Recommendations from

1
Recommendations from RT/NRT user requirements

• E-GVAP recommends IGS to support PPP strategy
  with high quality adequate products.
• The 'real-time' clocks will be interesting future
  product for using in GPS meteorology. NRT clocks
  for current needs.
• NRT GPS ZTD product for NWP
• Requirements for Costal real-time GPS network
  (next slide)
• For climate applications, no need for RT/NRT, but
  to produce the ZTD product with long-term
  stability, high quality, and reduced diurnal
  bias, to increase the temporal coverage, to
  co-locate with radiosonde stations, to increase
  the sfc met data.
• Desirable product additions NRT TEC with short
  term prediction (Grid or spherical harmonic
  coefficients and user algorithm), Sub daily EOP,
  Reference frame with periodical term included
• Possible improvements Clocks without
  discontinuities and to Supply satellite DCB in
  SP3

2
NASA Decision Project GPS-aided Real-Time
Earthquake and Tsunami (GREAT) Alert System
Coastal Real-Time GPS Network

• Technical Requirements
• Network design (10 km spacing)
• Signal frequency (1 Hz)
• Data accuracy (lt 1 cm)
• R/T GPS obits and clocks (10 sec)
• Data processing ( 2 min)
• GPS-inversion seafloor displacement tsunami
  energy estimation (2 min)
• Logistical Requirements
• International collaboration
• Systems integration

Existing GDGPS (JPL/NASA)
Add into GDGPS
3
From Historical Tsunamis to GPS Requirements
4
E-GVAP and IGS

• E-GVAP is very thankful for the services that IGS
  provides the geodetic community. They are vital
  to the NRT GPS ZTD product that we use in
  meteorology.
• For weather forecasting the GPS ZTD data must be
  available fast, and of a quality which is both
  good and does not fluctuate strongly in time.
• The timeliness issue is important and clearly
  influences ZTD data quality.

5
Conclusions/Recommendations

• GPS derived ZTDs are used operationally in
  Europe
• Due to steadily increasing number of
  operational GPS sites PPP strategy presents a
  promising outlook for future efficient
  GPS-meteorology. E-GVAP recommends IGS to support
  PPP strategy with high quality adequate products.
• The 'real-time' clocks will be interesting
  future product for using in GPS meteorology.
• For current needs E-GVAP encourages IGS to
  deliver clock products in near-real time
  (hourly) till the real-time IGS clocks will be
  available as products with sufficient quality

6
Summary quality of IGU prediction

• after decommission of satellite G29 (October,
  2008) there is no more significant difference in
  the standard orbit prediction performance.
• different pattern of the prediction can be seen
  during the eclipsing periods. We have to
  distinguish between satellites of old Block-IIA
  (fastly degrading) and new Block-IIR (modestly
  degrading) types.
• there are still 14 15 of old-type satellites
  active (45) G01, G03, G04, G05, G06, G08, G09,
  G10, G24, G25, G26, G27, G30, G32.
• accuracy codes are in most cases relevant for the
  prediction, but usually underestimated for
  Block-IIA during eclipsing periods and at the
  start of the maintenance periods.
• currently 1-9h prediction are at least necessary
  for NRT/RT usage
• shorter prediction will be appreciated especially
  due to old Block-IIA satellites, but mainly for
  the NRT/RT (global) PPP applications.
• Relevant question to ACs how simply they can
  provide the orbits upgraded every 3h (2h delay
  ?) with the same quality as of today ?
• (Even higher update rate could be requested for
  the PPP solutions).

7
Future Needs Recommendations on improving future
IGS products

1. To continuously produce the ZTD product and
   maintain its long-term stability and high quality
   
2. To reduce diurnal biases in the ZTD product
3. To improve and increase sfc-met data
4. To co-locate with radiosonde stations
5. To increase the spatial and temporal coverage

8
Desirable Product Addition/Upgrade

• NRT TEC with short term prediction
• in form of grid or spherical harmonic
  coefficients with a good user algorithm
  recovering correction values at arbitrary points
• Sub daily EOP
• will improve single epoch or short session
  (seconds to hours) applications
• Reference frame with well known periodical term
  included

Possible Improvements

• Clocks without discontinuities (done already?)
• Supply satellite DCB in SP3