bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of the Hoa Binh Dam (Vietnam) on water and sediment budgets in the Red River basin and delta
Authors: Vu D. V. , Ouillon S. , Tran D. T. , La V. C.
Published: January 2014

Abstract. The Hoa Binh Dam, located on a tributary of the Red River in Vietnam, has a capacity of 9.45 × 109 m3 and was commissioned in December 1988. Although being important for flood prevention, electricity production, and irrigation in northern Vietnam, the Hoa Binh Dam has also highly influenced the suspended sediment distribution in the lower Red River basin, in the delta and in the coastal zone. Its impact was analysed from 50 yr dataset of water discharge and suspended sediment concentration (1960–2010) and the distribution of water and sediment across the nine mouths of the delta was calculated using the MIKE 11 numerical model before and after the dam settlement. Although water discharge at the delta inlet decreased by only 8.8%, the yearly suspended sediment flux dropped, on average from 119 to 43 × 106 t yr−1 at Son Tay near Hanoi, and from 85 to 35 × 106 t yr−1 in the river mouths. Water regulation has led to decreased water discharge in the wet season and increased water discharge in the dry season. Suspended sediment discharge proportionally increased in northern and southern estuaries and decreased through the main and central Ba Lat mouth. Tidal pumping, which causes a net sediment flux from the coast to the estuary at low discharge, is high in the northern delta, as a consequence of the high tidal range (up to 4.5 m in spring tide; diurnal tide). The shifts in the dynamic and characteristics of the turbidity maximum zone in the Cam-Bach Dang estuary are probably the cause of the enhanced sediment deposition in the Haiphong harbor. Along the coast, the reduced sedimentation rates are coincident with the lower sediment delivery that has been observed since the impoundment of the Hoa Binh Dam.
A satellite-based snow cover climatology (1985–2011) for the European Alps derived from AVHRR data
Authors: Hüsler F. , Jonas T. , Riffler M. , Musial J. P. , Wunderle S.
Published: January 2014

Abstract. Seasonal snow cover is of great environmental and socio-economic importance for the European Alps. Therefore a high priority has been assigned to quantifying its temporal and spatial variability. Complementary to land-based monitoring networks, optical satellite observations can be used to derive spatially comprehensive information on snow cover extent. For understanding long-term changes in alpine snow cover extent, the data acquired by the Advanced Very High Resolution Radiometer (AVHRR) sensors mounted onboard the National Oceanic and Atmospheric Association (NOAA) and Meteorological Operational satellite (MetOp) platforms offer a unique source of information. In this paper, we present the first space-borne 1 km snow extent climatology for the Alpine region derived from AVHRR data over the period 1985–2011. The objective of this study is twofold: first, to generate a new set of cloud-free satellite snow products using a specific cloud gap-filling technique and second, to examine the spatiotemporal distribution of snow cover in the European Alps over the last 27 yr from the satellite perspective. For this purpose, snow parameters such as snow onset day, snow cover duration (SCD), melt-out date and the snow cover area percentage (SCA) were employed to analyze spatiotemporal variability of snow cover over the course of three decades. On the regional scale, significant trends were found toward a shorter SCD at lower elevations in the south-east and south-west. However, our results do not show any significant trends in the monthly mean SCA over the last 27 yr. This is in agreement with other research findings and may indicate a deceleration of the decreasing snow trend in the Alpine region. Furthermore, such data may provide spatially and temporally homogeneous snow information for comprehensive use in related research fields (i.e., hydrologic and economic applications) or can serve as a reference for climate models.
Up, Up and Away! The Economics of Vertical Farming
Authors: Banerjee Chirantan , Adenaeuer Lucie
Published: January 2014

With rising population and purchasing power, demand for food and changing consumer preferences are building pressure on our resources. Vertical Farming, which means growing food in skyscrapers, might help to solve many of these problems. The purpose of this study was to construct a Vertical Farm and thereof investigate the economic feasibility of it. In a concurrent Engineering Study initiated by DLR Bremen, a farm, 37 floors high, was designed and simulated in Berlin to estimate the cost of production and market potential of this technology. It yields about 3,500 tons of fruits and vegetables and ca. 140 tons of tilapia fillets, 516 times more than expected from a footprint area of 0.25 ha due to stacking and multiple harvests. The investment costs add up to € 200 million, and it requires 80 million litres of water and 3.5 GWh of power per year. The produced food costs between € 3.50 and € 4.00 per kilogram. In view of its feasibility, we estimate a market for about 50 farms in the short term and almost 3000 farms in the long term. To tap the economic, environmental and social benefits of this technology, extensive research is required to optimise the production process.
Predicción del nivel de dificultad en una prueba estandarizada de comprensión de lectura: aportes desde la psicometría y la psicología cognitiva
Authors: Brizuela Armel , Montero-Rojas Eiliana
Published: January 2014

Esta investigación busca identificar posibles variables predictoras del nivel de dificultad de los ítems de comprensión de lectura utilizados en una prueba psicométrica estandarizada para la admisión a una institución universitaria. Se propusieron varios posibles predictores del nivel de dificultad, a saber: densidad proposicional, negaciones, estructura sintáctica, dificultad del vocabulario, presencia elementos de realce (palabras resaltadas tipográficamente), abstracción del ítem y grado de similitud entre opción correcta y texto relevante para resolver el ítem. Mediante el Modelo Logístico Lineal de Rasgo Latente se encontró que la cantidad de proposiciones, la estructura sintáctica y, fundamentalmente, la presencia de léxico difícil de comprender contribuyeron a la predicción del nivel de dificultad.
Regional contribution of CO2 and CH4 fluxes from the fluvial network in a lowland boreal landscape of Québec
Authors: Campeau Audrey , Lapierre Jean‐François , Vachon Dominic , del Giorgio Paul A.
Published: January 2014

Boreal rivers and streams are known as hot spots of CO2 emissions, yet their contribution to CH4 emissions has traditionally been assumed to be negligible, due to the spatially fragmented data and lack of regional studies addressing both gases simultaneously. Here we explore the regional patterns in river CO2 and CH4 concentrations (pCO2 and pCH4), gas exchange coefficient (k), and the resulting emissions in a lowland boreal region of Northern Québec. Rivers and streams were systematically supersaturated in both gases, with both pCO2 and pCH4 declining along the river continuum. The k was on average low and increased with stream order, consistent with the hydrology of this flat landscape. The smallest streams (order 1), which represent < 20% of the total river surface, contributed over 35% of the total fluvial greenhouse gas (GHG) emissions. The end of winter and the spring thaw periods, which are rarely included in annual emission budgets, contributed on average 21% of the annual GHG emissions. As a whole, the fluvial network acted as significant source of both CO2 and CH4, releasing on average 1.5 tons of C (CO2 eq) yr−1 km−2 of landscape, of which CH4 emissions contributed approximately 34%. We estimate that fluvial CH4 emissions represent 41% of the regional aquatic (lakes, reservoirs, and rivers) CH4 emissions, despite the relatively small riverine surface (4.3% of the total aquatic surface). We conclude that these fluvial networks in boreal lowlands play a disproportionately large role as hot spots for CO2 and more unexpectedly for CH4 emissions.
Contribution of local and remote anthropogenic aerosols to the twentieth century weakening of the South Asian Monsoon
Authors: Bollasina Massimo A. , Ming Yi , Ramaswamy V. , Schwarzkopf M. Daniel , Naik Vaishali
Published: January 2014

The late twentieth century response of the South Asian monsoon to changes in anthropogenic aerosols from local (i.e., South Asia) and remote (i.e., outside South Asia) sources was investigated using historical simulations with a state‐of‐the‐art climate model. The observed summertime drying over India is replaced by widespread wettening once local aerosol emissions are kept at preindustrial levels while all the other forcings evolve. Constant remote aerosol emissions partially suppress the precipitation decrease. While predominant precipitation changes over India are thus associated with local aerosols, remote aerosols contribute as well, especially in favoring an earlier monsoon onset in June and enhancing summertime rainfall over the northwestern regions. Conversely, temperature and near‐surface circulation changes over South Asia are more effectively driven by remote aerosols. These changes are reflected into northward cross‐equatorial anomalies in the atmospheric energy transport induced by both local and, to a greater extent, remote aerosols.
In situ measurements of ice saturation in young contrails
Authors: Kaufmann Stefan , Voigt Christiane , Jeßberger Philipp , Jurkat Tina , Schlager Hans , Schwarzenboeck Alfons , Klingebiel Marcus , Thornberry Troy
Published: January 2014

Relative humidity with respect to ice (RHi) is a major factor controlling the evolution of aircraft contrails. High‐resolution airborne H2O measurements in and near contrails were made at a rate of 4.2 Hz using the novel water vapor mass spectrometer AIMS‐H2O with in‐flight calibration during the CONtrail, volcano, and Cirrus ExpeRimenT (CONCERT) 2011. Three 2 min old contrails were sampled near 11 km altitude. Independent of the ambient supersaturation or subsaturation over ice, the mean of the RHi frequency distribution within each contrail is shifted toward ice saturation. This shift can be explained by the high ice surface area densities with corresponding RHi relaxation times on the order of 20 s, which lead to the fast equilibration of H2O between the vapor and ice phase. Understanding the interaction of water vapor with ice particles is essential to investigate the life cycle of contrails and cirrus.
Detection of spatially aggregated changes in temperature and precipitation extremes
Authors: Fischer E. M. , Knutti R.
Published: January 2014

Observed trends in the intensity of hot and cold extremes as well as in dry spell length and heavy precipitation intensity are often not significant at local scales. However, using a spatially aggregated perspective, we demonstrate that the probability distribution of observed local trends across the globe for the period 1960–2010 is clearly different to what would be expected from internal variability. We detect a distinct intensification of heavy precipitation events and hot extremes. We show that CMIP5 models generally capture the observed shift in the trend distribution but tend to underestimate the intensification of heavy precipitation and cold extremes and overestimate the intensification in hot extremes. Using an initial condition experiment sampling internal variability, we demonstrate that much of the local to regional differences in trends of extremes can be explained by internal variability, which can regionally mask or amplify the forced long‐term trends for many decades.
Spatial and temporal patterns of large‐scale droughts in Europe: Model dispersion and performance
Authors: Tallaksen Lena M. , Stahl Kerstin
Published: January 2014

This study explores the performance of a suite of off‐line, global (hydrological and land surface) models in mapping spatial and temporal patterns of large‐scale hydrological droughts in Europe from simulated runoff in the period 1963–2000. Consistent model behavior was found for annual variability in mean drought area, whereas high model dispersion was revealed in the weekly evolution of contiguous area in drought and its annual maximum. Comparison with nearly three hundred catchment‐scale streamflow observations showed an overall tendency to overestimate the number of drought events and hence underestimate drought duration, whereas persistence in drought‐affected area (weekly mean) was underestimated, noticeable for one group of models. The high model dispersion in temporal and spatial persistence of drought identified implies that care should be taken when analyzing drought characteristics from only one or a limited number of models unless validated specifically for hydrological drought.
The plasmaspheric plume and magnetopause reconnection
Authors: Walsh B. M. , Phan T. D. , Sibeck D. G. , Souza V. M.
Published: January 2014

We present near‐simultaneous measurements from two THEMIS spacecraft at the dayside magnetopause with a 1.5 h separation in local time. One spacecraft observes a high‐density plasmaspheric plume while the other does not. Both spacecraft observe signatures of magnetic reconnection, providing a test for the changes to reconnection in local time along the magnetopause as well as the impact of high densities on the reconnection process. When the plume is present and the magnetospheric density exceeds that in the magnetosheath, the reconnection jet velocity decreases, the density within the jet increases, and the location of the faster jet is primarily on field lines with magnetosheath orientation. Slower jet velocities indicate that reconnection is occurring less efficiently. In the localized region where the plume contacts the magnetopause, the high‐density plume may impede the solar wind‐magnetosphere coupling by mass loading the reconnection site.
Observation of local and conjugate ionospheric perturbations from individual oceanic lightning flashes
Authors: Gołkowski M. , Gross N. C. , Moore R. C. , Cotts B. R. T. , Mitchell M.
Published: January 2014

Very low frequency (VLF) remote sensing observations of multifaceted local and conjugate ionospheric perturbations from geographically identified and well‐characterized oceanic lightning discharges are presented for the first time. Lightning‐induced electron precipitation (LEP) events are shown to produce disturbances first in the conjugate hemisphere and subsequently in the hemisphere of the causative lightning discharge in agreement with theoretical predictions. A rough threshold peak current of ∼100 kA is identified for lightning discharges to generate LEP events for the geomagnetic conditions present during observations. The occurrence of early VLF events and the subsequent duration of their recovery do not seem to fit any simple metric of lightning discharge peak current or proximity to great circle path. Knowledge of the full spectral density of the lightning electromagnetic pulse, not just its peak current, and the subionospheric mode structure are likely necessary to determine if a specific lightning discharge will generate an early VLF perturbation.
Phase velocity tomography of surface waves using ambient noise cross correlation and array processing
Authors: Boué Pierre , Roux Philippe , Campillo Michel , Briand Xavier
Published: January 2014

Continuous recordings of ambient seismic noise across large seismic arrays allows a new type of processing using the cross‐correlation technique on broadband data. We propose to apply double beamforming (DBF) to cross correlations to extract a particular wave component of the reconstructed signals. We focus here on the extraction of the surface waves to measure phase velocity variations with great accuracy. DBF acts as a spatial filter between two distant subarrays after cross correlation of the wavefield between each single receiver pair. During the DBF process, horizontal slowness and azimuth are used to select the wavefront on both subarray sides. DBF increases the signal‐to‐noise ratio, which improves the extraction of the dispersive wave packets. This combination of cross correlation and DBF is used on the Transportable Array (USArray), for the central U.S. region. A standard model of surface wave propagation is constructed from a combination of the DBF and cross correlations at different offsets and for different frequency bands. The perturbation (phase shift) between each beam and the standard model is inverted. High‐resolution maps of the phase velocity of Rayleigh and Love waves are then constructed. Finally, the addition of azimuthal information provided by DBF is discussed, to construct curved rays that replace the classical great‐circle path assumption.
Time‐dependent modeling of slow slip events and associated seismicity and tremor at the Hikurangi subduction zone, New Zealand
Authors: Bartlow Noel M. , Wallace Laura M. , Beavan R. John , Bannister Stephen , Segall P.
Published: January 2014

We present a time‐dependent slip model of 12 slow slip events (SSEs) occurring in the Hikurangi margin of New Zealand during 2010 and 2011. This model is obtained by inverting daily GPS solutions from GeoNet's continuous GPS network on the North Island and northern South Island. We compare the properties of these SSEs to observations in Japan, Cascadia, and Mexico and find that Hikurangi SSEs have comparatively large amounts of slip (up to 27 cm), high slip rates (up to 1.4 cm/d), and a large range of depths (10–40 km), durations (7–270 days), and sizes (Mw 5.9–6.9). We further investigate the relationship between the Cape Turnagain SSE and an associated seismic swarm and find that observations are consistent with stress triggering outside the slowly slipping region; however, other explanations cannot be ruled out. We also compare slip during the long‐term Manawatu SSE with the tremor epicenters found by Ide (2012) and note that tremor locations are offset in the downdip direction relative to the slipping region, similar to observations in the Bungo Channel of Japan and Guerrero, Mexico.
Planetary boundary layer errors in mesoscale inversions of column‐integrated CO2 measurements
Authors: Lauvaux T. , Davis K. J.
Published: January 2014

Observing platforms of greenhouse gas column mole fractions using remote sensing instruments have enhanced the capability of carbon data assimilation systems at large scales and helped improve our understanding of the underlying processes involved in the exchange of carbon at the surface of the globe. In this study, we quantify the additional information carried by these measurements at finer scales and consider the impact of vertical transport errors in current modeling systems, one of the main sources of uncertainties in regional inverse flux estimates. Surface‐based column‐integrated sensors are shown to be a significant source of information to constrain local surface fluxes at fine scales. Gain and error reduction are only about 20% lower than for in situ instruments. Column measurements show less dependence on near‐field surface fluxes compared to in situ, with the error reduction being more homogeneously distributed. However, vertical transport errors still impact the flux retrievals, as with in situ measurements but to a lesser extent. Inverse fluxes from both types of measurements were affected by errors in vertical mixing and mean horizontal winds, with a larger impact on the inverse carbon balance using in situ measurements. The use of remote sensing measurements also appeared to constrain significantly the boundary concentrations, a critical limitation in current regional inversions. We finally performed a pseudo‐data experiment combining both types of instruments, creating an optimal observing network with a lower impact of planetary boundary layer transport errors on the surface fluxes and the boundary concentrations, and a more widely distributed reduction of the errors over the boundaries.
The structure of X‐ray emissions from triggered lightning leaders measured by a pinhole‐type X‐ray camera
Authors: Schaal M. M. , Dwyer J. R. , Arabshahi S. , Cramer E. S. , Lucia R. J. , Liu N. Y. , Rassoul H. K. , Smith D. M. , Matten J. W. , Reid A. G. , Hill J. D. , Jordan D. M. , Uman M. A.
Published: January 2014

We investigate the structure of X‐ray emissions from downward triggered lightning leaders using a pinhole‐type X‐ray camera (XCAM) located at the International Center for Lightning Research and Testing. This study builds on the work of Dwyer et al. (2011), which reported results from XCAM data from the 2010 summer lightning season. Additional details regarding the 2010 data are reported here. During the 2011 summer lightning season, the XCAM recorded 12 out of 17 leaders, 5 of which show downward leader propagation. Of those five leaders, one dart‐stepped leader and two chaotic dart leaders are the focus of this paper. These three leaders displayed unique X‐ray emission patterns: a chaotic dart leader displayed a diffuse structure (i.e., a wide lateral “spraying” distribution of X‐rays), and a dart‐stepped leader and a chaotic dart leader exhibited compact emission (i.e., a narrow lateral distribution of strong X‐ray emission). These two distinct X‐ray emission patterns (compact and diffuse) illustrate the variability of lightning leaders. Using Monte Carlo simulations, we show that the diffuse X‐ray source must originate from a diffuse source of energetic electrons or possibly emission from several sources. The compact X‐ray sources originate from compact electron sources, and the X‐ray source region radius and electric charge contained within the X‐ray source region were between 2 and 3 m and on the order of 10–4 C, respectively. For the leaders under investigation, the X‐ray source region average currents were determined to be on the order of 102 A.
Analysis of hydroclimatic variability and trends using a novel empirical mode decomposition: Application to the Paraná River Basin
Authors: Antico A. , Schlotthauer G. , Torres M. E.
Published: January 2014

The current understanding of hydroclimatic processes is largely based on time series analysis of observations such as river discharge. Although records of these variables are often nonlinear and nonstationary, they have been commonly analyzed by classical methods designed for linear and/or stationary data. This study investigates the possibility of analyzing hydroclimatic time series using a novel data‐driven method named Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), which is suitable for nonlinear and nonstationary signals. CEEMDAN is here applied to a monthly mean discharge record (1904–2010) of the Paraná River (South America). The results obtained in this way are interpreted by comparing them with CEEMDAN decompositions of other records such as climate index time series. It is found that Paraná flow modes consist of (i) annual and intraannual oscillations reflecting the rainfall seasonality of different Paraná Basin sectors, and (ii) interannual to interdecadal changes linked to climate cycles like El Niño/Southern Oscillation, the North Atlantic Oscillation, and the Interdecadal Pacific Oscillation. A nonlinear trend of Paraná discharge is found and reveals a monotonic increase that could be attributed to global warming and anthropogenic land‐cover changes. The spectral separation of modes obtained using CEEMDAN is cleaner than that achieved by the Ensemble Empirical Mode Decomposition technique. This makes it easier to interpret CEEMDAN results. Hence, CEEMDAN is proposed as a powerful method for extracting physically meaningful information from hydroclimatic data.
The VIIRS Cloud Mask: Progress in the first year of S‐NPP toward a common cloud detection scheme
Authors: Kopp Thomas J. , Thomas William , Heidinger Andrew K. , Botambekov Denis , Frey Richard A. , Hutchison Keith D. , Iisager Barbara D. , Brueske Kurt , Reed Bonnie
Published: January 2014

The Visible Infrared Imager Radiometer Suite (VIIRS) Cloud Mask (VCM) determines, on a pixel‐by‐pixel basis, whether or not a given location contains cloud. The VCM serves as an intermediate product (IP) between the production of VIIRS sensor data records and 22 downstream Environmental Data Records that each depends upon the VCM output. As such, the validation of the VCM IP is critical to the success of the Suomi National Polar‐orbiting Partnership (S‐NPP) product suite. The methods used to validate the VCM and the current results are presented in this paper. Detailed analyses of golden granules along with tools providing deep insights into granule performance, and specific cloud detection tests reveal the details behind a given granule's performance. Matchup results with CALIPSO, in turn, indicate the large‐scale performance of the VCM and whether or not it is meeting its specifications. Comparisons with other cloud masks indicate comparable performance for the determination of clear pixels. As of September 2013 the VCM is either meeting or within 2% of all of its documented requirements.
Deuterium excess in marine water vapor: Dependency on relative humidity and surface wind speed during evaporation
Authors: Benetti Marion , Reverdin Gilles , Pierre Catherine , Merlivat Liliane , Risi Camille , Steen‐Larsen Hans Christian , Vimeux Françoise
Published: January 2014

We provide the first continuous measurements of isotopic composition (δD and δ18O) of water vapor over the subtropical Eastern North Atlantic Ocean from mid‐August to mid‐September 2012. The ship was located mostly around 26°N, 35°W where evaporation exceeded by far precipitation and water vapor at 20 m largely originated from surface evaporation. The only large deviations from that occurred during a 2 day period in the vicinity of a weak low‐pressure system. The continuous measurements were used to investigate deuterium excess (d‐excess) relation to evaporation. During 25 days d‐excess was negatively correlated with relative humidity (r2 = 0.89). Moreover, d‐excess estimated in an evaporative model with a closure assumption reproduced most of the observed variability. From these observations, the d‐excess parameter seems to be a good indicator of evaporative conditions. We also conclude that in this region, d‐excess into the marine boundary layer is less affected by mixing with the free troposphere than the isotopic composition. From our data, the transition from smooth to rough regime at the ocean surface is associated with a d‐excess decrease of 5‰, which suggests the importance of the ocean surface roughness in controlling d‐excess in this region.
Arctic cryosphere response in the Geoengineering Model Intercomparison Project G3 and G4 scenarios
Authors: Berdahl Mira , Robock Alan , Ji Duoying , Moore John C. , Jones Andy , Kravitz Ben , Watanabe Shingo
Published: January 2014

We analyzed output from the Geoengineering Model Intercomparison Project for the two most “realistic” scenarios, which use the representative concentration pathway of 4.5 Wm−2 by 2100 (RCP4.5) as the control run and inject sulfate aerosol precursors into the stratosphere. The first experiment, G3, is specified to keep RCP4.5 top of atmosphere net radiation at 2020 values by injection of sulfate aerosols, and the second, G4, injects 5 Tg SO2 per year. We ask whether geoengineering by injection of sulfate aerosols into the lower stratosphere from the years 2020 to 2070 is able to prevent the demise of Northern Hemispere minimum annual sea ice extent or slow spring Northern Hemispere snow cover loss. We show that in all available models, despite geoengineering efforts, September sea ice extents still decrease from 2020 to 2070, although not as quickly as in RCP4.5. In two of five models, total September ice loss occurs before 2060. Spring snow extent is increased from 2020 to 2070 compared to RCP4.5 although there is still a negative trend in 3 of 4 models. Because of the climate system lag in responding to the existing radiative forcing, to stop Arctic sea ice and snow from continuing to melt, the imposed forcing would have to be large enough to also counteract the existing radiative imbalance. After the cessation of sulfate aerosol injection in 2070, the climate system rebounds to the warmer RCP4.5 state quickly, and thus, any sea ice or snow retention as a result of geoengineering is lost within a decade.
A worldwide analysis of spatiotemporal changes in water balance‐based evapotranspiration from 1982 to 2009
Authors: Zeng Zhenzhong , Wang Tao , Zhou Feng , Ciais Philippe , Mao Jiafu , Shi Xiaoying , Piao Shilong
Published: January 2014

A satellite‐based water balance method is developed to model global evapotranspiration (ET) through coupling a water balance (WB) model with a machine‐learning algorithm (the model tree ensemble, MTE) (hereafter WB‐MTE). The WB‐MTE algorithm was firstly trained by combining monthly WB‐estimated basin ET with the potential drivers (e.g., radiation, temperature, precipitation, wind speed, and vegetation index) across 95 large river basins (5824 basin‐months) and then applied to establish global monthly ET maps at a spatial resolution of 0.5° from 1982 to 2009. The global land ET estimated from WB‐MTE has an annual mean of 593 ± 17 mm for 1982–2009, with a spatial distribution consistent with previous studies in all latitudes but the tropics. The ET estimated by WB‐MTE also shows significant linear trends in both annual and seasonal global ET during 1982–2009, though the trends seem to have stalled after 1998. Moreover, our study presents a striking difference from the previous ones primarily in the magnitude of ET estimates during the wet season particularly in the tropics, where ET is highly uncertain due to lack of direct measurements. This may be tied to their lack of proper consideration to solar radiation and/or the rainfall interception process. By contrast, in the dry season, our estimate of ET compares well with the previous ones, both for the mean state and the variability. If we are to reduce the uncertainties in estimating ET, these results emphasize the necessity of deploying more observations during the wet season, particularly in the tropics.
Complexity signatures for short time scales in the atmosphere above Adventdalen, Svalbard
Authors: Hall C. M.
Published: January 2014

Atmospheric parameters from the troposphere above Adventdalen, Svalbard, 78°N, 16°E, are examined for signatures of complexity in their respective stochastic components over time scales from ~1 h to 1 year. Several approaches are used, all of which can estimate values of the generalized Hurst exponent, α, which can in turn be compared with each other and with similar independent characterizations, usually via the classic Hurst exponent, H, obtained from location‐specific and globally averaged time series. For tropopause altitude, the stochastic component exhibits the signature of a persistent fractional Gaussian noise (fGn) with α ≈ 0.75. For surface air temperature, the indications are for fractional Brownian motion (fBm) with α ≈ 1.4. Using recent high time‐resolution data from a single high‐latitude location, this identification of fBm is relevant for short‐term memory as opposed to findings from many other studies addressing possible long‐term memory, which demonstrate fGn with α = H ≈ 0.7. Furthermore, the lack of similarity between the results for surface air temperature and tropopause altitude suggests that different underlying processes are responsible for stochastic variability.
Modeling aeolian erosion in presence of vegetation
Authors: Dupont S. , Bergametti G. , Simoëns S.
Published: January 2014

Semiarid landscapes are characterized by vegetated surfaces. Understanding the impact of vegetation on aeolian soil erosion is important for reducing soil erosion or limiting crop damage through abrasion or burial. In the present study, a saltation model fully coupled with a large‐eddy simulation airflow model is extended to vegetated landscapes. From this model, the sensitivity of sand erosion to different arrangements and type of plants (shrub versus tree) representative of semiarid landscapes is investigated and the wind erosion reduction induced by plants is quantified. We show that saltation processes over vegetated surfaces have a limited impact on the mean wind statistics, the momentum extracted from the flow by saltating particles being negligible compared to that extracted by plants. Simulated sand erosion patterns resulting from plant distribution, i.e., accumulation and erosion areas, appear qualitatively consistent with previous observations. It is shown that sand erosion reduction depends not only on vegetation cover but also on plant morphology and plant distribution relative to the mean wind direction. A simple shear stress partitioning approach applied in shrub cases gives similar trends of sand erosion reduction as the present model following wind direction and vegetation cover. However, the magnitude of the reduction appears significantly different from one approach to another. Although shrubs trap saltating particles, trees appear more efficient than shrubs to reduce sand erosion. This is explained by the large‐scale sheltering effect of trees compared to the local shrub one.
Alaska tidewater glacier terminus positions, 1948–2012
Authors: McNabb R. W. , Hock R.
Published: January 2014

A significant portion of the world's glacier ice drains through tidewater outlets, though much remains unknown about the response to recent climate change of tidewater glaciers. We present a 64 year record of length change for 50 Alaska tidewater glaciers. We use U.S. Geological Survey topographic maps to provide a base length for glaciers before 1970. Using all available cloud‐free Landsat images, we manually digitize calving front outlines for each glacier between 1972 and 2012, resulting in a total of more than 10,000 outlines. Tidewater glacier lengths vary seasonally; focusing on the 36 glaciers terminating in tidewater throughout the study period, we find a mean (± standard deviation) seasonal variation of 60± 85 m a−1. We use these oscillations to determine the significance of interannual changes in glacier length. All 36 glaciers underwent at least one period (≥1 year) of significant advance or retreat; 28 glaciers underwent at least one period of both significant advance and retreat. Over the entire period 1948–2012, 24 of these glaciers retreated a total (± uncertainty) of 107.95±0.29 km, 11 advanced a total of 7.71±0.20, and one (Chenega Glacier) did not change significantly. Retreats and advances are highly variable in time; several glaciers underwent rapid, short‐term retreats of a few years duration. These retreats occurred after large changes in summer sea surface temperature anomalies; further study is needed to determine what triggered these retreats. No coherent regional behavior signal is apparent in the length record, although two subregions show a coherence similar to recent observations in Greenland.
Taliks in relict submarine permafrost and methane hydrate deposits: Pathways for gas escape under present and future conditions
Authors: Frederick J. M. , Buffett B. A.
Published: January 2014

We investigate the response of relict Arctic submarine permafrost and gas hydrate deposits to warming and make predictions of methane gas flux to the water column using a 2‐D multiphase fluid flow model. Exposure of the Arctic shelf during the last glacial cycle formed a thick layer of permafrost, protecting hydrate deposits below. However, talik formation below paleo‐river channels creates permeable pathways for gas migration from depth. An estimate of the maximum gas flux at the present time for conditions at the East Siberian Arctic Seas is 0.2047 kg yr−1 m−2, which produces a methane concentration of 142 nM in the overlying water column, consistent with several field observations. For conditions at the North American Beaufort Sea, the maximum gas flux at the present time is 0.1885 kg yr−1 m−2, which produces a methane concentration of 78 nM in the overlying water column. Shallow sediments are charged with residual methane gas after venting events. Sustained submergence into the future should increase gas venting rate roughly exponentially as sediments continue to warm. Studying permafrost‐associated gas hydrate reservoirs will allow us to better understand the Arctic's contribution to the global methane budget and global warming.
Flexural response of a continental margin to sedimentary loading and lithospheric rupturing: The mountain ridge between the Levant Basin and the Dead Sea Transform
Authors: Steinberg J. , Gvirtzman Z. , Garfunkel Z.
Published: January 2014

During the past 37 Myr the Levant Basin subsided under a 6 km sedimentary section while the adjacent area, Israel's mountainous backbone (Judea Hills), emerged to an elevation of ~1 km above sea level. What was the flexural contribution of offshore loading to the inland uplift that was also affected at that time by widespread geodynamic heating and uplifting? This question becomes particularly challenging considering that in the middle of this period the lithosphere adjacent to the basin (100–200 km east) ruptured and a new plate boundary was formed along the Dead Sea Transform (DST). How did this influence the strength of the lithosphere, and how did it change the shape of the flexure? We model the flexure caused by offshore sedimentary loading in two phases. The pre‐DST phase applies a flexural solution for an elastic plate without lithospheric rupturing (infinite boundaries). The post‐DST phase applies a flexural solution of an elastic plate with a free edge, set to resemble a lithosphere with no friction, and free to move vertically. The apparently unrealistic free edge simplification for a plate boundary provides an upper limit for the uplift. It is shown that before the initiation of the DST the flexural effect of the offshore loading on the inland region was negligible, and thus, most of the observed inland uplift should be explained in terms of deep‐seated tectonic processes. On the contrary, the last phase of uplift postdating the formation of the DST was influenced by flexural loading offshore that was intensified near the plate edge.
Influence of temperature on the phase inversion of chlorinated polypropylene
Authors: Ma Xiaoyang , Qiao Zemin , Huang Zhifeng , Jing Xinli , Gu Chaohui , Tang Hanliang
Published: January 2014

In this study, the maleic anhydride modified chlorinated polypropylene (MCPP) resin was emulsified by mixed ionic surfactants comprising sodium dodecyl sulfate (SDS) and sulfonated castor oil (SCO). The influence of temperature on the morphology of emulsion was studied through transitional and catastrophic inversion methods. The transitional inversion of emulsion from water‐in‐oil (W/O) to oil‐in‐water (O/W) was triggered by decreasing the temperature and the catastrophic inversion was achieved by increasing the weight fraction of water. The results of transitional and catastrophic inversion both indicated that the phase inversion of “ionic surfactant–MCPP–water” system is easier to trigger at low temperatures than at high temperatures, which could be interpreted by the thermodynamic and hydrodynamic theory. Incomplete phase inversion occurred at low temperatures when the volume of water phase was small and emulsions with small particle size and narrow particle size distribution could only be obtained at an intermediate temperature. These results are of great importance for the preparation of stable polymer emulsions in food, cosmetics and paints industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40325.
A double‐blind, randomized, ascending, multiple‐dose study of bazedoxifene in healthy postmenopausal women
Authors: McKeand William E. , Orczyk Gayle P. , Ermer James C. , Chines Arkadi A.
Published: January 2014

Bazedoxifene is a novel selective estrogen receptor modulator in clinical development for the prevention and treatment of postmenopausal osteoporosis. This phase 1, double‐blind, randomized, placebo‐controlled study (N = 107) of healthy postmenopausal women examined the pharmacokinetics and safety/tolerability profile of multiple doses of bazedoxifene (1, 2.5, 5, 10, 20, 40, and 80 mg) administered orally once daily for 30 days. Bazedoxifene demonstrated a half‐life of 25 to 30 hours, reached steady state within 7 days, and exhibited linear pharmacokinetics over a dose range of 5–80 mg. Fibrinogen levels decreased with bazedoxifene doses of 5 mg and greater; these changes were significant for bazedoxifene 20, 40, and 80 mg (P ≤ .05 vs placebo), but were not dose dependent. Bazedoxifene was associated with increased levels of sex hormone‐binding globulin, thyroxine‐binding globulin, and cortisol‐binding globulin (CBG); only increases in the levels of CBG appeared to be dose related. Bazedoxifene was safe and well tolerated within the tested dose range. Bazedoxifene showed no differences from placebo in adverse event reports, vital sign measurements, or electrocardiogram findings.
Time-dependent relative potency factors for polycyclic aromatic hydrocarbons and their derivatives in the H4IIE-luc bioassay
Authors: Larsson Maria , Hagberg Jessika , Giesy John P. , Engwall Magnus
Published: January 2014

The H4IIE-luc transactivation bioassay for aryl hydrocarbon receptor (AhR) agonists was used to investigate the relative potency factors (REPs) of 22 individual polycyclic aromatic hydrocarbons (PAHs) and their oxygenated-, methylated-, and N-containing derivatives (azaarenes), which are often present in PAH-contaminated soils. Naphthacene and dibenz[ah]acridine exhibited greater AhR-mediated potency, whereas lesser molecular–weight azaarenes were less potent AhR agonists. Six oxygenated PAHs had calculable REPs, but their potencies were less than their parent PAHs. Unlike the parent, unsubstituted PAHs, oxidation of methylated PAHs seemed to increase the AhR-mediated potency of the compounds, with 2-methylanthracene-9,10-dione being almost 2 times more potent than 2-methylanthracene. Both bioassay and gas chromatography–mass spectrometry analysis were used to examine the exposure time–dependent effects on the REPs at 24 h, 48 h, and 72 h of exposure in the H4IIE-luc transactivation bioassay. Changes in concentrations of 5 compounds including the model reference 2,3,7,8-tetrachlorodibenzo-p-dioxin in the cell culture wells were measured, and the amounts in the cell medium, in the cells, and adsorbed to the wells was determined and the influence on the REPs was studied. Declining REP values with increased duration of exposure were shown for all compounds, which we concluded were a consequence of the metabolism of PAHs and PAH derivatives in H4IIe-luc cells. The present study provides new knowledge regarding the degradation and distribution of compounds in the wells during exposure. Environ Toxicol Chem 2014;33:943–953. © 2014 SETAC
Disruption of negative feedback loop between vasohibin-1 and vascular endothelial growth factor decreases portal pressure, angiogenesis, and fibrosis in cirrhotic rats
Authors: Coch Laura , Mejias Marc , Berzigotti Annalisa , Garcia-Pras Ester , Gallego Javier , Bosch Jaime , Mendez Raul , Fernandez Mercedes
Published: January 2014

Pathological angiogenesis represents a critical hallmark for chronic liver diseases. Understanding the mechanisms regulating angiogenesis is essential to develop new therapeutic strategies that specifically target pathological angiogenesis without affecting physiological angiogenesis. Here we investigated the contribution and therapeutic impact of the endogenous angioinhibitor vasohibin-1 in portal hypertension and cirrhosis. The spatiotemporal expression profiling of vasohibin-1 and its relationship with vascular endothelial growth factor (VEGF), angiogenesis, and fibrogenesis was determined through the analysis of human cirrhotic liver specimens, widely accepted in vivo animal models of portal hypertension and cirrhosis, and in vitro angiogenesis assays. Effects of vasohibin-1 overexpression by adenoviral-mediated gene transfer on angiogenesis, fibrogenesis, and portal hypertension-associated hemodynamic alterations were also studied in rats. We found that vasohibin-1 and VEGF are up-regulated, in mesentery and liver, in cirrhotic and precirrhotic portal hypertensive rats and cirrhosis patients. Our results are consistent with vasohibin-1/VEGF cascades being spatially and temporally coordinated through a negative-feedback loop driving pathological angiogenesis. Paradoxically, further overexpression of vasohibin-1 by adenoviral gene transfer exerts multifold beneficial effects in portal hypertension and cirrhosis: reduction of pathologic angiogenesis, attenuation of liver fibrogenesis partly mediated through inhibition of hepatic stellate cell activation, and significant decreases in portocollateralization, splanchnic blood flow, portohepatic resistance, and portal pressure. The explanation for this apparent contradiction is that, unlike endogenous vasohibin-1, the ectopic overexpression is not regulated by VEGF and therefore disrupts the negative-feedback loop, thus generating constant, but lower levels of VEGF synthesis sufficient to maintain vascular homeostasis but not pathological angiogenesis. Conclusion: Our study provides evidence that vasohibin-1 regulates portal hypertension-associated pathological angiogenesis and highlights that increasing vasohibin-1 might be a promising novel therapeutic strategy for portal hypertension and cirrhosis. (Hepatology 2014;60:633–647)
A novel systemically administered toll‐like receptor 7 agonist potentiates the effect of ionizing radiation in murine solid tumor models
Authors: Adlard Amy L. , Dovedi Simon J. , Telfer Brian A. , Koga‐Yamakawa Erina , Pollard Charlotte , Honeychurch Jamie , Illidge Timothy M. , Murata Masashi , Robinson David T. , Jewsbury Philip J. , Wilkinson Robert W. , Stratford Ian J.
Published: January 2014

Although topical TLR7 therapies such as imiquimod have proved successful in the treatment of dermatological malignancy, systemic delivery may be required for optimal immunotherapy of nondermatological tumors. We report that intravenous delivery of the novel small molecule TLR7 agonist, DSR‐6434, leads to the induction of type 1 interferon and activation of T and B lymphocytes, NK and NKT cells. Our data demonstrate that systemic administration of DSR‐6434 enhances the efficacy of ionizing radiation (IR) and leads to improved survival in mice bearing either CT26 or KHT tumors. Of the CT26 tumor‐bearing mice that received combined therapy, 55% experienced complete tumor resolution. Our data reveal that these long‐term surviving mice have a significantly greater frequency of tumor antigen specific CD8+ T cells when compared to age‐matched tumor‐naïve cells. To evaluate therapeutic effects on spontaneous metastases, we showed that combination of DSR‐6434 with local IR of the primary tumor significantly reduced metastatic burden in the lung, when compared to time‐matched cohorts treated with IR alone. The data demonstrate that systemic administration of the novel TLR7 agonist DSR‐6434 in combination with IR primes an antitumor CD8+ T‐cell response leading to improved survival in syngeneic models of colorectal carcinoma and fibrosarcoma. Importantly, efficacy extends to sites outside of the field of irradiation, reducing metastatic load. Clinical evaluation of systemic TLR7 therapy in combination with IR for the treatment of solid malignancy is warranted.