IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20031 H. Fagard (IGN)

THE DORIS NETWORK: STATUS REPORT ON RENOVATION AND COLLOCATIONS

Hervé FAGARD (Institut Géographique National)

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20032 H. Fagard (IGN)

The network on 2003/01/01

• 56 stations, 33 countries • Circles: SPOT-n & Envisat, 12°

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20033 H. Fagard (IGN)

Distribution of the DORIS equipment

Version 1.0 or 1.1 beacon

Alcatel antennaStarec

antenna

Version 2 beacon

+

+

9 stations

Version 3 beacon

24 stations

Alcatel antennaStarec

antenna

+

+

1 station 9 stations

Alcatel antennaStarec

antenna

+

+

1 station 12 stations

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20034 H. Fagard (IGN)

0

10

20

30

40

50

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

Number of stations (end of the year) Renovations

SPOT-2TOPEX

SPOT-3

Evolution of the network

SPOT-4JASON

ENVISATSPOT-5

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20035 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

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20036 H. Fagard (IGN)

Network renovation progress

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20037 H. Fagard (IGN)

Antennas estimated stability (2002/01/01)

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20038 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

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 20039 H. Fagard (IGN)

Theoretical/actual number of collocations

DORIS collocation with: 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

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 200310 H. Fagard (IGN)

Theoretical collocations with other IERS techniques

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 200311 H. Fagard (IGN)

Actual collocations with other IERS techniques

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 200312 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)

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 200313 H. Fagard (IGN)

DORIS-DORIS collocations (2)

IDS Workshop - ENSG Marne-la-Vallée - February 20-21, 200314 H. Fagard (IGN)

Tide gauges collocations (<10 km)