bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing the performance of regional landslide early warning models: the EDuMaP method
Authors: Calvello M. , Piciullo L. 
Published: January 2016

Abstract. A schematic of the components of regional early warning systems for rainfall-induced landslides is herein proposed, based on a clear distinction between warning models and warning systems. According to this framework an early warning system comprises a warning model as well as a monitoring and warning strategy, a communication strategy and an emergency plan. The paper proposes the evaluation of regional landslide warning models by means of an original approach, called the "event, duration matrix, performance" (EDuMaP) method, comprising three successive steps: identification and analysis of the events, i.e., landslide events and warning events derived from available landslides and warnings databases; definition and computation of a duration matrix, whose elements report the time associated with the occurrence of landslide events in relation to the occurrence of warning events, in their respective classes; evaluation of the early warning model performance by means of performance criteria and indicators applied to the duration matrix. During the first step the analyst identifies and classifies the landslide and warning events, according to their spatial and temporal characteristics, by means of a number of model parameters. In the second step, the analyst computes a time-based duration matrix with a number of rows and columns equal to the number of classes defined for the warning and landslide events, respectively. In the third step, the analyst computes a series of model performance indicators derived from a set of performance criteria, which need to be defined by considering, once again, the features of the warning model. The applicability, potentialities and limitations of the EDuMaP method are tested and discussed using real landslides and warning data from the municipal early warning system operating in Rio de Janeiro (Brazil).
Effective 3-D surface modeling for geographic information systems
Authors: Yüksek K. , Alparslan M. , Mendi E. 
Published: January 2016

Abstract. In this work, we propose a dynamic, flexible and interactive urban digital terrain platform with spatial data and query processing capabilities of geographic information systems, multimedia database functionality and graphical modeling infrastructure. A new data element, called Geo-Node, which stores image, spatial data and 3-D CAD objects is developed using an efficient data structure. The system effectively handles data transfer of Geo-Nodes between main memory and secondary storage with an optimized directional replacement policy (DRP) based buffer management scheme. Polyhedron structures are used in digital surface modeling and smoothing process is performed by interpolation. The experimental results show that our framework achieves high performance and works effectively with urban scenes independent from the amount of spatial data and image size. The proposed platform may contribute to the development of various applications such as Web GIS systems based on 3-D graphics standards (e.g., X3-D and VRML) and services which integrate multi-dimensional spatial information and satellite/aerial imagery.
PM10 measurements in urban settlements after lava fountain episodes at Mt. Etna, Italy: pilot test to assess volcanic ash hazard to human health
Authors: Andronico D. , Del Carlo P. 
Published: January 2016

Abstract. We have carried out a preliminary study on the potential risks caused by the sub-10 µm fraction of volcanic ash (particulate matter, PM10) after the basaltic explosive eruptions from Mt. Etna volcano (Italy), which have dramatically increased in frequency over the last 20 years. We present results deriving from the study of the ash concentration in the air following the lava fountain episode from the New Southeast Crater of Etna on 15 November 2011, which caused tephra fallout over the eastern slope of the volcano. Short-duration tests of PM10 measurements were carried out at three different sites using a TSI® DustTrakTM aerosol monitor a few hours after the end of the eruption, and readouts of the air quality were repeated at the same sites a month later without volcanic activity. Furthermore, ash samples were characterized by grain size, componentry and morphological and petrochemical analyses. By comparing PM10 levels measured a few hours after the 15 November lava fountain and on 15 December, we found that relatively low amounts (500–1500 g m−2) of tephra fallout cause high levels of PM10 in the air. This is because the coarse particles, particularly basaltic ash, are readily broken up by traffic and hence remobilized into the air. We believe the impact from ash fallout in the Etnean territory should receive greater attention, especially regarding potential health problems. Simple but effective actions can be implemented to reduce eventual risks, first and foremost the prompt removal of the ash deposits from the urbanized areas.
Investigation of model capability in capturing vertical hydrodynamic coastal processes: a case study in the north Adriatic Sea
Authors: McKiver W. J. , Sannino G. , Braga F. , Bellafiore D. 
Published: January 2016

Abstract. In this work we consider a numerical study of hydrodynamics in the coastal zone using two different models, SHYFEM (shallow water hydrodynamic finite element model) and MITgcm (Massachusetts Institute of Technology general circulation model), to assess their capability to capture the main processes. We focus on the north Adriatic Sea during a strong dense water event that occurred at the beginning of 2012. This serves as an interesting test case to examine both the models strengths and weaknesses, while giving an opportunity to understand how these events affect coastal processes, like upwelling and downwelling, and how they interact with estuarine dynamics. Using the models we examine the impact of setup, surface and lateral boundary treatment, resolution and mixing schemes, as well as assessing the importance of nonhydrostatic dynamics in coastal processes. Both models are able to capture the dense water event, though each displays biases in different regions. The models show large differences in the reproduction of surface patterns, identifying the choice of suitable bulk formulas as a central point for the correct simulation of the thermohaline structure of the coastal zone. Moreover, the different approaches in treating lateral freshwater sources affect the vertical coastal stratification. The results indicate the importance of having high horizontal resolution in the coastal zone, specifically in close proximity to river inputs, in order to reproduce the effect of the complex coastal morphology on the hydrodynamics. A lower resolution offshore is acceptable for the reproduction of the dense water event, even if specific vortical structures are missed. Finally, it is found that nonhydrostatic processes are of little importance for the reproduction of dense water formation in the shelf of the north Adriatic Sea.
Virtual radar ice buoys – a method for measuring fine-scale sea ice drift
Authors: Karvonen J. 
Published: January 2016

Abstract. Here we present an algorithm for continuous ice drift estimation based on coastal and ship radar data. The ice drift is estimated for automatically selected ice targets in the images. These targets are here called virtual buoys (VBs) and are tracked based on an optical flow method. To maintain continuous ice drift tracking new VBs are added after a given number of VBs have been lost; i.e. they can not be tracked reliably any more. Here we also apply the algorithm to data of three test cases to demonstrate its capabilities and properties. Two of these cases use coastal radar data and one ship radar data. Ice drift velocity and direction information derived from the VB motion are computed and compared to the prevailing ice and weather conditions. Also a quantity measuring the local divergence or convergence is computed for some VBs to demonstrate the capability to estimate derived kinematic sea ice parameters from VB location time series. The results produced by the algorithm can be used as an input for estimation of the dynamic properties of sea the ice field, such as ice divergence or convergence, shear, vorticity, and total deformation.
Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984–2013
Authors: Chernos M. , Koppes M. , Moore R. D. 
Published: January 2016

Abstract. Bridge Glacier is a lake-calving glacier in the Coast Mountains of British Columbia and has retreated over 3.55 km since 1972. The majority of this retreat has occurred since 1991. This retreat is substantially greater than what has been inferred from regional climate indices, suggesting that it has been driven primarily by calving as the glacier retreated across an overdeepened basin. In order to better understand the primary drivers of ablation, surface melt (below the equilibrium line altitude, ELA) and calving were quantified during the 2013 melt season using a distributed energy balance model (DEBM) and time-lapse imagery. Calving, estimated using areal change, velocity measurements, and assuming flotation were responsible for 23 % of the glacier's ablation below the ELA during the 2013 melt season and were limited by modest flow speeds and a small terminus cross-section. Calving and surface melt estimates from 1984 to 2013 suggest that calving was consistently a smaller contributor of ablation. Although calving was estimated to be responsible for up to 49 % of the glacier's ablation for individual seasons, averaged over multiple summers it accounted between 10 and 25 %. Calving was enhanced primarily by buoyancy and water depths, and fluxes were greatest between 2005 and 2010 as the glacier retreated over the deepest part of Bridge Lake. The recent rapid rate of calving is part of a transient stage in the glacier's retreat and is expected to diminish within 10 years as the terminus recedes into shallower water at the proximal end of the lake. These findings are in line with observations from other lake-calving glacier studies across the globe and suggest a common large-scale pattern in calving-induced retreat in lake-terminating alpine glaciers. Despite enhancing glacial retreat, calving remains a relatively small component of ablation and is expected to decrease in importance in the future. Hence, surface melt remains the primary driver of ablation at Bridge Glacier and thus projections of future retreat should be more closely tied to climate.
Examining moisture pathways and extreme precipitation in the U.S. Intermountain West using self‐organizing maps
Authors: Swales Dustin , Alexander Mike , Hughes Mimi 
Published: January 2016

AbstractSelf‐organizing maps (SOMs) were used to explore relationships between large‐scale synoptic conditions, especially vertically integrated water vapor transport (IVT), and extreme precipitation events in the U.S. Intermountain West (IMW). By examining spatial patterns in the IVT, pathways are identified where moisture can penetrate into the IMW. A substantial number of extreme precipitation events in the IMW are associated with infrequently occurring synoptic patterns. The transition frequency between each of the SOM nodes, which indicate temporal relationships between the patterns, identified two synoptic settings associated with extreme precipitation in the IMW: (1) a landfalling, zonally propagating trough that results in a concentrated IVT band that moves southward as the system moves inland and (2) a southwesterly storm track associated with strong ridging over the coast that results in persistent IVT transport into the Pacific Northwest that can last for several days.
Large‐displacement, hydrothermal frictional properties of DFDP‐1 fault rocks, Alpine Fault, New Zealand: Implications for deep rupture propagation
Authors: Niemeijer A. R. , Boulton C. , Toy V. G. , Townend J. , Sutherland R. 
Published: January 2016

AbstractThe Alpine Fault, New Zealand, is a major plate‐bounding fault that accommodates 65–75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP‐1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity‐strengthening behavior to velocity‐weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity‐weakening region restricted to higher velocity for higher temperatures. Friction was substantially lower for low‐velocity shearing (V < 0.3 µm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate‐and‐state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity‐strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle‐plastic transition for quartzofeldspathic compositions.
Discriminating induced seismicity from natural earthquakes using moment tensors and source spectra
Authors: Zhang Hongliang , Eaton David W. , Li Ge , Liu Yajing , Harrington Rebecca M. 
Published: January 2016

AbstractEarthquake source mechanisms and spectra can provide important clues to aid in discriminating between natural and induced events. In this study, we calculate moment tensors and stress drop values for eight recent induced earthquakes in the Western Canadian Sedimentary Basin with magnitudes between 3.2 and 4.4, as well as a nearby magnitude 5.3 event that is interpreted as a natural earthquake. We calculate full moment tensor solutions by performing a waveform‐fitting procedure based on a 1‐D transversely isotropic velocity model. In addition to a dominant double‐couple (DC) signature that is common to nearly all events, most induced events exhibit significant non‐double‐couple components. A parameter sensitivity analysis indicates that spurious non‐DC components are negligible if the signal to noise ratio (SNR) exceeds 10 and if the 1‐D model differs from the true velocity structure by less than 5%. Estimated focal depths of induced events are significantly shallower than the typical range of focal depths for intraplate earthquakes in the Canadian Shield. Stress drops of the eight induced events were estimated using a generalized spectral‐fitting method and fall within the typical range of 2 to 90 MPa for tectonic earthquakes. Elastic moduli changes due to the brittle damage production at the source, presence of multiple intersecting fractures, dilatant jogs created at the overlapping areas of multiple fractures, or non‐planar pre‐existing faults may explain the non‐DC components for induced events.
Methods of calculation of the Atlantic meridional heat and volume transports from ocean models at 26.5°N
Authors: Stepanov Vladimir N. , Iovino Doroteaciro , Masina Simona , Storto Andrea , Cipollone Andrea 
Published: January 2016

AbstractThe Atlantic meridional overturning circulation (AMOC) and the associated meridional heat transport (MHT) at 26.5°N are investigated in two global ocean models at different resolutions and setup and compared with observational estimates from the Rapid Climate Change programme (RAPID). Three different methods of calculation are used to compute the modelled meridional transports: the first method (MOCmod) is based on simulated velocity fields, the second (MOC_endpoint) relies on the same assumptions as for the RAPID calculations, and the third (MOC_ff_baro) is also based on hydrostatic and geostrophic relationships, but relative to the model barotropic circulation. All methods correctly reproduce the time‐mean AMOC strength at 26.5°N, although some differences with observations are present at depth. Similar to other model results, despite the higher AMOC simulated by our eddy‐rich global model, the corresponding heat transport is significantly lower than the RAPID estimates. The above described differences between the deep structure of the modelled and observed AMOC impact the heat transport less than the discrepancies between the MOCmod and MOC_endpoint AMOC structure in the upper ∼500 m layer. The comparison of the AMOC obtained by the three methods suggests that an inadequate representation of currents near the western boundary by geostrophy leads to underestimate the southward circulation in the upper‐mid ocean and largely impact the heat transport calculations. In our analysis, calculation based on RAPID assumptions (applied in MOC_endpoint) result in a higher mean heat transport (>25%) compared to MOCmod calculation.
Observed and modeled tropospheric cold anomalies associated with sudden stratospheric warmings
Authors: Lehtonen Ilari , Karpechko Alexey Yu. 
Published: January 2016

AbstractSurface weather patterns related to 35 major sudden stratospheric warmings (SSWs) in 1958–2010 are analyzed based on reanalysis data. Similar analyses are conducted with data from seven stratosphere‐resolving Earth system models. The analyses are carried out separately for displacement and splitting SSWs. On the basis of the observational analysis, it is shown that in northern Eurasia, the cold anomalies linked to the SSWs tend to be stronger and more widespread before the central date of the SSWs than during the first 2 months after the event central dates. This is particularly true for the displacement events. The cold anomalies preceding the SSWs are coupled to atmospheric blocking events which trigger the SSWs. While the role of SSWs as important predictors of cold air outbreaks in the Northern Hemisphere is well recognized, our results indicate that the impact of the preceding blocking on near‐surface temperatures is, in fact, widely more significant than the downward impact of the SSWs. Thus, stratosphere‐troposphere coupling provides only limited predictability for cold air outbreaks in Eurasia. The models reproduce qualitatively well the typical large‐scale surface weather patterns following the SSWs, but they largely miss the cooling preceding the SSWs over Europe and western Siberia. Hence, the strongest modeled temperature anomalies related to the SSWs occur after the events. Moreover, the model results indicate that the tropospheric response to SSWs is stronger following split events. At the same time, many models simulate too few splitting SSWs.
Automatic detection of alpine rockslides in continuous seismic data using hidden Markov models
Authors: Dammeier Franziska , Moore Jeffrey R. , Hammer Conny , Haslinger Florian , Loew Simon 
Published: January 2016

AbstractData from continuously recording permanent seismic networks can contain information about rockslide occurrence and timing complementary to eyewitness observations and thus aid in construction of robust event catalogs. However, detecting infrequent rockslide signals within large volumes of continuous seismic waveform data remains challenging and often requires demanding manual intervention. We adapted an automatic classification method using hidden Markov models to detect rockslide signals in seismic data from two stations in central Switzerland. We first processed 21 known rockslides, with event volumes spanning 3 orders of magnitude and station event distances varying by 1 order of magnitude, which resulted in 13 and 19 successfully classified events at the two stations. Retraining the models to incorporate seismic noise from the day of the event improved the respective results to 16 and 19 successful classifications. The missed events generally had low signal‐to‐noise ratio and small to medium volumes. We then processed nearly 14 years of continuous seismic data from the same two stations to detect previously unknown events. After postprocessing, we classified 30 new events as rockslides, of which we could verify three through independent observation. In particular, the largest new event, with estimated volume of 500,000 m3, was not generally known within the Swiss landslide community, highlighting the importance of regional seismic data analysis even in densely populated mountainous regions. Our method can be easily implemented as part of existing earthquake monitoring systems, and with an average event detection rate of about two per month, manual verification would not significantly increase operational workload.
Younger Dryas sea level and meltwater pulse 1B recorded in Barbados reef crest coral Acropora palmata
Authors: Abdul N. A. , Mortlock R. A. , Wright J. D. , Fairbanks R. G. 
Published: January 2016

AbstractThe Younger Dryas climate event occurred during the middle of the last deglacial cycle and is marked by an abrupt shift in the North Atlantic polar front almost to its former glacial position, trending east to west. Using high‐precision and high‐accuracy U‐Th‐dated Barbados reef crest coral, Acropora palmata, we generate a detailed sea level record from 13.9 to 9000 years before present (kyr B.P.) and reconstruct the ice volume response to the Younger Dryas cooling. From the mid‐Allerød (13.9 kyr B.P.) to the end of the Younger Dryas (11.65 kyr B.P.), rates of sea level rise decreased smoothly from 20 mm yr−1 to 4 mm yr−1, culminating in a 400 year “slow stand” before accelerating into meltwater pulse 1B (MWP‐1B). The MWP‐1B event at Barbados is better constrained as beginning by 11.45 kyr B.P. and ending at 11.1 kyr B.P. during which time sea level rose 14 ± 2 m and rates of sea level rise reached 40 mm yr−1. We propose that MWP‐1B is the direct albeit lagged response of the Northern Hemisphere ice sheets to the rapid warming marking the end of the Younger Dryas coinciding with rapid warming in the circum‐North Atlantic region and the polar front shift from its zonal to meridional position 11.65 kyr B.P. As predicted by glaciological models, the ice sheet response to rapid North Atlantic warming was lagged by 400 years due to the thermal inertia of large ice sheets. The regional circum‐North Atlantic Younger Dryas climate event is elevated to a global response through sea level changes, starting with the global slowdown in sea level rise during the Younger Dryas and culminating with MWP‐1B. No meltwater pulses are evident at the initiation of the Younger Dryas climate event as is often speculated.