Validation of grounding line of the East Antarctic Ice Sheet derived by ERS-1/2 interferometric SAR data

We applied Synthetic Aperture Radar (SAR) Interferometry (InSAR) in the East Antarctic marginal ice zone between 25°W and 40°E . ERS-1/2 tandem data received at Syowa Station in 1996 were mainly used. ERS interferograms with range-azimuth coordinates were transformed into World Geodetic System 1984 (WGS84) coordinates. For this transform, we used the RAMP (RADARSAT Antarctic Mapping Project) image which is already defined by the WGS84 reference system. Significant features in the ERS intensity image show similar textures to those in the RAMP image. By taking the above features in the ERS intensity image as ground control points of known WGS84 geodetic coordinates from the RAMP image, we assigned WGS84 coordinate values to any element in the ERS scene by a least-squares fitting with a second-order polynomial function. It is noted that the ERS InSAR scene has the same WGS84 coordinate system as the ERS intensity scene. We extracted and digitized grounding lines from the ERS InSAR scene as a curve of steeply changing fringe pattern at the ocean-continent boundary. Features of the grounding line in the Antarctic Digital Database (ADD) were monotonous as interpreted from blurring of the Landsat image on the ice shelf and the ice sheet. In contrast, InSAR-derived grounding lines delineated complex features as a result of ocean tidal motion at the ocean-continent boundary. For example, the ADD shows a peninsula around 15°E , but it actually is a group of snow-covered islands or ice rises. The positional discrepancy of the ADD grounding line from the InSAR-derived grounding line reaches 5000m around Riiser-Larsenhalvya, and about 1200m around Padda and Skallen

Impact of satellite gravity missions on glaciology and Antarctic Earth sciences

Satellite gravity missions in the 21st Century are expected to be beneficial to multi-disciplinary scientific objectives. Especially, the Gravity Recovery And Climate Experiment (GRACE) and its follow-on missions will provide not only data for precise gravity mapping but also time series of global gravity field coefficients at intervals of about 15 days to two months. These data are precise enough to reveal the temporal variations of the gravity fields due to mass redistribution in and on the Earth. From the viewpoint of Earth sciences in the Antarctic region, the data are expected to contribute to studies of ice sheet mass balance and postglacial rebound as well as other geodetic and geophysical problems. These issues have been mainly investigated based on the degree variance analyses of the gravity field so far. In this paper, we briefly review the gravity mission data from the viewpoint of along track geoid height variations which are more direct results of the mass variations, and then discuss some of the issues related to in-situ observations

Ten years\u27 progress of Syowa Station, Antarctica, as a global geodesy network site

Progress of geodesy programs at Syowa Station since our former review in 1933 is summarized.As for Very Long Baseline Interferometry (VLBI),Global Positioning System (GPS),and Doppler Orbitography Radiopositioning Integrated by Satellites(DORIS),Syowa Station isa participating station in an international network and hasobtained an International Earth Rotation Service (IERS)dome number.Time series of about /years show change of position by plate motion. Detection of vertical motion by glacial isostatic adjustment is still under investigation. More than 20000 synthetic aperture radar (SAR) scenes have been received from the European Remote Sensing satellite-1 and -2 (ERS-1/-2) and the Japan Earth Resources satellite-1 (JERS-1) by the Syowa 11-m multipurpose antenna. Several case studies by interferometric SAR analyses have shown characteristic features of the ice grounding zones,ice dynamics and Digital Elevation Model (DEM)estimates.As for absolute gravimeter (AG) measurements, Syowa Station is registered as the International Absolute Gravity Basestation Network (IAGBN)0417 point. Observa tionswith an FG5 gravimeter were made for two summer seasons 5 years apart, and they showed consistent results within 2μGal difference. The superconducting gravimeter (SG) observations with a TT70 (#016 ) produced many scientific results in the two streamlines of tidal bands and normal mode bands.Especially, the first evidence of incessant excitation of the Earth \u27s free oscillations (background free oscillations)is noted as an important contribution from the Syowa SG observations.The Gravity Recovery And Climate Experiment (GRACE) satellite will bring an important advance for the study of ice-water-air mass circulation and its interaction with the solid-earth.The local potential fields calibrated by connecting to the station observatory data should give appropriate ground-truth information for the regional-scale satellite data,which reflects the continuing important role of Syow

JARE Syowa Station 11-m Antenna, Antarctica

In 2012, the 52nd and the 53rd Japanese Antarctic Research Expeditions (hereinafter, referred to as JARE-52 and JARE-53, respectively) participated in five OHIG sessions - OHIG76, 78, 79, 80, and 81. These data were recorded on hard disks through the K5 terminal. Only the hard disks for the OHIG76 session have been brought back from Syowa Station to Japan, in April 2012, by the icebreaker, Shirase, while those of the other four sessions are scheduled to arrive in April 2013. The data obtained from the OHIG73, 74, 75, and 76 sessions by JARE-52 and JARE-53 have been transferred to the Bonn Correlator via the servers of National Institute of Information and Communications Technology (NICT). At Syowa Station, JARE-53 and JARE-54 will participate in six OHIG sessions in 2013

Elastic deformation due to present-day mass change at GNSS measurements sites in East Antarctica

The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / 3F Seminar room, National Institute of Polar Researc

Installation of the superconducting gravimeter CT(#043) at Syowa Station, Antarctica

During the wintering period of the 44th Japanese Antarctic Research Expedition (JARE-44: February 2003 to January 2004), a new superconducting gravimeter CT(#043) with a cryocooler was installed and tested to replace the former TT70(#016) at Syowa Station, Antarctica. The CT(#043) has design sensitivity of 1nGal (1×10^(-11)m/s^2) to study the Earth\u27s dynamics in tidal and longer-period bands. A new type of diaphragm was used to effectively isolate the vibration from the refrigerator cold-head and to prevent solid air contamination from entering the Dewar. A real-time remote monitoring system including a Web camera for diagnostics from Japan has also been installed

Future efforts to contribute to the International Height Reference System (IHRS)

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR