1. TIMED-GUVI for Nowcasting R. A. Goldberg and J. B. Sigwarthby
R. A. Goldberg and J. B. Sigwarth
NASA/GSFC
and
L. J. Paxton
JHU/APL
R2O Workshop. NASA/GSFC
15-18 October 2007

2. Approach Provide an introduction to the TIMED-GUVI instrument.
Define the region of the atmosphere measured by GUVI.
Define some of the complexities of the atmosphere which complicate studies using GUVI data.
Demonstrate where GUVI becomes a useful and important instrument for measurement and prediction.
Show how GUVI could be applied to nowcasting.

3. SABER latitudinal coverage
The TIMED Satellite
TIMED: Thermosphere, Ionosphere, Mesosphere Energetics & Dynamics
Mission launched on December 7, 2001.
Circular Orbit, 625 km, 74.1° Inclination.
Data available since January 25, 2002.
4 instruments: GUVI, SEE, TIDI, SABER.
SABER latitudinal coverage
Example of an orbit

4. GUVI is Designed to Produce Space Environment Products
for Nowcasting of the Mesospheric- Thermospheric-
Ionospheric (MTI) Environment
GUVI was launched from Vandenberg AF Base
on December 7, It has been operating
continuously since launch.
GUVI measures the far ultraviolet emissions from
the Earth’s upper atmosphere.
GUVI software can convert the radiance observations
into sensor data records for context and imaging
and into environmental data records for use by
operators interested in nowcasting of space weather.
The key products are
Electron Density Profiles (day and night)
Neutral Density Profiles (day)
Auroral Energy Deposition Rate (day and night)
Auroral Oval Location (day and night)
TIMED Delta II Launch, 12/07/01

5. GUVI is a Hyperspectral Imager
Point is we get disk images an the limb view - limb view gives us altitude information…altitude information is a driver for the remote sensing requirements on NPOESS

6. GUVI Focuses on the Space Weather in the Earth’s Upper Atmosphere
GUVI Regime
The FUV covers the altitude range from about 110 km to (for SSUSI) 520 km. The point is this is the region where you get the ionosphere and all of its structure.
This is the region where radio signals are affected by the ionosphere and satellite’s experience atmospheric drag.

7. How Predictable is the State of the Upper Atmosphere?

8. Add the Earth’s Magnetic Field

9. Put the System in Geospace: Add the Solar Wind and Interplanetary Magnetic Field

10. Add Geomagnetic Storms Which Occur Throughout the 11 year Solar Cycle.

11. For RF Users Scintillation is a Significant Concern

12. Ionospheric Disturbances are Created in the Auroral Region and Propagate Toward the Equator

13. The Challenge is to Capture the Physics in a Way that Addresses Related Needs
GUVI data are recorded on S/C and downlinked
Data reformatted for processing
Calibration applied to convert from counts to radiance
Each pixel is located on the Earth
Radiance data are regridded into superpixels - Sensor Data Records
(SDR or LC1)
Don’t need to show – colors are formed on the spacecraft and are user definable.
These are the things that happen in the SSUSI software at AFWA
Regridding is done because there is an overlap from scan to scan
Pixels are separated by region: Day, Night, and Aurora
Each regions data are processed to produce the
Environmental Data Records (EDR or L2)
GUVI data are ingested by models to produce higher level forecast and nowcast products (L3)

14. GUVI EDRs
GUVI can provide intensity maps and environmental parameters to a user.
The SDRs are calibrated and geolocated and will be ingested by GAIM.
EDRs have been processed to produce “space weather” products that can provide space situational awareness.
We are in the middle of the cal/val effort – the SSUSI data will be available for operational use starting in April 2005.
Cross-hatched area indicates GUVI coverage on one orbit - over 10,000 ionospheric observations per orbit.

15. The Position and Extent of the Auroral Oval Is Important
GUVI swath
Current ovation model
Auroral oval location
GUVI provides a day/night all-weather, all conditions capability to image the oval.
The auroral maps the location of ionospheric disturbances – these disturbances will create “blind spots” for over-the-horizon radars.
Current scenarios put aircraft and missile tracks through the auroral region where ionospheric disturbances exist, the IR background clutter is enhanced and ionospheric disturbances are created that propagate down to lower latitudes.
Current operational models for forecasting the position of the oval are “data starved”. GUVI would decrease the revisit time for imaging the oval – especially important during disturbed conditions.

16. Geomagnetic Disturbances Cause Scintillation Events Down to Mid- and Low Latitudes
Disturbance seen in Magnetic Field
- SYM-H (or Bz)
S4 Amplitude Scint - L BAND
S4 Amplitude Scint - UHF A B)
(U) Fig 5. 6 S4 Scintillations as measured over Westford, MA July 2000 in panels 2 & 3. Note that the geomagnetic index SYM-H in panel 1 is much smoothed, does not match the time response of the measured scintillation.
[ Source: Basu, Dec ]
Limitations in TEC( iono activity) & SYM-H ( magnetic activity)
Drift Velocity m/s of electrons
Source: Basu, 2002
Geomagnetic storms, solar flares, and ionospheric disturbances routinely create widespread intense scintillation for periods of hours, or days. These can reach mid- and low latitudes. These events have a high degree of short term predictability.

17. Basic Research Projects Told Us that Our Ionospheric Images Should Map Scintillation
Correlation between nightglow image, TEC and scintillation. Data collected from a collocated imaging system and GPS SCINTMON on the Haleakala Volcano on Maui, HI. Scintillations are seen (as an increase in the S4 index in the top-right panel) when the look direction from the receiver to the satellite (the green square on each image) passes through the dark region of the image (from airglow.csl.uiuc.edu/Facilities/RENOIR/)

18. One of the Current Challenges is to Predict Ionospheric Scintillations on a Global Basis
Illustration of existing and proposed SCINDA sites from
Observations from ground-based sites of the amount of scintillation in the signal received from an orbiting beacon provides a local measure - but you have to have a ground station there.
Note the lack of current coverage in areas of concern as well as lack of mid-latitude coverage.

19. GUVI Observations Show the Location and Extent of Ionospheric Irregularities
In this image individual orbits of data are shown mapped onto the globe.
The bright bands are the equatorial ionization crests from the Appleton anomaly.
Smaller scale dark bands are equatorial bubbles – holes in the ionosphere that affect HF propagation.
These ionospheric bubbles are one of the most important phenomena to be investigated by the upcoming C/NOFS mission.
GUVI and C/NOFS will be working together to develop a global forecasting capability.
The existence of scintillation has an impact on the ability of aircraft to communicate, navigate or maintain surveillance.
Each bright band is one orbit of SSUSI data.
The magnetic equator is the dotted curve in the center of the image on either side are the equatorial arcs – they are controlled by the magnetic field.
We plan to develop scintillation techniques with C/NOFS and then apply those to other areas.
The images are shown in an intensity scale that reflects Total Electron Content (TEC)

20. Far Ultraviolet Observations Actually Map Where Scintillation Occurs
Observed scintillations
WBMOD and GUVI images of the equatorial ionosphere. The GUVI images show the location of ionospheric irregularities not adequately predicted by WBMOD.

21. What GUVI Can Provide for Space Weather Operators
It can provide the global context at fixed local solar times (neutral atmosphere and ionospheric parameters).
It can provide the location and extent of bubbles.
It can map composition changes.
It can determine the locations of the ionization crests, their magnitude, and the altitude profile of the mid- and low-latitude ionosphere.
It can provide 3D images of the bubbles.
It can provide high latitude inputs and maps of auroral activity.
Near realtime data is now being provided to the Air Force.
Image of the aurora over the USA, during the October 2003 superstorm.
This is a daylight image, obtained in the far ultraviolet.

22. One Can Bridge the Gap Between Basic Research and Applications (R2O)
The GUVI program has benefited from the interplay and exchange between programs that seek to develop a deeper understanding of the upper atmosphere (NASA and NSF funding) and the needs of our sponsors.
Its ability to go from basic research to production of operational satellites and/or instruments to applications products has been demonstrated.
New products have been demonstrated that could be incorporated in the operational environment:
Better prediction of the auroral oval location.
Images of the actual location and extent of ionospheric bubbles.
New ways of viewing these bubbles that could be incorporated into ionospheric propagation codes.
Real-time measurements of the neutral atmosphere.