bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracting icebergs freeboard from the shadows in Landsat-8 panchromatic images
Authors: Guan Zhenfu , Liu Yan
Published: March 2020

Abstract: The iceberg freeboard is an important geometric parameter for measuring the thickness of the iceberg and then estimating its volume. Based on the fact that the iceberg can cast elongated shadow on the surface of sea ice in winter, this paper proposes a method to measure the iceberg freeboard using shadow length and the predefined or estimated solar elevation angle. Three Landsat-8 panchromatic images are selected to test our method, with center solar elevation angle of respectively 5.43°, 7.49°and 11.01° on August 29, September 7, and 16 September in 2016. Shadow lengths of five isolated tabular icebergs are automatically extracted to calculate the freeboard height. For the accuracy assessment, we use the matching points at the different time as cross validation. The results show that the measurement error of shadow length is less than one pixel. When the sun elevation angle is lower than 11.01°, the Root Mean Square Error (RMSE) of the iceberg freeboard from the panchromatic 15 m image is less than 2.0 m, and the Mean Absolute Error (MAE) is less than 1.5 m. Such experiment shows that: under the angle of low solar elevation in winter, the landsat-8 panchromatic 15 m image can be used for high-precision measurement of the iceberg freeboard, and has the potential to measure the Antarctic iceberg freeboard in large scale.

Key words: Antarctic, icebergs, freeboard, shadow altimetry, Landsat-8

 
The asymmetric eddy-background flow interaction in the North Pacific storm track
Authors: Zhao Yuan-Bing
Published: March 2020

Using a recently developed methodology, namely, the multiscale window transform (MWT), and the MWT-based theory of canonical transfer and localized multiscale energetics analysis, we investigate in an eddy-following way the nonlinear eddy-background flow interaction in the North Pacific storm track, based on the ERA40 reanalysis data from ECWMF. It is found that more than 50% of the storms occur on the northern flank of the jet stream, about 40% are around the jet center, and very few (less than 5%) happen on the southern flank. For storms near or to the north of the jet center, their interaction with the background flow is asymmetric in latitude. In higher latitudes, strong downscale canonical available potential energy transfer happens, especially in the middle troposphere, which reduces the background baroclinicity and decelerates the jet; in lower latitudes, upscale canonical kinetic energy transfer intensifies at the jet center, accelerating the jet and enhancing the middle-level baroclinicity. The resultant effect is that the jet strengthens but narrows, leading to an anomalous dipolar pattern in the fields of background wind and baroclinicity. For the storms on the southern side of the jet, the baroclinic canonical transfer is rather weak. On average, the local interaction begins from about 3 days before a storm arrives at the site of observation, achieves its maximum as the storm arrives, and then weakens.
Multi-temporal Spaceborne InSAR technique to compensate Vertical Land Motion in Sea Level Change records: A case study of Tide gauges in Korean Peninsula
Authors: Palanisamy Vadivel Suresh Krishnan , Kim Duk-jin , Jung Jungkyo , Cho Yang-Ki
Published: March 2020

Relative sea-level changes observed by tide gauges are commonly corrected for several components including crustal displacement, ocean dynamics, and vertical land motion. Vertical Land Motion (VLM) due to local land hydrology is a crucial component that observed as localized ground motion and varies with each tide gauges. Permanent GNSS stations are used to measure the VLM trend at tide gauges, however, only few tide gauges are equipped with collocated GNSS stations. Multi-temporal InSAR analysis provides ground displacements in both the spatial and temporal domains. Therefore, in our study, we applied the spaceborne Interferometric SAR technique to measure the local ground motion using Sentinel-1 SAR data. The Korean peninsula is surrounded by the East Sea/Sea of Japan, the Yellow Sea and the East China Sea have continuously monitoring tide gauges with a record length of more than 30 years. We acquire C-band Sentinel-1 SAR data (both ascending and descending mode) over the Korean Peninsula during 2014/11 and 2019/04. We estimate the high-resolution (~ 10 m) land motion at tide gauges (mm-level accuracy) over these 21 tide gauges and, compared with available collocated GNSS observations. 2D displacements (vertical and horizontal) are derived from ascending and descending mode InSAR displacements. The linear trend of VLM observed from our InSAR estimates is used to compensate for the relative velocity of sea-level changes observed from tide gauges.
Atmospheric Lifetimes of Halogenated Hydrocarbons: Laboratory Measurements and Improved Estimations from an Analysis of Modeling Results.
Authors: Orkin Vladimir , Kurylo Michael , Fleming Eric
Published: March 2020

Reactions with hydroxyl radicals and photolysis are the main processes dictating a compound’s residence time in the atmosphere for a majority of trace gases.  In case of very short-lived halocarbons their reaction with OH dictates both the atmospheric lifetime and active halogen release.  Therefore, the accuracy of OH kinetic data is of primary importance for the comprehensive modeling of a compound’s impact on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP), each of which are dependent on the atmospheric lifetime of the compound.

 

Atmospheric modeling provides total lifetimes for a number of compounds as well as their partial lifetimes due to specific photochemical removal process (reactions with OH in the troposphere, reactions with OH in the stratosphere, reactions with O(1D), and UV photolysis), and partial lifetimes associated with the atmospheric removal regions (troposphere and stratosphere).  We have analyzed these results in an effort to find a correlation useful for estimating the lifetimes of other atmospheric trace gases based only on laboratory data of their photochemical properties.  Based on this analysis, we suggest an improved semi-empirical approach for deriving a “best” value of the total atmospheric lifetime due to photochemical removal processes based on laboratory derived photochemical properties of a compound, which is consistent with both empirically derived tropospheric lifetime of Methyl Chloroform and results of rigorous atmospheric modeling.  These aspects will be illustrated in this presentation for a variety of atmospheric trace gases.

 

The ability to conduct high accuracy laboratory determinations of OH reaction rate constants over the temperature range of atmospheric interest, thereby decreasing the uncertainty of input kinetic data to 2-3% will be demonstrated as well.
Potential of nature-based solutions for creating resourceful circular cities
Authors: Langergraber Günter , Atanasova Natasa
Published: March 2020

The COST Action Circular City (CA17133; "Implementing nature-based solutions for creating a resourceful circular city") aims to establish a network testing the hypothesis that a circular flow system that implements nature-based solutions (NBS) for managing nutrients and resources within the urban biosphere will lead to a resilient, sustainable and healthy urban environment. To date, most NBS are implemented serving only one single purpose. Adopting the concept of circular economy by combining different types of services and returning resources to the city, would increase the benefits gained for urban areas.

The Action's main output will be a guideline on combined NBS and circular economy possibilities within the urban environment. The work to achieve this will be carried out in five working groups (WGs):

WG1 "Built environment" investigates the NBS - circular economy aspect on building and settlement level with the main focus on vegetated building materials and resources to be obtained from the corresponding NBS.

WG2 "Sustainable urban water utilization" considers the implementation of a save and functional water cycle within the urban biosphere, defines available resources within the water flow, performs risk assessment on urban water and evaluates NBS for storm water management and waste water treatment.

WG3 "Resource recovery" aims to transform implemented NBS for mitigation or treatment purposes to sources for a variety of resources to be harvested, used, reused and recycled.

WG4 "Urban Farming" facilitates the implementation of urban farming with main purpose of food production within a city, but additionally paying close attention to other resources available from urban farming, usually considered waste.

Last but not least, WG5 "Transformation tools" coordinates and leads the interdisciplinary activities between the WGs with the main aim to facilitate implementation of NBS in circular cities by 1) investigate performance-based assessment tools, 2) developing simplified tools and information for stakeholders, and 3) establish public relations strategies and approaches.

The contribution will present the results already achieved by the WGs by summarizing main results from the review papers each WG has produced.
The Global Warming By Using The Experimental Methods Within Project-Based Learning Approach
Authors: Öncü Gulperi Selcan
Published: March 2020

In recent times we have often received news such as about melting glaciers, sudden and torrential rain, storms, increased atmospheric temperatures, and forest fires. We have also observed some of these phenomena in our immediate vicinity. There is a frequently used expression among the public, 'the seasons are shifting'. 

Students have asked the reasons why these changes have been occurring and what about changes between the past and present. In order to understand these changes we all know that they need to understand global warming in the first place. To help them with this as an science teacher I have guided them to be capable of using experimental methods within project-based learning approaches. First they did preliminary literature surveys and then they designed an experiment. In the experiment, they tested the hypothesis that the water inside the bell JAR, which is coated with black cardboard, heats up more than the transparent one. In this way they began to investigate climate change due to greenhouse gases. 

In the experiment, two bell glasses were used to represent the atmosphere layers. One was intermittently covered with pieces cut out of black cardboard. Black cardboard was used to represent the greenhouse gas due since the black colour absorbs light. Two beakers of the same size were used, filled with water. A thermometer was placed inside and bell jars were turned upside down and put over the beakers. The two thermometers were used to measure the water temperature inside the beakers. 

The first apparatus is the control group (inside uncovered). The second apparatus is the experimental group (covered with independent black cardboard). In the experimental and observation stage, the independent variable is the bell jar; the dependent variable is the water temperature. The constant variables are the size of the jar, the size of the beaker, the amount of water and the ambient conditions. 

Having set up the apparatus, the initial temperature of water was measured and recorded. Students carried out the experiment on a sunny day by placing the apparatus in a sun-covered field. They recorded the data in the tables they completed periodically. Then they shared the results with participants at the science festival. 

In this way they began to investigate the impact of greenhouse gases on climate change.
The role of fault offset in induced seismicity potential
Authors: Vilarrasa Victor , Parisio Francesco , Makhnenko Roman , Wu Haiqing , Rahimzadeh Kivi Iman
Published: March 2020

Geological media is envisioned as a strategic resource to store large volumes of CO2 and mitigate climate change. Geo-energy applications, such as geologic carbon storage, geothermal energy, and subsurface energy storage, involve injection and extraction of fluids that cause pressure diffusion. Pore pressure changes may induce seismicity, especially in faults that intersect the injection formation or are hydraulically connected with it. We numerically study with finite element analysis of coupled hydro-mechanical conditions how fault stability is affected by fluid injection into a porous aquifer that is overlaid and underlain by low permeability clay-rich formations. We model a layered sedimentary basin with alternating soft and low permeability with stiff and high permeability formations and include the crystalline basement at the bottom. Additionally, a low permeability steep fault, whose offset ranges from zero to the reservoir thickness, crosses the system. We consider a normal faulting stress regime typical of extensional environments. Simulation results show that the reservoir pressurization as a result of fluid injection causes significant stress changes around the fault that affect its stability. The stress changes depend on the stiffness of the rock juxtaposed to the pressurized reservoir. If there is no offset, the rock is stiff on both sides of the fault, inducing a homogeneous horizontal total stress increase along the thickness of the reservoir. As a result, the deviatoric stress becomes smaller and the induced seismicity potential is low. As the fault offset increases, some part of the base rock gets juxtaposed to the pressurized reservoir. The soft base rock deforms more than the reservoir rock in response to the reservoir expansion, inducing a lower horizontal total stress. Thus, fault stability reduces when the pressurized reservoir rock is juxtaposed with the softer base rock. This finding shows that the induced seismicity potential may increase with the fault offset.
Ophiolite carbonation: Constraints from listvenite core BT1B, Oman Drilling Project
Authors: Plümper Oliver , Beinlich Andreas , Boter Esmée , Müller Inigo A. , Kourim Fatma , Ziegler Martin , Harigane Yumiko , Lafay Romain , Kelemen Peter B. , Project Science Team the Oman Drilling
Published: March 2020

The widespread occurrence of the quartz–carbonate alteration assemblage (listvenite) in ophiolites indicates that ultramafic rock represents an effective sink for dissolved CO2. However, the understanding of the carbonation mechanisms is almost exclusively based on surface samples, which adds significant uncertainty to the interpretation of fossil hydrothermal systems. Here we present novel insight into the reaction textures and mechanisms of ultramafic rock carbonation obtained from the 300 m deep BT1B drill hole, ICDP Oman Drilling Project. Hole BT1B recovered continuous drill core intersecting surface alluvium, 200 meters of altered ultramafic rock comprising serpentinite and listvenite, and 100meters of the underlying metamorphic sole. The ultramafic part of BT1B is dominated by listvenite with only two thin intercalated serpentinite bands at 90 m and 180 m depth. Microstructural analyses indicate an evolution beginning with non-equilibrium growth of spheroidal carbonate composed of interlayered magnesite and dolomite in the completely serpentinized harzburgite, and magnesite and Ca-magnesite in the listvenite. Carbonate spheroids are characterized by sectorial zoning resulting from radially oriented low-angle boundaries. In the listvenite spheroidal carbonate is overgrown by euhedral magnesite indicative of near-equilibrium growth. Carbonate clumped isotope thermometry indicates carbonate crystallization predominantly between 100°C and 200°C. The strong macroscopic brecciation and veining of listvenite indicate that carbonation was facilitated by significant tectonic deformation allowing for infiltration of reactive fluids over an extended duration.
An application of super ensemble simulation with appropriate bias correction for river planning in Japan
Authors: Watanabe Satoshi
Published: March 2020

In this study, a methodology that uses super ensemble simulation with appropriate bias correction for river planning was proposed. The Database for Policy Decision-Making for Future Climate Change (d4PDF) is a super ensemble experiments that comprise over 1000-year output have been conducted. The d4PDF provides regional downscaling simulation that focuses around Japan. It is expected that the impact assessments of climate changes on various fields considering uncertainly are conducted.

The impact of climate change on floods is a serious issue. In Japan, all class A river has design rainfall for the river planning that is defined considering historical observations of precipitation that happens once in several hundred years, which the planning year is different depending on the situation of a river. The design rainfall provides the fundamental information for planning river management.  The Ministry of Land, Infrastructure, Transportation and Tourism defines the value of the rainfall in the planning year in each class A river basin by considering the hydro-meteorological and social characteristics of each basin. As the design rainfall was defined in the mid-1900s for most of the rivers, the method to estimate precipitation in the planning year was conducted with limited observation data using extreme statistical value. The super ensemble simulation data is expected to contribute for the decision making with appropriate setting of design rainfall.

We proposed a method to correct the bias of super ensemble simulation and estimated the design rainfall in 47 river basins selected from class A river basins. The estimated design rainfall was compared between the one estimated with super ensemble simulation and the one estimated with conventional approach. The spread of results oriented from super ensemble simulation indicated that uncertainly of design rainfall estimated with conventional approach was so high that the consideration of uncertainty is necessary for river planning. The experiments indicated that the use of super ensemble simulation with appropriate bias correction could provide knowledge that aids us in understanding the hydrological extremes.
Assessment of Distributed Snow Modeling using Ground and Remote Sensing Data in Mountainous Eastern Turkey
Authors: Sorman Ali Arda , Ertas Mustafa Cansaran
Published: March 2020

Water has an essential effect on climate change, global warming, drought, flood and all kinds of living life as a result of the continuous movement between earth and atmosphere. In high latitude and elevated regions of the world, most of the annual total precipitation occurs in the form of snow and snow melting provides the majority of usable water. Due to the large impact of snow cover on water/energy balance, the quantity, spatial and temporal distribution of the snow is very important in the hydrological system.

Turkey is the 4th highest country in Europe, after Andorra, Georgia and Switzerland, with an average elevation of 1140 m. Therefore, snow frequently occurs and may stay on the ground more than half of the year especially in the north, east and central regions. Snowmelt runoff in the mountainous eastern part of Turkey, where large dams are located, is of great importance as it constitutes 2/3 in volume of the yearly total runoff during spring and early summer months. Therefore, determining the amount and timing of snowmelt is of utmost value in order to use the water resources of the country in an optimal manner.

In this study; conceptual snowpack model SNOW-17, which has a common usage in the literature, is applied in a fully distributed manner in the Upper Euphrates Basin. SNOW-17 is a conceptual model using air temperature as the sole index to determine the energy exchange across the snow-air interface. The model results of snowpack components, such as height of snow (HS) and snow water equivalent (SWE) are evaluated with independent pointwise in-situ measurements and spatially distributed satellite images. The snow model results show an average success of 0.81 and 0.66 in terms of Nash-Sutcliffe Efficiency (NSE) for the calibration and validation periods, respectively. In addition, the extreme snowfall and early snowmelt event that occurred in 2004 snow season is further evaluated by the snow model and satellite products.
Artificial acceleration of the Brewer-Dobson circulation due to stratospheric cooling
Authors: Eichinger Roland , Sacha Petr
Published: March 2020

There is robust observational evidence that the troposphere is warming and the stratosphere is cooling in response to the radiative forcing of anthropogenic greenhouse gas (GHG) emissions. Temperature changes directly influence the vertical structure of the atmopshere. Numerous studies have analysed the thermal expansion of the troposphere, in particular the tropopause rise and its interaction with the Brewer-Dobson circulation (BDC). Stratospheric cooling, however, reduces the upward shift of pressure levels with increasing altitude so that it reverses sign at some height, leading to a downward shift of the middle to upper stratosphere. This "stratospheric shrinkage“ effect is a strong and robust feature of climate change and it is well documented through observations. Still, literature on this effect is relatively sparse and its impact on stratospheric dynamics is generally neglected.

In this study, we report and quantify the uncertainty in residual upward velocity (w*) trends that arises from the implicit neglection of stratospheric shrinkage in the data model request for the Chemistry-Climate Model Initiative part 1 (CCMI-1). Tropical w* is often taken as a proxy for diagnosing the BDC strength. In the data request, a constant scale height is assumed for conversion of w* from Pa/s to m/s . However, the scale height significantly decreases over time in the climate simulations as a result of stratospheric shrinkage.

We show that stratospheric cooling enhances the w* trends if the unit conversion is made with constant scale height, which can be misinterpreted as BDC acceleration. We quantify this effect to account for around 20% of the w* trend across the 21st century, consistently among the CCMI-1 climate projection simulations. Past studies that based w* trend analyses on these data therefore made a 20% error. Moreover, we call attention that other dynamical diagnostics are affected by the neglection of stratospheric shrinkage too and also the data requests of other multi-model assessments use the constant scale height assumtion for unit conversion in climate change simulations.
Results from a systematic analysis of fully coupled Thermo-Hydro-Mechanical-Chemical rock models
Authors: Alvizuri Celso , Podladchikov Yury
Published: March 2020

The rheology/mechanical behavior of rock is controlled by several processes including thermal, hydraulic, mechanical, and chemical conditions. (Braeck et al., 2009; Kiss et al., 2019)

We conduct a systematic parametric study within a fully coupled Thermo-Hydro-Mechanical-Chemical (THMC) numerical rheological model to identify regions of stable and unstable (brittle?) deformation. The rheological model assumes incompressible viscous deformation and is governed by the equations of conservation of mass, linear momentum, and energy; a constitutive equation, and a creep flow law. Three parameters control the deformation: background strain rate, shear heating, and a Brinkman number that captures the interplay between viscosity and temperature.

We setup a grid of points using these parameters, use each grid point as a starting instance of the
rheological model, and let each instance evolve with time. We are able to perform a fine-grained study of the parameter space by using a high-performance GPU cluster. Our initial results show that the background strain rate requires relatively low values (near 1) for the computation to remain stable. While keeping a constant (low) strain rate, we next observe how each model instance evolves with respect to shear heating and Brinkman values. This approach allow us to map stable/unstable regions in the 3-parameter space. 

Next we analyze the rheological conditions of each model instance (in the stable and unstable regions) and its potential as a rock-weakening mechanism.

References
Braeck, S., Podladchikov, Y., & Medvedev, S., 2009. Spontaneous dissipation of elastic energy by self-localizing thermal runaway, Phys. Rev. E , 80, 046105, doi:10.1103/PhysRevE.80.046105.

Kiss, D., Podladchikov, Y., Duretz, T., & Schmalholz, S., 2019. Spontaneous generation of ductile shear zones by thermal softening: Localization criterion, 1D to 3D modelling and application to the lithosphere, Earth Planet. Sci. Lett., 519, 284–296, doi:10.1016/j.epsl.2019.05.026.
Climate change risks to push large parts of global food production and population centres to unprecedented conditions
Authors: Kummu Matti , Heino Matias , Taka Maija , Varis Olli , Viviroli Daniel
Published: March 2020

The majority of global food production, as we know it, is based on agricultural practices developed within stable Holocene climate conditions. Climate change is altering the key conditions for human societies, such as precipitation, temperature and aridity. Their combined impact on altering the conditions in areas where people live and grow food has not yet, however, been systematically quantified on a global scale. Here, we estimate the impacts of two climate change scenarios (RCP 2.6, RCP 8.5) on major population centres and food crop production areas at 5 arc-min scale (~10 km at equator) using Holdridge Life Zones (HLZs), a concept that incorporates all the aforementioned climatic characteristics. We found that if rapid growth of GHG emissions is not halted (RCP 8.5), in year 2070, one fifth of the major food production areas and one fourth of the global population centres would experience climate conditions beyond the ones where food is currently produced, and people are living. Our results thus reinforce the importance of following the RCP 2.6 path, as then only a small fraction of food production (5%) and population centres (6%) would face such unprecedented conditions. Several areas experiencing these unprecedented conditions also have low resilience, such as those within Burkina Faso, Cambodia, Chad, and Guinea-Bissau. In these countries over 75% of food production and population would experience unprecedented climatic conditions under RCP 8.5. These and many other hotspot areas require the most urgent attention to secure sustainable development and equity.
Framework Development for Disaster Risk Dynamics and Resilience Analytics in Complex Socio-Technical Systems
Authors: Huang Tailin , Yu Hwa-Lung , Nikolopoulos Efthymios , Langousis Andreas , Zhu Jin , Dunn Sarah , Yasunobu Maeda
Published: March 2020

In most cases, disasters are assessed at an event-level, for example, by focusing on quantitative surveys of casualties, physical damages, and qualitative root-cause analyses of individual events. The disaster risks are evaluated based on expected utility loss by calculating the probability of occurrence and potential consequences. However, we should know that disaster causes are increasingly sophisticated and usually entangle quickly with deep social and organizational problems, and their impacts are prolonged with a further complication in the nexus of societal systems. To reduce disaster risk, we propose to consider disasters as inseparable parts of the societal operation and critical resource and service circulation, deviating from the well-established concept that a disaster is simply the tragic outcome of human casualties and property damages. Therefore, we will develop a novel DR3 analysis framework to address the dynamic change patterns of risks, i.e., “risk dynamics,” as a key concept for analyzing risk in complex socio-technical systems. In this proposition, DR3 analysis should consider all components of the socio-technical systems that are susceptible to disaster-induced functional perturbations and the DR3 assessment is associated with the overall state change of the socio-technical systems and their performance controllability of the organizations. The failures of the physical systems and individual human factors in the organizations are critical for comprehensive risk analysis. To achieve the goal, we establish a multidisciplinary team to address DR3 vital issues by using the participatory system dynamics modeling approach in this project. Consortium partners will focus on unique disaster cases and test the underlying hypotheses from multiple perspectives. Stakeholders from government agencies and infrastructure service providers will be engaged through continuous and direct involvement in dialogues and activities, supporting the development of risk-dynamics based DR3 solutions.
Ocean surface wave dynamics, energy and momentum air-sea transfer under a variety of wind and waves conditions
Authors: Ocampo-Torres Francisco J. , Osuna Pedro , Rascle Nicolas , Garcia-Nava Hector , Herrera-Vazquez Carlos F. , Pelaez-Zapata Daniel , Robles-Diaz Lucia
Published: March 2020

Direct measurements have been conducted from a spar buoys deployed in the Gulf of Mexico, and in the vicinity of Todos Santos Island, offshore Ensenada BC, Mexico, in order to better understand ocean surface wave modulated processes under a variety of oceanographic and meteorological conditions. Full ocean surface wave directional spectrum is estimated from sea surface elevation data acquired with an array of capacitance wires, to represent directional spectrum as a function of frequency and direction, as well as a function of the wave number components Kx and Ky. Momentum transfer between ocean and the atmosphere is calculated directly through the eddy correlation method applied to wind velocity components acquired with a sonic anemometer. Momentum transfer variability is analysed to study its dependance on the surface wave conditions, with special emphasis on mixed sea states. Comparison between single peak spectra results with those cases where bi-modal spectra were present are performed in order to detect wind stress variability effects. Ocean-atmosphere transfer of momentum is studied and explained in terms of the shape and evolution of the surface wave spectrum. This research is funded by SENER-CONACYT 249795 and 201441 projects.
Morphology, bedload and sedimentology of active gravel bed rivers
Authors: Ashmore Peter
Published: March 2020

Morphology, bedload and sedimentology of morphologically active gravel bed rivers interact in fundamental ways. In braided and wandering rivers these interactions have distinct characteristics.  In these cases much of the bedload transfer is tied up in morphological change so that the bar and channel scale morpho-dynamics are, in effect, the bedload transport process. Physical models and field data reveal several inter-related aspects of this interaction.  We can define the morphological active layer as that in which erosion, deposition and bed particle exchange occur during channel-forming flows. The dimensions, complexity, and lateral and longitudinal connectivity of this layer increase with discharge in a given river and with channel-forming stream power between rivers. Bedload flux correlates strongly with the dimensions of the active layer and temporal variability of bedload at a given discharge is a consequence of bar-scale  variation in morphological change in complex morphology. Rates of planimetric change in braided channels also follow this morphological-bedload relationship. Higher rates of morphological change also correlate with greater bed material mobility, approaching equal mobility at the highest rate of change and the highest morphological active layer dimensions. Bed particle transfer distances and burial depths are also strongly controlled with the length scale and depth of the bar-scale morphology and active layer. The sedimentology reflects the channel morphological scale and processes in defining sedimentary unit thicknesses and geometry. The deposits of the active channel belt are almost homogenous with respect to particle size because of the ‘turnover’ of the bed material.  Morphology, bedload and sedimentology of morphologically active gravel bed rivers interact in fundamental ways that help to define the characteristics of these channel types. To what extent are these observations applicable in other channel types?
COSEISMIQ: First results of high resolution imaging of the shallow crust and relocation of induced seismicity in the Hengill area, Iceland
Authors: Obermann Anne , Sánchez-Pastor Pilar , Duran Alejandro , Diehl Tobias , Hjörleifsdóttir Vala , Wiemer Stefan
Published: March 2020

For the future development of deep geothermal energy exploitation in Europe, large magnitude induced seismic events are an obstacle. On the other hand, the analysis of induced microseismicity allows to obtain the spatial distribution of fractures within the reservoir, which can help, not only to identify active faults that may trigger large induced seismic events, but also to optimize hydraulic stimulation operations and to locate the regions with higher permeability, enhancing energy production. The project COSEISMIQ (COntrol SEISmicity and Manage Induced) integrates seismic monitoring and imaging techniques, geomechanical models and risk analysis methods with the ultimate goal of implementing innovative tools for the management of the risks posed by induced seismicity and demonstrate their usefulness in a commercial scale application in Iceland.

Our demonstration site is the Hengill region in Iceland. The Hengill volcanic complex is located in SW Iceland on the plate boundary between the North American and Eurasian plates. In this region, the two largest geothermal power plants of Iceland are currently in operation, the Nesjavellir (120MW electricity) and the Hellisheidi (300MW electricity) power stations. In October 2018, we densified the permanent seismic network run by ISOR and IMO in this area (14 stations) with 23 broadband seismic stations.

We present the project and show first results from high resolution imaging of the shallow crust with ambient seismic noise, as well as first results from the relocated seismic events. The ambient noise imaging highlights an area of low seismic velocity close to the Þingvallavatn Lake, characteristic for the presence of supercritical fluids. The main geothermal production area is located as well in a low velocity zone that reaches 200 meters depth below Hellisheidi and around 700 meters below Nesjavellir.

 
Reconstructions of Global and Regional Temperature Change for the Last 5 Myr
Authors: Clark Peter U. , Shakun Jeremy , Rosenthal Yair , Bartlein Patrick , Koehler Peter , Mix Hari
Published: March 2020

We use a global array of ~120 sea-surface temperature (SST) records based on Mg/Ca, alkenone, and faunal proxies to reconstruct global and regional temperature change over the last 5 Myr. All records are placed on the LR04 age model. Here we report the reconstructions and discuss their implications for characterizing global climate evolution (frequency, variance, transitions) over this interval and its relationship to changes in CO2, orbital forcing, and mean ocean temperature. Average global temperature has cooled by ~6.5oC since 5 Ma, with significant breakpoints tentatively identified at ~3.38 Ma, 1.34 Ma, and 0.88 Ma. We also invert the global reconstruction to reconstruct global sea level for the last 5 Myr.
Analysis of the level of urban residential land based on land cover/land use
Authors: fengguang kang
Published: March 2020

The level of urban residential land has a great relationship with the composition of urban residential land and the urban residential area of human settlements. Urban residential land includes residential land, road land, ancillary facilities and public green land. Geographical information monitoring land cover/land use includes cultivated land, garden land, forest land, grassland, housing construction area, roads, structures, artificial digging land, desert and bare land, and water. The Land cover/land use data and resident population spatialization data based on maps of housing construction areas are this article’s data sources. This article chose urban residential land types and per capita residential land area as an evaluation index system, establish the relationship between residential land indicators and geographical information monitoring indicators, calculate the area of various residential land areas and per capita land area, and follow the "Urban Residential Area Planning and Design Standards", a statistical analysis of the land use of residents in the five-, ten-, and fifteen-minute living quarters. Select a test area from each of the megacities, megacities, large cities, medium cities, and small cities, and use the statistical results to determine the level of urban residential land Perform a comparative evaluation.
Time dependence of climate sensitivity
Authors: Eiselt Kai-Uwe , Graversen Rune , Fredriksen Hege-Beate
Published: March 2020

Climate sensitivity is a measure for the global mean temperature change of the earth in response to a given radiative forcing. In an experiment with an instantaneous forcing by e.g. a doubling of the atmospheric CO2 content the radiative imbalance at the top of the atmosphere can be regarded as a function of the global mean temperature change. In such an experiment the climate sensitivity can be approximated by linearly extrapolating to zero the TOA imbalance where equilibrium is obtained. The thus derived value is usually referred to as effective climate sensitivity. It has been established however, that the effective climate sensitivity changes over time. While the reason for this change is not clear, most recent investigations of the abrupt4xCO2 experiments of multiple members of the CMIP5 archive point to a delay in warming of the eastern tropical Pacific region relative to the global average in the multi model mean. Due to high stability in this region the heat is trapped there close to the surface which reduces the local lower tropospheric stability. The trapping of the warming close to the surface implies that the longwave cooling is less efficient in this region and its delayed warming relative to the global average increases global climate sensitivity over time. The decrease in lower tropospheric stability furthermore reduces low cloud cover leading to less negative low cloud feedback which causes additional warming.

We investigate the delayed warming in the eastern Pacific region in more detail in terms of its effects on stability as well as clouds for individual members and multi model means of both the CMIP5 and CMIP6 archives. We find that in the multi model mean, the CMIP6 members show an even larger delayed warming than the CMIP5 members. Furthermore, the individual members of both archives generally exhibit the same pattern of delayed eastern tropical Pacific warming and a corresponding decrease in lower tropospheric stability in the same region, which indicates robustness of the earlier results based on the CMIP5 multi model mean. Additionally, there is a decrease in liquid water content in the lower atmospheric layers, confirming the influence of reduced lower tropospheric stability on low clouds. However, there are several further regions such as the Southern Ocean with a consistent delayed warming and reduced stability, which might influence climate sensitivity as well.
Assessment of groundwater resource vulnerability to over-exploitation in a tropical, agricultural basin
Authors: Batelaan Okke , Partington Daniel , Vu Manh Hai , Shanafield Margaret
Published: March 2020

In many parts of the world, groundwater extraction for agriculture is strongly increasing, causing severe stress on groundwater resources and associated ecosystems. Understanding how groundwater flow systems support extractions is therefore essential. However, particularly in developing, rural, tropical regions, monitoring of groundwater levels, chemistry and extractions is poorly regulated, resulting in a lack of data. Hence, alternative approaches are necessary to develop best management practices in these groundwater basins. In this study, catchment-scale groundwater extraction is indirectly estimated by two “soft data” approaches: (1) using local knowledge through a qualitative field survey of groundwater level fluctuations and groundwater withdrawals; and (2) land-use/population data combined with local knowledge on cropping/water use practices. Spatially distributed recharge is simulated on the basis of a monthly water balance model, which requires widely available topographic, soil, land-use and meteorological data. Extractions and recharge force a simple, basin-scale groundwater model for assessment of impact of irrigation practices. Agricultural scenarios are developed and modelling procedures are designed to test the temporal and spatial vulnerability over a 100 yr time span of the groundwater resource. The approaches are tested and applied for the agricultural La Vi River basin, Vietnam, where the livelihood of the local farmers requires development of new agricultural and hydrological techniques. The typical cash-crops are cultivated on sandy soils and irrigated in the dry season from thousands of private shallow wells. The tropical climate and strong seasonal rainfall pattern produces a strong fluctuation in groundwater levels. The modelling shows significant spatio-temporal unmet pumping demand dependent on the agricultural development scenario, indicating the need and opportunity for planning of groundwater based irrigation development. Overall, the multi-method comprehensive approach supports basin-scale sustainable groundwater resource development and only requires relatively easily accessible data.
A systematic synthesis of agricultural management impacts on crop yield, soil quality, and environment
Authors: Young Madaline , de Vries Wim , Ros Gerard H.
Published: March 2020

Management practices aiming to improve crop yields may have adverse effects on soil or environmental quality, whereas the reverse can also be true. There is a need for a better understanding of synergies and trade-offs of nutrient, crop and soil management impacts on agronomic and environmental indicators , taking into account a variety of regional agro-ecosystem properties.

Well-known key indicators in this context are crop yield, nutrient uptake and use efficiency, soil organic carbon (SOC) and nutrient content, soil compaction, GHG emissions, and nutrient surpluses. Meta-analysis is a valuable way to assess the magnitude of agricultural management impacts over multiple sites and years, assessing the overall effect from many empirical observations. As many meta-studies exist in the literature to quantify the effects of agricultural management practices, we are the first presenting an integrated overview of those published studies on the above-mentioned impacts simultaneously. We focused on management principles for sustainability, including crop rotation and residue incorporation, irrigation, tillage, the “4R” principles of right fertilizer source, rate, timing, and placement, as well as enhanced efficiency and biochar amendments.

We find that various management-impact relationships are covered by meta-studies, but there is a lack of holistic analysis of site properties (and their interactions), which control the effects of management measures. Since current meta-studies allow limited conclusions on the effects of specific soil and climate agro-ecosystem properties, better analyses of site-specific conditions are needed.

When multiple meta-studies report effect sizes for the same management impact and given indicators, we further synthesized the results by a weighted mean based on reported measures of variation. Our synthesis produced almost 2000 impact assessments of agronomic measures from meta-analysis papers, providing a valuable quantitative resource for scientists and stakeholders in agriculture. For example, when comparing best management practices relating to fertilizer source, tillage, and crop rotation, our results indicate combined fertilizer as most effective in reducing N surplus, organic fertilizer as most effective in increasing SOC, and no tillage as most effective in increasing yields.

Our review also focuses on key characteristics relating to quality and methodological approaches in meta-analysis. For example, a surprising number of meta-studies do not perform a weighted analysis, which we consider an important quality standard. In general, our insights are relevant for the state of meta-analysis in agricultural science, which can be considered a recently developed focus of research.
Study on Urban Thermal Environment based on Diurnal Temperature Range
Authors: Guo Zheng , Cheng Miaomiao
Published: March 2020

Diurnal temperature range (includes land surface temperature diurnal range and near surface air temperature diurnal range) is an important meteorological parameter, which is a very important factor in the field of the urban thermal environmental. Nowadays, the research of urban thermal environment mainly focused on surface heat island and canopy heat island.

Based on analysis of the current status of city thermal environment. Firstly, a method was proposed to obtain near surface air temperature diurnal range in this study, difference of land surface temperature between day and night were introduced into the improved temperature vegetation index feature space based on remote sensing data. Secondly, compared with the district administrative division, we analyzed the spatial and temporal distribution characteristics of the diurnal range of land surface temperature and near surface air temperature.

The conclusions of this study are as follows:

1 During 2003-2012s, the land surface temperature and near surface air temperature diurnal range of Beijing were fluctuating upward. The rising trend of the near surface air temperature diurnal range was more significant than land surface temperature diurnal range. In addition, the rise and decline of land surface temperature and near surface air temperature diurnal range in different districts were different. In the six city districts, the land surface temperature and near surface air temperature diurnal range in the six areas of the city were mainly downward. The decline trend of near surface air temperature diurnal range was more significant than land surface temperature diurnal range.

2 During 2003-2012s, the land surface temperature and near surface air temperature diurnal range of Beijing with similar characteristics in spatial distribution, with higher distribution land surface temperature and near surface air temperature diurnal range in urban area and with lower distribution of land surface temperature and near surface air temperature diurnal range in the Northwest Mountainous area and the area of Miyun reservoir.