| 1. |
- Poutanen, Markku, et al.
(författare)
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The Nordic Geodetic Observing System (NGOS)
- 2007
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Ingår i: International Association of Geodesy Symposia, Dynamic Planet. ; , s. 749-756
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The Nordic Geodetic Observing System (NGOS) integrates fundamental geodetic techniques for the long-term observation of Earth system parameters. The Nordic Geodetic Commission (NKG) established a Task Force with the mission to prepare a document providing the definition and draft for the implementation of the NGOS.The regional system aligns with international efforts such as the Global Earth Observation System of Systems (GEOSS) and Global Observing Systems and adheres to the Integrated Global Observing Strategy (IGOS). Recent developments in the structure and function of the International Association of Geodesy cumulated in the establishment of the Global Geodetic Observing System, GGOS. NGOS is planned as a regional implementation and densification of the GGOS.The NGOS is proposed as a system that will serve a wide range of scientific and practical applications. For the Nordic countries, a main focus will be on crustal motion, dynamics of glaciated areas and sea level. NGOS aims to provide geodetic observations for the Nordic area that are of sufficient quantity and quality to serve most of the needs of global Earth observation as well as practical and scientific applications in the region. In particular, NGOS will contribute to the GGOS and other IAG Services; European activities such as EUREF, ECGN, EUVN, and ESEAS; provide the reference frames for the Nordic countries, as well as contribute to the global ones; support scientific projects related to the geodynamics of the Nordic area and provide ground-truth for satellite missions. In this paper we describe the plans and current status of the NGOS.
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| 2. |
- Bergstrand, Sten, 1971, et al.
(författare)
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BIFROST: Noise properties of GPS time series
- 2007
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Ingår i: in "Dynamic Planet: Monitoring and Understanding a Dynamic Planet with Geodetic and Oceanographic Tools", IAG Symposium, Cairns, Australia, 22-26 August, 2005, Series: International Association of Geodesy Symposia , Vol. 130, Tregoning, Paul; Rizos, Chris (Eds.), Springer. - 9783540493495 ; 130, s. 123-130
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Konferensbidrag (refereegranskat)
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| 3. |
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| 4. |
- Bock, Dagmar, et al.
(författare)
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Atmospheric pressure loading displacement of SLR stations
- 2005
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Ingår i: Journal of Geodynamics. - : Elsevier BV. - 0264-3707. ; 39:3, s. 247-266
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the local displacement at ground stations of the world-wide Satellite Laser Ranging (SLR) network induced by atmospheric pressure variations. Since currently available modelling options do not satisfy the requirements for the target application (real-time availability, complete coverage of SLR network), a new representation is developed. In a first step, the 3-dimensional displacements are computed from a 6-hourly grid of 1°×1° global pressure data obtained from the ECMWF, for the period 19972002. After having been converted into pressure anomalies, this pressure grid is propagated into horizontal and vertical station displacements using Greens functions and integrating contributions covering the entire globe; oceans are assumed to follow the inverted barometer (IB) approximation. In the next step, a linear regression model is developed for each station that approximates the time-series of the predicted vertical displacements as well as possible; this regression model relates the vertical displacement of a particular station to the local (and instantaneous) pressure anomaly. It is shown that such a simple model may represent the actual vertical displacements with an accuracy of better than 1 mm; horizontal displacements are shown to be negligible. Finally, the regression model is tested on actual SLR data on the satellites LAGEOS-1 and LAGEOS-2, covering the period January 2002 until April 2003 (inclusive). Also, two model elements are shown to be potential risk factors: the global pressure field representation (for the convolution method) and the local reference pressure (for the regression method). The inclusion of the atmospheric pressure displacement model gives improvements on most of the elements of the computations, although the effects are smaller than expected since the nominal effect is absorbed by solved-for satellite parameters.
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| 5. |
- Bos, Machiel, 1960, et al.
(författare)
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Computations of Green's Functions for Ocean Tide Loading
- 2012
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Ingår i: Sciences of Geodesy-II. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 1-52, s. 1-52
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The Earth deforms periodically due to the varying weight of the ocean tides. Classical terrestrial geodetic techniques such as gravimetry, strain and tilt observe this deformation clearly. Also space geodetic techniques have reached an accuracy level where this loading signal can no longer be ignored. We present here the basic physical assumptions that underlie, and the derivation of, the mathematical framework that is used nowadays to compute these deformations. Special attention has been paid to the definition of the boundary conditions, how to treat the fluid core and the peculiarities that surround the deformation of the solid Earth at degree one. Also a short explanation of the Longman-Paradox is given. Finally, we discuss numerical methods to solve the differential equations and how to form the Green's functions that describe the ocean tide loading due to a point load.
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| 6. |
- Elgered, Gunnar, 1955, et al.
(författare)
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GNSS for global environmental Earth observation
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This booklet is produced within the Gfg2 project, a three year coordination action, funded by the 7th Framework Program of the European Commission under the Environment theme. Its mission is to better assess the value of Global Navigational Satellite Systems (GNSS) for Global Environmental Earth Observation (GEEO) and GEOSS.
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| 7. |
- Elgered, Gunnar, 1955, et al.
(författare)
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GNSS för globala jordobservationer
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Detta häfte har producerats av Gfg2-projektet, en treårig koordineringsaktivitet finansierad av Europeiska kommissionens sjunde ramprogram inom dess miljötema. Projektets uppgift är att belysa värdet av jordobservationer med hjälp av globala navigationssystem (GNSS = Global Navigational Satellite Systems) för Global Environmental Earth Observation (GEEO) och Global Earth Observation System of Systems (GEOSS).
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| 8. |
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| 9. |
- Freier, Christian, et al.
(författare)
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Mobile quantum gravity sensor with unprecedented stability
- 2016
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 723:1, s. Art. no. 012050-
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Konferensbidrag (refereegranskat)abstract
- Changes of surface gravity on Earth are of great interest in geodesy, earth sciencesand natural resource exploration. They are indicative of Earth system's mass redistributions andvertical surface motion, and are usually measured with falling corner-cube- and superconductinggravimeters (FCCG and SCG). Here we report on absolute gravity measurements with amobile quantum gravimeter based on atom interferometry. The measurements were conductedin Germany and Sweden over periods of several days with simultaneous SCG and FCCGcomparisons. They show the best-reported performance of mobile atomic gravimeters todate with an accuracy of 39 nm/s^2, long-term stability of 0,5 nm/s^2 and short-term noise of 96 nm/s^2/(Hz)^1/2. These measurements highlight the unique properties of atomic sensors. Theachieved level of performance in a transportable instrument enables new applications in geodesyand related Fields, such as continuous absolute gravity monitoring with a single instrument underrough environmental conditions.
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| 10. |
- Haas, Rüdiger, 1966, et al.
(författare)
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Contributions of Onsala Space Observatory to GGOS
- 2015
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Ingår i: Proceedings of the 22nd European VLBI Group for Geodesy and Astrometry Working Meeting. - 9789892061917 ; , s. 125-129
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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