ALBERT

Description: Landfast ice thickness in the Canadian Arctic Archipelago from observations and models Stephen E. L. Howell, Frédéric Laliberté, Ron Kwok, Chris Derksen, and Joshua King The Cryosphere, 10, 1463-1475, doi:10.5194/tc-10-1463-2016, 2016 The Canadian Ice Service record of observed landfast ice and snow thickness represents one of the longest in the Arctic that spans over 5 decades. We analyze this record to report on long-term trends and variability of ice and snow thickness within the Canadian Arctic Archipelago (CAA). Results indicate a thinning of ice at several sites in the CAA. State-of-the-art climate models still have difficultly capturing observed ice thickness values in the CAA and should be used with caution.

Description: Increased nitrate and decreased δ 15 N–NO 3 − in the Greenland Arctic after 1940 attributed to North American oil burning Nathan J. Chellman, Meredith G. Hastings, and Joseph R. McConnell The Cryosphere Discuss., doi:10.5194/tc-2016-163,2016 Manuscript under review for TC (discussion: open, 0 comments) This manuscript analyzes the changing sources of nitrate deposition to Greenland since 1760 CE using a dataset consisting of sub-seasonally resolved nitrogen isotopes of nitrate and source tracers. Correlations amongst ion concentration, source tracers, and the δ 15 N–NO 3 − provide evidence of the impact of biomass burning and fossil fuel combustion emissions of nitrogen oxides and suggest that oil combustion is the likely driver of increased nitrate concentration in Greenland ice since 1940 CE.

Description: Response of seasonal soil freeze depth to climate change across China Xiaoqing Peng, Oliver W. Frauenfeld, Tingjun Zhang, Kang Wang, Bin Cao, Xinyue Zhong, Hang Su, and Cuicui Mu The Cryosphere Discuss., doi:10.5194/tc-2016-129,2016 Manuscript under review for TC (discussion: open, 0 comments) Previous researches paid more attention on the permafrost, e.g. active layer thickness, soil temperature, permafrost area extent, and associated with permafrost degradation leading other changes. However, seasonally frozen ground, vast area extent, did not focus by so much attention. Here, we combined more than 800 observation station data and gridded data to investigate soil freeze depth across China. The results indicate that soil freeze depth increase with climate warming.

Description: Circumpolar polynya regions and ice production in the Arctic: Results from MODIS thermal infrared imagery for 2002/2003 to 2014/2015 with a regional focus on the Laptev Sea Andreas Preußer, Günther Heinemann, Sascha Willmes, and Stephan Paul The Cryosphere Discuss., doi:10.5194/tc-2016-133,2016 Manuscript under review for TC (discussion: open, 0 comments) Our study presents spatial and temporal characteristics of 16 prominent polynya regions over the entire Arctic basin. By using an energy balance model, we are able to derive daily thin-ice thickness distributions from satellite and atmospheric reanalysis data. All polynyas combined yield an average ice production of about 1444 km 3 per winter. Interestingly, we find distinct regional differences in calculated trends over the last 13 years. Finally, we set a special focus on the Laptev Sea region.

Description: Comparison of the simulated upper-ocean vertical structure using 1-dimensional mixed-layer models Sonaljit Mukherjee and Amit Tandon Ocean Sci. Discuss., doi:10.5194/os-2016-45,2016 Manuscript under review for OS (discussion: open, 0 comments) Atmospheric fluxes influence the momentum and scalar properties in the upper-cean. Buoyancy fluxes result in a diurnal variability in the sea-surface temperature (SST), whereas the wind stress forms near-inertial currents in the mixed layer (ML). In this study, we investigate the contrasts between the simulated SST and the vertical structure of the temperature and shear by three different mixing models: the PWP bulk mixed-layer model, the KPP non-local boundary layer model and the κ−ϵ local mixing model. We choose two upper-ocean datasets for our studies, namely the SWAPP (1990) and the MLML (1991). The SWAPP dataset shows the presence of strong near-inertial shear below the ML and negligible near-inertial shear within the ML. The MLML dataset shows a negligible rise in the SST during the first 22 day mixing phase, which is followed by a steep rise by 6 °C during the subsequent 75 day restratification phase. Comparison with the SWAPP dataset shows that the KPP and κ−ϵ models form strong shear near the surface due to weak eddy viscosities, thus producing a thin shear layer over the entire range of frequencies in the wind stress. At the ML base, the models form an inertial and a diurnal maximum. The inertial maximum extends over a substantial range of depths, and is continuous for the κ−ϵ model but discontinuous for the KPP and PWP models. Comparison with the MLML dataset reveals that the KPP yields the largest SST amplitude over a 24-hour diurnal cycle, and is followed by the κ−ϵ and PWP. However, the net warming of SST at the end of the diurnal cycle is stronger for the PWP compared to κ−ϵ and KPP. The PWP also forms stronger temperature gradients at the ML base compared to κ−ϵ and KPP. Over multiple diurnal cycles, the shallowing and deepening of the mixed layer results in multiple sharp temperature gradients in PWP, thus forming a serrated vertical profile that remains unaffected during the restratification phase of the MLML dataset.

Description: Radiocarbon dating of glacier ice Chiara Uglietti, Alexander Zapf, Theo M. Jenk, Sönke Szidat, Gary Salazar, and Margit Schwikowski The Cryosphere Discuss., doi:10.5194/tc-2016-160,2016 Manuscript under review for TC (discussion: open, 0 comments) A meaningful interpretation of the climatic history contained in ice cores requires a precise chronology. For dating the older and deeper part of the glaciers, radiocarbon analysis can be used, when organic matter such as plant or insect fragments is found in the ice. Since this happens rarely, a complementary dating tool is based on radiocarbon dating of the insoluble fraction of carbonaceous aerosols entrapped in the ice, allowing dating ice with ages between 200 and more than 10 000 years.

Description: Wave climate in the Arctic 1992–2014: seasonality and trends Justin E. Stopa, Fabrice Ardhuin, and Fanny Girard-Ardhuin The Cryosphere, 10, 1605-1629, doi:10.5194/tc-10-1605-2016, 2016 Satellite observations show the Arctic sea ice has decreased the last 30 years. From our wave model hindcast and satellite altimeter datasets we observe profound increasing wave heights, which are caused by the loss of sea ice and not the driving winds. If ice-free conditions persist later into fall, then regions like the Beaufort–Chukchi Sea will be prone to developing larger waves since the driving winds are strong this time of year.

Description: Microstructure representation of snow in coupled snowpack and microwave emission models Melody Sandells, Richard Essery, Nick Rutter, Leanne Wake, Leena Leppänen, and Juha Lemmetyinen The Cryosphere Discuss., doi:10.5194/tc-2016-181,2016 Manuscript under review for TC (discussion: open, 0 comments) This study looks at a wide range of options for simulating sensor signals for satellite monitoring of water stored as snow, though an ensemble of 1323 coupled snow evolution and microwave scattering models. The greatest improvements will be made with better computer simulations of how the snow microstructure changes, followed by how the microstructure scatters radiation at microwave frequencies. Snow compaction should also be considered in systems to monitor snow mass from space.

Description: Brief communication: Organochlorine pesticides in an archived firn core from Law Dome, East Antarctica Marie Bigot, Mark A. J. Curran, Andrew D. Moy, Derek C. G. Muir, Darryl W. Hawker, Roger Cropp, Camilla F. Teixeira, and Susan Bengtson Nash The Cryosphere Discuss., doi:10.5194/tc-2016-178,2016 Manuscript under review for TC (discussion: open, 0 comments) Organochlorine pesticides (OCPs) were, for the first time, quantified in archived firn cores from the East Antarctic ice sheet representative of 1945–1957 C.E. and 1958–1967 C.E. The core sections were melted under high purity nitrogen atmosphere and the melt water analysed. Methods allowed quantification of hexachlorocyclohexanes, heptachlor, trans-chlordane, dieldrin and endrin. While the core presented evidence of nominal modern-use chemical contamination, indicating handling and/or storage contamination, legacy OCP concentrations and deposition rates reported are orders of magnitude lower than those from Arctic regions, lending support for their validity. The study further provides a description of equipment used and suggests adapted methods to overcome logistical challenges associated with trace organic contaminant detection in Polar Regions.

Description: Developing European operational oceanography for Blue Growth, climate change adaptation and mitigation, and ecosystem-based management Jun She, Icarus Allen, Erik Buch, Alessandro Crise, Johnny A. Johannessen, Pierre-Yves Le Traon, Urmas Lips, Glenn Nolan, Nadia Pinardi, Jan H. Reißmann, John Siddorn, Emil Stanev, and Henning Wehde Ocean Sci., 12, 953-976, doi:10.5194/os-12-953-2016, 2016 This white paper addresses key scientific challenges and research priorities for the development of operational oceanography in Europe for the next 5–10 years. Knowledge gaps and deficiencies are identified in relation to common scientific challenges in four EuroGOOS knowledge areas: European ocean observations, modelling and forecasting technology, coastal operational oceanography, and operational ecology.

Description: Statistical indicators of Arctic sea-ice stability – prospects and limitations Sebastian Bathiany, Bregje van der Bolt, Mark S. Williamson, Timothy M. Lenton, Marten Scheffer, Egbert H. van Nes, and Dirk Notz The Cryosphere, 10, 1631-1645, doi:10.5194/tc-10-1631-2016, 2016 We examine if a potential "tipping point" in Arctic sea ice, causing abrupt and irreversible sea-ice loss, could be foreseen with statistical early warning signals. We assess this idea by using several models of different complexity. We find robust and consistent trends in variability that are not specific to the existence of a tipping point. While this makes an early warning impossible, it allows to estimate sea-ice variability from only short observational records or reconstructions.

Description: Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014 Wenjun Yao and Jiuxin Shi Ocean Sci. Discuss., doi:10.5194/os-2016-54,2016 Manuscript under review for OS (discussion: open, 0 comments) Antarctic Intermediate Water (AAIW) in the South Atlantic Ocean has experienced basin-scaled freshening from 2005 to 2014, reflected by the Argo gridded products. Two zonal sections of WOCE observation also revealed a similar quasi-decadal signal. Our analysis revealed that such freshening was induced by the contemporaneous freshwater input in the AAIW ventilation region and the reduced more saline water carried by Agulhas Leakage.

Description: Changes in extreme regional sea level under global warming S.-E. Brunnabend, H. A. Dijkstra, M. A. Kliphuis, H. E. Bal, F. Seinstra, B. van Werkhoven, J. Maassen, and M. van Meersbergen Ocean Sci. Discuss., doi:10.5194/os-2016-57,2016 Manuscript under review for OS (discussion: open, 0 comments) An important contribution to future changes in regional sea level extremes is due to the changes in intrinsic ocean variability, in particular ocean eddies. Here, we study a scenario of future dynamic sea level (DSL) extremes using a strongly eddying version of the Parallel Ocean Program. Changes in 10-year return time DSL extremes are very inhomogeneous over the globe and are related to changes in ocean currents and corresponding regional shifts in ocean eddy pathways.

Description: Greenland annual accumulation along the EGIG line, 1959–2004, from ASIRAS airborne radar and neutron-probe density measurements Thomas B. Overly, Robert L. Hawley, Veit Helm, Elizabeth M. Morris, and Rohan N. Chaudhary The Cryosphere, 10, 1679-1694, doi:10.5194/tc-10-1679-2016, 2016 We demonstrate that snow accumulation rates across the Greenland Ice Sheet, determined from RADAR layers and modeled snow density profiles, are identical to ground-based measurements of snow accumulation. Three regional climate models underestimate snow accumulation compared to RADAR layer estimates. Using RADAR increases spatial coverage and improves accuracy of snow accumulation estimates. Incorporating our results into climate models may reduce uncertainty of sea-level rise estimates.

Description: A stable Faroe Bank Channel overflow 1995–2015 Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, and Svein Østerhus Ocean Sci. Discuss., doi:10.5194/os-2016-56,2016 Manuscript under review for OS (discussion: open, 0 comments) The Faroe Bank Channel is one of the main passages for the flow of cold dense water from the Arctic into the depths of the World Ocean where it feeds the deep branch of the AMOC transporting heat and carbon dioxide from the atmosphere into the deep ocean. Based on in situ measurements we show that the volume transport of this flow has been stable from 1995 to 2015. The water has warmed, but has not become less dense. Thus, this branch of the AMOC did not weaken during the last two decades.

Description: Thermal impacts of engineering activities and vegetation layer on permafrost in different alpine ecosystems of the Qinghai–Tibet Plateau, China Qingbai Wu, Zhongqiong Zhang, Siru Gao, and Wei Ma The Cryosphere, 10, 1695-1706, doi:10.5194/tc-10-1695-2016, 2016 Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet highway and railway, the changes of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role among engineering construction effects on permafrost beneath embankments. As before railway construction, the artificial permafrost table (APT) beneath embankments is not only affected by climate change and engineering activities but is also controlled by alpine ecosystems. However, the change rate of APT is not dependent on ecosystem type, which is predominantly affected by climate change and engineering activities. Instead, the rate is mainly related to cooling effects of railway ballast and heat absorption effects of asphalt pavement. No large difference between alpine and steppe can be identified regarding the variation of soil temperature beneath embankments, but this difference is readily identified in the variation of mean annual soil temperature with depth. The vegetation layer in alpine meadows has an insulation role among engineering activity effects on permafrost beneath embankments, but this insulation gradually disappears because the layer decays and compresses over time. On the whole, this layer is advantageous for alleviating permafrost temperature rise in the short term, but its effect gradually weakens in the long term.

Description: Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet of the Greenland Ice Sheet give in sight on sub glacial conditions Joseph Graly, Joel Harrington, and Neil Humphrey The Cryosphere Discuss., doi:10.5194/tc-2016-137,2016 Manuscript under review for TC (discussion: open, 0 comments) At a major outlet of the Greenland Ice Sheet in West Greenland, we find that the chemical solutes is the emerging subglacial waters are out of phase with water discharge and can spike in concentration during waning flow. This suggests that the subglacial waters are spreading out across a large area of the glacial bed throughout the day, stimulating chemical weathering beyond the major water distribution channels.

Description: Impact of Icebergs on Net Primary Productivity in the Southern Ocean Shuang-Ye Wu and Shugui Hou The Cryosphere Discuss., doi:10.5194/tc-2016-166,2016 Manuscript under review for TC (discussion: open, 0 comments) The primary productivity in the Southern Ocean (SO) is limited by the amount of iron available for biological activities. Recent studies show that icebergs could be a main source of iron to the SO. Based on remote sensing data, our study shows that iceberg presence has a small, yet statistically significant, positive impact on productivity. As iceberg quantity increases, their positive influence on productivity also increases. This impact could serve as a negative feedback to the climate system.

Description: Possible groundwater dominance in the subglacial hydrology of ice sheet interiors: example at Dome C, East Antarctica Brad T. Gooch, Sasha P. Carter, Omar Ghattas, Duncan A. Young, and Donald D. Blankenship The Cryosphere Discuss., doi:10.5194/tc-2016-141,2016 Manuscript under review for TC (discussion: open, 0 comments) Our work investigates the potential significance of groundwater flow underneath the interior of East Antarctica where the ice doesn't rapidly melt. We attempt to describe the relationship between two hydrologic systems (water under the ice and in the ground) and how they might interact along a flow path between lakes under the ice. We find that groundwater is significant in regional water transport for melt water under the ice in areas of low melting in East Antarctica.

Description: Design of a scanning laser meter for monitoring the spatio-temporal evolution of snow depth and its application in the Alps and in Antarctica Ghislain Picard, Laurent Arnaud, Jean-Michel Panel, and Samuel Morin The Cryosphere, 10, 1495-1511, doi:10.5194/tc-10-1495-2016, 2016 A cost-effective automatic laser scan has been built to measure snow depth spatio-temporal variations. Deployed in the Alps and in Dome C (Antarctica), two devices acquired daily scans covering a surface area of 100–150 m 2 . The precision and long-term stability of the measurements are about 1 cm and the accuracy is better than 5 cm. These high performances are particularly suited at Dome C, where it was possible to reveal that most of the accumulation in the year 2015 stems from a single event.

Description: An ice-sheet-wide framework for englacial attenuation from ice-penetrating radar data T. M. Jordan, J. L. Bamber, C. N. Williams, J. D. Paden, M. J. Siegert, P. Huybrechts, O. Gagliardini, and F. Gillet-Chaulet The Cryosphere, 10, 1547-1570, doi:10.5194/tc-10-1547-2016, 2016 Ice penetrating radar enables determination of the basal properties of ice sheets. Existing algorithms assume stationarity in the attenuation rate, which is not justifiable at an ice sheet scale. We introduce the first ice-sheet-wide algorithm for radar attenuation that incorporates spatial variability, using the temperature field from a numerical model as an initial guess. The study is a step toward ice-sheet-wide data products for basal properties and evaluation of model temperature fields.

Description: Snowpack modelling in the Pyrenees driven by kilometric-resolution meteorological forecasts Louis Quéno, Vincent Vionnet, Ingrid Dombrowski-Etchevers, Matthieu Lafaysse, Marie Dumont, and Fatima Karbou The Cryosphere, 10, 1571-1589, doi:10.5194/tc-10-1571-2016, 2016 Simulations are carried out in the Pyrenees with the snowpack model Crocus, driven by meteorological forecasts from the model AROME at kilometer resolution. The evaluation is done with ground-based measurements, satellite data and reference simulations. Studying daily snow depth variations allows to separate different physical processes affecting the snowpack. We show the benefits of AROME kilometric resolution and dynamical behavior in terms of snowpack spatial variability in a mountain range.

Description: Accessing diverse data comprehensively – CODM, the COSYNA data portal Gisbert Breitbach, Hajo Krasemann, Daniel Behr, Steffen Beringer, Uwe Lange, Nhan Vo, and Friedhelm Schroeder Ocean Sci., 12, 909-923, doi:10.5194/os-12-909-2016, 2016 The coastal observation system COSYNA aims to describe the physical and biogeochemical state of a regional coastal system. The COSYNA data management (CODM) is the link between observations, model results and data usage. The challenge for CODM is the integration of diverse data sources in terms of parameters, dimensionality and observation methods to gain a comprehensive view of the observations. How this is achieved is described in the paper.

Description: Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009 Abdirahman M. Omar, Ingunn Skjelvan, Svein Rune Erga, and Are Olsen Ocean Sci., 12, 937-951, doi:10.5194/os-12-937-2016, 2016 We have determined, for the first time, the seasonal changes and controlling processes of ocean acidification parameters across western Norwegian fjords, based on data obtained mainly with sensors on board a commercial ship, MS Trans Carrier , in 2005–2009. The study fills an important gap in our knowledge on ocean acidification in western Norwegian fjords, which are important ecosystems: important recreation areas, marine pathways, spawning grounds for different fish species, etc.

Description: Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica Benjamin E. Smith, Noel Gourmelen, Alexander Huth, and Ian Joughin The Cryosphere Discuss., doi:10.5194/tc-2016-180,2016 Manuscript under review for TC (discussion: open, 0 comments) In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the main sources of excess ice discharge into the ocean. We find that in early 2013, four subglacial lakes separated by 100 km drained suddenly, discharging more than three cubic kilometers of water under the fastest part of the glacier in less than six months. Concurrent ice-speed measurements show only minor changes, suggesting that ice dynamics are not strongly sensitive to changes in water flow.

Description: Isotopic exchange on the diurnal scale between near-surface snow and lower atmospheric water vapor at Kohnen station, East Antarctica François Ritter, Hans Christian Steen-Larsen, Martin Werner, Valérie Masson-Delmotte, Anais Orsi, Melanie Behrens, Gerit Birnbaum, Johannes Freitag, Camille Risi, and Sepp Kipfstuhl The Cryosphere, 10, 1647-1663, doi:10.5194/tc-10-1647-2016, 2016 We present the first successful continuous measurements of water vapor isotopes performed in Antarctica in January 2013. The interest is to understand the impact of the water vapor isotopic composition on the near-surface snow isotopes. Our study reveals a diurnal cycle in the snow isotopic composition in phase with the vapor. This finding suggests fractionation during the sublimation of the ice, which has an important consequence on the interpretation of water isotope variations in ice cores.

Description: An automated methodology for differentiating rock from snow, clouds and sea in Antarctica from Landsat 8 imagery: a new rock outcrop map and area estimation for the entire Antarctic continent Alex Burton-Johnson, Martin Black, Peter T. Fretwell, and Joseph Kaluza-Gilbert The Cryosphere, 10, 1665-1677, doi:10.5194/tc-10-1665-2016, 2016 We present a new rock outcrop map for the entire Antarctic continent, a principal base dataset for research and mapping in Antarctica with broad applications. To derive the map, a new methodology was developed and applied to allow automated identification of rock outcrops from Landsat 8 satellite images whilst excluding sunlit and shaded snow, clouds and liquid water – the first such automated methodology. The new dataset reveals that exposed rock forms only 0.18 % of the entire continent.

Description: Evaposublimation from the snow in the Mediterranean mountains of Sierra Nevada (Spain) Javier Herrero and María José Polo The Cryosphere Discuss., doi:10.5194/tc-2016-161,2016 Manuscript under review for TC (discussion: open, 0 comments) This manuscript presents 7 years of field work and modelling to assess the importance of the loss of water from the snow by means of sublimation in the Mediterranean mountains of Sierra Nevada. The actual sublimation rates were detected through detailed measurement of the mass fluxes from the snow. These data have led to some improvements in the modelling of the snow in this kind of mountainous semiarid regions. The sublimation is estimated to range between 24–33 % of total annual snowfall.

Description: Signature of Arctic first-year ice melt pond fraction in X-band SAR imagery Ane S. Fors, Dmitry V. Divine, Anthony P. Doulgeris, Angelika H. H. Renner, and Sebastian Gerland The Cryosphere Discuss., doi:10.5194/tc-2016-125,2016 Manuscript under review for TC (discussion: open, 0 comments) This paper investigates the signature of melt ponds in satellite borne synthetic aperture radar (SAR) imagery. The study shows that polarimetric X-band SAR can be used to extract melt pond fraction from drifting first-year sea ice, and discusses the influence of factors like wind speed, SAR incidence angle and instrument noise floor. Melt ponds strongly influence the Arctic sea ice energy budget, and the results imply prospective opportunities for expanded monitoring of melt ponds from space.

Description: Diagnosing the decline in climatic mass balance of glaciers in Svalbard over 1957–2014 Torbjørn Ims Østby, Thomas Vikhamar Schuler, Jon Ove Hagen, Regine Hock, Jack Kohler, and Carleen H. Reijmer The Cryosphere Discuss., doi:10.5194/tc-2016-172,2016 Manuscript under review for TC (discussion: open, 0 comments) We present modeled climatic mass balance for all glaciers in Svalbard for the period 1957–2014 at 1 km resolution using a coupled surface energy balance and snowpack model, thereby closing temporal and spatial gaps in direct and geodetic mass balance estimates. Supporting previous studies, our results indicate increased mass loss over the period. A detailed analysis of the involved energy fluxes reveals that increased mass loss is caused by atmospheric warming further amplified by feedbacks.

Description: Simulating ice layer formation under the presence of preferential flow in layered snowpacks Nander Wever, Sebastian Würzer, Charles Fierz, and Michael Lehning The Cryosphere Discuss., doi:10.5194/tc-2016-185,2016 Manuscript under review for TC (discussion: open, 0 comments) The study presents a dual domain approach to simulate liquid water flow in snow using the 1-dimensional physics based snow cover model SNOWPACK. In this approach, the pore space is separated into a part for matrix flow and a part that represents preferential flow. Using this approach, water can percolate sub-freezing snow and form dense (ice) layers. A comparison with snow pits shows that some of the observed ice layers were reproduced by the model while others remain challenging to simulate.

Description: Technical note: GODESS – a profiling mooring in the Gotland Basin Ralf D. Prien and Detlef E. Schulz-Bull Ocean Sci., 12, 899-907, doi:10.5194/os-12-899-2016, 2016 A profiling mooring with an interdisciplinary suite of sensors for water depths up to 300 m is described in this note. It can be programmed to take profiles through the water column at set times or intervals and with the standard set of batteries is able to profile about 34 km in total (e.g. 200 profiles of 170 m profiling each). The mooring was designed to observe the dynamics of the redoxcline in the Gotland Basin over periods of up to 3 months.

Description: Sub-basin scale sea level budgets from satellite altimetry, Argo floats and satellite gravimetry in the North Atlantic Marcel Kleinherenbrink, Riccardo Riva, and Yu Sun Ocean Sci. Discuss., doi:10.5194/os-2016-50,2016 Manuscript under review for OS (discussion: open, 0 comments) Satellite altimetry measures changes in sea level, while satellite gravimetry measures mass changes and from Argo temperature and salinity profiles one can infer steric sea level. For the first time it is shown that the mass and steric components match in most cases the total sea level measured by altimetry on a sub-basin scale in terms of trend, annual amplitude and interannual variability. We also find that the choice of gravity field filter is essential to close the budget.

Description: Marine ice sheet model performance depends on basal sliding physics and sub-shelf melting Rupert Michael Gladstone, Roland Charles Warner, Benjamin Keith Galton-Fenzi, Olivier Gagliardini, Thomas Zwinger, and Ralf Greve The Cryosphere Discuss., doi:10.5194/tc-2016-149,2016 Manuscript under review for TC (discussion: open, 0 comments) Computer models are used to simulate the behaviour of glaciers and ice sheets. It has been found that such models are required to be run at very high resolution (which means high computational expense) in order to accurately represent the evolution of marine ice sheets (ice sheets resting on bedrock below sea level), in certain situations.

Description: Effects of Seasonal Snow Cover on Hydrothermal Conditions of the Active Layer in the Northeastern Qinghai-Tibet Plateau Ji Chen, Yu Sheng, Qingbai Wu, Lin Zhao, Jing Li, and Jingyi Zhao The Cryosphere Discuss., doi:10.5194/tc-2016-134,2016 Manuscript under review for TC (discussion: open, 0 comments) The extreme thin and short-time snow cover in the northeastern Qinghai-Tibet plateau is predominantly during spring and autumn. Removal of seasonal snow cover is beneficial for cooling the active layer in the first few years. Seasonal snow cover maintains the high water content of the active layer because of the inhibitory action of snow cover on the evaporation capacity in the natural site during the daytime and in summer. Snow removal can therefore lead to a rapid decrease of soil moisture.

Description: Surface mass balance and water stable isotopes derived from firn cores on three ice rises, Fimbul Ice Shelf, Antarctica Carmen P. Vega, Elisabeth Schlosser, Dmitry V. Divine, Jack Kohler, Tõnu Martma, Anja Eichler, Margit Schwikowski, and Elisabeth Isaksson The Cryosphere Discuss., doi:10.5194/tc-2016-164,2016 Manuscript under review for TC (discussion: open, 0 comments) Surface mass balance and water stable isotopes from firn cores on three ice rises at Fimbul Ice Shelf, are reported. The results suggest that the ice rises are suitable sites for the retrieval of longer firn and ice cores. The first deuterium excess data for the area suggests a possible role of seasonal moisture transport changes on the annual isotopic signal. Large-scale atmospheric circulation patterns most likely provide the dominant influence on water stable isotope ratios at the sites.

Description: Seiche excitation in a highly stratified fjord of southern Chile: the Reloncaví fjord Manuel I. Castillo, Oscar Pizarro, Nadin Ramirez, and Mario Caceres Ocean Sci. Discuss., doi:10.5194/os-2016-42,2016 Manuscript under review for OS (discussion: open, 0 comments) Here we present the results of an intensive physical oceanography study on the Reloncavi fjord (41.5º S, 72.5º W) focused on the subinertial time-scale. The along-fjord currents presented 3 days oscillations which were consistent with the natural internal period of oscillation of the fjord basin (internal seiche). This oscillation could exexplain more than 44 % of the 3 days variability and contributed levels of kinetic energy as large as the tidal currents.

Description: Evaluation of Peaks-Over-Threshold Method Soheil Saeed Far and Ahmad Khairi Abd. Wahab Ocean Sci. Discuss., doi:10.5194/os-2016-47,2016 Manuscript under review for OS (discussion: open, 0 comments) In this paper, two commonly used extreme value analysis models have been developed (POT and GPD models). Both models use threshold values to censor a range of data. The results of this study show the two models are very sensitive to any changes in threshold value. Moreover, the POT model has shown some imperfections in determining true threshold value and a best fitting distribution function. Two methods were proposed by this paper to deal with the limitations in order to improve the model.

Description: Reflective properties of white and snow-covered sea ice Aleksey Malinka, Eleonora Zege, Georg Heygster, and Larysa Istomina The Cryosphere Discuss., doi:10.5194/tc-2016-153,2016 Manuscript under review for TC (discussion: open, 0 comments) The amount of melt ponds on Arctic summer sea ice and its reflectance are required for better climate modelling and weather prediction. In order to derive these quantities from optical satellite observations, simple analytical formulas for the bidirectional reflectance factor and albedo at direct and diffuse incidence are derived from basic assumptions and verified with in situ measurements made during the expedition ARK-XXVII/3 of research vessel Polarstern in 2012.

Description: Application and validation of long-range terrestrial laser scanning to monitor the mass balance of very small glaciers in the Swiss Alps Mauro Fischer, Matthias Huss, Mario Kummert, and Martin Hoelzle The Cryosphere, 10, 1279-1295, doi:10.5194/tc-10-1279-2016, 2016 This study provides the first thorough validation of geodetic glacier mass changes derived from close-range high-resolution remote sensing techniques, and highlights the potential of terrestrial laser scanning for repeated mass balance monitoring of very small alpine glaciers. The presented methodology is promising, as laborious and potentially dangerous in situ measurements as well as the spatial inter- and extrapolation of point measurements over the entire glacier can be circumvented.

Description: Greenland Ice Sheet seasonal and spatial mass variability from model simulations and GRACE (2003–2012) Patrick M. Alexander, Marco Tedesco, Nicole-Jeanne Schlegel, Scott B. Luthcke, Xavier Fettweis, and Eric Larour The Cryosphere, 10, 1259-1277, doi:10.5194/tc-10-1259-2016, 2016 We compared satellite-derived estimates of spatial and seasonal variations in Greenland Ice Sheet mass with a set of model simulations, revealing an agreement between models and satellite estimates for the ice-sheet-wide seasonal fluctuations in mass, but disagreement at finer spatial scales. The model simulations underestimate low-elevation mass loss. Improving the ability of models to capture variations and trends in Greenland Ice Sheet mass is important for estimating future sea level rise.

Description: Development and calibration of an automatic spectral albedometer to estimate near-surface snow SSA time series Ghislain Picard, Quentin Libois, Laurent Arnaud, Gauthier Verin, and Marie Dumont The Cryosphere, 10, 1297-1316, doi:10.5194/tc-10-1297-2016, 2016 Albedo of snow surfaces depends on snow grain size. By measuring albedo during 3 years at Dome C in Antarctica with an automatic spectroradiometer, we were able to monitor the snow specific surface area and show an overall growth of the grains in spring and summer followed by an accumulation of small-grained snow from mid-summer. This study focuses on the uncertainties due to the spectroradiometer and concludes that the observed variations are significant with respect to the precision.

Description: The importance of external climate forcing for the variability and trends of coastal upwelling in past and future climate Nele Tim, Eduardo Zorita, Birgit Hünicke, Xing Yi, and Kay-Christian Emeis Ocean Sci., 12, 807-823, doi:10.5194/os-12-807-2016, 2016 The impact of external climate forcing on the four eastern boundary upwelling systems is investigated for the recent past and future. Under increased radiative forcing, upwelling-favourable winds should strengthen due to unequal heating of land and oceans. However, coastal upwelling simulated in ensembles of climate simulations do not show any imprint of external forcing neither for the past millennium nor for the future, with the exception of the strongest future scenario.

Description: Which are the highest peaks in the US Arctic? Fodar settles the debate Matt Nolan and Kit DesLauriers The Cryosphere, 10, 1245-1257, doi:10.5194/tc-10-1245-2016, 2016 We measured the heights of the five tallest peaks in the US Arctic using fodar, a new airborne photogrammetric technique using structure-from-motion software. The highest peaks are Mt Isto (2735.6 m), Mt. Hubley (2717.6 m), Mt. Chamberlin (2712.3 m), Mt. Michelson (2698.1 m), and an unnamed peak (2694.9 m). We found fodar suitable for topographic change detection on the centimeter scale in steep mountain terrain, such as for measuring snow depths.

Description: Three-year monitoring of stable isotopes of precipitation at Concordia Station, East Antarctica Barbara Stenni, Claudio Scarchilli, Valerie Masson-Delmotte, Elisabeth Schlosser, Virginia Ciardini, Giuliano Dreossi, Paolo Grigioni, Mattia Bonazza, Anselmo Cagnati, Daniele Karlicek, Camille Risi, Roberto Udisti, and Mauro Valt The Cryosphere Discuss., doi:10.5194/tc-2016-142,2016 Manuscript under review for TC (discussion: open, 0 comments) Here, we focus on the Concordia Station, central East Antarctic plateau, providing a multi-year record (2008–2010) of daily precipitation types identified from crystal morphologies, precipitation amounts, and isotopic composition. Relationships between local meteorological data and precipitation oxygen isotope composition are investigated. Our dataset is available for in depth model evaluation at the synoptic scale.

Description: Development and analysis of a continuous record of global near-surface soil freeze/thaw patterns from AMSR-E and AMSR2 data Tongxi Hu, Tianjie Zhao, Jiancheng Shi, Tianxing Wang, Dabin Ji, Ahmad Al Bitar, Bin Peng, and Yurong Cui The Cryosphere Discuss., doi:10.5194/tc-2016-115,2016 Manuscript under review for TC (discussion: open, 0 comments) We present an approach of satellite remote sensing to derive a continuous long term and stable data record of the near-surface freeze/thaw cycle over the permafrost and seasonally frozen ground. We find that the distribution of the frost days and its trend variations are consistent with the minimum temperature anomalies. Analysis over the Qinghai-Tibetan Plateau demonstrates that the frost period is shortening slightly over the past decade, and the last frost date is advanced in most regions.

Description: Operational algorithm for ice/water classification on dual-polarized RADARSAT-2 images Natalia Zakhvatkina, Anton Korosov, Stefan Muckenhuber, Stein Sandven, and Mohamed Babiker The Cryosphere Discuss., doi:10.5194/tc-2016-131,2016 Manuscript under review for TC (discussion: open, 0 comments) The presented fully automated algorithm distinguishes open water (rough/calm) and sea ice based on dual-polarized RS2 SAR images. Texture features are used for Support Vector Machines supervised image classification. The algorithm includes pre-processing and validation procedures. More than 2700 scenes were processed and the results show the good discrimination between open water and sea ice areas with accuracy 91 % compared with ice charts produced by MET Norway service.

Description: Marine mammal tracks from two-hydrophone acoustic recordings made with a glider Elizabeth T. Küsel, Tessa Munoz, Martin Siderius, David K. Mellinger, and Sara Heimlich Ocean Sci. Discuss., doi:10.5194/os-2016-48,2016 Manuscript under review for OS (discussion: open, 0 comments) An ocean glider was tested during the REP14-MED experiment off the western coast of the Island of Sardinia as a platform for recording sounds produced by whales and dolphins using two sensors. Sperm whale clicks as well as dolphin clicks and whistles were identified in the recordings. Automatically detected sperm whale clicks were used to estimate animal tracks. Such information is useful for marine mammal density estimation studies that use passive acoustics.

Description: Seasonal, Spring-Neap and Tidal Variation of Hydrodynamics and Water Constituents in the Mouth of the Elbe Estuary, Germany Jens Kappenberg, Michael Berendt, Nino Ohle, Rolf Riethmüller, Dagmar Schuster, and Thomas Strotmann Ocean Sci. Discuss., doi:10.5194/os-2016-7,2016 Manuscript under review for OS (discussion: open, 0 comments) Results of long-term measurements of CTD, current velocity, turbidity, and dissolved oxygen from three stations in the mouth of the Elbe Estuary in northern Germany are presented for the period of 2012 and 2013. The focus is on a station named HPA-Elbe 1, which is part of the COSYNA coastal observing system for northern and arctic seas, but data from two neighbouring stations are also presented for comparison and to bridge gaps in the time-series of HPA-Elbe 1. The variations of the variables exhibit distinct tidal patterns related to the longitudinal estuarine gradients of the water constituents and local sediment dynamics. On longer time-scales, spring-neap variability is observed, most prominently in the hydrodynamics. On the seasonal scale, the water temperature influences the degradation processes, which deplete the dissolved oxygen on the one hand and increase the oxygen contents by biological respiration on the other hand. Freshwater events from the catchment play an important role for sediment dynamics and mixing of riverine and coastal waters in the brackish water reach of the estuary. The periods of the deployment of the stations comprise the severest river flood observed so far in the Elbe in June 2013. The effects of the flood at the stations and along the estuary consist of a rapid flushing of the mixing zone and the turbidity maximum to the outer estuary and the transition to freshwater conditions from Hamburg to the mouth at Cuxhaven. The impact of the river flood at the stations is more pronounced in changes in salinity than in turbidity. The restoration of estuarine salinity and turbidity values comparable to those before the river flood took several months.

Description: Imaging air volume fraction in sea ice using non-destructive X-ray tomography Odile Crabeck, Ryan Galley, Bruno Delille, Brent Else, Nicolas-Xavier Geilfus, Marcos Lemes, Mathieu Des Roches, Pierre Francus, Jean-Louis Tison, and Søren Rysgaard The Cryosphere, 10, 1125-1145, doi:10.5194/tc-10-1125-2016, 2016 We present a new non-destructive X-ray-computed tomography technique to quantify the air volume fraction and produce separate 3-D images of air-volume inclusions in sea ice. While the internal layers showed air-volume fractions 〈 2 %, the ice–air interface (top 2 cm) showed values up to 5 %. As a result of the presence of large bubbles and higher air volume fraction measurements in sea ice, we introduce new perspectives on processes regulating gas exchange at the ice–atmosphere interface.

Description: Monitoring the temperature dependent elastic and anelastic properties in isotropic polycrystalline ice using resonant ultrasound spectroscopy Matthew J. Vaughan, Kasper van Wilk, David J. Prior, and M. Hamish Bowman The Cryosphere Discuss., doi:10.5194/tc-2016-127,2016 Manuscript under review for TC (discussion: open, 0 comments) The physical properties of ice are of interest in the study of the dynamics of sea ice, glaciers and ice sheets. We used resonant ultrasound spectroscopy to estimate the effects of temperature on the elastic and an-elastic characteristics of polycrystalline ice, which control the propagation of sound waves. This information helps calibrate seismic data, in order to determine regional scale ice properties, improving our ability to predict ice sheet behaviour in response to climate change.

Description: Basal buoyancy and fast-moving glaciers: in defense of analytic force balance C. J. van der Veen The Cryosphere, 10, 1331-1337, doi:10.5194/tc-10-1331-2016, 2016 This paper evaluates the geometric force balance, with application to Byrd Glacier, Antarctica. It is concluded that this approach does not yield physically reasonable results.

Description: Ocean Forecasting: From Regional to Coastal Scales Emil V. Stanev, Johannes Schulz-Stellenfleth, Joanna Staneva, Sebastian Grayek, Sebastian Grashorn, Arno Behrens, Wolfgang Koch, and Johannes Pein Ocean Sci. Discuss., doi:10.5194/os-2016-25,2016 Manuscript under review for OS (discussion: open, 0 comments) This paper describes coastal ocean forecasting practices exemplified for the North and Baltic Sea. It identifies new challenges, most of which are associated with the non-linear behavior of coastal ocean. It describes assimilation of remote sensing, in situ and HF radar data, prediction of wind waves and storm surges, as well as possible applications to search and rescue operations, and modelling support for assessing the environmental impact of wind parks. Concepts for seamless approaches to li

Description: A possibility of large scale intrusions generation in the Arctic Ocean under stable-stable stratification: an analytical consideration Natalia Kuzmina Ocean Sci. Discuss., doi:10.5194/os-2016-15,2016 Manuscript under review for OS (discussion: open, 0 comments) Some analytical solutions are found for the problem of three-dimensional instability of a weak geostrophic flow with linear velocity shear taking into account vertical diffusion of buoyancy. The analysis is based on the potential vorticity equation in a long-wave approximation when the horizontal scale of disturbances is taken to be much larger than the local baroclinic Rossby radius. It is hypothesized that the solutions found can be applied to describe stable and unstable disturbances on a planetary scale with respect, especially, to the Arctic Basin, where weak baroclinic fronts with typical temporal variability periods of the order of several years or more are observed and the beta-effect is negligible. Stable (decaying with time) solutions describe disturbances that, in contrast to the Rossby waves, can propagate to both the west and east, depending on the sign of the linear shear of geostrophic velocity. The unstable (growing with time) solutions are applied to describe large-scale intrusions at baroclinic fronts under the stable–stable thermohaline stratification observed in the upper layer of the Polar Deep Water in the Eurasian Basin. The proposed description of intrusive layering can be considered as a possible alternative to the mechanism of interleaving due to the differential mixing.

Description: Assessment of Arctic and Antarctic Sea Ice Predictability in CMIP5 Decadal Hindcasts Chao-Yuan Yang, Jiping Liu, Yongyun Hu, Radley M. Horton, Liqi Chen, and Xiao Cheng The Cryosphere Discuss., doi:10.5194/tc-2016-97,2016 Manuscript under review for TC (discussion: open, 0 comments) This paper examines the ability of coupled global climate models to predict decadal variability of Arctic and Antarctic sea ice. We analyze decadal hindcasts/predictions of 11 CMIP5 models. Decadal hindcasts exhibit a large multi-model spread in the simulated sea ice extent, with some models deviating significantly from the observations. For the models having large biases and using full-field initialization, the predicted sea ice extent quickly drifts away from the initial constraint, deteriorating the decadal predictive skill. The anomaly correlation analysis between the decadal hindcast and observed sea ice suggests that in the Arctic, for most models, the areas showing significant predictive skill become broader associated with increasing lead times. This area expansion is largely because nearly all the models are capable of predicting the observed decreasing Arctic sea ice cover. Sea ice extent in the north Pacific has better predictive skill than that in the north Atlantic (particularly at a lead-time of 3–7 years), but there is a re-emerging predictive skill in the north Atlantic at a lead-time of 6–8 years. In contrast to the Arctic, Antarctic sea ice decadal hindcasts do not show broad predictive skill at any time scales, and there is no obvious improvement linking the areal extent of significant predictive skill to lead-time increase. This might be because nearly all the models predict a retreating Antarctic sea ice cover, opposite to the observations. For the Arctic, the predictive skill of the MMEE outperforms most models and the persistence prediction at longer time scales, which is not the case for the Antarctic.

Description: On the recent contribution of the Greenland ice sheet to sea level change Michiel van den Broeke, Ellyn Enderlin, Ian Howat, Peter Kuipers Munneke, Brice Noël, Willem Jan van de Berg, Erik van Meijgaard, and Bert Wouters The Cryosphere Discuss., doi:10.5194/tc-2016-123,2016 Manuscript under review for TC (discussion: open, 0 comments) We present recent (1958–2015) mass balance time series for the Greenland ice sheet. We show that recent mass loss is caused by a combination of increased surface meltwater runoff and solid ice discharge. Most meltwater above 2000 m a.s.l. refreezes in the cold firn and does not leave the ice sheet, but this goes at the expense of firn heating and densifying. In spite of a temporary rebound in 2013, it appears that the ice sheet remains in a state of persistent mass loss

Description: Reconstructing the mass balance of Brewster Glacier, New Zealand, using MODIS-derived glacier-wide albedo Pascal Sirguey, Holly Still, Nicolas J. Cullen, Marie Dumont, Yves Arnaud, and Jonathan P. Conway The Cryosphere Discuss., doi:10.5194/tc-2016-98,2016 Manuscript under review for TC (discussion: open, 0 comments) 14 years of satellite observations are used to monitor the albedo of Brewster Glacier, New Zealand and estimate annual and seasonal balances. This confirms the governing role of the summer balance in the annual balance and allows the reconstruction of the annual balance back to 1977 using a photographic record of the snowline. The longest mass balance record for a New Zealand glacier shows that negative balances after 2008 yielded a loss of 35 % of the gain accumulated over the previous 30 years.

Description: Modeling debris-covered glaciers: response to steady debris deposition Leif S. Anderson and Robert S. Anderson The Cryosphere, 10, 1105-1124, doi:10.5194/tc-10-1105-2016, 2016 Mountains erode and shed rocks down slope. When these rocks (debris) fall on glacier ice they can suppress ice melt. By protecting glaciers from melt, debris can make glaciers extend to lower elevations. Using mathematical models of glaciers and debris deposition, we find that debris can more than double the length of glaciers. The amount of debris deposited on the glacier, which scales with mountain height and steepness, is the most important control on debris-covered glacier length and volume.

Description: Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach Kristof Van Tricht, Stef Lhermitte, Irina V. Gorodetskaya, and Nicole P. M. van Lipzig The Cryosphere Discuss., doi:10.5194/tc-2016-103,2016 Manuscript under review for TC (discussion: open, 0 comments) Despite the crucial role of polar regions in the global climate system, the limited availability of observations on the ground hampers a detailed understanding of their energy budget. Here we develop a method to use satellites to fill these observational gaps. We show that by sampling satellite observations in a smart way, coverage is greatly enhanced. We conclude that this method might help improving our understanding of the polar energy budget, and ultimately its effects in the global climate.

Description: Impacts of marine instability across the East Antarctic Ice Sheet on Southern Ocean dynamics Steven J. Phipps, Christopher J. Fogwill, and Christian S. M. Turney The Cryosphere Discuss., doi:10.5194/tc-2016-111,2016 Manuscript under review for TC (discussion: open, 0 comments) We explore the effects of melting of the East Antarctic Ice Sheet on the Southern Ocean. Using a climate model, we find that melting changes the ocean circulation and causes warming of more than 1 ºC at depth. We also discover the potential existence of a "domino effect", whereby the initial warming spreads westwards around the Antarctic continent. Melting of just one sector could therefore destabilise the wider Antarctic Ice Sheet, leading to substantial increases in global sea level.

Description: Multi-sensor in situ observations to resolve the sub-mesoscale features in the stratified Gulf of Finland, Baltic Sea Urmas Lips, Villu Kikas, Taavi Liblik, and Inga Lips Ocean Sci., 12, 715-732, doi:10.5194/os-12-715-2016, 2016 Multi-platform high-resolution observations in the Gulf of Finland in the summers of 2009–2012 revealed pronounced variability at the sub-mesoscale in the presence of mesoscale features, such as upwelling/downwelling events, fronts, and eddies. The analysis suggests that the sub-mesoscale processes could contribute considerably to the downscale energy cascade and play a major role in phytoplankton growth enhancement via vertical transport and re-stratification of the surface layer.

Description: Mechanism of Seasonal Arctic Sea Ice Evolution and Arctic Amplification Kwang-Yul Kim, Benjamin D. Hamlington, Hanna Na, and Jinju Kim The Cryosphere Discuss., doi:10.5194/tc-2016-69,2016 Manuscript under review for TC (discussion: open, 0 comments) Analysis reveals that "Arctic Amplification", lower tropospheric winter temperature rise in the Arctic, is due to sea ice melting and the resulting increase in the amount of turbulent heat flux from the ocean. As a result of increased turbulent heat flux, lower atmosphere warms up, resulting in increased downward longwave radiation. A detailed physical mechanism is presented together with an explanation why this positive feedback process is currently possible in the Barents-Kara Seas.

Description: Glacier melting and precipitation trends detected by surface area changes in Himalayan ponds Franco Salerno, Sudeep Thakuri, Nicolas Guyennon, Gaetano Viviano, and Gianni Tartari The Cryosphere Discuss., doi:10.5194/tc-2016-39,2016 Manuscript under review for TC (discussion: open, 0 comments) This contribution shows that the surface area variations of unconnected glacial ponds, i.e., ponds not directly connected to glaciers, can be considered suitable proxies for detecting changes in the main hydrological components of the water balance on the south side of Mt. Everest.

Description: Glacier melting and precipitation trends detected by surface area changes in Himalayan ponds Franco Salerno, Sudeep Thakuri, Nicolas Guyennon, Gaetano Viviano, and Gianni Tartari The Cryosphere, 10, 1433-1448, doi:10.5194/tc-10-1433-2016, 2016 This contribution shows that the surface area variations of unconnected glacial ponds, i.e. ponds not directly connected to glacier ice, can be considered as suitable proxies for detecting past changes in the main hydrological components of the water balance (glacier melt, precipitation, evaporation) on the south side of Mt Everest.

Description: Strain localisation and dynamic recrystallisation in the ice-air aggregate: A numerical study Florian Steinbach, Paul D. Bons, Albert Griera, Daniela Jansen, Maria-Gema Llorens, Jens Roessiger, and Ilka Weikusat The Cryosphere Discuss., doi:10.5194/tc-2016-167,2016 Manuscript under review for TC (discussion: open, 0 comments) How glaciers or ice sheets flow is a result of microscopic processes controlled by the properties of individual ice crystals. We performed computer simulations on these processes and the effect of air bubbles between crystals. The simulations show that small scale ice deformation is locally stronger than in other regions, which is enhanced by bubbles. This causes the ice crystals to recrystallise and change their properties in a way that potentially also affects the large scale flow properties.

Description: Brief Communication: Twelve-year cyclic surging episodes at Donjek Glacier in Yukon, Canada Takahiro Abe, Masato Furuya, and Daiki Sakakibara The Cryosphere, 10, 1427-1432, doi:10.5194/tc-10-1427-2016, 2016 We identified 12-year cyclic surging episodes at Donjek Glacier in Yukon, Canada. The surging area is limited within the ~20km section from the terminus, originating in an area where the flow width significantly narrows downstream. Our results suggest strong control of the valley constriction on the surge dynamics.

Description: First year of the new Arctic AWIPEV-COSYNA cabled Underwater Observatory in Kongsfjorden, Spitsbergen Philipp Fischer, Max Schwanitz, Reiner Loth, Uwe Posner, Markus Brand, and Friedhelm Schröder Ocean Sci. Discuss., doi:10.5194/os-2016-52,2016 Manuscript under review for OS (discussion: open, 0 comments) We observed oceanographic and community data from October 2013 to November 2014 in the shallow waters of Kongsfjorden on the west coast of Svalbard (Norway) using remote controlled hydrographic and optic sensors. Daily vertical profiles of temperature, salinity and turbidity were sampled together with stereo images of the macrobiotic community, including fish. A distinct seasonal cycle in total species abundances was found with surprisingly high animal counts during the polar winter.

Description: Age of the Mt. Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum Paolo Gabrielli, Carlo Barbante, Giuliano Bertagna, Michele Bertó, Daniel Binder, Alberto Carton, Luca Carturan, Federico Cazorzi, Giulio Cozzi, Giancarlo Dalla Fontana, Mary Davis, Fabrizio De Blasi, Roberto Dinale, Gianfranco Dragà, Giuliano Dreossi, Daniela Festi, Massimo Frezzotti, Jacopo Gabrieli, Stephan Galos, Patrick Ginot, Petra Heidenwolf, Theo M. Jenk, Natalie Kehrwald, Donald Kenny, Olivier Magand, Volkmar Mair, Vladimir Mikhalenko, Ping Nan Lin, Klaus Oeggl, Gianni Piffer, Mirko Rinaldi, Ulrich Schotterer, Margit Schwikowski, Roberto Seppi, Andrea Spolaor, Barbara Stenni, Davdi Tonidandel, CChiara Uglietti, Victor Zagorodnov, Thomas Zanoner, and Piero Zennaro The Cryosphere Discuss., doi:10.5194/tc-2016-159,2016 Manuscript under review for TC (discussion: open, 0 comments) New ice cores were extracted from Alto dell'Ortles, the highest glacier of South Tyrol in the Italian Alps, to check whether prehistoric ice, that is coeval to the famous 5200 years old Tyrolean Iceman, is still preserved in this region. Dating of the ice cores confirms the hypothesis and indicates that the drilling site was glaciated since the end of the Northern Hemisphere Climatic Optimum (7000 BP). We also infer that an unprecedented acceleration of the glacier flow has just recently begun.

Description: Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia Pier Paul Overduin, Sebastian Wetterich, Frank Günther, Mikhail N. Grigoriev, Guido Grosse, Lutz Schirrmeister, Hans-Wolfgang Hubberten, and Aleksandr Makarov The Cryosphere, 10, 1449-1462, doi:10.5194/tc-10-1449-2016, 2016 How fast does permafrost warm up and thaw after it is covered by the sea? Ice-rich permafrost in the Laptev Sea, Siberia, is rapidly eroded by warm air and waves. We used a floating electrical technique to measure the depth of permafrost thaw below the sea, and compared it to 60 years of coastline retreat and permafrost depths from drilling 30 years ago. Thaw is rapid right after flooding of the land and slows over time. The depth of permafrost is related to how fast the coast retreats.

Description: Inversion of geothermal heat flux in a thermomechanically coupled nonlinear Stokes ice sheet model Hongyu Zhu, Noemi Petra, Georg Stadler, Tobin Isaac, Thomas J. R. Hughes, and Omar Ghattas The Cryosphere, 10, 1477-1494, doi:10.5194/tc-10-1477-2016, 2016 We study how well the basal geothermal heat flux can be inferred from surface velocity observations using a thermomechanically coupled nonlinear Stokes ice sheet model. The prospects and limitations of this inversion is studied in two and three dimensional model problems. We also argue that a one-way coupled approach for the adjoint equations motivated by staggered solvers for forward multiphysics problems can lead to an incorrect gradient and premature termination of the optimization iteration.

Description: GEM: A Dynamic Tracking Model for Mesoscale Eddies in the Ocean Qiu-Yang Li, Liang Sun, and Sheng-Fu Lin Ocean Sci. Discuss., doi:10.5194/os-2016-49,2016 Manuscript under review for OS (discussion: open, 0 comments) Genealogical Evolution Model (GEM) is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern with a two-dimensional vector. All of the computational steps are linear and do not include iteration. It is very fast and is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.

Description: Slight glacier reduction over the northwestern Tibetan Plateau despite significant recent warming Yetang Wang, Shugui Hou, Wenling An, Hongxi Pang, and Yaping Liu The Cryosphere Discuss., doi:10.5194/tc-2016-165,2016 Manuscript under review for TC (discussion: open, 0 comments) This study further confirms "Pamir–Karakoram–Western-Kunlun-Mountain (northwestern Tibetan Plateau) Glacier Anomaly". Slight glacier reduction over the northwestern Tibetan Plateau may result from more accumulation from increased precipitation in winter which to great extent protects it from mass reductions under climate warming during 1961–2000. Warming slowdown since 2000 happening at this region may further mitigate glacier mass reduction.

Description: Characteristics of an avalanche-feeding and partially debris-covered glacier and its response to atmospheric warming in Mt. Tomor, Tian Shan, China Puyu Wang, Zhongqin Li, and Huilin Li The Cryosphere Discuss., doi:10.5194/tc-2016-138,2016 Manuscript under review for TC (discussion: open, 0 comments) A cirque-valley glacier with complex topography and partially debris-covered area was investigated in the Mt. Tomor, Tian Shan. The glacier is analogous to temperate one on movement and temperature regimes. The strongest ablation and most significant terminus retreat and area reduction occurred at the end of last century and the beginning of this century. Since inhibition of debris cover to melting, it is expected to keep shrinkage in the coming decades, but the terminus retreat is to be slower.

Description: Arctic sea-ice diffusion from observed and simulated Lagrangian trajectories Pierre Rampal, Sylvain Bouillon, Jon Bergh, and Einar Ólason The Cryosphere, 10, 1513-1527, doi:10.5194/tc-10-1513-2016, 2016 Due to the increasing activity in Arctic, sea-ice–ocean models are now frequently used to produce operational forecasts, for oil spill trajectory modelling and to assist in offshore operations planning. In this study we evaluate the performance of two models with respect to their capability to reproduce observed sea ice diffusion properties by using metrics based on Lagrangian statistics. This paper presents a new and useful evaluation metric for current coupled sea ice–ocean models.

Description: Retrieval of the thickness of undeformed sea ice from simulated C-band compact polarimetric SAR images Xi Zhang, Wolfgang Dierking, Jie Zhang, Junmin Meng, and Haitao Lang The Cryosphere, 10, 1529-1545, doi:10.5194/tc-10-1529-2016, 2016 In this work, we introduced a parameter ("CP ratio") for the retrieval of the thickness of undeformed first-year sea ice that is specifically adapted to compact polarimetric SAR images. Based on a validation using other compact polarimetric SAR images from the Labrador Sea, we found a root mean square error of 8 cm and a maximum correlation coefficient of 0.94 for the retrieval procedure when applying it to level ice between 0.1 m and 0.8 m thick.

Description: High resolution boundary conditions of an old ice target near Dome C, Antarctica Duncan A. Young, Jason L. Roberts, Catherine Ritz, Massimo Frezzotti, Enrica Quartini, Marie G. P. Cavitte, Carly R. Tozer, Daniel Steinhage, Stefano Urbini, Hugh F. J. Corr, Tas Van Ommen, and Donald D. Blankenship The Cryosphere Discuss., doi:10.5194/tc-2016-169,2016 Manuscript under review for TC (discussion: open, 0 comments) Glacial ice can preserve records of Earth's ancient atmosphere (including greenhouse gases) that can be compared to ocean sediment records of ice sheet size to better understand climate feedbacks. To find records of the greenhouse gases found in key periods of climate transition, we need to find sites of unmelted old ice near the base of the ice sheet. We performed a high resolution survey of such a site near Europe's Concordia station in East Antarctica, using a multi instrument aircraft.

Description: Effects of stratified active layers on high-altitude permafrost warming: a case study on the Qinghai–Tibet Plateau Xicai Pan, Yanping Li, Qihao Yu, Xiaogang Shi, Daqing Yang, and Kurt Roth The Cryosphere, 10, 1591-1603, doi:10.5194/tc-10-1591-2016, 2016 Using a 9-year dataset in conjunction with a process-based model, we verify that the common assumption of a considerably smaller thermal conductivity in the thawed season than the frozen season is not valid at a site with a stratified active layer on the Qinghai–Tibet Plateau (QTP). The unique hydraulic and thermal mechanism in the active layer challenges the concept of thermal offset used in conceptual permafrost models and hints at the reason for rapid permafrost warming on the QTP.

Description: Observed and simulated full-depth ocean heat-content changes for 1970–2005 Lijing Cheng, Kevin E. Trenberth, Matthew D. Palmer, Jiang Zhu, and John P. Abraham Ocean Sci., 12, 925-935, doi:10.5194/os-12-925-2016, 2016 A new method of observing ocean heat content throughout the entire ocean depth is provided. The new method is compared with simulated ocean heat content changes from climate models. The comparisons are carried out in various depth layers of the ocean waters. It is found that there is excellent agreement between the models and the observations. Furthermore, we propose that changes to ocean heat content be used as a fundamental metric to evaluate climate models.

Description: Transition to El Niño conditions in the eastern tropical Pacific in October 2015 Lothar Stramma, Tim Fischer, Damian S. Grundle, Gerd Krahmann, Hermann W. Bange, and Christa A. Marandino Ocean Sci. Discuss., doi:10.5194/os-2016-14,2016 Manuscript under review for OS (discussion: open, 0 comments) Results from a research cruise on RV Sonne to the eastern tropical Pacific in October 2015 during the 2015–2016 El Niño show the transition of current, hydrographic and nutrient conditions to El Niño conditions in the eastern tropical Pacific in October 2015. Although in early 2015 the El Niño was strong and in October 2015 showed a clear El Niño influence on the EUC, in the eastern tropical Pacific the measurements only showed developing El Niño water mass distributions.

Description: Basal sliding of temperate basal ice on a rough, hard bed: pressure melting, creep mechanisms and implications for ice streaming Maarten Krabbendam The Cryosphere Discuss., doi:10.5194/tc-2016-52,2016 Manuscript under review for TC (discussion: open, 0 comments) The way that ice moves over rough ground at the base of an ice sheet is important to understand and predict the behaviour of ice sheets. Here, I argue that if basal ice is at the melting temperature, as is locally the case below the Greenland Ice Sheet, this basal motion is easier and faster than hitherto thought. A thick (10's of metres) layer of ice at the melting temperature may better explain some ice streams, and needs to be taken into account when modelling future ice sheet behaviour.

Description: Brief communication: Two well-marked cases of aerodynamic adjustment of sastrugi C. Amory, F. Naaim-Bouvet, H. Gallée, and E. Vignon The Cryosphere, 10, 743-750, doi:10.5194/tc-10-743-2016, 2016 This study presents observational characterization of interactions between wind-induced surface roughness and aeolian erosion over a rough surface in coastal East Antarctica. It is shown that the drag caused by small-scale roughness elements can significantly affects the aeolian snow mass flux during an erosion event, depending on the ability of the surface to adjust according to the main wind. Such measurements are essential to improve parameterization schemes for aeolian snow transport models.

Description: Wind changes above warm Agulhas Current eddies M. Rouault, P. Verley, and B. Backeberg Ocean Sci., 12, 495-506, doi:10.5194/os-12-495-2016, 2016 Our study shows that wind increases of 4 to 8 m s −1 above warm Agulhas Current eddies are not uncommon. This should be taken seriously when sailing in the “Roaring Forties”. Using microwave remote sensing from satellite is a very useful tool for monitoring such eddies. This could be displayed operationally to provide vessels with early warning and to indicate where there are likely to sustain stronger wind. The result is also relevant for the Gulf Stream and the Kuroshio Current.

Description: Brief communication: The challenge and benefit of using sea ice concentration satellite data products with uncertainty estimates in summer sea ice data assimilation Qinghua Yang, Martin Losch, Svetlana N. Losa, Thomas Jung, Lars Nerger, and Thomas Lavergne The Cryosphere, 10, 761-774, doi:10.5194/tc-10-761-2016, 2016 We assimilate the summer SICCI sea ice concentration data with an ensemble-based Kalman Filter. Comparing with the approach using a constant data uncertainty, the sea ice concentration estimates are further improved when the SICCI-provided uncertainty are taken into account, but the sea ice thickness cannot be improved. We find the data assimilation system cannot give a reasonable ensemble spread of sea ice concentration and thickness if the provided uncertainty are directly used.

Description: On retrieving sea ice freeboard from ICESat laser altimeter Kirill Khvorostovsky and Pierre Rampal The Cryosphere Discuss., doi:10.5194/tc-2016-50,2016 Manuscript under review for TC (discussion: open, 0 comments) We analyse two methods of freeboard retrieval from ICESat satellite data that were used to derived the two widely used Arctic sea ice thickness products. We show that although different factors results in significant local differences between freeboards, they are roughly compensating each other with respect to overall freeboard estimation. Thus the difference found between the sea ice thickness datasets should be attributed to different parameters used in the freeboard-to-thickness conversion.

Description: Stable isotopic evidence for high microbial nitrate throughput in a High Arctic glacial catchment A. H. Ansari The Cryosphere Discuss., doi:10.5194/tc-2016-59,2016 Manuscript under review for TC (discussion: open, 0 comments) The solute chemistry and stable isotope investigation of the snowpack and stream samples demonstrates a large scale microbial NO 3 − -N production (1.64 ± 1.41 kg Day −1 for MLE and 1.41 ± 1.43 kg Day −1 for MLW) and assimilation (1.39 ± 1.41 kg Day −1 for MLE and 1.35 ± 1.43 kg Day −1 for MLW) in the glacier catchment. The microbial nitrate production and consumption are several times higher than the actual nitrate flux of streams therefore infer that microbes play a much greater role in the glacial nitrogen.

Description: Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts Ursula Weiser, Marc Olefs, Wolfgang Schöner, Gernot Weyss, and Bernhard Hynek The Cryosphere, 10, 775-790, doi:10.5194/tc-10-775-2016, 2016 Geometric effects induced by tilt errors lead to erroneous measurement of snow albedo. These errors are corrected where tilts of sensors and slopes are unknown. Atmospheric parameters are taken from a nearby reference measurement or a radiation model. The developed model is fitted to the measured data to determine tilts and directions which vary daily due to changing atmospheric conditions and snow cover. The results show an obvious under- or overestimation of albedo depending on the slope direction.

Description: Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers Miles G. McPhee, Craig L. Stevens, Inga J. Smith, and Natalie J. Robinson Ocean Sci., 12, 507-515, doi:10.5194/os-12-507-2016, 2016 Measurements of turbulent heat fluxes in tidally modulated flow of supercool seawater under Antarctic land-fast sea ice show that turbulent heat exchange at the ocean–ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing. Also, the conditions cause platelet ice growth to form on the underside of the sea ice which increases the hydraulic roughness (drag) of fast ice compared to ice without platelets.

Description: Metamorphism during temperature gradient with undersaturated advective airflow in a snow sample Pirmin Philipp Ebner, Martin Schneebeli, and Aldo Steinfeld The Cryosphere, 10, 791-797, doi:10.5194/tc-10-791-2016, 2016 Changes of the porous ice structure were observed in a snow sample. Sublimation occurred due to the slight undersaturation of the incoming air into the warmer ice matrix. Diffusion of water vapor opposite to the direction of the temperature gradient counteracted the mass transport of advection. Therefore, the total net ice change was negligible, leading to a constant porosity profile. However, the strong recrystallization of water molecules in snow may impact its isotopic or chemical content.

Description: Quantifying ice loss in the eastern Himalayas since 1974 using declassified spy satellite imagery Joshua M. Maurer, Summer B. Rupper, and Joerg M. Schaefer The Cryosphere Discuss., doi:10.5194/tc-2016-48,2016 Manuscript under review for TC (discussion: open, 0 comments) Here we utilize declassified spy satellite imagery to quantify ice volume loss of glaciers in the eastern Himalayas over approximately the last three decades. Clean-ice and debris-covered glaciers show similar magnitudes of ice loss, while calving glaciers are contributing a disproportionately large amount to total ice loss. Results highlight important physical processes affecting the ice mass budget and associated water resources in the Himalayas.

Description: Continuous seiche in bays and harbors Joseph Park, Jamie MacMahan, William V. Sweet, and Kevin Kotun Ocean Sci., 12, 355-368, doi:10.5194/os-12-355-2016, 2016 Bays and harbors naturally resonate with standing waves, known as seiches. Seiches are usually considered temporary, however, we identify small-amplitude, continuously present seiches in six bays around the Pacific and suggest that tidally forced, continental shelf resonances are a primary driver of continuous seiches.

Description: Indian Ocean Dipole modulated wave climate of eastern Arabian Sea T. R. Anoop, V. Sanil Kumar, P. R. Shanas, J. Glejin, and M. M. Amrutha Ocean Sci., 12, 369-378, doi:10.5194/os-12-369-2016, 2016 Using measured, modeled and reanalysis wave data and reanalysis wind data, we show that the Indian Ocean Dipole (IOD) plays a role in the variability of wave climate of the eastern Arabian Sea (AS). The change in wind field over the AS due to IOD influences the generation or dissipation of wave field and hence causes the decrease in northwest short period waves during positive IOD and increase during negative IOD.

Description: Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes T. Krumpen, R. Gerdes, C. Haas, S. Hendricks, A. Herber, V. Selyuzhenok, L. Smedsrud, and G. Spreen The Cryosphere, 10, 523-534, doi:10.5194/tc-10-523-2016, 2016 We present an extensive data set of ground-based and airborne electromagnetic ice thickness measurements covering Fram Strait in summer between 2001 and 2012. An investigation of back trajectories of surveyed sea ice using satellite-based sea ice motion data allows us to examine the connection between thickness variability, ice age and source area. In addition, we determine across and along strait gradients in ice thickness and associated volume fluxes.

Description: Scaling-up Permafrost Thermal Measurements in Western Alaska using an Ecotype Approach William L. Cable, Vladimir E. Romanovsky, and M. Torre Jorgenson The Cryosphere Discuss., doi:10.5194/tc-2016-30,2016 Manuscript under review for TC (discussion: open, 0 comments) Permafrost temperatures in Alaska are increasing, yet in many areas we lack data needed to assess future changes and potential risks. In this paper we show that classifying the landscape into landcover types is an effective way to scale up permafrost temperature data collected from field monitoring sites. Based on these results, a map of mean annual ground temperature ranges at 1 m depth was produced. The map should be useful for land use decision making and identifying potential risk areas.

Description: The darkening of the Greenland ice sheet: trends, drivers, and projections (1981–2100) Marco Tedesco, Sarah Doherty, Xavier Fettweis, Patrick Alexander, Jeyavinoth Jeyaratnam, and Julienne Stroeve The Cryosphere, 10, 477-496, doi:10.5194/tc-10-477-2016, 2016 Summer surface albedo over Greenland decreased at a rate of 0.02 per decade between 1996 and 2012. The decrease is due to snow grain growth, the expansion of bare ice areas, and trends in light-absorbing impurities on snow and ice surfaces. Neither aerosol models nor in situ observations indicate increasing trends in impurities in the atmosphere over Greenland. Albedo projections through to the end of the century under different warming scenarios consistently point to continued darkening.

Description: IEOOS: the Spanish Institute of Oceanography Observing System Elena Tel, Rosa Balbin, Jose-Manuel Cabanas, Maria-Jesus Garcia, M. Carmen Garcia-Martinez, Cesar Gonzalez-Pola, Alicia Lavin, Jose-Luis Lopez-Jurado, Carmen Rodriguez, Manuel Ruiz-Villarreal, Ricardo F. Sánchez-Leal, Manuel Vargas-Yáñez, and Pedro Vélez-Belchí Ocean Sci., 12, 345-353, doi:10.5194/os-12-345-2016, 2016 The Spanish Institute of Oceanography supports different operational programmes in order to observe and measure ocean characteristics. Their combination allows responses to ocean research activities and marine ecosystem management, as well as official agency requirements and industrial and main society demands. All these networks are linked to international initiatives, framed largely in supranational Earth observation sponsored by the United Nations and the European Union.

Description: Brief Communication: Evidence of a developing Polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg Christopher J. Fogwill, Erik van Sebille, Eva A. Cougnon, Chris S. M. Turney, Steve R. Rintoul, Graeme F. Clark, E. M. Marzinelli, Eleanor B. Rainsley, and Lionel Carter The Cryosphere Discuss., doi:10.5194/tc-2016-19,2016 Manuscript under review for TC (discussion: open, 0 comments) Here we report new data from in situ oceanographic surveys and high-resolution ocean modelling experiments in the Commonwealth Bay region of East Antarctica, where in 2010 there was a major reconfiguration of the regional ice-scape due to the collision of the 97 km long iceberg B09B with the Mertz Glacier Tongue. Here we compare post-calving observations with high-resolution ocean modelling which suggest that this reconfiguration has led to the development of a new polynya off Commonwealth Bay.

Description: A fully automated methodology for differentiating rock from snow, clouds and sea in Antarctica from Landsat imagery: A new rock outcrop map and area estimation for the entire Antarctic continent Alex Burton-Johnson, Martin Black, Peter T. Fretwell, and Joseph Kaluza-Gilbert The Cryosphere Discuss., doi:10.5194/tc-2016-56,2016 Manuscript under review for TC (discussion: open, 0 comments) Differentiating exposed rock from snow and ice is a particular problem in Antarctica where extensive cloud cover and widespread shaded regions lead to classification errors. The existing rock outcrop dataset has significant georeferencing issues including overestimation and generalisation of rock exposure areas. The most commonly used method for automated rock and snow differentiation, the Normalised Difference Snow Index (NDSI), has difficulty differentiating rock and snow in Antarctica due to misclassification of shaded pixels and cannot differentiate illuminated rock from clouds. This study presents a new method for identifying rock exposures using Landsat 8 data. This is the first fully automated methodology for snow and rock differentiation that excludes areas of snow (both illuminated and shaded), clouds and liquid water whilst identifying both sunlit and shaded rock, achieving higher and more consistent accuracies than alternative data and methods such as the NDSI. The new methodology has been applied to the whole Antarctic continent (north of 82°40' S) using Landsat 8 data to produce a new rock outcrop dataset for Antarctica. The new data (merged with existing data south of 82°40' S) reveals that exposed rock forms 0.18 % of the total land area of Antarctica; half of previous estimates.

Description: Remote sensing of chlorophyll in the Baltic Sea at basin scale from 1997 to 2012 using merged multi-sensor data Jaime Pitarch, Gianluca Volpe, Simone Colella, Hajo Krasemann, and Rosalia Santoleri Ocean Sci., 12, 379-389, doi:10.5194/os-12-379-2016, 2016 Several operational satellite chlorophyll a (CHL) in the Baltic Sea were tested at a regional scale. Comparison to an extensive in situ CHL dataset showed low linearity. Bias-corrected CHL annual cycles were computed. The Gulf of Bothnia displays a single CHL peak during spring. In Skagerrak and Kattegat, there is a small bloom in spring and a minimum in summer. In the central Baltic, CHL follows a dynamic of a mild spring bloom followed by a much stronger bloom in summer.

Description: Use of an ultra-long-range terrestrial laser scanner to monitor the mass balance of very small glaciers in the Swiss Alps Mauro Fischer, Matthias Huss, Mario Kummert, and Martin Hoelzle The Cryosphere Discuss., doi:10.5194/tc-2016-46,2016 Manuscript under review for TC (discussion: open, 0 comments) Due to the relative lack of empirical field data, the response of very small glaciers ( 〈 0.5 km 2 ) to current atmospheric warming is not fully understood yet. Investigating their mass balance is a prerequisite to fill this knowledge gap. Application of the direct glaciological method is one option. Since most recently, terrestrial laser scanning (TLS) techniques operating in the near infrared range are successfully applied for the creation of repeated high-resolution digital elevation models and consecutive derivation of annual geodetic mass balances of very small glaciers. This method is promising, as laborious and potentially dangerous field measurements as well as the inter- and extrapolation of point measurements can be circumvented. However, it still owes to be validated. Here, we present TLS-derived annual surface elevation and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn, and Pizolgletscher) and two consecutive years (2013/14–2014/15). The scans were acquired with an ultra-long-range Riegl VZ-6000 especially designed for surveying snow- and ice-covered terrain. Zonally variable conversion factors for firn and bare ice surfaces were applied to convert geodetic volume to mass changes. We compare the geodetic results to direct glaciological mass balance measurements coinciding with the TLS surveys and carefully assess the uncertainties and errors included in both methods. Average glacier-wide mass balances were negative in both years, showing remarkably stronger mass losses in 2014/15 (−1.65 m w.e.) compared to 2013/14 (−0.59 m w.e.). Geodetic mass balances were slightly less negative but in close agreement with the direct glaciological ones ( R 2 = 0.91). Due to the very dense in-situ measurements, the uncertainties in the direct glaciological mass balances were small compared to the majority of measured glaciers worldwide (±0.09 m w.e. yr −1 on average), and similar to uncertainties in the TLS-derived geodetic mass balances (±0.13 m w.e. yr −1 ).

Description: Reanalysis of long-term series of glaciological and geodetic mass balance for 10 Norwegian glaciers Liss M. Andreassen, Hallgeir Elvehøy, Bjarne Kjøllmoen, and Rune V. Engeset The Cryosphere, 10, 535-552, doi:10.5194/tc-10-535-2016, 2016 This study provides homogenised and partly calibrated data series of glaciological and geodetic mass balance for the 10 Norwegian glaciers with long-term observations. In total, 21 periods of data were compared. Uncertainties were quantified for relevant sources of errors, both in the glaciological and geodetic series. The reanalysis processes altered seasonal, annual, and cumulative as well as ELA and AAR values for many of the years for the 10 glaciers presented.