bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating Modelled Aerosol Absorption by Simulating the UV Aerosol Index using Machine Learning
Authors: Sun Jiyunting , Veefkind J.Pepijn , van Velthoven Peter , Levelt Pieternel.F
Published: March 2020

The environmental effects of absorbing aerosols are complex: they warm the surface and the atmosphere on a large scale, while locally they cool the surface. Absorbing aerosols also affect precipitation and cloud formation. A comprehensive understanding of aerosol absorption is important to reduce the uncertainties in aerosol radiative forcing assessments. The ultraviolet aerosol index (UVAI) is a qualitative measure of aerosol absorption provided by multiple satellite missions since 1978. UVAI is directly calculated by the difference between the measured spectral contrast and the simulated ones in the near-UV channel, without assumptions on aerosol properties. This long-term global daily data set is advantageous for many applications. In previous work, we have attempted to derive the single scattering albedo (SSA) from UVAI. In this work, we evaluate the UVAI derived from a chemistry transport model (CTM) with satellite observations. Conventionally, UVAI from a model aerosol fields at a satellite footprint is simulated using a radiative transfer model. In order to do this, one has to make assumptions on the spectral dependence of the aerosol optical properties. The lack of measurements and our poor knowledge of these properties may lead to large uncertainties in the simulated UVAI, and these uncertainties are difficult to quantify. In this work, we propose an alternative method, that is to simulate the UVAI based on Machine Learning (ML) approaches. A training data set is constructed by independent measurements and/or model simulations with strict quality controls. We simulate the UVAI using modelled aerosol properties, the Sun-satellite geometry and the surface parameters. The discrepancy between the retrieved UVAI and the ML predictions can help us to identify the unrealistic inputs of aerosol absorption in the model.
Seasonal prediction of the austral summer Southern Annular Mode, and investigation of its connection to the Southern Ocean
Authors: Hempel Tim , Düsterhus André , Baehr Johanna
Published: March 2020

The Southern Annular Mode (SAM) modulates the eddy-driven-westerly jet in the southern mid- to high-latitudes. This modulation has major impacts on the seasonal climate in the southern hemisphere. Thus, a seasonal prediction of the SAM is desirable. Still, only few studies show a significant prediction skill on this timescale. In this contribution the prediction skill of the SAM is improved by using its physical links to the Southern Ocean.

We use the seasonal prediction system based on the Max-Planck-Institute Earth-System-Model (MPI-ESM) in mixed resolution (MR). In ensemble reforecasts for 1982 to 2016 we find large regions of the surface ocean in the southern mid- to high-latitudes to be significantly predictable on seasonal timescales. In contrast, the atmospheric variables in the same regions show only very little skill. In the austral summer season (December-January-February (DJF)) different ensemble members evolve considerably different in the ocean and the atmosphere. With physical links between the Southern Ocean and the SAM, identified in ERA-Interim, we only select ensemble members that also show these links. This process is repeated every year and leads to a new time series with a reduced number of ensemble members. To evaluate the prediction skill of the new ensemble mean SAM we use the correlation coefficient and the Heidke Skill Score (HSS). The reduced ensemble has a correlation with ERA of 0.50, while the full ensemble shows a correlation of 0.31. Similarly the reduced ensemble has a HSS of 0.35 compared to the HSS of the full ensemble of 0.17.

We additionally show that choosing the same ensemble members we selected for the SAM also increases the prediction skill for other atmospheric variables. The reduced ensemble has an increased prediction skill for pressure, wind, and temperature in the southern mid- to high-latitudes, to which the selection is targeted.
Effect of particle size on indicator gas emission during high-temperature oxidation of weathered coal
Authors: Song JiaJia , Deng Jun , Zhao JingYu
Published: March 2020

Coal spontaneous combustion is one of the severe nature hazards among nature resources. There are many influence factors which control the development of spontaneous combustion such as particle size, oxygen concentration, etc. Weathering effects alter the spontaneous combustion characteristics of coal. To explore the effect of particle size on gas emission from weathered coal under high temperature oxygen deficiency, the macroscopic spontaneous combustion characteristics of weathered coal with various particle sizes in high temperature oxidation process were studied. The gas concentration of different particle sizes with weathered coal oxidation from normal temperature to 600 °C was tested by the self-built high temperature program experiment system, and the variation law of the indicator gas was analyzed. The results showed that there were different experimental phenomena in each particle size coal sample. The concentration of indicator gas neither increased nor decreased monotonically with the change of particle size. Roughly, 3 mm is the critical particle size in the process of high temperature oxidation of weathered coal. The experimental results provided a pivotal theoretical basis for the early prediction and the scientific prevention of the spontaneous combustion of the weathered coal during the mining process of the open pit and the shallow coal seam.
Preferential flow induced nutrient gradients create microbial hotspots and shape bacterial community structure
Authors: Franklin Shane , Jin Yan , Vasilas Bruce
Published: March 2020

In this study we used oxygen sensitive optodes, or optical sensor devices, to observe oxygen depletion by soil microbes. Depletion served as a reference for microbial activity along three artificially constructed preferential flow paths consisting of coarse sand in the center surrounded fine sand. Following a flow event with glucose addition, images showed that oxygen depletion is greatest along the boundary between preferential flow paths (coarse sand) and the bulk matrix (fine sand). Oxygen gradients as well as nutrient gradients are commonly attributed to shaping soil bacterial communities, however, these mechanisms have not been studied in the specific soil architecture of preferential flow paths. A separate experiment was performed in which the fine sand matrix was replaced with a sandy soil containing its native microbial community. An addition of glucose and DOM was flowed through the columns containing real soil. Oxygen depletion was again monitored using oxygen sensor foils. To assess changes in the microbial community in time 16S rRNA analysis was performed on soil samples taken from different locations within the chambers. By monitoring the levels of oxygen depletion in time, we are able to gain an understanding of how this dynamic process alters microbial community structure. Additionally, zymography was performed to elucidate the locations where enzyme activity was greatest. By studying the microbial community in time along with oxygen depletion and enzyme activity, we are able to gain insight into structure-function relationships that take place within preferential flow paths. Furthering our understanding of processes taking place within preferential flow paths will allow for better estimation of how these entities function biogeochemically.
Cold Atom Interferometer activities for measuring the Earth’s gravity field
Authors: Massotti Luca , Carraz Olivier , Bensi Paolo , Haagmans Roger , Martimort Philippe , Silvestrin Pierluigi
Published: March 2020

In the past decade, it has been shown that atomic quantum sensors are a newly emerging technology that can be used for measuring the Earth’s gravity field. Whereas classical accelerometers, based e.g. on capacitive sensing and electrostatic actuation, are limited by relatively high noise at low frequencies, Cold Atom Interferometers (CAI) can be highly accurate over the entire frequency range, which also has the benefit that they do not need any calibration phase. Several studies related to these new sensor concepts were initiated at ESA, mainly focusing on technology development for different instrument configurations (gravity gradiometers and  satellite-to-satellite ranging systems) and including validation activities, e.g. two successful airborne surveys with a CAI gravimeter. We will present the first conclusions of these different mission and instrument studies:

The first airborne gravity survey during the ESA Cryovex/KAREN 2017 campaign using this technology was conducted by DTU and ONERA. The measurements did not show any drift and the accuracy was found to be less than 4 mGal at 11 km resolution. A second campaign has been conducted by ONERA and CNES in 2019 in the South of France and improved the accuracy by a factor 4, reaching classical airborne survey state-of the art performance.

A first space quantum gravity mission concept is based on a gravity gradiometer that delivers a very high common mode rejection, greatly relaxing the drag-compensation requirements.

The second concept is based on quantum accelerometers for correcting low frequency errors of electrostatic accelerometers that are used in a low-low satellite-to-satellite ranging concept in order to measure non-gravitational accelerations.

For both concepts we will present the expected improvement in measurement accuracy and in the derived Earth gravity field models, taking into account the different types of measurement (e.g. single axis vs. three axis, integration time, etc.) and different mission parameters (e.g. attitude control, altitude of the satellite, lifetime of the mission, etc.). A technology roadmap will be outlined for potential implementation of a quantum inertial sensor geodesy mission within 10-15 years.
The Airyx 2D SkySpec instrument: MAX-DOAS measurements of tropospheric NO2 and HCHO in Munich and the comparison to satellite observations
Authors: Lampel Johannes , Chan Ka Lok , Pöhler Denis , Wiegner Matthias , Alberti Carlos , Platt Ulrich , Wenig Mark
Published: March 2020

We present the Airyx 2D SkySpec Instrument: A commercially available two-dimensionally scanning Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) setup for the observations of trace gases using spectral measurements of scattered sun light and optionally also direct sun light. The waterproof design of the scanner unit is designed for long-term outdoor deployment. Temperature stabilisation of the spectrometers and automatic calibration spectra measurement are used to ensure high-quality measurement data over months and years of observations.

We show 2.5 years of measurements in Munich. Vertical columns and vertical distribution profiles of aerosol extinction coefficient, NO2 and HCHO are retrieved from the 2D MAX-DOAS observations. The measured surface aerosol extinction coefficients and NO2 mixing ratios are compared to in-situ monitor data. The retrieved surface NO2 mixing ratios show good agreement with in-situ monitor data with a Pearson correlation coefficient (R) of 0.91. Good agreement (R= 0.80) is also found for AOD when compared to sun-photometer measurements. Tropospheric vertical column densities (VCDs) of NO2 and HCHO derived from the MAX-DOAS measurements are also used to validate OMI and TROPOMI satellite observations. Monthly averaged data show good correlation, however, satellite observations are on average 30% lower than the MAX-DOAS measurements. Furthermore, the 2D MAX-DOAS observations are used to investigate the spatio-temporal characteristic of NO2 and HCHO in Munich. Analysis of the relations among aerosol, NO2 and HCHO show higher aerosol to HCHO ratios in winter indicating a longer atmospheric lifetime of aerosol and HCHO. The analysis also suggests that secondary aerosol formation is the major source of aerosols in Munich.
A catchment to coast framework for the evolution of a coastal mangove wetland
Authors: Rodriguez Jose , Jorquera Eliana , Saco Patricia , Breda Angelo
Published: March 2020

Coastal wetlands are at the interface between land and sea, receiving water, sediment and nutrients from upstream catchments and also being subject to tides, wave and changing sea levels. Analysis of their future evolution requires the analysis of the entire catchment to coast system, including the effects of climate variability and change and land use changes. We have developed a modelling framework that is able to include both catchment and coastal processes into the evolution of coastal wetlands by coupling an ecogeomorphological wetland evolution model with a hydrosedimentological catchment model to include both tidal and catchment runoff inputs. We drive the model with storm events and sea-level variations and analyse scenarios of future climate and land use for a catchment in Vanua Levu, Fiji that includes a mangrove wetland at the catchment outlet. We inform our model with field, remote sensing and historical data on land use, tides, sediment and nutrient transport and cyclone activity.
How many grains do we need for tracer thermochronology?
Authors: Madella Andrea , Glotzbach Christoph , Ehlers Todd A.
Published: March 2020

Detrital tracer thermochronology exploits the relationship between bedrock cooling age and elevation, whereby detrital cooling age distributions can inform the pattern of erosion in the upstream area. Typically bedrock ages exhibit a positive relation with elevation, since the exhumation path from the closure isotherm to the surface is longer. Therefore, spatially uniform erosion should yield a detrital cooling age distribution that mirrors the catchment’s hypsometric curve, corrected for mineral fertility. Applying thermochronometers is time consuming and expensive, hence measured detrital age populations have a limited sample size (rarely exceeding 100 grains) and only provide an approximation of the natural continuous detrital age distribution. With such limited sample sizes, discerning between two detrital age distributions resulting from different erosional patterns may be statistically impossible at a high confidence level.

Here, we investigate the impact of sample size on the detrital cooling age distributions and the resulting uncertainty in addressing the erosional pattern of the upstream area. To do so, we forward model a continuous detrital age distribution as a function given parameters, such as catchment hypsometry, mineral fertility, exhumation rate, analytical uncertainty and erosion scenario. A random subsample of the entire detrital population is drawn for each possible sample size, from which an approximate cumulative distribution function (CDF) is calculated. Then we compute the divergence of the approximate CDF from the reference continuous CDF as well as from the continuous CDF obtained for a different erosion scenario. The confidence level at which an approximate CDF can be tied to a specific erosion scenario is iteratively estimated for each sample size. We carry out the outlined approach for a synthetic catchment with elevations ranging between 0.5-2.2 km, where bedrock cooling ages increase by 30 My/km and prescribing a 10% standard deviation for single grain ages.

We find that, if the location of the erosion maximum coincides with the peak of the hypsometric curve, 100 grains do not suffice to resolve a local tenfold increase in erosion at the 95% confidence level. In this worst case scenario 240 grains would be required. However, for the same case, 70 grains are enough at the 68% confidence level. This study provides a method to consistently quantify the uncertainty of detrital tracer thermochronology as a function of sample size, case-specific variables and the initial scientific question.
A small-scale numerical study of fault slip mechanisms using DEM
Authors: Casas Nathalie , Mollon Guilhem , Daouadji Ali
Published: March 2020

How do earthquakes start? What are the parameters influencing fault evolutions? What are the local parameters controlling the seismic or aseismic character of slip?

To predict the dynamic behaviour of faults, it is important to understand slip mechanisms and their source. Lab or in-situ experiments can be very helpful, but tribological experience has shown that it is complicated to install local sensors inside a mechanical contact, and that they could disturb the behaviour of the sheared medium. Even with technical improvements on lab tools, some interesting data regarding gouge kinematics and rheology remains very difficult or impossible to obtain. Numerical modelling seems to be another way of understanding physics of earthquakes.

Fault zone usually present a granular gouge, coming from the wear material of previous slips. That is why, in this study, we present a numerical model to observe the evolution and behaviours of fault gouges. We chose to focus on physics of contacts inside a granular gouge at a millimetre-scale, studying contact interactions and friction coefficient between the different bodies. In order to get access to this kind of information, we implement a 2D granular fault gouge with Discrete Element Modelling in the software MELODY (Mollon, 2016). The gouge model involves two rough surfaces representing the rock walls separated by the granular gouge.

One of the interests of this code is its ability to represent realistic non-circular grain shapes with a Fourier-Voronoï method (Mollon et al., 2012). As most of the simulations reported in the literature use circular (2D)/spherical (3D) grains, we wanted to analyse numerically the contribution of angular grains. We confirm that they lead to higher friction coefficients and different global behaviours (Mair et al., 2002), (Guo et al., 2004).

In a first model, we investigate dry contacts to spotlight the influence of inter-particular cohesion and small particles on slip behaviour and static friction. A second model is carried out to observe aseismic and seismic slips occurring within the gouge. As stability depends on the interplay between the peak of static friction and the stiffness of the surrounding medium, the model includes the stiffness of the loading apparatus on the rock walls.

The work presented here focuses on millimetre-scale phenomena, but the employed model cannot be extended to the scale of the entire fault network, for computational cost reasons. It is expected, however, that it will lead to a better understanding of local behaviours that may be injected as simplified interface laws in larger-scale simulations.
3D high order seismic imaging in Gulf of Mexico in the context of RTM algorithm using adjoint-based methods.
Authors: Abreu Javier , Martin Roland , Darrozes Jose
Published: March 2020

The present work consists in imaging salt bodies from earth subsoil in the context of Reverse Time Migration (RTM) algorithm. The study of salt domes is economically important because they form a natural trap for hydrocarbons. For instance, more than a half of the hydrocarbon reserves that still exist today are related to salt bodies.

However, seismic images coming from strong salt tectonics area, are contaminated with spurious signal, like multiple events. Therefore, it is important to know how to treat and filter multiples in order to have seismic images that are geologically interpretable.

For this purpose, we solved the forward 3D elastic seismic wave equations using high order finite differences. The earth parameters come from 3D velocity and density models in a salt tectonic region in the North Gulf of Mexico. To obtain the imaging condition we compute the sensitivity kernels by using the adjoint solution of wave equation and by applying checkpointing. We tested this algorithm with simultaneous and separated sources. Fluid - solid interfaces at the ocean bottom is introduced, interfaces are well retrieved at large offsets.

Furthermore, we applied CPML absorbing boundaries, and replace also free surface conditions for absorbing boundaries to attenuate free surface multiples. The images we obtained from sensitivity kernels are easily interpretable. The calculations were performed on CALMIP supercomputing platforms in Toulouse France. 
Investigating the impact of different drought-heat signatures on carbon dynamics using a dynamic global vegetation model
Authors: Tschumi Elisabeth , Lienert Sebastian , van der Wiel Karin , Joos Fortunat , Zscheischler Jakob
Published: March 2020

Droughts and heat waves have large impacts on the terrestrial carbon cycle. They lead to reductions in gross and net carbon uptake or anomalous increases in carbon emissions to the atmosphere because of responses such as stomatal closure, hydraulic failure and vegetation mortality. The impacts are particularly strong when drought and heat occur at the same time. Climate model simulations diverge in their occurrence frequency of compound hot and dry events, and it is unclear how these differences affect carbon dynamics. Furthermore, it is unknown whether an increase in frequency of droughts and heat waves leads to long-term changes in carbon dynamics, and how such an increase might affect vegetation composition.

To study the immediate and long-term effects of varying signatures of droughts and heat waves on carbon dynamics such as inter-annual variability of carbon fluxes and cumulative carbon uptake, we employ the state-of-the-art dynamic global vegetation model LPX-Bern (v1.4) under different drought-heat scenarios.

We have constructed five 100-yr long scenarios with different drought-heat signatures, representing a “control”, “close to mean seasonal cycle”, “drought only”, “heat only”, and “compound drought and heat” climate forcing to LPX-Bern. This is done by sampling daily climate variables from a 2000-year stationary simulation of a General Circulation Model (EC-Earth) for present-day climate conditions. Such a sampling ensures physically-consistent co-variability between climate variables in the climate forcing.

We investigate the carbon-cycle response and changes in vegetation structure to different drought-heat signatures on a global grid, representing different land cover types and climate zones. Our results provide a better understanding of the links between hot and dry conditions and carbon dynamics. This may help to reduce uncertainties in carbon cycle projections, which is important for constraining carbon cycle-climate feedbacks.
Volatile Organic Compound fluxes in a subarctic peatland and lake
Authors: Seco Roger , Holst Thomas , Westergaard-Nielsen Andreas , Li Tao , Simin Tihomir , Jansen Joachim , Crill Patrick , Friborg Thomas , Holst Jutta , Rinne Janne , Rinnan Riikka
Published: March 2020

Arctic climate is warming twice as much as the global average, due to a number of climate system feedbacks, including albedo change due to retreating snow cover and sea ice, and the forest cover expansion across the open tundra. Northern ecosystems are known to emit trace gases (e.g., methane and volatile organic compounds, VOCs) to the atmosphere, from sources as diverse as soils, vegetation and lakes. These trace gas fluxes are likely to show a trend towards greater emissions with climate warming.

Here we report ecosystem-level VOC fluxes from Stordalen Mire, a subarctic peatland complex with a high fraction of open pond and lake surfaces, underlain by discontinuous permafrost and located in the Subarctic Sweden (68º20' N, 19º03' E).

In 2018, we deployed two online mass spectrometers (PTR-TOF-MS) to measure rapid fluctuations in VOC mixing ratios and to quantify ecosystem-level fluxes with the eddy covariance technique. One of the instruments obtained a growing-season-long dataset of biogenic emissions from palsa mire vegetation dominated by mosses (e.g., Sphagnum spp.), graminoids (such as Eriophorum spp. and Carex spp.), dwarf shrubs (e.g. Empetrum spp. and Betula nana) surrounding the ICOS Sweden Abisko-Stordalen long-term measurement station. The second instrument measured VOC fluxes during two contrasting periods (the peak and the end of the growing season) from a subarctic lake and its adjacent fen, permafrost-free, minerotrophic wetland with vegetation dominated by tall graminoids, mainly Carex rostrata and Eriophorum angustifolium.

At both sites, isoprene was the dominant VOC emitted by vegetation, showing clear diurnal patterns along the season and especially during the peak of the growing season in July. At the ICOS Sweden station, isoprene fluxes exceeded 2 nmol m-2 s-1 on several days in July, with a July monthly average midday emission of 1 nmol m-2 s-1. The fen site showed average midday emissions of 2 nmol m-2 s-1 during the peak growing season. Other VOCs emitted by vegetation at both sites in July were, with decreasing magnitude, methanol, acetone, acetaldehyde and monoterpenes. In contrast, acetaldehyde and acetone were not emitted but mostly deposited to the fen at the end of the season. In contrast to the wetland, the lake was a sink for acetaldehyde and acetone during all measurement periods.

Thermal imaging and spectral analysis of vegetation will be used to assess relationships between VOC fluxes, vegetation surface temperatures and phenology under varying environmental conditions.
Eddy covariance and CRDS based techniques of GHGs measurements provide additional constraint in partitioning the net ecosystem exchange
Authors: Chakraborty Supriyo , Metya Abirlal , Datye Amey , K. Deb Burman Pramit , Sarma Dipankar , Gogoi Nirmali , Bora Abhijit
Published: March 2020

Greenhouse gases such as CO2 and CH4 are emitted by various sources. Among the natural ecosystems, forests and wetlands are believed to emit sizeable amount of these gases by means of autotrophic, heterotrophic respirations and bacterial activities. Additionally, a relatively new source has been detected; the emission of CH4 by trees and plants. A growing evidence suggests that a significant amount of CH4 is generated especially by the trees in forested ecosystems. Eddy-covariance (EC) based technique is widely used to estimate the GHGs and energy fluxes in natural ecosystems. The net ecosystem exchange (NEE), measured by an EC system, typically represents the net CO2 fluxes arising due to the biosphere's photosynthetic and respirative processes. The net flux derived by this system, is subsequently partitioned into two components, the respired carbon and the assimilated carbon. However, the partitioning processes may have their own shortcomings which introduce significant errors. To reduce the uncertainty, the NEE needs to be constrained by some additional measurement. We have used a real time GHG analyzer in association with an existing EC system in a tropical forest of north-east India, the Kaziranga National Park, to better constrain the above two carbon fluxes. The GHG analyzer provided CO2 and CH4 concentrations as well as their carbon isotopic ratios. The isotopic data were used to partition the EC derived NEE records, which showed a good agreement with the EC measurements within the limits of experimental uncertainty. However, long-term observation is required to establish the potential of this relatively new method in this endeavour. Additionally, the isotopic data provided a strong evidence of plant generated CH4 , which was apparently not possible to identify by the conventional means. This work will present the three years (2016-2018) of NEE data to demonstrate the unique characteristics of the carbon transfer processes of one of the major forested regions of north-east India, with a special reference to its partitioning by means of the isotopic analysis carried out on a campaign mode observation in Feb 2019.
Land use changes at the former “Iron curtain” and their implications for catchment hydrology, erosion and ecology – a transboundary project between Austria and Czech Republic
Authors: Höfler Sarah , Ringler Gerald , Gumpinger Clemens , Hauer Christoph
Published: March 2020

The river Maltsch / Malše is an interesting waterbody from a historical, hydrological and ecological perspective. As a border river between Austria and the Czech Republic, it has had an eventful history. With the political separation into “East” and “West” in the middle of the 20th century, a region that initially had a similar land use structure was completely changed. On the Czech side, villages and settlements were removed and the land expropriated. In the course of the fall of the Iron Curtain, the land was mostly sold to large landowners. Changes also took place on the Austrian side. Agriculture and forestry have been intensified over decades.

This leads to the situation that on both sides of the river, under very similar geological and hydrological conditions, the effects of very different land use developments and changes on the water household and erosion can be documented. Thus, a transboundary, mainly EU-funded INTERREG project was launched to investigate this variability in general and to address the implications for the sediment regime in such river systems (concerning e.g. flood protection control, sedimentation of reservoirs) in specific. Moreover, it is examined how mitigation measures for water retention, erosion control and climate change adaption can be planned under these variable boundary conditions. Especially droughts and heavy rainfall events must be considered as threats in the region in the future.

In addition to the changes described above, the political situation in the border region has left a refuge for nature. The Maltsch is part of the so-called Green Belt that stretches across the whole of Europe. A key species of the region is the Freshwater Pearl Mussel (Margaritifera margaritifera), which is characterised by its very high demands on the environment. It, therefore, serves very well as an indicator / umbrella species and thus also as a condensation nucleus of the different topics of the project.

In summary, the following aspects will be presented: (1) documentation of historic, political driven land use changes and land use differences on GIS basis, (2) effects on soil erosion by means of modelling via USLE, (3) estimation of the effects on the landscape hydrology and (4) effects on the aquatic fauna, especially the key species Freshwater Pearl Mussel.
2000 years of marine primary productivity in the Eastern Tropical North Pacific
Authors: Treinen-Crespo Christina , Carriquiry Jose , Villaescusa Julio , Repiso-Terrones Elisabet
Published: March 2020

Changes in marine primary productivity (MPP) over the 21st century are expected to occur under the prevailing climate change scenario. For better understanding of past climate variability, we reconstructed MPP at high resolution (~1-2 years) for the past 2000 years analyzing biogenic silica and total organic carbon (TOC %) on a sediment core collected from Soledad Basin (25°N, 112°W), Baja  California, Mexico. Located in the Eastern Tropical North Pacific, this suboxic basin is ideal for palaeoceanographic reconstructions due to its high sedimentation rate (2 mm/year), which allow us to reconstruct past changes in the ocean and climate at high resolution. Our results show an increasing trend in the variability of MPP for the past 2000 years: biogenic silica content does not show a well-defined trend, but rather it is dominated by strong multidecadal and prominent centennial-scale cycles while TOC (%) shows a slight increasing trend towards the present, starting at least 2000 years ago. Spectral analysis confirms the presence of multidecadal to centennial cycles. These results will be discussed in the context of the Anthropocene and natural climate variability.
Uncertainty analysis of the global hydrological model WGHM using the GLUE method for multi-type variables in the Mississippi basin
Authors: shadkam somayeh , Hasan Mehedi , Niemann Christoph , Guenter Andreas , Döll Petra
Published: March 2020

In this research we evaluated the WaterGAP Global Hydrological Model (WGHM) parameter uncertainties and predictive intervals for multi-type variables, including streamflow, total water storage anomaly (TWSA) and snow cover based on the Generalized Likelihood Uncertainty Estimation (GLUE) method, for a large river basin in North America, the Mississippi basin. The GLUE approach is built on Monte Carlo concept, in which simulations are performed for all the parameter sets. The parameter sets are sampled from a prior range of the parameters using the Latin Hypercube Sampling. The Nash-Sutcliffe efficiency was used as likelihood measure in case of all variables. The behavioral set of models were selected as those which result likelihood measures above the pre-specified thresholds for all three variables or subsets. These behavioral parameters set were used to analyze different parameters uncertainties, trade-offs among the variables, and the influence of each individual observation data on constraining other variables.
Residents' awareness of Sustainable Development Goals (SDGs) after Grain to Green Project implementation in Loess Plateau
Authors: zhou ao , Zhao Wenwu
Published: March 2020

Since GTGP (Grain to Green Project) has implemented in 1999, soil erosion and vulnerable habitat have substantially improved along with the enhancement of human living standards. Under vision of Sustainable Development Goals (SDGs), how residents evaluate sustainable development status plays important role in regulating objectives of the policy. Yet, few researches involved. In this study, we conducted interview survey to investigate the subjective viewpoints on SDG and ES. Overall, we collected 667 valid questionnaires from 13 counties (districts) in Yan’an city. Results indicated that environmental quality has been improved, which included improvement of water quality, amelioration of soil erosion, increase of vegetation types and spiritual acquirement, as well as maintenances of species diversity habitat quality. As for living standard, although respondents’ a grain output decreased, the income not decreased because of ecological compensation. Besides, farmers can increase their income by engaging in the tertiary industry. With regards to SDG awareness, there are trade-off between protecting biodiversity (SDG 15) and economic growth (SDG 8). In addition, farmers' awareness of environmental protection and social responsibility have been significantly strengthened. We conclude that, although perceptions of ES have showed a significant improvement, there are still gaps hindering achievement of regional SDGs, which reflected by lacking collective identification on economic and environment aspects.
On the relationship between the vertical distribution-migration of zooplankton and the organic carbon flux, before, during and after convective events, in the open southern Adriatic Sea
Authors: Batistić Mirna , Garić Rade , Miserocchi Stefano , Langone Leonardo , Ursella Laura , Cardin Vanessa
Published: March 2020

The Southern Adriatic (SA) is the deepest part of the Adriatic Sea (1242 m) and one of three sites of open-sea deep convection in the Mediterranean. Due to winter convection events, the dense water formation processes in the open SA result in a homogenization of the water column, which determines the nutrient input into the euphotic zone, enhances phytoplankton growth and consequently, the abundance of zooplankton.

By analyzing zooplankton samples, together with acoustic data (ADCP) and data from sediment traps (at 125 m and 1150 m) taken in the SA from November 2015 to June 2016, we investigated the relationship between the distribution of zooplankton abundance and the flow of organic carbon in the deep open southern Adriatic Sea. During the pre-convection period (November 2015), the highest organic carbon flux (C org flux) was found at both depth (125 m, 1150 m), which is probably related to the autumn phytoplankton bloom and consequently an increase in zooplankton abundance. During the winter mixing phase, a lower C org flux was recorded in the upper trap samples which was a consequence of the reduced growth of phytoplankton and the transport of the cells to the deeper aphotic layers; where some increase of org C flux in the lower trap was recorded. Thus, the deepest layers were enriched leading to a minimum vertical zooplankton-migration (DVM). In spring, during the post-convection period (March, April), high abundance of mesozooplankton, mostly copepods, was registered in the upper layer, as well as an evident increase of C org flux. Other species than copepods (which remain at the food rich surface), probably ostracods and euphausiids, played a significant role in the DVM because they are more abundant in the deeper layers. The increase in C org flux in the upper samples in May is in accordance with a recorded salp bloom (also evident through a strong backscatter signal). Salp fecal pellets were observed to contribute significantly to vertical carbon flux in various ocean regions.

The relationship between vertical zooplankton distribution, zooplankton migration and carbon export has generally been poorly studied in the Adriatic Sea. Preliminary results for the open SA are presented here, but for more accurate knowledge of this topic, a long term study is needed.
Exploring Mesozoic Climates - Modeling and Evaluation of Proxy Distributions
Authors: Landwehrs Jan , Feulner Georg , Hofmann Matthias , Petri Stefan , Sames Benjamin , Wagreich Michael
Published: March 2020

The Mesozoic Era (~252-66 Ma) is a decisive period in Earth’s history. It is marked by a tectonic transition from the Pangea supercontinent towards a modern continental configuration as well as the ecological success of the dinosaurs and the evolution of mammals, flowering plants, stony corals and important groups of planktic calcifiers. The Mesozoic is generally considered as a greenhouse climate period, with especially high global temperatures during the Triassic and the Late Cretaceous. Here, we present novel modeling results on the evolution of global climatic conditions through the Mesozoic.

An ensemble of equilibrium climate states for 40 geological timeslices between 255 and 60 Ma is simulated with the CLIMBER-3α Earth System Model of Intermediate Complexity. The influence of changing paleogeography, sea level, vegetation cover, solar luminosity, orbital configuration and atmospheric CO2 concentration is systematically tested based on constraints from published geological proxy reconstructions and previous modeling work.

Atmospheric pCO2 is found to be the strongest driver of global mean temperatures, which are generally elevated above the present and reach ≥20°C in the Late Triassic to Early Jurassic and the mid-Cretaceous if a recently published pCO2 proxy compilation is employed. The simulated seasonal latitudinal shift of high precipitation zones exhibits a maximum during the mid-Triassic to Early Jurassic and therefore supports the notion of a “Megamonsoon” during this time. Simulated humid and arid climate zones generally agree well with spatial distributions of geologic climate indicators like coal and evaporites, although some discrepancies exist. The same applies to the correlation of fossil stony coral reef distributions with regions where seawater temperatures would have been suitable for (modern) coral reefs. We will discuss which changes of Earth System parameters throughout the Mesozoic can best explain shifts in these distributions.
Human exposure assessment to air pollutants: application of a new portable air monitoring instrument
Authors: Ye Sheng , Wenig Mark
Published: March 2020

Air pollution has been gaining increasing global attention. The public is concerned about urban pollution levels including both in- and outdoor air quality. A handheld Air Quality Inspection Box (Airquix) was developed in order to monitor air pollutants in real-time, and determine individual exposure to different pollutants in different environments. The Airquix is equipped with air quality sensors: electrical chemical NO2, O3, NO sensors, NDIR CO2 sensor, OPC-N3 PM sensor; environment sensor (T, RH, P), GPS sensor and a raspberry pi for data logging, processing and display. To achieve a relatively high accuracy, e.g. +/- 5ppb at 5 seconds time resolution for the NO2 concentration, the pre- and post- calibration for the Airquix were performed by comparison with high-end air monitoring instruments. In this study, several Airquixes were distributed to different persons to assess individual exposure. The daily activities were distinguished by different commutes, in- and outdoor behaviors, the personal habits and potential episodes. The resulting data set can be used for the assessment of health impacts.
Using Commercial Microwave Links for a stochastic reconstruction of precipitation field ensembles
Authors: Haese Barbara , Hörning Sebastian , Graf Maximilian , Eshel Adam , Chwala Christian , Kunstmann Harald
Published: March 2020

Precipitation is one of the crucial variables within the hydrological system, and accordingly one of the main drivers for terrestrial hydrological processes. The quality of many hydrological applications such as climate prediction, water resource management, and flood forecasting, depends on the correct reproduction of its spatiotemporal distribution. However, the global network of precipitation observations is relatively sparse in large areas of the world. Compared to these observation network, inhabited areas typically have a relative dense network of Commercial Microwave Links (CMLs). These CMLs can be used to calculate path-averaged rain rates, derived from their attenuation. One challenge when using path-averaged rain rates is the construction of spatial precipitation fields. To address these challenges, we apply Random Mixing Whittaker-Shannon (RMWSPy) to stochastically simulate precipitation fields. Therefore, we generate precipitation fields as a linear combination of unconditional spatial random fields, where the spatial dependence structure is described by copulas. The weights of the linear combination are optimized in such a way that the observations and the spatial structure of the precipitation observations are reproduced. Within this method the path-averaged rain rates are used as non-linear constrains. One big advantage when using RMWSPy is the ability to simulate precipitation field ensembles of any size, where each ensemble member is in concordance with the underlying observations. The spread of such an ensemble enables an uncertainty estimation of the simulated fields. In particular, it reflects the precipitation variability along the CML path and the uncertainty between the observation locations. We demonstrate RMWSPy using CML observations within various areas of Germany with a different density of observations. We show, that the reconstructed precipitation fields reproduce the observed spatial precipitation pattern in a comparable good quality as the RADOLAN weather radar data set provided by the German Weather Service (DWD).
Progressive landslide activity analysis and monitoring from Multi-temporal high-resolution geoinfomatic data sets
Authors: Chang Kuo-Jen , Tseng Chih-Ming , Chang Ho-Hsuan , Huang Mei-Jen
Published: March 2020

Due to the high seismicity and high annual precipitation, numerous landslides have occurred and caused severe impact in Taiwan. In recent years, the remote sensing technology improves rapidly, providing a wide range of image, essential and precise geoinformation. The Small unmanned aircraft system (sUAS) has been widely used in landslide monitoring and geomorphic change detection. To access potential hazards we combine sUAS, field survey, terrestrial laser scanner (ground LiDAR) and UAS LiDAR for data acquisition. Based on the methods we construct multi-temporal high-resolution DTMs so as to access the activity and to monitoring the creeping landslides in Paolai village, southern Taiwan. The data set are qualified from 21 ground control points (GCPs) and 11 check points (CPs) based on real-time kinematic-global positioning system (RTK-GPS) and VBS RTK-GPS (e-GNSS). Since 2015, more than 10 geospatial datasets have been produced for an area between 5-80 Km2 with 8-12 cm spatial resolution. These datasets were then compared with the airborne LiDAR data to access the quality and interpretability of the data sets. Since 2017, we integrate UAS LiDAR to monitoring landslide area, and re-evaluate the data accuracy. Since 2018 we have integrate UAS LiDAR, terrestrial LiDAR, and photogrammetric point cloud for landslide study, to ensure no shadow effect of the dataset. The geomorphologic changes and landslide activities were quantified in Paolai area. The results of this study provide not only geoinfomatic datasets of the hazardous area, but also for essential geomorphologic information for other study, and for hazard mitigation and planning, as well.
Ecological footprint analysis for urban agglomeration sustainability in the middle stream of the Yangtze River
Authors: Wang Hongqi
Published: March 2020

How to balance ecosystem health and economic development is essential to study sustainability of urban ecosystems. Many methods for assessing urban sustainability have been developed, among which ecological footprint analysis (EFA) has been widely applied as a promising policy and planning tool. This paper proposed a modified EFA with the local ecological footprint being justified by adapting equivalence and yield factors in context of net primary productivity (NPP) from the Miami model. Biodiversity reserves were also incorporated using GIS technology and synthetic assessment of attributes to reflect various eco- logical functions. In addition, ecological footprint deficit (EFD), implying that the productive land cannot sustain current levels of consumption for a given population, was used to reveal the extent of ecological debt, while the ecological footprint variation index (EFVI) was proposed to describe the tradeoffs between real consumption and the carrying capacity of a specific region. A case study of urban areas in the middle stream of the Yangtze River Basin showed that the per capita EFD of the Wanjiang urban belt, central Poyang Lake urban agglomeration, suburban Poyang Lake urban agglomeration, Wuhan megalopolis, Jingmen–Jingzhou–Yichang urban agglomeration, central Changsha–Zhuzou–Xiangtan urban agglomeration, and suburban Changsha–Zhuzou–Xiangtan urban agglomeration increased by 64.83%, 178.05%, 214.82%, 59.08%, 71.68%, 100.62%, and 91.06% between 2000 and 2010, respectively. The local ecological footprint pressure index (EFPI) was classified into five levels. The Poyang lake urban agglomeration was found to be in a slight deficit, while all others were in a severe deficit in 2010. Calculations of EFVI also revealed that the booming urbanization occurred at great cost to the deteriorating ecosystems between 2000 and 2010. Accordingly, relevant influence factors were investigated using a forward stepwise regression method, which indicated that ecological deficit was positively correlated with GDP, population density, and emission of industrial waste, but negatively correlated with the tertiary industry.