bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Eddy Covariance to Measure the Dependence of Air-Sea CO2 Exchange Rate on Friction Velocity
Authors: Landwehr Sebastian , Miller Scott D. , Smith Murray J. , Bell Thomas G. , Saltzman Eric S. , Ward Brian
Published: November 2017

Abstract. Parameterisation of the air-sea gas transfer velocity of CO2 and other trace gases under open-ocean conditions has been a focus of air-sea interaction research and is required for accurately determining ocean carbon uptake. Ships are the most widely used platform for air-sea flux measurements but the quality of the data can be compromised by air flow distortion and sensor cross-sensitivity effects. Recent improvements in the understanding of these effects have led to enhanced corrections to the shipboard eddy covariance (EC) measurements. Here we present a revised analysis of eddy covariance measurements of air-sea CO2 and momentum fluxes from the Southern Ocean Surface Ocean Aerosol Production study (SOAP). We show that it is possible to significantly reduce the scatter in the EC data and achieve consistency between measurements taken on-station and with the ship underway. The gas transfer velocities from the EC measurements correlate better with the EC friction velocity (u*) than with mean wind speeds derived from shipboard measurements corrected with an air flow distortion model. For the observed range of wind speeds (u10N = 3–23 m s−1), the transfer velocities can be parameterised with a linear fit to u*. The SOAP data are compared to previous gas transfer parameterisations using u10N computed from the EC friction velocity with the drag coefficient from the COARE model. The SOAP results are consistent with previous gas transfer studies, but at high wind speeds they do not support the sharp increase in gas transfer associated with bubble-mediated transfer predicted by physically based models.
Aerosol-type retrieval and uncertainty quantification from OMI data
Authors: Kauppi Anu , Kolmonen Pekka , Laine Marko , Tamminen Johanna
Published: November 2017

Abstract. We discuss uncertainty quantification for aerosol-type selection in satellite-based atmospheric aerosol retrieval. The retrieval procedure uses precalculated aerosol microphysical models stored in look-up tables (LUTs) and top-of-atmosphere (TOA) spectral reflectance measurements to solve the aerosol characteristics. The forward model approximations cause systematic differences between the modelled and observed reflectance. Acknowledging this model discrepancy as a source of uncertainty allows us to produce more realistic uncertainty estimates and assists the selection of the most appropriate LUTs for each individual retrieval.This paper focuses on the aerosol microphysical model selection and characterisation of uncertainty in the retrieved aerosol type and aerosol optical depth (AOD). The concept of model evidence is used as a tool for model comparison. The method is based on Bayesian inference approach, in which all uncertainties are described as a posterior probability distribution. When there is no single best-matching aerosol microphysical model, we use a statistical technique based on Bayesian model averaging to combine AOD posterior probability densities of the best-fitting models to obtain an averaged AOD estimate. We also determine the shared evidence of the best-matching models of a certain main aerosol type in order to quantify how plausible it is that it represents the underlying atmospheric aerosol conditions.The developed method is applied to Ozone Monitoring Instrument (OMI) measurements using a multiwavelength approach for retrieving the aerosol type and AOD estimate with uncertainty quantification for cloud-free over-land pixels. Several larger pixel set areas were studied in order to investigate the robustness of the developed method. We evaluated the retrieved AOD by comparison with ground-based measurements at example sites. We found that the uncertainty of AOD expressed by posterior probability distribution reflects the difficulty in model selection. The posterior probability distribution can provide a comprehensive characterisation of the uncertainty in this kind of problem for aerosol-type selection. As a result, the proposed method can account for the model error and also include the model selection uncertainty in the total uncertainty budget.
Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia
Authors: Ayehu Getachew Tesfaye , Tadesse Tsegaye , Gessesse Berhan , Dinku Tufa
Published: November 2017

Abstract. Accurate measurement of rainfall is vital to analyze the spatial and temporal patterns of precipitation at various scales. However, the conventional rain gauge observations in many parts of the world such as Ethiopia are sparse and unevenly distributed. An alternative to traditional rain gauge observations could be satellite-based rainfall estimates. Satellite rainfall estimates could be used as a sole product (e.g. in areas with no (poor) ground observations) or through integrating with rain gauge measurements. In this study, the newly available Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data has been evaluated in comparison to rain gauge data for the period of 2000 to 2015 across the Upper Blue Nile basin in Ethiopia. Besides, the Tropical Applications of Meteorology using SATellite and ground-based observations (TAMSAT) version 2 and 3 (TAMSAT 2 and TAMSAT 3) and the African Rainfall Climatology (ARC 2) products have been used as a benchmark and compared with CHIRPS. The TAMSAT 2 rainfall estimate was used in this study mainly to assess the improvements made with the recent version of a TAMSAT product (TAMSAT 3). From the overall analysis at dekadal and monthly temporal scale, CHIRPS exhibited higher skills and the best bias value in comparison to ARC 2 but overestimates the frequency of rainfall occurrence particularly during the dry months. On the other hand, TAMSAT 3 has shown very comparable performance with that of CHIRPS product, particularly with regards to bias. The ARC 2 product was found to have the weakest performance underestimating rainfall amounts by about 24 %. The skill of CHIRPS is less affected by variation in elevation in comparison to TAMSAT 3 and ARC 2 products. While ARC 2 was found to be affected by elevation with the average biases of 1.53, 0.86 and 0.77 at lower ( 2000 m a.s.l), respectively. Comparing the overall performance of the three products, CHIRPS exhibited the best performance followed closely by TAMSAT 3. This validation study also shows that the TAMSAT 3 has overcome the main weaknesses of TAMSAT 2, which is underestimation of high rainfall amounts by up to 31 % in this study. Overall, the finding of this validation study shows the potentials of CHIRPS product to be used for various operational applications such as rainfall pattern and variability study in the Upper Blue Nile basin in Ethiopia.
On the improved stability of the version 7 MIPAS ozone record
Authors: Laeng Alexandra , Eckert Ellen , von Clarmann Thomas , Kiefer Michael , Hubert Daan , Stiller Gabriele , Grabowski Udo , Glatthor Norbert , Plieninger Johannes , Kellmann Sylvia , Linden Andrea , Lossow Stefan , Babenhauserheide Arne , Froidevaux Lucien , Walker Kaley
Published: November 2017

Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was an IR limb emission spectrometer on the Envisat platform. From 2002 to 2012, it performed pole-to-pole measurements during day and night, producing more than 1000 profiles/day. The European Space Agency (ESA) has recently released the new version 7 of Level 1 MIPAS spectra, in which a new set of time-dependent correction coefficients for the non-linearity in the detectors’ response functions was implemeted. This change is expected to reduce the long-term drift of the MIPAS Level 2 data. We evaluate the long-term stability of ozone level 2 data retrieved from MIPAS V7 Level 1 spectra with the IMK/IAA Scientific Level 2 Processor. We compare it with ozone measurements from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite, ozonesondes and ground-based lidar instruments. The ozonesondes and lidars alone do not allow us to conclude with enough significance that the new version is more stable than the previous one, but a clear improvement in long-term stability is observed in the satellite-data based drift analysis. The results of ozonesondes, lidars and satellite drift analysis are consistent: all indicate that the drifts of the new version are less negative/more positive nearly everywhere above 15 km. These results indicate that MIPAS data are now even more suited for trend studies, alone or as part of a merged data record.
Bayesian Dark Target Algorithm for MODIS AOD retrieval over land
Authors: Lipponen Antti , Mielonen Tero , Pitkänen Mikko R. A. , Levy Robert C. , Sawyer Virginia R. , Romakkaniemi Sami , Kolehmainen Ville , Arola Antti
Published: November 2017

Abstract. We have developed a Bayesian Dark Target (BDT) algorithm for the Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) retrieval over land. In the BDT algorithm, we simultaneously retrieve all pixels in a granule, utilize spatial correlation models for the unknown aerosol parameters, use a statistical prior model for the surface reflectance, and take into account the uncertainties due to fixed aerosol models. The retrieved parameters are total AOD at 550 nm, fine-mode fraction (FMF), and surface reflectances at four different wavelengths (466, 550, 644, and 2100 nm). The accuracy of the new algorithm is evaluated by comparing the AOD retrievals to Aerosol Robotic Network (AERONET) AOD. The results show that the BDT significantly improves the accuracy of AOD retrievals over the operational Dark Target (DT) algorithm. A reduction of about 29 % in the AOD root mean square error and decrease of about 80 % in the median bias of AOD were found globally when the BDT was used instead of the DT algorithm. Furthermore, the fraction of AOD retrievals inside the ±(0.05 + 15 %) expected error envelope increased from 55 % to 76 %. In addition to retrieving the values of AOD, FMF and surface reflectance, the BDT also gives pixel-level posterior uncertainty estimates for the retrieved parameters. The BDT algorithm always results in physical, non-negative AOD values, and the average computation time for a single granule was less than a minute on a modern personal computer.
The mutually antagonistic effect of drought and sand burial enables the biocrust moss Bryum argenteum Hedw. to survive the two co-occurring stressors in an arid sandy desert
Authors: Jia Rongliang , Zhao Yun , Gao Yanhong , Hui Rong , Yang Haotian , Wang Zenru
Published: November 2017

Abstract. Biocrust moss is an essential soil surface bio-cover. It represents the highest succession stage among the diverse range of surface-dwelling cryptogams (e.g., cyanobacteria, green algae, and lichen, which are also referred to as biological soil crusts) and makes a major contribution to soil stability and fertility throughout arid desert ecosystems. The soil surface represents a small ecological niche that is poikilohydric in nature. Biocrust moss is therefore highly susceptible to drought and sand burial, which are two ubiquitous stressors in arid sandy deserts. However, little information is available regarding the mechanism by which biocrust moss can survive and flourish in these habitats when stressed simultaneously by the two stressors. The combined effects of drought and sand burial were evaluated in a field experiment using the predominant biocrust moss, Bryum argenteum Hedw., in the Tengger Desert, China. Drought was simulated by applying distilled water in three artificial rainfall regimes at 8-day intervals in spring and autumn: 4 and 6 mm (average rainfall, control), 2 and 3 mm (double drought), and 1 and 1.5 mm (fourfold drought), respectively. The effect of sand burial was determined by applying six treatments, i.e., sand depths of 0 (control), 0.5, 1, 2, 4, and 10 mm. The four parameters of chlorophyll a content, PSII photochemical efficiency, regeneration potential, and shoot upgrowth were evaluated in the moss. It was found that the combined effects of drought and sand burial did not exacerbate the single negative effects of the four parameters tested. Drought significantly ameliorated the negative effects of deep sand burial on the retention of chlorophyll a content, PSII photochemical efficiency, and regeneration potential of B. argenteum. Sand burial diminished and even reversed the negative effects of drought on the maintenance of chlorophyll a content, PSII photochemical efficiency, and regeneration potential. Although drought and sand burial imposed an additive negative effect on shoot upgrowth, which suggested a trade-off between growth ability and stress tolerance, their mutually antagonistic effect on the physiological vigor of B. argenteum provided an opportunity for the biocrust moss to overcome the two co-occurring stressors. In addition to providing a strong stress tolerance, drought and sand burial may provide an important mechanism for the biodiversity maintenance of biocrust mosses in arid sandy ecosystems.
Small spatial but large sporadic variability in methane emission measured from a
patterned boreal bog
Authors: Korrensalo Aino , Männistö Elisa , Alekseychik Pavel , Mammarella Ivan , Rinne Janne , Vesala Timo , Tuittila Eeva-Stiina
Published: November 2017

Abstract. We measured methane fluxes of a patterned bog from six different plant community types in three growing seasons 2012–2014 using the static chamber method. A mixed effects model was applied for quantifying the effect of the controlling factors on the methane flux. The plant community types differed from each other in their water level, total leaf area (LAITOT) and leaf area of aerenchymatous plant species (LAIAER). Excluding the highest 2.5 % of all fluxes, methane emissions ranged from −309 to 556 mg m−2 d−1. Although methane fluxes increased with increasing peat temperature, LAITOT and LAIAER, they had no correlation with water table or with plant community type. The only exception were higher fluxes from hummocks than from other plant community types in 2013. Chamber fluxes upscaled to ecosystem level for the peak season were of the same magnitude as the fluxes measured with the eddy covariance (EC) technique. In 2012 and in August 2014 there was a good agreement between the two methods, in 2013 and in July 2014, the chamber fluxes were higher than the EC fluxes. Net fluxes to soil, indicating higher methane oxidation than production, were detected every year and on all community types. Exceptionally high methane emissions up to 17 000 mg m−2 d−1 were measured sporadically in 2013 and 2014. These extreme emissions not detected in EC measurements we were not able to exclude as measurement errors and they did not correlate with any measured variables. Our results underline the importance of both LAIAER and LAITOT in controlling methane fluxes and indicate need for automatized chambers to reliably capture localized events to support more robust EC method.
Palaeoclimate evolution across the Cretaceous–Palaeogene boundary in the Nanxiong Basin (SE China) recorded by red strata and its correlation with marine records
Authors: Ma Mingming , Liu Xiuming , Wang Wenyan
Published: November 2017

Abstract. The climate during the Cretaceous Period represented one of the greenhouse states of Earth's history. Significant transformation of climate patterns and a mass extinction event characterised by the disappearance of dinosaurs occurred across Cretaceous–Palaeogene boundary. However, most records of this interval are derived from marine sediments. The continuous and well-exposed red strata of the Nanxiong Basin (SE China) provide ideal material to develop continental records. Considerable research into stratigraphic, palaeontological, chronologic, palaeoclimatic, and tectonic aspects has been carried out for the Datang Profile, which is a type section of a non-marine Cretaceous–Palaeogene stratigraphic division in China. For this study, we reviewed previous work and found that: 1) the existing chronological framework of the Datang Profile is flawed; 2) precise palaeoclimatic reconstruction is lacking because of the limitations of sampling resolution (e.g. carbonate samples) and/or the lack of efficient proxies; and 3) comparisons of climate changes between marine and continental records are lacking. To resolve these problems, detailed field observations and sampling, as well as environmental magnetic and rare earth element (REE) measurements, were carried out. The results show that: 1) more accurate ages of the Datang Profile range from 72 Ma to 62.8 Ma, based on a combination of the most recently published radiometric, palaeontological and palaeomagnetic ages; 2) there is considerable evidence of palaeosol generation, which indicates that the red strata formed in a long-term hot, oxidizing environment that lacked of underwater condition; 3) haematite was the dominant magnetic mineral in the red strata, and the variation trend of magnetic susceptibility was consistent with the oxygen isotope records from deep-sea sediments, which indicates that the pedogenic intensity was controlled by global climate; and 4) the palaeoclimate changes from 72 Ma to 62.8 Ma in the Nanxiong Basin were consistent with global patterns, and can be divided into three stages: a relatively hot and wet stage during 72–71.5 Ma, a cool and arid stage during 71.5–66 Ma, and a relatively hot and wet stage again during 66–62.8 Ma with a notable drying and cooling event at 64.7–63.4 Ma. Moreover, there are several sub-fluctuations during each stage. This work provides basic information for further palaeoclimate reconstruction with higher resolution and longer time scales for the Cretaceous to Palaeocene in the Nanxiong Basin, and may even help to test ocean–land climate interactions in the future.
Hazards of decreasing marine oxygen: the near-term and
millennial-scale benefits of meeting the Paris climate targets
Authors: Battaglia Gianna , Joos Fortunat
Published: November 2017

Abstract. Ocean deoxygenation is recognized as key ecosystem stressor of the future ocean and associated climate-related ocean risks are relevant for policy decisions today. In particular, benefits of reaching the ambitious 1.5 °C warming target mentioned by the Paris Agreement compared to higher temperature targets are of high interest. Here, we model oceanic oxygen, warming, and their compound hazard in terms of metabolic conditions on multi-millennial timescales for a range of temperature targets. Scenarios, where radiative forcing is stabilized by 2300, are used in ensemble simulations with the Bern3D Earth System Model of Intermediate Complexity. Transiently, the global mean ocean oxygen concentration decreases by a few percent under low and by 40 % under high forcing. Deoxygenation peaks about thousand years after stabilization of radiative forcing. Hypoxic waters expand over the next millennium and recovery is slow and remains incomplete under high forcing. Largest transient decreases in oxygen are projected for the deep sea. Distinct and close to linear relationships between the equilibrium temperature response and marine O2 loss emerge. These point to the effectiveness of the Paris climate target in reducing marine hazards and risks. Mitigation measures are projected to reduce peak decreases in oceanic oxygen inventory by 4.4 % °C−1 of avoided equilibrium warming. In the upper ocean, the decline of a metabolic index, quantified by the ratio of O2 supply to an organism's O2 demand, is reduced by 6.2 % °C−1 of avoided equilibrium warming. Measures of peak hypoxia exhibit a strong sensitivity to additional warming. Volumes of water with less than 50 mmol O2 m−3, for instance, increase between 36 % to 76 % °C−1 of equilibrium temperature response. Our results show that millennial-scale responses should be considered in assessments of ocean deoxygenation and associated climate-related ocean risks. Peak hazards occur long after stabilization of radiative forcing and new steady state conditions establish after AD 8000.
Assessing Carbon Dioxide Removal Through Global and Regional Ocean Alkalization under High and Low Emission Pathways
Authors: Lenton Andrew , Matear Richard J. , Keller David P. , Scott Vivian , Vaughan Naomi E.
Published: November 2017

Abstract. Atmospheric CO2 levels continue to rise, increasing the risk of severe impacts on the Earth system, and on the ecosystem services that it provides. Artificial Ocean Alkalization (AOA) is capable of reducing atmospheric CO2 concentrations, surface warming and addressing ocean acidification. Here we simulate global and regional responses to alkalinity addition (0.25 PmolAlk/year) using the CSIRO-Mk3L-COAL Earth System Model in the period 2020–2100, under high (RCP8.5) and low (RCP2.6) emissions. While regionally there are large changes associated with locations of AOA, globally we see only a very weak dependence on where and when AOA is applied. We see that under RCP2.6, while the carbon uptake associated with AOA is only ~ 60 % of the total under RCP8.5, the relative changes in temperature are larger, as are the changes in pH (1.4×) and aragonite saturation (1.7×). The results of this modelling study are significant as they demonstrate that AOA is more effective under lower emissions, and the higher the emissions the more AOA required to achieve the same reduction in global warming and ocean acidification. Finally, our simulations show AOA in the period 2020–2100 is capable of offsetting global warming and ameliorating ocean acidification increases due to low emissions, but regionally the response is more variable.
The Palaeoclimate and Terrestrial Exoplanet Radiative Transfer Model Intercomparison Project (PALAEOTRIP): experimental design and protocols
Authors: Goldblatt Colin , Kavanagh Lucas , Dewey Maura
Published: November 2017

Abstract. Accurate radiative transfer calculation is fundamental to all climate modelling. For deep palaeoclimate, and increasingly terrestrial exoplanet climate science, this brings both the joy and the challenge of exotic atmospheric compositions. The challenge here is that most standard radiation codes for climate modelling have been developed for modern atmospheric conditions and may perform poorly away from these. The palaeoclimate or exoclimate modeller must either rely on these or use bespoke radiation codes, and in both cases rely on either blind faith or ad hoc testing of the code. In this paper, we describe the protocols for the Palaeoclimate and Terrestrial Exoplanet Radiative Transfer Model Intercomparison Project (PALAEOTRIP) to systematically address this. This will compare as many radiation codes used for palaeoclimate or exoplanets as possible, with the aim of identifying the ranges of far-from-modern atmospheric compositions in which the codes perform well. This paper describes the experimental protocol and invites community participation in the project through 2017–2018.
Hydrological control of dissolved organic carbon dynamics in a
rehabilitated Sphagnum–dominated peatland: a water-table based
modelling approach
Authors: Bernard-Jannin Léonard , Binet Stéphane , Gogo Sébastien , Leroy Fabien , Défarge Christian , Jozja Nevila , Zocatelli Renata , Perdereau Laurent , Laggoun-Défarge Fatima
Published: November 2017

Abstract. Hydrological disturbances could increase dissolved organic carbon (DOC) exports through runoff and leaching, reducing the potential carbon sink function of peatlands. The objective of this study was to assess the impact of hydrological restoration on hydrological processes and DOC dynamics in a rehabilitated Sphagnum–dominated peatland. A conceptual hydrological model calibrated on the water table and coupled with a biogeochemical module was applied to La Guette peatland (France), which experienced a rewetting action on February 2014. The model (ten calibrated parameters) reproduced water table and pore water DOC concentration time series (01/04/2014 to 15/07/2017) in two contrasted locations (rewetted and control) of the peatland. Hydrological restoration was found to impact the water balance through a decrease in slow deep drainage and an increase in fast superficial runoff. Observed DOC concentrations were higher in summer in the rewetted location compared to the control and were linked with a difference in dissolved organic matter composition analyzed by fluorescence. Hydrological conditions, especially the severity of the water table drawdown, were identified as the major factors controlling DOC concentration dynamics. The results of the simulation suggest that the hydrological restoration did not affect DOC loads, at least on a short-term period (3 years). However, it impacted the temporal dynamics of DOC exports, which were the most episodic and mainly transported through fast surface runoff in the area affected by the restoration while slow deep drainage dominated DOC exports in the control area. In relation with dominant hydrological processes, exported DOC is expected to be derived from more recent organic matter of the top peat layer in the rewetted area than in the control area. Since it is calibrated on water table and DOC concentration, the model presented in this study proved to be a relevant tool to identify the main hydrological processes and factors controlling DOC dynamics in different areas of the same peatland. It is also a suitable alternative to a discharge calibrated catchment model when the outlet is not easily identifiable.
Harnessing Big Data to Rethink Land Heterogeneity in Earth
System Models
Authors: Chaney Nathaniel W. , Van Huijgevoort Marjolein H. J. , Shevliakova Elena , Malyshev Sergey , Milly Paul C. D. , Gauthier Paul P. G. , Sulman Benjamin N.
Published: November 2017

Abstract. The continual growth in the availability, detail, and wealth of environmental data provides an invaluable asset to improve the characterization of land heterogeneity in Earth System models – a persistent challenge in macroscale models. However, due to the nature of these data (volume and complexity) and the computational constraints of macroscale models, until now these data have been underutilized for global applications. As a proof of concept, this study explores over a 1/4 degree (~ 25 km) grid cell in southeastern California how to effectively and efficiently harness these data in Earth System models. First, a novel hierarchical multivariate clustering approach (HMC) is used to summarize the high dimensional environmental data space into hydrologically interconnected representative clusters (i.e., tiles). These tiles and their associated properties are then used to parameterize the sub-grid heterogeneity of the Geophysical Fluid Dynamics Laboratory (GFDL) LM4-HB land model. To assess how this data-driven approach to assemble the model tiles impacts the simulated water, energy, and carbon cycles, model experiments are run using a series of different tile configurations assembled by HMC. The results over the 1/4 degree macroscale grid cell and the underlying 30-meter fine-scale grid in southeastern California show that: 1) the observed similarity over the landscape makes it possible to robustly account for the role of multi-scale heterogeneity in the macroscale states and fluxes with around 300 sub-grid land model tiles; 2) assembling the sub-grid tiles from observed data, at times, leads to noticeable differences in the macroscale water, energy, and carbon cycles; for example, explicit subsurface interactions between the tiles leads to a dampening of macroscale extremes; 3) connecting the fine-scale grid to the model tiles via HMC enables circumventing the classic scale discrepancies between the macroscale and field-scale estimates; this has potentially significant implications for the evaluation and application of Earth System models.
Assessing the long-term hydrologic response to wildfires in
mountainous regions
Authors: Havel Aaron , Tasdighi Ali , Arabi Mazdak
Published: November 2017

Abstract. This study aims to understand the long-term hydrologic responses to wildfires in mountainous regions at various spatial scales. The Soil and Water Assessment Tool (SWAT) was used to evaluate hydrologic response of the upper Cache la Poudre watershed in Colorado to the 2012 High Park and Hewlett wildfire events. A baseline SWAT model was established to simulate the hydrology of the study area between the years 2000 and 2014. The effects of wildfires on land cover were accounted for in the model using the SWAT land use update module. The wildfire effects on curve numbers were determined comparing the probability distribution of curve numbers after calibrating the model for pre and post wildfire conditions. Daily calibration and testing of the model produced very good results. No-wildfire and wildfire scenarios were created and compared to quantify changes in average annual total runoff volume, water budgets, and full streamflow statistics at different spatial scales. At the watershed scale, wildfire conditions showed little impact on the hydrologic responses. However, a runoff increase up to 75 percent was observed between the scenarios in sub-watersheds with high burn intensity. Generally, higher surface runoff and decreased subsurface flow were observed under post-wildfire conditions. Flow-duration curves developed for burned sub-basins using full streamflow statistics showed that less frequent streamflows become greater in magnitude. A strong (R2 > 0.8) and significant (p
The temporally varying roles of rainfall, snowmelt and soil moisture
for debris flow initiation in a snow dominated system: the compound
trigger concept
Authors: Mostbauer Karin , Kaitna Roland , Prenner David , Hrachowitz Markus
Published: November 2017

Abstract. Debris flows represent a severe hazard in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system and to overcome the above limitations, this study explores the use of a semi-distributed conceptual rainfall-runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, western Austria. The model was run on a daily basis between 1953 and 2012. Analyzing a range of modelled system state and flux variables at days on which debris flows occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68 % (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as dominant trigger for 24 % (6 out of 25) of the observed debris flow events. In addition, 8 % (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as trigger being limited to mid- and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and more specifically, their temporally varying importance relative to each other, rather than their absolute values, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms in a compound trigger concept, highlighting in particular the relevance of snowmelt contributions and the switch between mechanisms in early- to mid-summer in snow dominated systems.
Assessing fragility of a reinforced concrete element to snow
avalanches using a non-linear mass-spring model
Authors: Favier Philomène , Bertrand David , Eckert Nicolas , Ousset Isabelle , Naaim Mohamed
Published: November 2017

Abstract. This paper presents an assessment of the fragility of a Reinforced Concrete (RC) element subjected to avalanche loads within a reliability framework. In order to obtain accurate numerical results with supportable computation times, we propose a light and efficient Single-Degree-Of-Freedom (SDOF) numerical model for an RC element. The model represents the behavior of an RC wall, summing up the main physics involved. Non-linearity was taken into account by a moment-curvature approach, which describes the overall bending response until collapse. The SDOF model was validated by a finite element as well as yield line theory analyses. It was then embedded within a reliability framework to evaluate the failure probability as a function of avalanche pressure. Several reliability methods were implemented and compared, suggesting that non-parametric methods provide significant results at a moderate level of computational burden. The sensitivity to material properties, such as tensile and compressive strengths, steel reinforcement ratio, and wall geometry was also investigated. Finally, the obtained fragility curves were discussed with respect to the few proposals available in the snow avalanche engineering field. This systematic approach will prove useful in refining formal and practical risk assessments and could be applied to other phenomena that also lack fragility curves.
Risk-based analysis of monitoring time intervals for landslide
prevention
Authors: Lee Jongook , Lee Dong Kun , Kil Sung-Ho , Kim Ho Gul
Published: November 2017

Abstract. Landslide is one of the most dangerous disasters in terms of occurrence frequency and damage severity that result in loss of human life and social infrastructure. Monitoring methods based on low temporal resolution instruments such as an inclinometer or piezometer can be an effective and cost-efficient solution. The objective of this research is to analyse monitoring time intervals for low temporal resolution methods based on a risk study and to propose a plan for periodic landslide monitoring along with the different landslide hazard areas by considering the risk reduction effect. For this purpose, an equation for the probability of landslide occurrence was denoted by the concept of reliability, and the monitoring time interval was analysed quantitatively by calculating the average probability of landslide occurrence. To identity the frequency of landslide occurrence, a unit of relative temporal frequencies was adopted, and it was estimated by establishing rainfall threshold. As a case study site, Pyeongchang County was selected, where landslide inventory data are available and an increase in population and infrastructure has been observed since Pyeongchang became the host city of the 2018 winter Olympic games. The result demonstrates that the appropriate monitoring intervals can be determined by calculating the average probability of landslide occurrence, and resources can then be allocated efficiently for landslide prevention.
Experimental study of sediment traps permeable for frequent floods
Authors: Schwindt Sebastian , Franca Mário J. , Reffo Alessandro , Schleiss Anton J.
Published: November 2017

Abstract. Sediment traps created by partially open torrential barriers are crucial elements for flood protection in alpine regions. The trapping of sediment is necessary when intense sediment transport occurs during floods that may endanger urban areas at downstream river reaches. In turn, the unwanted permanent trapping of sediment during small, non-hazardous floods can result in the ecological and morphological depletion of downstream reaches. This study experimentally analyses a new concept for permeable sediment traps. For ensuring the sediment transfer up to small floods, a guiding channel implemented in the deposition area of the sediment trap was studied systematically. The bankfull discharge of the guiding channel corresponds to a dominant morphological discharge. At the downstream end of the guiding channel, a permeable barrier triggers sediment retention and deposition. The permeable barrier consists of a bar screen for mechanical deposition control, superposed to a flow constriction for the hydraulic control. The fail-safe clogging of the barrier and the sediment deposition upstream can be ensured for discharges that are higher than the bankfull discharge of the guiding channel.
Moored observations of mesoscale features in the Cape Basin: Characteristics and local impacts on water mass distributions
Authors: Kersalé Marion , Lamont Tarron , Speich Sabrina , Terre Thierry , Laxenaire Remi , Roberts Mike J. , van den Berg Marcel A. , Ansorge Isabelle J.
Published: November 2017

Abstract. The eastern side of the SAMBA array (South Atlantic Meridional overturning circulation Basin-wide Array) along the latitude 34.5° S is used to assess the nonlinear, mesoscale dynamics of the Cape Basin. This array presently consists of current meter moorings and CPIES (bottom mounted Inverted Echo Sounders with pressure sensor and current meter) deployed across the continental slope. These data, available from September 2014 to December 2015, combined with satellite altimetry allow us to investigate the characteristics and the impact of these mesoscale structures on local water masses distribution and cross-validate the different data sets. We demonstrate that the upper slope moorings are affected by cyclonic eddies generated at the South Benguela upwelling front, while the deeper slope moorings are affected by the more complex dynamics of the Cape Basin involving Agulhas Rings and cyclonic eddies. This complex dynamics induces strong intra-seasonal upper-ocean velocity variations and water masses exchanges across the shelf and the open ocean, but also across the subantarctic and subtropical waters. Under four case studies, the full-water column hydrographic properties of each mesoscale feature has been evaluated. Our analyses show that exchange of water masses happens through the advection of water by mesoscale eddies but also via wide water mass intrusions engendered by the existence of intense dipoles. The high spatial and temporal scales resolved by the moorings allows us to define the substantial role of these mesoscale features over the full-water column. Future investigations with longer time series at these existing sites will lead to a better understanding of the eastern boundary current variability, and ultimately improve our understanding of the strength and variability of the Meridional Overturning Circulation.
Evaluation of adaptive facades: The case study of Al Bahr Towers in the UAE
Authors: Attia Shady
Published: November 2017

The assessment of adaptive facades presents a barrier as there is no established assessment technique. Many of the available facade performance evaluation systems or frameworks have limited applicability for such advanced building facades. The complexity of adaptive or dynamic facades' evaluation is related to the performance evaluation of facade elements, systems, and overall building performance coupled with occupant behavior and occupant satisfaction. In this context, this paper presents a case study of an adaptive sunscreen facade and evaluation of its performance and occupant behavior. The evaluation mainly focuses on pre- and post-construction phases of adaptive facades: the design assist phase (including the durability test, visual mockup, onsite mashrabiya mounting, and weather stripping), the commissioning phase (field verification and performance testing), and the monitoring phase. The selected project is a 150-meter-high twin tower that stands with a honeycomb-inspired structure and automated dynamic solar screen that responds to the sun's movement. These solar screens respond dynamically and automatically to the angle of the sun, which improves the control over energy consumption, solar radiation, and glare with the ability to allow natural light into the building. This paper is part of the research activities of working group 3 of the European COST Action 1403 on “Adaptive Facades”. Different methods were used for evaluation and these include the following: interviews with the architect, facade engineer, technical control specialist and occupants, reviews of standards and codes, review of energy models, and a systematic design process mapping. A documentation of the case study describing the post-construction occupant comfort and facade operation was prepared. This paper's audience comprises mainly project managers, architects, and building facade engineers together with facility managers who are concerned with the process of design, construction, and operation of adaptive sunscreens facades. The outcome of this study identifies quantifiable performance indicators and effective strategies for the design and performance evaluation of optimal adaptive facades.
The Effect of Suspended Salary Allowance on Business Loan in Saudi Arabia
Authors: Alessa Adlah A. , Alsaeed Wafa Fahad , Azibi Jamel , Ajina Aymen
Published: November 2017

The research was carried out to study two factors; first the impact of suspended Salary allowance (about 20% of Saudi Salary per month) on borrowing loans from national and commercial Saudi's banks. Secondly, to analyze the effects of suspended Salary allowance on re-payment of the loans. This study established that most Saudi banks’ customers should be well-aware of the influence of suspended Salary allowance on borrowing loans from banks and re-payment of the loans. It was noticed that the provision of loans to Saudi people after governmental action regarding suspended Salary allowance had a great impact on their businesses performance. The study also found that salary cuts together with other factors including high interest rates may be the most important causes of poor business performance.
The Agile Transition in Software Development Companies: The Most Common Barriers and How to Overcome Them
Authors: Obrutsky Santiago , Erturk Emre
Published: November 2017

The purpose of this paper is to investigate the most common barriers facing the greater adoption of Agile approaches to project management, and ways to overcome these barriers during an Agile transition. First, based on a literature review, this paper describes the Agile approaches and practices in general. The review also covers the previous work around the adoption of Agile, which provides considerable information about the challenges of doing so. This includes some prerequisites, key decisions, transitional frameworks, and recommendations to overcome organisational, cultural, and structural barriers. Next, this paper reports on a recently conducted Agile project management survey. Using this method, this research project gathered information about the important issues that software development companies have to overcome in order to be successful in an Agile transition. The survey was given to Scrum masters, project managers, chief executive officers, and IT professionals, who have participated in companies that have migrated from a traditional methodology to an Agile methodology. Several barriers were highlighted: general organisational resistance to change, lack of user/customer availability, pre-existing rigid framework, not enough personnel with Agile experience, concerns about loss of management control, concerns about lack of upfront planning, insufficient management support, concerns about the ability to scale Agile, need for development team support, and the perceived time and cost to make the transition. Finally, the paper offers concise recommendations to overcome each of the barriers as well as ideas for future research.
Recurrent hemopericardium with cardiac tamponade as an initial presentation of cardiac sarcoidosis
Authors: Pawaskar Aditya Sanjeev , Lanier Gregg M. , Prakash Priya , Ash Julia Y.
Published: November 2017

This case report illustrates an unusual presentation of recurrent hemopericardium with cardiac tamponade secondary to pulmonary sarcoidosis with extra-pulmonary cardiac involvement. It also demonstrates the usefulness of cardiac magnetic resonance (CMR) imaging as a non-invasive modality for the diagnosis of cardiac sarcoidosis.
The Representation of Bilingual Mental Lexicon and English Vocabulary Acquisition
Authors: Ying Zhang
Published: November 2017

This paper provides an overview of the theories on the organization and development of L1 mental lexicon and the representation mode of bilingual mental lexicon. It analyzes the structure and characteristics of Chinese EFL learners and their problems in English vocabulary acquisition. On the basis of this, it suggests that English vocabulary teaching should be adjusted to learners’ various proficiency levels at different stages. Learners should pay attention to the mediating role of Chinese, cultivate their English thinking pattern, and strengthen the development of in-depth vocabulary knowledge.
Recent African Refugees to Australia: Analysis of Current Refugee Services, a Case Study from Western Australia
Authors: Hancock Peter
Published: November 2017

In the last decade the number of African refugees arriving in Australia has increased significantly, to the extent to which by 2008 they outnumbered all other refugee and humanitarian entrants to Australia (for example, in 2004-2005 75% of all refugee and humanitarian entrants to Australia were from Africa). Existing service provision models have been found to be ill-equipped to cope with this sudden influx and have struggled to cope with the unique needs of African refugees (trauma, cultural needs, racism and longer settlement adjustment periods – compared to other groups) in particular. This paper is based on a data-base and literature analysis of the numbers, issues and problems faced by refugees in Western Australia. Its major aim is to provide researchers and policy-makers with a resource base from which they can further their understandings of the plight of refugees in developing nations. As such much of the paper is based on analysis of a large amount of literature and data from government agencies, designed to provide an exhaustive overview of refugees, their experiences and gaps in service provision in Western Australia.
PV Improved Power Using Off-Normal Sun Tracking
Authors: Musa Abdalla, , Hanan Abu Quba,
Published: November 2017

Harvested Power from two axes tracking Photovoltaic modules is analyzed and investigated for the objective of enhancing its reduced efficiency in hot to moderate climates. A novel proposed natural cooling of the modules that depends on optimizing the PV different dynamical models is presented. The optimized PV orientation angles for the tracking system revealed that exact normality of the sun rays over the PV module may not be the best setup! The wind speed and direction over the PV impacts the collector’s temperature and consequently the PV efficiency. Finally, the work was verified and validated using real collected data from a weather station in Jordan.