1. NGOS NORDIC GEODETIC OBSERVING SYSTEM NKG Task Force Markku Poutanen, Per Knudsen, Mikael Lilje, Hans-Peter Plag, Hans-Georg Scherneck

2. WHY NGOS Much has been done over the recent years to integrate geodetic observational infrastructure both on global and regional level into more homogeneous networks. The Nordic Geodetic Commission (NKG) has recognised the necessity for contributions to global geodetic networks as well as regional homogenisation and standardisation.

3. NGOS TASK FORCE NGOS Task Force was established in 2002 to write a paper that defines an integrated regional approach as a major in-situ infrastructure for geodetic observations required for a wide range of scientific and practical applications both in the Nordic region and on global level.

4. NGOS integrates fundamental geodetic techniques for the longterm observation of Earth system parameters. NGOS is a regional implementation and densification of the IGGOS (Integrated Global Geodetic Observing System). two main contributions of Geodesy to global monitoring, namely –(1) the maintenance of a highly accurate references frame as the backbone for all other observation systems, and –(2) observations of key variables of the Earth system, such as changes in its figure and gravity field, and variations in the Earth's rotation. For the Nordic countries, a main focus will by on crustal motion, dynamics of glaciated areas and sea level.

5. NGOS OBSERVATIONS NGOS is envisaged to provide the necessary observations to determine - geodetic positions and to infer the kinematics of the Earth surface, - gravity and its temporal changes, and - Earth rotation and its temporal changes.

6. THE DOCUMENT … is still under preparation but will... –describe the general frame for NGOS as a system contributing to global and regional Earth observations. –assesses the status quo situation of the regional geodetic observing systems –identifies deficiencies and gaps in the in-situ infrastructure. –provides advice for the implementation of necessary adaptations and potential new developments in network and information/data management task for the observing techniques involved.

7. CHAPTERS … not finally decided but at the moment… 1. Introduction 2. Applications of Geodetic Observations 3. State-of-the-art in geodetic observing techniques 4. Towards a Geodetic Observing System in the Nordic Area 5. The Nordic Geodetic Observing System 6. Current limitations and means to progress 7. Relations between NGOS and other on-going activities 8. Conclusion

9. Table 1. The NGOS network. Columns: j = approximate latitude; l = approximate longitude, h = ellipsoidal height; VLB = VLBI; SLR = SLR; GNS = GNSS (GPS + GLONASS); DO = DORIS, AG = Absolute gravimeter, SCG = Superconducting gravimeter; TG = Tide gauge; CN = Control network, FP = Footprint; ITR = ITRF point; IVS = IVS point; IGS = IGS point; ILR = ILRS point; ECG = ECGN point; EPN = EPN point; GGP = GGP point; ESE = ESEAS point Symbols: P = proposed; M = monument available; E = episodic measurements; R = repeated measurements; C = continuous measurements; : = none