of ionospheric irregularities and scintillation of GNSS signals, estimated in real-time and post-processed from GNSS data, are explored for this purpose. This way, an increase in the spatial resolution of ionospheric information is provided, allowing the generation of maps of scintillation and irregularities in observing the spatial and temporal behavior of the layer's activity cycle, since the number of ionosondes, imagers, and radars is insufficient for monitoring the irregularities in Brazil. Experiments to evaluate the estimates of the indexes are performed for periods of high and low variability of electrons. Three Brazilian networks are used: the Brazilian Network for Continuous Monitoring (RBMC), the GNSS Active Network of Sao Paulo State (GNSS-SP), and CIGALA/ CALIBRA. The results are compared with data from ionosondes and PolaRxS-PRO Septentrio receivers, proving compatible with moderate to high correlations. An analysis of the seasonal variation during the peak of solar cycle 24 is carried out. The maps allow identifying the displacement of ionospheric irregularities along the magnetic equator over Brazil, from northeast to southwest, starting at 7:00 pm and ending at 2:00 am local time. Realtime monitoring is carried out for the summer solstice in the southern hemisphere, and results are consistent with those from the post-processed mode. The indexes and maps can be applied to the analysis of GNSS positioning. Realtime ionospheric information can be used in important practical applications because the displacement monitoring of irregularities allows prior knowledge of whether there will be a deterioration of positioning accuracy in a certain region.

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Derivation and test of ionospheric activity indices from real-time ionosonde observations in the European region

Cited by 24 publications

References 16 publications

A modified index for the description of the ionospheric short- and long-term activity

A modified index for the description of the ionospheric short- and long-term activity

A new ionospheric storm scale based on TEC and f_oF₂ statistics

Brazilian active GNSS networks as systems for monitoring the ionosphere

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Derivation and test of ionospheric activity indices from real-time ionosonde observations in the European region

Cited by 24 publications

References 16 publications

A modified index for the description of the ionospheric short- and long-term activity

A modified index for the description of the ionospheric short- and long-term activity

A new ionospheric storm scale based on TEC and foF2 statistics

Brazilian active GNSS networks as systems for monitoring the ionosphere

Contact Info

Product

Resources

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A new ionospheric storm scale based on TEC and f_oF₂ statistics