Global sounding of sporadic E layers by the GPS/MET radio occultation experiment

Hocke, initK.K.; Igarashi, K.; Nakamura, Maho; Wilkinson, Philip; Wu, Jian; Pavelyev, A. G.; Wickert, Jens

doi:10.1016/s1364-6826(01)00063-3

Cited by 74 publications

(87 citation statements)

References 27 publications

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“…L-band scintillations and their relations with plasma irregularities at both ionospheric E-(e.g., Hocke et al, 2001;Arras et al, 2008) and F-regions (e.g., Brahmanandam et al, 2012;Dymond et al, 2012;Carter et al, 2013). Buchert et al (2015) reported that the GPS receiver onboard Swarm satellites repeatedly encountered signal interruptions during January and February 2014.…”

Section: Introductionmentioning

confidence: 99%

Climatology of GPS signal loss observed by Swarm satellites

2018

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Abstract. By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20 • magnetic latitude (MLAT) and high latitudes above 60 • MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the highlatitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20 • , and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.

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Section: Introductionmentioning

confidence: 99%

Climatology of GPS signal loss observed by Swarm satellites

2018

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“…Recently, the GNSS (global navigation satellite system)-based radio occultation (RO) technique has shown great capability in detecting the global E s occurrence by using high-resolution signal-to-noise ratio (SNR) data (Arras et al, 2008;Chu et al, 2014;Hocke et al, 2001;Wu et al, 2005;Yeh et al, 2012;Zeng and Sokolovskiy, 2010). GNSS RO technique has proven to be a powerful tool in monitoring climate, weather, and space weather (Anthes, 2011;Foelsche et al, 2011;Liu et al, 2010;Schreiner et al, 2007;Zhang et al, 2011;Yue et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…The obvious increase in slant TEC around ∼ 92 km implies the ionization enhancement in the E s layer. Based on all available GPS/MET RO data, Hocke et al (2001) did a statistical analysis on the global E s occurrence and compared the results with the ionosonde observations. Wu et al (2005) did a more robust statistical analysis on the global E s using CHAMP RO data.…”

Section: Introductionmentioning

confidence: 99%

Case study on complex sporadic E layers observed by GPS radio occultations

et al. 2015

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Abstract. The occurrence of sporadic E (E s ) layers has been a hot scientific topic for a long time. The GNSS (global navigation satellite system)-based radio occultation (RO) has proven to be a powerful technique for detecting the global E s layers. In this paper, we focus on some cases of complex E s layers based on the RO data from multiple missions processed in UCAR/CDAAC (University Corporation for Atmospheric Research (UCAR) the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Data Analysis and Archive Center (CDAAC)). We first show some examples of multiple E s layers occurred in one RO event. Based on the evaluations between colocated simultaneous RO events and between RO and lidar observations, it could be concluded that some of these do manifest the multiple E s layer structures. We then show a case of the occurrence of E s in a broad region during a certain time interval. The result is then validated by independent ionosondes observations. It is possible to explain these complex E s structures using the popular wind shear theory. We could map the global E s occurrence routinely in the near future, given that more RO data will be available. Further statistical studies will enhance our understanding of the E s mechanism. The understanding of E s should benefit both E s -based long-distance communication and accurate neutral RO retrievals.

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“…Considering that using pseudoranges provide absolute TEC while using phase differences improves the accuracy, GNSS data provides for the efficient method of estimating TEC values with greater spatial and temporal coverage (Davies and Hartmann, 1997;Igarashi et al, 2001). Having that the frequencies used by the GNSS system are sufficiently high, the signals are minimally influenced by ionospheric absorption and Earth's magnetic field, both in the short and in the long-term changes in the ionosphere structure.…”

Section: Tec Based On Gnss Observationmentioning

confidence: 99%

Modelling extreme values of the total electron content: Case study of Serbia

et al. 2017

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This paper is dedicated to modeling extreme TEC (Total Electron Content) values at the territory of Serbia. For the extreme TEC values, we consider the maximum values from the peak of the 11-year cycle of solar activity in the years 2013, 2014 and 2015 for the days of the winter and summer solstice and autumnal and vernal equinox. The average TEC values between 10 and 12 UT (Universal Time) were treated. As the basic data for all processing, we used GNSS (Global Navigation Satellite System) observation obtained by three permanent stations located in the territory of Serbia. Those data, we accept as actual, i.e. as a "true TEC values". The main objectives of this research were to examine the possibility to use two machine learning techniques: neural networks and support vector machine. In order to emphasize the quality of applied techniques, all results are adequately compared to the TEC values obtained by using International Reference Ionosphere global model. In addition, we separately analyzed the quality of techniques throughout temporal and spatial-temporal approach.

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Global sounding of sporadic E layers by the GPS/MET radio occultation experiment

Cited by 74 publications

References 27 publications

Climatology of GPS signal loss observed by Swarm satellites

Climatology of GPS signal loss observed by Swarm satellites

Case study on complex sporadic E layers observed by GPS radio occultations

Modelling extreme values of the total electron content: Case study of Serbia

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