Assimilating Data Into Ionospheric Models: The Real-Time Revolution Anthony Mannucci, JPL Brian Wilson, JPL George Hajj, JPL, USC Lukas Mandrake, JPL Xiaoqing.
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Assimilating Data Into Ionospheric Models: The Real-Time Revolution
Anthony Mannucci, JPLBrian Wilson, JPL George Hajj, JPL, USCLukas Mandrake, JPLXiaoqing Pi, JPL, USCChunming Wang, USCGary Rosen, USC
National Reconnaissance Office Technology SeminarJuly 11, 2005
JPL/USCGAIM
[Tony.Mannucci@jpl.nasa.gov]
Part I
NRO Technology Seminar July 11, 2005
0
5
10
15
20
25
30
Middle Latitude(30-60 degrees)
Low Latitude(30S to 30N)
Solar Minimum
Solar Maximum
Daytime Maximum Ionospheric Delays(Vertical Incidence)
Troposphere
Density Comparison:Troposphere ~1x10-3 g/cm3
Ionosphere ~2x10-14 g/cm3
Motivation: Ionospheric Effect on GPS Signals
Iono
Tropo
GPS
Receiver
350 km
1 km
NRO Technology Seminar July 11, 2005
Ionospheric Delay Versus Frequency
1 TECU = 1016 el/m2
Delay = 40.3 TEC/f2
Leading term only…
NRO Technology Seminar July 11, 2005
Raypath Bending
Radio signal path depends on detailed ionospheric vertical and horizontal structure
• HF communications• Over-the-horizon radar
NRO Technology Seminar July 11, 2005
Raypath Bending Versus Frequency
Approximate FormulaMillman and Reinsmith
Elevation Angle:
App
aren
t Ele
vatio
n C
hang
e (D
egre
es)
NRO Technology Seminar July 11, 2005
NASA Application: Deep Space Tracking
S-band 2 GHzX-band 8 GHz
• Effect of media on tracking observables must be calibrated
• How to do it robustly and accurately?
NRO Technology Seminar July 11, 2005
• Remove “average” delay– Climatology (physics or data-based)– Not sufficiently accurate due to “weather”
• Self-calibrate– Use dual-frequency tracking observables
• Acquire real-time measurements– Most accurate approach– Requires measurements and model that is updated
by data
Calibrating Media Effects
NRO Technology Seminar July 11, 2005
Improving Global Delay Estimates
Iijima et al., Journal of Atmospheric and Solar-Terrestrial Physics, 1999
Ionospheric Specification and Determination Workshop, JPL 1998
Non-data driven (IRI-95)Data driven (GIM)
Global GPS Receiver Network Global Ionospheric Map
Low Solar Activity (1998)
NRO Technology Seminar July 11, 2005
Improving Vertical Profiles
Six-satellite COSMIC constellationLaunch late 2005
Low-Earth OrbiterGPS
3000 profiles/day
ElectronDensityProfile
COSMIC coverage
NRO Technology Seminar July 11, 2005
Latency of Electron Density Profiles
COSMIC data latency (courtesy of Chris Rocken, UCAR)
NRO Technology Seminar July 11, 2005
USC/JPL Global Assimilative Ionosphere Model (GAIM)
NRO Technology Seminar July 11, 2005
Ionospheric and Atmospheric Remote Sensing Group at JPL
• Global Ionospheric TEC Mapping (GIM)– First ever global TEC map (1993) – SATLOC wide-area differential GPS (1996) – real-time, regional– FAA wide-area augmentation system 1996-on– Naval Oceanographic Office: ionosphere calibrations for GEOSAT
Follow-On mission daily– By-product: provide satellite calibrations (Tgd) to GPS Project– By-product: algorithm adopted by DoD contractors
• Ionospheric data systems for R&D– Real-time/near real-time TEC products from GPS global network– GPS TEC sent to Air Force Weather Agency
• Model assessment– Ionospheric Network Analysis– Data-Driven Ionospheric Calibration Experiment (DICE)
• Model development – Global Assimilative Ionosphere Model– AFOSR/ONR-sponsored MURI 5-year development program
• C/NOFS augmentation: C/NOFS data into GAIM
NRO Technology Seminar July 11, 2005
• AFRL Collaboration (Task manager: Bill Borer)• C/NOFS satellite: Goal is forecast of scintillation• Investigating use of GAIM for background density field
• Critical for accurate forecasts
• Input C/NOFS Datatypes:• GPS occultation• In situ density• Vector Electric fields, vertical drift velocity• Tri-band beacon (ground-LEO TEC links)
• Close collaboration• Source code transfer• Jointly-conducted analysis• Technology transfer (source code, expertise, data sets…)
C/NOFS Augmentation Effort
NRO Technology Seminar July 11, 2005
Accurate deep-spacenavigation
Civil-aircraftnavigation/landing
Ocean topographySatellite instruments
Communications, Navigation,
Radar, Surveillance
New measurements
Applications
• Deep-space tracking
• Global-scale calibration
• Space environment
Applications of Data-Based Ionospheric Calibrations
• Scientific Research
• Regional-scale calibration
Requirements Driver Products/Obs• Line-of-sight
slant delay
• Regional TEC maps
• Error bounds
• Global TEC maps• Tracking and
sensor corrections
• GPS ground and space, in-situ, TEC beacons, sondes, UV GAIM
NRO Technology Seminar July 11, 2005
JPL Products and Users
Global Ionosphere Maps(Vertical TEC or Delay)
Near Real-timeTotal Electron Content
Global AssimilativeIonosphere Model
Algorithms
Studies
Electron Density Profiles
FAA
Deep space navigation
GEOSATFollow-on
GPS augmentation
Wide-areaLocal-area
Ionospheric Network Analysis
DICE Data-driven iono cal expt
Hourly & 5-min TEC to
AFWA
Orbits for TDRSS etc.
Space Env Sensor Study
Space science (proposed)
Develop GAIM @
USC & JPL
CNOFSaugmentation
DoD
Products
DoD
DoD
NOAA
Navy
AFOSR/ONR
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