Audru GNSS püsijaama stabiilsuse kontrollimine InSAR kaugseire põhjal määratud maapinna deformatsioonidega
Laen...
Kuupäev
2021
Kättesaadav alates
10.09.2021
Autorid
Taaleš, Tauri
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Tänapäeval kasutatakse üha enam suuremate maa-alade parameetrite uurimiseks kaugseiret. Seoses kaugseire meetodite rohkem kasutusele võtmisega on aktuaalne uurida, kas selliseid meetodeid on optimaalne kasutada ka väiksema mastaabiga alade juures. Käesoleva magistritöö eesmärgiks on kontrollida Eestis Audru GNSS püsijaama stabiilsust interferomeetrilise tehisavaradari (InSAR) kaugseire meetodi abil määrates maapinna deformatsioone selle ümbruses. Eesmärgi saavutamiseks on hangitud satelliitradari Sentinel-1 poolt loodud maapinna kujutisi aastatel 2015-2021 ning neid interferomeetriliselt (InSAR meetodil) töödeldud. Referentspinnana on kasutatud 2015. aasta 13. jaanuari Pärnu maakonna kujutist, mille suhtes on arvutatud maapinna nihked ülejäänud kujutiste põhjal. Tulemusena on saadud maapinna deformatsioonid Pärnu maakonnas ning Audru GNSS püsijaama ümbruses. Kasutades programmi SNAP on aastate kaupa visualiseeritud keskmiste nihete kaardid Pärnu maakonnas ning arvutatud statistilised näitajad nihete kohta Audru GNSS püsijaama ümbruses. Statistiliste näitajatena on arvutatud nihete aritmeetiline keskmine, minimum, maksimum ning standardhälve. Aastate kaupa on koostatud ka aegrea graafikud nihete ning koherentsuse näitaja kohta. Saavutatud tulemuste põhjal võib väita, et uuritud aastatel on Pärnu maakonnas toimunud pigem maapinna vajumine, eriti uuritava ala keskosas. Maapinna kerkimine on esinenud looduskaitsealadel ning rannikualadel. Nihked on olnud vahemikus -15,8 cm kuni +9 cm. Audru püsijaama ümbruses on maapinna liikumine olnud üsna stabiilne (nihked vahemikus -3 ja -4 cm), v.a. 2017. ja 2019. aastal. Aritmeetilised keskmised on antud aastatel olnud vastavalt -1,5 cm ja -6,9 cm. Kokkuvõtes saab öelda, et Audru GNSS püsijaama ümbruses on maapind üsna stabiilne. Suuremad varieeruvused on esinenud ainult aastatel 2015 ja 2019. Koherentsusnäitajatest võib järeldada, et suures osas on näitaja kehvem olnud talvel, kesksuvel ning sügisel. Selle põhjuseks võivad olla atmosfäärist tingitud vead, näiteks talvel ja sügisel on suurem niiskus. Samuti võivad tulemused olla mõjutatud taimkatte kasvust (kesksuvel). Paremate tulemute saavutamiseks oleks võimalik töödeldud piltide arvu suurendada ning ajalist jaotust vähendada või kasutada satelliitpiltide töötlemiseks püsipeegeldajate meetodit.
Today, remote sensing is increasingly used to study the parameters of larger land areas. With the increasing use of remote sensing methods, it is important to examine whether it is optimal to use such methods in smaller areas as well. The aim of this master's thesis is to check the stability of the Audru GNSS permanent station in Estonia by using the Interferometric synthetic-aperture radar (InSAR) remote sensing method by determining the deformations of the ground around it. To achieve this goal, ground images created by satellite radar Sentinel-1 in 2015-2021 have been obtained and processed interferometrically (InSAR method). The image of Pärnu County of 13 January 2015 has been used as the reference surface, for which the ground displacements have been calculated on the basis of the remaining images. As a result, ground deformations have been obtained in Pärnu County and around the Audru GNSS fixed station. Using the SNAP program, maps of average displacements in Pärnu county have been visualized by years, and statistical indicators of displacements around the Audru GNSS fixed station have been calculated. The arithmetic mean, minimum, maximum and standard deviation of displacements have been calculated as statistical indicators. Time series graphs for the deformations and the coherence indicator have also been compiled. Based on the results, it can be stated that in the studied years there has rather been a subsidence of the ground in Pärnu county, especially in the central part of the studied area. Ground uplift has occurred in nature reserves and coastal areas. The displacements have been between -15.8 cm and +9 cm. In the vicinity of the Audru station, the movement has been quite stable (displacements between -3 and -4 cm), except for 2017 and 2019. The arithmetic means have been -1.5 cm and -6.9 cm, respectively. In conclusion, it can be said that the ground around the Audru GNSS fixed station is quite stable. Larger variations have occurred only in 2015 and 2019. It can be concluded from the coherence indicators that to a large extent the indicator has been worse in winter, mid-summer and fall. This may be due to atmospheric errors, such as higher humidity in winter and fall. The results may also be affected by vegetation growth (mid-summer). For better results, it would be possible to increase the number of processed images and reduce the time distribution, or to use the method of persistent scatterers to process satellite images.
Today, remote sensing is increasingly used to study the parameters of larger land areas. With the increasing use of remote sensing methods, it is important to examine whether it is optimal to use such methods in smaller areas as well. The aim of this master's thesis is to check the stability of the Audru GNSS permanent station in Estonia by using the Interferometric synthetic-aperture radar (InSAR) remote sensing method by determining the deformations of the ground around it. To achieve this goal, ground images created by satellite radar Sentinel-1 in 2015-2021 have been obtained and processed interferometrically (InSAR method). The image of Pärnu County of 13 January 2015 has been used as the reference surface, for which the ground displacements have been calculated on the basis of the remaining images. As a result, ground deformations have been obtained in Pärnu County and around the Audru GNSS fixed station. Using the SNAP program, maps of average displacements in Pärnu county have been visualized by years, and statistical indicators of displacements around the Audru GNSS fixed station have been calculated. The arithmetic mean, minimum, maximum and standard deviation of displacements have been calculated as statistical indicators. Time series graphs for the deformations and the coherence indicator have also been compiled. Based on the results, it can be stated that in the studied years there has rather been a subsidence of the ground in Pärnu county, especially in the central part of the studied area. Ground uplift has occurred in nature reserves and coastal areas. The displacements have been between -15.8 cm and +9 cm. In the vicinity of the Audru station, the movement has been quite stable (displacements between -3 and -4 cm), except for 2017 and 2019. The arithmetic means have been -1.5 cm and -6.9 cm, respectively. In conclusion, it can be said that the ground around the Audru GNSS fixed station is quite stable. Larger variations have occurred only in 2015 and 2019. It can be concluded from the coherence indicators that to a large extent the indicator has been worse in winter, mid-summer and fall. This may be due to atmospheric errors, such as higher humidity in winter and fall. The results may also be affected by vegetation growth (mid-summer). For better results, it would be possible to increase the number of processed images and reduce the time distribution, or to use the method of persistent scatterers to process satellite images.
Kirjeldus
Magistritöö
Geodeesia, kinnisvara- ja maakorralduse õppekaval
Märksõnad
magistritööd, radar, kaugseire, interferomeetriline tehisavaradar