bluuebunny/crossref_metadata_2025 huggingface dataset:
Galactic Cosmic Ray Modulation at Mars and beyond measured with EDACs on Mars Express and Rosetta
Authors: Knusten Elise Wright , Witasse Olivier , Sanchez-Cano Beatriz , Lester Mark , Wimmer-Schweingruber Robert , Denis Michel , Godfrey James , Johnstone Andrew
Published: March 2021

Galactic Cosmic Rays (GCRs) are an intrinsic part of the heliospheric radiation environment, and an inevitable challenge to long-term space exploration. Here we show solar cycle induced GCR modulation at Mars in the period 2005-2020, along with GCR radial gradients, by utilising Mars Express and Rosetta engineering parameters compared to sunspot number time series. The engineering parameter used is called EDAC (Error Detection And Correction), a cumulative counter which is triggered by charged energetic particle causing memory errors in on-board computers. EDAC data provides a new way of gaining insight into the field of particle transport in the heliosphere, allowing us to circumvent the need for dedicated instrumentation as EDAC software is present on all spacecraft.

This data set can be used to capture variations of GCRs in both space and time, yielding the same qualitative information as ground-based neutron monitors. Our analysis of the Mars Express EDAC parameter reveals a strong solar cycle GCR modulation, yielding an anticorrelation coefficient of -0.5 at a time lag of ~5.5 months. By combining Mars Express with Rosetta data, we calculate a 5.3% increase in EDAC count rates per astronomical unit, attributed to a radial gradient in GCR fluxes in accordance with established literature.

The potential of engineering data for scientific purposes remains mostly unexplored. The results obtained from this work demonstrates, for the first time for heliophysics purposes, the usefulness of the EDAC engineering parameter, data mining and the utility of keeping missions operational for many years, providing complimentary data to nominal science instruments.
Interpretation of dust impact signals detected by Cassini at Saturn
Authors: Nouzak Libor , Pavlů Jiří , Vaverka Jakub , Šafránková Jana , Němeček Zdeněk , Píša David , Shen Mitchell H. , Sternovsky Zoltan , Ye Shengyi
Published: March 2021

The Cassini spacecraft spent more than 13 years in the dusty environment of Saturn. During this long period of investigations of the Saturn magnetosphere, the RPWS (Radio Plasma Wave Science) instrument recorded more than half a million spiky signatures. However, not all of them can be interpreted as dust impact signals because plasma structures like solitary waves can result in similar pulses.

We select the registered spike waveforms recorded by both dipole and monopole configurations of electric field antennas operated in 10 kHz or 80 kHz sampling rates at the distance of 0.2 Rs around the rings mid-plane. These waveforms were corrected using Cassini WBR (Wide Band Receiver) transfer function to obtain the correct shape of the signal. The signal polarity, amplitude, and timescales of different parts of the waveforms were quantitatively inspected according to the spacecraft potential, the density of the ambient plasma, the intensity of the Saturn’s magnetic field, and its orientation with respect to the spacecraft. The magnetic field orientation was also used for distinguishing between signals resulting from dust impacts and signals produced by solitary waves misinterpreted as dust impact signals.

The preliminary results of our study indicate similarities with previous laboratory studies of dust impact waveforms on the reduced model of Cassini bombarded with submicron-sized iron grains in external magnetic fields at the LASP facility of the University of Colorado. The polarity of the signals changes in accordance with a polarity of the spacecraft potential and pre-spike signals are also observed. The core of the paper is devoted to the relation between characteristics of dust impact signals and local plasma parameters and magnetic field intensity at the radial distance from 2 Rs to 60 Rs from Saturn surface.
Prediction of Size and Shape of Wetting Patterns Created by Inverted Open Plastic Bottles (IOPB)
Authors: Alrubaye Yasir , Yusuf Badronnisa , AL-Sammak Abdulla
Published: March 2021

Plastic bottles can be used in irrigation fields which introduces a sustainable low-cost alternative for irrigation methods. Until now, plastic bottles were used in small irrigation fields since there are limited scientific measurements of it is performance. The aim of this study is to predict the size and shape of the wetting patterns generated by inverted opened plastic bottles. Hydraulic simulations for 48 design cases of 12 different soil types and 4 sizes of subsurface source were accomplished using 2D-Hydrus. The simulation outputs were validated using experimental results. Multi regression analysis was used to identify the general formulae of the dependent variables of hydraulic conductivity, area of subsurface source, depth of the source, head of application, and time of application. The statistical analysis was formulated by the R-studio program. Results show that the maximum width and depth of wetting patterns occurred in sandy soil which were 34.1 and 96.8 cm, respectively. The minimum values were in silty clay with the width and depth of wetting patterns of 4.3 and 19 cm, respectively. The standard deviation of the width and depth were 9.02 and 22.58, respectively.  In conclusion, the soil type is a vital factor that impacts the flow in the soil profile and the size and shape of the wetting patterns. In addition, the size and depth of the subsurface source impact the size and location of the wetting patterns. The Head of the water in IOPB can be used to specify the size of the wetting patterns. The statistical model can be used to predict the size of the wetting patterns created by IOPBs accurately.
Combining thermo-kinematic and mechanical modelling on thrust faults - a quantitative approach to crustal deformation history: Case study from SE Tibet
Authors: Pitard Paul , Replumaz Anne , Doin Marie-Pierre , Thieulot Cédric , Chevalier Marie-Luce , Leloup Philippe Hervé , de Sigoyer Julia , Bai Mingkun , Haibing Li , Balvay Mélanie
Published: March 2021

Decoding the Tibetan plateau and its structural evolution has been a thorny issue for decades, triggering many controversial discussions between the proponents of the numerous key models. Numerical simulations of buoyancy forces associated with a thick crust and a low viscosity channel in the Tibetan crust predict continuous deformation, crustal uplift and thickening through an outward flow of partially molten middle/lower crust. Surface geological observations of fault systems, however, favor a model of localized deformation through the interaction between strike-slip and thrust faults. Here, we investigate the role of thrusting mechanisms involved in the plateau formation, which is essential in order to discuss these end-members competing models. We focus on the Muli thrust, a major Miocene thrust fault located at the eastern edge of the Tibetan Plateau, characterized by a pronounced topographic step of ~2000 m. We provide here an innovative quantitative approach combining thermo-kinematic modelling based on low-temperature thermochronology data, with conceptual 2-dimensional (2D) simulations of the crust’s mechanical behavior. Using the code PECUBE, we test different scenarios of rock cooling by forward modelling and inversion method in order to constrain the amount and timing of exhumation, as well as its simplified first-order crustal geometry. Given that low-temperature thermochronology data only provides the thermal history of the upper part of the crust (< 10 km), such thermo-kinematic modelling does not reveal any direct evidence of the potential implication of the lower crust. To overcome such limitations, we performed 2D mechanical modelling of the Muli thrust to constrain its mechanical behavior at the crustal scale to decipher its importance in the thickening of the plateau margin. We present here, how complementary numerical simulations based on in-situ geological observations on thrust faults, combined with thermochronology data, can be used to have a better understanding of the geological processes involved in the thickening of the Tibetan crust, and discuss both the strengths and weaknesses of such modelling.
Enhanced humidity in SW Iberia driven by the combination of insolation and ice-sheet forcing during MIS 13 interglacial
Authors: Oliveira Dulce , Desprat Stéphanie , Yin Qiuzhen , Rodrigues Teresa , Naughton Filipa , Trigo Ricardo , Su Qianqian , Grimalt Joan O. , Alonso-Garcia Montserrat , Voelker Antje H.L. , Abrantes Fátima , Sánchez Goñi Maria Fernanda
Published: March 2021

Marine Isotope Stage (MIS) 13, ~500 ky ago, represents a Quaternary interglacial of primary interest due to the unexpected enhancement of monsoon systems under a cool climate characterised by low atmospheric CO2 and larger ice volume than the present interglacial. Yet, key questions remain about its regional expression (intensity, climate variability, length) and underlying forcing factors. Here we examine the SW Iberian vegetation and terrestrial climate during MIS 13 directly compared with the sea surface temperatures using sediments from IODP Site U1385, and combine those terrestrial-marine profiles with climate-model experiments. We show for the first time that MIS 13 stands out for its large forest expansions with a reduced Mediterranean character alternating with muted forest contractions, indicating that this stage is marked by a cool-temperate climate regime with high levels of humidity. Results of our data-model approach reveal that that the dominant effect of MIS 13 insolation forcing on the regional vegetation and precipitation regime in SW Iberia is amplified by the relatively large extent of the ice-sheets in high northern latitudes. In qualitative agreement with the pollen-based evidence, model results show that ice-sheet forcing triggers an increase in the SW Iberian tree fraction along with both intensified winter and summer rainfall. We propose that the interactions between ice-sheets and major atmospheric circulation systems may have resulted in the persistent influence of the mid-latitude cells over the SW Iberian region, which led to intensified moisture availability and reduced seasonality, and, in turn, to a pronounced expansion of the temperate forest.
The role of fires for tundra-forest transition in northwest Siberia
Authors: Ezhova Ekaterina , Sizov Oleg , Tsymbarovich Petr , Soromotin Andrey , Prihod'ko Nikolay , Petäjä Tuukka , Zilitinkevich Sergey , Kulmala Markku , Bäck Jaana , Köster Kajar
Published: March 2021

Transition of arctic vegetation from tundra to shrubs and forest is an important process influencing global carbon budget. Transition is predicted due to warming and prolongation of the growing season but observations show that it is slower than expected. Fires are disturbances that could trigger a shift of biomes.

We studied the transition of dry tundra to forest and woodland in northwest Siberia for burned and background sites within the time interval of 60 years. We used meteorological data to estimate potential shifts in vegetation based on a bioclimatic model. To investigate fire and vegetation dynamics, we used historical and modern satellite imagery (Corona KH-4b, Landsat-5,7,8, Resurs-P, SPOT-6,7). We performed comparative analysis of vegetation using high-resolution satellite data from different years.

The growing season length increased by 20 days and the mean temperature of the growing season increased by 1°C making climatic conditions suitable for trees. We showed that ca 40% of the total study area experienced fires at least once during the last 60 years. Within this period, shift from dry tundra to tree-dominated vegetation occurred in 6-15% of the area in the non-disturbed sites compared to 40-85% of the area in the burned sites.
30 years of surface ozone measurements in Austria: long-term trends, attainment statistics, and changes in the temperature sensitivity of surface ozone production
Authors: Stähle Christoph , Mayer Monika , Schmidt Christian , Kult Jessica , Klaus Vinzent , Trimmel Heidelinde , Schreier Stefan , Karlicky Jan , Alexander Michael , Rieder Harald
Published: March 2021

As the production of ozone in surface air is determined by ambient temperature and by the prevalent chemical regime, a very different temperature dependence of ozone production emerges for nitrogen oxides (NOx) and volatile organic compounds (VOC) limited regions. In this study we evaluated the temperature sensitivity of ozone production for rural, suburban as well as urban sites in Austria on seasonal basis. The analysis is based on 30 years of observational data from Austrian monitoring networks for the time period 1990 – 2019. Reductions in precursor emissions as observed in 2020 in Austria due to the pandemic will be used to test the obtained results. Surface ozone, NOx, daily sums of global radiation and minimum daily temperature are used as covariates in our study. The observed NOx to VOC ratio at individual sites is variable over time due to changes in precursor emissions and/or the variability of meteorological parameters such as mixing layer height. At the site level we relate the temperature sensitivity of ozone production to the daily mean NOx mixing ratio and the daily minimum temperature. This information allows us to determine the impact of past/future temperature changes on surface ozone abundance in the context of reductions of NOx emissions and changing methane backgrounds.
Algorithms for constructing structural surfaces by geophysical data based on neural networks
Authors: Shklyaruk Alexey , Kuznetsov Kirill , Arutyunyan David , Lygin Ivan
Published: March 2021

At the stage of small and medium-scale geological and geophysical studies, in addition to seismic exploration, methods of potential fields (gravimetry and magnetometry) are usually actively used. These methods, in contrast to the profile seismic observations, taking into account modern satellite and aviation technologies, provide a high-quality areal density and magnetic characteristics of the study area. The main tasks of modern gravimetry and magnetometry include the task of constructing areal models, contrasting in density and magnetization of surfaces. Among a large number of algorithmic solutions, the most effective are methods using an integrated approach, in which seismic data on the morphology of reflecting horizon is used as a reference.

Reconstruction of the structural surface morphology by geophysical data can be considered as the problem of finding the relationship between the input information (potential fields, geophysical data, and available a priori information) and the desired surface. To assess the dependence, it is proposed to use the reference plots on which both input and output data are presented. Currently, one of the trends in solving such problems is methods based on neural networks. Neural networks can be of various configurations (feedforward networks, radial-basis function networks, backpropagation networks, convolutional networks, etc.), have a different number of layers and neurons.

In this research, we consider the test and real-world example. A site with a known position of the sedimentary cover bottom is considered as a test model. To verify and compare the algorithms, the gravity and magnetic effects of the layer are calculated. The gravity and magnetic fields were supplied to the input to the algorithms for constructing regression dependence and training the neural network. An incomplete model of the sedimentary cover was supplied to the input for training neural networks. The task was to restore the missing part. The parameter of the standard deviation of the original and reconstructed model was less than 2% for all types of neural networks.

As a real model, a site was considered where basement cover is only partially available. It was obtained as a result of seismic interpretation. All available geological and geophysical data were used to reconstruct the horizon. Models obtained using reconstruction algorithms can be additional information for further detailed description of the geological structure.

It should be noted that since neural networks help to find complex functional relationships between field parameters and attributes of the studied environment, they could be used in the tasks of complex interpretation of geological and geophysical data.
Effect of precipitation and stream discharge on the source composition of stream water
Authors: Zhang Zhi-Yuan , Schmidt Christian , Fleckenstein Jan
Published: March 2021

The exchange of water between streams and groundwater plays an important role for hydrologic and biogeochemical processes. Along a stream the composition of stream water is modified by sequential losses of stream water with the current in-stream chemical signature to the subsurface and gains of water with another signature from the subsurface. This process has been termed hydrologic turnover. To date, most studies on hydrologic turnover have been focused on small stream networks. Moreover, the influence of hydrologic conditions on hydrologic turnover has not been systematically investigated. Taking the lower Selke River in central Germany as an example, we evaluated the evolution of stream-groundwater exchange and the source composition of stream water under different precipitation and stream discharge conditions, based on a coupled stream-groundwater model built in MODFLOW using the Streamflow-routing (SFR1) package. The results show that the stream reaches could be classified into three types: permanently gaining reaches, permanently losing reaches, and transitional reaches. Transitional reaches range from losing condition at higher stream discharge or lower precipitation to gaining condition at lower stream discharge or higher precipitation. In the lower Selke River with a length of 30 km, transitional reaches account for nearly 30% of the total river length in the studied period from 2011 to 2018. Regardless of dry or wet hydrologic condition, nearly 80% of the total groundwater contribution to stream discharge at the catchment outlet were generated over 20% of the total river length. This indicates diffuse groundwater pollution such as from agricultural nitrate may enter the stream network predominantly at a few distinct reaches. Our analysis can help to prioritize areas in a catchment where reduction of diffuse groundwater pollution would have the highest impact on improving stream water quality.
In situ observation of three-dimensional anisotropies and scalings of space plasma turbulence at kinetic scales
Authors: Wang Tieyan , He Jiansen , Alexandrova Olga , Dunlop Malcolm , Perrone Denise
Published: March 2021

The energy distribution at wave number space is known to be anisotropic in space plasmas. At kinetic scales, the standard Kinetic Alfven Wave model predicts anisotropy scaling of kpar ∝ kperp(1/3), whereas the latest models considering the intermittency, or tearing instabilities, predict scalings such as kpar ∝ kperp(2/3) and kpar ∝ kperp(3/3). Recent numerical simulations also payed considerable attention to this issue. Based on a unified analysis of five-point structure functions of the turbulence in three kinetic simulations, Cerri et al. 2019 obtained a converging result of lpar ∝ lperp(3/3). To enrich our knowledge of the anisotropic scaling relation from an observational point of view, we conducted a statistical survey for the turbulence measured by MMS in the magnetosheath. For the 349 intervals with burst mode data, abundant evidence of 3D anisotropy at the sub-proton scale (1-100 km) is revealed by five-point second order structure functions. In particular, the eddies are mostly elongated along background magnetic field B0 and shortened in the two perpendicular directions. The ratio between eddies’ parallel and perpendicular lengths features a trend of rise then fall toward small scales, whereas the anisotropy in the perpendicular plane appears scale invariant. Moreover, over 30% of the events exhibit scaling relations close to lpar ∝ lperp(2/3). In order to explain such signature, additional factors such as intermittency caused by different coherent structures may be required in addition to the critical balance premise.
Predicting geo-effectiveness of CMEs using a novel 3D CME model FRi3D integrated into EUHFORIA 
Authors: Poedts Stefaan , Maharana Anwesha , Scolini Camilla , Isavnin Alexey
Published: March 2021

Previous studies of Coronal Mass Ejections (CMEs) have shown the importance of understanding their geometrical structure and internal magnetic field configuration for improving forecasting at Earth. The precise prediction of the CME shock and the magnetic cloud arrival time, their magnetic field strength and the orientation upon impact at Earth is still challenging and relies on solar wind and CME evolution models and precise input parameters. In order to understand the propagation of CMEs in the interplanetary medium, we need to understand their interaction with the complex features in the magnetized background solar wind which deforms, deflects and erodes the CMEs and determines their geo-effectiveness. Hence, it is important to model the internal magnetic flux-rope structure in the CMEs as they interact with CIRs/SIRs, other CMEs and solar transients in the heliosphere. The spheromak model (Verbeke et al. 2019) in the heliospheric wind and CME evolution simulation EUHFORIA (Pomoell and Poedts, 2018), fits well with the data near the CME nose close to its axis but fails to predict the magnetic field in CME legs when these impact Earth (Scolini et al. 2019). Therefore, we implemented the FRi3D stretched flux-rope CME model (Isavnin, 2016) in EUHFORIA to model a more realistic CME geometry. Fri3D captures the three-dimensional magnetic field structure with parameters like skewing, pancaking and flattening that quantify deformations experienced by an interplanetary CME. We perform test runs of real CME events and validate the ability of FRi3D coupled with EUHFORIA in predicting the CME geo-effectiveness. We have modeled two real events with FRi3D. First, a CME event on 12 July 2012 which was a head-on encounter at Earth. Second, the flank CME encounter of 14 June 2012 which did not leave any magnetic field signature at Earth when modeled with Spheromak. We compare our results with the results from non-magnetized cone simulations and magnetized simulations employing the spheromak flux-rope model. We further discuss how constraining observational parameters using the stretched flux rope CME geometry in FRi3D affects the prediction of the magnetic field strength in our simulations, highlighting improvements and discussing future perspective.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0)
Airborne Atmospheric Measurements with the Max Planck CloudKites
Authors: Schröder Marcel , Nordsiek Freja , Schlenczek Oliver , Ibañez Landeta Antonio , Güttler Johannes , Bagheri Gholamhossein , Bodenschatz Eberhard
Published: March 2021

To investigate cloud microphysics and turbulence in clouds and in the atmospheric boundary layer, we specially developed airborne platforms, one Max-Planck-CloudKite + (MPCK+) and two mini-Max-Planck-CloudKites (mini-MPCK). They are deployed aboard balloon-kite hybrids conducting in situ measurements of meteorological and cloud microphysical properties with high spatial and temporal resolution. During the EUREC4A-ATOMIC field campaign in the Caribbean January-February 2020, the MPCK+ and one mini-MPCK sampled clouds aboard a 250 m3 aerostat launched from the R.V. Maria S. Merian where both instruments were operated between MSL and 1500m MSL. In addition, one mini-MPCK profiled the atmosphere between MSL and 1000 m MSL aboard a 74 m3 aerostat launched from the R.V. Meteor. In total, we acquired 145 h of flight-data on RV Maria S. Merian and 52 h of flight-data on RV Meteor. For the MPCK+, this included 5 hr of Particle Image Velocimetry data and 3 hr of inline holography data inside clouds and near the cloud edges. We present in situ data measured by the MPCKs during the EUREC4A-ATOMIC field campaign and report on preliminary assessment of turbulence features.
Quantification of the total methane emission from valley artificial reservoir – combination of measurements and process-based modelling
Authors: Lomov Viktor , Stepanenko Victor , Grechushnikova Maria , Repina Irina
Published: March 2021

In a context of global warming an important objective is an estimation of green-house gases fluxes into the atmosphere from different sources. Methane is a crucial green-house gas in the atmosphere with specific global warming potential 28 times larger than that of carbon dioxide. Our research is focused on estimation of methane emission from artificial Mozhaysk valley reservoir, located in Russia, Moscow region. The main goal of the study is to quantify the methane emission by two approaches – measuring the fluxes in situ on the reservoir and modelling the methane emission by 1D hydrodynamic and biogeochemical model. Combination of these methods provides more reliable result compared to using them separately. We expect, that firstly tested on Mozhaysk reservoir this approach can be applied to other artificial reservoirs, which is especially important for estimating carbon footprint of hydro energetics. The measurements on Mozhaysk reservoir have been carried since 2015. The patterns of spatial-temporal variability of methane flux are demonstrated. The highest values of methane emission during open-water period are typically observed in the end of summer, at the initiation of autumnal convective mixing. In this period, methane flux into the atmosphere can reach 350 – 390 mgC-CH4*m-2*d-1. High values of methane flux, up to 400 mgC-CH4*m-2*d-1, were observed after the storm events. As to spatial flux distribution, the highest values of methane emission were observed in the middle part of the reservoir and in shallow areas inhabited by macrophytes plants. The 1D hydrodynamic and biogeochemical model LAKE simulated high variability of methane flux into the atmosphere in the annual cycle. According to modeling results, the main pathway of methane into the atmosphere is ebullition, constituting more than 95% in total methane evasion into the atmosphere. The highest values of CH4 flux according to model results take place in the beginning of spring period, after the ice-off, and during the mixing events. Modelling results for methane emission demonstrate satisfactory agreement to in situ measurements – the average annual methane emission during 5 years is 430 tons of C-CH4 per year according to observation, and 380 tons of C-CH4 per year in model simulations.

The work is supported by Russia`s President Council of Grants for Young Scientists, grant No. MD 1850.2020.5.
Deep-sea panoramas: Progress and remaining challenges in late Miocene stratigraphy and climate
Authors: Drury Anna Joy , Westerhold Thomas , Hodell David A. , Lyle Mitchell , John Cédric M. , Shevenell Amelia E. , Röhl Ursula , Wilkens Roy
Published: March 2021

During the late Miocene, meridional sea surface temperature gradients, deep ocean circulation patterns, and continental configurations evolved to a state similar to modern day. Deep-sea benthic foraminiferal stable oxygen (δ18O) and carbon (δ13C) isotope stratigraphy remains a fundamental tool for providing accurate chronologies and global correlations, both of which can be used to assess late Miocene climate dynamics. Until recently, late Miocene benthic δ18O and δ13C stratigraphies remained poorly constrained, due to relatively poor global high-resolution data coverage.

Here, I present ongoing work that uses high-resolution deep-sea foraminiferal stable isotope records to improve late Miocene (chrono)stratigraphy. Although challenges remain, the coverage of late Miocene benthic δ18O and δ13C stratigraphies has drastically improved in recent years, with high-resolution records now available across the Atlantic and Pacific Oceans. The recovery of these deep-sea records, including the first astronomically tuned, deep-sea integrated magneto-chemostratigraphy, has also helped to improve the late Miocene geological timescale. Finally, I will briefly touch upon how our understanding of late Miocene climate evolution has improved, based on the high-resolution deep-sea archives that are now available.
Analysis of Subdaily Meteorological Measurements by Louis Morin in the Late Maunder Minimum 1665 – 1709 in Paris
Authors: Pliemon Thomas , Foelsche Ulrich , Rohr Christian , Pfister Christian
Published: March 2021

Based on copies of the original data (source: Oeschger Center for Climate Change Research) we perform climate reconstructions for Paris between 1665 - 1709. The focus lies on the following meteorological variables: temperature, cloudiness, direction of movement of the clouds, precipitation and humidity. Apart from humidity, these meteorological variables were measured three times a day over the entire period from Louis Morin. Temperature and humidity were measured with instruments, whereas cloud cover, direction of movement of the clouds and precipitation were measured in a descriptive manner. In addition to the quantitative temperature measurements, conclusions about synoptic air movements over Europe are possible due to the additional meteorological variables. The Late Maunder Minimum is characterised by cold winters and moderate summers. Winter is characterised by a lower frequency of westerly direction of movement of the clouds. This reduction of advection from the ocean leads to cooling in Paris and also to less precipitation in winter. This can be seen very strongly between the last decade of the 17th century (cold) and the first decade of the 18th century (warm). A lower frequency of westerly direction of movement of the clouds can also be seen in summer, but the influence is stronger in winter than in summer. However, this reduction leads to moderate/warm temperatures in summer. So unusually cold winters in the Late Maunder Minimum can be attributed to a lower frequency of westerly direction of movement of the clouds.
Conditional spatio-temporal random crop for weak labeled SAR datasets
Authors: Asaro Francesco , Murdaca Gianluca , Prati Claudio Maria
Published: March 2021

This work presents a methodology to improve supervised learning of segmentation tasks for convolutional architectures in unbalanced and weak labeled synthetic aperture radar (SAR) dataset scenarios, which characterize the Earth Observation (EO) domain. The presented methodology exploits multitemporality and stochasticity to regularize training by reducing overfitting and thus improving validation and test performances.

Traditional precisely annotated datasets are made of patches extracted from a set of image-label pairs, often in a deterministic fashion. Through a set of experiments, we show that this approach is sub-optimal when using weak labels since it leads to early overfitting, mainly because weak labels only mark the simplest features of the target class.

The presented methodology builds up the dataset from a multitemporal stack of images aligned with the weakly labeled ground truth and samples the patches both in time and space. The patches are selected only if a given condition of the positive class frequency is met. We show learning improvements against the traditional methodology by applying our strategy to a benchmark task, which consists of training a typical deep convolutional network, Unet (Ronneberger et al, 2015), for the segmentation of water surfaces in SAR images.

The dataset sources are Sentinel-1, calibrated sigma zero, VV-VH polarized, single-look, intensity images for the inputs, and the Copernicus’s “Water and Wetness High Resolution Layer” for the weak labels. To avoid spatial autocorrelation phenomena, the training set covers the Low Countries (Belgium, the Netherlands, and Luxembourg), while the validation and test-set span the Padana plain area (Italy). The training dataset is built up according to the methodology, while the validation and test datasets are defined in a deterministic fashion as usual.

We show the beneficial effects of multitemporality, stochasticity, and conditional selection in three different sets of experiments, as well as in a combined one. In particular, we observe performance improvements in terms of the F-1 score, which increases together with the degree of multitemporality (number of images in the stack), as well as when stochasticity and conditional rules that compensate the under-representation of the positive class are added. Furthermore, we show that in the specific framework of SAR data, the introduction of multitemporality improves the learned representation of the speckle, thus implicitly optimizing the Unet for both the filtering and segmentation tasks. We prove this by comparing the number of looks of the input patch to that of the patch reconstructed before the classification layer.

Overall, in this framework, we show that solely using the presented training strategy, the classifier's performance improves up to 5% in terms of the F-1 score.
Prototype products for climate change adaption in German coastal regions
Authors: Ehlers Birte-Marie , Janssen Frank , Su Jian
Published: March 2021

The “German Strategy for Adaption to Climate Change” (DAS) is the political framework to climate change adaption in Germany. The newly established DAS basic service “Climate and Water” will provide monitoring and projection data to evaluate requirements for climate change adaption. Various products covering the German water bodies (coastal and inland) and its response to climate change will be generated and frequently updated by a cooperation of four German federal agencies. The products will be tailored to a variety of stakeholders needs.

Within this framework, the Federal Maritime and Hydrographic Agency (BSH) will provide products based on an ensemble of climate projections for the German coast which will be created in cooperation with different research institutes and authorities, e.g. the Danish Meteorological Institute (DMI).

Data from a DMI climate projection run based on the HIROMB-BOOS model (HBM) with a meteorological forcing from DMI-HIRHAM5 (one of the RCMs in EURO-CORDEX ensemble) and for the RCP 8.5 scenarios has been analysed in view of different oceanographic parameters such as sea level, sea surface temperature, salinity, currents and ice. This data set includes the historical periods 1981-2010 and the RCP 8.5 periods 2041-2070 and 2071-2100. Therefore, it provides an expedient basis to develop prototype products regarding climate change adaption at the German coasts for customers of the DAS basic service “Climate and Water”. The initial prototype products are presented and discussed in regards to the sufficiency to evaluate requirements for climate change adaption.
High-frequency ground-motion variability for rough-fault ruptures  
Authors: Vyas Jagdish Chandra , Galis Martin , Mai Paul Martin
Published: March 2021

Geological observations show variations in fault-surface topography not only at large scale (segmentation) but also at small scale (roughness). These geometrical complexities strongly affect the stress distribution and frictional strength of the fault, and therefore control the earthquake rupture process and resulting ground-shaking. Previous studies examined fault-segmentation effects on ground-shaking, but our understanding of fault-roughness effects on seismic wavefield radiation and earthquake ground-motion is still limited.  

In this study we examine the effects of fault roughness on ground-shaking variability as a function of distance based on 3D dynamic rupture simulations. We consider linear slip-weakening friction, variations of fault-roughness parametrizations, and alternative nucleation positions (unilateral and bilateral ruptures). We use generalized finite difference method to compute synthetic waveforms (max. resolved frequency 5.75 Hz) at numerous surface sites  to carry out statistical analysis.  

Our simulations reveal that ground-motion variability from unilateral ruptures is almost independent of  distance from the fault, with comparable or higher values than estimates from ground-motion prediction equations (e.g., Boore and Atkinson, 2008; Campbell and Bozornia, 2008). However, ground-motion variability from bilateral ruptures decreases with increasing distance, in contrast to previous studies (e.g., Imtiaz et. al., 2015) who observe an increasing trend with distance. Ground-shaking variability from unilateral ruptures is higher than for bilateral ruptures, a feature due to intricate seismic radiation patterns related to fault roughness and hypocenter location. Moreover, ground-shaking variability for rougher faults is lower than for smoother faults. As fault roughness increases the difference in ground-shaking variabilities between unilateral and bilateral ruptures increases. In summary, our simulations help develop a fundamental understanding of ground-motion variability at high frequencies (~ 6 Hz) due small-scale geometrical fault-surface variations.
The effect of road networks on the forest wildfires ‘size
Authors: Mohammadi Zohreh , Lohmander Peter , Kašpar Jan , Marušák Robert
Published: March 2021

Forest roads are crucial to forest conservation. They can be perfect barriers against forest wildfires if they maintained appropriately and firefighting equipment were provided. This paper discusses the effect of forest roads in context of forest transportation and fire fighting in Czech Republic forestry. The results prove that, the wildfire sizes are reduced if the fire brigade can reach the fires more rapidly.  In other words, the wildfire sizes were evaluated from a function of the distances to roads. Increasing road density can decrease wildfire size. Enhancement of the road network can decrease the future wildfire problems as attack times strongly effects on wildfire sizes. This motivates the location of some firefighting stations close to the forest areas. Furthermore, the importance of road density, road quality and other infrastructure to attack time and efficiency, such as bridges and water reservoirs, may be enhanced. In case forest management methods, infrastructure and the capacities of fire brigades are not updated to the new climate, larger areas destroyed by wildfires can be predicted.

Keywords: attack time, forest roads, forest management, forest wildfires, Czech Republic forestry.
Nanoplastics in the Dutch Wadden Sea
Authors: Materić Dušan , Holzinger Rupert , Niemann Helge
Published: March 2021

Plastic pollution in the marine environment has been identified as a global problem;  different polymer types and sizes have been detected across all marine regions, from sea ice to the equator and the surface to the deep sea. Previous works show that smaller size classes of plastic debris are more abundant, e.g. fragments <100 µm account for 86% of all plastics pieces in the southern North Sea. However, the large unknown is to quantify the fraction of marine plastics debris below the size-detection limit of commonly used techniques (e.g. µFTIR spectroscopy, LOD >10 µm), such as ultrafine, nanometre-sized plastic particles - nanoplastics. In this work, we used a novel Thermal Desorption – Proton Transfer Reaction – Mass Spectrometry (TD-PTR-MS) method suitable for chemical detection and identification of plastics in the nm range and analysed samples from the Wadden Sea, Netherlands. We tested different sample preparation strategies including direct measurement of seawater and pre-concentration using a cascade filtration over quartz fibre filters of different average mesh sizes (>2.7, >1.2, >0.7, >0.3 µm).

Our results show the presence of Polystyrene (PS) and Polyethylene terephthalate (PET) in the fraction of small microplastics (e.g. <2.7 µm) and nanoplastics (<1 µm). The average mass concentration of our semiquantitative (highly conservative) measurements for PS nanoplastics was 0.8 µg/L indicating a substantial contribution of nanoplastics to the Wadden Sea’s total plastic’s budget. For example, considering the reported average of 27.2 microplastics in m3 of southern North Sea surface water, an average size of 100 µm, spherical shape and the density of 1 g/cm3 we calculate a tentative nanoplastics mass contribution of 38% compare to microplastics. Furthermore, we observed dynamic concentration changes of small microplastics and nanoplastics over time and water depth, and we are currently investigating if these are related to tidal currents, which are a strong forcing factor in the Wadden Sea.
Development of surface roughness length and drag parameterizations over deep seas
Authors: Rabaneda Alberto
Published: March 2021

Many formulations to determine the sea surface roughness length (z0) have been proposed in the past. The well-known Charnock’s equation is applied in most of the previous research. In this study, a different point of view is adopted to develop a new formulation. The starting point is an alternative method for surface roughness length calculation, i.e., the Lettau’s method. This method has already been validated onshore in the presence of obstacles over a domain; for obstacles with a defined cross-section perpendicular to the wind direction plane. Over deep waters, it is expected to find only one type of obstacle, i.e., consecutive waves forming straight lines. Different wave systems and the presence of swell add complexity to determine the sea surface profile. Hence, the adaptation of Lettau’s method seems reasonable, but the demonstrated dependency of z0 to wave age cannot be neglected.

Wind-generated waves result from a kinetic energy transfer between the atmosphere and the sea surface. However this physical process is not represented in the well-known logarithmic law. While this effect can be neglected onshore, in offshore environments it can be significant, as 20% of the time z0 is found to be over the expected range. Therefore, a kinetic energy transfer correction is included into an offshore logarithmic law. With an aerodynamic z0, achieved by the adaptation of the Lettau’s equation, and the new offshore logarithmic law, an empirical method for the kinetic energy transfer correction is proposed.
Multidecadal internal variability role in estimating sea level acceleration: Fremantle case study
Authors: Agha Karimi Armin
Published: March 2021

Low frequency internal signals bring challenges to signify the role of anthropogenic factors in sea level rise and to attain a certain accuracy in trend and acceleration estimations; thus, modelling these signals is crucial. Due to both spatially and temporally poor coverage of the relevant data sets, identification of internal variability patterns is not straightforward. In this study, the identification and role of low frequency internal variability (decadal and multidecadal) in sea level change of Fremantle tide gauge station is analysed using two climate indices, Pacific Decadal Oscillation (PDO) and Tripole Interdecadal Pacific Oscillation (TPO). The wavelet transform is applied on the sea level and climate indices time series for this purpose. It is shown that the multidecadal sea level variability is anticorrelated with corresponding components of climate indices in the Pacific Ocean, with correlation coefficients of -0.9 and -0.76 for TPO and PDO, respectively. The correlations are comparatively low in decadal time scale, by correlation coefficient of approximately -0.5 for both indices. To estimate trend and acceleration in Fremantle, three trajectory models are tested. The first model is a simple second-degree polynomial comprising trend and acceleration terms. Low passed PDO, representing decadal and interdecadal variabilities in Pacific Ocean, is added to the first model to form the second model. For the third model, decomposed signals of decadal and multidecadal variability of TPO are added to the first model. For all trajectory models, different noise models are tried and according to Akaike and Bayesian information criteria, the best noise model is AR(5). In overall, TPO explains the low frequency internal variability better than PDO for sea level variation in Fremantle. Although the estimated trends does not change significantly for the three models, the estimated acceleration is substantially different. The accelerations estimated from the first and second models are statistically insignificant, 0.006 ± 0.012 mm.yr-2 and 0.01 ± 0.01 mm.yr-2 respectively, while this figure for the third model is 0.018 ± 0.01 mm.yr-2. The outcome exemplifies the importance of modelling low frequency internal variability in acceleration estimations for sea level rise in regional scale.
Geo.KW, a coupled hydrothermal and infrastructure model at urban scale
Authors: Schramm Thilo , Böttcher Fabian , Pauw Viktoria , Odersky Leonhard , Halilovic Smajil , Davis Kyle
Published: March 2021

To reduce anthropogenic climate change, our energy demand needs to be met by renewable energies, wherever possible. So far, only a minor part of heating and cooling is met by such sources. Shallow geothermal energy, powered by green electricity, can close this gap at a high level of efficiency, while reducing intermittency problems current renewables have. As there are various competing uses of the underground in urban environments, e.g. drinking water protection and infrastructure, local authorities are more and more restrictive in granting licenses for new shallow geothermal systems.

In the project Geo.KW we created a coupling approach, which combines hydrothermal and infrastructure modeling to efficiently position shallow geothermal systems between existing uses and other conflicting groundwater usage, optimized by economical and ecological constraints. This should act as a planning tool for water authorities and policymakers.

We are using PFLOTRAN, a finite volume Darcy-Richards model as our flow and heat transport model.
The energy infrastructure optimization is done with urbs, a linear optimization model for distributed energy systems.
For our iterative coupling, we are using preCICE, a multi-physics coupling library, which facilitates fully parallel peer-to-peer exchange between these modeling domains.

The city of Munich is the pilot-region for the implementation of our tool, supported by local government and water authorities. The size and complexity of the model makes it necessary to run the optimization approach on a supercomputer, i.e. the SuperMUC-NG of the Leibniz Supercomputing Centre. Even there, the model needs to be partitioned for the energy infrastructure optimization to be feasible.