Deriving the response of glaciers from an ice-dynamic model

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

Coupling a global glacier model to a global hydrological model prevents underestimation of glacier runoff

Global hydrological models have become a valuable tool for a range of global impact studies related to water resources. However, glacier parameterization is often simplistic or non-existent in global hydrological models. By contrast, global glacier models do represent complex glacier dynamics and glacier evolution, and as such, they hold the promise of better resolving glacier runoff estimates. In this study, we test the hypothesis that coupling a global glacier model with a global hydrological model leads to a more realistic glacier representation and, consequently, to improved runoff predictions in the global hydrological model. To this end, the Global Glacier Evolution Model (GloGEM) is coupled with the PCRaster GLOBal Water Balance model, version 2.0 (PCR-GLOBWB 2), using the eWaterCycle platform. For the period 2001–2012, the coupled model is evaluated against the uncoupled PCR-GLOBWB 2 in 25 large-scale (>50 000 km2), glacierized basins. The coupled model produces higher runoff estimates across all basins and throughout the melt season. In summer, the runoff differences range from 0.07 % for weakly glacier-influenced basins to 252 % for strongly glacier-influenced basins. The difference can primarily be explained by PCR-GLOBWB 2 not accounting for glacier flow and glacier mass loss, thereby causing an underestimation of glacier runoff. The coupled model performs better in reproducing basin runoff observations mostly in strongly glacier-influenced basins, which is where the coupling has the most impact. This study underlines the importance of glacier representation in global hydrological models and demonstrates the potential of coupling a global hydrological model with a global glacier model for better glacier representation and runoff predictions in glacierized basins

Large hydropower and water-storage potential in future glacier-free basins

Climate change is causing widespread glacier retreat1, and much attention is devoted to negative impacts such as diminishing water resources2, shifts in runoff seasonality3, and increases in cryosphere-related hazards4. Here we focus on a different aspect, and explore the water-storage and hydropower potential of areas that are expected to become ice-free during the course of this century. For roughly 185,000 sites that are glacierized at present, we predict the potentially emerging reservoir storage volume and hydropower potential. Using a climate-driven glacier- evolution model5 and topographical analysis6, we estimate a theoretical maximal total storage and hydropower potential of 875 ± 260 cubic kilometres and 1,355 ± 515 terawatt-hours per year, respectively (95% confidence intervals). A first-order suitability assessment that takes into account environmental, technical and economic factors identifies roughly 40 per cent of this potential (355 ± 105 cubic kilometres and 533 ± 200 terawatt-hours per year) as possibly being suitable for realization. Three quarters of the potential storage volume is expected to become ice-free by 2050, and the storage volume would be enough to retain about half of the annual runoff leaving the investigated sites. Although local impacts would need to be assessed on a case- by-case basis, the results indicate that deglacierizing basins could make important contributions to national energy supplies in several countries, particularly in High Mountain Asia

Future shifts in extreme flow regimes in Alpine regions

Extreme low and high flows can have negative economic, social, and ecological effects and are expected to become more severe in many regions due to climate change. Besides low and high flows, the whole flow regime, i.e., annual hydrograph comprised of monthly mean flows, is subject to changes. Knowledge on future changes in flow regimes is important since regimes contain information on both extremes and conditions prior to the dry and wet seasons. Changes in individual low- and high-flow characteristics as well as flow regimes under mean conditions have been thoroughly studied. In contrast, little is known about changes in extreme flow regimes. We here propose two methods for the estimation of extreme flow regimes and apply them to simulated discharge time series for future climate conditions in Switzerland. The first method relies on frequency analysis performed on annual flow duration curves. The second approach performs frequency analysis of the discharge sums of a large set of stochastically generated annual hydrographs. Both approaches were found to produce similar 100-year regime estimates when applied to a data set of 19 hydrological regions in Switzerland. Our results show that changes in both extreme low- and high-flow regimes for rainfall-dominated regions are distinct from those in melt-dominated regions. In rainfall-dominated regions, the minimum discharge of low-flow regimes decreases by up to 50 %, whilst the reduction is 25 % for high-flow regimes. In contrast, the maximum discharge of low- and high-flow regimes increases by up to 50 %. In melt-dominated regions, the changes point in the other direction than those in rainfall-dominated regions. The minimum and maximum discharges of extreme regimes increase by up to 100 % and decrease by less than 50  %, respectively. Our findings provide guidance in water resource planning and management and the extreme regime estimates are a valuable basis for climate impact studies

Report of the JARE-54 and BELARE 2012-2013 joint expedition to collect meteorites on the Nansen Ice Field, Antarctica

第54次日本南極地域観測隊員4名とベルギー南極観測隊員6 名の合計10名から構成される隕石探査隊は，2012年12月から2013年2月まで，セール・ロンダーネ山地南部に広がるナンセン氷原（南緯72°30′-73°，東経23°-25°，標高約2900-3000m）において隕石探査を実施した．ナンセン氷原には2012年12月26日から2013年2月2日まで39日間滞在した．今回の探査域は第29次日本南極地域観測隊以降探査が行われていない．探査の結果，採集した隕石の総数は424個，合計重量は約70kgであった．隕石発見地点は携帯GPSに記録されたので，探査域における隕石の分布が明確になった．これは隕石集積機構解明のための基礎データだけでなく，今後の探査計画に活用できる．本稿は主に日本隊による準備期間を含む実施報告書である．This paper reports on a joint expedition (JARE-54 and BELARE 2012-2013) that conducted a search for meteorites on the Nansen Ice Field, Antarctica, in an area south of the Sor Rondane Mountains (72°30′-73°S, 23°-25°E; elevation 2900-3000 m). The expedition took place over a period of 39 days during the austral summer, between 26 December 2012 and 2 February 2013. The team consisted of ten members: three researchers and one field assistant from the 54th Japanese Antarctic Research Expedition (JARE-54), and five researchers and one field assistant from the Belgian Antarctic Expedition (BELARE) 2012-2013. Previously, this area had only been searched by JARE-29. The team collected 424 meteorites, which had a total weight of about 70 kg. The search tracks of the ten members of the expedition were recorded using hand-held GPS units, and this allowed the distribution of meteorites within the searched area to be mapped. The resultant data will be useful for planning future expeditions and can be used to clarify the meteorite concentration mechanism on the ice field. This paper focuses on the activities of JARE-54 during the joint expedition

[I] Why do we find so many meteorites on the Nansen blue ice field and where else could we look?

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. / 2F Auditorium, National Institute of Polar Researc

Greenland and Canadian Arctic ice temperature profiles database

Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally available here for the first time. These newly available profiles, which are associated with pre-2010 boreholes, have been submitted by community members or digitized from published graphics and/or data tables. All 95 profiles are now made available in both absolute (meters) and normalized (0 to 1 ice thickness) depth scales and are accompanied by extensive metadata. These metadata include a transparent description of data provenance. The ice temperature profiles span 70 years, with the earliest profile being from 1950 at Camp VI, West Greenland. To highlight the value of this database in evaluating ice flow simulations, we compare the ice temperature profiles from the Greenland ice sheet with an ice flow simulation by the Parallel Ice Sheet Model (PISM). We find a cold bias in modeled near-surface ice temperatures within the ablation area, a warm bias in modeled basal ice temperatures at inland cold-bedded sites, and an apparent underestimation of deformational heating in high-strain settings. These biases provide process level insight on simulated ice temperatures

Statistical modelling of the surface mass-balance variability of the Morteratsch glacier, Switzerland: strong control of early melting season meteorological conditions

In this study we analyse a 15-year long time series of surface mass-balance (SMB) measurements performed between 2001 and 2016 in the ablation zone of the Morteratsch glacier complex (Engadine, Switzerland). For a better understanding of the SMB variability and its causes, multiple linear regressions analyses are performed with temperature and precipitation series from nearby meteorological stations. Up to 85% of the observed SMB variance can be explained by the mean May–June–July temperature and the total precipitation from October to March. A new method is presented where the contribution of each month's individual temperature and precipitation to the SMB can be examined in a total sample of 224 (16.8 million) combinations. More than 90% of the observed SMB can be explained with particular combinations, in which the May–June–July temperature is the most recurrent, followed by October temperature. The role of precipitation is less pronounced, but autumn, winter and spring precipitation are always more important than summer precipitation. Our results indicate that the length of the ice ablation season is of larger importance than its intensity to explain year-to-year variations. The widely used June–July–August temperature index may not always be the best option to describe SMB variability through statistical correlation

Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble

Glaciers in the European Alps play an important role in the hydrological cycle, act as a source for hydroelectricity and have a large touristic importance. The future evolution of these glaciers is driven by surface mass balance and ice flow processes, of which the latter is to date not included explicitly in regional glacier projections for the Alps. Here, we model the future evolution of glaciers in the European Alps with GloGEMflow, an extended version of the Global Glacier Evolution Model (GloGEM), in which both surface mass balance and ice flow are explicitly accounted for. The mass balance model is calibrated with glacier-specific geodetic mass balances and forced with high-resolution regional climate model (RCM) simulations from the EURO-CORDEX ensemble. The evolution of the total glacier volume in the coming decades is relatively similar under the various representative concentrations pathways (RCP2.6, 4.5 and 8.5), with volume losses of about 47 %–52 % in 2050 with respect to 2017. We find that under RCP2.6, the ice loss in the second part of the 21st century is relatively limited and that about one-third (36.8 % ± 11.1 %, multi-model mean ±1σ) of the present-day (2017) ice volume will still be present in 2100. Under a strong warming (RCP8.5) the future evolution of the glaciers is dictated by a substantial increase in surface melt, and glaciers are projected to largely disappear by 2100 (94.4±4.4 % volume loss vs. 2017). For a given RCP, differences in future changes are mainly determined by the driving global climate model (GCM), rather than by the RCM, and these differences are larger than those arising from various model parameters (e.g. flow parameters and cross-section parameterisation). We find that under a limited warming, the inclusion of ice dynamics reduces the projected mass loss and that this effect increases with the glacier elevation range, implying that the inclusion of ice dynamics is likely to be important for global glacier evolution projections.ISSN:1994-0416ISSN:1994-042