bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatio-temporal dynamics of reservoir (de-)commissioning in Ceará, NE Brazil
Authors: Brosinsky Arlena , Timmke Sandra , Foerster Saskia , Francke Till , Medeiros Pedro , de Araújo José Carlos
Published: March 2020

The North East of Brazil is characterized by a high spatial, seasonal and inter-annual variability of rainfall. The climate is semiarid with pronounced wet and dry seasons. In the federal state of Ceará, water supply for the dry season is ensured by the construction of reservoirs of various sizes. However, most of these reservoirs were built without documentation by the water management authorities. Thus, there is no complete state-wide inventory of reservoirs in Ceará. Using the satellite based global surface water dataset (GSW), this study aimed at investigating (i) the location, (ii) size, (iii) commissioning and decommissioning year as well as (iv) spatio-temporal dynamics of reservoirs in Ceará for the period 1984 - 2018.

Based on the maximum water extent of the GSW dataset, 17 919 reservoirs larger than 90 x 90 m were detected in Ceará (ii), which could be confirmed with an accuracy of 87 % for a validation dataset including 157 reservoirs regularly monitored by the State Agency for Meteorology and Water Resources in Ceará (FUNCEME). Thereby, reservoirs with a maximum water extent < 2.05 ha (category 1) form the largest and reservoirs with a maximum water extent > 50 ha (category 6) the smallest share in number of all detected reservoirs (i). In turn, reservoirs of category 6 contribute most to the water storage capacity while category 1 reservoirs contribute least. For the estimation of (de-)commissioning years (iii), the GSW monthly water history dataset was used. The years of commissioning and decommissioning were determined as the first and last year, respectively, of water being detected. The calculated commissioning years were validated against the FUNCEME dataset, whereas to date there is no validation data to confirm the decommissioning of reservoirs. The analysis of spatio-temporal dynamics of reservoir commissioning and decommissioning (iv) indicate a spatially variable increase of reservoirs until approximately 2010, followed by an intensive decrease until 2015 (analysis of extended study period currently ongoing).

Deviations in terms of commissioning years are mainly small and can be attributed to uncertainties inherent to satellite observations. Up to 2010, the detected spatio-temporal variability can be largely attributed to droughts which occurred in most parts of the state in several years and particularly severe since 2012. However, the maximum rate of large strategic reservoir construction by the public sector (for which records exist) decreased since the 1990’s, which is attributed to a shift in the adaptation strategy to water scarcity, from structural measures (construction of dams) to governance measures (water management and control). From the data presented here, it seems that this trend likewise occurred on the level of small reservoirs for which no records existed so far.
Late Holocene glacier and climate reconstruction from proglacial records in Vatnsdalur, northern Iceland.
Authors: Nebel Konstantin , Lane Timothy , Adamson Kathryn , Barr Iestyn , van der Bilt Willem , Kirby Jason , Hennekam Rick
Published: March 2020

The Arctic region is experiencing surface air temperature increase of twice the global average. To better understand Holocene Arctic climate variability, there is the need for continuous, high-resolution palaeoclimate archives. Sediment cores from proglacial lakes can provide such climate archives, and have the potential to record past environmental change in detail.       

Vatnsdalur, a valley in northern Iceland, hosts small, climatically sensitive cirque glaciers that became independent from the Iceland Ice Sheet after its retreat following the Last Glacial Maximum (c. 15 ka BP). Importantly, this region is located at the confluence of warm water and air masses from the south and cold polar water and air masses from the north, making it highly sensitive to North Atlantic and Arctic climate change. However, at present the region is highly understudied, lacking any high-resolution climate reconstructions.           

To address this, we combine geomorphological mapping with the first high-resolution analysis of proglacial lake sediments, to thoroughly examine northern Iceland Late Holocene environmental change.

Field mapping supplemented by high-resolution drone data was used to characterise catchment geomorphology, including seven Holocene moraines. A sediment core (SKD-P1-18) from proglacial lake Skeiðsvatn, Vatnsdalur, was analysed for sedimentological (dry bulk density, loss-on-ignition, grain size), geophysical (magnetic susceptibility) and geochemical (X-ray fluorescence core scan, 2 mm resolution) parameters.            
We identify three main sedimentary facies from these analyses, indicating variations in glacial input and catchment environmental conditions. Radiocarbon dating of lake macrofossils, supplemented by tephrochronology, provides a chronological framework. Catchment point samples, also analysed using the above analytical techniques, were used for sediment fingerprinting to disentangle non-glacial from glacial end-members.

Our results indicate the disappearance and reformation of small, climatically sensitive cirque glaciers in Vatnsdalur during the Holocene. We interpret the data to show an abrupt return to a glaciated catchment. Our results fill a geographical gap of high-resolution proglacial sediment studies in the Arctic-North Atlantic region.
Secondary Organic Aerosol Formation from On-road Gasoline Vehicles in China
Authors: Wang Hui , Tang Rongzhi , Shen Ruizhe , Yu Ying , Liu Kefan , Tan Rui , Zhang Wenbin , Zhang Zhou , Shuai Shijin , Guo Song
Published: March 2020

Organic aerosol (OA) constitutes a significant fraction of the atmospheric fine particulate matter that influences both air quality and climate. Secondary organic aerosol (SOA), which is formed through photo-oxidation of organic vapors in the atmosphere, is a major component of OA. There are some studies indicating the major role of vehicles emissions in SOA formation in urban cities of China. However, SOA formation is complex and uncertain.

Historically, the China fleet has been dominated by vehicles equipped with port-fuel injected (PFI), but the market share of vehicles equipped with gasoline direct injection engines (GDI) has increased dramatically. And 10% of renewable energy ethanol (E10) may be added to the gasoline of China market in the future. Go-PAM is one kind of potential aerosol mass for simulating SOA formation, which is designed and made by the University of Gothenburg.

In this study, we focus on the influence of ethanol content (0% or 10%), engine types (GDI or PFI) and different engine loads (idling or constant velocity) to the SOA formation potential from gasoline motor cars emissions. We exposed the diluted emissions to a range of oxidation (O3 and OH) concentrations in the Go-PAM, resulting different OH exposures. We observed variations of different cases in SOA formation.

Firstly, compared to PFI engine, GDI engine at idling loading has larger SOA mass concentrations. The peak SOA production of PFI engine at idling load occurred at equivalent photochemical age (EPA) of 3.8 days, which peak point occurred at larger EPA (4.8 days) for GDI engines. Secondly, there is no large difference between E10 and gasoline. Thirdly, OA enhancement is more obvious at idling (about 30-180 times) than at constant velocity (about 3-4 times) whatever engine is used. Generally, densities of particles at size of 70nm,140nm and 200nm keep growing from about 1.25 up to 1.45 g/cm3.

The results of this study highlight the utility of Go-PAM for studying SOA formation potential from vehicle exhaust, and provide indications of the influence of ethanol content and different engines to SOA formation in China.
The impact of large-scale winds on thermally driven flows and exchange processes over mountainous terrain
Authors: Weinkaemmerer Jan , Bašták Ďurán Ivan , Schmidli Jürg
Published: March 2020

In the convective boundary layer over mountainous regions, the mean values and the fluxes of quantities like heat, mass, and momentum are strongly influenced by thermally induced flows. Several studies have pointed out that the enhanced warming of the air inside a valley can be explained by the valley-volume effect whereas the cross-valley circulation leads to a net export of heat to the free atmosphere. We are interested in the influence of an upper-level wind on the local circulations and the boundary-layer properties, both locally and in terms of the horizontal mean, as this aspect has not yet received much attention. LES are carried out over idealized, two-dimensional topographies using the CM1 numerical model. For the analysis, turbulent, mean-circulation, and large-scale contributions are systematically distinguished. Also, budget analyses are performed for the turbulence kinetic energy and the turbulent heat and mass flux. Based on the first results for periodic topographies, no crucial influence on the horizontally averaged heat-flux and temperature profile can be observed, even though the flow pattern of the thermal wind is qualitatively changed. In addition to that, the impact on moisture transport will be evaluated and simulations over different topographies as well as for different atmospheric conditions and surface properties will be presented.
Wind waves modeling in the polar law weather conditions
Authors: Kuznetsova Alexandra , Poplavsky Evgeny , Rusakov Nikita , Troitskaya Yuliya
Published: March 2020

Arctic storms pose a great danger to developing commercial and passenger shipping, coastal infrastructure, and also for oil production from offshore platforms. This is primarily due to high waves and extreme winds. Such episodes of adverse weather conditions due to their rapid development are poorly predicted by modern models. For this purpose, the representation of the event of polar law is studied in the wave model WAVEWATCH III.

Wind waves were simulated under conditions of polar depression on ice-free water. To simulate wind waves under conditions of polar depression, the Barents Sea was selected, where, according to the data of [1, 2], a large number of polar hurricanes are observed. Among the identified polar hurricanes, for example, in [3], a hurricane that took place on 05.02.2009, observed at coordinates 69 N 40 E is chosen. The preliminary results in the wave model are obtained without the ice influence consideration. The developed model was configured using the CFSR wind reanalysis data. The resulting distribution of significant wave heights is obtained. Then, to consider the attenuation by sea ice, the reanalysis data of the Arctic System Reanalysis Version 2 (ASRv2), which is based on Polar WRF with a resolution of 15 km for the Arctic region, is used. Modeling the destruction of ice by waves during an intense arctic storm will be implemented using WW3 models with an IS2 module.

The work is supported by RFBR grant 18-05-60299.

Smirnova, J. E., Golubkin, P. A., Bobylev, L. P., Zabolotskikh, E. V., & Chapron, B. (2015). Polar low climatology over the Nordic and Barents seas based on satellite passive microwave data. Geophysical Research Letters, 42(13), 5603-5609.

Smirnova, J., & Golubkin, P. (2017). Comparing polar lows in atmospheric reanalyses: Arctic System Reanalysis versus ERA-Interim. Monthly Weather Review, 145(6), 2375-2383.

Noer, G., & Lien, T. (2010). Dates and Positions of Polar lows over the Nordic Seas between 2000 and 2010. Norwegian Meteorological Institute Rep.
Differences of Hemorrhagic and Ischemic Strokes in Age Spectra and Responses to Climatic Thermal Conditions
Authors: Ma Pan
Published: March 2020

The risks of Emergency Room (ER) visits for cerebral infarction (CI) and intracerebral hemorrhage (ICH) is found to differ in different age groups under different climatic thermal environments. Based on CI and ICH related ER-visit records from three major hospitals in Beijing, China, from 2008 to 2012, the advanced universal thermal climate index (UTCI), was adopted in this study to assess the climatic thermal environment. Particularly, daily mean UTCI was used as a predictor for the risk of ER visits for CI and ICH. A generalized quasi-Poisson additive model combined with a distributed lag non-linear model was performed to quantify their association. The results indicated that (ⅰ) the highest growth rate of ER visits for ICH occurred in age 38 to 48, whereas an increasing ER admissions for CI maintained at age 38 to 78. (ⅱ) The frequency distribution of UTCI in Beijing peaked at -8 and 30 ℃, corresponding to moderate cold stress and moderate heat stress, respectively. (ⅲ) Correlation analysis indicated that ICH morbidity was negatively correlated with UTCI, whereas occurrence of CI showed no significant association with UTCI. (ⅳ) The estimated relative risk of ER visits corresponding to 1℃ change in UTCI, which was then stratified by age and gender, indicated that all sub-groups of ICH patients responded similarly to thermal stress. Namely, there is an immediate ICH risk (UTCI = -13℃, RR=1.35, 95% CIs: 1.11~1.63) from cold stress on the onset day, but non-significant impact from heat stress. As for CI occurrences, no effect from cold stress was identified, except for only those aged 45 to 65 were threatened by heat stress (UTCI = 38℃, RR=1.64, 95% CIs: 1.10~2.44) on lag 0~2d. 
Geophysical imaging of permafrost in the SW Svalbard – the result of two high arctic expeditions to Spitsbergen
Authors: Majdanski Mariusz , Marciniak Artur , Owoc Bartosz , Dobiński Wojciech , Wawrzyniak Tomasz , Osuch Marzena , Nawrot Adam , Glazer Michał
Published: March 2020

The Arctic regions are the place of the fastest observed climate change. One of the indicators of such evolution are changes occurring in the glaciers and the subsurface in the permafrost. The active layer of the permafrost as the shallowest one is well measured by multiple geophysical techniques and in-situ measurements.

Two high arctic expeditions have been organized to use seismic methods to recognize the shape of the permafrost in two seasons: with the unfrozen ground (October 2017) and frozen ground (April 2018). Two seismic profiles have been designed to visualize the shape of permafrost between the sea coast and the slope of the mountain, and at the front of a retreating glacier. For measurements, a stand-alone seismic stations has been used with accelerated weight drop with in-house modifications and timing system. Seismic profiles were acquired in a time-lapse manner and were supported with GPR and ERT measurements, and continuous temperature monitoring in shallow boreholes.

Joint interpretation of seismic and auxiliary data using Multichannel analysis of surface waves, First arrival travel-time tomography and Reflection imaging show clear seasonal changes affecting the active layer where P-wave velocities are changing from 3500 to 5200 m/s. This confirms the laboratory measurements showing doubling the seismic velocity of water-filled high-porosity rocks when frozen. The same laboratory study shows significant (>10%) increase of velocity in frozen low porosity rocks, that should be easily visible in seismic.

In the reflection seismic processing, the most critical part was a detailed front mute to eliminate refracted arrivals spoiling wide-angle near-surface reflections. Those long offset refractions were however used to estimate near-surface velocities further used in reflection processing. In the reflection seismic image, a horizontal reflection was traced at the depth of 120 m at the sea coast deepening to the depth of 300 m near the mountain.

Additionally, an optimal set of seismic parameters has been established, clearly showing a significantly higher signal to noise ratio in case of frozen ground conditions even with the snow cover. Moreover, logistics in the frozen conditions are much easier and a lack of surface waves recorded in the snow buried geophones makes the seismic processing simpler.

Acknowledgements               

This research was funded by the National Science Centre, Poland (NCN) Grant UMO-2015/21/B/ST10/02509.
Effects of temperature and water stress on agricultural productivity in a semi-arid irrigation system under changing climate
Authors: Becker Rike , Schulz Stephan , Merz Ralf , aus der Beek Tim , Schüth Christoph
Published: March 2020

The study focuses on the assessment of climate change impacts on the water balance and agricultural productivity in a semi-arid, meso-scale irrigation system, in Punjab, Pakistan.

To simulate potential future water balance changes in our intensively irrigated agricultural study area, we chose the widely used Soil & Water Assessment Tool (SWAT) model software. Using the SWAT model, we were able to incorporate detailed irrigation management strategies into the analysis, and to account for spatially distributed plant physiognomic dynamics and their effects on the local water balance.

Climate change data is taken from the Coordinated Regional Climate Downscaling Experiment (CORDEX; www.cordex.org), which provides a suite of regional climate projections based on Global Climate Models of the Coupled Model Intercomparison Project, Phase 5 (CMIP5). We take into account medium (RCP 4.5) and high (RCP 8.5) greenhouse gas emission scenarios from the IPCC - Fifth Assessment Record (AR5) and study their short (until 2030) and medium term (until 2050) impacts.

The assessment shows the following interesting results regarding climate change impacts on future agricultural productivity in our study area:

Temperature stress on plant growth will increase significantly

A substantial reduction in future summer crop yields can be expected

Temperature stress induces the reduction of biomass production, which causes a decrease in transpiration and hence a decrease in actual evapotranspiration

Reduced transpiration counteracts the temperature-induced increase in potential evapotranspiration, which leads to surprisingly low increases in future irrigation water demand despite the significant warming

Temperature stress related adaption strategies (e.g. more heat tolerant crops) are under these circumstances more important than increasing irrigation efficiency

Even though overall changes in water demand are surprisingly low, higher pressures on surface water and groundwater resources can be expected due to changes in plant growing cycles: Future temperature patterns are expected to speed up the plant growing cycle and increase irrigation demands during the early growing stages. In our study area, this alters the share of irrigation water supply sources (i.e. rain, surface water and groundwater) and leads to higher demands of surface water and particularly groundwater resources, while rainfall contributions decrease.

The study discusses the above mentioned climate change impacts and their interaction. It focuses on the importance of temperature vs. water stress, and elaborates on their implications for potential climate adaption strategies.
The nature of the North-South change of the magnitude of tectonic shortening in Central Andes at Altiplano-Puna latitudes: a thermomechanical modeling approach.
Authors: Pons Michaël , Sobolev Stephan
Published: March 2020

The Andean orogeny is a subduction-type orogeny, the oceanic Nazca Plate sinks under the continental South American Plate. While the subduction has been active since ~180 Ma, the shortening of the Andes initiated at ~50 Ma or less.

In a oceanic-continental subduction system, the absolute velocity of the overriding-plate (OP) largely controls the style of subduction (stable, advancing, retreating), the geometry of the slab (dipping angle, curvature) and the style of deformation (shortening or spreading) within the OP. In the case of the Central Peru-Chile subduction, the South American plate is advancing westwards whereas the Nazca plate is anchored into the transition zone (~660 km). As a consequence, the trench is forced to retreat and the Nazca plate to roll-back. The dip of the slab decreases meanwhile the Andes experienced a maximum shortening of ~300 km at ~19-21°S latitudes.

Previous study have shown that the strain localizes within areas of low strength and low gravitational potential of energy. In central Andes, weakening mechanisms of the OP such as lithospheric delamination have intensified the magnitude of tectonic shortening and contributed to formation of the Altiplano-Puna plateau. The deformation between the plateau and the foreland occurs in the form of pure shear or simple shear and is expressed in terms of different tectonic styles in the foreland basin, thick-skinned (e.g the Puna) and thin-skinned (e.g the Altiplano), respectively. Nevertheless, the influence of the strength variations of the OP on the subduction dynamics in the case of the central Andes has been poorly explored so far. Our hypothesis is that lateral variations of OP strength result in variable rates of trench roll-back. To test it, we have built 2D high-resolution E-W cross sections along the Altiplano and Puna latitudes (12-27°S) including the subduction of the Nazca plate. For that purpose, we used the FEM geodynamic code ASPECT. Our model includes visco-plastic rheology in addition to gabbro-eclogite phase transition. These preliminary results contribute to the discussion on the nature of the magnitude of shortening in a subduction system. They are also a first step to derive a 3D model of the entire region and to consider additional surface processes such as erosion, transportation and sedimentation.
The effect of garnet and muscovite on the recrystallized grain size of quartz from general shear experiments
Authors: Tokle Leif , Hirth Greg , Morales Luiz , Stunitz Holger
Published: March 2020

To investigate the role of strong and weak secondary phases on the recrystallized grain size of quartz, we performed grain size analyses on quenched samples from general shear experiments on quartz-garnet and quartz-muscovite mixtures. Six general shear experiments were conducted in the Griggs apparatus; three with mixtures of quartz-garnet (vol.% garnet 5, 15, 30) and three with mixtures of quartz-muscovite (vol.% muscovite 5, 10, 25). The starting powders for both set of experiments were synthetic mixtures of quartz-muscovite or quartz-garnet with 0.1 wt.% water added. The quartz-garnet experiments were conducted at 900°C, a pressure of 1.2 GPa, and a shear strain rate of ~10-5 s-1, while the quartz-muscovite experiments were conducted at 800°C, a pressure of 1.5 GPa, and a shear strain rate of ~10-5 s-1. At these deformation conditions quartz is stronger than muscovite and weaker than garnet. We observed that the bulk strength of the aggregate decreases with a greater volume percent of muscovite and increases with a greater volume percent of garnet. Garnet at these conditions does not deform plastically. The presence of secondary phases within the deforming aggregate causes stress concentrations and partitioning of strain rate between the different phases relative to the measured bulk stress and strain rate. The degree of partitioning is primarily related to the rheology and volume percent of the phases. Due to the piezometric relationship between recrystallized grain size and stress, we can use the quartz recrystallized grain size to determine the local stress of quartz in the experiments and compare it to the measured bulk stress. The results from these analyses will provide new insight into the effect of strain partitioning in general and of strong and weak secondary phases on quartz rheology.
Soft rock cliff retreat under changing climate drivers
Authors: Spencer Thomas , Brooks Susan
Published: March 2020

Shoreline retreat can happen rapidly in cliffs composed of loosely consolidated glacial and pre-glacial sediments. Typical centennial-scale average retreat rates for some cliffed coastlines of East Anglia, UK are 2 - 5 m a-1 where cliffs have no protection from storm energetics. Recent research using pre- and post-storm clifftop (geomorphological) surveys, as well as aerial photographs, has shown that in single events retreat can be 3 – 4 times the long-term average, with up to 15 m of retreat in a single event. Periods of clifftop stasis are thus interspersed with short term shocks, when meteorological conditions generate energetic drivers of change (elevated still water levels, high onshore waves, high rainfall inputs). Furthermore, short term shocks deliver enhanced sediment supply to the nearshore region, which is an important factor to take into account within future management planning strategies.  

This paper uses the latest Earth Observation data to quantify and evaluate rates of soft rock cliff retreat, thereby identifying periods when short term shocks have been delivered to the cliffs. It then explores the climate drivers of these shocks and assesses the associated synoptic meteorological scenarios. Finally it considers the implications for quantities of sediment released, in terms of both overall magnitude and alongshore variability.

Results suggest that three recent events stand out as having a significant impact on rates of cliff retreat and associated sediment release on the Suffolk coast, southern North Sea. The “Big Freeze” of the UK winter of 2010-11 involved a protracted period of easterly air flow from mid-November and into December, 2010. The process drivers were high magnitude onshore winds, generating nearshore waves of around 4 m. The 5 December 2013 North Sea surge similarly resulted in rapid cliff retreat and sediment release. In this event winds were alongshore so the wave impacts were lower, but the elevated water levels generated by the surge meant that wave action could be directed onto the cliffs. By far the biggest recent event in terms of storm forcing energetics was the February – March 2018 “Beast from the East” and “Mini Beast”, where persistent onshore winds generated waves of almost 4.5 m at Southwold Approaches (highest on record) that coincided with two phases of high spring tides (no surge). When regional-scale Sudden Stratospheric Warming (SSW) generates strong and persistent easterly winds there are widespread potentially irreversible consequences for cliff and beach sediments around the western North Sea coastline.
Tillage and cropping effects on soil organic carbon: biodegradation and storage in density and size fractions
Authors: Zhang Yan
Published: March 2020

Improvements in management practices can prevent the decline of soil organic carbon (SOC) storage caused by conventional tillage practice in Northeast China. Density and size fractionation can track the transformation of plant residue into SOC and its location in soil matrix. We used a long-term field study in China to evaluate these changes as a result of improved management involving tillage and cropping systems. Experimental treatments included no-till (NT) and moldboard ploughing (MP) under monoculture maize (Zea mays L.) (MM) and maize-soybean (Glycine max Merr.) rotation (MS); these were compared to the traditional management involving conventional tillage (CT) under MM. An incubation study was conducted to evaluate mineralization and the biodegradability of SOC. The soils were also physically fractionated by density (light fraction, LF) and size (sand, silt, clay). With improved management, the SOC storage in the clay showed the largest increase across all fractions. This increase was greater for MS than MM. The NTMS treatment resulted in a decline in silt-OC storage compared to CTMM. The SOC mineralization (mg CO2-C g-1 soil) was affected by tillage and driven by LF-OC and was observed in the order: NTMM (2.06) > MPMM (1.72) ≈ NTMS (1.71) > CTMM (1.52) ≈ MPMS (1.41). Both cropping and depth affected the biodegradability of SOC. Considering the plough layer (0-20 cm), treatments under MM had larger proportion of biodegradable SOC than under MS. We conclude that the significant differences in SOC storage in physical fractions and SOC biodegradation were caused by differences in soil management.
Boron isotope analysis of coral skeletons by laser ablation MC-ICP-MS: new insights into calcification and environmental reconstruction at high temporal resolution
Authors: Foster Gavin L. , Chalk Thomas B. , Standish Christopher D.
Published: March 2020

Despite being some of the largest bio-constructions on the planet, coral reefs are made by many millions of cm- to mm-sized polyps of Scleractinian corals. Calcification occurs in a micron sized space sandwiched between the coral animal and the existing skeleton, known as the extra cellular medium (ECM). The coral animal has a tight control on the carbonate system in this space through deploying enzymatic pumps (e.g. Ca-ATPase) and secreting acidic-rich proteins. Tracking the state of the carbonate system in the ECM is therefore key to forming a mechanistic understanding of how environmental change, such as ocean acidification, influences skeletal formation and ultimately the growth and resilience of these important ecosystems.

Traditional means to examine ECM composition is through the use of micro-electrodes. While these approaches have revealed many key insights they are, by their nature, invasive.  They also only provide snap shots of information for corals grown in the laboratory. The boron isotopic composition of the coral skeleton and its boron content (expressed as B/Ca ratio) have recently emerged as a viable alternative approach to fully characterise the carbonate system in the ECM.  However, most studies employ bulk sampling techniques which require averaging across both structural elements of the coral skeleton and many months to years of growth. Laser ablation MC-ICP-MS approaches are now available as an alternative sampling protocol (e.g. Standish et al. 2019), and along with B/Ca (and other trace element) measurements this not only allows a reconstruction of the full carbonate system of the ECM from an analysis of the skeleton of any coral (cultured or wild) at unprecedented spatial and temporal resolution, but it also allows an examination of the influence of the carbonate system in the ECM on trace element incorporation. 

Here we present boron isotope and trace element analyses of several tropical, reef-building, corals to examine the nature and magnitude of fine scale variation in ECM composition.  By studying corals from locations where external seawater is well known we also gain insights into trace element incorporation and whether external seawater pH can be accurately reconstructed from the boron-based proxies at weekly (or better) resolution. 

 

Standish, C.D., Chalk, T.B., Babila, T.L., Milton, J.A., Palmer, M.R., Foster, G.L. (2019) The effect of matrix interferences in situ boron isotope analysis by laser ablation MC-ICP-MS, Rapid Communications in Mass Spectrometry 33: 959–968 https://doi.org/10.1002/rcm.8432
MOSMIX-SNOW – A Model Output Statistics Product for Fresh Snow Forecasts at Mountain Locations
Authors: Lambert Andreas , Trepte Sebastian , Ehrnsperger Franziska
Published: March 2020

Many Numerical Weather Prediction (NWP) models provide the parameter total snow depth as a Direct Model Output (DMO) surface variable. In mountain regions, however, the orographic flow modification significantly influences precipitation formation and preferential settling, leading to large model biases if DMO is directly compared to fresh snow point observations. Avalanche risk forecasts in turn require calibrated deterministic and probabilistic fresh snow forecasts, as the amount of fresh snow constitutes a crucial driver of avalanche risk.

In this study, MOSMIX-SNOW, a Model Output Statistics (MOS) product based on multiple linear regression is developed. Ground-based observations and operational forecast data of the two deterministic global NWP models ICON and ECMWF form the basis of the MOS system. MOSMIX-SNOW offers point forecasts for 20 deterministic as well as probabilistic forecast variables like the amount of fresh snow within 24h, the probability of more than 30cm of fresh snow within 24h and some basic variables like 2m temperature and dew point. The unique characteristic of MOSMIX-SNOW is the large number of observation-based, model-based and empirical predictors, which exceeds 200. Furthermore, a long historical data period of 9 years is applied for training of the MOS system. Thus, local orographic effects and large scale flow patterns are implicitly included in the MOS equations by a location and lead time specific choice of predictors. To avoid unrealistic jumps in the forecast, persistence predictors, which represent the forecast value of the previous forecast hour, are included in the MOS system. All forecasts feature a maximum lead time of +48h, have an hourly forecast resolution as well as update cycle and are available for about 15 mountain locations in the Bavarian Alps between 1100m and 2400m above sea level.

The verification analysis of the winter season 2018/19 shows that MOSMIX-SNOW forecasts offer a significantly higher forecast reliability than the raw ensemble of the regional NWP model COSMO-D2-EPS. The bias of the deterministic forecast parameters is smaller for MOSMIX-SNOW, especially for heavy snowfall events. MOSMIX-SNOW turned out to be a useful tool to support the avalanche risk forecasts on a daily basis during the snowy winter of 2018/19. Furthermore, the deterministic fresh snow forecast of MOSMIX-SNOW and other meteorological parameters like 2m-temperature serve as input for operational snowpack simulations. Measurement related noise and snow drift in the observations, however, are identified as an important source of uncertainty and the application of noise reduction techniques like a Savitzky-Golay filter are expected to have a beneficial impact on the forecast quality. MOSMIX-SNOW will become operational by end of 2020.
Soil formation and biological soil crust development in glacier forelands of Svalbard (High Arctic)
Authors: Gries Philipp , Schmidt Karsten , Kühn Peter , Eberle Joachim , Seitz Steffen , Scholten Thomas , Węgrzyn Michał , Wietrzyk-Pełka Paulina
Published: March 2020

Over the last decades, a progressive glacier melting has been detected induced by climate change which cause a rapid enlargement of ice-free areas in glacier forelands in Arctic, Antarctic and Alpine regions. These recently deglaciated areas represent highly dynamic environments in terms of vegetation development and soil formation. Tundra plant communities of glacier forelands mainly consist of cryptogamic species forming biological soil crusts (BSCs) on the surface. These BSCs are known to promote the accumulation of aeolian particles and organic material being relevant to soil formation. It is important to understand both BSC development and soil formation in glacier forelands as fundamental to future development of mature tundra which contributes to an increase in soil organic carbon (SOC) and nitrogen (N) stocks in soil. The heterogeneous terrain of glacier forelands affects the spatial variation in both soil and vegetation characteristics which are additionally influenced by the distance to the glacier terminus. This study focuses on the spatial variation in soil and BSC characteristics in Arctic glacier forelands of Svalbard using multi-scale contextual soil mapping (CSM) and Euclidean distance fields (EDF). The data set comprises of soil (SOC, N, texture) and BSC characteristics (species composition, percent cover) from 168 sampling locations as well as terrain covariates (elevation, slope, aspect, curvature) at several scales using CSM and spatial covariates (EDF). Random forests (RF) are used to analyse the relationships between the covariates and soil and BSC characteristics, respectively.

Preliminary results show a good quality of the RF models (R²/RMSE) which is similar for SOC (0.41/6.19) and N (0.44/0.22). Elevation, curvature and slope at large scales are the most important covariates to explain the spatial variation in SOC and N. On large scales, these covariates represent the distance to the glacier terminus and generally explain the increase in SOC and N with increasing distance from the glacier terminus.  Additionally, elevation at small scales represents relevant issues of predominant geomorphologic features signature (e.g. moraine topography) to soil formation and BSC development. Analyses of the spatial variation and interrelationships of soil and BSC characteristics are still ongoing and further results will be presented at EGU 2020.
IGS RTS for real-time global ionospheric total electron content modeling: Method and Applications
Authors: Wang Ningbo , Li Zishen , Wang Liang
Published: March 2020

To enable GNSS applications with low or no time latency, real-time services (RTS) of the International GNSS Services (IGS) has been launched since 2013. The IGS RTS provides real-time data streams with latencies of less than few seconds, containing multi-frequency and multi-constellation GNSS measurements from a global network of high-quality GNSS receivers, which provides the opportunity to reconstruct global ionospheric models in real-time mode. For the computation of real-time global ionospheric maps (RT-GIM), a 2-day predicted global ionospheric model is introduced along with real-time slant ionospheric delays extracted from real-time IGS global stations. GPS and GLONASS L1+L2, BeiDou B1+B2 and Galileo E1+E5a signals with a sampling rate of 1 Hz are used to extract slant TEC (STEC) estimates. Spherical harmonic expansion up to degree and order 15 is employed for global vertical TEC (VTEC) modeling by combining the observed and predicted ionospheric data in real-time mode. Real-time ionospheric State Space Representation (SSR) corrections are then distributed in RTCM 1264 message (123.56.176.228:2101/CAS05) aside from the generation of RT-GIM in IONEX v1.0 format (available at ftp://ftp.gipp.org.cn/product/ionex/). The quality of CAS RT-GIMs is assessed during an 18-month period starting from August 2017, by comparison with GPS differential slant TECs at the selected IGS stations over continental areas, Jason-3 VTECs over the oceans and IGS combined final GIMs on a global scale, respectively. Results show that CAS’s RT-GIM products exhibit a relative error of 13.9%, which is only approximately 1-2% worse than the final ones during the test period. Additionally, the application of RT-GIM on the single-frequency precise point positioning (PPP) of smartphones is also presented.
Spatial Patterns of Storm-Induced Landslides and Their Relation to Past Extreme Rainfall
Authors: Marc Odin , Gosset Marielle , Saito Hitoshi , Uchida Taro , Malet Jean-Philippe
Published: March 2020

Storm-induced landslides are a common hazard, but the link between their spatial pattern and rainfall properties is poorly understood, mostly because hillslope stability is modulated by under-constrained, spatially variable topographic, hydrological and mechanical properties.

Here, we use a 26 years long, high spatial resolution rainfall dataset from the Japanese radar network, to analyze the landslide pattern (1900 landslides within ~5000 km2) caused by Typhoon Talas (>1500 mm in 3 days) in 2011 in the Kii Peninsula. We show that it poorly correlates with the rainfall amount accumulated during the event over short to long timescales (1-72h), but agrees well with the rainfall anomaly (i.e., the event rainfall amount over the rainfall amount expected for a 10-year return period rainfall). Normalizing the event rainfall by mean annual or seasonal rainfall does not match as well the landslide pattern. This suggests that the variability in hillslope properties has co-evolved with the recent climate, where slopes exposed to stronger extreme rainfall have experienced higher landslide rates until their properties (e.g., regolith thickness, strength and permeability) have reached an equilibrium. In this framework, the 10-year return rainfall amount would be a proxy for hillslope properties, and we show that it allows an improved prediction of the landslide pattern when coupled with rainfall amount and slope. Finding ways to constrain the spatial variability of these parameters to test this hypothesis is an exciting challenge.

Last we note that rock-types seem to respond to rainfall anomalies at various timescales, favoring specific landslide geometries, and suggesting various hydrological properties in these zones. Specifically, a coastal area underlain by highly weathered volcanic rocks yielded a high landslide density with a high proportion of debris flow, correlating with the 2h anomaly while the rest of the landslides matches best the 48h anomaly.

Although such influence of lithology on hydrological behavior remains hard to predict, we propose the computation of rainfall anomalies for multiple timescales to pave the way towards operational landslide forecasts in case of large storms. More generally, regional landslide susceptibility maps may also be significantly enhanced by considering maps of past extreme rainfall.
GRAVL: a new satellite mission concept aiming to detect earthquakes with a magnitude of 6.5 Mw and higher
Authors: Woodwark Jerome , Stefko Marcel ,   GRAVL development team
Published: March 2020

Data from the US and German Gravity Recovery And Climate Experiment (GRACE) showed indications of pre-, co-, and post-seismic mass redistributions associated with earthquakes down to a magnitude of 8.3 Mw. These demonstrated state-of-the-art capabilities in obtaining high spatial resolution space-based gravimetry, and helped to improve understanding of mantle rheology, potentially even providing a route to developing early warning capabilities for future seismic events. We describe a new mission concept, GRAvity observations by Vertical Laser ranging (GRAVL), which aims to extend the earthquake detection limit down to magnitude 6.5 Mw, significantly increasing the number of observable events.

GRAVL directly measures the radial component of the acceleration vector via “high-low” inter-satellite laser ranging, increasing gravity field sensitivity. A constellation of Low-Earth Orbit (LEO) satellites act as test masses, equipped with reflectors and high precision accelerometers to account for non-gravitational forces. Two or more larger satellites are placed above these, in Geostationary or Medium Earth Orbit (GEO / MEO), and measure the distance to the LEO satellites via time-of-flight measurement of a laser pulse. To do this, the GEO/MEO spacecraft are each equipped with a laser, telescope and detector, and additionally require highly  accurate timing systems to enable ranging accuracy down to sub-micron precision. To detect co-seismic mass redistribution events of the desired magnitude, we determine a gravity field measurement requirement of order 0.1 µGal at a spatial resolution of approximately 100 km over a 3-day revisit interval. These are challenging requirements, and we will discuss possible approaches to achieving them.

The GRAVL mission concept was developed during the FFG/ESA Alpbach Summer School 2019 by a team of science and engineering students, and further refined using the Concurrent Engineering approach during the Post-Alpbach Summer School Event at ESA Academy's Training and Learning Facility at ESEC-Galaxia in Belgium.
Cost-Effective Air Quality Monitoring System Based on an Open-Source Electronics Platform for Three-Dimensional Atmospheric Environmental Data Collection
Authors: Tung Yi-Chung , Chang Dao-Ming , Kuo Chuang-Yuan
Published: March 2020

Air pollution and extreme weather patterns have become serious issues over the world, especially in highly urbanized areas.  In order to detailed study the atmospheric environmental change, the capability to perform high spatiotemporal resolution atmospheric environmental data collection is highly desired.  In this research, we develop a cost-effective air quality monitoring system based on as open-source electronics platform (Arduino Uno Rev3) with multiple environmental sensing modules including particulate matter (PM) concentration, temperature, humidity, and sound sensors.  An integrated monitoring system with one weather station (precipitation and wind sensors) and two sets of environmental sensors set up in different heights from the ground costs less than USD$300.  The entire system is powered by a battery for portability, and all the data can be stored in a secure digital (SD) memory card for long-term monitoring. The cost-effectiveness makes it feasible for large-scale field tests with three-dimensional (3D) spatial resolution.  In the experiments, the system is tested in urban areas, and the data collection performance has been confirmed.  The results show that the data with single minute resolution can be successfully achieved in real-world scenarios with high air temperature (> 38oC) and rain conditions for more than 65 hours with a single-time battery setup.  In addition, the data collected from different heights have shown distinct atmospheric environmental patterns suggesting that it is critical to perform 3D high spatiotemporal measurement and modeling for city-scale studies.
HO2 enhancements due to sprite discharges - observations and model simulations
Authors: Winkler Holger , Yamada Takayoshi , Kasai Yasuko , Notholt Justus
Published: March 2020

We present first observational evidences of an HO2 production in the mesosphere above sprite‐producing thunderstorms derived from low‐noise SMILES (Submillimeter-Wave Limb-Emission Sounder) observation spectra in relation with sprite detections by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) instrument. Three events were identified with enhanced HO2 levels of approximately 1025 molecules at altitudes of 75-80 km a few hours after sprite occurrence. These first direct observations of chemical sprite effects are compared to results of plasma chemistry model simulations of electrical discharges in the mesosphere, and processes which can lead to an increase of mesospheric HO2 on timescale of a few hours after a sprite event are analysed.
Influence of Atmospheric Teleconnections on Interannual Variability of Boreal Fires
Authors: Zhao Zhiyi , Lin Zhongda , Li Fang
Published: March 2020

Wildfires are common in boreal forests around the world and strongly affect regional ecosystem processes and global carbon cycle. Previous studies have suggested that local climate is a dominant driver of boreal fires. However, the impacts of large-scale atmospheric teleconnection patterns on boreal fires and related physical processes remain largely unclear. This study investigates the influence of nine leading atmospheric teleconnection modes and El Niño-Southern Oscillation (ENSO) on the interannual variability of simultaneous summer fires in the boreal regions based on 1997-2015 GFED4s burned area, NCEP/NCAR atmospheric reanalysis, and HadISST sea surface temperature. Results show that ENSO has only a weak effect on boreal fires, distinct from its robust influence on the tropical fires. Instead, the interannual variability of burned area in the boreal regions is significantly regulated by five teleconnection patterns. Specifically, East Pacific-North Pacific (EP/NP) and East Atlantic/West Russia (EA/WR) patterns affect the burned area in North America, North Atlantic Oscillation (NAO) and East Atlantic (EA) patterns for Asia, and the Pacific-North American (PNA) pattern for Europe. Related to the teleconnections, the larger burned area is attributable to warmer surface by an anomalous high-pressure above and drier surface due to less moisture transport from the neighboring oceans. The results improve our understanding of driving forces of interannual variability of boreal fires and then regional and global carbon budgets.