ALBERT

Description: Impact of model developments on present and future simulations of permafrost in a global land-surface model The Cryosphere, 9, 1505-1521, 2015 Author(s): S. E. Chadburn, E. J. Burke, R. L. H. Essery, J. Boike, M. Langer, M. Heikenfeld, P. M. Cox, and P. Friedlingstein There is a large amount of organic carbon stored in permafrost in the northern high latitudes, which may become vulnerable to microbial decomposition under future climate warming. In order to estimate this potential carbon–climate feedback it is necessary to correctly simulate the physical dynamics of permafrost within global Earth system models (ESMs) and to determine the rate at which it will thaw. Additional new processes within JULES, the land-surface scheme of the UK ESM (UKESM), include a representation of organic soils, moss and bedrock and a modification to the snow scheme; the sensitivity of permafrost to these new developments is investigated in this study. The impact of a higher vertical soil resolution and deeper soil column is also considered. Evaluation against a large group of sites shows the annual cycle of soil temperatures is approximately 25 % too large in the standard JULES version, but this error is corrected by the model improvements, in particular by deeper soil, organic soils, moss and the modified snow scheme. A comparison with active layer monitoring sites shows that the active layer is on average just over 1 m too deep in the standard model version, and this bias is reduced by 70 cm in the improved version. Increasing the soil vertical resolution allows the full range of active layer depths to be simulated; by contrast, with a poorly resolved soil at least 50 % of the permafrost area has a maximum thaw depth at the centre of the bottom soil layer. Thus all the model modifications are seen to improve the permafrost simulations. Historical permafrost area corresponds fairly well to observations in all simulations, covering an area between 14 and 19 million km 2 . Simulations under two future climate scenarios show a reduced sensitivity of permafrost degradation to temperature, with the near-surface permafrost loss per degree of warming reduced from 1.5 million km 2 °C −1 in the standard version of JULES to between 1.1 and 1.2 million km 2 °C −1 in the new model version. However, the near-surface permafrost area is still projected to approximately half by the end of the 21st century under the RCP8.5 scenario.

Description: Statistical detection and modeling of the over-dispersion of winter storm occurrence Natural Hazards and Earth System Science, 15, 1757-1761, 2015 Author(s): M. Raschke In this communication, I improve the detection and modeling of the over-dispersion of winter storm occurrence. For this purpose, the generalized Poisson distribution and the Bayesian information criterion are introduced; the latter is used for statistical model selection. Moreover, I replace the frequently used dispersion statistics by an over-dispersion parameter which does not depend on the considered return period of storm events. These models and methods are applied in order to properly detect the over-dispersion in winter storm data for Germany, carrying out a joint estimation of the distribution models for different samples.

Description: Impacts on wave-driven harbour agitation due to climate change in Catalan ports Natural Hazards and Earth System Science, 15, 1695-1709, 2015 Author(s): J. P. Sierra, M. Casas-Prat, M. Virgili, C. Mösso, and A. Sánchez-Arcilla The objective of the present work is to analyse how changes in wave patterns due to the effect of climate change can affect harbour agitation (oscillations within the port due to wind waves). The study focuses on 13 harbours located on the Catalan coast (NW Mediterranean) using a methodology with general applicability. To obtain the patterns of agitation, a Boussinesq-type model is used, which is forced at the boundaries by present/future offshore wave conditions extracted from recently developed high-resolution wave projections in the NW Mediterranean. These wave projections were obtained with the SWAN model forced by present/future surface wind fields projected, respectively, by five different combinations of global and regional circulation models (GCMs and RCMs) for the A1B scenario. The results show a general slight reduction in the annual average agitation for most of the ports, except for the northernmost and southernmost areas of the region, where a slight increase is obtained. A seasonal analysis reveals that the tendency to decrease is accentuated in winter. However, the inter-model variability is large for both the winter and the annual analysis. Conversely, a general increase with a larger agreement among models is found during summer, which is the period with greater activity in most of the studied ports (marinas). A qualitative assessment of the factors of variability seems to indicate that the choice of GCM tends to affect the spatial pattern, whereas the choice of RCM induces a more homogeneous bias over the regional domain.

Description: Assimilation of Antarctic velocity observations provides evidence for uncharted pinning points The Cryosphere, 9, 1427-1443, 2015 Author(s): J. J. Fürst, G. Durand, F. Gillet-Chaulet, N. Merino, L. Tavard, J. Mouginot, N. Gourmelen, and O. Gagliardini In ice flow modelling, the use of control methods to assimilate the dynamic and geometric state of an ice body has become common practice. These methods have primarily focussed on inverting for one of the two least known properties in glaciology, namely the basal friction coefficient or the ice viscosity parameter. Here, we present an approach to infer both properties simultaneously for the whole of the Antarctic ice sheet. After the assimilation, the root-mean-square deviation between modelled and observed surface velocities attains 8.7 m a −1 for the entire domain, with a slightly higher value of 14.0 m a −1 for the ice shelves. An exception in terms of the velocity mismatch is the Thwaites Glacier Ice Shelf, where the RMS value is almost 70 m a −1 . The reason is that the underlying Bedmap2 geometry ignores the presence of an ice rise, which exerts major control on the dynamics of the eastern part of the ice shelf. On these grounds, we suggest an approach to account for pinning points not included in Bedmap2 by locally allowing an optimisation of basal friction during the inversion. In this way, the velocity mismatch on the ice shelf of Thwaites Glacier is more than halved. A characteristic velocity mismatch pattern emerges for unaccounted pinning points close to the marine shelf front. This pattern is exploited to manually identify seven uncharted features around Antarctica that exert significant resistance to the shelf flow. Potential pinning points are detected on Fimbul, West, Shackleton, Nickerson and Venable ice shelves. As pinning points can provide substantial resistance to shelf flow, with considerable consequences if they became ungrounded in the future, the model community is in need of detailed bathymetry there. Our data assimilation points to some of these dynamically important features not present in Bedmap2 and implicitly quantifies their relevance.

Description: Towards predictive data-driven simulations of wildfire spread – Part II: Ensemble Kalman Filter for the state estimation of a front-tracking simulator of wildfire spread Natural Hazards and Earth System Science, 15, 1721-1739, 2015 Author(s): M. C. Rochoux, C. Emery, S. Ricci, B. Cuenot, and A. Trouvé This paper is the second part in a series of two articles, which aims at presenting a data-driven modeling strategy for forecasting wildfire spread scenarios based on the assimilation of the observed fire front location and on the sequential correction of model parameters or model state. This model relies on an estimation of the local rate of fire spread (ROS) as a function of environmental conditions based on Rothermel's semi-empirical formulation, in order to propagate the fire front with an Eulerian front-tracking simulator. In Part I, a data assimilation (DA) system based on an ensemble Kalman filter (EnKF) was implemented to provide a spatially uniform correction of biomass fuel and wind parameters and thereby, produce an improved forecast of the wildfire behavior (addressing uncertainties in the input parameters of the ROS model only). In Part II, the objective of the EnKF algorithm is to sequentially update the two-dimensional coordinates of the markers along the discretized fire front, in order to provide a spatially distributed correction of the fire front location and thereby, a more reliable initial condition for further model time-integration (addressing all sources of uncertainties in the ROS model). The resulting prototype data-driven wildfire spread simulator is first evaluated in a series of verification tests using synthetically generated observations; tests include representative cases with spatially varying biomass properties and temporally varying wind conditions. In order to properly account for uncertainties during the EnKF update step and to accurately represent error correlations along the fireline, it is shown that members of the EnKF ensemble must be generated through variations in estimates of the fire's initial location as well as through variations in the parameters of the ROS model. The performance of the prototype simulator based on state estimation (SE) or parameter estimation (PE) is then evaluated by comparison with data taken from a reduced-scale controlled grassland fire experiment. Results indicate that data-driven simulations are capable of correcting inaccurate predictions of the fire front location and of subsequently providing an optimized forecast of the wildfire behavior at future lead times. The complementary benefits of both PE and SE approaches, in terms of analysis and forecast performance, are also emphasized. In particular, it is found that the size of the assimilation window must be specified adequately with the persistence of the model initial condition and/or with the temporal and spatial variability of the environmental conditions in order to track sudden changes in wildfire behavior. The present prototype data-driven forecast system is still at an early stage of development. In this regard, this preliminary investigation provides valuable information on how to combine observations with a fire spread model in an efficient way, as well as guidelines to design the future system evolution in order to meet the operational requirements of wildfire spread monitoring.

Description: Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate The Cryosphere, 9, 1579-1600, 2015 Author(s): S. L. Cornford, D. F. Martin, A. J. Payne, E. G. Ng, A. M. Le Brocq, R. M. Gladstone, T. L. Edwards, S. R. Shannon, C. Agosta, M. R. van den Broeke, H. H. Hellmer, G. Krinner, S. R. M. Ligtenberg, R. Timmermann, and D. G. Vaughan We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.

Description: A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front induced by rainfall infiltration Natural Hazards and Earth System Science, 15, 1835-1849, 2015 Author(s): B.-G. Chae, J.-H. Lee, H.-J. Park, and J. Choi Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steady-state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady-state approach.

Description: Regional trends and controlling factors of fatal landslides in Latin America and the Caribbean Natural Hazards and Earth System Science, 15, 1821-1833, 2015 Author(s): S. A. Sepúlveda and D. N. Petley A new data set of landslides that caused loss of life in Latin America and the Caribbean in the 10-year period from 2004 and 2013 inclusive has been compiled, providing new insight into the impact of landslides in this key part of the world. This data set indicates that in the 10-year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landslides is highly heterogeneous, with areas of high incidence in parts of the Caribbean (most notably Haiti), Central America, Colombia, and southeast Brazil. There is significant interannual variation in the number of landslides, with the El Niño/La Niña cycle emerging as a key control. Our analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. On a national basis we have compared the occurrence of fatality-inducing landslide occurrence with the production of locally authored research articles, demonstrating that there is a landslide research deficit in Latin America and the Caribbean. Understanding better the mechanisms, distribution causes and triggers of landslides in Latin America and the Caribbean must be an essential first step towards managing the hazard.

Description: Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core The Cryosphere, 9, 1633-1648, 2015 Author(s): J.-L. Tison, M. de Angelis, G. Littot, E. Wolff, H. Fischer, M. Hansson, M. Bigler, R. Udisti, A. Wegner, J. Jouzel, B. Stenni, S. Johnsen, V. Masson-Delmotte, A. Landais, V. Lipenkov, L. Loulergue, J.-M. Barnola, J.-R. Petit, B. Delmonte, G. Dreyfus, D. Dahl-Jensen, G. Durand, B. Bereiter, A. Schilt, R. Spahni, K. Pol, R. Lorrain, R. Souchez, and D. Samyn An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ 18 O ice , δ 18 O atm , total air content, CO 2 , CH 4 , N 2 O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris from the ice sheet's substrate. We further discuss how the proposed mechanism is compatible with the other ice properties described. We conclude that the paleoclimatic signal is only marginally affected in terms of global ice properties at the bottom of EPICA Dome C, but that the timescale was considerably distorted by mechanical stretching of MIS20 due to the increasing influence of the subglacial topography, a process that might have started well above the bottom ice. A clear paleoclimatic signal can therefore not be inferred from the deeper part of the EPICA Dome C ice core. Our work suggests that the existence of a flat monotonic ice–bedrock interface, extending for several times the ice thickness, would be a crucial factor in choosing a future "oldest ice" drilling location in Antarctica.

Description: Impact of debris cover on glacier ablation and atmosphere–glacier feedbacks in the Karakoram The Cryosphere, 9, 1617-1632, 2015 Author(s): E. Collier, F. Maussion, L. I. Nicholson, T. Mölg, W. W. Immerzeel, and A. B. G. Bush The Karakoram range of the Hindu-Kush Himalaya is characterized by both extensive glaciation and a widespread prevalence of surficial debris cover on the glaciers. Surface debris exerts a strong control on glacier surface-energy and mass fluxes and, by modifying surface boundary conditions, has the potential to alter atmosphere–glacier feedbacks. To date, the influence of debris on Karakoram glaciers has only been directly assessed by a small number of glaciological measurements over short periods. Here, we include supraglacial debris in a high-resolution, interactively coupled atmosphere–glacier modeling system. To investigate glaciological and meteorological changes that arise due to the presence of debris, we perform two simulations using the coupled model from 1 May to 1 October 2004: one that treats all glacier surfaces as debris-free and one that introduces a simplified specification for the debris thickness. The basin-averaged impact of debris is a reduction in ablation of ~ 14 %, although the difference exceeds 5 m w.e. on the lowest-altitude glacier tongues. The relatively modest reduction in basin-mean mass loss results in part from non-negligible sub-debris melt rates under thicker covers and from compensating increases in melt under thinner debris, and may help to explain the lack of distinct differences in recent elevation changes between clean and debris-covered ice. The presence of debris also strongly alters the surface boundary condition and thus heat exchanges with the atmosphere; near-surface meteorological fields at lower elevations and their vertical gradients; and the atmospheric boundary layer development. These findings are relevant for glacio-hydrological studies on debris-covered glaciers and contribute towards an improved understanding of glacier behavior in the Karakoram.

Description: Drought assessment in the Dongliao River basin: traditional approaches vs. generalized drought assessment index based on water resources systems Natural Hazards and Earth System Science, 15, 1889-1906, 2015 Author(s): B. S. Weng, D. H. Yan, H. Wang, J. H. Liu, Z. Y. Yang, T. L. Qin, and J. Yin Drought is firstly a resource issue, and with its development it evolves into a disaster issue. Drought events usually occur in a determinate but a random manner. Drought has become one of the major factors to affect sustainable socioeconomic development. In this paper, we propose the generalized drought assessment index (GDAI) based on water resources systems for assessing drought events. The GDAI considers water supply and water demand using a distributed hydrological model. We demonstrate the use of the proposed index in the Dongliao River basin in northeastern China. The results simulated by the GDAI are compared to observed drought disaster records in the Dongliao River basin. In addition, the temporal distribution of drought events and the spatial distribution of drought frequency from the GDAI are compared with the traditional approaches in general (i.e., standard precipitation index, Palmer drought severity index and rate of water deficit index). Then, generalized drought times, generalized drought duration, and generalized drought severity were calculated by theory of runs. Application of said runs at various drought levels (i.e., mild drought, moderate drought, severe drought, and extreme drought) during the period 1960–2010 shows that the centers of gravity of them all distribute in the middle reaches of Dongliao River basin, and change with time. The proposed methodology may help water managers in water-stressed regions to quantify the impact of drought, and consequently, to make decisions for coping with drought.

Description: Hydroelastic analysis of ice shelves under long wave excitation Natural Hazards and Earth System Science, 15, 1851-1857, 2015 Author(s): T. K. Papathanasiou, A. E. Karperaki, E. E. Theotokoglou, and K. A. Belibassakis The transient hydroelastic response of an ice shelf under long wave excitation is analysed by means of the finite element method. The simple model, presented in this work, is used for the simulation of the generated kinematic and stress fields in an ice shelf, when the latter interacts with a tsunami wave. The ice shelf, being of large length compared to its thickness, is modelled as an elastic Euler-Bernoulli beam, constrained at the grounding line. The hydrodynamic field is represented by the linearised shallow water equations. The numerical solution is based on the development of a special hydroelastic finite element for the system of governing of equations. Motivated by the 2011 Sulzberger Ice Shelf (SIS) calving event and its correlation with the Honshu Tsunami, the SIS stable configuration is studied. The extreme values of the bending moment distribution in both space and time are examined. Finally, the location of these extrema is investigated for different values of ice shelf thickness and tsunami wave length.

Description: Pre-earthquake magnetic pulses Natural Hazards and Earth System Science, 15, 1873-1880, 2015 Author(s): J. Scoville, J. Heraud, and F. Freund A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are suspected to be generated deep in the Earth's crust, in and around the hypocentral volume, days or even weeks before earthquakes. Their extremely long wavelength allows them to pass through kilometers of rock. Interestingly, when the sources of these pulses are triangulated, the locations coincide with the epicenters of future earthquakes. We couple a drift-diffusion semiconductor model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.

Description: Mediterranean cyclone characteristics related to precipitation occurrence in Crete, Greece Natural Hazards and Earth System Science, 15, 1807-1819, 2015 Author(s): V. Iordanidou, A. G. Koutroulis, and I. K. Tsanis The characteristics of the cyclone tracks that caused precipitation events of variable intensity for the period 1979–2011 over the island of Crete are presented. The data set used for cyclone identification is the 0.5° × 0.5°, 30 years European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim mean sea-level pressure. Cyclone characteristics are calculated with the aid of the Melbourne University algorithm (MS scheme). Daily precipitation data from a dense gauging network over the island of Crete are also used for the classification of the precipitation events in terms of rain accumulation (intensity). Daily precipitation is classified in three categories and the associated cyclones are chosen according to their distance from Crete island. The seasonal and annual cycle of the physical characteristics of the cyclone tracks are investigated with respect to the cyclones' relative position to the island of Crete. It was found that cyclones affecting Crete most frequently approach from the western side of the island and the actual cyclone centers associated with precipitation events are usually located northwest and southeast of the Crete domain. Cyclone-induced rainfall increases in function to cyclones' depth, radius and propagation velocity increase as well as cyclones' pressure decrease. Spring cyclones that affect Crete with rainfall present lower pressures and higher cyclone propagation velocity in contrast to the ones associated with winter and autumn precipitation events. The examination of the relation between cyclone characteristics and precipitation occurrence provides valuable information related to forecasting potential and management of the water resources and the rainfall extremes.

Description: Probabilistic hurricane-induced storm surge hazard assessment in Guadeloupe, Lesser Antilles Natural Hazards and Earth System Science, 15, 1711-1720, 2015 Author(s): Y. Krien, B. Dudon, J. Roger, and N. Zahibo Current storm surge hazard maps in the French West Indies are essentially based on simple statistical methods using limited historical data and early low-resolution models which do not take the effect of waves into account. In this paper, we infer new 100-year and 1000-year surge levels in Guadeloupe from the numerical modelling of storm surges induced by a large set of synthetic events that are in statistical agreement with features of historical hurricanes in the North Atlantic Basin between 1980 and 2011. Computations are performed using the wave-current coupled model ADCIRC–SWAN with high grid resolutions (up to 40–60 m) in the coastal and wave dissipation areas. This model is validated against observations during past events such as hurricane HUGO (1989). Results are generally found to be in reasonable agreement with past studies in areas where surge is essentially wind-driven, but found to differ significantly in coastal regions where the transfer of momentum from waves to the water column constitutes a non-negligible part of the total surge. The methodology, which can be applied to other islands in the Lesser Antilles, allows storm surge level maps to be obtained that can be of major interest for coastal planners and decision makers in terms of risk management.

Description: Mapping snow depth from manned aircraft on landscape scales at centimeter resolution using structure-from-motion photogrammetry The Cryosphere, 9, 1445-1463, 2015 Author(s): M. Nolan, C. Larsen, and M. Sturm Airborne photogrammetry is undergoing a renaissance: lower-cost equipment, more powerful software, and simplified methods have significantly lowered the barriers to entry and now allow repeat mapping of cryospheric dynamics at spatial resolutions and temporal frequencies that were previously too expensive to consider. Here we apply these advancements to the measurement of snow depth from manned aircraft. Our main airborne hardware consists of a consumer-grade digital camera directly coupled to a dual-frequency GPS; no inertial motion unit (IMU) or on-board computer is required, such that system hardware and software costs less than USD 30 000, exclusive of aircraft. The photogrammetric processing is done using a commercially available implementation of the structure from motion (SfM) algorithm. The system is simple enough that it can be operated by the pilot without additional assistance and the technique creates directly georeferenced maps without ground control, further reducing overall costs. To map snow depth, we made digital elevation models (DEMs) during snow-free and snow-covered conditions, then subtracted these to create difference DEMs (dDEMs). We assessed the accuracy (real-world geolocation) and precision (repeatability) of our DEMs through comparisons to ground control points and to time series of our own DEMs. We validated these assessments through comparisons to DEMs made by airborne lidar and by a similar photogrammetric system. We empirically determined that our DEMs have a geolocation accuracy of ±30 cm and a repeatability of ±8 cm (both 95 % confidence). We then validated our dDEMs against more than 6000 hand-probed snow depth measurements at 3 separate test areas in Alaska covering a wide-variety of terrain and snow types. These areas ranged from 5 to 40 km 2 and had ground sample distances of 6 to 20 cm. We found that depths produced from the dDEMs matched probe depths with a 10 cm standard deviation, and were statistically identical at 95 % confidence. Due to the precision of this technique, other real changes on the ground such as frost heave, vegetative compaction by snow, and even footprints become sources of error in the measurement of thin snow packs ( 〈 20 cm). The ability to directly measure such small changes over entire landscapes eliminates the need to extrapolate limited field measurements. The fact that this mapping can be done at substantially lower costs than current methods may transform the way we approach studying change in the cryosphere.

Description: Recent changes in north-west Greenland climate documented by NEEM shallow ice core data and simulations, and implications for past-temperature reconstructions The Cryosphere, 9, 1481-1504, 2015 Author(s): V. Masson-Delmotte, H. C. Steen-Larsen, P. Ortega, D. Swingedouw, T. Popp, B. M. Vinther, H. Oerter, A. E. Sveinbjornsdottir, H. Gudlaugsdottir, J. E. Box, S. Falourd, X. Fettweis, H. Gallée, E. Garnier, V. Gkinis, J. Jouzel, A. Landais, B. Minster, N. Paradis, A. Orsi, C. Risi, M. Werner, and J. W. C. White Combined records of snow accumulation rate, δ 18 O and deuterium excess were produced from several shallow ice cores and snow pits at NEEM (North Greenland Eemian Ice Drilling), covering the period from 1724 to 2007. They are used to investigate recent climate variability and characterise the isotope–temperature relationship. We find that NEEM records are only weakly affected by inter-annual changes in the North Atlantic Oscillation. Decadal δ 18 O and accumulation variability is related to North Atlantic sea surface temperature and is enhanced at the beginning of the 19th century. No long-term trend is observed in the accumulation record. By contrast, NEEM δ 18 O shows multidecadal increasing trends in the late 19th century and since the 1980s. The strongest annual positive δ 18 O values are recorded at NEEM in 1928 and 2010, while maximum accumulation occurs in 1933. The last decade is the most enriched in δ 18 O (warmest), while the 11-year periods with the strongest depletion (coldest) are depicted at NEEM in 1815–1825 and 1836–1846, which are also the driest 11-year periods. The NEEM accumulation and δ 18 O records are strongly correlated with outputs from atmospheric models, nudged to atmospheric reanalyses. Best performance is observed for ERA reanalyses. Gridded temperature reconstructions, instrumental data and model outputs at NEEM are used to estimate the multidecadal accumulation–temperature and δ 18 O–temperature relationships for the strong warming period in 1979–2007. The accumulation sensitivity to temperature is estimated at 11 ± 2 % °C −1 and the δ 18 O–temperature slope at 1.1 ± 0.2 ‰ °C −1 , about twice as large as previously used to estimate last interglacial temperature change from the bottom part of the NEEM deep ice core.

Description: Evolution of ice-shelf channels in Antarctic ice shelves The Cryosphere, 9, 1169-1181, 2015 Author(s): R. Drews Ice shelves buttress the continental ice flux and mediate ice–ocean interactions. They are often traversed by channels in which basal melting is enhanced, impacting ice-shelf stability. Here, channel evolution is investigated using a transient, three-dimensional full Stokes model and geophysical data collected on the Roi Baudouin Ice Shelf (RBIS), Antarctica. The modeling confirms basal melting as a feasible mechanism for channel creation, although channels may also advect without melting for many tens of kilometers. Channels can be out of hydrostatic equilibrium depending on their width and the upstream melt history. Inverting surface elevation for ice thickness using hydrostatic equilibrium in those areas is erroneous, and corresponding observational evidence is presented at RBIS by comparing the hydrostatically inverted ice thickness with radar measurements. The model shows that channelized melting imprints the flow field characteristically, which can result in enhanced horizontal shearing across channels. This is exemplified for a channel at RBIS using observed surface velocities and opens up the possibility to classify channelized melting from space, an important step towards incorporating these effects in ice–ocean models.

Description: Hydrochemical characteristics of hot spring waters in the Kangding district related to the Lushan M S = 7.0 earthquake in Sichuan, China Natural Hazards and Earth System Science, 15, 1149-1156, 2015 Author(s): Z. Chen, X. Zhou, J. Du, C. Xie, L. Liu, Y. Li, L. Yi, H. Liu, and Y. Cui Hydrogeochemistry of 10 hot springs in the Kangding district was investigated by analyzing cation and anion concentrations in the spring water. The water samples were collected in the 5 days after the Lushan M S = 7.0 earthquake, which occurred on 20 April 2013. The spring waters are classified into seven chemical types based on their hydrochemical compositions. Compared with hydrochemical data before the Lushan earthquake, concentrations of Ca 2+ , HCO 3 - and total dissolved solid (TDS) in water samples from the Guanding, Erdaoqiao, Gonghe, Erhaoying, Tianwanhe and Caoke springs significantly increased, which may be the result of a greater increase in groundwater from carbonate rocks, and water–carbonate rock interactions, enhanced by the increment of CO 2 . Concentrations of Na + , Cl - and SO 4 2- in water samples from the Guanding, Zheduotang, Xinxing and Gonghe springs decreased, indicating a dilution of shallow waters. Concentrations of Na + and SO 4 2- in water samples from the Erhaoying spring water increased, which may be attributed to water–granite interactions enhanced by H 2 S. The results indicated that hydrochemical components of spring water could be used as an effective indicator for earthquakes.

Description: Preface: Current advances in analysis, modelling and mitigation of the costs of natural hazards Natural Hazards and Earth System Science, 15, 1157-1162, 2015 Author(s): H. Kreibich, L. M. Bouwer, and R. Schwarze

Description: How historical information can improve estimation and prediction of extreme coastal water levels: application to the Xynthia event at La Rochelle (France) Natural Hazards and Earth System Science, 15, 1135-1147, 2015 Author(s): T. Bulteau, D. Idier, J. Lambert, and M. Garcin The knowledge of extreme coastal water levels is useful for coastal flooding studies or the design of coastal defences. While deriving such extremes with standard analyses using tide-gauge measurements, one often needs to deal with limited effective duration of observation which can result in large statistical uncertainties. This is even truer when one faces the issue of outliers, those particularly extreme values distant from the others which increase the uncertainty on the results. In this study, we investigate how historical information, even partial, of past events reported in archives can reduce statistical uncertainties and relativise such outlying observations. A Bayesian Markov chain Monte Carlo method is developed to tackle this issue. We apply this method to the site of La Rochelle (France), where the storm Xynthia in 2010 generated a water level considered so far as an outlier. Based on 30 years of tide-gauge measurements and 8 historical events, the analysis shows that (1) integrating historical information in the analysis greatly reduces statistical uncertainties on return levels (2) Xynthia's water level no longer appears as an outlier, (3) we could have reasonably predicted the annual exceedance probability of that level beforehand (predictive probability for 2010 based on data until the end of 2009 of the same order of magnitude as the standard estimative probability using data until the end of 2010). Such results illustrate the usefulness of historical information in extreme value analyses of coastal water levels, as well as the relevance of the proposed method to integrate heterogeneous data in such analyses.

Description: User requirements for the snow and land ice services – CryoLand The Cryosphere, 9, 1191-1202, 2015 Author(s): E. Malnes, A. Buanes, T. Nagler, G. Bippus, D. Gustafsson, C. Schiller, S. Metsämäki, J. Pulliainen, K. Luojus, H. E. Larsen, R. Solberg, A. Diamandi, and A. Wiesmann CryoLand (2011–2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired.

Description: READY: a web-based geographical information system for enhanced flood resilience through raising awareness in citizens Natural Hazards and Earth System Science, 15, 1645-1658, 2015 Author(s): R. Albano, A. Sole, and J. Adamowski As evidenced by the EU Floods Directive (2007/60/EC), flood management strategies in Europe have undergone a shift in focus in recent years. The goal of flood prevention using structural measures has been replaced by an emphasis on the management of flood risks using non-structural measures. One implication of this is that public authorities alone not only take responsibility for flood management. A broader range of stakeholders, who may personally experience the negative effects of flooding, also take on responsibility for protecting themselves. Therefore, it is vital that information concerning flood risks is conveyed to those who may be affected in order to facilitate the self-protection of citizens. Experience shows that problems persist even where efforts have been made to communicate flood risks. There is a need for the development of new tools that are able to rapidly disseminate flood-risk information to the general public. To be useful these tools must be able to present information relevant to the location of the user. Moreover, the content and design of the tool need to be adjusted to laypeople's needs. Dissemination and communication influence both people's access to and understanding of natural risk information. Such a tool could be a useful aid to effective management of flood risks. To address this gap, a web-based geographical information system (WebGIS) has been developed through the collaborative efforts of a group of scientists, hazard and risk analysts and managers, GIS analysts, system developers and communication designers. This tool, called "READY: Risk, Extreme Events, Adaptation, Defend Yourself", aims to enhance the general public knowledge of flood risk, making citizens more capable of responding appropriately during a flood event. The READY WebGIS has allowed for the visualization and easy querying of a complex hazard and risk database thanks to a high degree of interactivity and easily read maps. In this way, READY has enabled fast exploration of alternative flood scenarios or past calamitous events. Combined also with a system of graphic symbols designed ad hoc for communication of self-protection behaviours, it is believed READY could lead to an increase in citizen participation, informed discussion and consensus building. The platform has been developed for a site-specific application: the Basilicata region, Italy, has been selected as pilot application area. The goal of the prototype is to raise citizen awareness of flood risks and to build social capacity and enhanced resilience to flood events.

Description: Meteorological, elevation, and slope effects on surface hoar formation The Cryosphere, 9, 1523-1533, 2015 Author(s): S. Horton, M. Schirmer, and B. Jamieson Failure in layers of buried surface hoar crystals (frost) can cause hazardous snow slab avalanches. Surface hoar crystals form on the snow surface and are sensitive to micro-meteorological conditions. In this study, the role of meteorological and terrain factors was investigated for three layers of surface hoar in the Columbia Mountains of Canada. The distribution of crystals over different elevations and aspects was observed on 20 days of field observations during a period of high pressure. The same layers were modelled over simplified terrain on a 2.5 km horizontal grid by forcing the snow cover model SNOWPACK with forecast weather data from a numerical weather prediction model. Modelled surface hoar growth was associated with warm air temperatures, high humidity, cold surface temperatures, and low wind speeds. Surface hoar was most developed in regions and elevation bands where these conditions existed, although strong winds at high elevations caused some model discrepancies. SNOWPACK simulations on virtual slopes systematically predicted smaller surface hoar on south-facing slopes. In the field, a complex combination of surface hoar and sun crusts were observed, suggesting the simplified model did not adequately resolve the surface energy balance on slopes. Overall, a coupled weather–snow cover model could benefit avalanche forecasters by predicting surface hoar layers on a regional scale over different elevation bands.

Description: Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014 The Cryosphere, 9, 1535-1550, 2015 Author(s): C. Papasodoro, E. Berthier, A. Royer, C. Zdanowicz, and A. Langlois Grinnell and Terra Nivea Ice Caps are located on the southern Baffin Island, Nunavut, in the Canadian Arctic Archipelago. These relatively small ice caps have received little attention compared to the much larger ice masses further north. Their evolution can, however, give valuable information about the impact of the recent Arctic warming at lower latitudes (i.e. ~ 62.5° N). In this paper, we measure or estimate historical and recent changes of area, elevation and mass of both ice caps using in situ, airborne and spaceborne data sets, including imagery from the Pléiades satellites. The area of Terra Nivea Ice Cap has decreased by 34 % since the late 1950s, while that of Grinnell Ice Cap has decreased by 20 % since 1952. For both ice caps, the areal reduction accelerated at the beginning of the 21st century. The estimated glacier-wide mass balance was −0.37 ± 0.21 m a −1 water equivalent (w.e.) over Grinnell Ice Cap for the 1952–2014 period, and −0.47 ± 0.16 m a −1 w.e. over Terra Nivea Ice Cap for the 1958/59–2014 period. Terra Nivea Ice Cap has experienced an accelerated rate of mass loss of −1.77 ± 0.36 m a −1 w.e. between 2007 and 2014. This rate is 5.9 times as negative when compared to the 1958/59–2007 period (−0.30 ± 0.19 m a −1 w.e.) and 2 times as negative when compared to the mass balance of other glaciers in the southern parts of Baffin Island over the 2003–2009 period. A similar acceleration in mass loss is suspected for the Grinnell Ice Cap, given the calculated elevation changes and the proximity to Terra Nivea Ice Cap. The recent increase in mass loss rates for these two ice caps is linked to a strong near-surface regional warming and a lengthening of the melt season into the autumn that may be indirectly strengthened by a later freezing of sea ice in the Hudson Strait sector. On a methodological level, our study illustrates the strong potential of Pléiades satellite data to unlock the under-exploited archive of old aerial photographs.

Description: Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific Natural Hazards and Earth System Science, 15, 1763-1784, 2015 Author(s): G. Lamarche, S. Popinet, B. Pelletier, J. Mountjoy, J. Goff, S. Delaux, and J. Bind We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the island of Alofi form the Horn Archipelago located ca. 240 km east of Wallis. They are surrounded by a narrow fringing reef. Futuna and Alofi emerge from the North Fiji Transform Fault that marks the seismically active Pacific-Australia plate boundary. We generated 15 tsunami scenarios. For each, we calculated maximum wave elevation (MWE), inundation distance and expected time of arrival (ETA). The tsunami sources were local, regional and distant earthquake faults located along the Pacific Rim. In Wallis, the outer reef may experience 6.8 m-high MWE. Uvéa is protected by the barrier reef and the lagoon, but inundation depths of 2–3 m occur in several coastal areas. In Futuna, flow depths exceeding 2 m are modelled in several populated areas, and have been confirmed by a post-September 2009 South Pacific tsunami survey. The channel between the islands of Futuna and Alofi amplified the 2009 tsunami, which resulted in inundation distance of almost 100 m and MWE of 4.4 m. This first ever tsunami hazard modelling study of Wallis and Futuna compares well with palaeotsunamis recognised on both islands and observation of the impact of the 2009 South Pacific tsunami. The study provides evidence for the mitigating effect of barrier and fringing reefs from tsunamis.

Description: Predicting storm-triggered debris flow events: application to the 2009 Ionian Peloritan disaster (Sicily, Italy) Natural Hazards and Earth System Science, 15, 1785-1806, 2015 Author(s): M. Cama, L. Lombardo, C. Conoscenti, V. Agnesi, and E. Rotigliano The main assumption on which landslide susceptibility assessment by means of stochastic modelling lies is that the past is the key to the future. As a consequence, a stochastic model able to classify past known landslide events should be able to predict a future unknown scenario as well. However, storm-triggered multiple debris flow events in the Mediterranean region could pose some limits on the operative validity of such an expectation, as they are typically resultant of a randomness in time recurrence and magnitude and a great spatial variability, even at the scale of small catchments. This is the case for the 2007 and 2009 storm events, which recently hit north-eastern Sicily with different intensities, resulting in largely different disaster scenarios. The study area is the small catchment of the Itala torrent (10 km 2 ), which drains from the southern Peloritani Mountains eastward to the Ionian Sea, in the territory of the Messina province (Sicily, Italy). Landslides have been mapped by integrating remote and field surveys, producing two event inventories which include 73 debris flows, activated in 2007, and 616 debris flows, triggered by the 2009 storm. Logistic regression was applied in order to obtain susceptibility models which utilize a set of predictors derived from a 2 m cell digital elevation model and a 1 : 50 000 scale geologic map. The research topic was explored by performing two types of validation procedures: self-validation, based on the random partition of each event inventory, and chrono-validation, based on the time partition of the landslide inventory. It was therefore possible to analyse and compare the performances both of the 2007 calibrated model in predicting the 2009 debris flows (forward chrono-validation), and vice versa of the 2009 calibrated model in predicting the 2007 debris flows (backward chrono-validation). Both of the two predictions resulted in largely acceptable performances in terms of fitting, skill and reliability. However, a loss of performance and differences in the selected predictors arose between the self-validated and the chrono-validated models. These are interpreted as effects of the non-linearity in the domain of the trigger intensity of the relationships between predictors and slope response, as well as in terms of the different spatial paths of the two triggering storms at the catchment scale.

Description: Melt pond fraction and spectral sea ice albedo retrieval from MERIS data – Part 2: Case studies and trends of sea ice albedo and melt ponds in the Arctic for years 2002–2011 The Cryosphere, 9, 1567-1578, 2015 Author(s): L. Istomina, G. Heygster, M. Huntemann, H. Marks, C. Melsheimer, E. Zege, A. Malinka, A. Prikhach, and I. Katsev The spatial and temporal dynamics of melt ponds and sea ice albedo contain information on the current state and the trend of the climate of the Arctic region. This publication presents a study on melt pond fraction (MPF) and sea ice albedo spatial and temporal dynamics obtained with the Melt Pond Detection (MPD) retrieval scheme for the Medium Resolution Imaging Spectrometer (MERIS) satellite data. This study compares sea ice albedo and MPF to surface air temperature reanalysis data, compares MPF retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS), and examines albedo and MPF trends. Weekly averages of MPF for 2007 and 2011 showed different MPF dynamics while summer sea ice minimum was similar for both years. The gridded MPF and albedo products compare well to independent reanalysis temperature data and show melt onset when the temperature gets above zero; however MPD shows an offset at low MPFs of about 10 % most probably due to unscreened high clouds. Weekly averaged trends show pronounced dynamics of both, MPF and albedo: a negative MPF trend in the East Siberian Sea and a positive MPF trend around the Queen Elizabeth Islands. The negative MPF trend appears due to a change of the absolute MPF value in its peak, whereas the positive MPF trend is created by the earlier melt onset, with the peak MPF values unchanged. The MPF dynamics in the East Siberian Sea could indicate a temporal change of ice type prevailing in the region, as opposed to the Queen Elizabeth Islands, where MPF dynamics react to an earlier seasonal onset of melt.

Description: Melt pond fraction and spectral sea ice albedo retrieval from MERIS data – Part 1: Validation against in situ, aerial, and ship cruise data The Cryosphere, 9, 1551-1566, 2015 Author(s): L. Istomina, G. Heygster, M. Huntemann, P. Schwarz, G. Birnbaum, R. Scharien, C. Polashenski, D. Perovich, E. Zege, A. Malinka, A. Prikhach, and I. Katsev The presence of melt ponds on the Arctic sea ice strongly affects the energy balance of the Arctic Ocean in summer. It affects albedo as well as transmittance through the sea ice, which has consequences for the heat balance and mass balance of sea ice. An algorithm to retrieve melt pond fraction and sea ice albedo from Medium Resolution Imaging Spectrometer (MERIS) data is validated against aerial, shipborne and in situ campaign data. The results show the best correlation for landfast and multiyear ice of high ice concentrations. For broadband albedo, R 2 is equal to 0.85, with the RMS (root mean square) being equal to 0.068; for the melt pond fraction, R 2 is equal to 0.36, with the RMS being equal to 0.065. The correlation for lower ice concentrations, subpixel ice floes, blue ice and wet ice is lower due to ice drift and challenging for the retrieval surface conditions. Combining all aerial observations gives a mean albedo RMS of 0.089 and a mean melt pond fraction RMS of 0.22. The in situ melt pond fraction correlation is R 2 = 0.52 with an RMS = 0.14. Ship cruise data might be affected by documentation of varying accuracy within the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol, which may contribute to the discrepancy between the satellite value and the observed value: mean R 2 = 0.044, mean RMS = 0.16. An additional dynamic spatial cloud filter for MERIS over snow and ice has been developed to assist with the validation on swath data.

Description: Evaluation of the updated regional climate model RACMO2.3: summer snowfall impact on the Greenland Ice Sheet The Cryosphere, 9, 1831-1844, 2015 Author(s): B. Noël, W. J. van de Berg, E. van Meijgaard, P. Kuipers Munneke, R. S. W. van de Wal, and M. R. van den Broeke We discuss Greenland Ice Sheet (GrIS) surface mass balance (SMB) differences between the updated polar version of the RACMO climate model (RACMO2.3) and the previous version (RACMO2.1). Among other revisions, the updated model includes an adjusted rainfall-to-snowfall conversion that produces exclusively snowfall under freezing conditions; this especially favours snowfall in summer. Summer snowfall in the ablation zone of the GrIS has a pronounced effect on melt rates, affecting modelled GrIS SMB in two ways. By covering relatively dark ice with highly reflective fresh snow, these summer snowfalls have the potential to locally reduce melt rates in the ablation zone of the GrIS through the snow-albedo-melt feedback. At larger scales, SMB changes are driven by differences in orographic precipitation following a shift in large-scale circulation, in combination with enhanced moisture to precipitation conversion for warm to moderately cold conditions. A detailed comparison of model output with observations from automatic weather stations, ice cores and ablation stakes shows that the model update generally improves the simulated SMB-elevation gradient as well as the representation of the surface energy balance, although significant biases remain.

Description: A macroscale mixture theory analysis of deposition and sublimation rates during heat and mass transfer in dry snow The Cryosphere, 9, 1857-1878, 2015 Author(s): A. C. Hansen and W. E. Foslien The microstructure of a dry alpine snowpack is a dynamic environment where microstructural evolution is driven by seasonal density profiles and weather conditions. Notably, temperature gradients on the order of 10–20 K m −1 , or larger, are known to produce a faceted snow microstructure exhibiting little strength. However, while strong temperature gradients are widely accepted as the primary driver for kinetic growth, they do not fully account for the range of experimental observations. An additional factor influencing snow metamorphism is believed to be the rate of mass transfer at the macroscale. We develop a mixture theory capable of predicting macroscale deposition and/or sublimation in a snow cover under temperature gradient conditions. Temperature gradients and mass exchange are tracked over periods ranging from 1 to 10 days. Interesting heat and mass transfer behavior is observed near the ground, near the surface, as well as immediately above and below dense ice crusts. Information about deposition (condensation) and sublimation rates may help explain snow metamorphism phenomena that cannot be accounted for by temperature gradients alone. The macroscale heat and mass transfer analysis requires accurate representations of the effective thermal conductivity and the effective mass diffusion coefficient for snow. We develop analytical models for these parameters based on first principles at the microscale. The expressions derived contain no empirical adjustments, and further, provide self consistent values for effective thermal conductivity and the effective diffusion coefficient for the limiting cases of air and solid ice. The predicted values for these macroscale material parameters are also in excellent agreement with numerical results based on microscale finite element analyses of representative volume elements generated from X-ray tomography.

Description: Satellite observations of changes in snow-covered land surface albedo during spring in the Northern Hemisphere The Cryosphere, 9, 1879-1893, 2015 Author(s): K. Atlaskina, F. Berninger, and G. de Leeuw Thirteen years of Moderate Resolution Imaging Spectroradiometer (MODIS) surface albedo data for the Northern Hemisphere during the spring months (March–May) were analyzed to determine temporal and spatial changes over snow-covered land surfaces. Tendencies in land surface albedo change north of 50° N were analyzed using data on snow cover fraction, air temperature, vegetation index and precipitation. To this end, the study domain was divided into six smaller areas, based on their geographical position and climate similarity. Strong differences were observed between these areas. As expected, snow cover fraction (SCF) has a strong influence on the albedo in the study area and can explain 56 % of variation of albedo in March, 76 % in April and 92 % in May. Therefore the effects of other parameters were investigated only for areas with 100 % SCF. The second largest driver for snow-covered land surface albedo changes is the air temperature when it exceeds a value between −15 and −10 °C, depending on the region. At monthly mean air temperatures below this value no albedo changes are observed. The Enhanced Vegetation Index (EVI) and precipitation amount and frequency were independently examined as possible candidates to explain observed changes in albedo for areas with 100 % SCF. Amount and frequency of precipitation were identified to influence the albedo over some areas in Eurasia and North America, but no clear effects were observed in other areas. EVI is positively correlated with albedo in Chukotka Peninsula and negatively in eastern Siberia. For other regions the spatial variability of the correlation fields is too high to reach any conclusions.

Description: Review Article: Atmospheric conditions inducing extreme precipitation over the eastern and western Mediterranean Natural Hazards and Earth System Sciences, 15, 2525-2544, 2015 Author(s): U. Dayan, K. Nissen, and U. Ulbrich This review discusses published studies of heavy rainfall events over the Mediterranean Basin, combining them in a more general picture of the dynamic and thermodynamic factors and processes that produce heavy rain storms. It distinguishes the western and eastern Mediterranean in order to point out specific regional peculiarities. The crucial moisture for developing intensive convection over these regions can be originated not only from the adjacent Mediterranean Sea but also from distant upwind sources. Transport from remote sources is usually in the mid-tropospheric layers and associated with specific features and patterns of the larger-scale circulations. The synoptic systems (tropical and extratropical) that account for most of the major extreme precipitation events and the coupling of circulation and extreme rainfall patterns are presented. Heavy rainfall over the Mediterranean Basin is caused at times in concert by several atmospheric processes working at different atmospheric scales, such as local convection, upper synoptic-scale-level troughs, and mesoscale convective systems. Under tropical air-mass intrusions, convection generated by static instability seems to play a more important role than synoptic-scale vertical motions. Locally, the occurrence of torrential rains and their intensity is dependent on factors such as temperature profiles and implied instability, atmospheric moisture, and lower-level convergence.

Description: Climate change adaptation frameworks: an evaluation of plans for coastal Suffolk, UK Natural Hazards and Earth System Sciences, 15, 2511-2524, 2015 Author(s): J. Armstrong, R. Wilby, and R. J. Nicholls This paper asserts that three principal frameworks for climate change adaptation can be recognised in the literature: scenario-led (SL), vulnerability-led (VL) and decision-centric (DC) frameworks. A criterion is developed to differentiate these frameworks in recent adaptation projects. The criterion features six key hallmarks as follows: (1) use of climate model information; (2) analysis of metrics/units; (3) socio-economic knowledge; (4) stakeholder engagement; (5) adaptation of implementation mechanisms; (6) tier of adaptation implementation. The paper then tests the validity of this approach using adaptation projects on the Suffolk coast, UK. Fourteen adaptation plans were identified in an online survey. They were analysed in relation to the hallmarks outlined above and assigned to an adaptation framework. The results show that while some adaptation plans are primarily SL, VL or DC, the majority are hybrid, showing a mixture of DC/VL and DC/SL characteristics. Interestingly, the SL/VL combination is not observed, perhaps because the DC framework is intermediate and attempts to overcome weaknesses of both SL and VL approaches. The majority (57 %) of adaptation projects generated a risk assessment or advice notes. Further development of this type of framework analysis would allow better guidance on approaches for organisations when implementing climate change adaptation initiatives, and other similar proactive long-term planning.

Description: Changing surface–atmosphere energy exchange and refreezing capacity of the lower accumulation area, West Greenland The Cryosphere, 9, 2163-2181, 2015 Author(s): C. Charalampidis, D. van As, J. E. Box, M. R. van den Broeke, W. T. Colgan, S. H. Doyle, A. L. Hubbard, M. MacFerrin, H. Machguth, and C. J. P. P. Smeets We present 5 years (2009–2013) of automatic weather station measurements from the lower accumulation area (1840 m a.s.l. – above sea level) of the Greenland ice sheet in the Kangerlussuaq region. Here, the summers of 2010 and 2012 were both exceptionally warm, but only 2012 resulted in a strongly negative surface mass budget (SMB) and surface meltwater run-off. The observed run-off was due to a large ice fraction in the upper 10 m of firn that prevented meltwater from percolating to available pore volume below. Analysis reveals an anomalously low 2012 summer-averaged albedo of 0.71 (typically ~ 0.78), as meltwater was present at the ice sheet surface. Consequently, during the 2012 melt season, the ice sheet surface absorbed 28 % (213 MJ m −2 ) more solar radiation than the average of all other years. A surface energy balance model is used to evaluate the seasonal and interannual variability of all surface energy fluxes. The model reproduces the observed melt rates as well as the SMB for each season. A sensitivity analysis reveals that 71 % of the additional solar radiation in 2012 was used for melt, corresponding to 36 % (0.64 m) of the 2012 surface lowering. The remaining 64 % (1.14 m) of surface lowering resulted from high atmospheric temperatures, up to a +2.6 °C daily average, indicating that 2012 would have been a negative SMB year at this site even without the melt–albedo feedback. Longer time series of SMB, regional temperature, and remotely sensed albedo (MODIS) show that 2012 was the first strongly negative SMB year, with the lowest albedo, at this elevation on record. The warm conditions of recent years have resulted in enhanced melt and reduction of the refreezing capacity in the lower accumulation area. If high temperatures continue, the current lower accumulation area will turn into a region with superimposed ice in coming years.

Description: Comparison of a coupled snow thermodynamic and radiative transfer model with in situ active microwave signatures of snow-covered smooth first-year sea ice The Cryosphere, 9, 2149-2161, 2015 Author(s): M. C. Fuller, T. Geldsetzer, J. Yackel, and J. P. S. Gill Within the context of developing data inversion and assimilation techniques for C-band backscatter over sea ice, snow physical models may be used to drive backscatter models for comparison and optimization with satellite observations. Such modeling has the potential to enhance understanding of snow on sea-ice properties required for unambiguous interpretation of active microwave imagery. An end-to-end modeling suite is introduced, incorporating regional reanalysis data (NARR), a snow model (SNTHERM89.rev4), and a multilayer snow and ice active microwave backscatter model (MSIB). This modeling suite is assessed against measured snow on sea-ice geophysical properties and against measured active microwave backscatter. NARR data were input to the SNTHERM snow thermodynamic model in order to drive the MSIB model for comparison to detailed geophysical measurements and surface-based observations of C-band backscatter of snow on first-year sea ice. The NARR variables were correlated to available in situ measurements with the exception of long-wave incoming radiation and relative humidity, which impacted SNTHERM simulations of snow temperature. SNTHERM snow grain size and density were comparable to observations. The first assessment of the forward assimilation technique developed in this work required the application of in situ salinity profiles to one SNTHERM snow profile, which resulted in simulated backscatter close to that driven by in situ snow properties. In other test cases, the simulated backscatter remained 4–6 dB below observed for higher incidence angles and when compared to an average simulated backscatter of in situ end-member snow covers. Development of C-band inversion and assimilation schemes employing SNTHERM89.rev4 should consider sensitivity of the model to bias in incoming long-wave radiation, the effects of brine, and the inability of SNTHERM89.Rev4 to simulate water accumulation and refreezing at the bottom and mid-layers of the snowpack. These impact thermodynamic response, brine wicking and volume processes, snow dielectrics, and thus microwave backscatter from snow on first-year sea ice.

Description: From Doktor Kurowski's Schneegrenze to our modern glacier equilibrium line altitude (ELA) The Cryosphere, 9, 2135-2148, 2015 Author(s): R. J. Braithwaite Translated into modern terminology, Kurowski suggested in 1891 that the equilibrium line altitude (ELA) of a glacier is equal to the mean altitude of the glacier when the whole glacier is in balance between accumulation and ablation. Kurowski's method has been widely misunderstood, partly due to inappropriate use of statistical terminology by later workers, and has only been tested by Braithwaite and Müller in a 1980 paper (for 32 glaciers). I now compare Kurowski's mean altitude with balanced-budget ELA calculated for 103 present-day glaciers with measured surface mass-balance data. Kurowski's mean altitude is significantly higher (at 95 % level) than balanced-budget ELA for 19 outlet and 42 valley glaciers, but not significantly higher for 34 mountain glaciers. The error in Kurowski mean altitude as a predictor of balanced-budget ELA might be due to generally lower balance gradients in accumulation areas compared with ablation areas for many glaciers, as suggested by several workers, but some glaciers have higher gradients, presumably due to precipitation increase with altitude. The relatively close agreement between balanced-budget ELA and mean altitude for mountain glaciers (mean error – 8 m with standard deviation 59 m) may reflect smaller altitude ranges for these glaciers such that there is less room for effects of different balance gradients to manifest themselves.

Description: A prognostic model of the sea-ice floe size and thickness distribution The Cryosphere, 9, 2119-2134, 2015 Author(s): C. Horvat and E. Tziperman Sea ice exhibits considerable seasonal and longer-term variations in extent, concentration, thickness, and age, and is characterized by a complex and continuously changing distribution of floe sizes and thicknesses, particularly in the marginal ice zone (MIZ). Models of sea ice used in current climate models keep track of its concentration and of the distribution of ice thicknesses, but do not account for the floe size distribution and its potential effects on air–sea exchange and sea-ice evolution. Accurately capturing sea-ice variability in climate models may require a better understanding and representation of the distribution of floe sizes and thicknesses. We develop and demonstrate a model for the evolution of the joint sea-ice floe size and thickness distribution that depends on atmospheric and oceanic forcing fields. The model accounts for effects due to multiple processes that are active in the MIZ and seasonal ice zones: freezing and melting along the lateral side and base of floes, mechanical interactions due to floe collisions (ridging and rafting), and sea-ice fracture due to wave propagation in the MIZ. The model is then examined and demonstrated in a series of idealized test cases.

Description: Winter observations of CO 2 exchange between sea ice and the atmosphere in a coastal fjord environment The Cryosphere, 9, 1701-1713, 2015 Author(s): J. Sievers, L. L. Sørensen, T. Papakyriakou, B. Else, M. K. Sejr, D. Haubjerg Søgaard, D. Barber, and S. Rysgaard Eddy covariance observations of CO 2 fluxes were conducted during March–April 2012 in a temporally sequential order for 8, 4 and 30 days, respectively, at three locations on fast sea ice and on newly formed polynya ice in a coastal fjord environment in northeast Greenland. CO 2 fluxes at the sites characterized by fast sea ice (ICEI and DNB) were found to increasingly reflect periods of strong outgassing in accordance with the progression of springtime warming and the occurrence of strong wind events: F CO 2 ICE1 = 1.73 ± 5 mmol m −2 day −1 and F CO 2 DNB = 8.64 ± 39.64 mmol m −2 day −1 , while CO 2 fluxes at the polynya site (POLYI) were found to generally reflect uptake F CO 2 POLY1 = −9.97 ± 19.8 mmol m −2 day −1 . Values given are the mean and standard deviation, and negative/positive values indicate uptake/outgassing, respectively. A diurnal correlation analysis supports a significant connection between site energetics and CO 2 fluxes linked to a number of possible thermally driven processes, which are thought to change the p CO 2 gradient at the snow–ice interface. The relative influence of these processes on atmospheric exchanges likely depends on the thickness of the ice. Specifically, the study indicates a predominant influence of brine volume expansion/contraction, brine dissolution/concentration and calcium carbonate formation/dissolution at sites characterized by a thick sea-ice cover, such that surface warming leads to an uptake of CO 2 and vice versa, while convective overturning within the sea-ice brines dominate at sites characterized by comparatively thin sea-ice cover, such that nighttime surface cooling leads to an uptake of CO 2 to the extent permitted by simultaneous formation of superimposed ice in the lower snow column.

Description: Exploring the utility of quantitative network design in evaluating Arctic sea ice thickness sampling strategies The Cryosphere, 9, 1721-1733, 2015 Author(s): T. Kaminski, F. Kauker, H. Eicken, and M. Karcher We present a quantitative network design (QND) study of the Arctic sea ice–ocean system using a software tool that can evaluate hypothetical observational networks in a variational data assimilation system. For a demonstration, we evaluate two idealised flight transects derived from NASA's Operation IceBridge airborne ice surveys in terms of their potential to improve 10-day to 5-month sea ice forecasts. As target regions for the forecasts we select the Chukchi Sea, an area particularly relevant for maritime traffic and offshore resource exploration, as well as two areas related to the Barnett ice severity index (BSI), a standard measure of shipping conditions along the Alaskan coast that is routinely issued by ice services. Our analysis quantifies the benefits of sampling upstream of the target area and of reducing the sampling uncertainty. We demonstrate how observations of sea ice and snow thickness can constrain ice and snow variables in a target region and quantify the complementarity of combining two flight transects. We further quantify the benefit of improved atmospheric forecasts and a well-calibrated model.

Description: UAV-based urban structural damage assessment using object-based image analysis and semantic reasoning Natural Hazards and Earth System Science, 15, 1087-1101, 2015 Author(s): J. Fernandez Galarreta, N. Kerle, and M. Gerke Structural damage assessment is critical after disasters but remains a challenge. Many studies have explored the potential of remote sensing data, but limitations of vertical data persist. Oblique imagery has been identified as more useful, though the multi-angle imagery also adds a new dimension of complexity. This paper addresses damage assessment based on multi-perspective, overlapping, very high resolution oblique images obtained with unmanned aerial vehicles (UAVs). 3-D point-cloud assessment for the entire building is combined with detailed object-based image analysis (OBIA) of façades and roofs. This research focuses not on automatic damage assessment, but on creating a methodology that supports the often ambiguous classification of intermediate damage levels, aiming at producing comprehensive per-building damage scores. We identify completely damaged structures in the 3-D point cloud, and for all other cases provide the OBIA-based damage indicators to be used as auxiliary information by damage analysts. The results demonstrate the usability of the 3-D point-cloud data to identify major damage features. Also the UAV-derived and OBIA-processed oblique images are shown to be a suitable basis for the identification of detailed damage features on façades and roofs. Finally, we also demonstrate the possibility of aggregating the multi-perspective damage information at building level.

Description: Constraints on the δ 2 H diffusion rate in firn from field measurements at Summit, Greenland The Cryosphere, 9, 1089-1103, 2015 Author(s): L. G. van der Wel, H. A. Been, R. S. W. van de Wal, C. J. P. P. Smeets, and H. A. J. Meijer We performed detailed 2 H isotope diffusion measurements in the upper 3 m of firn at Summit, Greenland. Using a small snow gun, a thin snow layer was formed from 2 H-enriched water over a 6 × 6 m 2 area. We followed the diffusion process, quantified as the increase of the δ 2 H diffusion length, over a 4-year period, by retrieving the layer once per year by drilling a firn core and slicing it into 1 cm layers and measuring the δ 2 H signal of these layers. We compared our experimental findings to calculations based on the model by Johnsen et al. (2000) and found substantial differences. The diffusion length in our experiments increased much less over the years than in the model. We discuss the possible causes for this discrepancy and conclude that several aspects of the diffusion process in firn are still poorly constrained, in particular the tortuosity.

Description: Effects of soil settlement and deformed geometry on a historical structure Natural Hazards and Earth System Science, 15, 1051-1059, 2015 Author(s): Y. Yardım and E. Mustafaraj Protecting the historical character of a valued structure during the assessment and damage repair process is a very challenging task for many engineers. Heritage protection is complicated by a lack of design details and restrictions on sample extraction needed to obtain accurate material properties and limited studies on the restoration of certain types of historical structures. This study aims to assess the effects of soil settlement on a structure's stress concentrations and the value of laser scanning techniques on structure analysis in obtaining correct data of settlement vs. deformation. Terrestrial laser scanner (TLS) data are used to analyse the 500-year-old historical structure of Naziresha's Mosque. The obtained TLS data allow an accurate definition of the imperfect geometry patterns lying on every side of the structure. The soil profile and general crack formation together with TLS measurement proves that the structure deformed toward the south façade, where a railway and motorway are also located. Stress concentration and mode period results have a considerable difference, which highlights earthquake vulnerability and failure mechanisms and changes the strategy of possible retrofitting.

Description: On a report that the 2012 M 6.0 earthquake in Italy was predicted after seeing an unusual cloud formation Natural Hazards and Earth System Science, 15, 1061-1068, 2015 Author(s): J. N. Thomas, F. Masci, and J. J. Love Several recently published reports have suggested that semi-stationary linear-cloud formations might be causally precursory to earthquakes. We examine the report of Guangmeng and Jie (2013), who claim to have predicted the 2012 M 6.0 earthquake in the Po Valley of northern Italy after seeing a satellite photograph (a digital image) showing a linear-cloud formation over the eastern Apennine Mountains of central Italy. From inspection of 4 years of satellite images we find numerous examples of linear-cloud formations over Italy. A simple test shows no obvious statistical relationship between the occurrence of these cloud formations and earthquakes that occurred in and around Italy. All of the linear-cloud formations we have identified in satellite images, including that which Guangmeng and Jie (2013) claim to have used to predict the 2012 earthquake, appear to be orographic – formed by the interaction of moisture-laden wind flowing over mountains. Guangmeng and Jie (2013) have not clearly stated how linear-cloud formations can be used to predict the size, location, and time of an earthquake, and they have not published an account of all of their predictions (including any unsuccessful predictions). We are skeptical of the validity of the claim by Guangmeng and Jie (2013) that they have managed to predict any earthquakes.

Description: Air temperature variability over three glaciers in the Ortles–Cevedale (Italian Alps): effects of glacier fragmentation, comparison of calculation methods, and impacts on mass balance modeling The Cryosphere, 9, 1129-1146, 2015 Author(s): L. Carturan, F. Cazorzi, F. De Blasi, and G. Dalla Fontana Glacier mass balance models rely on accurate spatial calculation of input data, in particular air temperature. Lower temperatures (the so-called glacier cooling effect) and lower temperature variability (the so-called glacier damping effect) generally occur over glaciers compared to ambient conditions. These effects, which depend on the geometric characteristics of glaciers and display a high spatial and temporal variability, have been mostly investigated on medium to large glaciers so far, while observations on smaller ice bodies ( 〈 0.5 km 2 ) are scarce. Using a data set from eight on-glacier and four off-glacier weather stations, collected in the summers of 2010 and 2011, we analyzed the air temperature variability and wind regime over three different glaciers in the Ortles–Cevedale. The magnitude of the cooling effect and the occurrence of katabatic boundary layer (KBL) processes showed remarkable differences among the three ice bodies, suggesting the likely existence of important reinforcing mechanisms during glacier decay and fragmentation. The methods proposed by Greuell and Böhm (1998) and Shea and Moore (2010) for calculating on-glacier temperature from off-glacier data did not fully reproduce our observations. Among them, the more physically based procedure of Greuell and Böhm (1998) provided the best overall results where the KBL prevails, but it was not effective elsewhere (i.e., on smaller ice bodies and close to the glacier margins). The accuracy of air temperature estimations strongly impacted the results from a mass balance model which was applied to the three investigated glaciers. Most importantly, even small temperature deviations caused distortions in parameter calibration, thus compromising the model generalizability.

Description: Changes in the firn structure of the western Greenland Ice Sheet caused by recent warming The Cryosphere, 9, 1203-1211, 2015 Author(s): S. de la Peña, I. M. Howat, P. W. Nienow, M. R. van den Broeke, E. Mosley-Thompson, S. F. Price, D. Mair, B. Noël, and A. J. Sole Atmospheric warming over the Greenland Ice Sheet during the last 2 decades has increased the amount of surface meltwater production, resulting in the migration of melt and percolation regimes to higher altitudes and an increase in the amount of ice content from refrozen meltwater found in the firn above the superimposed ice zone. Here we present field and airborne radar observations of buried ice layers within the near-surface (0–20 m) firn in western Greenland, obtained from campaigns between 1998 and 2014. We find a sharp increase in firn-ice content in the form of thick widespread layers in the percolation zone, which decreases the capacity of the firn to store meltwater. The estimated total annual ice content retained in the near-surface firn in areas with positive surface mass balance west of the ice divide in Greenland reached a maximum of 74 ± 25 Gt in 2012, compared to the 1958–1999 average of 13 ± 2 Gt, while the percolation zone area more than doubled between 2003 and 2012. Increased melt and column densification resulted in surface lowering averaging −0.80 ± 0.39 m yr −1 between 1800 and 2800 m in the accumulation zone of western Greenland. Since 2007, modeled annual melt and refreezing rates in the percolation zone at elevations below 2100 m surpass the annual snowfall from the previous year, implying that mass gain in the region is retained after melt in the form of refrozen meltwater. If current melt trends over high elevation regions continue, subsequent changes in firn structure will have implications for the hydrology of the ice sheet and related abrupt seasonal densification could become increasingly significant for altimetry-derived ice sheet mass balance estimates.

Description: Land cover changes and forest landscape evolution (1985–2009) in a typical Mediterranean agroforestry system (high Agri Valley) Natural Hazards and Earth System Science, 15, 1201-1214, 2015 Author(s): T. Simoniello, R. Coluzzi, V. Imbrenda, and M. Lanfredi The present study focuses on the transformations of a typical Mediterranean agroforestry landscape of southern Italy (high Agri Valley – Basilicata region) that occurred over 24 years. In this period, the valuable agricultural and natural areas that compose such a landscape were subjected to intensive industry-related activities linked to the exploitation of the largest European onshore oil reservoir. Landsat imagery acquired in 1985 and 2009 were used to detect changes in forest areas and major land use trajectories. Landscape metrics indicators were adopted to characterize landscape structure and evolution of both the complex ecomosaic (14 land cover classes) and the forest/non-forest arrangement. Our results indicate a net increase of 11% of forest areas between 1985 and 2009. The major changes concern increase of all forest covers at the expense of pastures and grasses, enlargement of riparian vegetation, and expansion of artificial areas. The observed expansion of forests was accompanied by a decrease of the fragmentation levels likely due to the reduction of small glades that break forest homogeneity and to the recolonization of herbaceous areas. Overall, we observe an evolution towards a more stable configuration depicting a satisfactory picture of vegetation health.

Description: Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash-flood deposits Natural Hazards and Earth System Science, 15, 1181-1199, 2015 Author(s): D. Sakuna-Schwartz, P. Feldens, K. Schwarzer, S. Khokiattiwong, and K. Stattegger Tsunami, storm and flash-flood event layers, which have been deposited over the last century on the shelf offshore Khao Lak (Thailand, Andaman Sea), are identified in sediment cores based on sedimentary structures, grain size compositions, Ti / Ca ratios and 210 Pb activity. Individual offshore tsunami deposits are 12 to 30 cm in thickness and originate from the 2004 Indian Ocean Tsunami. They are characterized by (1) the appearance of sand layers enriched in shells and shell debris and (2) the appearance of mud and sand clasts. Storm deposits found in core depths between 5 and 82 cm could be attributed to recent storm events by using 210 Pb profiles in conjunction with historical data of typhoons and tropical storms. Massive sand layers enriched in shells and shell debris characterize storm deposits. The last classified type of event layer represents reworked flash-flood deposits, which are characterized by a fining-upward sequence of muddy sediment. The most distinct difference between storm and tsunami deposits is the lack of mud and sand clasts, mud content and terrigenous material within storm deposits. Terrigenous material transported offshore during the tsunami backwash is therefore an important indicator to distinguish between storm and tsunami deposits in offshore environments.

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: Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding Agnieszka Indiana Olbert, Joanne Comer, Stephen Nash, and Michael Hartnett Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-238,2016 Manuscript under review for NHESS (discussion: open, 0 comments) A novel nested flood model (MSN_Flood) is applied to simulate complex coastal-fluvial urban flooding in order to critically examine the model's capability to forecast evolution of urban inundation. The model demonstrates high accuracy of outputs without incurring the computational expense of high spatial resolution over the entire model domain. MSN_Flood provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

Description: Comparison and validation of global and regional ocean forecasting systems for the South China Sea Xueming Zhu, Hui Wang, Guimei Liu, Charly Régnier, Xiaodi Kuang, Dakui Wang, Shihe Ren, Zhiyou Jing, and Marie Drévillon Nat. Hazards Earth Syst. Sci., 16, 1639-1655, doi:10.5194/nhess-16-1639-2016, 2016 This paper examined the performances of two operational ocean forecasting systems, Mercator Océan in France and SCSOFS in China, based on observed satellite and in situ data obtained in 2012. The comparison and validation are focused on the ocean circulations, the structures of temperature and salinity, and some mesoscale activities in the South China Sea. Finally, some recommendations have been proposed for both systems to improve their performances in the near future.

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: 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: 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: Enhancing local action planning through quantitative flood risk analysis: a case study in Spain Jesica Tamara Castillo-Rodríguez, Ignacio Escuder-Bueno, Sara Perales-Momparler, and Juan Ramón Porta-Sancho Nat. Hazards Earth Syst. Sci., 16, 1699-1718, doi:10.5194/nhess-16-1699-2016, 2016 This article presents a method to incorporate and promote quantitative flood risk analysis to support local action planning against flooding. The conducted research work aims at providing a framework for local flood risk analysis and to support risk-informed decision-making (e.g. urban planning and development, flood risk management, civil protection). This article shows the added value of a risk-informed perspective, applied to a real case study in Spain.

Description: Meteorological factors driven glacial till changing and the associated periglacial debris flows in Tianmo Valley, southeast Tibetan Plateau Mingfeng Deng, Ningsheng Chen, and Mei Liu Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-251,2016 Manuscript under review for NHESS (discussion: open, 0 comments) Initiation of deris flows in Tianmo valley shows annual temperature spiked and glacier retreat quickly before the three debris flows, while they did not occur when glacier retreat is sharpest, resulting from the bared glacial till is frozen as the melting of internal ice lags behind glacial retreat. The activity of the glacial till can be enhanced by prolonged high air temperature. Finally, either rainfall or continuous percolation of ice ablation water flows can generate periglacial debris flows.

Description: Analysis of slope processes in the Vallcebre landslide (Eastern Pyrenees, Spain) by means of Cross Correlation Function applied to high frequency monitoring data Marco Mulas, Jordi Corominas, Alessandro Corsini, and Jose Moya Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-253,2016 Manuscript under review for NHESS (discussion: open, 0 comments) In this work, the Cross-Correlation Function is used in order to quantitatively investigate the time-lagged correlation between high frequency monitoring data on rainfall, piezometric and displacement with the objective to evidence hydro-mechanical processes in the Vallcebre landslide (Eastern Pyrenees, Spain). The analysis highlighted and constrained in time a dual triggering mechanism in which factors controlling movement change from the upper to the lower part of the landslide.

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: Vulnerability curves vs. vulnerability indicators: application of an indicator-based methodology for debris-flow hazards Maria Papathoma-Köhle Nat. Hazards Earth Syst. Sci., 16, 1771-1790, doi:10.5194/nhess-16-1771-2016, 2016 Two established methods for assessing the physical vulnerability of buildings to natural hazards (vulnerability indicators and vulnerability curves) are compared after beind applied at the same case study. The case study area is located in South Tyrol (Italy) and it is subject to debris flow hazard. The results indicate that both methods have advantages and disadvantages and should be used in combination rather than in isolation by practitioners.

Description: What if the 25 October 2011 event that struck Cinque Terre (Liguria) had happened in Genoa, Italy? Flooding scenarios, hazard mapping and damage estimation Francesco Silvestro, Nicola Rebora, Lauro Rossi, Daniele Dolia, Simone Gabellani, Flavio Pignone, Eva Trasforini, Roberto Rudari, Silvia De Angeli, and Cristiano Masciulli Nat. Hazards Earth Syst. Sci., 16, 1737-1753, doi:10.5194/nhess-16-1737-2016, 2016 During the autumn of 2011 two catastrophic, very intense rainfall events affected two different parts of the Liguria Region of Italy causing various flash floods. The first occurred in October and the second at the beginning of November. Both the events were characterized by very high rainfall intensities (〉 100 mm h −1 ) that persisted on a small portion of territory causing local huge rainfall accumulations (〉 400 mm 6 h −1 ). Two main considerations were made in order to set up this work. The first consideration is that various studies demonstrated that the two events had a similar genesis and similar triggering elements. The second very evident and coarse concern is that two main elements are needed to have a flash flood: a very intense and localized rainfall event and a catchment (or a group of catchments) to be affected. Starting from these assumptions we did the exercise of mixing the two flash flood ingredients by putting the rainfall field of the first event on the main catchment struck by the second event, which has its mouth in the biggest city of the Liguria Region: Genoa. A complete framework was set up to quantitatively carry out a “what if” experiment with the aim of evaluating the possible damages associated with this event. A probabilistic rainfall downscaling model was used to generate possible rainfall scenarios maintaining the main characteristics of the observed rainfall fields while a hydrological model transformed these rainfall scenarios in streamflow scenarios. A subset of streamflow scenarios is then used as input to a 2-D hydraulic model to estimate the hazard maps, and finally a proper methodology is applied for damage estimation. This leads to the estimation of the potential economic losses and of the risk level for the people that stay in the affected area. The results are interesting, surprising and in a way worrying: a rare but not impossible event (it occurred about 50 km away from Genoa) would have caused huge damages estimated between 120 and EUR 230 million for the affected part of the city of Genoa, Italy, and more than 17 000 potentially affected people.

Description: VISIR: technological infrastructure of an operational service for safe and efficient navigation in the Mediterranean Sea Gianandrea Mannarini, Giuseppe Turrisi, Alessandro D'Anca, Mario Scalas, Nadia Pinardi, Giovanni Coppini, Francesco Palermo, Ivano Carluccio, Matteo Scuro, Sergio Cretì, Rita Lecci, Paola Nassisi, and Luca Tedesco Nat. Hazards Earth Syst. Sci., 16, 1791-1806, doi:10.5194/nhess-16-1791-2016, 2016 Safety and efficiency of navigation can be enhanced through a better situational awareness at sea. We designed and realized an operational infrastructure for providing the navigators with optimal routes through various devices: PC, tablets, and smartphones. Sea-state and wind forecasts are used as inputs. Both motor- and sailboat routes are addressed by VISIR.

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: Brief Communication: An update of the article "Modelling flood damages under climate change conditions – a case study for Germany" Fred Fokko Hattermann, Shaochun Huang, Olaf Burghoff, Peter Hoffmann, and Zbigniew W. Kundzewicz Nat. Hazards Earth Syst. Sci., 16, 1617-1622, doi:10.5194/nhess-16-1617-2016, 2016 We report that a considerable increase in flood-related losses can be expected in Germany in a future warmer climate. The general significance of the study is supported by the fact that the outcome of an ensemble of global climate models (GCMs) and regional climate models (RCMs) was used as a climate driver for a hydrological model considering more than 3000 river basins in Germany.

Description: Mangrove forest against dyke-break-induced tsunami on rapidly subsiding coasts Hiroshi Takagi, Takahito Mikami, Daisuke Fujii, Miguel Esteban, and Shota Kurobe Nat. Hazards Earth Syst. Sci., 16, 1629-1638, doi:10.5194/nhess-16-1629-2016, 2016 Thin coastal dykes found in developing countries may suddenly collapse due to land subsidence, material ageing, earthquakes, a collision with vessels, etc. Such a failure could trigger a dyke-break-induced tsunami. To analyse the potential consequences of such a flooding event, a hydrodynamic model was created using the data from the authors' field surveys of a vulnerable coastal community in Jakarta. The countermeasure of using mangrove forest is also proposed to mitigate violent floods.

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: Debris flow impact estimation on a rigid barrier Federico Vagnon and Andrea Segalini Nat. Hazards Earth Syst. Sci., 16, 1691-1697, doi:10.5194/nhess-16-1691-2016, 2016 This study has the aim of reviewing the dynamics of debris flow impact against rigid structures and providing a new simple formulation to predict peak thrust. The proposed equation differs from other formulations because it takes into account flow characteristics, material properties, and barrier dimensions. The developed model is sufficiently capable of predicting measured force during the laboratory tests.

Description: Using video games for volcanic hazard education and communication: an assessment of the method and preliminary results Lara Mani, Paul D. Cole, and Iain Stewart Nat. Hazards Earth Syst. Sci., 16, 1673-1689, doi:10.5194/nhess-16-1673-2016, 2016 Here, we aim to better understand the potential for using video games in volcanic hazard education with at-risk communities. A study using a bespoke-designed video game – St. Vincent's Volcano – was trialled on the Caribbean island of St. Vincent in 2015. Preliminary data analysis demonstrates 94 % of study participants had an improved knowledge of volcanic hazards after playing the game, leading us to conclude that video games could be a logical progression for education and outreach activities.

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: Simple and approximate upper-limit estimation of future precipitation return-values Rasmus E. Benestad, Kajsa M. Parding, Abdelkader Mezghani, and Anita V. Dyrrdal Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-229,2016 Manuscript under review for NHESS (discussion: open, 0 comments) We propose a strategy for quantifying the maximum effect a temperature change has on heavy precipitation amounts making use of the limited available sources of information: laws of physics, seasonal variations, mathematical estimation of probability, and large number of climate model results. An upper bound is estimated rather than most likely value.

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: Partial reactivation of a huge deep-seated ancient rock slide: recognition, formation mechanism, and stability Minggao Tang, Qiang Xu, Yusheng Li, Runqiu Huang, Niek Rengers, and Xing Zhu Nat. Hazards Earth Syst. Sci., 16, 1719-1735, doi:10.5194/nhess-16-1719-2016, 2016 An important argument for the conclusion is the recognition of a regional compressive tectonic stress field in this area, which cannot lead to the formation of a fault graben, which needs a tensional tectonic stress field. Moreover, numerous unique geological features, sliding marks, and other relics of the ancient slide have been discovered in the field. A centrifuge model test shows that a deformation and failure process of "creep–crack–cut" and a type of "successive rotational rock slide" have occurred.

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: Lightning risk assessment at a high spatial resolution using the resident sub-district scale: A case study in Beijing metropolitan areas Hai Bo Hu and Jing Xiao Li Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-231,2016 Manuscript under review for NHESS (discussion: open, 0 comments) Lightning risk indexes identifying the potential number of dangerous lightning events (NDLEs) and ground sensitivity to lightning in resident sub-districts of Beijing metropolitan areas have been unprecedentedly estimated on a 5 m resolution grid. The gridded cloud to ground (CG) lightning stroke density was used in the NDLE calculation, on account of multiple contacts formed by CG lightning flash multiplicity. Meanwhile, in the NDLE estimates, the critical CG stroke gridded densities derived from the lightning location system (LLS) data were corrected for network detection efficiency (DE). This case study on resident sub-district indicates that the site-specific sensitivity to lightning, which is determined by the terrain factors related to lightning attachment, as well as lightning rod effects induced by nearby structures, differs greatly across types of underlying ground areas. The discrepancy of the NDLE which is the numerical product of sensitivity and CG stroke density, is predominated by the sensitivity on account of the relatively stationary CG stroke density in a resident sub-district scale. Conclusively, the visualization of lightning risk sensitivity and NDLE discrepancy in parts of a resident sub-district at high spatial resolution makes it convenient in risk reduction and risk control for lightning risk management.

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: The unrest of the San Miguel volcano (El Salvador, Central America): installation of the monitoring network and observed volcano-tectonic ground deformation Alessandro Bonforte, Douglas Antonio Hernandez, Eduardo Gutiérrez, Louis Handal, Cecilia Polío, Salvatore Rapisarda, and Piergiorgio Scarlato Nat. Hazards Earth Syst. Sci., 16, 1755-1769, doi:10.5194/nhess-16-1755-2016, 2016 In this paper, we present the work done during an international cooperation between Italy and El Salvador, for implementing the multiparametric monitoring of the San Miguel volcano in El Salvador after its sudden unrest. In particular, the aim of this paper is to show and describe the installed geodetic network and to show, comment and interpret the very first detailed ground deformation data obtained on this volcano during an unrest period, useful for characterizing its unknown dynamics.

Description: Hydrodynamic modelling of coastal seas: the role of tidal dynamics in the Messina Strait, Western Mediterranean Sea Andrea Cucco, Giovanni Quattrocchi, Antonio Olita, Leopoldo Fazioli, Alberto Ribotti, Matteo Sinerchia, Costanza Tedesco, and Roberto Sorgente Nat. Hazards Earth Syst. Sci., 16, 1553-1569, doi:10.5194/nhess-16-1553-2016, 2016 This work explored the importance of considering the tidal dynamics when modelling the general circulation in the Messina Strait, a narrow passage connecting the Tyrrhenian and the Ionian Sea sub-basins in the Western Mediterranean Sea. The results highlight that tidal dynamics deeply impact the reproduction of the instantaneous and residual circulation pattern, waters thermohaline properties and transport dynamics both inside the Messina Strait and in the surrounding coastal and open waters.

Description: Heavy snow loads in Finnish forests respond regionally asymmetrically to projected climate change Ilari Lehtonen, Matti Kämäräinen, Hilppa Gregow, Ari Venäläinen, and Heli Peltola Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-184,2016 Manuscript under review for NHESS (discussion: open, 0 comments) We studied the impact of projected climate change on the risk of snow-induced forest damage in Finland. Although winters are projected to become milder over the whole of Finland, our results suggest than in eastern and northern Finland the risk may increase while in southern and western parts of the country it is projected to decrease. This indicates that there is increasing need to consider the potential of snow damage in forest management in eastern and northern Finland.

Description: Review article: Potential application of surface methods for the monitoring of organic matter dynamics in marine systems Galja Pletikapić and Nadica Ivošević DeNardis Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-178,2016 Manuscript under review for NHESS (discussion: open, 0 comments) We present the potential of non-invasive surface methods, the electrochemical method applied with atomic force microscopy imaging (AFM), and its application for monitoring needs undertaken in the Adriatic sea. Electrochemical approach enables simple and fast analysis of a large number of raw seawater samples due to the simultaneous differentiation of organic constituents in seawater. AFM allows direct visualization and structural organization of marine organic matter at nanometer scales.

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: GPS-derived ground deformation (2005–2014) within the Gulf of Mexico region referred to a stable Gulf of Mexico reference frame Jiangbo Yu and Guoquan Wang Nat. Hazards Earth Syst. Sci., 16, 1583-1602, doi:10.5194/nhess-16-1583-2016, 2016 The study establishes the first local reference frame for the Gulf of Mexico region using the observations from 13 GNSS sites. The root mean square (RMS) of the velocities of the 13 reference stations achieves 0.2 mm yr −1 in the horizontal and 0.3 mm yr −1 in the vertical directions. Land subsidence, faulting, and salt dome activities in the Houston region, Mexico City, and the southeastern Louisiana region are discussed and compared.

Description: GIS analysis of effects of future Baltic sea level rise on the island of Gotland, Sweden Karin Ebert, Karin Ekstedt, and Jerker Jarsjö Nat. Hazards Earth Syst. Sci., 16, 1571-1582, doi:10.5194/nhess-16-1571-2016, 2016 Future sea level rise is inevitable. We investigate the effects of 2 m sea level rise on the island of Gotland, Sweden. In a multi-criteria analysis we analyze the quantity of infrastructure that will be inundated, and the effect of saltwater intrusion in wells. Almost 100 km 2 (3 %) of Gotland's land area will be inundated. Important touristic and nature values will be strongest affected. Well salinization will greatly increase. Administrative planning is needed to prepare for changes.

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: TESSA: design and implementation of a platform for Situational Sea Awareness M. Scalas, P. Marra, L. Tedesco, R. Quarta, E. Cantoro, A. Tumolo, D. Rollo, and M. Spagnulo Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-166,2016 Manuscript under review for NHESS (discussion: open, 0 comments) This article describes the architecture of Sea Situational Awareness (SSA) platform, a major asset within "TESSA", an industrial research project funded by the Italian Ministry of Education and Research. The main aim of the platform is to collect, transform and provide forecast and observational data as information suitable for delivery across a variety of channels, like web and mobile; specifically, the ability to produce and provide forecast information suitable for creating SSA-enabled applications has been a critical driving factor when designing and evolving the whole architecture. Thus, starting from functional and performance requirements, the platform architecture is described in terms of its main building blocks and flows among them: front-end components that support end-user applications and map and data analysis components that allow for serving maps and querying data. Focus is directed to key aspects and decisions about the main issues faced, like interoperability, scalability, efficiency and adaptability, but it also considers insights about future works in this and similarly related subjects. Some analysis results are also provided in order to better characterize critical issues and related solutions.

Description: Hydrodynamic characterization of past flash-flood events and their associated hazards from dendrogeomorphological evidence in Caldera de Taburiente National Park (Canary Islands, Spain) Julio Garrote, Andrés Diez-Herrero, José M. Bodoque, María A. Perucha, Pablo Mayer, and Mar Genova Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-206,2016 Manuscript under review for NHESS (discussion: open, 0 comments) The paper shows a study assessing different flooding scenarios based on the height of scars in trees as indicators for peak discharge estimation in an ungauged fluvial basin with sand and gravel riverbed. The use of scars on trees together with the combined use of 2D hydraulic model and LIDAR topographic data, has allowed a better peak discharge estimation of January, 11–13, 1997 flash flood and its related hazards, than estimation from rainfall data. This could improve flooding risk mapping.

Description: Brief communication "Loss and Damage from a catastrophic landslide in Nepal" Kees van der Geest and Markus Schindler Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-210,2016 Manuscript under review for NHESS (discussion: open, 0 comments) In August 2014, a major landslide struck in a densely populated district 80 km northeast of Nepal's capital Kathmandu, in Sindhupalchok District. This study combines evidence from surveyes and intereviews to assess impacts, and preventive and coping measures taken. The impacts relative to annual income show that the poor lost up to 14 times their annual income, as opposed to 3 times for the non-poor. The implications of these findings for discussions surrounding loss and damage are discussed.