Shirase Glacier is known to one of the fastest ice streams in Antarctic glaciers, and it is important to monitor the flow velocity of the glacier because of understanding the discharge of ice mass in Antarctica. The authors have shown that the flow velocity of Shirase Glacier can be estimated by applying the image correlation method to the amplitude images derived from the Phased Array type L-band Synthetic Aperture Radar type 2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2 (ALOS-2) [1]. In this paper, we show the validation results of the estimated flow velocity applied the image correlation method to the PALSAR-2 data, based on the flow velocity measured from the latitude and longitude information using the GNSS receiver on the ice radar (ApRES) simultaneously with the PALSAR-2 observation. As a result, the RMS error between the measured and estimated flow velocity of Shirase Glacier was 0.046 km a−1, and the estimated flow velocity obtained using the image correlation method applied to the PALSAR-2 data is proved to be in good agreement with the ground truth.

This study presents that temporal variations in ice flow velocities for Shirase Glacier and its surrounding landfast ice in Liitzow-Holm Bay, East Antarctica were estimated using synthetic aperture radar (SAR) images acquired by the Phased Array L-band SAR-2 (PALSAR-2) onboard Advanced Land Observing Satellite-2 (ALOS-2) in 2015-2018. The images were analyzed using image correlation. The flow velocity at the 20 km downstream from the grounding line (GL) of Shirase Glacier is mean of 2.32 km a-1in 2015-2018, which show that flow velocity is considered to be less related to the landfast ice stability. However, the flow velocity around 50 km downstream from the GL show changes related to landfast ice condition. The flow velocity is more increasable of 0.3 km a-1under the unstable landfast ice condition than the stable landfast ice condition. Therefore, our results show the velocity of Shirase Glacier are associated with the condition of landfast ice stability or instability.

MOTIVATION: Long expansions of short tandem repeats (STRs), i.e. DNA repeats of 2-6 nt, are associated with some genetic diseases. Cost-efficient high-throughput sequencing can quickly produce billions of short reads that would be useful for uncovering disease-associated STRs. However, enumerating STRs in short reads remains largely unexplored because of the difficulty in elucidating STRs much longer than 100 bp, the typical length of short reads. RESULTS: We propose ab initio procedures for sensing and locating long STRs promptly by using the frequency distribution of all STRs and paired-end read information. We validated the reproducibility of this method using biological replicates and used it to locate an STR associated with a brain disease (SCA31). Subsequently, we sequenced this STR site in 11 SCA31 samples using SMRT(TM) sequencing (Pacific Biosciences), determined 2.3-3.1 kb sequences at nucleotide resolution and revealed that (TGGAA)- and (TAAAATAGAA)-repeat expansions determined the instability of the repeat expansions associated with SCA31. Our method could also identify common STRs, (AAAG)- and (AAAAG)-repeat expansions, which are remarkably expanded at four positions in an SCA31 sample. This is the first proposed method for rapidly finding disease-associated long STRs in personal genomes using hybrid sequencing of short and long reads. AVAILABILITY AND IMPLEMENTATION: Our TRhist software is available at http://trhist.gi.k.u-tokyo.ac.jp/. CONTACT: [email protected] SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

The knowledge of accurate surface topography heights and ice dynamics is a key issue for mass flux and mass balance calculations. In this study we use interferometry to derive surface heights and horizontal ice flow velocities for grounded parts in Western Dronning Maud Land, Antarctica. Additionally, a feature and speckle tracking is performed to also estimate horizontal ice flow velocities for the Riiser-Larsen ice shelf and its grounding zone. This flow velocity field is afterwards used to remove the horizontal flow velocity component from the interferograms in order to obtain the vertical changes in the ice shelf area which are caused by ocean tides. The measured height changes are than compared to the predicted height changes of current ocean tide models which allow a validation of the models quality.

We have a plan to build the ocean-continent boundary database at Antarctica mainly to apply InSAR analysis technique using ERS-1 and ERS-2 tandem mission data. This database shows the snapshot of the state of Antarctic ice shelves and ice sheet in 1995-1996, when the tandem mission operated. The ocean-continent boundary data consist of grounding line and coast line, both which have vector property, and these vector data are stored by ESRI shape format (SHP), which is the world's standard vector format. This database will be expected to be used for ice mass flux study at Antarctica and is opened public on internet in this year to contribute the International Polar Year (IPY) activities and anyone can access this database freely through web browser.

We applied an image correlation method to the Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR) data obtained from 1996 to 1998. The obtained ice flow velocity was systematically larger on the western streamline than on the eastern streamline from the grounding line towards the downstream region. The differences were 0.28 km/a in 1996 and 0.33 km/a in 1998, which were significantly larger than the error estimate of 0.04 km/a. The ice flow direction was about 312° at the grounding line and changed to 327° at 10 km, 346° at 20 km and 2° at 30 km downstream from the grounding line. The total deflection attained 38° towards east.

This study aims to use ICESat /GLAS data for correction of DEM made from Interferometric SAR data instead of traditional ground control points (GCPs) collected by ground survey. GLAS is a laser altimeter system and it can measure the earth surface topography with ultimate vertical accuracy (plusmn14 cm) and high spatial accuracy (plusmn15 m). Therefore, we can treat GLAS data for the reference of height and position on Antarctic ice sheet. We applied this method at south of Breivika. The elevation values derived by ERS-1/2 InSAR DEM have insufficient height accuracy compared to GLAS data due to insufficient baseline estimation, ice flow appeared in the fringe pattern, and difficulty of phase unwrapping, which is RMS plusmn284.0 m compared with GLAS data. After the correction of InSAR DEM using GLAS data, it improved to plusmn32.6 m. Next, we validated this result using the 28thJARE (Japanese Antarctic Research Expedition) GPS survey result. The RMS height difference between JARE GPS result and corrected InSAR DEM showed plusmn39.5 m. The result showed that our correction method works quite well and we can produce spatially dense and high accuracy DEM along with Antarctic coast line. The one remaining problem is how to reduce the effect of ice flow appeared in the fringe pattern.