17:15 〜 18:30
[SGD01-P07] GIA signal detected by GNSS observation along the coast of Lützow-Holm Bay
キーワード：Glacial Isostatic Adjustment、GRACE、GNSS
The viscoelastic deformation caused by the ice-sheet mass change since the Last Glacial Maximum, i.e. Glacial Isostatic Adjustment (GIA), is one of the most significant error sources of the estimated recent Antarctic ice sheet mass change by GRACE/GRACE-FO. It is important to detect the GIA signal included in the current crustal deformation or gravity change obtained by the geodetic observations to constrain and improve GIA models.
The Japanese Antarctic Research Expedition (JARE) has been conducting GNSS (Ohzono et al., 2006) and gravity observations (Kazama et al., 2013) in the outcrop area along the coast of Lützow-Holm Bay (69°S 37°E), East Antarctica. Besides, Lützow-Holm Bay is one of the few areas where the detailed temporal change of ice-sheet thickness during the last deglaciation has been reported from geomorphological studies (Kawamata et al., 2020). Therefore, this region is considered suitable for discussing GIA, as various studies have been conducted in this area.
In this study, we analyzed the GNSS observation data obtained at the 5 sites along Lützow-Holm Bay from 2010 to 2018. We corrected the elastic deformation component from the recent surface mass variation estimated by GRACE to detect the crustal deformation caused by GIA. Besides, the expected vertical velocity at each station was calculated with three GIA models, ANU (Lambeck et al., 2014), ICE-5G (Peltier, 2004), and ICE-6G_C (Peltier et al., 2015), and compared with the GNSS results.
We performed static precise point positioning (PPP) analysis using "c5++" (Otsubo et al., 2019) for the GNSS observation data obtained at five sites: SYOG, an IGS station in Syowa Station, and Langhovde, Skarvsness, Padda, and Rundvågshetta, outcrop stations along the coast of Lützow-Holm Bay. The estimated vertical velocities varied from 1 to 4 mm/yr, and all of them showed uplift. This vertical velocity estimated by GNSS includes the elastic deformation component caused by the surface mass increase due to recent snow accumulation, so the elastic deformation component was corrected assuming the GRACE mascon solution as a present load change. The JPL RL06 Mascon solution from 2010 to 2017 shows a continuous surface mass increase around this region, in which the elastic deformation is a subsidence of about 1 mm/yr simultaneously. After this correction of elastic deformation, the uplift due to GIA in Lützow-Holm Bay is estimated to be about 1-6 mm/year.
The uplift rates of ANU, ICE-5G, and ICE-6G are compared with the GNSS results with varying the mantle velocities. The comparison shows that the calculated uplift rates of ANU and ICE-5G are much lower than the observed uplift rates, while those of ICE-6G_C are relatively consistent.
The Japanese Antarctic Research Expedition (JARE) has been conducting GNSS (Ohzono et al., 2006) and gravity observations (Kazama et al., 2013) in the outcrop area along the coast of Lützow-Holm Bay (69°S 37°E), East Antarctica. Besides, Lützow-Holm Bay is one of the few areas where the detailed temporal change of ice-sheet thickness during the last deglaciation has been reported from geomorphological studies (Kawamata et al., 2020). Therefore, this region is considered suitable for discussing GIA, as various studies have been conducted in this area.
In this study, we analyzed the GNSS observation data obtained at the 5 sites along Lützow-Holm Bay from 2010 to 2018. We corrected the elastic deformation component from the recent surface mass variation estimated by GRACE to detect the crustal deformation caused by GIA. Besides, the expected vertical velocity at each station was calculated with three GIA models, ANU (Lambeck et al., 2014), ICE-5G (Peltier, 2004), and ICE-6G_C (Peltier et al., 2015), and compared with the GNSS results.
We performed static precise point positioning (PPP) analysis using "c5++" (Otsubo et al., 2019) for the GNSS observation data obtained at five sites: SYOG, an IGS station in Syowa Station, and Langhovde, Skarvsness, Padda, and Rundvågshetta, outcrop stations along the coast of Lützow-Holm Bay. The estimated vertical velocities varied from 1 to 4 mm/yr, and all of them showed uplift. This vertical velocity estimated by GNSS includes the elastic deformation component caused by the surface mass increase due to recent snow accumulation, so the elastic deformation component was corrected assuming the GRACE mascon solution as a present load change. The JPL RL06 Mascon solution from 2010 to 2017 shows a continuous surface mass increase around this region, in which the elastic deformation is a subsidence of about 1 mm/yr simultaneously. After this correction of elastic deformation, the uplift due to GIA in Lützow-Holm Bay is estimated to be about 1-6 mm/year.
The uplift rates of ANU, ICE-5G, and ICE-6G are compared with the GNSS results with varying the mantle velocities. The comparison shows that the calculated uplift rates of ANU and ICE-5G are much lower than the observed uplift rates, while those of ICE-6G_C are relatively consistent.