ABSTRACT. We describe field measurements (ground-penetrating radar (GPR), geodetic survey and ice-core drilling) to provide new information on the movement mechanism and internal structure of a polar rock glacier on James Ross Island, Antarctic Peninsula. We collected GPR data along longitudinal and transverse profiles. The longitudinal GPR profiles identify inter-bedded debris-rich layers that dip up-glacier, similar to the thrust structures in the compression zone of a valley glacier. The transverse GPR profiles indicate a syncline structure inclined towards the central part of the rock glacier, resembling the transverse foliation of a valley glacier. The stratigraphy of two boreholes shows that the rock glacier consists primarily of bubbly ice with thin debris-rich layers, an internal structure similar to the 'nested spoons' structure common in the interior of valley glaciers. These results indicate that the glacier motion is controlled by shear movement, common in valley glaciers. The geodetic survey confirms that flow velocities decrease towards the lower part of the rock glacier. Such heterogeneous movement causes longitudinal compression and forms thrusts which then create the debris-rich layer by uplifting basal ice and debris. Pushing of the upstream ice against the downstream ice bends the surface layers, forming transverse ridges on the rock glacier surface.

As part of the terrestrial branch of the Japanfunded Arctic Climate Change Research Project (GRENE-TEA), which aims to clarify the role and function of the terrestrial Arctic in the climate system and assess the influence of its changes on a global scale, this model intercomparison project (GTMIP) is designed to (1) enhance communication and understanding between the modelling and field scientists and (2) assess the uncertainty and variations stemming from variability in model implementation/design and in model outputs using climatic and historical conditions in the Arctic terrestrial regions. This paper provides an overview of all GTMIP activity, and the experiment protocol of Stage 1, which is site simulations driven by statistically fitted data created using the GRENE-TEA site observations for the last 3 decades. The target metrics for the model evaluation cover key processes in both physics and biogeochemistry, including energy budgets, snow, permafrost, phenology, and carbon budgets. Exemplary results for distributions of four metrics (annual mean latent heat flux, annual maximum snow depth, gross primary production, and net ecosystem production) and for seasonal transitions are provided to give an outlook of the planned analysis that will delineate the inter-dependence among the key processes and provide clues for improving model performance. Published by CopernicusPublications on behalf of the European Geosciences Union. 2842 S. Miyazaki et al.: GTMIP: overview and experiment protocol for Stage 1 Geosci. Model Dev., 8, 2841-2856, 2015 www.geosci-model-dev.net/8/2841/2015/

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High-resolution maps of potential frozen ground distribution in South America have been produced for the present day (0 ka) and the Last Glacial Maximum (21 ka). Surface air temperature outputs from global climate models (GCMs) of the recent Paleoclimate Model Intercomparison Project were used for the reconstructions, and then downscaled from regional to local scales, with the help of a 1 arc-minute digital elevation model. Their validity was examined using fieldwork-based evidence and knowledge. The downscaled map for the present day successfully reproduces the presence of permafrost in the Andes, a task at which original coarse-resolution GCM output maps failed. The map also shows close correspondence with instrumental observations. Similarly, the downscaled distribution of 21 ka frozen ground shows overall consistency with geomorphological and/or palaeoenvironmental reconstructions. Areal coverage of potential permafrost for all of South America is estimated at 139 000 km 2 for today and 435 000 km 2 for 21 ka, mostly along the Andean mountain ranges. Regional inspections, however, show divergence from field-observed features, attributed to microclimatic effects and past permafrost conditions. For southern Patagonia, and especially the eastern lowlands, the diagnosed lower limit for permafrost is about 1000 m asl, whereas field evidence at lower altitudes indicates the presence of either permafrost or deep seasonal frost. Figure 1 Topography of South America examined in this study for (A) the present day and (B) the Last Glacial Maximum period, for which sea level is lowered by 127 m. Colours show altitude (m asl). In (B), the modern coastline is drawn as a thin black line for reference. Explanations of sites (S1-S7) are given in Table 2. This figure is available in colour online at wileyonlinelibrary.com/journal/ppp 44 K. Saito et al.