1. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 1 H. Fagard (IGN) THE DORIS NETWORK: STATUS REPORT ON RENOVATION AND COLLOCATIONS Hervé FAGARD (Institut Géographique National)

2. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 2 H. Fagard (IGN) The network on 2003/01/01 56 stations, 33 countriesCircles: SPOT-n & Envisat, 12°

3. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 3 H. Fagard (IGN) Distribution of the DORIS equipment Version 1.0 or 1.1 beacon Alcatel antenna Starec antenna Version 2 beacon + + 9 stations Version 3 beacon 24 stations Alcatel antenna Starec antenna + + 1 station9 stations Alcatel antenna Starec antenna + + 1 station12 stations

4. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 4 H. Fagard (IGN) SPOT-2 TOPEX SPOT-3 Evolution of the network SPOT-4 JASON ENVISAT SPOT-5

5. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 5 H. Fagard (IGN) Network: latest news Two new stations installed at the end of 2002: –Thule (Greenland) –Sal (Cape Verde), replacing Dakar Theoretical orbit coverage (when all stations are operating): –“Low” satellites (SPOT-2, 4, 5 & Envisat) : 88 % –“High” satellites (Topex & Jason): 98 % Stations renovated in 2002: –Tristan da Cunha, Terre Adélie, Port Moresby, Kauai Next planned renovations: –Manila (next week) –St Helena, Ascension (March) Mount Stromlo destroyed by fire in January; should be rebuilt by mid-2003

6. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 6 H. Fagard (IGN) Network renovation progress

7. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 7 H. Fagard (IGN) Antennas estimated stability (2002/01/01)

8. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 8 H. Fagard (IGN) Collocations with other IERS techniques: theoretical vs. actual Many collocated instruments are not currently operating: –Discontinued long-term occupation by: »VLBI (Richmond, Santiago) »SLR (e.g. Dionysos, Easter Island, Goldstone, etc.) –Short duration (2 days only once, to a few days per year) mobile VLBI occupation (Toulouse, Ponta Delgada, Metsähovi, Greenbelt) Unreliable tie: –Insufficient accuracy, measured only once, sometimes many years ago –Very long baseline, different geological movements (e.g. Kourou) Network future evolutions should aim at adding a few VLBI and SLR collocations

9. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 9 H. Fagard (IGN) Theoretical/actual number of collocations DORIS collocation with: theoreticalactual SLR only10 GPS only1721 VLBI+GPS (no SLR)75 SLR+GPS (no VLBI)56 VLBI+SLR+GPS61

10. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 10 H. Fagard (IGN) Theoretical collocations with other IERS techniques

11. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 11 H. Fagard (IGN) Actual collocations with other IERS techniques

12. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 12 H. Fagard (IGN) DORIS-DORIS collocations (1) 29 DORIS stations have multiple antenna positions: –Two different antenna positions at 21 sites –Three different antenna positions at 8 sites All ties between different antenna positions on the same site have been measured accurately, except: –AMSA-AMSB (approximate connection planned, AMSA no longer exists) –HBKA-HBLA (antenna moved by host agency, no direct survey) –HELA-HELB (antenna change by host agency, no survey) –KERA-KERB (dubious KERA antenna height) –GOLA-GOMA (no direct connection)

13. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 13 H. Fagard (IGN) DORIS-DORIS collocations (2)

14. IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 2003 14 H. Fagard (IGN) Tide gauges collocations (<10 km)