bluuebunny/crossref_metadata_2025 huggingface dataset:
UAV-based mapping of radioactive contamination of uranium mining legacies in Central Asia
Authors: Altfelder Sven , Arndt Robert , Ibs-von Seht Malte , Kunze Christian , Preugschat Benedikt , Schröder Marius , Schulz Hartmut , Wiens Benjamin
Published: March 2020

In the Central Asian countries of Kyrgyzstan, Tajikistan, Uzbekistan and Kazakhstan, uranium production activities during the Soviet era have led to a large number of mining legacies. The mining residues can show significant levels of radioactive contamination. Due to the mountainous landscape and the geotechnical conditions at these sites, there is a risk of uncontrolled release of radioactive contaminants into the environment and into cross-border rivers in the region. The situation is exacerbated further by the fact that the countries are prone to natural hazards such as earthquakes, floods, mudflows and landslides. There is an urgent need to map locations, extent and inventory of the contaminated areas in order to be able to support remediation measures and monitor the long-term stability of the remediated legacies.
The research project DUB-GEM funded by the German Federal Ministry of Education and Research (grant no. 01LZ106A-C) deals with the development of a UAV-based gamma spectrometry for the exploration and monitoring of uranium mining legacies. The aim of the three-year project is to develop and apply a method that allows regulatory authorities and operators to map contaminated sites rapidly and economically using gamma spectrometers mounted on a UAV (unmanned aerial vehicle). The main tasks of the project are to select and configure suitable detectors, to develop flight, measurement, and data processing strategies and to design an airframe that is ideally suited to carry out the surveys. In this contribution we present the current status of the project, including the design of the UAV prototype, results of the first test and calibration measurements with the selected gamma spectrometers and an outlook on upcoming project activities.
Limited Retreat of the Wilkes Basin Ice Sheet during the Last Interglacial.
Authors: Sutter Johannes , Eisen Olaf , Werner Martin , Grosfeld Klaus , Kleiner Thomas , Fischer Hubertus
Published: March 2020

The response of the marine sectors of the East Antarctic Ice Sheet to future global warming represents a major source of uncertainty in sea level projections. If greenhouse gas emissions continue unbridled, ice loss in these areas may contribute up to several meters to long-term global sea level rise. In East Antarctica, thinning of the ice cover of the George V and Sabrina Coast is currently taking place, and its destabilization in past warm climate periods has been implied. The extent of such past interglacial retreat episodes cannot yet be quantitatively derived from paleo proxy records alone. Ice sheet modelling constrained by paleo observations is therefore critical to assess the stability of the East Antarctic Ice Sheet during warmer climates. We propose that a runaway retreat during the Last Interglacial of the George V Coast grounding line into the Wilkes Subglacial Basin would either leave a clear imprint on the water isotope composition in the neighbouring Talos Dome ice-core record or prohibit the preservation of an ice core record from the Last Interglacial alltogether. We test this hypothesis using a dynamic ice sheet model and infer that the marine Wilkes Basin ice sheet remained stable throughout the Last Interglacial (130,000-120,000 years ago). Our analysis provides the first constraint on Last Interglacial East Antarctic grounding line stability by benchmarking ice sheet model simulations with ice core records. Our findings also imply that ambitious mitigation efforts keeping global temperature rise in check could safeguard this region from irreversible ice loss in the long term.
GRACEFUL: Probing the deep Earth interior by synergistic use of observations of the magnetic and gravity fields, and of the rotation of the Earth
Authors: Mandea Mioara , Dehant Veronique , Cazenave Anny
Published: March 2020

To understand the processes involved in the deep interior of the Earth and explaining its evolution, in particular the dynamics of the Earth’s fluid iron-rich outer core, only indirect satellite and ground observations are available. They each provide invaluable information about the core flow but are incomplete on their own:

-        The time dependent magnetic field, originating mainly within the core, can be used to infer the motions of the fluid at the top of the core on decadal and subdecadal time scales.

-        The time dependent gravity field variations that reflect changes in the mass distribution within the Earth and at its surface occur on a broad range of time scales. Decadal and interannual variations include the signature of the flow inside the core, though they are largely dominated by surface contributions related to the global water cycle and climate-driven land ice loss.

-        Earth rotation changes (or variations in the length of the day) also occur on these time scales, and are largely related to the core fluid motions through exchange of angular momentum between the core and the mantle at the core-mantle boundary.

Here, we present the main activities proposed in the frame of the GRACEFUL ERC project, which aims to combine information about the core deduced from the gravity field, from the magnetic field and from the Earth rotation in synergy, in order to examine in unprecedented depth the dynamical processes occurring inside the core and at the core-mantle boundary.
How do cirques form in ocean island volcanoes: the case of Piton des Neiges (Réunion Island, Indian Ocean)
Authors: Paquez Camille , Famin Vincent , Villeneuve Nicolas , Michon Laurent , Bénard Bhavani
Published: March 2020

“Cirques” are funnel-shaped, seaward-narrowing valleys commonly observed on many volcanic islands worldwide, such as Tahiti (French Polynesia), La Palma or Gran Canaria (Canary), Anjouan (Comores), and Maui or Molokai (Hawai’i). Because they contradict the basics of regressive erosion by rivers, these geomorphic structures have been interpreted in many ways, including the erosion of volcano-tectonic depressions (crater, caldera, rift zone), the formation of leaf grabens caused by volcano spreading, or the subsidence of dense plutonic bodies within edifices. Piton des Neiges volcano (Réunion Island) is dissected by three cirques (Salazie, Mafate and Cilaos) and thus provides an excellent case to study the processes that lead to the formation of these funnel-shaped valleys. To do so, we performed a detailed field and photogrammetric mapping of the volcanic and volcaniclastic products outcropping in the cirques using an updated chrono-stratigraphy.

Our mapping reveals that the three cirques of Piton des Neiges are not delimited by faults, which excludes vertical movements as the primary cause of their formation. Rather, the cirques are built on former horseshoe-shaped depressions filled with volcaniclastic breccias (mostly related to debris avalanches and debris flows), and later covered by lava flow units. Importantly, the breccia are several hundred meters thick in the innermost parts of the cirques, but thin out until complete disappearance toward the outer flanks of the volcano.

In consequence, we interpret the basal volcaniclastic breccias as playing a major role in the formation of the cirques, by offering a weaker resistance than the lava flow units. This contrasted resistance leads to greater erosion rates on the inside of the volcano than on the outer flanks and, hence explaining the reverted funnel shape of the cirques. In our model, cirques are therefore erosional structures mostly guided by past dismantling episodes rather than by tectonic or volcano-tectonic structures.
Supporting Multi-cloud Model Execution with VLab
Authors: Santoro Mattia , Mazzetti Paolo , Spadaro Nicholas , Nativi Stefano
Published: March 2020

The VLab (Virtual Laboratory), developed in the context of the European projects ECOPOTENTIAL and ERA-PLANET, is a cloud-based platform to support the activity of environmental scientists in sharing their models. The main challenges addressed by VLab are: (i) minimization of interoperability requirements in the process of model porting (i.e. to simplify as much as possible the process of publishing and sharing a model for model developers) and (ii) support multiple programming languages and environments (it must be possible porting models developed in different programming languages and which use an arbitrary set of libraries).

In this presentation we describe how VLab supports a multi-cloud deployment approach and the benefits.

In this presentation we describe VLab architecture and, in particular, how this enables supporting a multi-cloud deployment approach.

Deploying VLab on different cloud environments allows model execution where it is most convenient, e.g. depending on the availability of required data (move code to data).

This was implemented in the web application for Protected Areas, developed by the Joint Research Centre of the European Commission (EC JRC) in the context of the EuroGEOSS Sprint to Ministerial activity and demonstrated at the last GEO-XVI Plenary meeting in Canberra. The web application demonstrates the use of Copernicus Sentinel data to calculate Land Cover and Land Cover change in a set of Protected Areas belonging to different ecosystems. Based on user’s selection of satellite products to use, the different available cloud platforms where to run the model are presented along with their data availability for the selected products. After the platform selection, the web application utilizes the VLab APIs to launch the EODESM (Earth Observation Data for Ecosystem Monitoring) model (Lucas and Mitchell, 2017), monitoring the execution status and retrieve the output.

Currently, VLab was experimented with the following cloud platforms: Amazon Web Services, three of the 4+1 the Coperncius DIAS platforms (namely: ONDA, Creodias and Sobloo) and the European Open Science Cloud (EOSC).

Another possible scenario empowered by this multi-platform deployment feature is the possibility to let the user choose the computational platform and utilize her/his credentials to request the needed computational resources. Finally, it is also possible to exploit this feature for benchmarking different cloud platforms with respect to their performances.

 

References

Lucas, R. and A. Mitchell (2017). "Integrated Land Cover and Change Classifications"The Roles of Remote Sensing in Nature Conservation, pp. 295–308.

 
Dissolution precipitation creep as a process for the strain localisation in gabbro
Authors: Lee Amicia , Stunitz Holger , Battisti Matheus Ariel , Konopasek Jiri
Published: March 2020

Strain localisation and fabric development in the lower crust is controlled by the active deformation mechanisms. Understanding the driving forces of such deformation aids in quantifying the stresses and rates of the deformation processes. Here we show that diffusion creep plays a major role in deformation of gabbro lenses at upper amphibolite facies conditions. The Kågen gabbro in the North Norwegian Caledonides intruded the Vaddas Nappe at 439 Ma at pressures of 7-9 kbar, temperatures of 650-900°C (depths of ∼26-34 km). The Kågen gabbro on south Arnøya is made up of undeformed gabbro lenses with sheared margins wrapping around them. This contribution analyses the evolution of the microstructures and fabric of the low strain gabbro to high strain margins. Microstructural and textural data indicate that preferential crystal growth of amphibole grains in the extension direction has produced the deformation microstructure and the CPO. Dissolution precipitation creep is inferred to be the dominant deformation mechanism, where dissolution of the gabbro took place in reacting phases of clinopyroxene and plagioclase, and precipitation took place in the form of new minerals: amphibole, garnet and zoisite. Synchronous deformation and mineral reactions of clinopyroxene suggests mafic rocks can become mechanically weak during the general transformation weakening process, i.e. the interaction of mineral reaction and deformation by diffusion creep. Deformation and metamorphic reaction were both important transformation processes during diffusion creep deformation of the margins of the gabbro lenses. The weakening is directly connected to a transformation process that facilitates diffusion creep deformation of strong minerals (pyroxene, garnet, zoisite) at far lower stresses than dislocation creep. Initially strong lithologies can become weak, provided that reactions can proceed during deformation, the transformation process itself is an important weakening mechanism in mafic (and other) rocks, facilitating deformation at low differential stresses.
An Analysis of the Characteristics of Adjacent Climatic Factors Affecting Extreme Snowfall on the Korean Peninsula
Authors: Bae Young Hye , Jung Jaewon , Necesito Imee V. , Kim Soojun , Kim Hung Soo
Published: March 2020

Due to global warming, Arctic temperatures are rising, resulting in the fall of polar vortex, a cold Arctic air, causing heavy snow and a record-breaking cold wave in the middle latitude northern hemisphere. A record-breaking cold wave and extreme snowfall have paralyzed infrastructure and caused enormous human and property damage. In this study, we analyzed the deployment characteristics of winter climate that affect the extreme snowfall on the Korean Peninsula. The European Centre for Medium-Range Weather Forecasting (ECMWF) data provided by the Copernicus Climate Change Service (C3S) was used to analyze the characteristics of climate factors around the Korean Peninsula. The period of all data was from November to March, the winter season of South Korea. Teleconnections were analyzed using climatic factors such as snowfall, humidity, air pressure, wind and sea surface temperature to analyze the characteristics of climate factors affecting the heavy snowfall on the Korean Peninsula. The results of the future main study are expected to be used as basic data to predict the occurrence and impact of heavy snow in areas surrounding the Korean Peninsula in the future and to assess its vulnerability to damage from the snowfall.
Impact of sea level variations on hydrographic survey around Taiwan
Authors: Lan Wen-Hau , Kuo Chung-Yen , Lin Sheng-Fong , Lu Chien-Hsing
Published: March 2020

Taiwan is an island entirely surrounded by oceans, so living and economics are significantly influenced by the oceans. The electronic navigational chart system is extremely important for improving the safety of marine navigation and ocean depth is the essential data for electronic charts. Sea surface variations affected by ocean tide and sea level change are the main error sources in hydrographic surveys since the traditional tidal correction only using tide gauge stations, ignoring geographically non-uniform ocean tides and sea level anomalies around Taiwan. In this research, we evaluate two factors impacting the accuracy of hydrographic surveys, including ocean tides and seasonal sea level variations, using tide gauge records, satellite altimeter data and ocean tide models around Taiwan, and also analyze the accuracy of the ocean tide models around Taiwan. In addition, sea level anomalies are strongly influenced by climate changes in recent years. An understanding of seasonal sea level cycle and its spatial and temporal changes are importance because its temporal changes can result in the variation of the frequency and magnitude of coastal hazards. Therefore, we will apply the Ensemble Empirical Mode Decomposition to sea level data to assess the stability of the long-term seasonal sea level fluctuations with time.
Added Value of reproduced precipitation by high resolved regional climate model simulation over CORDEX-East Asia
Authors: Kim Taehyung , Cha Dong-Hyun , Kim Gayoung , Shin Seok-Woo , Park Changyong , Lee Minkyu , Byun Young-Hwa , Kang Hyun-Suk
Published: March 2020

In the framework of the CORDEX-East Asia, evaluation simulations using high-resolution regional climate models (SNURCM and HadGEM3-RA) with ~25km (Phase2) grid scale have been conducted. In this study, we investigate whether the higher-resolution regional climate models (RCMs) can generate added values for summer mean precipitation, large-scale circulation, and extreme precipitation compared to those with lower-resolution (~50km, Phase 1). In addition, the added value index is used to quantitatively analyze the abilities of fine- and coarse-resolution RCMs. Hence, sets of phase 1 and phase 2 simulations of two RCMs are compared to observations in the East Asia region. In SNURCM simulations, positive (negative) added value of summer mean precipitation is reproduced over most ocean (land) region of East Asia in fine-resolution simulation. Extreme precipitation over Korea and Japan is well reproduced in Phase 2 simulations because the simulations of typhoons and East Asia summer monsoon are improved. In HadGEM3-RA simulations, the results of summer mean precipitation over most East Asian regions above 25°N are improved in Phase 2, while worse results are reproduced below 25°N. But, extreme precipitation in fine-resolution simulation is adequately reproduced in most regions of East Asia except China and the Yellow sea. As a result, the results of the simulations are different depending on the characteristics of the individual models, but more positive added values for the intensity and spatial distribution of precipitation over East Asia are generated as the horizontal resolution of RCMs increases.

This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI(KMI2018-01211)

 
New approaches to decadal predictions on the regional scale
Authors: McCarthy Gerard , Düsterhus André , O'Beirne Catherine , Ogungbenro Stephen , Diabate Samuel T. , Caesar Levke , Upton Maeve C. , Cahill Niamh , Parnell Andrew C.
Published: March 2020

The North Atlantic has a major influence on the climate of Europe. In the past, decadal prediction systems have shown consistent prediction skill in the North Atlantic for initialised models, indicating the potential to exploit this skill for better predictions on the continent. One prime area of potential for this approach is Ireland, due to its proximity to the Atlantic.

Until now, the prediction skill for the island of Ireland is limited, leading to the conclusion that dynamical models alone are not able to transfer the prediction skill from the North Atlantic to the surrounding land masses. Therefore, the project Aigéin, Aeráid, agus athrú Atlantaigh (A4) aims to establish new physical and statistical approaches to enhance the skill. This includes a better understanding on the oceanographic processes leading to the prediction skill in the North Atlantic as well as usage of statistical-dynamical predictions.

This contribution will give an overview of the approaches and a first look on the factors we anticipate to use in our analysis. Special attention will be given to the statistical approaches for the statistical dynamical prediction as well new verification procedures to evaluate them.
Rain drop size distribution (RSD) associated with precipitation types in the middle zone of the Santa River catchment, Peru
Authors: Robles Sánchez Danny , Figueroa Tauquino Rafael , Fernández Rosales Ciro , Villanueva Ramírez Ricardo , Huggel Christian , Seidel Jochen , Muñoz Randy , Motschmann Alina
Published: March 2020

At present, climate change is modifying rainfall regimes at a global level with effects on local activities as well as changes in the variability of perceptible rainfall at a very short time scale. This phenomenon places in a scenario of high vulnerability to all activities that depend on rainfall for its development. In this sense, the detailed knowledge of the patterns and microphysical characteristics of the precipitations that occurred in the middle zone of the Santa River catchment (Western Andes of Peru) is of high importance mainly for dryland agricultural activity.

On the one hand, there is the presence of intense precipitation that causes erosion and, on the other hand, precipitation of less intensity beneficial for the improvement of the soil structure. In this regard one of the main parameters that define the characteristics of precipitation and are directly related to the origin of its formation (convective and stratiform) and intensity is the distribution of the size of raindrops (RSD). Through RSD the type of precipitation occurred in the catchment can be defined and classified.

In such context, the main objective of the study is to characterize the distribution of the size of raindrops and associate them with a type of precipitation. For this we use the Micro Radar of Precipitation (MRR-2) installed in the city of Huaraz (between the Cordillera Blanca and Cordillera Negra), with data from March 2017 to December 2019 (34 months). A frequency analysis with the distribution data of RSD is carried out as well as an analysis of main components to relate it to a type of rain. The results reveal the different types of rainfall that occurred in the area during the analysis period, and also identify the periods and frequencies of these rains due to the current weather patterns.
Gravity modeling of the volcanic island of Surtsey, Iceland
Authors: Sayyadi Sara , T.Gudmundsson Magnús , Högnadóttir Thórdís , White James , D. Jackson Marie
Published: March 2020

The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones.   A detailed gravity survey was carried out on Surtsey in July 2014 with a gravity station spacing of ~100 m.  We analyse these data in order to refine a 2.5D-structural and density model of the internal structure for this type locality of Surtseyan volcanism.  We carry out a complete Bouguer correction of these data using total terrain corrections based on detailed DEMs of the island and the submarine bathymetry.  The principal components of the island are the two tuff cones composed principally of lapilli tuff; this was originally phreatomagmatic tephra formed in the explosive phases of the eruption. Lapilli tuff can be subdivided into (1) submarine lapilli tuff and (2) lapilli tuff above sea level. Other units are (3) subaerial lava, and (4) subaqueous lava deltas. Minor components that are volumetrically insignificant are small intrusions, and unconsolidated and unaltered tephra, still found in thin layers flanking the tuff cones.  An additional formation, relevant for any analysis of the subsurface structure of Surtsey, is (5) the sedimentary rocks making up the seafloor, being at least 100 m thick but probably much thicker.  Using measurements of the density of all the above components, and subdividing the island into different units based on its pattern of growth, we specifically attempt to constrain the width and depth of diatreme structures proposed by Moore (1985) and confirmed in the ICDP SUSTAIN drilling of Surtsey in 2017 (Jackson et al., 2019).  Our forward modeling is aided by a detailed subdivision of the island into units (1) to (4) based on repeated mapping of the island during 1964-1967.

 

Moore, J. G., 1985, Geological Magazine 122, 649–661

Jackson, M. D., et al. 2019, Scientific Drilling 25, 35–46.
The Global Importance of Continental Seismic Sequences
Authors: Walters Richard , Craig Tim , Gregory Laura , Azad Khan Russell
Published: March 2020

Large continental earthquakes necessarily involve cascading rupture of multiple faults or segments (e.g. El Mayor-Cucapah 2010). But these same critically-stressed systems sometimes rupture in drawn-out sequences of smaller earthquakes over days or years (e.g. Central Italy 2016), instead of in a single large event. Due to the similarity in the initial conditions of both scenarios, seismic sequences may be considered as ‘failed’ multi-segment earthquakes, whereby cascading rupture is prematurely halted before all available slip deficit is released.

These two modes of strain-release have vastly different implications for seismic hazard. Recent work on the 2016 Central Italy earthquake sequence, which is the first seismic sequence to be studied with modern high-quality geodetic and seismological datasets, showed that complexity in fault structure appeared to exercise a dual control on both the timing and sizes of events throughout this sequence. However, it is unclear if this structural control is common for all continental seismic sequences, how important seismic sequences are for the global seismic moment budget, and how this contribution to moment budget may vary between different tectonic regions.

Here we select shallow crustal continental earthquakes from the Global Centroid Moment Tensor catalog, and identify seismic sequences as agglomerates of clustered pairs of earthquakes where the summed moment (M0) of all aftershocks is greater than 50% of the M0 of the first event in the sequence. We analyse the relative number of seismic sequences compared to other earthquakes for normal, reverse, and strike-slip faulting regions, and also calculate the relative M0 release of seismic sequences and other earthquakes in these three regimes.

We find that although seismic sequences are equally common by number in all continental tectonic regimes, seismic sequences account for a much higher proportion of M0 release for normal faults (~20%) than for reverse faults (~10%), with strike-slip faults intermediate between these two end-members. We also find that the proportion of M0 release in seismic sequences is higher for events that occur in regions characterised by a diversity of different earthquake types (e.g. both reverse and strike-slip faulting) than for events that occur in regions characterised by a single earthquake type (e.g. strike-slip faulting only). Together these findings imply that complexity of fault network is an important factor in controlling the occurrence of large-M0 seismic sequences, and that ‘failed’ multi-segment earthquakes and therefore large-M0 seismic sequences are more likely to occur in regions with complex fault networks.
Past changes in North Pacific (de)oxygenation – a complex interplay between water mass ventilation and organic matter respiration
Authors: Jaccard Samuel
Published: March 2020

The North Pacific basin has undergone large changes in subsurface oxygenation in the past. In general, oxygen-depleted zones increased volumetrically as climate warmed, with the rate of warming playing a critical role in determining the spatial extent of subsurface deoxygenation. The most pronounced deoxygenation episode in the upper ocean occurred midway through the deglaciation, an interval referred to as the Bolling/Allerod (B/A), associated with the reinvigoration of the Atlantic Meridional Overturning Circulation (AMOC). At this time, the upper Indo-Pacific ocean was probably less oxygenated than today. The B/A was characterized by substantial changes in intermediate water circulation, combined with efficient removal of oxygen associated with enhanced remineralization of labile organic matter, as export production increased throughout the subarctic North Pacific. The abrupt decrease in oxygenation affected large swaths of the North Pacific, including shelf environments with detrimental consequences for marine ecosystems.
This contribution will review the available paleoceanographic evidence spanning the last 3 million years and distill the salient constraints that can help better predicting the future evolution of North Pacific (de)oxygenation in the context of anthropogenic climate forcing.
Soil carbon respiration in tropical forest soils along geomorphic and geochemical gradients
Authors: Bukombe Benjamin , Kidinda Laurent , Hoyt Alison , Vogel Cordula , Bauters Marijn , Wilken Florian , Kalbitz Karsten , Fiener Peter , Doetterl Sebastian
Published: March 2020

Tropical ecosystems and the soils therein have been reported as one of the most important and largest terrestrial carbon (C) pools and are considered important climate regulator. Carbon stabilization mechanisms in these ecosystems are often complex, as these mechanisms crucially rely on the interplay of geology, topography, climate, and biology. Future predictions of the perturbation of the soil carbon pool ultimately depend on our mechanistic understanding of these complex interactions.

Using laboratory incubation experiments, we investigated if carbon release from soils through heterotrophic respiration in the African highland forests of the Eastern Congo Basin follows predictable patterns related to topography, soil depth or geochemical soil properties that can be described at the landscape scale and ultimately be used to improve the spatial accuracy of soil C respiration in mechanistic models. In general, soils developed on basalt and granite parent material (mafic and felsic geochemistry of parent material) showed significantly (p <0.05) higher specific respiration than soils developed on sedimentary rocks (mixed geochemistry) with highest rates measured for soils developed on granite. For soils developed on basalt, specific respiration decreased two-fold with soil depth, but not for soils developed on granite or sedimentary rocks. No significant differences in respiration under tropical forest were found in relation to topography for any soil and geochemical background.

Using a non-linear,  stochastic gradient boosting machine learning approach we show that soil biological, physical and chemical properties can predict the pattern of specific soil respiration (R2=0.41, p<0.05). An assessment of the relative importance of the included predictors for soil respiration resulted in 43 % of the model being driven by geochemistry (pedogenic oxides, nutrient availability), 12 % driven by soil texture and clay mineralogy, 34 % by microbial biomass, C:N, and C:P ratios and 11 % by topographic indices. 

We conclude that, in order to explain soil C respiration patterns in tropical forests, a complex set of variables need to be considered that differs depending on the local bedrock chemistry. Its effect is likely related to the varying strength of C stabilization with minerals as well as nutrient availability that might drive C input patterns and microbial turnover.
Relocation of Offshore Earthquakes around the Korean Peninsula using Multiple Seismic Arrays: Case Examples for East Sea and Yellow Sea Regions
Authors: Chiu Shu-Chioung , Chiu Jer-Ming , Kim Kwanghee , Kang Suyoung
Published: March 2020

Yellow Sea and East Sea regions near Korea are two of the most seismically active marginal seas in the Far East.  While offshore earthquakes in the Yellow Sea may be attributed to potential micro-plate boundaries, East Sea earthquakes may be associated to the seaward extension of many active faults on land or the deformation boundary between oceanic and continental crust.  However, offshore earthquake locations using local seismic network are always subjecting to large uncertainties due to poor spatial coverage of seismic stations, discrepancies on velocity models, and limitations on traditional location technologies.  For instance, it is not uncommon that the same earthquake within Yellow Sea may be reported independently more than tens to hundreds of km apart in Chinese and Korean catalogs while there is no mechanism for earthquake data exchange between the two countries.   Multiple seismic array method can be applied to improve epicenter location of offshore earthquakes.  Seismic stations in Korea can be integrated into three arrays based on their latitude. Apparent azimuths and apparent velocities of the incoming seismic waves (mainly Pn) from a regional earthquake to each array can be reliably determined.  Epicenter of a regional earthquake can thus be located by tracing seismic rays following the back azimuths derived from multiple arrays.  Offshore earthquakes in the East Sea and Yellow Sea regions are located at shallow depth within crust that Pn waves are expected to be the first arrival phase at many Korean stations.  Thus, offshore earthquakes can be reasonably located using Pn arrivals.  In the Yellow Sea case, the apparent velocity ~8.0 km/sec is observed for all arrays suggesting a typical continental Pn waves propagating across the continent-continent transition region into Korea.  In the East Sea case, the apparent velocity of ~6.8 km/sec or lower is observed for all arrays suggesting a typical oceanic Pn wave propagating across the oceanic-continental margin into Korea.  A better relocated earthquake location in the offshore region is essential for our understanding of regional tectonics and earthquake hazard assessment.
Complex Role of the Tibetan Plateau and its Surrounding Topography in the Formation of Asian Climate
Authors: Sha Yingying , Shi Zhengguo
Published: March 2020

The Tibetan Plateau (TP) has undoubtedly played an essential role in the evolution and strengthening of the coupled climate system of the Asian monsoon and inland arid climate since the Cenozoic. However, a growing number of studies have found that regional and relatively smaller scale topography also has significant impact on Asian climate.
By using high resolution atmospheric circulation model, we analyzed the effect of the main body of the TP and its surrounding topography on the evolution of Asian climate. The surrounding topography includes the Yunnan-Guizhou Plateau (YG) at the southeastern margin of the Tibetan Plateau, the Pamir Plateau (Pr) and Tian Shan mountains (TS) at the northern margin and the Mongolian Plateau (MP) further north. The results show that different from the strengthening effect of the main TP, the YG significantly weakens the Indian monsoon. With the uplift of the YG, an anomalous anticyclonic circulation appeared in the lower troposphere over the southwest, resulting in the weakening of monsoon circulation from the Bay of Bengal to the Indian subcontinent and the Arabian sea. The decline in Indian monsoon precipitation caused by the YG accounts for one-third of the total increase in precipitation caused by the entire TP.
For the arid interior Asia, the main TP, YG, Pr and TS, as well as the MP all have reduced the annual precipitation in some extent. However, different from the consistent inhibiting effect of the main TP on the precipitation over the arid interior Asia throughout the year, the decreasing effect of the YG and the MP is mainly effective in boreal winter, which is closely related to the mechanical blocking effect. In addition, the Pr and TS play a key role in the temporal and spatial differentiation of precipitation in the arid interior Asia. Before the appearance of the Pr and TS, the precipitation seasonality over the eastern sub-region was characterized with maximum rainfall in spring and winter and minimum rainfall in summer. With the uplift of Pr and TS, the precipitation over the eastern part decreases in winter and significantly increases in summer, which leads to the change of precipitation seasonality to summer dominated.
The above results indicate that different part of the extensive-third pole have different influences on the Asian monsoon and inland aridity. It suggests that the Asian monsoon-inland arid climate may have undergone complex evolutionary processes on tectonic scale.
Tracing dew and fog water inputs into temperate grassland using stable water isotopes
Authors: Li Yafei , Riedl Andreas , Aemisegger Franziska , Buchmann Nina , Eugster Werner
Published: March 2020

Dew and fog have proven to be essential water sources for plants across many Earth’s ecosystems. Under climate change with more frequent no-rain days expected in summer, the inputs of dew and fog on short-statured temperate grassland species are expected to become more important as an additional water source. In 2018, Switzerland experienced the driest April to August period of the last five decades. Our research using stable water isotopes investigates how dew and ground radiation fog affected Swiss grasslands in the extreme summer 2018 based on three intensive observation nights of dew and fog. Focusing on an intensively managed grassland located at a valley bottom close to Chamau (CH-CHA) in Switzerland, we measured the isotopic composition (δ2H and δ18O) of near-surface atmospheric water vapour with a cavity ring-down spectrometer (Picarro L2130-i), and the isotopic composition of the droplets on the leaf surface. Combining the water isotopes with eddy-covariance and meteorological measurements, we analysed the isotope dynamics and fractionation during these three dew and fog nights. Our results indicated that during dew and fog formation, water vapour δ2H and δ18O gradually decreased under saturated and even slightly supersaturated conditions, but fluctuated under unsaturated conditions. The isotopes of the sampled droplets on the leaf surfaces deviated from the expected isotopic composition based on water vapour under the equilibrium fractionation assumption. During dew and ground radiation fog nights, condensed water was a mix from two sources, atmospheric water vapour and vapour flux from the ground to the foliage. Condensation processes were accompanied by the evaporation from leaf surfaces and the diffusion in the supersaturated layer above the leaf surfaces. This caused non-equilibrium fractionation of water isotopes, seen in the fluctuation of water vapour isotopes and in the observed deviation in the sampled droplets from equilibrium liquids of water vapour. Thus, the isotopic approach is complementary to the often employed micro-lysimetric approach and helps to understand the dynamics and the sources of water vapour during dew and ground radiation fog formation.
Design water demand of irrigation for a large region using a high-dimensional Gaussian copula
Authors: Tu Xinjun
Published: March 2020

Spatial and frequency distributions of precipitation should be considered in determining design water demand of irrigation for a large region. In Guangdong province, South China, as a study case, an eight-dimensional joint distribution of precipitation for agricultural sub-regions was developed. A design procedure for water demand of irrigation for a given frequency of precipitation of the entire region was proposed. Water demands of irrigation in the entire region and its sub-regions using three design methods, i.e. equalized frequency (EF), typical year (TY) and most-likely weight function (MLW), were compared. Results demonstrated that the Gaussian copula efficiently fitted the high-dimensional joint distribution of eight sub-regional precipitation values. The Kendall frequency was better than the conventional joint frequency to analyze the linkage between the frequency of precipitation of the entire region and individual sub-regions. For given frequencies of precipitation of the entire region, design water demands of irrigation of the entire region among the MLW, EF and TY methods slightly differed, but those of individual sub-regions of the MLW and TY methods fluctuated around the demand lines of the EF method. The alterations of design water demand in sub-regions were more complicated than those in the entire region. The design procedure using the MLW method in association with a high-dimensional copula, which simulated individual univariate distributions, captured their dependences for multi-variables, and built a linkage between regional frequency and sub-regional frequency of precipitation, is recommended for design water demand of irrigation for a large region.
Performance analysis and optimization of a TByte-scale atmospheric observation database
Authors: Betancourt Clara , Schröder Sabine , Hagemeier Björn , Schultz Martin
Published: March 2020

The Tropospheric Ozone Assessment Report (TOAR) created one of the world’s largest databases for near-surface air quality measurements. More than 150 users from 35 countries have accessed TOAR data via a graphical web interface (https://join.fz-juelich.de) or a REST API (https://join.fz-juelich.de/services/rest/surfacedata/) and downloaded station information and aggregated statistics of ozone and associated variables. All statistics are calculated online from the hourly data that are stored in the database to allow for maximum user flexibility (it is possible, for example, to specify the minimum data capture criterion that shall be used in the aggregation). Thus, it is of paramount importance to measure and, if necessary, optimize the performance of the database and of the web services, which are connected to it. In this work, two aspects of the TOAR database service infrastructure are investigated: Performance enhancements by database tuning and the implementation of flux-based ozone metrics, which – unlike the already existing concentration based metrics – require meteorological data and embedded modeling.

The TOAR database is a PostgreSQL V10 relational database hosted on a virtual machine, connected to the JOIN web server. In the current set-up the web services trigger SQL queries and the resulting raw data are transferred on demand to the JOIN server and processed locally to derive the requested statistical quantities. We tested the following measures to increase the database performance: optimal definition of indices, server-side programming in PL/pgSQL and PL/Python, on-line aggregation to avoid transfer of large data, and query enhancement by the explain-analyze tool of PostgreSQL. Through a combination of the above mentioned techniques, the performance of JOIN can be improved in a range of 20 - 70 %.

Flux-based ozone metrics are necessary for an accurate quantification of ozone damage on vegetation. In contrast to the already available concentration based metrics of ozone, they require the input of meteorological and soil data, as well as a consistent parametrization of vegetation growing seasons and the inclusion of a stomatal flux model. Embedding this model with the TOAR database will make a global assessment of stomatal ozone fluxes possible for the first time ever. This requires new query patterns, which need to merge several variables onto a consistent time axis, as well as more elaborate calculations, which are presently coded in FORTRAN.

The presentation will present the results from the performance tuning and discuss the pros and cons of various ways how the ozone flux calculations can be implemented.
Extreme events Analysis of Short-Duration Rainfall and Intensity-Duration-Frequency curve using Scaling Model in North Korea
Authors: Jung Younghun , Joo Kyungwon , Lee JoonHak , Heo Jun-Haeng
Published: March 2020

Climate change has emerged as one of the defining issues of the early 21st century. Recent research confirms that the imprint of human induced climate change can be recognized in current accident events. There is a high probability of observed trends, such as increases in heat waves and heavy extreme rainfall events, intensifying over the 21st century. Extreme weather and climate events are anticipated to generate significant risks to societies and ecosystem. This paper focuses on estimation rainfall quantile using sclaling model for short duration IDF curve in North Korea. It is very important to manage the flood control facilities because of increasing the frequency and magnitude of severe rain storms. For managing flood control facilities in possibly hazardous regions, data sets such as elevation, gradient, channel, land use and soil data should be filed up. Using this information, the disaster situations can be simulated to secure evacuation routes for various rainfall scenarios. The aim of this study is to investigate and determine extreme rainfall quantile estimates in North Korea Cities using index flood method with L-moments parameter estimation. Regional frequency analysis trades space for time by using annual maximum rainfall data from nearby or similar sites to determine estimates for any given site in a homogeneous region. Regional frequency analysis based on pooled data is recommended for estimation of rainfall quantiles at sites with record lengths less than 5T, where T is return period of interest. Many variables relevant to precipitation can be used for grouping a region in regional frequency analysis. For regionalization of Han River basin, the k-means method is applied for grouping regions using variables of meteorology and geomorphology. The results from the k-means method are compared for each region using various probability distributions. In the final step of the regionalization analysis, goodness-of-fit measure is used to evaluate the accuracy of a set of candidate distributions. And rainfall quantiles by index flood method are obtained based on the appropriate distribution(GEV and GLO). Therefore, it could be possible to estimate rainfall quantiles using scale invariance and frequency analysis for Wonsan, Jangjeon, and Pyeonggang rainfall stations in North Korea. And then, rainfall quantiles based on various scenarios are used as input data for disaster simulations.

Acknowledgements

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2019R1A2C2010854).

 
Spatial variability of surface snow isotopic composition on the East Antarctic Plateau and implications for climate reconstructions
Authors: Hörhold Maria , Weinhart Alexander , Kipfstuhl Sepp , Freitag Johannes , Micha Georgia , Werner Martin , Lohmann Gerrit
Published: March 2020

The reconstruction of past temperatures based on ice core records relies on the quantitative but empirical relationship of stable water isotopes and annual mean temperature. However, its relation varies through space and time. On the East Antarctic Plateau, temperature reconstructions from ice cores are poorly constrained or even fail on decadal and smaller time scales. The observed discrepancy between annual mean temperature and isotopic composition partly relies on surface processes altering the signal after deposition but also, to a great deal, on spatially coherent processes prior to or during deposition. However, spatial coverage over larger areas on the East Antarctic Plateau is challenging. We here present in-situ measurements of the isotopic composition of surface snow with unprecedented statistical quality and coverage. 1m surface snow profiles were collected during an overland traverse between Kohnen station and Plateau Station, covering a 1200km long transect. We explore regional differences of the temperature-isotope relationship and discuss possible mechanisms affecting the isotopic composition in areas with accumulation rates lower than 60mmWEa^-1.