Papers by Matti Ollikainen
Evaluation of Geoid Models with GPS/Levelling Points in Sweden and Finland
First CHAMP Mission Results for Gravity, Magnetic and Atmospheric Studies, 2003
Five different geoid models are analysed to estimate the possible error budget of new global geoi... more Five different geoid models are analysed to estimate the possible error budget of new global geoids based on the data from the gravity satellites CHAMP, GRACE and GOCE. We used the global models OSU91A and EGM96, the European model EGG97, the Nordic model NKG96 and the newest model for Finland FIN2000. FIN2000 is fitted to the Finnish height system and is the most accurate of the five. A total of 245 points in Finland and Sweden was used in the analysis. For all points, GPS-determined heights were avail-able as well as orthometric or normal heights based on spirit levelling. From these heights the geoid height was calculated and compared with corresponding geoid heights obtained from the geoid models, allowing us to estimate the geoid model error and its spatial variation.
Suomen Geoidimallit Ja Niiden Käyttäminen Korkeuden Muunnoksissa
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For use within a computer-based digital control System, a Morristown, NJ (US) calling mechanism a... more For use within a computer-based digital control System, a Morristown, NJ (US) calling mechanism and method for allowing both dynamic (*) Notice: Subject t disclai the t f thi linked application objects and Static linked application OCC. I se "N. s Wier objects created with heterogeneous development tool Sets to S.C. 154(b) by 0 interact with a kernel of the system or with each other. In one a-embodiment, the calling mechanism includes: (1) a dynamic link interface that employs only Standards-based Software (21) Appl. No.: 08/994,415 calls to allow the dynamic linked application objects to (22) Filed: Dec. 19, 1997 interact with the kernel, (2) a Static link interface that
National report of Finland
The FIN2000 geoid (or height reference surface) is an adjusted version of the Nordic geoid NKG96 ... more The FIN2000 geoid (or height reference surface) is an adjusted version of the Nordic geoid NKG96 in Finland. Its epoch is 2000.0 and it refers to orthometric heights in the N60 height system. It is based on 193 GPS/levelling points; 25 percent of them are points of precision ...
GPS operations at Olkiluoto. Kivetty and Romuvaara for 1998
WEGENER 2000 Present-day 3-D deformation of Fennoscandia : Analysis and interpretation of the BIFROST GPS observations
We present results of 2477 days of continuous GPS observations and daily geodetic solutions in th... more We present results of 2477 days of continuous GPS observations and daily geodetic solutions in the BIFROST networks. We analyse the position solutions in terms of regional motions induced by a variety of geophysical phenomena operating over a range of time scales. The primary purpose is to resolve constant rates of deformation produced by the on-going glacial isostatic adjustment of the region following the deglaciation of the Fennoscandian ice sheet. Power spectrum analysis of the residuals indicate that we are able to determine constant rates of horizontal motion with a precision below 0.1 mm/yr (vertical below 0.2 mm/yr). The observed eld of motion is strongly correlated to that predicted by postglacial rebound models. However, a number of discrepancies exist that are currently open to interpretation. These discrepancies may result from shortcomings of the adopted rebound model, such as uncertainties in the deglaciation model or the absence of lateral heterogeneity and/or anisotr...
Use of the Finnish Permanent GPS Network (Finnnet) in Regional GPS Campaigns
International Association of Geodesy Symposia, 1998
We give an overview of time series analyses of permanent GPS stations using solutions of the IGS ... more We give an overview of time series analyses of permanent GPS stations using solutions of the IGS and FinnRef® networks. Lomb periodograms show in most cases a statistically significant annual period both in station coordinates and inter-station distances. In regional networks the scale of the whole network changes periodically, and in some cases there is also a secular trend. There are several possible causes of scale variations, which may not be separable in the data. These include computational artefacts, periodic systematic errors in satellite orbits, signal path delay variations, and geophysical causes like loading and postglacial rebound. We discuss possible reasons, their significance, and their consequences on high-precision GPS observations. Additional constraints, e.g. time series from the superconducting gravimeter, are also discussed.
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Papers by Matti Ollikainen