Error analysis of Abel retrieved electron density profiles from radio occultation measurements

Yue, Xinan; Schreiner, William S.; Lei, Jiuhou; Sokolovskiy, Sergey; Rocken, Christian; Hunt, Douglas; Kuo, Ying Hwa

doi:10.5194/angeo-28-217-2010

Cited by 206 publications

(276 citation statements)

References 18 publications

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“…The COSMIC data have been broadly used for studying the ionospheric phenomena. Although the retrieval errors tend to increase closer to low latitudes and low altitudes [Yue et al, 2010], COSMIC electron density profiles in middle latitudes have shown a good agreement with ground observations [Lei et al, 2007]. The N m F 2 and h m F 2 derived from COSMIC profiles have also shown a good agreement with those derived from ionosonde measurements [Krankowski et al, 2011].…”

supporting

confidence: 68%

Reply to comment by A. V. Mikhailov and L. Perrone on “The winter anomaly in the middle‐latitude F region during the solar minimum period observed by the Constellation Observing System for Meteorology, Ionosphere, and Climate”

et al. 2014

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Lee et al. [2011] (hereafter L11) investigated the winter anomaly on a global scale using the electron density profiles acquired during the previous solar minimum by the Global Positioning System (GPS) radio occultation experiment payload on board the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. The comment mentioned that L11 did not credit former studies for the investigation of the altitudinal variation of the winter anomaly. Missing citation of those studies was our mistake. However, we claimed nowhere that our report is the first investigation of the altitudinal variation of the phenomenon. One of the references that the comment provided [Boenkova and Mednikova, 1972] was written with Russian and not available.The comment mentioned that L11 did not provide references for the description of the nighttime increase of the h m F 2 and N m F 2 . The increase of the h m F 2 and N m F 2 at night by the effect of neutral wind is already well known, as the comment stated, so references were not provided.The comment claimed that L11 repeatedly mentioned the effect of "vibrationally excited N 2 and O 2 number density." It was mentioned twice (paragraphs [5] and [21]) to introduce previous studies that explained the winter anomaly in association with the vibrationally excited N 2 and O 2 number density. L11 clearly stated that this effect varies with the solar activity. So we disagree with the claim: "There is no need to mention vibrationally excited N 2 for the interpretation of the seasonal anomaly under solar minimum conditions."The comment mentioned that the formation of the F 2 layer is nothing to do with the solar EUV radiation, so our description of the dependence of the electron density on the solar zenith angle is incorrect. We do not agree with this comment. The dependence of the ionization on the solar zenith angle is obvious from the Chapman function, as presented in many textbooks (see Figure

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supporting

confidence: 68%

Reply to comment by A. V. Mikhailov and L. Perrone on “The winter anomaly in the middle‐latitude F region during the solar minimum period observed by the Constellation Observing System for Meteorology, Ionosphere, and Climate”

et al. 2014

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“…However, an extensive pre-processing and data screening was necessary for both the RO and ionosonde data to eliminate disturbances in the data and improve the data reliability. Many authors like Krankowski et al (2011), Hu et al (2014, Wu et al (2009), Yue et al (2010, and Lei et al (2007) evaluated the accuracy of electron density peaks, retrieved from F-3/C data, either on a regional scale by means of selected ionosonde stations allowing for a manual ionogram scaling or even used synthetic data to validate the accuracy under different conditions, e.g., under the influence of varying F10.7 indices. In this work, SPIDR network data based on automatically scaled measurements are taken into account.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, Wu et al (2009) Lei et al (2007) evaluated correlations of maximum electron densities between F-3/C EDPs and ionosondes at the early stage of the constellation in July 2006. Krankowski et al (2011) validated F2 peak parameters of F-3/C measurements in the European sector during 2008 andYue et al (2010) studied the retrieval accuracy by means of synthetic data driven by background information of the NeQuick model to determine absolute and relative accuracies for NmF2 and hmF2.…”

Section: Introductionmentioning

confidence: 99%

Long-term comparison of the ionospheric F2 layer electron density peak derived from ionosonde data and Formosat-3/COSMIC occultations

Limberger¹,

Hernández‐Pajares

Aragón‐Àngel

et al. 2015

J. Space Weather Space Clim.

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Electron density profiles (EDPs) derived from GNSS radio occultation (RO) measurements provide valuable information on the vertical electron density structure of the ionosphere and, among others, allow the extraction of key parameters such as the maximum electron density NmF2 and the corresponding peak height hmF2 of the F2 layer. An efficient electron density retrieval method, developed at the UPC (Barcelona, Spain), has been applied in this work to assess the accuracy of NmF2and hmF2 as determined from Formosat-3/COSMIC (F-3/C) radio occultation measurements for a period of more than half a solar cycle be- ) and local times (LT) accounting for different ionospheric conditions at night (02:00 LT ± 2 h), dawn (08:00 LT ± 2 h), and day (14:00 LT ± 2 h). The mean differences of F2 layer electron density peaks observed by F-3/C and ionosondes are found to be insignificant. Relative variations of the peak differences are determined in the range of 22%-30% for NmF2 and 10%-15% for hmF2. The consistency of observations is generally high for the equatorial and mid-latitude sectors at daytime and dawn whereas degradations have been detected in the polar regions and during night. It is shown, that the global averages of NmF2 and hmF2 derived from F-3/C occultations appear as excellent indicators for the solar activity.

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“…Our results are consistent with previous validation results comparing RO retrievals to ionosonde measurements. Comparison of COSMIC Ne profiles with NeQuick-derived profiles revealed good correlation; the standard deviation was ∼15% for NmF2 and ∼2% for hmF2 corresponded to global scale analysis (Yue et al 2010). There are several studies examining and estimating the accuracy of the retrieved COS-MIC Ne profiles by comparing them with globally distributed ionosonde data obtained from the National Geophysical Data Center (NGDC-NOAA) SPIDR (The Space Physics Interactive Data Resource) database (http://spidr.ngdc.noaa.gov/ spidr/).…”

Section: Comparison With European Ionosondes Data (Case-study)mentioning

confidence: 99%

“…The main source of inversion error is the spherical symmetry approximation. Yue et al (2010) compared COS-MIC Ne profiles with those obtained from the NeQuick empirical ionosphere electron density model. These simulations demonstrated that the Abel inversion method introduces significant errors in electron densities in the low-latitude region.…”

Section: Cosmic Datamentioning

confidence: 99%

Ionospheric electron density observed by FORMOSAT-3/COSMIC over the European region and validated by ionosonde data

Krankowski

Zakharenkova

Krypiak-Gregorczyk

et al. 2011

J Geod

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This research is motivated by the recent IGS Ionosphere Working Group recommendation issued at the IGS 2010 Workshop held in Newcastle, UK. This recommendation encourages studies on the evaluation of the application of COSMIC radio occultation profiles for additional IGS global ionosphere map (GIM) validation. This is because the reliability of GIMs is crucial to many geodetic applications. On the other hand, radio occultation using GPS signals has been proven to be a promising technique to retrieve accurate profiles of the ionospheric electron density with high vertical resolution on a global scale. However, systematic validation work is still needed before using this powerful technique for sounding the ionosphere on a routine basis. In this paper, we analyze the properties of the ionospheric electron density profiling retrieved from COSMIC radio occultation measurements. A comparison of radio occultation data with groundbased measurements indicates that COSMIC profiles are usually in good agreement with ionosonde profiles, both in the F2 layer peak electron density and the bottom side of the profiles. For this comparison, ionograms recorded by European ionospheric stations (DIAS network) in 2008 were used.

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Error analysis of Abel retrieved electron density profiles from radio occultation measurements

Cited by 206 publications

References 18 publications

Reply to comment by A. V. Mikhailov and L. Perrone on “The winter anomaly in the middle‐latitude F region during the solar minimum period observed by the Constellation Observing System for Meteorology, Ionosphere, and Climate”

Reply to comment by A. V. Mikhailov and L. Perrone on “The winter anomaly in the middle‐latitude F region during the solar minimum period observed by the Constellation Observing System for Meteorology, Ionosphere, and Climate”

Long-term comparison of the ionospheric F2 layer electron density peak derived from ionosonde data and Formosat-3/COSMIC occultations

Ionospheric electron density observed by FORMOSAT-3/COSMIC over the European region and validated by ionosonde data

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