Report on SBAS Ionospheric Working Group

Report on SBAS Ionospheric Working Group

Todd WalterStanford University

http://waas.stanford.edu

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SBAS Ionospheric Working Group

Chartered under the IWG to investigate ionospheric issues that jointly affect SBAS providers

Led by Bertram Arbesser-Rastburg (ESA) and Patricia Doherty (Boston College)

First meeting in Canada in 1999 Attendees from Europe, U.S., and Canada Later meetings also included representatives from

Japan, India, and Brazil 19 meetings held to date (one to two a year) Most recent meeting – April 2012 at ITCP in Trieste in

conjunction with African Outreach Workshop Next meeting in two weeks in Bath, England

Ionospheric Working Group Major Activities

Facilitate interaction of ionospheric scientists supporting SBASExchange of data and ideasCoordinate research and data collectionHarmonize threats and threat models

Produced two major White Papers “Ionospheric Research Issues for SBAS”

Released Feb 2003 on ionospheric effects “Effect of Ionospheric Scintillation on GNSS”

Released Nov. 2010 on scintillation

Available at: http://waas.stanford.edu3

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Current Topics of Discussion Monitoring networks Identification of ionospheric events Effects of recent storms Ionosphere modeling Correlation of scintillation fading on L1, L2,

and L5 Proposed MOPS change for scintillation Progression of solar cycle 24

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Solar Cycle 24

Next Meeting Agenda (1 of 2)

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Friday, 2013-07-12 09:00 Opening, Welcome, Approval of Agenda SBAS Status Reports 09:05 WAAS Status (Todd Walter) 09:25 EGNOS status (Stefan Schlueter) 09:45 GAGAN Status (P.V. Rama Rao) Plans for new Augmentation systems 10:00 Activities with ASECNA in Africa (Stefan Schlueter) 10:15 GBAS possibilities for Brazil (Ivan Kantor) Operational experience 10:50 Scintillation on GPS L1, L2 & L5 signals (Charles Carrano) 11:10 Impact of Ionosphere on EGNOS (Angeline Billot) 11:30 Scintillation effects on WAAS at solar max (Eric Altshuler) 11:50 EGNOS open service iono model (Roberto Prieto Cerdeira) 12:10 Comparison of EGNOS, global maps & experimental data at position domain (Claudia

Paparini) 12:20 Ongoing SBAS / Ionospheric training at ICTP (Sandro Radicella) Scintillation Observations and Modeling 14:00 Scintillation results from MONITOR Project (Yannick Beniguel) 14:20 Latest developments in GISM Scintillation model (Yannick Beniguel) 14:40 Scintillation observations in India (P.V. Rama Rao) Reports on Experimental Campaigns 15:00 Ionospheric scintillation and TEC studies over Brazil using GNSS [Eurico de Paula) 15:20 ESA Ionospheric activities at low latitudes (Roberto Prieto Cerdeira)

Next Meeting Agenda (2 of 2) Saturday, 2013-07-13 Experiments Continued 09:00 LISN Status (Pat Doherty) 09:20 LISN Processing and prelim results (Eric Altshuler) 09:40 IGS MGEX campaign (Richard Langley) 10:00 Comparison of modern scint-mon receivers (Keith Groves) Ionospheric Storms 10:15 New indicator for definition of iono storm conditions (Jaume Sanz) 10:50 Discussion on way forward Next Meeting A.o.B. 12:00 Close of meeting

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Summary

SBAS Ionospheric Working group continues to meet once to twice a year

Current focus on: addressing recommendations of Scintillation

White Paper collecting (and making available) data sets

for sharing planning updates of white paper as results

provide new information Next meeting in 2 weeks:

University of Bath, after the Beacon Satellite Symposium

Recent Ionospheric Effects on WAAS

Todd WalterStanford University

http://waas.stanford.edu

Summary of EffectsSince January 2013 there has been

one minor ionospheric storm that impacted WAAS service over CONUSJune 1, 2013

A few minor storms have had some impact over Alaska and/or CanadaMarch 17 & 27, May 16, 19, 25, & 26, &

June 7, 2013

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Kp

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Coverage (Storms)

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Nominal Mar. 17

Mar. 27 June 1

Coverage

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Apr. 4 June 7

Loss due to PRN 18 being out of service, not to the ionosphere

Largest Kp day of the quarter (Kp = 7)

Presented to: DistributionBy: Bill WannerDate: June 3, 2013

Federal AviationAdministrationEffect on WAAS from

Iono Activity on June 1, 2013

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Kp Index Chart

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Coverage vs. Time Charts

• This event affected WAAS early in the day (GMT time) on June 1

• For a comparison of a ‘good’ day and the coverage on June 1 the following two slides shows CONUS and Alaska coverage for June 1 and June 2

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Coverage vs. Time Charts – CONUS – May 31 vs June 1

May 31, 2013 June 1, 2013

Iono activity from about 03:00 – 09:00 GMT

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Coverage vs. Time Charts – Alaska – May 31 vs June 1

May 31, 2013 June 1, 2013

Iono activity from about 03:00 – 09:00 GMT

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LPV-200 Coverage – June 1, 2013

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RNP 0.1 Coverage – June 1, 2013

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Accuracy – WAAS User• Accuracy was higher on June 1 than other days

– Both horizontal and vertical position errors were higher• Next two charts show the HPE and VPE, respectively, at the

Seattle WAAS reference station on June 1 and June 2– Seattle is used as an example

• The maximum HPE at Seattle is normally less than 1.5 meters– The maximum HPE was about 2.9 meters on June 1– HPL was 22.5 meters at the time of the maximum error

• HPE/HPL ratio = .13

• The maximum VPE at Seattle is normally less than 3 meters– The maximum VPE was about 6.8 meters on June 1– VPL was 25.3 meters at the time of the maximum error

• VPE/VPL ratio = .27, the highest of all WAAS sites on June 1 but VPE was still very well bounded by VPL

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Accuracy – GPS User• The following table shows a comparison of the calculated accuracy

for a single frequency L1 SPS user and a position solution using dual frequency (L1 and L2) for several sites:

Site Name

Dual Frequency Horizontal Position

Error (m)

Dual Frequency Vertical Position

Error (m)SPS Horizontal

Position Error (m)SPS Vertical

Position Error (m)

Cold Bay 3.239 3.991 6.857 9.308

San Jose del Cabo 3.035 3.974 5.576 15.317

Los Angeles 2.903 5.079 4.786 11.373

Oakland 3.069 6.473 5.961 10.235

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EGNOS Coverage

• Since EGNOS is publishing LPV procedures we took a look at the 24 hour coverage plot

• The plot is based on data collected from the Atlantic City and Bangor NSTB reference receivers– Data from ENGOS GEO PRN 120

• On the next slide the top plot is WAAS and EGNOS LPV coverage on June 1 and the bottom plot is June 2– Little impact to EGNOS LPV coverage due to the iono activity on June

1 when compared to June 2• MSAS is included in the plot but there is no LPV approved

procedures that use MSAS

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WAAS/EGNOS Coverage June 1-2

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Conclusion

• Iono activity on June 1 caused a loss of LP, LPV, and LPV-200 coverage in the WAAS service volume

• Accuracy for a WAAS and single frequency GPS user was increased on June 1 compared to June 2

• EGNOS coverage was minimally impacted due to this iono event