# Presentation: 761540

## 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

- IGS Analysis Center Workshop

- June 2-6, 2008

## Space Weather Prediction CenterNational Weather ServiceBoulder, Colorado

- 24/7 Space Weather Operational Center
- The nations official provider of real-time space weather alerts, warnings, and products

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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)

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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**

- Applications:
- 1. Ionospheric correction for single frequency GPS
- 2. Support dual-frequency integer ambiguity resolution for more rapid decimeter and centimeter accuracy positioning

- Sat. 1

- Sat. 5

- Sat. 14

- Sat. 29

**...****.****etc**

- A

- A

- A

- A

- B

- B

- B

- B

- C

- C

- C

- C

- C

- IGS Analysis Center Workshop

- June 2-6, 2008

## Ionospheric correctors for NGS-OPUS in new RINEX format

- US-TEC slant TEC provides ionospheric correctors for  RINEX files

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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

- time

- IGS Analysis Center Workshop

- June 2-6, 2008

## Capture gradients:stationary “walls” of TEC compromise integrity of LAAS 

- TEC “walls”:
- 130 TEC units over 50 km
- 20 m of GPS delay;
- walls move 100 to 500 m/s

- SED?

- “wall”

- 1 TEC   ~16cm delay at L1

- Courtesy: Tom Dehel, FAA

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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

**quiet ionospheric conditions**
**small gradients, shorter intervals**

**disturbed ionospheric conditions **
**- steeper gradients, longer intervals**

- IGS Analysis Center Workshop

- June 2-6, 2008

## Coster and Foster

**Challenges: Large Gaps in Global Coverage **
**e.g. African Equatorial Longitudes**

- IGS Analysis Center Workshop

- June 2-6, 2008

## Sponsors: NASA, NSF, EOARD, ICTP, AFRL, AFOSR, ONR, CAWSES & COSPAR

***Sponsors: NASA, NSF, EOARD, ICTP, AFRL, AFOSR, ONR, CAWSES & COSPAR***

**IHY-Africa Workshop**

- IGS Analysis Center Workshop

- June 2-6, 2008

- Overview of Proposed Instrument Arrays

- Overview of Instrument Arrays

- IGS Analysis Center Workshop

- June 2-6, 2008

## Canada

-  COSMIC occultations

- USA

- Europe (EUREF)

- JPL

- Expansion in global ground-based GPS networks

- South
- America

- combined with space-based occultation to improve global specification

-  ocean buoys

- IHY-Africa

- IGS Analysis Center Workshop

- June 2-6, 2008

## IGS Rapid Ionosphere  Real-time Ionosphere

**IGS Rapid Ionosphere ******** Real-time Ionosphere**

- Manuel Hernandez-Pajares et al

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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

- IGS Analysis Center Workshop

- June 2-6, 2008

## Slide 16

- June 2-6, 2008

## The challenge in forecasting the ionosphere and total electron content

**15 minute units**

- 12hrs

- 24hrs

- 15 min intervals

- 1hr forecast 0.9
- 2 hr forecast 0.8

- IGS Analysis Center Workshop

- June 2-6, 2008

## CHAMP (400 km) OSEC: Halloween stormMannucci et al. 2005

- ~50m delay at L1

- IGS Analysis Center Workshop

- June 2-6, 2008

## 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)

**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)**

**Plasma Bubble Evolution**

- IGS Analysis Center Workshop

- June 2-6, 2008

**Notes:**
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## Global Real-Time Network

- IGS Analysis Center Workshop

- June 2-6, 2008

## Customers

**High Frequency (HF) Communication **
**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**
**Single Frequency Positioning and Navigation**
**single frequency potential sub-meter accuracy positioning**
**e.g. civil aviation, advanced vehicle tracking, potential for E911 improvements**
**Dual Frequency Positioning and Navigation**
**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**
**specification and forecast of scintillation activity**
**e.g. satellite operators, drilling companies**

- IGS Analysis Center Workshop

- June 2-6, 2008