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  • 1
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    Reappraisal of the Angerman River decay time estimate and its application to determine uncertainty in Earth viscosity structure (2015)
    Oxford University Press
    Details
    Publication Date: 2015-03-15
    Description: Relative sea level histories from previously glaciated areas have been used to study Earth rheology and ice sheet evolution during the last glacial cycle. The analysis of postglacial decay times has been used to place estimates on Earth viscosity structure that are relatively independent of uncertainty in the local ice history. Reconstructed sea levels from Ångermanland, Sweden have been commonly adopted for this purpose. We have assessed and compiled an updated relative sea level curve for this region, combining both varve-dated and radiocarbon dated index points. We fitted an exponential curve to the observations, taking into account estimates of eustatic sea level rise, elevation uncertainties as well as the geographical spread of the data sites to arrive at a decay time range (2 ) of 4.2–4.9 kyr for the whole record length (0–8 kyr) and 4.2–6.2 when 0–7 kyr fits are included. We computed model decay times using a large suite of over 900 ice and earth model combinations based on over 400 three-layer Earth viscosity models and more than 30 ice history reconstructions. Based on these extensive results, we confirm that decay time estimates are relatively independent of the regional ice model (at least within the range of ice chronology uncertainties) and so this data parametrization provides a relatively robust measure of Earth viscosity structure. We find that the observational constraints listed above are satisfied by 29 (8 kyr record) and 52 (7 and 8 kyr record) of the viscosity models considered. These subsets define uncertainty ranges in upper and lower mantle viscosity that are interdependent (Fig. 5). Consistent with previous analyses, we find that the observational decay time estimate does not provide useful constraints on model lithospheric thickness (within the range explored; 46–146 km).
    Keywords: Geodynamics and Tectonics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 2
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    Consistent height transformations between geodetic and meteorologic reference systems (2012)
    In:  AGU 2012 Fall Meeting (San Francisco, USA 2012)
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/conferenceObject
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  • 3
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    Improving GRACE mass estimates for the Baltic Sea and validation using in situ measurements. (2008)
    In:  Eos, Transactions, American Geophysical Union, Suppl.; 89, 53
    Details
    Publication Date: 2020-02-12
    Description: The variation in the sea level of the semi-closed Baltic Sea has been monitored in several complimentary ways. Now GRACE provides a method to directly measure the total mass variability in the Baltic. Using in situ and modelled Baltic data, we show that GRACE is able to recover the variation in the total water mass. We derive sea level surfaces from tide gauge data and estimate steric effects using hydrodynamic models as well as in situ salinity and temperature measurements for their verification. With its areal extent (~400 km x 1000 km) as well as fast temporal variations (hourly to monthly), the Baltic Sea provides a challenging test field for the temporal and spatial resolution of GRACE. We use both the standard monthly GRACE gravity field solutions and regional solutions and compare their capability to recover Baltic water mass variations. Due to spatial averaging, the GRACE mass estimates over the elongated area are contaminated by signals outside the region. The contribution of continental hydrology can be removed using water storage models to estimate mass variations on surrounding land areas. We discuss the processing steps required for the different GRACE solutions to improve the GRACE mass estimates for the Baltic, including mitigation of signal leakage as a result of spatial filtering. The capability of GRACE to recover internal mass redistributions in the Baltic is also investigated. Finally, we discuss the reduction of the Baltic contribution for studying land-uplift signal due to post-glacial rebound.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/conferenceObject
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  • 4
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    Baltic sea mass variations from GRACE: comparison with In Situ and modelled sea level heights (2010)
    In:  Gravity, Geoid and Earth Observation : IAG Commission 2: Gravity Field, Chania, Crete, Greece, 23-27 June 2008 | International Association of Geodesy Symposia ; 135
    Details
    Publication Date: 2020-02-12
    Description: The monthly variation in the water mass of the semi-enclosed Baltic Sea is about 60 Gt RMS over an area of 390000km2 . The Baltic has a dense network of tide gauges (TGs), and several high-resolution regional hydrodynamic models, making it one of the best-monitored seas for mass variations of this size in the world. We investigate the performance of different GRACE gravity field solutions to recover this oceanic mass variation using in situ measurements of sea-level heights. For GRACE, we use both the standard monthly solutions as well as regional solutions to estimate the total water storage in the Baltic Sea. For the “ground truth”, we use sea-level measurements in the network of tide gauges around the Baltic Sea. For comparison, we have access to data from two hydrodynamic models. The water mass estimated from the constructed sea surfaces is then compared with different GRACE estimates. At present, we ignore the steric anomalies, as they are small in the Baltic Sea. We also discuss the “leakage” between land hydrology and the Baltic Sea in the GRACE estimates of water storage.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/bookPart
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  • 5
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    GRACE Water Storage Estimates in Finland and the Effect of Baltic Sea Level Variation. (2007)
    In:  Eos Transactions, American Geophysical Union, Suppl., Vol. 88(52), U21C-0621 (Poster)
    Details
    Publication Date: 2020-02-12
    Description: We compare the GRACE water storage estimates in Finland with the total water storage from a high-accuracy local hydrological model. Being a significant source of mass variations, we also discuss the leakage of the Baltic mass into estimates of continental water storage in GRACE solutions. For the total water storage, we use the model of the Watershed Simulation and Forecasting System (WSFS) of the Finnish Environment Institute. WSFS covers the whole hydrological cycle, including surface and subsurface water and snow. For GRACE water storage, we use three estimates obtained through different processing methods. First, we use the standard monthly GRACE gravity field solutions and apply appropriate filtering. To improve the spatial and temporal resolution, two regional solutions are studied. NASA has recently made available GRACE estimates of 10-days mass change in 4x4 degree blocks (mascons) over the worlds' continents covering the period April 2003 to April 2006. In addition to the mascon solutions, we will also use the regional solutions employing GRACE KBR data derived from in situ disturbance potential measurements via the energy conservation method. The monthly variation in the water mass of the semi-enclosed Baltic sea is about 60 Gt RMS. It is governed by the water exchange with the North sea through the Danish straits, and is difficult to catch in the global ocean circulation models. We study the contribution of Baltic mass variation to the GRACE estimates of water storage. On the other hand, the Baltic has both a dense network of tide gauges and several specific high-resolution hydrodynamical models, making it possibly the best-controlled mass variation of this size in the world. We discuss the possibilities of using Baltic mass to validate and compare GRACE solution methods.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/conferenceObject
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  • 6
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    Coastal meadows and sea level rise in the northern Gulf of Finland: possibilities for adaptation (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-04
    Description: Coastal meadows are an ecologically important habitat type and provide suitable conditions for a wide variety of species, many of which are specialized to live in this environment. In addition, many bird species are dependent on coastal meadows as nesting and feeding areas. Coastal meadows remain open and treeless either because of grazing or naturally due to the effect of waves, sea level variations, and sea ice.Because of their location on low-lying ground at the immediate vicinity of the seashore, coastal meadows are particularly vulnerable to sea level rise. We investigate this vulnerability and potential adaptation on the northern (Finnish) coast of the Gulf of Finland. The rate of land uplift is 3-4 mm/a in the area, which approximately equals the current rate of sea level rise. However, by 2100 mean sea level in the region is projected to rise by 15, 30 or 60 cm depending on the emission scenario (SSP1-2.6, SSP2-4.5, or SSP5-8.5, respectively). Even a higher rise is possible.Due to the relatively steep topography, the coastal zone in the area is rather narrow and coastal meadows are predominantly small. When the sea level rises, the meadows can adapt by moving inland, if there is suitable low-lying open space and the spreading is not prevented by roads, other infrastructure, or rocky terrain. In this analysis, we utilize geospatial data of habitat types and land use, a digital elevation model, and projections of mean sea level rise to investigate the adaptation potential of coastal meadows.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 7
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    Exploring non-tidal loading deformation correction in GNSS time series analysis using GAMIT/GLOBK (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-06-19
    Description: The masses in the Earth’s atmosphere and surface cause the crust to deform. Part of these mass movements are periodic, e.g. tides in the oceans and in the atmosphere, but there are also non-periodic movements. Periodic (tidal) phenomena are quite well understood and modelled, whereas the non-periodic (non-tidal) phenomena are harder to model due to non-repeating patterns in the mass changes. Understanding the tidal and non-tidal loading improves the quality of the geodetic time series and thus, improves the stability of the reference frames. The tidal corrections to geodetic time series are done routinely, following recommendations and guidelines of the IERS Conventions. We investigated the 3D deformations in Fennoscandia induced by non-tidal atmospheric loading (NTAL) through GNSS time series modeling using GAMIT/GLOBK software. We have used 5 months of data from continuous GNSS stations belonging to FinnRef (Finnish Permanent GNSS Network) and EPN (EUREF Permanent GNSS Network) from year 2015. Two coordinate time series solutions were generated: first (reference) solution was estimated without applying loading model, while for the second solution a gridded loading model was used. We also downloaded loading correction time series from an openly available server and created the third time series by subtracting the loading correction from the reference time series. We compared the variance of three time series to see which method produces the most stable time series. The effect of NTAL correction is quite small, but not insignificant and the implementation trough the software is the most straightforward way of doing it.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 8
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    Evaluating the 3D deformation induced by non-tidal loading in GNSS time series in Finland (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-08-09
    Description: The Earth’s surface is continuously deforming at various temporal and spatial scales. The deformation is caused by the changing mass distribution of atmospheric, oceanic, hydrological masses, glaciers and ice sheets as well as earthquakes and/or human activities. Some of the mass changes are periodic and rather well known (e.g., ocean and solid Earth tides), whereas the non-periodic mass changes are not that well known or easy to model. The latter part is often referred to as non-tidal loading (NTL) and is the focus of the study. A deeper understanding of the NTL in geodetic time series, particularly in regional and/or local scales, will result in insights in modelling and removing the effect from the time series, thus improving the stability of the geodetic time series. Examining the impacts of different loading products in our region is critical for accurately removing the loading signal. Currently, there are several open sources for loading products. In this study, we compared the performance of these loading products and investigated their impact on the scatter of GNSS time series in the permanent GNSS stations in Finland (FinnRef). We studied five different hydrological loading models, six different non-tidal atmospheric loading models, and three different non-tidal oceanic loading models to see how various loading configurations operate and how they affect the noise characteristics of GNSS 3D time series, and ultimately figure out which models is most realistic in Finland.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 9
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    Skills needed in work life: case study of Geoinformatics Master’s program (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-03
    Description: What are the skills that we are teaching in our Master’s program in Geoinformatics? How useful those skills are for the new graduates and which skills do they end up using in their working life? What are the skills that the companies that are hiring the new graduates are looking for? As part of renewing our Master’s program we asked our alumni which skills they have found useful in the working life. We also asked a group of our stakeholders to evaluate the same skills for the people they might be hiring. We had a set of predefined skills, both general and field-specific, that we asked the answerers to rate based on their usefulness in the working life. There was also option for commenting the skill set and adding something that was missing. The results show that both groups find the problem-solving skills the most important general skill. For the alumni the other two skills in top three were project management and team-work skills, whereas the people who might be hiring the graduates ranked programming and writing skills above them. From the field-specific skills understanding and implementing theories was the ranked as the most important. Other skills, such as data analysis or management of measuring process, were ranked in varying places depending on the duties of the person answering. Based on the results we are going to critically evaluate our course contents and add components of problem solving and team working where possible.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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