THE DORIS NETWORK STATUS REPORT ON RENOVATION AND

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

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

Distribution of the DORIS equipment Version 1. 0 or 1. 1 beacon Version 2 beacon + + Alcatel antenna 3 H. Fagard (IGN) 24 stations + + Alcatel antenna Starec antenna 9 stations Version 3 beacon Alcatel antenna Starec antenna 1 station 12 stations Starec antenna 1 station 9 stations IDS Workshop - ENSG Marne-la-Vallée - February 20 -21, 2003

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

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 5 H. Fagard (IGN) IDS Workshop - ENSG Marne-la-Vallée - February 20 -21, 2003

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

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

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 8 H. Fagard (IGN) IDS Workshop - ENSG Marne-la-Vallée - February 20 -21, 2003

Theoretical/actual number of collocations DORIS collocation with: 9 theoretical actual SLR only 1 0 GPS only 17 21 VLBI+GPS (no SLR) 7 5 SLR+GPS (no VLBI) 5 6 VLBI+SLR+GPS 6 1 H. Fagard (IGN) IDS Workshop - ENSG Marne-la-Vallée - February 20 -21, 2003

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

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

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) 12 H. Fagard (IGN) IDS Workshop - ENSG Marne-la-Vallée - February 20 -21, 2003

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

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