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Long-term prediction of the Arctic ionospheric TEC based on time-varying periodograms.

Liu J, Chen R, Wang Z, An J, Hyyppä J - PLoS ONE (2014)

Bottom Line: The TEC time series is divided into two components of periodic oscillations and the average TEC.The backward prediction indicates that the Arctic TEC variability includes a 9 years period for the study duration, in addition to the well-established periods.The long-term prediction has an uncertainty of 4.8-5.6 TECU for different period sets.

View Article: PubMed Central - PubMed

Affiliation: Department of remote sensing and photogrammetry, Finnish Geodetic Institute, Masala, Finland.

ABSTRACT
Knowledge of the polar ionospheric total electron content (TEC) and its future variations is of scientific and engineering relevance. In this study, a new method is developed to predict Arctic mean TEC on the scale of a solar cycle using previous data covering 14 years. The Arctic TEC is derived from global positioning system measurements using the spherical cap harmonic analysis mapping method. The study indicates that the variability of the Arctic TEC results in highly time-varying periodograms, which are utilized for prediction in the proposed method. The TEC time series is divided into two components of periodic oscillations and the average TEC. The newly developed method of TEC prediction is based on an extrapolation method that requires no input of physical observations of the time interval of prediction, and it is performed in both temporally backward and forward directions by summing the extrapolation of the two components. The backward prediction indicates that the Arctic TEC variability includes a 9 years period for the study duration, in addition to the well-established periods. The long-term prediction has an uncertainty of 4.8-5.6 TECU for different period sets.

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The geographical locations of the IGS tracking stations in the Arctic area.Land is indicated by brown, and sea/ocean is represented by blue. The yellow points indicate the locations of the IGS stations used in this study.
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pone-0111497-g001: The geographical locations of the IGS tracking stations in the Arctic area.Land is indicated by brown, and sea/ocean is represented by blue. The yellow points indicate the locations of the IGS stations used in this study.

Mentions: In the present study, the geographical North Pole is the spherical cap pole of the interested area, and the half angle is 30 degrees (), the maximum degree is 8 and the maximum order is 6 . The number of model parameters is 75 in total. The Arctic ionospheric TEC is estimated using GPS measurements from 44 IGS tracking stations located at high latitudes (above 55° North latitude, as shown in Figure 1) and related IGS products, including IGS precise orbit data, and differential code bias (DCB) products of receivers and satellites provided by the Center for Orbit Determination in Europe (CODE) (ftp://ftp.unibe.ch/aiub/CODE). Table I listed the used IGS stations with their geographical coordinates. One should note that some IGS stations located in the Arctic were not included in Table I because their DCB products of receivers are missing from the database. Some pairs of stations have very close coordinates because the two receivers share the observation facility. The measurement dataset of the study period from 2000 to 2013 is provided in RINEX (Receiver Independent Exchange) format by the IGS central bureau via ftp access (ftp://cddis.gsfc.nasa.gov/gps/data/daily/). Before the study period, GPS tracking stations in the Arctic region are not sufficient to map ionospheric TEC. The sample rate of the GPS measurements is 30 seconds, and the elevation cut-off threshold is 20 degrees in the data processing. The sp3 satellite orbit products are used to calculate the precise positions of satellites and further calculate the positions of the ionosphere pierce points and elevations of GPS signal paths. The Spline interpolation method is used to interpolate the satellite positions at the observation epochs. Based on the estimated Arctic TEC, the analysis and prediction are presented as follows. The reference index data such as solar and geomagnetic indices have been downloaded from the national geophysical data center (ftp://ftp.ngdc.noaa.gov/STP/).


Long-term prediction of the Arctic ionospheric TEC based on time-varying periodograms.

Liu J, Chen R, Wang Z, An J, Hyyppä J - PLoS ONE (2014)

The geographical locations of the IGS tracking stations in the Arctic area.Land is indicated by brown, and sea/ocean is represented by blue. The yellow points indicate the locations of the IGS stations used in this study.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4219753&req=5

pone-0111497-g001: The geographical locations of the IGS tracking stations in the Arctic area.Land is indicated by brown, and sea/ocean is represented by blue. The yellow points indicate the locations of the IGS stations used in this study.
Mentions: In the present study, the geographical North Pole is the spherical cap pole of the interested area, and the half angle is 30 degrees (), the maximum degree is 8 and the maximum order is 6 . The number of model parameters is 75 in total. The Arctic ionospheric TEC is estimated using GPS measurements from 44 IGS tracking stations located at high latitudes (above 55° North latitude, as shown in Figure 1) and related IGS products, including IGS precise orbit data, and differential code bias (DCB) products of receivers and satellites provided by the Center for Orbit Determination in Europe (CODE) (ftp://ftp.unibe.ch/aiub/CODE). Table I listed the used IGS stations with their geographical coordinates. One should note that some IGS stations located in the Arctic were not included in Table I because their DCB products of receivers are missing from the database. Some pairs of stations have very close coordinates because the two receivers share the observation facility. The measurement dataset of the study period from 2000 to 2013 is provided in RINEX (Receiver Independent Exchange) format by the IGS central bureau via ftp access (ftp://cddis.gsfc.nasa.gov/gps/data/daily/). Before the study period, GPS tracking stations in the Arctic region are not sufficient to map ionospheric TEC. The sample rate of the GPS measurements is 30 seconds, and the elevation cut-off threshold is 20 degrees in the data processing. The sp3 satellite orbit products are used to calculate the precise positions of satellites and further calculate the positions of the ionosphere pierce points and elevations of GPS signal paths. The Spline interpolation method is used to interpolate the satellite positions at the observation epochs. Based on the estimated Arctic TEC, the analysis and prediction are presented as follows. The reference index data such as solar and geomagnetic indices have been downloaded from the national geophysical data center (ftp://ftp.ngdc.noaa.gov/STP/).

Bottom Line: The TEC time series is divided into two components of periodic oscillations and the average TEC.The backward prediction indicates that the Arctic TEC variability includes a 9 years period for the study duration, in addition to the well-established periods.The long-term prediction has an uncertainty of 4.8-5.6 TECU for different period sets.

View Article: PubMed Central - PubMed

Affiliation: Department of remote sensing and photogrammetry, Finnish Geodetic Institute, Masala, Finland.

ABSTRACT
Knowledge of the polar ionospheric total electron content (TEC) and its future variations is of scientific and engineering relevance. In this study, a new method is developed to predict Arctic mean TEC on the scale of a solar cycle using previous data covering 14 years. The Arctic TEC is derived from global positioning system measurements using the spherical cap harmonic analysis mapping method. The study indicates that the variability of the Arctic TEC results in highly time-varying periodograms, which are utilized for prediction in the proposed method. The TEC time series is divided into two components of periodic oscillations and the average TEC. The newly developed method of TEC prediction is based on an extrapolation method that requires no input of physical observations of the time interval of prediction, and it is performed in both temporally backward and forward directions by summing the extrapolation of the two components. The backward prediction indicates that the Arctic TEC variability includes a 9 years period for the study duration, in addition to the well-established periods. The long-term prediction has an uncertainty of 4.8-5.6 TECU for different period sets.

Show MeSH