Satelliidi Sentinel-3 altimeetria andmete valideerimine Lääne-Eesti rannikulähedastel aladel
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Kuupäev
2019
Kättesaadav alates
12.09.2019
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Magistritöö eesmärgiks on satelliitide Sentinel-3A ja Sentinel-3B altimeetria andmete
valideerimine Lääne-Eesti rannikulähedastel aladel GNSS mõõtmiste ning
veemõõdujaama andmete abil. Töö eesmärgi täitmiseks on Eesti Maaülikooli
õppejõudude Aive Liibusk ja Kristina Türk poolt teostatud välimõõtmised Läänemerel
ning Dirhami sadamas. Töö autor kogus Sentinel-3A ja Sentinel-3B altimeetria andmed
vastavalt juuni 2016 kuni detsember 2018 (Sentinel-3A) ja detsember 2018 kuni märts
2019 (Sentinel-3B) ajavahemike kohta.
Altimeetria andmete valideerimiseks on nii välimõõtmiste käigus saadud andmed kui ka
altimeetria andmed eelnevalt filtreeritud ja puhastatud. Altimeetria ja veemõõdujaama
andmete omavaheliseks võrdluseks on GNSS mõõtmisi kasutades leitud kõrguste erinevus
Dirhami veemõõdujaama ja valideerimispunktide vahel (ΔGNSS). Samuti on leitud ESTGEOID2017 kõrguslik muutus Dirhami veemõõdujaama ja valideerimispunktide vahel
(Δgeoid). Lisaks eelnimetatud paranditele on kõrguste võrdlemise juures arvestatud ka
merepinna hetke topograafiaga (ΔHBM-EST). Leitud parandeid kasutades arvutati
veetaseme kõrgused valideerimispunktidesse iga valitud ülelennu jaoks.
Kõrguste võrdlemise tulemusena leiti, et Sentinel-3A altimeetria andmed on võimalik
Läänemere rannikulähedases piirkonnas saada 0,04 ± 0,13 m (SSHA - SSHgeoid) ja 0,04 ±
0,14 m (SSHA – SSHGNSS) täpsusega ning Sentinel-3B andmed 0,13 ± 0,09 m (SSHA -
SSHgeoid) ja 0,14 ± 0,09 m (SSHA – SSHGNSS) täpsusega. Sentinel-3B andmete halvem
täpsus on tingitud vähesest ülelendude arvust ning valitud ülelendude sattumisest talvisele perioodile, kus segavaks faktoriks on jääkate Läänemerel. Olgugi, et Sentinel-3A puhul
saavutati üsna hea täpsus, ei saa öelda, et satelliitaltimeetria abil on võimalik määrata
merepinna kõrgus sama täpselt kui veemõõdujaamadega. Küll aga saame öelda, et
satelliitaltimeetria abil on merepinna kõrguse määramine ulatuslikum ning soodsam.
The aim of this thesis is absolute validation of satellites Sentinel-3A and Sentinel-3B altimetry data on the coastal area of West-Estonia using the GNSS measurements and tide gauge (TG) data. To complete the task at hand two lectors of Estonian University of Life Sciences Aive Liibusk and Kristina Türk have done measurements on the Baltic sea and the port of Dirhami. In addition there is altimetry data gathered by the author of the thesis of Sentinel-3A and Sentindel-3B. To validate altimetry data GNSS measurements and gathered altimetry data that has been filered and purified before. The comparison of altimetry and tide gauge data is based on the difference between the altitudes found using GNSS measurements between the Dirhami’s TG and the validation points (ΔGNSS). What has also been found is the high change in the EST-GEOID2017 between Dirhami’s TG and validation points(Δgeoid). In addition to the above corrections sea surface topography is also taken into account when comparing heights (ΔHBM-EST). Based on the discovered parameters the water level was calculated into validation points for each pass. Comparing the height measurements it was discovered that Sentinel-3A altimetry data is possible to recieve with the accuracy of 0,04 ± 0,13 (SSHA - SSHgeoid) and 0,04 ± 0,14 (SSHA – SSHGNSS method) and Sentinel-3B data with the accuracy of 0,13 ± 0,09 (SSHA - SSHgeoid method) and 0,14 ± 0,09 (SSHA – SSHGNSS method).Sentinel-3B’s bad accuracy is due to fewer number passes and choosing the passes schedule to be set on the winter period, where the interfering factor is the cover of ice on the Baltic Sea. As it may be, the Sentinel-3A achieved a decent accuracy, we can’t say that using the satellite altimetry it is possible to pinpoint the sea level as accurately as with tide gauges. However we can say that using satellite altimetry we can get a far more extensive and cheaper assessment than using tide gauges.
The aim of this thesis is absolute validation of satellites Sentinel-3A and Sentinel-3B altimetry data on the coastal area of West-Estonia using the GNSS measurements and tide gauge (TG) data. To complete the task at hand two lectors of Estonian University of Life Sciences Aive Liibusk and Kristina Türk have done measurements on the Baltic sea and the port of Dirhami. In addition there is altimetry data gathered by the author of the thesis of Sentinel-3A and Sentindel-3B. To validate altimetry data GNSS measurements and gathered altimetry data that has been filered and purified before. The comparison of altimetry and tide gauge data is based on the difference between the altitudes found using GNSS measurements between the Dirhami’s TG and the validation points (ΔGNSS). What has also been found is the high change in the EST-GEOID2017 between Dirhami’s TG and validation points(Δgeoid). In addition to the above corrections sea surface topography is also taken into account when comparing heights (ΔHBM-EST). Based on the discovered parameters the water level was calculated into validation points for each pass. Comparing the height measurements it was discovered that Sentinel-3A altimetry data is possible to recieve with the accuracy of 0,04 ± 0,13 (SSHA - SSHgeoid) and 0,04 ± 0,14 (SSHA – SSHGNSS method) and Sentinel-3B data with the accuracy of 0,13 ± 0,09 (SSHA - SSHgeoid method) and 0,14 ± 0,09 (SSHA – SSHGNSS method).Sentinel-3B’s bad accuracy is due to fewer number passes and choosing the passes schedule to be set on the winter period, where the interfering factor is the cover of ice on the Baltic Sea. As it may be, the Sentinel-3A achieved a decent accuracy, we can’t say that using the satellite altimetry it is possible to pinpoint the sea level as accurately as with tide gauges. However we can say that using satellite altimetry we can get a far more extensive and cheaper assessment than using tide gauges.
Kirjeldus
Magistritöö
Geodeesia ja maakorralduse õppekaval
Märksõnad
magistritööd, satelliitaltimeetria, kaugseire, Läänemeri, veemõõdujaamad, valideerimine