Plasmasphere effects for GPS TEC measurements in North America

Mazzella, Andrew J.

doi:10.1029/2009rs004186

Cited by 23 publications

(43 citation statements)

References 17 publications

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“…Ciraolo and Spalla 1997) with further discussion of the effects of the layer above 1,000 km in e.g. (Mazzella 2009). For more detailed information on the ionosphere, see e.g.…”

Section: Characteristics and Variabilitymentioning

confidence: 98%

A Review of Higher Order Ionospheric Refraction Effects on Dual Frequency GPS

et al. 2010

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Higher order ionospheric effects are increasingly relevant as precision requirements on GPS data and products increase. The refractive index of the ionosphere is affected by its electron content and the magnetic field of the Earth, so the carrier phase of the GPS L1 and L2 signals is advanced and the modulated code delayed. Due to system design the polarisation is unaffected. Most of the effect is removed by expanding the refractive index as a series and eliminating the first term with a linear combination of the two signals. However, the higher order terms remain. Furthermore, transiting gradients in refractive index at a non-perpendicular angle causes signal bending. In addition to the initial geometric bending term, another term allows for the difference that the curvature makes in electron content along each signal. Varying approximations have been made for practical implementation, mainly to avoid the need for a vertical profile of electron density. The magnetic field may be modelled as a tilted co-centric dipole, or using more realistic models such as the International Geomagnetic Reference Field. The largest effect is from the second term in the expansion of the refractive index. Up to several cm on L2, it particularly affects z-translation, and satellite orbits and clocks in a global network of GPS stations. The third term is at the level of the errors in modelling the second order term, while the bending terms appear to be absorbed by tropospheric parameters. Modelling improvements are possible, and three frequency transmissions will allow new possibilities.

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“…Ciraolo and Spalla 1997) with further discussion of the effects of the layer above 1,000 km in e.g. (Mazzella 2009). For more detailed information on the ionosphere, see e.g.…”

Section: Characteristics and Variabilitymentioning

confidence: 98%

A Review of Higher Order Ionospheric Refraction Effects on Dual Frequency GPS

et al. 2010

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“…One might be able to adjust for this error by increasing the projection shell height; however, as shown in Table 2 with the true CM height, the high degree of asymmetry in the profile results in new errors in estimated bias. This leaves operators of middle-and low-latitude stations with a significant challenge in their bias estimation, as pTEC can exceed 10 TECU at those locations [Lunt et al, 1999a;Mazzella, 2009]. Jan, 2009Jan, 2010Jan, 2011Jan, 2012Jan, 2013 Date 30 This mechanism has been extensively researched in the works of Lunt et al [1999aLunt et al [ , 1999b, Mazzella et al [2002], and Mazzella [2009].…”

Section: Plasmaspheric Electron Contentmentioning

confidence: 99%

“…This leaves operators of middle-and low-latitude stations with a significant challenge in their bias estimation, as pTEC can exceed 10 TECU at those locations [Lunt et al, 1999a;Mazzella, 2009]. Jan, 2009Jan, 2010Jan, 2011Jan, 2012Jan, 2013 Date 30 This mechanism has been extensively researched in the works of Lunt et al [1999aLunt et al [ , 1999b, Mazzella et al [2002], and Mazzella [2009]. While this is a significant concern for midlatitude observations, the absence of an appreciable plasmasphere in the polar cap region [Lunt et al, 1999a;Nsumei et al, 2008] debunks this as a mechanism through which the observed biases, and thus the ISR-GPS comparisons, should vary at the Resolute site.…”

Section: Plasmaspheric Electron Contentmentioning

confidence: 99%

“…While several techniques exist for determining these biases, one must take care in their application in regions outside their initial design [Lanyi and Roth, 1988;Ma and Maruyama, 2003;Ma et al, 2005;Rideout and Coster, 2006;Arikan et al, 2008]. Recent studies have attempted to characterize variabilities in these biases estimated through single-station approaches using real data and simulations [Ciraolo et al, 2007;Mazzella, 2009;Zhang et al, 2009;Brunini and Azpilicueta, 2010;Zhang et al, 2010;Conte et al, 2011;Coster et al, 2013]. These studies highlight the need to understand not only the nature of true bias variability but also the impact of the fundamental assumptions made in standard bias estimation techniques on bias estimation.…”

Section: Introductionmentioning

confidence: 99%

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The nature of GPS differential receiver bias variability: An examination in the polar cap region

2015

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While modern GPS receiver differential code bias estimation techniques have become highly refined, they still demonstrate unphysical behavior, namely, notable solar cycle variability. This study investigates the nature of these seasonal and solar cycle bias variabilities in the polar cap region using single‐station bias estimation methods. It is shown that the minimization of standard deviation bias estimation technique is linearly dependent on the user's choice of shell height, where the sensitivity of this dependence varies significantly from 1 total electron content unit (1 TECU = 1016 el m−2) per 4000 km in solar minimum winter to in excess of 1 TECU per 90 km during solar maximum summer. Using an ionosonde, we find appreciable shell height variability resulting in bias variabilities of up to 2 TECU. Comparing northward face Resolute Incoherent Scatter Radar (RISR‐N) measurements to a collocated GPS station, we find that RISR‐derived GPS receiver biases vary seasonally but not with solar cycle. RMS differences between bias estimation methods and observation between 2009 and 2013 were found to range from 2.7 TECU to 3.4 TECU, depending on method. To account for the erroneous solar cycle variability of standard bias estimation approaches, we linearly fit these biases to sunspot number, removing the trend. RMS errors after sunspot detrending these biases are reduced to 1.91 TECU. Also, these ISR‐derived and sunspot‐detrended biases are fit to ambient temperature, where a significant correlation is found. By using these temperature‐fitted biases we further reduce RMS errors to 1.66 TECU. These results can be taken as further evidence of temperature‐dependent dispersion in the GPS cabling and antenna hardware.

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“…4. Other research has found that the distribution of the plasmaspheric electron content along the meridional line has a significant effect on TEC and GPS instrumental bias estimation, and the accuracy of the instrumental bias can be improved by properly considering the distribution of the plasmaspheric electron content (Lunt et al, 1999;Mazzella et al, 2002Mazzella et al, , 2007Mazzella et al, , 2009Anghel et al, 2009;Carrano et al, 2009). Based on this improvement the distribution of the plasmaspheric electron content was estimated using GPS measurements (Mazzella et al, 2002(Mazzella et al, , 2007Anghel et al, 2009;Carrano et al, 2009).…”

Section: Results and Analysismentioning

confidence: 99%

Accuracy analysis of the GPS instrumental bias estimated from observations in middle and low latitudes

Zhang

et al. 2010

Ann. Geophys.

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Abstract. With one bias estimation method, the latituderelated error distribution of instrumental biases estimated from the GPS observations in Chinese middle and low latitude region in 2004 is analyzed statistically. It is found that the error of GPS instrumental biases estimated under the assumption of a quiet ionosphere has an increasing tendency with the latitude decreasing. Besides the asymmetrical distribution of the plasmaspheric electron content, the obvious spatial gradient of the ionospheric total electron content (TEC) along the meridional line that related to the Equatorial Ionospheric Anomaly (EIA) is also considered to be responsible for this error increasing. The RMS of satellite instrumental biases estimated from mid-latitude GPS observations in 2004 is around 1 TECU (1 TECU = 10 16 /m 2 ), and the RMS of the receiver's is around 2 TECU. Nevertheless, the RMS of satellite instrumental biases estimated from GPS observations near the EIA region is around 2 TECU, and the RMS of the receiver's is around 3-4 TECU. The results demonstrate that the accuracy of the instrumental bias estimated using ionospheric condition is related to the receiver's latitude with which ionosphere behaves a little differently. For the study of ionospheric morphology using the TEC derived from GPS data, in particular for the study of the weak ionospheric disturbance during some special geo-related natural hazards, such as the earthquake and severe meteorological disasters, the difference in the TEC accuracy over different latitude regions should be paid much attention.

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Plasmasphere effects for GPS TEC measurements in North America

Cited by 23 publications

References 17 publications

A Review of Higher Order Ionospheric Refraction Effects on Dual Frequency GPS

A Review of Higher Order Ionospheric Refraction Effects on Dual Frequency GPS

The nature of GPS differential receiver bias variability: An examination in the polar cap region

Accuracy analysis of the GPS instrumental bias estimated from observations in middle and low latitudes

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