Exploring non-tidal loading deformation correction in GNSS time series analysis using GAMIT/GLOBK

• Main Authors: Khorrami, F., Nordman, M., Ejigu, Y., Lahtinen, S., Näränen, j., Bilker-Koivula, M., Raja-Halli, A.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Fennoscandia
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5019427

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.