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

Zhang, D. H.; Zhang, W.; Li, Q.; Shi, Liqin; Hao, Yongqiang; Xiao, Zuo

doi:10.5194/angeo-28-1571-2010

Cited by 61 publications

(34 citation statements)

References 29 publications

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“…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%

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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Section: Introductionmentioning

confidence: 99%

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

2015

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“…In this case, the model's error in terms of both MAE and RMSE is comparable to 3 TECu that in turn, is comparable to the TEC measurement error at middle latitudes (e.g. Zhang et al, 2010 and references therein). Significant improvement (>10%) over climatology is recorded in both cases.…”

Section: Swif's Empirical Formulation For the Vtec Forecastmentioning

confidence: 71%

A new short-term forecasting model for the total electron content storm time disturbances

Tsagouri

Koutroumbas

Elias

2018

J. Space Weather Space Clim.

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-This paper aims to introduce a new model for the short-term forecast of the vertical Total Electron Content (vTEC). The basic idea of the proposed model lies on the concept of the Solar Wind driven autoregressive model for Ionospheric short-term Forecast (SWIF). In its original version, the model is operationally implemented in the DIAS system (http://dias.space.noa.gr) and provides alerts and warnings for upcoming ionospheric disturbances, as well as single site and regional forecasts of the foF2 critical frequency over Europe up to 24 h in advance. The forecasts are driven by the real time assessment of the solar wind conditions at ACE location. The comparative analysis of the variations in foF2 and vTEC during eleven geomagnetic storm events that occurred in the present solar cycle 24 reveals similarities but also differences in the storm-time response of the two characteristics with respect to the local time and the latitude of the observation point. Since the aforementioned dependences drive the storm-time forecasts of the SWIF model, the results obtained here support the upgrade of the SWIF's modeling technique in forecasting the storm-time vTEC variation from its onset to full development and recovery. According to the proposed approach, the vTEC storm-time response can be forecasted from 1 to 12-13 h before its onset, depending on the local time of the observation point at storm onset at L1. Preliminary results on the assessment of the performance of the proposed model and further considerations on its potential implementation in operational mode are also discussed.

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“…We used the data with satellite elevation larger than 30 • to minimize the errors caused by converting slant TEC into vertical TEC and the multipath effects. B s r was the main error source of the ionospheric TEC deriving from GPS observation and could reach up to several TECU (1 TECU = 10 16 electrons m −2 ) or even larger than the real slant TEC (Sardón and Zarraoa, 1997;Zhang et al, 2010), and the effect of this biases must be removed to get the absolute measurements of TEC. Here, we eliminated the B s r by combining the vertical TEC time series (VTEC) with the JPL GIM data which was interpolated in both space and time.…”

Section: Multichannel Maximum-entropy Methodsmentioning

confidence: 99%

Global propagation features of large-scale traveling ionospheric disturbances during the magnetic storm of 7~10 November 2004

et al. 2012

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Abstract. Larger-scale traveling ionospheric disturbances (LSTIDs) were studied using the total electron content (TEC) data observed from global GPS network in the regions of North America, Europe, and East Asia during the magnetic storm of 7∼10 November 2004. 4 LSTID events were detected in North America, 4 in Europe, and 3 in East Asia. The parameters of the 11 LSTID events, such as the propagation azimuth (the angle with respect to north, taking clockwise as positive), horizontal phase velocity and damping rate were determined. Our results showed two new propagation features of the LSTIDs. One was the latitudinal dependence of the LSTIDs' propagation azimuths. The LSTIDs tended to deflect more to west from south as they propagated to lower latitudes, which indicated that the Coriolis force was one of the main causes of the LSTIDs' southwestward deviation. The other was the different mean horizontal phase velocities of LSTIDs among different regions. The mean horizontal phase velocity of LSTIDs was 422 ± 36 m s −1 in North America, 381 ± 69 m s −1 in Europe, and 527 ± 21 m s −1 in East Asia, respectively. The results also indicated that the amplitudes of LSTIDs decreased during their propagation for every event, and the daytime damping rates were more than 1 time larger than the nighttime ones due to different ion drag between daytime and nighttime. The source regions of the LSTIDs were likely to be located between geomagnetic latitudes of 68 • N and 62 • N in North America, and between 65 • N and 57 • N in Europe, according to the variation of magnetic H component observed in these two regions.

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

Cited by 61 publications

References 29 publications

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

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

A new short-term forecasting model for the total electron content storm time disturbances

Global propagation features of large-scale traveling ionospheric disturbances during the magnetic storm of 7~10 November 2004

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