bluuebunny/crossref_metadata_2025 huggingface dataset:
Tradeoffs in water extremes: combining hydraulic and economic modeling to assess the economic and financial viability of de Lastras de Cuéllar Dam, Spain
Authors: González López Héctor , Pérez-Blanco C. Dionisio , Gil-García Laura
Published: March 2020

Abstract

Growing population and water demand (e.g for irrigation, water supply) and the vagaries of climate, now aggravated due to climate change, intensify societal exposure to water extremes and the economic and environmental impact of floods and droughts in Mediterranean basins. The Douro River Basin Authority (DRBA) in central Spain is assessing whether to build a dam in the Cega Catchment (Spain) with the twofold objective of substituting irrigation withdrawals from overallocated aquifers with relatively more abundant surface water, and of mitigating flood damage in the middle and lower stretches of the Cega River -the only non-regulated river in the DRB. This paper assesses and compares the costs of two alternative adaptation strategies to growing scarcity and more frequent and intense water extremes, namely dam construction v. the statu quo strategy where no dam is built. To this end, a Positive Multi-Attribute Utility Programing (PMAUP) that mimics farmer´s behavior and responses is used to assess the impacts on agricultural employment and gross value added of selected strategies in the irrigation sector; while the hydrologic model River Analysis System (HEC-RAS) is used to simulate the economic impact of flood events considering standard return periods, based on the global flood depth-damage functions developed by Huizinga et al. (2017). Both models are used to run 900 simulations reproducing alternative socioeconomic and climatic/hydrologic scenarios. The result is a database representing multiple plausible futures, which is used to identify vulnerabilities of proposed adaptation strategies and potential tradeoffs between responses -notably those referring to the design and operation rules of the dam, and the potential impact of floods and droughts. This methodology and the resultant database are combined with experts’ knowledge through robust decision-making tools to identify the preferred (i.e. robust) adaptation policy.
Realizing Maximum Transparency of Oceanographic Data Processing and Data Quality Control for Different End-User Communities
Authors: Köllner Manuela , Wilms Mayumi , Schulz Anne-Christin , Moritz Martin , Latarius Katrin , Klein Holger , Herklotz Kai , Jochumsen Kerstin
Published: March 2020

Reliable data are the basis for successful research and scientific publishing. Open data policies assure the availability of publicly financed field measurements to the public, thus to all interested scientists. However, the variety of data sources and the availability or lack of detailed metadata cause a huge effort for each scientist to decide if the data are usable for their own research topic or not. Data end-user communities have different requirements in metadata details and data handling during data processing. For data providing institutes or agencies, these needs are essential to know, if they want to reach a wide range of end-user communities.

The Federal Maritime and Hydrographic Agency (BSH, Bundesamt für Seeschifffahrt und Hydrographie, Hamburg, Germany) is collecting a large variety of field data in physical and chemical oceanography, regionally focused on the North Sea, Baltic Sea, and North Atlantic. Data types vary from vertical profiles, time-series, underway measurements as well as real-time or delayed-mode from moored or ship-based instruments. Along other oceanographic data, the BSH provides all physical data via the German Oceanographic Data Center (DOD). It is crucial to aim for a maximum in reliability of the published data to enhance the usage especially in the scientific community.

Here, we present our newly established data processing and quality control procedures using agile project management and workflow techniques, and outline their implementation into metadata and accompanied documentation. To enhance the transparency of data quality control, we will apply a detailed quality flag along with the common data quality flag. This detailed quality flag, established by Mayumi Wilms within the research project RAVE Offshore service (research at alpha ventus) enables data end-users to review the result of several individual quality control checks done during processing and thus to identify easily if the data are usable for their research.
Temperature monitoring in mountain regions using reanalyses: Lessons from the Alps
Authors: Scherrer Simon C. , Kotlarski Sven
Published: March 2020

The monitoring of near-surface temperature is a fundamental task of climatology that remains especially challenging in mountain regions. Here we assess the regional monitoring capabilities of modern reanalysis products in the well-monitored northern Swiss Alps during the last 20 to almost 60 years. Monthly and seasonal 2 m air temperature (T2m) anomalies of the global ERA5 and the three regional reanalysis products HARMONIE, MESCAN-SURFEX and COSMO-REA6 are evaluated against high quality in situ observational data for a low elevation (foothills) mean, and a high elevation (Alpine) mean. All reanalysis products show a good year-round performance for the foothills with the global reanalysis ERA5 showing the best overall performance. The high-resolution regional reanalysis COSMO-REA6 clearly performs best for the Alpine mean, especially in winter. Most reanalysis data sets show deficiencies at high elevations in winter and considerably overestimate recent T2m trends in winter. This stresses the fact that even in the most recent decades utmost care is required when using reanalysis data for near-surface temperature trend assessments in mountain regions. Our results indicate that a high-resolution model topography is an important prerequisite for an adequate monitoring of winter T2m using reanalysis data at high elevations in the Alps. Assimilating T2m remains challenging in highly complex terrain. The remaining shortcomings of modern reanalyses also highlight the continued need for a reliable and dense in situ observational monitoring network in mountain regions.

 
Chemical characterization of submicrometer organic aerosol particles from the Amazon rainforest with high-resolution mass spectrometry
Authors: Leppla Denis , Kremper Leslie , Zannoni Nora , Praß Maria , Ditas Florian , Holanda Bruna , Pöhlker Christopher , Williams Jonathan , Sá Marta , Wolff Stefan , Solci Maria Christina , Hoffmann Thorsten
Published: March 2020

The Amazon Rainforest is one of the most important pristine ecosystems for atmospheric chemistry and biodiversity. This region allows the study of organic aerosol particles as well as their nucleation into clouds. However, the rainforest is subject to constant change due to human influences. Thus, it is essential to acquire climate data of trace gases and aerosols over the next decades for a better understanding of the atmospheric oxidant cycle. Therefore, the research site Amazon Tall Tower Observatory (ATTO) was established in the central Amazon Basin to perform long-term measurements under almost natural conditions.

Biogenic emissions of volatile organic compounds (VOCs) mainly consist of isoprene and terpenes. They are responsible for the production of a large fraction of atmospheric particulate matter. Isoprene represents the largest source of non-methane VOCs in the atmosphere and is primarily emitted from vegetation. Its global emissions were estimated in the magnitude of about 500 ‒ 600 Tg per year. Originally, the isoprene photooxidation was not expected to contribute to the secondary organic aerosol (SOA) budget, due to the high volatility of resulting oxidation products. However, several studies have proven evidence for the importance of isoprene SOA formation. Based on the two double bonds, isoprene is highly reactive towards atmospheric oxidants like OH and NO radicals. The subsequent reactive uptake on acidic particles is strongly dependent on the NO concentration. Therefore, anthropogenic sources have a substantial impact on the isoprene photooxidation.

The chemical composition of atmospheric aerosols in the rainforest highly depends on the current season, since the Amazon basin exhibits huge variations of gaseous and particulate matter with clean air conditions during the wet season and polluted conditions during the dry season, due to biomass burning events. For a comprehensive statement, it is necessary to perform field measurements under both conditions to study the isoprene and terpene SOA contribution. For that reason, filter samples were collected at ATTO at different heights to analyze the aerosol composition emitted both from local and regional sources.

High-resolution mass spectrometry combined with data mining techniques will help to link characteristic SOA compounds to certain climate conditions in order to get insights into the Amazon aerosol life cycle.
Comparison of isotopic signatures in speleothem records and model simulations for the past millennium
Authors: Buehler Janica , Kirschner Moritz , Roesch Carla , Holloway Max D. , Sime Louise , Rehfeld Kira
Published: March 2020

Global changes in climate, especially in mean temperature, receive increasing public as well as scientific attention under the current warming trend. However, the probability of extreme events and their societal impact is also governed by changes in climate variability. Improving the understanding of changes in both and their relationship is crucial for projecting reliable climate change scenarios. Model-data comparisons between general circulation models and speleothem paleoclimate archives, with δ18O as a temperature and precipitation proxy, have been suggested to test and validate the capability of different climate models.

Speleothems are precisely date-able and provide well preserved (semi-)continuous climate signals in the lower and mid-latitudes, providing a suitable archive to assess a model’s capability to simulate climate variability on time scales longer than those observable. However, the δ18O measured in speleothem calcite does not directly represent temperature or precipitation but results from multivariate, non-linear processes on top of the dominant meteoric controls on δ18O in precipitation.

Here, we evaluate correlations and networks between different records and power spectral densities across a speleothem database for the past millennium (850-2000CE), testing for representativity of individual records for the time period. Similarity measures are applied to proxy records and to the local climate variables obtained from three isotope-enabled HadCM3 simulations to evaluate simulation biases across different parameters and to distinguish main climate drivers for individual records or regions. The proxy records show strong damping of variability on shorter time scales compared to simulations down-sampled to record-resolution, acting like simple filter processes with realistic time scales for karst transit times.

Based on the evidence from proxies and models for the past 1000 years, we test for realistic parameter constraints and sufficient complexity of a speleothem proxy system model to represent low-latitude changes in climate variability on interannual to centennial timescales.
Molecular evidence for pervasive riverine export of soil organic matter from the Central Himalaya
Authors: Märki Lena , Lupker Maarten , Gajurel Ananta , Gies Hannah , Haghipour Negar , Gallen Sean , France-Lanord Christian , Lavé Jérôme , Eglinton Timothy
Published: March 2020

Soil erosion in high mountain ranges plays an important role in redistributing soil organic carbon across landscapes and may influence the global climate on different timescales [1, 2]. Here, we investigate the dynamics of soil organic matter export in the steep mountain belt of the Himalaya by tracing the provenance of soil-derived lipids in riverine sediments from nested catchments with areas ranging from 370 to 57700 km2.

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a suite of lipids that occur ubiquitously in soils [3, 4]. Their isomer distribution depends on environmental parameters such as the mean annual temperature of the local environment [3]. In this study, we explore the use of brGDGT distributions as a proxy for the altitudinal provenance of soil organic matter in riverine sediments of the Central Himalaya of Nepal. BrGDGT distributions in soils collected along an altitudinal profile, spanning elevations from 200 to 4450 m asl, yield a robust calibration of soil signatures as a function of elevation. This calibration is then used to trace the provenance of soil organic matter exported from their catchments and entrained in suspended sediments of rivers draining the Central Himalaya.

We show that brGDGT compositions of fluvial sediments accurately reflect the mean elevation of the soil-cover in their respective watersheds. The type of land-cover does not seem to have a significant influence on the export of organic matter at a catchment scale. We, therefore, conclude that soil organic matter mobilization in the Himalaya occurs pervasively, and is currently insensitive to anthropogenic perturbations.

 

 

 

[1] Stockmann et al., 2013 – Agriculture, Ecosystems and Environment, 164

[2] France-Lanord & Derry, 1997 – Nature, 390

[3] Weijers et al., 2007 – Geochimica et Cosmochimica Acta, 71

[4] Schouten et al., 2013 – Organic Geochemistry, 54
Drowned Dunes: Integrating 3D GPR and core data to reconstruct a late Holocene buried dune environment.
Authors: Rees-Hughes Luis , Barlow Natasha , Booth Adam , West Jared , Tuckwell George , Grossey Tim
Published: March 2020

During the last two decades, ground-penetrating radar (GPR) methods, have grown in popularity for acquiring high-resolution images of the stratigraphy, internal structure and wider context of geomorphology, as well as the reconstruction and evolution of buried landscapes. GPR offers centimetre-scale resolution of the subsurface, allowing 3D visualization of abrupt changes in palaeo-environments. Although often complemented by core data, GPR interpretations can also be extended beyond regions of ground-truth control. However, for all these advantages, GPR data interpretation can be non-intuitive and ambiguous, with the technique seldom giving images that immediately resemble the expected subsurface geometry. Interpretation can be made yet more onerous when handling the large 3D data volumes that are commonly available with modern GPR technology.

In this paper, we outline the development of a semi-automated GPR feature-extraction tool, based on the image processing techniques ‘Edge Detection’ and ‘Thresholding’. Developed initially for medical image analysis, we investigate them as a means of assisting the analysis of GPR data for subsurface geomorphic features. Given that GPR reflectivity can be related to changes in lithology and/or pore fluids, the structure and extent of subsurface depositional environments can be efficiently estimated using these algorithms. When benchmarked against representative core control, the 3D architecture of the palaeo-landscape can be reconstructed from the GPR dataset.

We present a 500 MHz GPR dataset collected over a buried Holocene coastal dune system in Llanbedr, Gwynedd, North Wales, which has since been reclaimed for use as an airfield. Core data, with maximum depth 2 m, suggest rapid vertical changes from sand to silty-organic units, and GPR profiles suggest that similar lateral complexity is likely across the dataset. By applying thresholding methods to top-down depth slices, the environment is effectively characterised. Furthermore, automatic extraction of the local reflection power with depth yields a strong correlation with the vertical variation of organic content. Similar analyses away from core control could, therefore, deliver a powerful proxy for parameters derived from invasive core logging.
The SECOSTA Project. Citizen science to monitor beach topography with low cost instruments
Authors: Jordà Gabriel , Agulles Miguel , Tomàs-Ferrer Joaquím , Puigdefabregas Joan
Published: March 2020

Beach monitoring plays a fundamental role both for the knowledge of coastal morphodynamics and to assess the risk of coastal flooding. This an very relevant topic for areas in which economies are based on coastal activities like maritime transport or coastal tourim. Unfortunately, up to now the instrumentation and the means required to carry out such monitoring involve very high costs. In consequence, only a limited number of beaches can be studied in detail.

One of the main objectives of the European project SOCLIMPACT is to quantitatively assess the loss of beach surface in the European islands due to projected climate change under different emission scenarios. The main handicap of that activity is to gather accurate information of beach characteristics (topography, bathymetry, granulometry). In order to sort out that problem, the SECOSTA citizen science project has been launched with the support of the Balearic Islands regional government.

In the SECOSTA project, low cost instrumentation based on ARDUINO technology has been developed to measure both the topography and the bathymetry of the beaches. Then, an educational programme has been launched in secondary schools to teach the students to build those instruments and to perform several observational campaigns to characterize sandy beaches along the Balearic Islands. In summary, more than 20 different secondary schools have participated involving more than 2000 students in the construction of devices, acquisition and processing of data. The results have then used as the observational basis for a scientific study about projections of beach retreat in the European islands. Also, both the educational programme and the scientific results have received a broad coverage in the media. With this project, different sectors of citizenship (high school students, teachers, technicians, local government, press etc.,) are directly involved addressing one of the major challenges our society is facing (i.e. sea level rise impacts).  The same approach could  be translated to other fields developing suitable instrumentation.
Submarine landslide recurrence and links to seismicity on the Gorringe Bank Seamount, Offshore Portugal
Authors: Gamboa Davide , Omira Rachid , Terrinha Pedro , Piedade Aldina
Published: March 2020

Submarine landslides are common features occurring on the flanks of seamounts. Often triggered by earthquakes or volcanic activity, such landslides are potential generators of tsunamis that constitute a dire geohazard for coastal communities. Understanding the recurrence history and geomorphology of seamount-flanking landslides and their link to seismic triggers is crucial for tsunami hazard assessment. This work aims at revealing the recurrence history of the landslides on the Gorringe Bank and their role on regional geohazards. Morphologically, the Gorringe Bank is the largest submarine seamount in Europe, with a length of circa 180 km and a height of 5000 m. It is linked to NW-directed thrusting which led to the exhumation of upper mantle lithologies in this major bathymetric structure. Numerous landslide scars are identified on both its northern and southern flanks, yet there is limited evidence of their presence and morphology on modern bathymetric data. A wealth of 2D seismic reflection profiles from offshore Southwest Portugal is here used to analyse the occurrence, timing and morphology of landslides complexes on the northwestern flank of the Gorringe Bank. A widespread frontal landslide complex of approximate Upper Miocene age is present along the whole flank, likely associated with the main phase of uplift. However, the recurrence of expressive submarine landslides in the Plio-Quarternary sequence is generally focused towards the northern segment of the Gorringe Bank. The geographical correlation between the areas of higher landslide number and clusters of seismicity epicentres suggest a close link between the two. This has direct implications for the assessment of landslide-prone locations on the seamount and to regional tsunami hazard models applicable to the Iberian and Northern African margins.

This work is supported by the FCT funded project MAGICLAND - MArine Geo-hazards InduCed by underwater LANDslides in the SW Iberian Margin (Ref: PTDC/CTA-GEO/30381/2017),
Watershed dissolved organic carbon transport: a modeling approach combining water travel times and reactivity continuum
Authors: Grandi Giulia , Bertuzzo Enrico
Published: March 2020

Although their contribution was neglected in the past, inland waters play a significant role in the carbon cycle and affect CO2 global balance. Streams and rivers are now considered not only as pipelines but as active reactors able to collect and transform carbon from terrestrial ecosystems trough drainage, erosion, deposition and respiration. Quantifying the transfer of carbon from the terrestrial to the riverine ecosystems is thus of crucial importance to fully appreciate carbon cycle at the watershed, regional and global scales. Such transfer is largely controlled by the processes occurring in the critical zone where the carbon and water cycles are tightly coupled. Previous studies investigated how hydrological drivers can affect Dissolved Organic Carbon (DOC) concentration in streams highlighting an hysteretic and unsteady behavior for the DOC-discharge relationship. In this study, we focus on the drainage flux from hillslopes to stream and river networks during rainfall events combining a transport model for water and a model of carbon degradation in soil. Using high-frequency records of chloride and DOC in Plynlimon catchments (UK), we employ the recently developed StorAge Selection (SAS) theory to evaluate water travel time and its partition as evapotranspiration, discharge and storage. We combine this approach with the reactivity continuum  theory to model  carbon degradation along the flow paths using a gamma-distribution as probability density function of the quality. The developed model can thus predict not only the flux of DOC released from hillslopes but also its quality (i.e. lability). We also show how the variability of the DOC-discharge relationship can partially be explained by hydrological fluctuations.
CRAMPON: A Particle Filter to assimilate sparse snowpack observations into a semi-distributed geometry
Authors: Cluzet Bertrand , Lafaysse Matthieu , Dumont Marie , Cosme Emmanuel , Albergel Clément
Published: March 2020

In mountainous areas, detailed snowpack models are essential to capture the high spatio-temporal variability of the snowpack. This task is highly challenging, and models suffer from large simulation errors. In these regions, in-situ observations are scarce, while remote sensing observations are generally patchy owing to complex physiographic features (steep slopes, forests, shadows,...) and weather conditions (clouds). This point is stressing the need for a spatially coherent data assimilation system able to propagate the informations into unobserved locations.

In this study, we present CRAMPON (CRocus with AssiMilation of snowPack ObservatioNs), an ensemble data assimilation system ingesting snowpack observations in a spatialized context. CRAMPON quantifies snowpack modelling uncertainties with an ensemble and reduces them using a Particle Filter. Stochastic perturbations of meteorological forcings and the multi-physical version of Crocus snowpack model (ESCROC) are used to build the ensemble. Two variants of the Sequential Importance Resampling Particle Filter (PF) were implemented to tackle the common PF degeneracy issue that arises when assimilating a large number of observations. In a first approach (so-called global approach), the observations information is spread across topographic conditions by looking for a global analysis. Degeneracy is mitigated by inflating the observation error covariance matrix, with the side effect of reducing the impact of the assimilation. In a second approach (klocal), we propagate the information and mitigate degeneracy by a localisation of the PF based on background correlation patterns between topographic conditions.

Here, we investigate the ability of CRAMPON to globally benefit from partial observations in a conceptual semi-distributed domain which accounts for the main features of topographic-induced snowpack variability. We compare simulations without assimilation with experiments assimilating synthetic observations of the Height of Snow and VIS/NIR reflectance. This setup demonstrates the ability of CRAMPON to spread the information of various snow observations into unobserved locations.
How many proxy are necessary to reconstruct the temperature of the last millennium?
Authors: Jaume-Santero Fernando , Barriopedro David , García-Herrera Ricardo , Salcedo-Sanz Sancho , Calvo Natalia
Published: March 2020

Decades of scientific fieldwork have provided extensive sets of paleoclimate records to reconstruct the climate of the past at local, regional, and global scales. Within this context, the paleoclimate community is continuously undertaking new measuring campaigns to obtain long and reliable proxies. However, as most paleoclimate archives are restricted to land regions of the Northern Hemisphere, increasing the number of proxy records to improve the skill of climate field reconstructions might not always be the best strategy.

 

By generating pseudo-proxies from several model ensembles at the locations matching the records of the PAGES-2k network, we show how biologically-inspired artificial intelligence can be coupled with reconstruction methods to find the set of representative locations that minimizes the bias in global temperature field reconstructions induced by the non-homogeneous distribution of proxy records.

 

Our results indicate that small sets of perfect pseudo-proxies situated over key locations of the PAGES-2k network can outperform the reconstruction skill obtained with all available records. They highlight the importance of high latitudes and major teleconnection areas to reconstruct temperature fields at annual timescales. However, long-term temperature variations are better reconstructed by records situated at lower latitudes. According to our experiments, a careful selection of proxy locations should be performed depending on the targeted time scale of the reconstructed field.
Challenges and opportunities extending the INTIMATE tephra event stratigraphy into the Levant and Arabia.
Authors: Blockley Simon , White Dustin , Timms Rhys , Lincoln Paul , Armitage Simon , Stringer Chris
Published: March 2020

The nature and expression of climate change in the Eastern Mediterranean, the Levant and further into Arabia is of considerable interest across a range of communities. This is in part due to the need to understand the potential for future climate forcing on environments given the complex range of climatic forcing factors that play out in the region. These include the role of prevailing winds across the Mediterranean, Northerly winds pushing down into the region during cold glacial conditions, and the influence of the Afro-Arabian Monsoon. The last glacial to interglacial period is a critical window to examine such processes, as a range of climatic signals are recorded, many of which have been proposed as correlatives of events seen in the North Atlantic. Dating issues are as ever an issue when trying to precisely compare different climate archives. To address such, the INTIMATE event stratigraphy has been developed for the North Atlantic region, with recent extensions into parts of the Mediterranean. This couples the stratigraphic framework of the Greenland Ice core records as a regional stratotype, with  a number of tephra horizons in the North Atlantic and Europe, aiding the process of correlation. The last INTIMATE event stratigraphy coupled the extended GICC05 timescale for Greenland back to 128 b2k (Blockley et al., 2014). This paper reports on attempts to test the potential for tephrochronology to be extended into the Levant and potentially Arabia, through the identification of tephra layers in sediment focussing archives, such as archaeological cave sequences. We have examined tephra presence in archaeological sites, principally in Israel, that record sediment deposition from ~30ka BP through to >100ka BP. Analyses of these records show that tephra is present in almost all of the studied sites (e.g., Kebara, Tabun, Amud, Shovakh). Moreover, tephra in these sequences can be chemically correlated to known volcanic systems, demonstrating the potential going forward to analyse long lake and marine records around the region for cryptotephra. At the same time clear challenges are emerging. Firstly, there is a range of chemistry in many of the layers and careful analyses is needed to pick apart the geochemical signal and to identify reworking, as opposed to chemically heterogeneous ash layers from a single volcano. This process is complicated by the relatively limited range of published geochemical data from some volcanic centres. This presentation will outline the current state of knowledge of key volcanic centres, particularly in the Aegean and Turkey, alongside the new Levantine data, to consider the steps needed to establish a secure extension of the INTIMATE approach into this region.

Blockley, S., et al., 2014. Quaternary Science Reviews. 106, 88-100. doi:10.1016/j.quascirev.2014.11.002.
Quantitative land-cover change in West Africa over the Holocene: case study in Cameroon
Authors: Githumbi Esther , Gaillard Marie-Jose , Lezine Anne-Marie , Achoundong Gaston , Hély Christelle , Lebamba Judicael , Marquer Laurent , Mazier Florence , Sugita Shinya
Published: March 2020

Currently interaction between climate and land-cover change in the past across the globe, and whether drivers are anthropogenic or natural are among the biggest debates. The impacts of climate and land-cover change are having significant consequences on biodiversity and ecosystems. Wide ranging palaeoenvironmental methods have contributed to this debate by providing long-term records of both climate and land-cover change. This provide the context for evaluating the effect of land-cover change on climate.  Inferred past land-cover and climate change from palaeoecological proxies therefore need to be quantified to provide reliable estimates of change; there are several methods of quantifying land-cover change in the past of which the Landscape Reconstruction Algorithm (LRA)  can estimate past land-cover change quantitatively at both regional and local spatial scales using fossil pollen records. The LRA includes two models (REVEALS and LOVE) and has already been tested and validated in Europe, North America, and China.

In this study, we apply the LRA on Holocene pollen records in Cameroon to estimate past land-cover change. This is the first pollen-based, quantitative land-cover reconstruction using LRA in Africa.  It will provide a comparison with land-cover change described from raw pollen data and useful information for climate modelling. The first phase involved the estimation of relative pollen productivity (RPP) for 13 taxa using the pollen-vegetation relationship described by the ERV model. The second phase involves the application of LRA using the RPPs from the 13 taxa.

 

 Acknowledgements: We thank the French ANR (National Research Agency; projects C3A ANR-09-PEXT-001 and VULPES ANR-15-MASC-0003) and the Belgian project BR/132/A1/AFRIFORD for financial support, IRD (France) and the Ministry of Research and National Herbarium of Cameroon for research facilities and authorizations, and A. Vincens, J.-P. Cazet, G. Buchet, L. Février, and K. Lemonnier (CNRS) for laboratory and field assistance. The study is a contribution to PAGES LandCover6k (www.pastglobalchanges.org/ini/wg/landcover6k/intro).
How good are my stable isotope data? Implications on using an in-house Quality Control system for stable isotope measurements
Authors: Soto David X. , Assonov Sergey , Grant Helen , Pereira M. Glória , Fajgelj Ales
Published: March 2020

Stable isotopes are widely used with applications in forensics, ecology, biogeochemistry, atmospheric sciences, and hydrology. Isotope data are frequently compared and combined, which requires data of high quality. This brings to the attention how comparable the data is and the need for an internal Quality System in research and service laboratories to support data quality. Since the amount of isotope data produced in the recent years has increased considerably, a plea for high-quality isotope data is required.  Estimations of data quality including uncertainty calculations may be complicated by various and not well-controlled factors, including sample matrix effects, incomplete reactions and byproducts formed etc. The use of data scatter (e.g. Standard deviation of certified reference materials and in-house working standards) as a measure of uncertainty is obviously insufficient. Instead, one may consider other or combined data quality indexes. The use of a simplified uncertainty estimation together with z-scores calculation enhances the assessment of lab performance and quality and increases the likelihood to accept the target performance chosen by any isotope laboratory. However, uncertainties associated to unknown samples also reduces the probability of obtaining significant differences between sample groups, which the purpose of the analysis could not fit. Here we discuss the criteria to revise limits of QC materials (e.g. lab standards) in an objective manner including the removal of outliers. Warning and action limits depend on the stable isotopic composition of the material (enriched vs. natural abundance), the homogeneity of the material, and the statistical approach utilized. We will report data of 1-2 years of QC tools of a soil standard material obtained at the laboratory in UKCEH-Lancaster and we will discuss how to deal with internal QC system including outlier removal, sample preparation issues, etc. Implementation of these or similar QC protocols are of great relevance for a well-based decision making when using isotope results.
The practice of reclaimed land be converted to arable land in China
Authors: Kong Xiangbing , Wen Liangyou
Published: March 2020

 

Land reclaim can be converted to arable land in China. Land reclamation is the process of reclamation and restoration to arable land on the basis of the original abandoned independent land. It mainly includes: land for coal mines, quarries, brick kilns, warehouses, other enterprises and institutions, and abandoned rural construction land. As of 2015, China's construction activities and natural disasters have damaged about 10 million hm2 of land, with an annual increase of about 270,000 hm2. China's land reclamation rate is about 45%, of which about 50% of the land reclaimed is arable land. China has a large number of land reclamation practices and has very rich experience. First, we carried out land adaptability evaluation in the reclamation area .we selected the currently land for coal mines, quarries, brick kilns, warehouses, and other enterprises and institutions from natural, economic, and social aspects to evaluate its suitability, comprehensively calculated the consolidation potential, and calculated the area that could be reclaimed as arable land. Second, we carried out arable land construction in the reclamation area. Through land consolidation methods such as land leveling, farmland irrigation and drainage construction, shelterbelt network layout, and farmland road construction, rural residential areas that can be reclaimed as arable land, which will be sorted higher productivity arable land with a centralized patch, good irrigation and drainage , and complete farmland roads. Third, according to the soil conditions of the reclamation area, we carry out soil fertilization. We plowed the soil, applyed organic manure and soil biochar, improved soil water retention and porosity, enhanced soil fertility, improved arable land quality, and increased land production potential. Finally, after the land is reclaimed as arable land, we will monitor the soil conditions and ecological environment of the newly reclaimed arable land on a regular basis through the establishment of a regulatory agency. As same time, while we tried to meeting the fertility of the newly reclaimed arable land, we moinitor the ecological environment of the newly reclaimed land, ensuring sustainable use of arable land. Through the land reclamation, the per capita arable land area in the country have be increased by 0.08 mu. the annual grain yield per mu is calculated at 400kg, which increased 40 billion kg of grain each year. what’s more, farmers have increased the area of ​​arable land, increased their family income, and let themselves live better. By land be reclaimed to arable land, Chinese government has effectively protected 1.2 billion hm2 of Red line of arable land and ensured national food security. At same time, farmers' income was increased by increasing of crop area, and intensive land conservation has been achieved, which has solved our country to a certain extent.
Finding the right tree for future urban planning – Meso- to microscale model coupling in urban areas
Authors: Fallmann Joachim , Simon Helge , Sinsel Tim , Barra Marc , Tost Holger
Published: March 2020

It has been long understood that green infrastructure helps to mitigate urban heat island formation and therefore should be a key strategy in future urban planning practices. Due to its high level of heat resilience, the sycamore tree (Platanus) dominates the appearance of urban landscapes in central Europe. Under extreme climate conditions however, these species tend to emit high levels of biogenic volatile organic compounds (BVOCs) which in turn can act as precursors for tropospheric ozone, especially in highly NOx polluted environments such as urban areas.

Assessing the ozone air quality of a large urban area in Germany we use the state-of-the art regional chemical transport model MECO(n), with chemistry coming from the Modular Earth Submodel System (MESSy) and meteorology being calculated by COSMO. Including the latest version of TERRA_URB, the model is configured for the Rhine-Main urban area. In a second step, we implement parts of the regional atmospheric chemistry mechanism in the ENVI-met model framework in order to investigate the impact of isoprene emissions on ozone concentration at street level for the urban area of Mainz, Germany.

Whereas mesoscale model results only show moderate mean ozone pollution over the model area, at micro-scale level on selected hot spots we find a clear relationship between urban layout, proximity to NOx emitters, tree-species-dependent isoprene emission capacity and increase in ozone concentration. The ENVI-met study reveals, that next to tree species, its location is a key factor for its micro-climatic UHI and air pollution mitigation potential. We could show, that isoprene related ozone concentration is highly sensitive to leaf temperature, photosynthetic active radiation as well as to the proximity to NO2 pollution sources. In a street canyon with high traffic load we find significant correlations between diurnal boundary layer dynamics, morning and evening rush hour and ambient ozone levels. For a hot summer day in particular, we simulate ozone concentrations rising up to 500% within a weakly ventilated street canyon with a high amount of strong isoprene emitters being present.

We summarize that combining findings from meso- and microscale model systems can be an important asset for science tools for cities in the framework of climate change adaption and mitigation and air pollution abatement strategies.
Hemispherical underground borehole heat exchanger field as a source of geothermal energy
Authors: Korhonen Kimmo , Hietava Jaakko , Ahonen Lasse
Published: March 2020

Finland is located between the 60th and 70th northern parallels and is characterized by continental subarctic climate. Due to climatic conditions, ground surface temperatures are low in Finland. The long-term average annual ground surface temperature ranges from 0.5 to 7.6 °C. Decommissioned mines offer a way to tap into larger geothermal resources by allowing access to deep underground where the temperature regime is more beneficial for heat extraction than in the shallow ground. The Energy Mine project was initiated to investigate how the Pyhäsalmi deep mine could be utilized to tap into the deeper geothermal resources of the Finnish bedrock.

The depth level of the deepest mine tunnel in the Pyhäsalmi mine is 1,440 m. We took this tunnel as the starting point for our study since it offers access to the largest geothermal resources that are accessible from the mine. We modelled the thermal performance of borehole heat exchanger (BHE) fields constructed by drilling the boreholes from a single site in different azimuth and tilt angles so that the resulting BHE fields took the form of a lower hemisphere. The borehole length was 300 m. The collector was coaxial open-loop with an insulated pipe. Bedrock temperatures within the depth range of the BHE fields ranged from 21 to 25 °C. Finite element models were constructed to simulate the operation of various configurations of hemispherical BHE fields. In all simulations, the temperature of the heat carrier fluid fed to the inlets of the BHEs was kept at 6 °C during the 100 simulated years.

The results indicate that it would require at least 145 BHEs for a hemispherical BHE field to sustain at least 1 MW of heating power from the bedrock for 25 years. Such a field would produce 300 GWh of heating energy during the first 25 years. This amount can be increased by adding boreholes to the field. However, at some point, adding BHEs no longer increases the amount of thermal energy that can be extracted from a hemispherical BHE field. The maximum amount of extractable energy is somewhere around 1.2 TWh which is the estimated heat content of a hemispherical volume of bedrock at the tunnel depth.

The hemispherical design is not the most optimal BHE field design with respect to thermal performance because the distances between BHEs become very small at the drilling site. However, the spatial restrictions imposed by mine tunnels do not allow much leeway in BHE field design. Another possibility is to construct a BHE field along a mine tunnel. But even in this case the BHEs would need to be drilled in a fan-like fashion at several drilling sites along the tunnel length. The hemispherical design is advantageous with respect to drilling and piping compared to a BHE field that is constructed along the length of a mine tunnel.
Evolution of the Earth’s polar wind escape from mid-Archean to present
Authors: Kislyakova Kristina , Johnstone Colin , Scherf Manuel , Lammer Helmut , Holmström Mats , Khodachenko Maxim , Güdel Manuel
Published: March 2020

The evolution of habitable conditions on Earth is tightly connected to the evolution of its atmosphere which, in turn, is strongly influenced by atmospheric escape. We investigate the evolution of the the polar wind outflow from the magnetic cusps which is the dominant escape mechanism on the Earth. We perform Direct Simulation Monte Carlo (DSMC) simulations and estimate the upper limits on escape rates from the Earth's cusps starting from three gigayears ago (Ga) to present assuming the present-day composition of the atmosphere. We perform one additional simulation with a lower mixing ratio of oxygen of 1% to account for the conditions shortly after the Great Oxydation Event (GOE). We account for the evolution of the magnetic field of the Earth by adjusting the polar opening angle and the location of the magnetosphere's substellar point.

Our results present an upper limit on the escape rates, but they indicate that polar wind escape rates for nitrogen and oxygen ions were likely much higher in the past.  We estimate the maximum total loss rates due to polar wind of 2.0x1018 kg and 5.2x1017 kg for oxygen and nitrogen, respectively. According to our results, the main factors that governed the polar wind outflow in the considered time period are the evolution of the XUV radiation of the Sun and the atmosphere's composition. The evolution of the Earth's magnetic field plays a less important role. We conclude that although the atmosphere with the present-day composition can survive the escape due to polar wind outflow, a higher level of CO2 between 3.0 and 2.0 Ga is likely necessary to reduce the escape.
New simple approach to understand the spatial and vertical distribution of biomass burning CO emission based on the MOPITT vertical measurements
Authors: Lin Chuyong , Cohen Jason
Published: March 2020

A simple variance-maximization approach, based on 19 years of weekly Moderate Resolution Imaging spectroradiometer (MOPITT) CO vertical measurements, was employed to quantify the spatial distribution of the global seasonal biomass burning region. Results demonstrate there are a few large-scale and typical biomass burning regions responsible for most of the biomass burning emissions throughout the world, with the largest of these such regions located in Amazonian South America, Western Africa, Indonesia, and Northern Southeast Asia (Eastern India, Northern Myanmar, Laos, Vietnam and Eastern Bangladesh), which are highly associated with the results of Global Fire Emission Database(GFED). The CO is primarily lofted to and spreads downwind at 800mb or 700mb with three exceptions: The Maritime Continent and South America where there is significant spread at 300mb consistent with known deep- and pyro-convection; and Southern Africa where there is significant spread at 600mb. The total mass of CO lofted into the free troposphere ranges from 46% over Central Africa to 92% over Australia.
Product dependency of Fire-driven surface albedo radiative forcing global estimates: a spatial and temporal consistency analysis
Authors: Mota Bernardo , Gobron Nadine , Lanconelli Christian , Capucci Fabrizio
Published: March 2020

This paper addresses the product consistency in a cross-ECV model space driven ECV’s to estimate the radiative forcing (RF) due to the direct effect of fire- driven surface albedo change. Monthly radiative forcing’s are modeled using three Earth Observation land surface albedo (MCD43C3, GlobAlbedo and Copernicus Global Land Services) and five burnt area (FireCCIv4, FireCCIv5, MCD45C5, MCD64C6 and Copernicus Global Land Services) products, and the ERA5 downward Solar radiation at the Surface. The ensemble consistency is analyzed spatially and seasonally by vegetation cover type using the Land Cover CCI product, and using four spatial resolutions (0.05°, 0.10°, 025° and 0.5°). Results show that depending on the combined products and spatial resolution, estimates can differ significantly. In general, higher estimates result at coarser resolutions and variation between product combinations can differ between 26% to 46%, depending on the type of vegetation. In addition, significant temporal trends of opposing signs can be detected. This study presents an example of cross-ECV modelling. Due to the increasing number, and coverage, of Earth Observation satellite programs, these results highlight the need to assess the fitness for purpose of the derived products.
Data-driven modelling of erupting solar active regions
Authors: Price Daniel , Pomoell Jens , Lumme Erkka , Kilpua Emilia
Published: March 2020

Fully understanding solar eruptions and their eventual consequences for the Earth requires a rigorous modelling approach due to the difficulty of directly measuring magnetic fields in the solar corona. Consequently, this study employs a time-dependent data-driven magnetofrictional model (TMFM) to simulate the coronal evolution of coronal mass ejections from multiple active regions. We processed HMI vector magnetograms with the Electric Field Inversion Toolkit to generate a time series of photospheric electric field maps which were used as the lower boundary to drive our TMFM simulations. Analysis was aided by computing maps of the squashing factor and twist, as well as by calculating coronal metrics such as the volume energy and helicity, and by comparison to AIA observations. Studying multiple events simultaneously permits comparative analysis and the evaluation of the model performance.