bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of anomalies and trends in IGRA, RHARM, and ERA5 temperature, humidity and wind time series
Authors: Madonna Fabio , Sy Souleymane , Amato Francesco , Franco Luigi , Gagliardi Simone , Marra Fabrizio , Proto Monica , Rosoldi Marco , Tramutola Emanuele
Published: March 2020

Upper-air radiosounding observations of temperature, relative humidity and wind are a of the primary data source for climate studies. Nevertheless, historical radiosounding time series are affected by several systematic uncertainties due to change in the measurement sensors. 

In the frame of the Copernicus Climate Change Service (C3S), a novel approach, named RHARM (Radiosounding HARMonization), has been developed to homogenize temperature, humidity and wind radiosounding profile time series available from the the Integrated Global Radiosonde Archive (IGRA) and provide an estimation of the total uncertainty for each single profile. RHARM is an alternative to the few existing approaches.

RHARM is applied to daily (0000 and 1200 UTC) radiosonde data on 16 standard pressure levels (10, 20, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 700, 850, 925, 1000 hPa) for the IGRA data from 1978 onward. Relative humidity (RH) adjustments is limited to 300 hPa owing to pervasive sensor performance issues at greater altitudes. The bias adjustments are estimated at mandatory levels only but they are also interpolated to the significant levels reported within each individual ascent profile.

This paper discusses the comparison of the monthly anomalies and trends estimated at different latitudes and pressure levels for ERA5, IGRA and RHARM. Trends are esitmated using a robust least absolute deviation method. ERA5 is the latest climate reanalysis produced by ECMWF providing hourly data on on regular latitude-longitude grids at 0.25° x 0.25° resolution, with atmospheric parameters on 137 pressure levels (available on https://cds.climate.copernicus.eu).

Differences in the comparisons among the three datasets will be discussed along with the analysis of the trends observed in the considered time series. To evaluate its homogeneity and stability, the uncertainty estimation provided in RHARM will be also compared with O-B field obtained using the to ECWMF operational forecast model as the background.
The structural evolution of the Falkland Plateau
Authors: Stanca Roxana Mihaela , Paton Douglas , Mortimer Estelle , Hodgson David , McCarthy Dave
Published: March 2020

The palaeogeographic reconstruction of the Falkland Plateau transform margin in a Gondwana pre-break-up configuration has been the subject of debate for years. This is mainly due to the uncertainty in the position of the Falkland Islands microplate. The islands were an extension of the south-east coast of South Africa, being either i) part of a rigid Falkland Plateau fixed to the South American plate or ii) undergoing a vertical-axis clockwise rotation of between 80° to 120° along the transform faults generated during the initial stages of fragmentation of south-western Gondwana. The absence of documented evidence of this rotation within the sedimentary infill of the basins surrounding the Falkland Islands represents an ongoing issue. Furthermore, a structural framework of the eastern continental shelf of the islands that takes into account the most recent seismic reflection surveys has not been published yet.

This study presents an updated description of the structural configuration of the Falkland Plateau Basin, focusing on the Volunteer and Fitzroy sub-basins. This structural framework, based on extensive 2D and 3D seismic reflection data and aided by seismic attribute mapping, provides new insights into the evolution of the Falkland Islands microplate and the Falkland Plateau Basin.

Three main structural trends were identified across this section of the Falkland Plateau. WNW-ESE trending half-grabens were mapped north-west of the Volunteer sub-basin; these correlate laterally with linear gravity anomalies following the same trend north of the Falkland Islands. NNE-SSW to N-S normal faults are predominant west of the Volunteer sub-basin and are believed to control the western margin of the Falkland Plateau Basin. Locally, the NNE-SSW trend is subdued by NNW-SSE striking en-échelon normal faults suggestive of left-lateral movement along a NNE-SSW direction. A similar trend is interpreted in the southern part of the Fitzroy sub-basin, supporting sinistral wrenching along the western margin of the Falkland Plateau Basin.

These results suggest intra-plate deformation that is consistent with a clockwise rotation of the Falkland Islands microplate along the transform faults that accommodated the initial fragmentation of Gondwana. The interpreted fault network allows us to understand the temporal variation in the orientation of the minimum horizontal stress across the Falkland Islands microplate. By comparing this variation with the regional stress regime in south-western Gondwana, the timing and mechanism of the rotation of the islands can be better constrained.
Integrated geophysical analysis of the April 2017 Moiyabana intra-plate earthquake, Botswana
Authors: Moorkamp Max , Atekwana Estella , Fadel Islam , Gabriel Alice-Agnes , Kolawole Folarin , Shemang Elisha , Ramotoroko Calistus , van der Meijde Mark , Mickus Kevin , Selepeng Ame , Molwalefhe Loago
Published: March 2020

The 3 April 2017 Moiyabana intra-plate earthquake in central Botswana occurred in a region that, until then, had been assumed to be seismically quiet. Its location away from the East African Rift system in a Proterozoic mobile belt between Archean Cratons has raised questions on the triggering mechanism and sparked various studies investigating the crustal and mantle structure in the region, the focal mechanism and the displacement associated with the event. Aeromagnetic and magnetotelluric data indicate movement on a NW striking and NE dipping fault. However, the details of the fault geometry differ when analysing each dataset independently. The geophysical inversion results plus reconstructions of fault movement from InSAR data are all compatible with normal movement and reactivation of a previous thrust fault. An open question though is to which degree fluids are responsible for triggering the event. Here we present first results of reconciling the different available datasets in an integrated analysis. We will show an updated geophysical model of the region around the hypocenter. Such a model can help to shed light on the rupture processes during the earthquake and forms a first step to unravel the genesis of this intra-plate event.
Recent patterns of discharge and sediment output of the Gorner Glacier, Switzerland
Authors: Prasicek Günther , Mettra François , Lane Stuart , Herman Frédéric
Published: March 2020

Recent climate change is causing rapid retreat of alpine glaciers around the globe. As ice melts and glaciers thin, glacier motion and subglacial processes will change. One of the most relevant aspects for down-valley environments, settlements and infrastructure is the potential change in flow discharge and sediment output.

Here we present the results of an ongoing monitoring program at the Gorner Glacier, Switzerland, the second-largest glacier system in the European Alps.  During the melt season of 2018 and 2019, stage and turbidity were monitored with a 5 minute frequency along a turbulent section of the glacial river, located approximately 1 km downstream of the glacier terminus. For calibration of the turbidity measurements, daily water samples were obtained with an automated pump sampler, supported by additional intermittent manual sampling. The data is complemented by a discharge time series that also contains information on the flushing of a bedload trap at the hydro power weir located about 2 km downstream of the glacier terminus. The discharge and flushing data have a resolution of 15 minutes.  Turbidity and discharge allow estimation of the output of suspended load, while the flushing data inform about bedload. We further measured total organic carbon content of the water samples to infer the water and sediment source.

Data suggest a clear seasonal pattern, not only in discharge and sediment output, but also in suspended sediment concentration (SSC). While SSC is high during snow melt and in early summer, it decreases rapidly in July and stays at similar levels until September. This may indicate exhaustion of sediment storage beneath the glacier, but could also result from a change in subglacial regime, e.g. from a decrease in subglacial water pressure due to the progressive opening of subglacial cavities during the melt season. High fractions of organic carbon, presumably due to lateral sediment input from hillslopes, occur during storms throughout the entire season.
Estimating fuel consumption of cars based on movement data and its sensitivity to car and movement specific properties
Authors: Pontius Martin , Gräler Benedikt , Remke Albert , de Wall Arne
Published: March 2020

The transportation sector is responsible for approximately 20 percent of global CO2 emissions of which most of them are produced by road traffic. Moreover, emissions are rising and are rising faster than in other sectors. Reducing these emissions will be crucial to reach the goals of the 2016 Paris agreement. Efficient reduction strategies and their monitoring rely on broad and exact data about passenger car fuel consumption and emissions.

To encourage people to drive eco-efficiently and to collect traffic data the open Citizen Science Platform enviroCar (https://enviroCar.org) had been initiated. Data from the internal vehicle's communication bus can be sent to the enviroCar Android App via an OBD-Bluetooth adapter and the data can be anonymised and uploaded as open data to the enviroCar server. Fuel consumption - and thus also emissions - are conventionally calculated from motor-specific data like mass-air-flow. One drawback of this approach is that users need to have an OBD adapter installed to get these specific data. An easier and broader use of the app is achieved by basing the calculation of energy consumption on movement data only which can be measured by GPS sensors in many mobile phones.

We present such a purely GPS-based approach and means to assess the sensitivity of the resulting fuel consumption to parameters of the vehicle and the movement pattern. The analyzed vehicles and track patterns show a high degree of heterogeneity regarding size and weight of vehicles and driven speed, acceleration and road gradient. In total, 51 tracks from the open enviroCar server covering 7600 km within 95 hours were analyzed.

The calculation is done using simple physical laws and is very lightweight, yet the fuel consumption values are relatively precise when compared to the OBD data based approach. The differences of fuel consumption per 100 km are typically below 1 l. Only for tracks which include a significant amount of stop-and-go characteristics, the observed discrepancies exceed 1 l.

The approach can also be adapted to electric cars as it is load-based. In this case, a recuperation model has to be included and the model to calculate efficiency has to be adapted.
The Feasibility of Photovoltaic Pumping System For Apple Orchards Irrigation in Loess Plateau
Authors: Sun Miao , Zhao Xining , Gao Xuerui , Wang Yubao
Published: March 2020

Rainwater collection and utilization is a common method to relieve soil water pressure in dry dryland orchards. Due to relatively low levels of economic development and population distribution, these areas are unable to develop electricity or import large amounts of energy, resulting in rainwater harvesting often not being fully utilized. Photovoltaic (PV) pumping system is an effective way to ensure the sustainable utilization of soil water in apple orchards. In order to explore the application potential of PV pumping system in the apple suitable area of the loess plateau, this study simulates the rainwater collection amount and the orchard water demand change process in typical hydrological years and conducts a feasibility analysis of the PV pumping system from both technical and economic perspectives. The results found that the precipitation from June to October could not meet the water requirement of the growth of apple tree in the demonstration orchard and the total annual water demand reaches 170 m³. Fortunately, the local solar energy resources can basically meet the demand for solar energy in the PV pumping irrigation system, which ensures sufficiently irrigation water for the apple trees grow. After the completion of the PV pumping irrigation system, the income from the increase in fresh grass production in the demonstration area will reach 8019 CNY/year. The ratio of investment to income is 1:3.0. The investment recovery period is 4 years and it has good economic feasibility. Finally, using spatial geographic information technology, the apple-adapted area is systematically matched with the most suitable planting area for solar irrigation. The land area suitable for solar technology irrigation accounts for 47.6% of the total area, showing promising prospects to be popularized in Western China at large scale.

KEY WORDS: photovoltaic pumping System; Loess plateau; economic benefit; application potential; Apple orchards
Towards an automatic algorithm for natural oil slicks delineation using Copernicus Sentinel-1 imagery
Authors: Vrinceanu Cristina , Marsh Stuart , Grebby Stephen
Published: March 2020

Radar imagery, and specifically SAR imagery, is the preferred data type for the detection and delineation of oil slicks formed following the discharge of oil through human activities or natural occurrences. The contrast between the dark oil surfaces, characterized by a low backscatter return, and the rough, bright sea surface with higher backscatter has been exploited for decades in studies and operational processes.

Despite the semi-automatic nature of the traditional detection approaches, the workflow has always included the expertise of a trained human operator, for validating the results and efficiently discriminating between oil stained surfaces and other ocean phenomena that can produce a similar effect on SAR imagery (e.g., algal blooms, greasy ice). Thus, the process is time and resource consuming, while results are highly subjective. Therefore, automating the process to reduce the time for processing and analysis while producing consistent results is the ultimate goal.

Addressing this challenge, a new algorithm is proposed in this presentation. Building on state-of-the-art methods, the algorithm makes use of the latest technological developments for processing and analyzing features on the ocean surface using a synergistic approach combining SAR, optical and ancillary datasets. 

This presentation will focus on the results that have been obtained by ingesting high-resolution open SAR data delivered by the Copernicus Sentinel-1 satellites into the algorithm. This represents a significant advancement over traditional approaches both in terms of utilizing contemporary SAR mission imagery instead of that from the heritage missions (ERS, ENVISAT), and in deploying both conventional classification and artificial intelligence techniques (e.g. CNNs) .

The scope of this study also involves highlighting the strengths and shortcomings of each type of technique in relation to the scenario to help make recommendations on the appropriate algorithm to utilize. The full architecture of the SAR component of the algorithm will be detailed, while the case study results over a set of known seepage sites and potential candidate sites will be presented, demonstrating the reliability of this new method.
Seismogenic structures in western Yunnan revealed by three-dimensional magnetotelluric imaging
Authors: Huang Qinghua , Ye Tao , Chen Xiaobin
Published: March 2020

Influenced by the extrusion of Tibetan blocks and Indo-Burmese collision, the region in western Yunnan is associated with active seismicity and Quaternary volcanoes. Based on broadband magnetotelluric data collected in western Yunnan, we obtain a three-dimensional crustal electrical resistivity model after various data processing and three-dimensional inversion test. The above resistivity model reveals the seismogenic structures of the moderate and strong earthquakes in this tectonic region. We investigate the possible relationship between the seismicity and the electrical structure in western Yunnan region. The results indicate that earthquakes in this region tend to occur in the transition zone between the resistive and conductive structures. Our results also show that one resistive body imaged at the mid-lower crust may have blocked the previously proposed crustal channel flow along this intra-continental block boundary to the east of Tibetan Plateau. Our resistivity model suggests a bifurcation of the crustal flow in western Yunnan. This bifurcated crustal flow structure may play an important dynamical role in the seismogenesis of the earthquakes in western Yunnan.
Estimating future changes in Alpine flash floods using CP-RCM projections
Authors: Sperna Weiland Frederiek , Viguurs Pety , Zander Marjanne , Weerts Albrecht
Published: March 2020

Flash floods are a significant natural hazard in the Alpine region (FOEN, 2010). With changing rainfall regimes and decreased snow accumulation due to climate change, the risk of flash flood occurrence and timing thereof could change as well (Etchevers et al., 2002).

In this study the frequency and occurrence of flash floods in the Alpine region is estimated for current and future climate (RCP8.5) using state-of-the-art high-resolution convection permitting climate models (CP-RCMs). For the historical period and far future (2100), data from an ensemble of convection permitting climate models (Ban et al., submitted 2019) was used to drive a high-resolution distributed hydrological model, i.e. the wflow_sbm model (Imhoff et al., 2019, Verseveld et al., 2020). The model domains cover the mountainous parts of the Danube, Rhone, Rhine and Po located in the Alps.  The CP-RCM time-series available are of limited length due to computational constrains. At the same time the locations of flash floods vary per year therefore a regional scale analysis is made to assess whether in general the severity, frequency and timing of flash floods in the Alps will likely change under changing climate conditions.

This research is embedded in the EU H2020 project EUCP (EUropean Climate Prediction system) (https://www.eucp-project.eu/), which aims to support climate adaptation and mitigation decisions for the coming decades by developing a regional climate prediction and projection system based on high-resolution climate models for Europe.

References:

Etchevers, P., Golaz, C., Habets, F., and Noilhan, J., Impact of a climate change on the Rhone river catchment hydrology, J. Geophys. Res., 107( D16), doi:, 2002.

Federal office for the environment FOEN (2010) Environment Switzerland 2011, Bern and Neuchatel 2011. Retrieved from www.environment-stat.admin.ch

Imhoff, R.O., W. van Verseveld, B. van Osnabrugge, A.H. Weerts, 2019. Scaling point-scale pedotransfer functions parameter estimates for seamless large-domain high-resolution distributed hydrological modelling: An example for the Rhine river. Submitted to Water Resources Research, 2019.

N. Ban, E. Brisson, C. Caillaud, E. Coppola, E. Pichelli, S. Sobolowski, …, M.J. Zander (submitted 2019): “The first multi-model ensemble of regional climate simulations at the kilometer-scale resolution, Part I: Evaluation of precipitation”, manuscript submitted for publication.
Data driven methods for real time flood, drought and water quality monitoring: applications for Internet of Water
Authors: Pagán Brianna , Desmet Nele , Seuntjens Piet , Bollen Erik , Kuijpers Bart
Published: March 2020

The Internet of Water (IoW) is a large-scale permanent sensor network with 2500 small, energy-efficient wireless water quality sensors spread across Flanders, Belgium. This intelligent water management system will permanently monitor water quality and quantity in real time. Such a dense network of sensors with high temporal resolution (sub-hourly) will provide unprecedented volumes of data for drought, flood and pollution management, prediction and decisions. While traditional physical hydrological models are obvious choices for utilizing such a dataset, computational costs or limitations must be considered when working in real time decision making.

In collaboration with the Flemish Institute for Technological Research (VITO) and the University of Hasselt, we present several data mining and machine learning initiatives which support the IoW. Examples include interpolating grab sample measurements to river stretches to monitor salinity intrusion. A shallow feed forward neural network is trained on historical grab samples using physical characteristics of the river stretches (i.e. soil properties, ocean connectivity). Such a system allows for salinity monitoring without complex convection-diffusion modeling, and for estimating salinity in areas with less monitoring stations. Another highlighted project is the coupling of neural network and data assimilation schemes for water quality forecasting. A long short-term memory recurrent neural network is trained on historical water quality parameters and remotely sensed spatially distributed weather data. Using forecasted weather data, a model estimate of water quality parameters are obtained from the neural network. A Newtonian nudging data assimilation scheme further corrects the forecast leveraging previous day observations, which can aid in the correction for non-point or non-weather driven pollution influences. Calculations are supported by an optimized database system developed by the University of Hasselt which further exploits data mining techniques to estimate water movement and timing through the Flanders river network system. As geospatial data increases exponentially in both temporal and spatial resolutions, scientists and water managers must consider the tradeoff between computational resources and physical model accuracy. These type of hybrid approaches allows for near real-time analysis without computational limitations and will further support research to make communities more climate resilient.
Global maps of current and future nitrogen mineralization
Authors: Maschler Julia , Maynard Daniel S. , Routh Devin , van den Hoogen Johan , Li Zhaolei , Niu Shuli , Crowther Thomas W.
Published: March 2020

Soil nitrogen is a prominent determinant of plant growth, with nitrogen (N) availability being a key driver of terrestrial carbon sequestration. The local availability of soil N is thus crucial to our understanding of broad-scale trends in soil fertility, productivity, and carbon dynamics. Here, we provide global, high-resolution maps of current and future (2050) potential net nitrogen mineralization (N-min), revealing global patterns in soil N availability. Highest mineralization rates are found in warm and moist tropical regions, leading to a strong latitudinal gradient in N-min. We observed a positive correlation of N-min rates with human population density and net primary productivity. Projected climate conditions for 2050 suggest that N availability will further decrease in areas of low N availability and increase in areas of high N availability, thereby intensifying current global trends. These results shed light on the core processes governing productivity at a global scale, providing an opportunity to improve the accuracy of plant biomass and climate models.
The strange instability of the equatorial Kelvin wave
Authors: Griffiths Stephen
Published: March 2020

The Kelvin wave is perhaps the most important of the equatorially trapped waves in the terrestrial atmosphere and ocean, and plays a role in various phenomena such as tropical convection and El Nino. Theoretically, it can be understood from the linear dynamics of a stratified fluid on an equatorial β-plane, which, with simple assumptions about the disturbance structure, leads to wavelike solutions propagating along the equator, with exponential decay in latitude. However, when the simplest possible background flow is added (with uniform latitudinal shear), the Kelvin wave (but not the other equatorial waves) becomes unstable. This happens in an extremely unusual way: there is instability for arbitrarily small nondimensional shear λ, and the growth rate is proportional to exp(-1/λ^2) as λ → 0. This in contrast to most hydrodynamic instabilities, in which the growth rate typically scales as a positive power of λ-λc as the control parameter λ passes through a critical value λc.

This Kelvin wave instability has been established numerically by Natarov and Boyd, who also speculated as to the underlying mathematical cause by analysing a quantum harmonic oscillator perturbed by a potential with a remote pole. Here we show how the growth rate and full spatial structure of the Kelvin wave instability may be derived using matched asymptotic expansions applied to the (linear) equations of motion. This involves an adventure with confluent hypergeometric functions in the exponentially-decaying tails of the Kelvin waves, and a trick to reveal the exponentially small growth rate from a formulation that only uses regular perturbation expansions. Numerical verification of the analysis is also interesting and challenging, since special high-precision solutions of the governing ordinary differential equations are required even when the nondimensional shear is not that small (circa 0.5). 
What is the relationship between water storage change and NDVI?
Authors: Mankar Vedashree , Jhaj Ajayraj Singh , Jain Samyak , Devaraju Balaji
Published: March 2020

The fluctuation in vegetation is affected by water availability, while on the same hand vegetation also influences regional water balance. A better understanding of the relationship between variation in vegetation state and water storage change would help explain the complicated interactions between vegetation dynamics and regional water balance. We use total water storage change from the Gravity Recovery and Climate Experiment (GRACE) and its successor mission GRACE Follow-On (GRACE-FO) and Normalised Difference Vegetation Index (NDVI) data from Advanced Very High Resolution Radiometer (AVHRR). First, we bring the two datasets to a comparable resolution and then we aggregate the two datasets over the 37 sub-catchments of the Ganga basin. The Pearson correlation coefficient was very high (R > 0.5) for 35 of the 37 sub-catchments when the full signals were used, indicating that the seasonality signals have a high correlation. Once the seasonal signal was removed, the Pearson correlation coefficient became insignificant. We will look into the causes of the lack of correlation between the two residual signals and also perform an autocorrelation analysis to identify the lag between the two variables.
Hydrological basin connectivity in a low-latitude rift: the impact of the Holocene African Humid Period (AHP) on fluvial activity and species dispersal in the Kenya Rift, East African Rift System (EARS)
Authors: Dommain René , Riedl Simon , Olaka Lydia , deMenocal Peter , Deino Alan , Potts Richard , Strecker Manfred
Published: March 2020

As a result of sustained tectonic and magmatic processes throughout the latter half of the Cenozoic, the eastern branch of the EARS exhibits an extensional tectonic system with pronounced relief contrasts, constituting both corridors and barriers for species dispersal. The tectono-magmatic history has generated a region of highly variable topography that results in widely varying amounts of rainfall and vegetation cover. Today, the generally dry eastern branch of the EARS hosts numerous sub-basins and adjacent local high-relief areas that are hydrologically isolated, with unique microclimates, vegetation types, faunas and superposed surface processes. However, during episodes of climate change with a trend toward more humid conditions, many of these basins hosted freshwater lakes that were hydrologically connected. These areas have repeatedly exhibited freshwater conditions and likely served as gateways and migration corridors mainly for aquatic organisms, in particular fish, facilitating population expansion, dispersal and gene flow.

Here, we analyze the manifold manifestations of the AHP in Kenya and adjacent sectors of the EARS to establish the timing and spatial extent of a paleo-drainage system documented by lake shorelines, deltas, overflow channels and sediments. These vestiges of fluvial connectivity in the rift have emerged as analogs for recurrent Pleistocene episodes with high lake levels and inter-basin linkage that repeatedly connected equatorial basins with regions to the north and south, respectively. For example, fossil evidence for the Pleistocene occurrence of the Nile crocodile (Crocodylus niloticus) as far south as equatorial Lake Bogoria (Kenya) and its present occurrence in the now closed Lake Baringo basin indicate fluvial connectivity over several degrees of latitude during more humid episodes in the past. Similarly, the occurrence of more than a dozen of the same fish species in the presently unconnected Lakes Albert and Turkana is likely due to a mutual connection during the AHP when Lake Turkana was overflowing into the White Nile.

Taken together, the divergent fossil and modern faunal evidence and geomorphic and sedimentological evidence of contrasting hydrological conditions between the wet AHP and the present, suggest that the conditions during the AHP provides a template of fluvial connectivity and potential dispersal patterns for earlier humid phases during the Plio-Pleistocene.
Analysis of carbon sequestration sensitivity to recent changes in land use patterns over Belgium using a combination of models and remote sensing techniques
Authors: Verma Arpita , Jacquemin Ingrid , Francois Louis , Dendoncker Nicolas , Beckers Veronique , Hamdi Rafiq , Berckmans Julie , Hallot Eric
Published: March 2020

Changes in land use/land cover (LU/LC) practices are critical to determine and this is one of the crucial driving forces of terrestrial ecosystem productivity and carbon sink variability. However, relatively few studies have quantified the impact of LU/LC change on the terrestrial carbon cycle. In the present study, we developed a workflow for quantifying and assessing changes in terrestrial carbon stocks due to land use change using a dynamic vegetation model. The main objectives are to assess status and variation in carbon stocks across land covers, towards the quantification of spatial distribution and dynamic variation of terrestrial carbon sinks in response to LU/LC change. Here, with the CARAIB dynamic vegetation model, we perform simulations using several sets of LU/LC data to analyse the sensitivity of the carbon sink. We propose a new method of using satellite – and machine learning-based observation to reconstruct historical LU/LC change and compare it with static data from the cadastral map and dynamic data from an agent-based model coupled with CARAIB. It will quantify the spatial and temporal variability of land use during the 2000-2019 period over Belgium at high resolution. This study will give the space to analyse past information and hence calibrate the dynamic vegetation model to minimize uncertainty in the future projection (until 2035). Overall, this study allows us to understand the effect of changing land use pattern and identify the input dataset which minimizes the uncertainty in model estimation.
Infrasound signals from a ground-truth source and implications from atmospheric models: ARIANE engine tests in Southern Germany revisited
Authors: Koch Karl , Pilger Christoph
Published: March 2020

Over the past two decades the German Aerospace Center (DLR) facility near Heilbronn, Germany, has conducted a considerable number of tests of the ARIANE-5 main engine. Infrasound signals from many of these tests (~40%) have been observed at IMS station IS26 at a distance of about 320 km in an easterly direction (99° east-southeast from North). Due to the prevailing weather pattern in Central Europe, nearly all detected tests occurred during the winter months from October to April, when the stratospheric wind points in an eastern direction, while it reverses during the summer season. Except for a single event in May 2012, the summer months (May through September) did not yield any infrasound signal detections from the engine tests. On the other hand, not all tests conducted in winter are observed either, while detection in the spring and fall equinox months of April and October must be considered to occur incidentally.
 
The large database of about 160 engine tests enables us to assess how well propagation modelling based on a standard atmospheric specification such as the ECMWF forecast model conforms with observed detections and non-detections.  While reversal of the stratospheric wind pattern in the summer season eliminates the stratospheric duct towards the eastern direction, the case of non-detections in the winter season may be of a more subtle nature. Besides increases in background noise levels due to heavy winds at the station, the fine structure of the stratospheric duct in the atmospheric model should determine the detection capability at IS26, which could be located inside or outside a shadow zone at a specific time. Ultimately, the standard atmospheric model used may not be an accurate description of the atmosphere in such cases either. This work on a controlled ground truth infrasound source will thus increase our understanding on the relationship between infrasound detection capabilities and atmospheric specifications over the seasons.
The effect of soil temperature and soil water content on thermal properties in an artificial forestland and a natural regrowth grassland
Authors: Zhang Tangtang , Ma Xin
Published: March 2020

Soil temperature, soil water content and soil thermal properties were measured in an artificial forestland and a natural regrowth grassland from November in 2017 to July in 2019. The results show that the effects of soil temperature and soil water content on thermal properties are different in different soil condition. Soil thermal conductivity (K) and soil volumetric heat capacity (C) increase with increasing temperature in unfrozen period, but soil diffusivity (D) has no significant dynamic cycle and it almost keeps a constant level in a certain time. Soil thermal conductivity (K) decreases with increasing temperature during soil frozen period. The C and K increase with increasing soil water content in unfrozen period, while the D decrease with increasing soil water content.
Innovative Drone-based Hyperspectral Detection of Heavy Metals (Ni, Zn, and Cu) in Plants cultivated for Phytomining
Authors: Klos Friederike , Sut-Lohmann Magdalena , Raab Thomas , Hirsch Florian
Published: March 2020

Natural and anthropogenic activities can result in soil contamination and thus disturb their important functions for the abiotic and biotic environment, e.g. filtering, buffering or plant growth. Specific remediation measures are already taken for such environmental issues including phytoremediation using plants that are able to reduce heavy metal concentrations in the pedosphere and accumulate these heavy metals in their biomass. A fast monitoring system for a large-scale and area-wide mapping of metal contents in plants is still missing. However, such a monitoring system would be a very helpful tool to the recycling of heavy metals and supports the development of environmentally friendly processes for metal recovery. We present the concept of the innovative HyPhy project, which studies the possibility of monitoring heavy metal accumulation in hyperaccumulators with drone-based hyperspectral sensors. The phytoscreening considered here can be used to profitably mine raw materials such as nickel, zinc and copper using hyperaccumulating plants. Method will be validated using green house and field measurements based on hyperspectral sensors supported by drones. Two sensors will be used, the VNIR hyperspectral sensor from Cubert GmbH (450-950nm) and the SWIR hyperspectral sensor HySpex from the Norwegian company NEO (1000-2500nm). The two optical sensors are validated with the point spectrometer PSR+ from Spectral Evolution (350-2500nm). This presentation will show background, methods and first results of our project.

 
Spatiotemporal patterns of short-duration heavy precipitation in Germany
Authors: Haacke Nasrin , Paton Eva Nora
Published: March 2020

Heavy rainfall events and the high variability of their occurrence have a significant effect on the urban water cycle and are commonly thought to increase in the future. The increasing risk of urban flash floods is a problem jointly faced by the urban infrastructure, water networks and -systems. A better understanding of the diurnal and seasonal precipitation cycles of short-duration heavy rainfall events is therefore required. This study presents the diurnal and seasonal distribution of those events (10-minute and one-hour) in Germany and puts them into a spatial context. Precipitation data from 22 weather stations of the German Weather Service were statistically examined for the period 2000 - 2018. In addition, the spatial and temporal distribution patterns were compared to spatiotemporal patterns of various controlling factors. Three diurnal distribution patterns can be identified: 1) a homogeneous distribution of events over a maximum period of 24 hours in the S-SW, 2) a non-uniform grouping of events in the morning and afternoon predominantly in the NE and 3) an occurrence of heavy rainfall events in the afternoon in a much shorter time interval in the North. These patterns are not necessarily identical for both event durations and suggest different forms and degrees of drivers. From a seasonal perspective, events of both durations occur exclusively between May and September, with the majority occurring in July and August. Temporal distributions can mainly be explained by controlling factors such as sunshine duration and intensity of radiation whereas spatial differences are also linked to geographical altitudes and typical, summery large-scale weather conditions with the main wind direction from the SW.
Unravelling the North Alantic ‘nutrient stream’ variability
Authors: Carracedo Lidia I. , McDonagh Elaine , Sanders Richard , Mawji Edward , Torres-Valdés Sinhué , Baringer Molly , Mercier Herlé , Thierry Virginie
Published: March 2020

The Florida Current (FC), upstream extension of the Gulf Stream, is a very intense current (~32 Sv) confined to a 800-m depth narrow passage off the east coast of Florida. Associated with an intense poleward (subsurface maximum) transport of nutrients, this current has earned the name of North Atlantic ‘nutrient stream’. Since the biological sequestration of carbon (namely the Biological Carbon pump, BCP) is limited by the presence of nutrients in the upper ocean (euphotic zone), the FC can be seen as precursor of the nutrient induction process downstream feeding the subtropical gyre productivity. However, the relevance of this current is not only limited to its interplay with the subtropical gyre. The FC also comprises the bulk of the warm upper limb of the meridional overturning circulation reaching subpolar latitudes. Therefore, disentangling the range of intra-annual variability of the nutrient transport by the FC is crucial to better understand its linkage to and influence on the BCP magnitude and efficiency at higher latitudes. Based on a high-quality nutrient and velocity dataset from repeated hydrography between May 2015 and Oct 2018, we present an analysis of the nutrient transport by the FC in its 3 main water masses (the surface water, upper thermocline water and lower thermocline water). Our results show that the transport of inorganic nutrients is dominated by the upper and lower thermocline waters, whose transport-weighted nutrient concentration reaches a maximum in winter. Conversely, the transport of organic nutrients is dominated by the surface and upper thermocline waters, peaking in spring and autumn. Inorganic transport-weighted nutrient concentrations strongly correlate with volume transport. The correlation is positive in the surface water and the lower thermocline water (of South Atlantic origin), whereas it correlates negatively in the lower thermocline water (North Atlantic recirculated water). This indicates a southern remote source for the inorganic nutrient supply, which is mainly driven by advection. Organic nutrients, however, do not show a clear correlation with volume transport. Only the upper thermocline water shows a certain positive correlation, confirming the North Atlantic subtropical gyre as a main source of organic nutrients, ultimately driven not only -nor mainly- by circulation, but also by biological activity upstream.
What are we dating, volume diffusion or recrystallisation? Isotopic modelling and trace-element analysis as tools to interpret the high-temperature U-Pb thermochronometer in apatite and rutile
Authors: Mark Chris , Daly J. Stephen , Chew David , Cogné Nathan
Published: March 2020

The availability of high-temperature thermochronometers suitable for generation of continuous thermal histories at mid- to lower-crustal temperatures (i.e., ≥ 400 °C) is limited. Available thermochronometers include the recently developed apatite and rutile U-Pb thermochronometers ( ≤ 550 and 640 °C; Kooijman et al., 2010; Cochrane et al., 2014) and arguably the K-Ar system in white mica (sensitive to temperatures ≤ 500 °C. Recent work has focussed on micro-beam U-Pb analysis of apatite and rutile by sector-field and multi-collector LA-ICPMS to generate single-crystal U-Pb age profiles. Such profiles can be inverted to yield continuous thermal histories for high-temperature processes (e.g., Smye et al., 2018). However, both apatite and rutile can exhibit crystal growth and dissolution-reprecipitation reactions in the same temperature ranges at which measurable Pb diffusion occurs: neither behaves as a pure thermochronometer in all circumstances (e.g., Chambers and Kohn, 2012; Harlov et al., 2005). Thus, it is critical to develop protocols which unequivocally identify age profiles arising from volume diffusion.

Here, we present case studies from greenschist- to granulite-facies-grade metamorphic systems from the Eastern Alps and the Western Gneiss Region of Norway. We demonstrate the utility of trace-element analysis (Sr-Y-REE-Th-U) and isotopic forward modelling to discriminate age resetting arising from (re)crystallisation from diffusion. Both rutile and especially apatite routinely incorporate non-trivial amounts of common-Pb during crystallisation (as opposed to radiogenic Pb generated by in-situ radionuclide decay), rendering them discordant in U-Pb isotope space. This common-Pb must be corrected for during age calculation. However, common-Pb is isotopically distinct from radiogenic Pb but exhibits the same diffusion behaviour, so the predicted U-Pb isotopic distribution for a given crystal arising from a proposed thermal history can be estimated by isotopic forward modelling. Thus, common-Pb can be exploited to validate both the assumption of Pb-loss by volume diffusion, and the thermal history predicted by age profile inversion.

Chambers, J.A., & Kohn, M.J., Am. Mineral., 97, 543–555 (2012); Cochrane, R., et al., Geochim. Cosmochim. Acta, 127, 39–56, (2014); Harlov, D.E., et al., Contrib. Mineral. Petrol, 150, 268–286 (2005); Kooijman, E., et al., Earth Planet. Sci. Lett, 293, 321–330, (2010); Smye, A.J., et al., Chem. Geol., 494, 1–18 (2018).
Simulations of greenhouse gas emissions and soil organic carbon with ECOSSE for a rice field in Northern Italy
Authors: Kuhnert Matthias , Oliver Viktoria , Volante Andrea , Monaco Stefano , Teh Yit Arn , Smith Pete
Published: March 2020

Rice cultivation has high water consumption and emits large quantities of greenhouse gases. Therefore, rice fields provide great potential to mitigate GHG emissions by modifications to cultivation practices or external inputs. Previous studies showed differences for impacts of alternated wetting and drying (AWD) practices for above-ground and below-ground biomass, which might have long term impacts on soil organic carbon stocks. The objective of this study is to parameterise and evaluate the model ECOSSE for rice simulations based on data from an Italian rice test site where the effects of different water management practices and 12 common European cultivars, on yield and GHG emissions, were investigated. Special focus is on the differences of the impacts on the greenhouse gas emissions for AWD and continuous flooding (CF). The model is calibrated and tested for field measurements and is used for model experiments to explore climate change impacts and long-term effects. Long term carbon storage is of particular interest since it is a suitable mitigation strategy. As experiments showed different impacts of management practices on the below ground biomass, long term model experiments are used to estimate impacts on SOC of the different practices. The measurements also allow an analysis of the impacts of different cultivars and the uncertainty of model approaches using a single data set for calibration.
Sea-level and climate signatures recorded in the 1 Myr continental margin deposits from the Bohai Sea
Authors: Yao Zhengquan , Shi Xuefa , Liu Yanguang , Qiao Shuqing
Published: March 2020

Sediment accumulation in the continental margin is largely influenced by both sea-level fluctuations and climate changes during the Quaternary Period. However, the response of sediment accumulation to these changes at orbital timescale, remains poorly understood, mainly due to (i) the scarce of sedimentary records with high-resolution chronology and (ii) the difficulty of distinguishing the role of sea-level from climate signals. Here we present sediment color reflectance (c*), grain size and total organic carbon (TOC) data of core BH08 (212.4 m; ~1 Myr) recovered from the Bohai Sea, China. The chronology of core BH08 was constrained at orbital timescale by using magnetostratigraphy and astronomical tuning methods. Sedimentary facies analysis suggests that the core sequence is dominated by alternations of deltaic system and floodplain deposits. Principal components analysis on grain size data reveals two principal components (PCs), including PC1 (31–500 µm, coarse fraction) and PC2 (18–66 µm, fine fraction). Comparison of PC1, PC2, c* and TOC with sedimentary environments, we found that PC1 and c* corresponds well with cycles of deltaic and floodplain deposits at ~100/40-kyr cycles, while PC2 and TOC display ~20-kyr cycle, in addition to the ~100/40-kyr cycles. We interpret that PC1 and c* are mainly sea-level dependent, whereas PC2 and TOC are controlled by a combination of monsoonal climate and sea level. We suggest that Milankovitch-scale monsoon climate controlled the sediments supply to the Bohai Sea during the last 1 Myr, while the redistribution of sediments by marine process (e.g. tidal currents) seem to have obscured the monsoonal signal in the grain size proxy (e.g. PC1) which is sensitive to sea-level change. Our results provide an example of climate and sea-level influenced sediment accumulation in the shallow continental margin influenced by monsoonal climate in an icehouse world.