glotec
play

GLOTEC Global real-time TEC map Navigation System Reliability - PDF document

Feb 28, 2023 •198 likes •530 views

GLOTEC Global real-time TEC map Navigation System Reliability Forecast 1/8/2002 Alpbach Summer School 2002 / Team Nina 1 Contents Introduction Satellite Navigation Systems Goals of GLOTEC Details Nowcast Segment

  1. GLOTEC Global real-time TEC map Navigation System Reliability Forecast 1/8/2002 Alpbach Summer School 2002 / Team Nina 1 Contents � Introduction � Satellite Navigation Systems � Goals of GLOTEC � Details � Nowcast Segment � Forecast Segment � Operative Space Segment � Broadcast Infrastructure � Cost guesstimate, schedule � Summary 1/8/2002 Alpbach Summer School 2002 / Team Nina 2

  2. Mission Statement Geomagnetic storms threaten the integrity of satellite navigation (SN) systems. More specifically, the users of single-frequency SN receivers experience loss of accuracy in the calculation of their position. This is due mainly to the existing systems’ inability to fully correct for ionospheric delay during severe space weather conditions. GLOTEC is the solution for these users. Our primary goal is to increase the integrity of satellite navigation systems by Providing improved ionospheric delay corrections and � Providing an early warning system based on reliable � forecasts of geomagnetic storm activity 1/8/2002 Alpbach Summer School 2002 / Team Nina 3 Goals � Nowcast � Total Electron Content (TEC) coverage � Error range 15:23 UT � Forecast ! � expected level of ionospheric disturbances 18:11 UT 1/8/2002 Alpbach Summer School 2002 / Team Nina 4

  3. Users � Primary users: � Users of Single Frequency Nav. Receivers Real time TEC � Aircraft � Communication companies QOS prediction � Space Industry � Pipeline companies � Power companies � Secondary users � Scientists (space weather, geophysics, biology) � Amateur radio 1/8/2002 Alpbach Summer School 2002 / Team Nina 5 Contents � Introduction � Satellite Navigation Systems � Goals of GLOTEC � Details � Nowcast Segment � Forecast Segment � Operative Space Segment � Broadcast Infrastructure � Cost guesstimate, schedule � Summary 1/8/2002 Alpbach Summer School 2002 / Team Nina 6

  4. GPS working principle (1) � 24 satellites � Orbit period 12h � 6 orbital planes, inclined 55deg � 5–8 satellites visible at any given time � Synchroneous clocks on board the satellites 1/8/2002 Alpbach Summer School 2002 / Team Nina 7 GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 8

  5. GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 9 GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 10

  6. GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 11 GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 12

  7. GPS working principle (2) 1/8/2002 Alpbach Summer School 2002 / Team Nina 13 Real World Situation (1) � Geometrical restrictions ) ) ) ) ) ) ) ) ) � Blockage � Multi-path ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ( ( ( ( ( 1/8/2002 Alpbach Summer School 2002 / Team Nina 14

  8. Real World Situation (2) ) ) ) ) ) ) ) ))))))) ) ) ) ) ) ) ) � Atmospheric/Ionospheric � Dispersion (60m) � Scintillations (0m – inf) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) � Attenuation through refraction ) ) ) ) � Faraday rotation ) ) 1/8/2002 Alpbach Summer School 2002 / Team Nina 15 Dispersion / Scintillation lost track r 1 , t 1 Magnetosphere Ionosphere dispersion r ‘ 1 , t‘ 1 dispersion + scintillation Storm conditions: Quiet conditions: Warning needed Correction needed 1/8/2002 Alpbach Summer School 2002 / Team Nina 16

  9. Contents � Introduction � Satellite Navigation Systems � Goals of GLOTEC � Details � Nowcast Segment � Forecast Segment � Operative Space Segment � Broadcast Infrastructure � Cost guesstimate, schedule � Summary 1/8/2002 Alpbach Summer School 2002 / Team Nina 17 GLOTEC goals (1) � Nowcast: Real-time global TEC map + error range � Compensate for time delay Movie courtesy of B. Arbesser-Rastburg 1/8/2002 Alpbach Summer School 2002 / Team Nina 18

  10. GLOTEC goals (2) � Forecast based on space weather: expected level of ionospheric disturbances � Predicts future Quality of Service (QOS) ! 18:11 UT 1/8/2002 Alpbach Summer School 2002 / Team Nina 19 Contents � Introduction � Satellite Navigation Systems � Goals of GLOTEC � Details � Nowcast Segment � Forecast Segment � Operative Space Segment � Broadcast Infrastructure � Cost guesstimate, schedule � Summary 1/8/2002 Alpbach Summer School 2002 / Team Nina 20

  11. GLOTEC data flow (overview) MODEL A History TEC(t 1 ) Statistics TEC(t 1 ) TEC USERS Measurements interpolate data points onto global map On global, uniform grid ST data (t 1 ) ST data ST data History ST data QOS(t 1 +X) MODEL B Statistics USERS prediction 1/8/2002 Alpbach Summer School 2002 / Team Nina 21 Nowcast Segment 1/8/2002 Alpbach Summer School 2002 / Team Nina 22

  12. TEC Nowcast 16 GLOTEC satellites Ground Network End User -GLOTEC -USA (WAAS) Measured TEC -Europe (EGNOS) -Japan (MSAS) •Global TEC •Error estimates Solar sunspot NeQuick model for Global TEC number (or F 10.7 ) GLOTEC prediction STORM model center a p index 1/8/2002 Alpbach Summer School 2002 / Team Nina 23 TEC Models � NeQuick � A quiet-time ionospheric model � Developed at ICTP Abdus Salam Institute (Italy) and the University of Graz (Austria) � Input: � Historical database � Total sunspot number estimated from F 10.7 � Current time 1/8/2002 Alpbach Summer School 2002 / Team Nina 24

  13. TEC Models � STORM � A simple empirical storm-time ionospheric model � Developed at NOAA � Input: � Previous 30 hours of a p index � Archive of ionosonde measurements from a number of storms � Provides good error estimates 1/8/2002 Alpbach Summer School 2002 / Team Nina 25 Making the global TEC map � Map is primarily based on satellite/ground network TEC measurements � NeQuick or STORM model values are fitted to the true measurement values � Locations not covered by TEC measurements are given values from the fitted model predictions � New global TEC maps will be produced continuously 1/8/2002 Alpbach Summer School 2002 / Team Nina 26

  14. Calculation of TEC error � Error values will be calculated for all conditions The specific error at any point will depend on � Density of nearby TEC measurements � Time history of TEC measurements � Model errors � Discrepancy between model values and TEC measurements � Well known error in TEC will provide the user with good reliability information 1/8/2002 Alpbach Summer School 2002 / Team Nina 27 Global TEC maps 1/8/2002 Alpbach Summer School 2002 / Team Nina 28

  15. Forecast Segment Gero Kleindienst, Sergey Apatenkov, Cathrine Fox, Maule Emilia Huttunen, Stefan Kiehas, Benjamin Luethi, Daniel Martini, Noora Partamies, Fabrice Portier-Fozzani, Aveek Sarkar, Carita Siponen 1/8/2002 Alpbach Summer School 2002 / Team Nina 29 Outline � NeQuick TEC model valid during quiet time � Regional warnings for the storm and substorm periods � Archive of the global coverage of the TEC measurements for analysis and future prediction 1/8/2002 Alpbach Summer School 2002 / Team Nina 30

  16. CME Warning System Flare Halo CME observation Level: X-ray flux (GOES-8/GOES-10) SOHO/LASCO Locations: SOHO/EIT Disappearing filament H α -images (ground solar observatories) Activity in “dangerous region“ CME speed and CME WARNING! estimate of arrival time to 1 AU ~1.5 – 4 days 1/8/2002 Alpbach Summer School 2002 / Team Nina 31 Future of CME Warning • Improved measurements by STEREO (2007) • Monitoring of type II radio bursts (tracking of CMEs to 1 AU) • Better observations of CME source region topology and realistic models operating in near-real-time 1/8/2002 Alpbach Summer School 2002 / Team Nina 32

  17. Warning Regions HL HL = high latitude region LL LL = low latitude region HL ☺ No Problems From the auroral � oval model by Be careful Feldstein [1963] � I‘m lost 1/8/2002 Alpbach Summer School 2002 / Team Nina 33 Isolated Substorms � ☺ HL : � for 18 – 02 MLT ( � for ±2 h) LL : Quiet time model ( ☺ ) � L1 (1h ahead) Substorm B, B x , B y , ε > 10 11 W and warning to HL B z , V B Z < 0 for at region for the measured least 20min next 2h θ 2 ε = 7 × 2 4 10 BV sin ( ) l 0 2 1/8/2002 Alpbach Summer School 2002 / Team Nina 34

  18. Storm Warning Dst STORM From L1 (1h ahead): dDst Dst = αε − τ dt R Burton et al., 1975 Main phase (~6h): HL: � for 16 – 08 MLT ( � for ± 2h) Storm limit: LL: � Dst < -50nT Severe Storm limit: Recovery Phase (~3h): Dst < -100nT HL: � → � everywhere LL : � 1/8/2002 Alpbach Summer School 2002 / Team Nina 35 Future � Auroral precipitation � Auroral oval location (AE/AL, NOAA, DMSP) � Neutral wind � Transportation of the plasma from high to mid latitudes � Ring current decay � F region bubbles (quiet time equatorial regions) Better understanding of the Sun‘s activity, magnetospheric and ionospheric dynamics and their coupling to the solar wind to get more accurate models and more reliable and longer term predictions 1/8/2002 Alpbach Summer School 2002 / Team Nina 36

Recommend

More recommend