Chronostratigraphy of the Larsen blue-ice area in northern Victoria Land, East Antarctica, and its implications for paleoclimate

In blue-ice areas (BIAs), deep ice is directly exposed at the surface, allowing for the cost-effective collection of large-sized old-ice samples. However, chronostratigraphic studies on blue-ice areas are challenging owing to fold and fault structures. Here, we report on a surface transect of ice with an undisturbed horizontal stratigraphy from the Larsen BIA, northern Victoria Land, East Antarctica. Ice layers defined by dust bands and ground-penetrating radar (GPR) surveys indicate a monotonic increase in age along the ice flow direction on the downstream side, while the upstream ice exhibits a potential repetition of ages on scales of tens of meters, which result from a complicated fold structure. Stable water isotopes (δ18Oice and δ2Hice) and components of the occluded air (i.e., CO2, N2O, CH4, δ15N–N2, δ18Oatm (=δ18O-O2), δO2/N2, δAr/N2​​​​​​​, 81Kr, and 85Kr) are analyzed for surface ice and shallow ice core samples. Correlating δ18Oice, δ18Oatm, and CH4 records from the Larsen BIA with ice from previously drilled ice cores indicates that the gas age at various shallow vertical coring sites ranges between 9.2–23.4 kyr BP, while the ice age sampled from the surface ranges from 5.6 to 24.7 kyr BP. Absolute radiometric 81Kr dating for the two vertical cores confirms ages within acceptable levels of analytical uncertainty. A tentative climate reconstruction suggests a large deglacial warming of 15 ± 5 ∘C (1σ) and an increase in snow accumulation by a factor of 1.7–4.6 (from 24.3 to 10.6 kyr BP). Our study demonstrates that BIAs in northern Victoria Land may help to obtain high-quality records for paleoclimate and atmospheric greenhouse gas compositions through the last deglaciation, although in general climatic interpretation is complicated by the need for upstream flow corrections, evidence for strong surface sublimation during the last glacial period, and potential errors in the estimated gas age–ice age difference.</p

The diffusive limit of the Vlasov-Fokker-Planck equation with the chemotactic sensitivity coupled to a parabolic equation

In this paper, we study the Vlasov-Fokker-Plank (VFP) equation coupled to the parabolic equation with the inclusion of the chemotactic sensitivity of the cells. The diffusive limit of the model to the Keller-Segel model with chemotaxis is investigated. In this process, we study the global existence of solutions in W-1,W-P and use energy and entropy estimates on weighted W-1,W-p of that model with a diffusive scaling. Based on this information, we deal with a diffusive limit for the model and its solution. (C) 2019 Elsevier Inc. All rights reserved.11Nsciescopu

Hybrid Model of Mathematical and Neural Network Formulations for Rolling Force and Temperature Prediction in Hot Rolling Processes

Steelmaking requires precise calculation at several steps of the manufacturing processes. We focus on the hot rolling process using Steckel mills, almost the end step in steel coil manufacturing. The rolling process is a type of plastic working in which a slab passes between two rolls and is stretched to reach the target thickness. It is necessary to predetermine the exact rolling force to obtain a coil with an accurate thickness after the rolling process. First, we introduced a machine learning model for calculating the rolling force, which can be used in-line in real plants. However, a direct calculation of the rolling force can cause stability problems, because the model output directly affects the process. In order to avoid such a problem, we determined a special temperature of the coil by inverse calculation of the classical mechanical model of hot rolling and set it as the model output value. As learning models, deep neural networks (DNN) and gradient boosting-based decision tree models were used. We preprocessed the collected process history data and added artificial features to the model input by creating physical variables used in the classical models. Moreover, to supplement the black-box nature of DNN, feature importance was analyzed from the decision tree model, and utilization and interpretation of each feature in the process are presented. Thus, our methods take advantage of both the classical mathematical model and the deep neural network model.11Ysciescopu

Velocity Anomaly of Campbell Glacier, East Antarctica, Observed by Double-Differential Interferometric SAR and Ice Penetrating Radar

Regional changes in the flow velocity of Antarctic glaciers can affect the ice sheet mass balance and formation of surface crevasses. The velocity anomaly of a glacier can be detected using the Double-Differential Interferometric Synthetic Aperture Radar (DDInSAR) technique that removes the constant displacement in two Differential Interferometric SAR (DInSAR) images at different times and shows only the temporally variable displacement. In this study, two circular-shaped ice-velocity anomalies in Campbell Glacier, East Antarctica, were analyzed by using 13 DDInSAR images generated from COSMO-SkyMED one-day tandem DInSAR images in 2010–2011. The topography of the ice surface and ice bed were obtained from the helicopter-borne Ice Penetrating Radar (IPR) surveys in 2016–2017. Denoted as A and B, the velocity anomalies were in circular shapes with radii of ~800 m, located 14.7 km (A) and 11.3 km (B) upstream from the grounding line of the Campbell Glacier. Velocity anomalies were up to ~1 cm/day for A and ~5 cm/day for B. To investigate the cause of the two velocity anomalies, the ice surface and bed profiles derived from the IPR survey crossing the anomalies were analyzed. The two anomalies lay over a bed hill along the glacial valley where stick-slip and pressure melting can occur, resulting in temporal variation of ice velocity. The bright radar reflection and flat hydraulic head at the ice bed of A observed in the IPR-derived radargram strongly suggested the existence of basal water in a form of reservoir or film, which caused smaller friction and the reduced variation of stick-slip motion compared to B. Crevasses began to appear at B due to tensile stress at the top of the hill and the fast flow downstream. The sporadic shift of the location of anomalies suggests complex pressure melting and transportation of the basal water over the bed hill

Time-lapse electrical resistivity tomography and ground penetrating radar mapping of the active layer of permafrost across a snow fence in Cambridge Bay, Nunavut Territory, Canada: correlation interpretation using vegetation and meteorological data

International audienc

CO2 in ice cores at core depth 1.95 m from Larsen blue ice area, East Antarctica

Blue ice areas (BIAs) have several advantages for reconstructing past climate. However, the complicated ice flow in the areas hinders constraining the age. We apply state-of-the-art techniques and show that the ages cover the last deglaciation for Larsen BIA. Our study demonstrates that Larsen BIA in Northern Victoria Land helps in reconstructing the past climate during the last deglaciation. This data set presents gas composition (CO2, CH4, N2O, δ18Oatm, δ15N-N2, δO2/N2, δAr/N2), stable water isotopes (δ2Hice, δ18Oice), and the chronology of Larsen BIA. The ice cores were collected in January 2019 in Northern Victoria Land, East Antarctica. Gas composition analysis was conducted at Seoul National University and National Institute of Polar Research. Stable water isotopes were analyzed at Korea Polar Research Institute. Data sets were also published as a supplement of Lee et al. (2022) titled with “Chronostratigraphy of Larsen blue ice area in Northern Victoria Land, East Antarctica, and its implications for paleoclimate”, The Cryosphere

Properties of ice core #23 from Larsen blue ice area, East Antarctica

Blue ice areas (BIAs) have several advantages for reconstructing past climate. However, the complicated ice flow in the areas hinders constraining the age. We apply state-of-the-art techniques and show that the ages cover the last deglaciation for Larsen BIA. Our study demonstrates that Larsen BIA in Northern Victoria Land helps in reconstructing the past climate during the last deglaciation. This data set presents gas composition (CO2, CH4, N2O, δ18Oatm, δ15N-N2, δO2/N2, δAr/N2), stable water isotopes (δ2Hice, δ18Oice), and the chronology of Larsen BIA. The ice cores were collected in January 2019 in Northern Victoria Land, East Antarctica. Gas composition analysis was conducted at Seoul National University and National Institute of Polar Research. Stable water isotopes were analyzed at Korea Polar Research Institute. Data sets were also published as a supplement of Lee et al. (2022) titled with “Chronostratigraphy of Larsen blue ice area in Northern Victoria Land, East Antarctica, and its implications for paleoclimate”, The Cryosphere