Reference frame densifications for Nordic and Baltic countries - From local analysis to common and consistent GNSS solutions

Sonja Lahtinen

Reference frame densifications for Nordic and Baltic countries - From local analysis to common and consistent GNSS solutions

Julkaisun otsikon käännös: Vertauskehysten tihennyksiä Pohjoismaiden ja Baltian alueelle

Sonja Lahtinen

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Terrestriset eli Maahan sidotut vertauskehykset on välttämättömiä, mutta usein huomaamattomia, nykyajan yhteiskunnille. Nykyään alueelliset terrestriset vertauskehykset luodaan ja ylläpidetään hyödyntäen jatkuvasti havaitsevia satelliittipaikannus- eli GNSS-mittausasemia. Fennoskandiassa jääkauden jälkeinen maankuoren palautuminen aiheuttaa deformaatiota, joka heikentää kansallisten Euroopan laajuiseen ETRS89-järjestelmään kiinnitettyjen staattisten vertauskehysten tarkkuutta. Deformaation huomioiminen on välttämätöntä, jotta voidaan muuntaa tarkasti koordinaatteja globaalista vertauskehyksestä kansallisiin ETRS89-vertauskehyksiin, kuten EUREF-FINiin Suomessa. Tässä väitöstutkimuksessa keskityttiin määrittämään globaalin vertauskehyksen tihennyksiä Pohjoismaiden ja Baltian alueelle. Työ tehtiin Pohjoismaisen geodeettisen komission (Nordic Geodetic Commission, NKG) GNSS-laskentakeskusprojektissa. Se pohjautuu kahdeksaan kunkin maan laskentakeskukseen, jotka laskevat oman alueensa osaverkon. Väitöstutkimuksen pääpaino oli kehittää metodeita osaverkkojen ratkaisuiden yhdistämiseen, koordinaattiaikasarjojen analyysiin ja pitkänajan koordinaatti- ja nopeusratkaisun määrittämiseksi mukaan lukien asemanopeuksien epävarmuudet. Tulokset osoittivat, että osaverkot olivat yhtenevät 1–2 mm tasolla yhdistetyn ratkaisun suhteen. Laskennan jakaminen osaverkkoihin vahvisti siten päiväratkaisuiden verkon runkoa, kun osa asemista laskettiin usean laskentakeskuksen toimesta. Asemien koordinaattiaikasarjojen epäjatkuvuksia analysoitiin sekä manuaalisesti sekä kehitetyllä automaattisella metodilla, jolla pystyttiin havaitsemaan 74 % epäjatkuvuuksista suhteessa manuaaliseen tulkintaan. Päiväratkaisuista laskettiin asemanopeudet noin 270 asemalle, joiden aikasarjojen pituudet vaihtelivat 3 ja 20 vuoden välillä. Yli 90 % asemista, joiden aikasarjat olivat vähintään kymmennen vuoden pituisia, nopeuksien epävarmuudet olivat enintään 0.10, 0.10 ja 0.25 mm/v pohjois-, itä-, ja pystysuuntiin vastaavasti. GNSS-aikasarjojen yksityiskohtainen ymmärtäminen Pohjoismaiden ja Baltian alueella tulee lisäämään eurooppalaisten ja globaalinen vertauskehysten laatua, koska osan asemien data käytetetään kansainvälisissä ratkaisuissa. Määritetettyjä globaalin vertauskehyksen tihennyksiä tullaan hyödyntämään kansallisten geodeettisten vertauskehysten ylläpidossa sisältäen deformaatiomallinuksen ja tarkkojen koordinaattimuunnosten kehityksen. Näiden avulla pystytään pidentämään kansallisten vertauskehysten, kuten EUREF-FINin, käyttöaikaa.

Julkaisun otsikon käännös	Vertauskehysten tihennyksiä Pohjoismaiden ja Baltian alueelle
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Nordman, Maaria, Vastuuprofessori Koivula, Hannu, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-0770-8, 978-951-48-0280-5
Sähköinen ISBN	978-952-64-0771-5, 978-951-48-0279-9
Tila	Julkaistu - 2022
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

satelliittipaikannus
terrestriset vertauskehykset
GNSS-aikasarjat
GNSS-nopeudet

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-64-0771-5

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@phdthesis{b61d162b0f624e86b137a6eed1e464ef,

title = "Reference frame densifications for Nordic and Baltic countries - From local analysis to common and consistent GNSS solutions",

abstract = "Terrestrial, Earth-fixed, reference frames are fundamental, but often unnoticeable, components for modern societies. Today, regional terrestrial reference frames are created and maintained by the measurement of continuously operating Global Navigation Satellite System (GNSS) reference stations. In Fennoscandia, glacial isostatic adjustment (GIA) causes deformation, also known as postglacial rebound, decreasing the accuracy of national static reference frames referring to the European Terrestrial Reference System 1989 (ETRS89). Considering the deformation is thus a necessity to accurately transform coordinates from the International Terrestrial Reference Frame (ITRF) to national ETRS89 realisations such as EUREF-FIN in Finland. This dissertation focused on estimating densified reference frame realisations in the global reference frames for the Nordic and Baltic countries. The work was carried out in the GNSS Analysis Centre project of the Nordic Geodetic Commission (NKG). It builds on eight local analysis centres, one in each country, processing its sub-net. The emphasis of the dissertation was on developing methods for combination of the sub-nets, analysis of the time series, and estimating a multi-year position and velocity solution, including uncertainties of the station velocities. The results showed that the sub-net solutions were consistent with the combined solution within 1–2 mm. The distribution of the GNSS processing into local sub-nets thus strengthened the daily solutions due to the redundantly processed reference stations. The station-wise position time series were analysed for offsets both manually and with the developed automatic approach with a 74 % success rate in respect to the manual interpretation. Station velocities were estimated for approximately 270 stations from daily position solutions. The lengths of time series varied between 3 and 20 years. Uncertainty levels of 0.10, 0.10, and 0.25 mm/y for the north, east, and up components respectively were reached with 10 years of data for more than 90 % of stations. The detailed understanding of the GNSS time series in the Nordic and Baltic countries will enhance the quality of the European and global terrestrial reference frame realisations, because some of the stations contribute with the same data to those solutions. The densified reference frame solutions will be utilised in the maintenance of the national geodetic reference frames, including deformation modelling and the development of the accurate coordinate transformations. This will ultimately extend the lifetime of the national reference frames like EUREF-FIN.",

keywords = "GNSS, terrestrial reference frames, GNSS time series, GNSS velocities, ITRF, satelliittipaikannus, terrestriset vertauskehykset, GNSS-aikasarjat, GNSS-nopeudet, GNSS, terrestrial reference frames, GNSS time series, GNSS velocities, ITRF",

author = "Sonja Lahtinen",

year = "2022",

language = "English",

isbn = "978-952-64-0770-8",

series = "Aalto University publication series DOCTORAL THESES",

publisher = "Aalto University",

number = "54",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Reference frame densifications for Nordic and Baltic countries - From local analysis to common and consistent GNSS solutions

AU - Lahtinen, Sonja

PY - 2022

Y1 - 2022

N2 - Terrestrial, Earth-fixed, reference frames are fundamental, but often unnoticeable, components for modern societies. Today, regional terrestrial reference frames are created and maintained by the measurement of continuously operating Global Navigation Satellite System (GNSS) reference stations. In Fennoscandia, glacial isostatic adjustment (GIA) causes deformation, also known as postglacial rebound, decreasing the accuracy of national static reference frames referring to the European Terrestrial Reference System 1989 (ETRS89). Considering the deformation is thus a necessity to accurately transform coordinates from the International Terrestrial Reference Frame (ITRF) to national ETRS89 realisations such as EUREF-FIN in Finland. This dissertation focused on estimating densified reference frame realisations in the global reference frames for the Nordic and Baltic countries. The work was carried out in the GNSS Analysis Centre project of the Nordic Geodetic Commission (NKG). It builds on eight local analysis centres, one in each country, processing its sub-net. The emphasis of the dissertation was on developing methods for combination of the sub-nets, analysis of the time series, and estimating a multi-year position and velocity solution, including uncertainties of the station velocities. The results showed that the sub-net solutions were consistent with the combined solution within 1–2 mm. The distribution of the GNSS processing into local sub-nets thus strengthened the daily solutions due to the redundantly processed reference stations. The station-wise position time series were analysed for offsets both manually and with the developed automatic approach with a 74 % success rate in respect to the manual interpretation. Station velocities were estimated for approximately 270 stations from daily position solutions. The lengths of time series varied between 3 and 20 years. Uncertainty levels of 0.10, 0.10, and 0.25 mm/y for the north, east, and up components respectively were reached with 10 years of data for more than 90 % of stations. The detailed understanding of the GNSS time series in the Nordic and Baltic countries will enhance the quality of the European and global terrestrial reference frame realisations, because some of the stations contribute with the same data to those solutions. The densified reference frame solutions will be utilised in the maintenance of the national geodetic reference frames, including deformation modelling and the development of the accurate coordinate transformations. This will ultimately extend the lifetime of the national reference frames like EUREF-FIN.

AB - Terrestrial, Earth-fixed, reference frames are fundamental, but often unnoticeable, components for modern societies. Today, regional terrestrial reference frames are created and maintained by the measurement of continuously operating Global Navigation Satellite System (GNSS) reference stations. In Fennoscandia, glacial isostatic adjustment (GIA) causes deformation, also known as postglacial rebound, decreasing the accuracy of national static reference frames referring to the European Terrestrial Reference System 1989 (ETRS89). Considering the deformation is thus a necessity to accurately transform coordinates from the International Terrestrial Reference Frame (ITRF) to national ETRS89 realisations such as EUREF-FIN in Finland. This dissertation focused on estimating densified reference frame realisations in the global reference frames for the Nordic and Baltic countries. The work was carried out in the GNSS Analysis Centre project of the Nordic Geodetic Commission (NKG). It builds on eight local analysis centres, one in each country, processing its sub-net. The emphasis of the dissertation was on developing methods for combination of the sub-nets, analysis of the time series, and estimating a multi-year position and velocity solution, including uncertainties of the station velocities. The results showed that the sub-net solutions were consistent with the combined solution within 1–2 mm. The distribution of the GNSS processing into local sub-nets thus strengthened the daily solutions due to the redundantly processed reference stations. The station-wise position time series were analysed for offsets both manually and with the developed automatic approach with a 74 % success rate in respect to the manual interpretation. Station velocities were estimated for approximately 270 stations from daily position solutions. The lengths of time series varied between 3 and 20 years. Uncertainty levels of 0.10, 0.10, and 0.25 mm/y for the north, east, and up components respectively were reached with 10 years of data for more than 90 % of stations. The detailed understanding of the GNSS time series in the Nordic and Baltic countries will enhance the quality of the European and global terrestrial reference frame realisations, because some of the stations contribute with the same data to those solutions. The densified reference frame solutions will be utilised in the maintenance of the national geodetic reference frames, including deformation modelling and the development of the accurate coordinate transformations. This will ultimately extend the lifetime of the national reference frames like EUREF-FIN.

KW - GNSS

KW - terrestrial reference frames

KW - GNSS time series

KW - GNSS velocities

KW - ITRF

KW - satelliittipaikannus

KW - terrestriset vertauskehykset

KW - GNSS-aikasarjat

KW - GNSS-nopeudet

KW - GNSS

KW - terrestrial reference frames

KW - GNSS time series

KW - GNSS velocities

KW - ITRF

M3 - Doctoral Thesis

SN - 978-952-64-0770-8

SN - 978-951-48-0280-5

T3 - Aalto University publication series DOCTORAL THESES

PB - Aalto University

ER -

Reference frame densifications for Nordic and Baltic countries - From local analysis to common and consistent GNSS solutions

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

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