ALBERT

Description: For a better global coverage of SLR (Satellite Laser Ranging) stations, We have formed an industry-government-academia research group in Japan and have designed and integrated a very minimum system for SLR. The basic concepts are small-size and low-cost in contrast to the majority of the existing SLR stations. As of early 2023, we have not tested actual ranging observations to SLR satellites yet, but we have finished testing its core components such as a laser, a timer and a telescope mount, and we are currently assembling these components and developing software. This project is linked with airbourne/satellite optical communications where high precision optical tracking is essential, and the deployment to the Antarctica is also under consideration.

Description: The deformation of the Earth's crust in Antarctica caused by Glacial Isostatic Adjustment (GIA) is highly dependent on the melting history of ice and the viscoelastic properties of the mantle. However, geodetic observations, including Global Navigation Satellite System (GNSS) measurements, are essential in constraining GIA model parameters. The Japanese Antarctic Research Expedition has conducted GNSS observations and absolute gravity measurements for over 20 years along the coast of Lützow-Holm Bay in East Antarctica, mainly at Syowa Station. This study aims to examine the geodetic signals associated with GIA from the observations made along the coast of Lützow-Holm Bay. Furthermore, the study involves numerical simulations of the signals based on the recently reported rapid ice thinning in this region during the mid-Holocene (Kawamata et al., 2020, QSR). According to Kawamata's paper, the target region underwent a rapid ice thinning of over 400 m from about 9 to 6 ka, as evidenced by geomorphological surveys and surface exposure ages. The representative deglaciation models, such as ICE-6G, do not incorporate this rapid thinning process. Therefore, the study examines the variability of the geodetic signals using the ice history, including rapid thinning. The predictions indicate that the modified ice history produces consistent results with the observations, thus supporting the occurrence of rapid ice melting during the Holocene. The results also suggest that geodetic observations can aid in constraining the ice sheet melting process in this region. Additionally, the study presents a similar analysis of gravity variations obtained from absolute gravity measurements at Syowa Station.