Transcript Document 7609887

Need for a IGS real-time/near real-time
ionospheric product?
Tim Fuller-Rowell, Mihail Codrescu, Eduardo Araujo-Pradere
NOAA Space Weather Prediction Center and/or
CIRES University of Colorado
June 2-6, 2008
IGS Analysis Center Workshop
Effect of Solar X-rays on D-Region and HF Propagation.
Space Weather Prediction Center
National Weather Service
Boulder, Colorado
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24/7 Space Weather Operational Center
The nations official provider of real-time
space weather alerts, warnings, and products
June 2-6, 2008
IGS Analysis Center Workshop
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D-Region Absorption Product based on GOES X-Ray
Flux (SEC Product)
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The map shows regions affected by the increased D-region o
i nization resulting
from enhanced x-ray flux during magnitude X-1 Flare
Targeted Users and Parameters
• GPS positioning and navigation - iono TEC
correctors
• Satellite communications - iono irregularities
• HF communications - absorption, ray tracing
• Commercial Airlines
• Satellite environment, drag, and re-entry
• TEC, 3D Electron Density, Ne, , O/N2
• Specification and Forecast
June 2-6, 2008
IGS Analysis Center Workshop
US-TEC Target Users:
•Positioning and Navigation
community
•Collaboration between SWPC,
NGS, FSL, and NGDC
•Kalman filter over CONUS +
ground-based GPS data, IRI
background model, solve for
receiver biases
•15-minute cadence
•15 to 30 minute latency
•1.7 vertical - 2.4 slant TEC
unit accuracy (< 30 - 45 cm
delay at L1 frequencies)
June 2-6, 2008
IGS Analysis Center Workshop
Slant-Path TEC Maps
2-D maps of of slant path TEC over the CONUS
for each GPS satellite in view updated every 15
minutes
A
B
Sat. 1
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B
C
Sat. 14
A
B
C
A
Sat. 5
B
C
Sat. 29
C
Applications:
C
….etc
1. Ionospheric correction for single frequency GPS
2. Support dual-frequency integer ambiguity resolution for more rapid
decimeter and centimeter accuracy positioning
June 2-6, 2008
IGS Analysis Center Workshop
Ionospheric correctors for NGSOPUS in new RINEX format
US-TEC slant
TEC provides
ionospheric
correctors for
RINEX files
A
B
Sat. 29
C
June 2-6, 2008
IGS Analysis Center Workshop
VTEC Short-term Forecast
Using USTEC 10-day average to predict the
ionospheric behavior in to the next 1 to 2 hours.,
USTEC 10-day average
USTEC 15-min data
Now
Now-24 h
2
1
1 + 2
time
Now-24+t
t < 6hrs
1 – TEC in the 10-average between the value at now-24 h and now-24+t
2 – Departure of “now value” from the 10-day average.
June 2-6, 2008
IGS Analysis Center Workshop
Now+t
Capture gradients:
stationary “walls” of TEC
compromise integrity of
LAAS
Courtesy: Tom Dehel, FAA
TEC “walls”:
130 TEC units over 50 km
20 m of GPS delay;
walls move 100 to 500 m/s
SED?
1 TEC  ~16cm delay at L1
June 2-6, 2008
IGS Analysis Center Workshop
“wall”
Situational awareness:TEC Gradients
Use information on TEC gradients to estimate time interval needed to
record dual-frequency GPS data to achieve cm level positioning accuracy
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quiet ionospheric conditions
small gradients, shorter intervals
June 2-6, 2008
disturbed ionospheric conditions
- steeper gradients, longer intervals
IGS Analysis Center Workshop
Challenges: Large Gaps in Global Coverage
e.g. African Equatorial Longitudes
June 2-6, 2008
Coster and Foster
IGS Analysis Center Workshop
Sponsors: NASA, NSF, EOARD, ICTP, AFRL, AFOSR, ONR, CAWSES & COSPAR
IHY-Africa Workshop
June 2-6, 2008
IGS Analysis Center Workshop
Overview
of Proposed
Instrument
Arrays
Overview
of Instrument
Arrays
June 2-6, 2008
IGS Analysis Center Workshop
Expansion in global ground-based GPS networks
combined with space-based occultation to improve global specification
Europe (EUREF)
Canada
USA
IHY-Africa
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COSMIC occultations
June 2-6, 2008
IGS Analysis Center Workshop
ocean buoys
South
America
JPL
IGS Rapid Ionosphere  Real-time Ionosphere
Manuel Hernandez-Pajares et al
June 2-6, 2008
IGS Analysis Center Workshop
Future Direction
• Move from regional to multi-regional to global capability
• Move from < 100 to > 1000 real-time stations
• Modeling capability exists (e.g. JPL-GAIM, global USTEC,
USU/AFWA-GAIM)
• Sparse real-time data
• Forge collaborations and partnerships
• Leverage IGS/ICG/UNCOPUOS and ISES
• What is the value of accurate real-time ionospheric maps for IGS
applications?
• Natural consequence of improving accuracy of “rapid” iono maps
and 2nd order corrections
• Maps of ionospheric irregularities
June 2-6, 2008
IGS Analysis Center Workshop
June 2-6, 2008
IGS Analysis Center Workshop
The challenge in forecasting the ionosphere
and total electron content
1hr forecast 0.9
2 hr forecast 0.8
12hrs
June 2-6, 2008
IGS Analysis Center Workshop
24hrs
15 minute units
15 min intervals
CHAMP (400 km) OSEC:
Halloween storm
Mannucci et al. 2005
~50m delay at L1
June 2-6, 2008
IGS Analysis Center Workshop
Plasma Bubble Evolution
Mesoscale Model
Describes temporal development of plasma
structure
Uses nonlinear continuity and momentum
equations
Includes self-consistent electric fields
Coupled to ambient background
Estimates spectrum of density fluctuations
Retterer (1999)
Heavy
Fluid
Light
Fluid
June 2-6, 2008
IGS Analysis Center Workshop
Global Real-Time Network
June 2-6, 2008
IGS Analysis Center Workshop
Customers
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High Frequency (HF) Communication
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Single Frequency Positioning and Navigation
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single frequency potential sub-meter accuracy positioning
e.g. civil aviation, advanced vehicle tracking, potential for E911 improvements
Dual Frequency Positioning and Navigation
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ground-to-ground or air-to-ground communication
establish accurate maximum useable frequencies
support automatic link establishment systems
e.g. civilian aviation, maritime, frequency managers
decimeter accuracy 10-50 cm
e.g. real-time kinematic (RTK), autonomous transportation, off-shore drilling and
exploration
rapid centimeter accuracy positioning 1-2 cm
e.g. surveyors, possible InSAR applications
Satellite Communication
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specification and forecast of scintillation activity
e.g. satellite operators, drilling companies
June 2-6, 2008
IGS Analysis Center Workshop