Sporadic structures and small-scale irregularity in the nighttime polar ionosphere in the period of high solar activity according to the data of radio occultation measurements on satellite-to-satellite paths

2009 ◽  
Vol 47 (4) ◽  
pp. 259-267 ◽  
Author(s):  
O. I. Yakovlev ◽  
S. S. Matyugov ◽  
V. A. Anufriev ◽  
G. P. Cherkunova
Keyword(s):  
Solar Activity ◽  
Radio Occultation ◽  
High Solar Activity ◽  
Small Scale ◽  
Polar Ionosphere ◽  
Small Scale Irregularity

scholarly journals Occurrence climatology of equatorial plasma bubbles derived using FormoSat-3 ∕ COSMIC GPS radio occultation data

2020 ◽  
Vol 38 (3) ◽  
pp. 611-623
Author(s):  
Ankur Kepkar ◽  
Christina Arras ◽  
Jens Wickert ◽  
Harald Schuh ◽  
Mahdi Alizadeh ◽  
...  
Keyword(s):  
Solar Activity ◽  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Strong Dependence ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Altitudinal Distribution ◽  
Plasma Bubbles ◽  
Ionosphere Plasma ◽  
Equatorial Plasma Bubbles

Abstract. The Global Positioning System – Radio Occultation (GPS-RO) observations from FormoSat-3 ∕ COSMIC are used to comprehend the global distribution of equatorial plasma bubbles which are characterized by depletion regions of plasma in the F region of the ionosphere. Plasma bubbles that cause intense scintillation of the radio signals are identified based on the S4 index derived from the 1 Hz raw signal-to-noise ratio measurements between 2007 and 2017. The analyses revealed that bubbles influenced by background plasma density occurred along the geomagnetic equator and had an occurrence peak around the dip equator during high solar activity. The peak shifted between the African and American sectors, depending on different solar conditions. Plasma bubbles usually developed around 19:00 local time (LT), with maximum occurrence around 21:00 LT during solar maximum and ∼22:00 LT during solar minimum. The occurrence of bubbles showed a strong dependence on longitudes, seasons, and solar cycle with the peak occurrence rate in the African sector around the March equinox during high solar activity, which is consistent with previous studies. The GPS-RO technique allows an extended analysis of the altitudinal distribution of global equatorial plasma bubbles obtained from high vertical resolution profiles, thus making it a convenient tool which could be further used with other techniques to provide a comprehensive view of such ionospheric irregularities.

scholarly journals Systematic residual ionospheric errors in radio occultation data and a potential way to minimize them

2013 ◽  
Vol 6 (8) ◽  
pp. 2169-2179 ◽  
Author(s):  
J. Danzer ◽  
B. Scherllin-Pirscher ◽  
U. Foelsche
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Radio Occultation ◽  
Simulated Data ◽  
Correction Method ◽  
High Solar Activity ◽  
Neutral Atmosphere ◽  
Atmospheric Parameters ◽  
Ionospheric Correction ◽  
Bending Angle

Abstract. Radio occultation (RO) sensing is used to probe the earth's atmosphere in order to obtain information about its physical properties. With a main interest in the parameters of the neutral atmosphere, there is the need to perform a correction of the ionospheric contribution to the bending angle. Since this correction is an approximation to first order, there exists an ionospheric residual, which can be expected to be larger when the ionization is high (day versus night, high versus low solar activity). The ionospheric residual systematically affects the accuracy of the atmospheric parameters at low altitudes, at high altitudes (above 25–30 km) it even is an important error source. In climate applications this could lead to a time dependent bias which induces wrong trends in atmospheric parameters at high altitudes. The first goal of our work was to study and characterize this systematic residual error. In a second step we developed a simple correction method, based purely on observational data, to reduce this residual for large ensembles of RO profiles. In order to tackle this problem, we analyzed the bending angle bias of CHAMP and COSMIC RO data from 2001–2011. We could observe that the nighttime bending angle bias stays constant over the whole period of 11 yr, while the daytime bias increases from low to high solar activity. As a result, the difference between nighttime and daytime bias increases from about −0.05 μrad to −0.4 μrad. This behavior paves the way to correct the solar cycle dependent bias of daytime RO profiles. In order to test the newly developed correction method we performed a simulation study, which allowed to separate the influence of the ionosphere and the neutral atmosphere. Also in the simulated data we observed a similar increase in the bias in times from low to high solar activity. In this simulation we performed the climatological ionospheric correction of the bending angle data, by using the bending angle bias characteristics of a solar cycle as a correction factor. After the climatological ionospheric correction the bias of the simulated data improved significantly, not only in the bending angle but also in the retrieved temperature profiles.

scholarly journals A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation

2019 ◽  
Vol 11 (11) ◽  
pp. 1386
Author(s):  
Zhendi Liu ◽  
Hanxian Fang ◽  
M. M. Hoque ◽  
Libin Weng ◽  
Shenggao Yang ◽  
...  
Keyword(s):  
Solar Activity ◽  
Radio Occultation ◽  
Geomagnetic Latitude ◽  
Correlation Coefficients ◽  
Density Model ◽  
High Solar Activity ◽  
Cosmic Radio ◽  
Peak Density ◽  
Using Data ◽  
Better Than

To facilitate F2-layer peak density (NmF2) modeling, a nonlinear polynomial model approach based on global NmF2 observational data from ionospheric radio occultation (IRO) measurements onboard the CHAMP, GRACE, and COSMIC satellites, is presented in this paper. We divided the globe into 63 slices from 80°S to 80°N according to geomagnetic latitude. A Nonlinear Polynomial Peak Density Model (NPPDM) was constructed by a multivariable least squares fitting to NmF2 measurements in each latitude slice and the dependencies of NmF2 on solar activity, geographical longitude, universal time, and day of year were described. The model was designed for quiet and moderate geomagnetic conditions (Ap ≤ 32). Using independent radio occultation data, quantitative analysis was made. The correlation coefficients between NPPDM predictions and IRO data were 0.91 in 2002 and 0.82 in 2005. The results show that NPPDM performs better than IRI2016 and Neustrelitz Peak Density Model (NPDM) under low solar activity, while it undergoes performance degradation under high solar activity. Using data from twelve ionosonde stations, the accuracy of NPPDM was found to be better than that of NPDM and comparable to that of IRI2016. Additionally, NPPDM can well simulate the variations and distributions of NmF2 and describe some ionospheric features, including the equatorial ionization anomaly, the mid-latitude trough, and the wavenumber-four longitudinal structure.

Radiowave fluctuations in the polar ionosphere on the satellite-to-satellite paths under high solar activity

2006 ◽  
Vol 49 (3) ◽  
pp. 167-173 ◽  
Author(s):  
O. I. Yakovlev ◽  
J. Wickert ◽  
S. S. Matyugov ◽  
V. A. Anufriev
Keyword(s):  
Solar Activity ◽  
High Solar Activity ◽  
Polar Ionosphere

Results of radio occultation measurement of polar ionosphere at satellite-to-satellite paths during strong flare solar activity

2010 ◽  
Vol 67 (3-4) ◽  
pp. 315-323 ◽  
Author(s):  
O.I. Yakovlev ◽  
J. Wickert ◽  
A.G. Pavelyev ◽  
G.P. Cherkunova ◽  
V.A. Anufriev
Keyword(s):  
Solar Activity ◽  
Radio Occultation ◽  
Polar Ionosphere ◽  
Radio Occultation Measurement

scholarly journals Systematic residual ionospheric errors in radio occultation data and a potential way to minimize them

2013 ◽  
Vol 6 (1) ◽  
pp. 1979-2008 ◽  
Author(s):  
J. Danzer ◽  
B. Scherllin-Pirscher ◽  
U. Foelsche
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Radio Occultation ◽  
Simulated Data ◽  
Correction Method ◽  
High Solar Activity ◽  
Neutral Atmosphere ◽  
Atmospheric Parameters ◽  
Ionospheric Correction ◽  
Bending Angle

Abstract. Radio Occultation (RO) sensing is used to probe the Earth's atmosphere in order to obtain information about its physical properties. With a main interest in the parameters of the neutral atmosphere, there is the need to perform a correction of the ionospheric contribution to the bending angle. Since this correction is an approximation to first order, there exists an ionospheric residual, which can be expected to be larger when the ionization is high (day versus night, high versus low solar activity). The ionospheric residual systematically affects the accuracy of the atmospheric parameters at low altitudes, at high altitudes (above 25 km to 30 km) it even is an important error source. In climate applications this could lead to a time dependent bias which induces wrong trends in atmospheric parameters at high altitudes. The first goal of our work was to study and characterize this systematic residual error. In a second step we developed a simple correction method, based purely on observational data, to reduce this residual for large ensembles of RO profiles. In order to tackle this problem we analyzed the bending angle bias of CHAMP and COSMIC RO data from 2001 to 2011. We could observe that the night time bending angle bias stays constant over the whole period of 11 yr, while the day time bias increases from low to high solar activity. As a result, the difference between night and day time bias increases from about −0.05 μrad to −0.4 μrad. This behavior paves the way to correct the solar cycle dependent bias of day time RO profiles. In order to test the newly developed correction method we performed a simulation study, which allowed to separate the influence of the ionosphere and the neutral atmosphere. Also in the simulated data we observed a similar increase in the bias in times from low to high solar activity. In this model world we performed the climatological ionospheric correction of the bending angle data, by using the bending angle bias characteristics of a solar cycle as a correction factor. After the climatological ionospheric correction the bias of the simulated data improved significantly, not only in the bending angle but also in the retrieved temperature profiles.

Performance of the ionospheric kappa-correction of radio occultation profiles under diverse ionization and solar activity conditions

2021 ◽  
Author(s):  
Julia Danzer ◽  
Stephanie Juliane Haas ◽  
Marc Schwaerz ◽  
Gottfried Kirchengast
Keyword(s):  
Solar Activity ◽  
Radio Occultation

scholarly journals Numerical Simulation of the Time Evolution of Small-Scale Irregularities in the F-Layer Ionospheric Plasma

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
O. V. Mingalev ◽  
G. I. Mingaleva ◽  
M. N. Melnik ◽  
V. S. Mingalev
Keyword(s):  
Magnetic Field ◽  
Time Evolution ◽  
Ionospheric Plasma ◽  
Debye Length ◽  
Small Scale ◽  
System Of Equations ◽  
Applied Model ◽  
Positive Ions ◽  
F Region ◽  
Small Scale Irregularity

Dynamics of magnetic field-aligned small-scale irregularities in the electron concentration, existing in the F-layer ionospheric plasma, is investigated with the help of a mathematical model. The plasma is assumed to be a rarefied compound consisting of electrons and positive ions and being in a strong, external magnetic field. In the applied model, kinetic processes in the plasma are simulated by using the Vlasov-Poisson system of equations. The system of equations is numerically solved applying a macroparticle method. The time evolution of a plasma irregularity, having initial cross-section dimension commensurable with a Debye length, is simulated during the period sufficient for the irregularity to decay completely. The results of simulation indicate that the small-scale irregularity, created initially in the F-region ionosphere, decays accomplishing periodic damped vibrations, with the process being collisionless.

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