bluuebunny/crossref_metadata_2025 huggingface dataset:
Cleaning magnetometer data using multi sensor configuration
Authors: Constantinescu Dragos , Auster Hans-Ulrich , Delva Magda , Hillenmaier Olaf , Magnes Werner , Plaschke Ferdinand
Published: March 2020

Measuring the in situ magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometers sensors at a large distance from the spacecraft body. This significantly drives up the costs and time for building the spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removing of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program.

The Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean Geostationary Satellite GEO-KOMPSAT-2A (GK-2A) uses for the first time a multi-sensor configuration for onboard data cleaning. To remove the AC disturbances, a combination of the measurements from sensors placed at different positions from the disturbance sources is processed onboard. Sensor biases due to daily temperature variations are also removed using the specific SOSMAG sensor arrangement. 

 
ENSO and TWC: a multi-model evaluation
Authors: Pivotti Valentina , Cherchi Annalisa , Bellucci Alessio , Anderson Bruce
Published: March 2020

Previous research has extensively established that, during the last decades, the Trade Wind Charging (TWC) mechanism is a fundamental precursor of El Niño Southern Oscillation (ENSO). Moreover, recent results suggest that its relevance as an ENSO driver varies when a longer time interval is included the analysis. This article investigates whether TWC is isolated as a significant ENSO precursor; and how the internal variance of their coupling behaves, on a CMIP6 multi model ensemble. In particular, we consider the models participating to the CMIP6 HigResMIP, specifically designed to investigate the role that model resolution plays in simulating climate processes. For each model, we have included in the analysis 100-year long integrations of the present climate that are forced with constant radiative forcing representative of the 1950s at standard and enhanced resolutions.

The analysis follows two steps for each experiment. First, through a combination of Empirical Orthogonal Function (EOF) and Canonical Correlation Analysis (CCA) it isolates ENSO and TWC. Then, in order to study their mutual relation, the combination of EOF and CCA is repeated over shifting time intervals.

The analysis indicates TWC as a strong ENSO precursor for at least one model, and the coupling between the modes shows signs of internal variability. Also, the ways in which the models reconstruct the TWC, in its intensity and shape, and its coupling with ENSO appear to be affected by the changes in resolution. These results provide an insight over the different degrees at which HigResMIP model experiments are able to characterize the features of a fundamental process like ENSO. Moreover, they cast a light over the impacts that a change in oceanic or atmospheric resolution can have when simulating a coupled mode.
Atmospheric and Soil Signals in a Climate Dependent Stalagmite Radiocarbon Record from Northern Turkey
Authors: Therre Steffen , Fohlmeister Jens , Fleitmann Dominik , Friedrich Ronny , Lausecker Marleen , Schröder-Ritzrau Andrea , Frank Norbert
Published: March 2020

The climatic controls of stalagmite radiocarbon (14C) remain one focus of modern paleoclimatology due to recent efforts and achievements in 14C calibration. The Hulu cave 14C record (Cheng et al., 2018) has proven the potential of stalagmites from temperate climate zones for atmospheric 14C reconstruction. However, a constant dead carbon fraction (DCF) in stalagmites over long periods is rather exceptional. In our study, a high-resolution 14C record (N=111) of a precisely U-Series dated stalagmite from Sofular Cave (Northern Turkey) with elemental Mg/Ca ratio data is presented. A phase of low and constant DCF (12.5% ± 1.6%, N=20) between 10 and 14 kyr BP, together with relatively stable Mg/Ca ratios suggest stable hydrological soil/karst conditions above the cave. However, we observe unstable soil conditions for the period before 14 kyr BP where DCF is strongly variable between a lower threshold of approximately 5% and an upper limit of 25%. Near a phase of slow growth at ~17 kyr BP DCF as high as 38% is observed on sub-centennial timescales.  The combination of stable isotopes, element ratios, radiocarbon and U-series data allows for multi-proxy analysis of the impact of rapid climate changes like D/O events on the incorporation of 14C into stalagmites. Between 15 and 27 kyr BP, hydrological changes have a large impact on limestone dissolution systematics which is reflected in fast DCF variations on sub-centennial timescales. A growth stop between 21 and 23 kyr BP is resolved. Although a comprehensive reconstruction of atmospheric 14C variations is not possible for the entire growth period, the stalagmite reproduces the deviation from the IntCal13 record (Reimer et al. 2013) seen in the Hulu 14C data at ~40 kyr BP during the Laschamp geomagnetic reversal and provides further inside on the climate dependency of 14C incorporation in stalagmites.

References

Cheng, H., Lawrence Edwards, R., Southon, J., et al.: Atmospheric 14C/12C changes during the last glacial period from Hulu cave, Science, 362(6420), 1293–1297, doi:10.1126/science.aau0747, 2018.

Reimer, P. J., Bard, E., Bayliss, A., et al.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP, Radiocarbon, 55(4), 1869–1887, doi:10.2458/azu_js_rc.55.16947, 2013.
Revamping the GFZ Energy Magnitude computation procedure to establish a new service
Authors: Strollo Angelo , Di Giacomo Domenico , Bindi Dino , Zaccarelli Riccardo
Published: March 2020

Location and magnitude are the primary information released by any seismological observatory to characterize an earthquake. Nowadays, the size of large enough earthquakes are routinely measured in terms of released seismic moment (moment magnitude, Mw). Whereas events with Mw above about 5.5 populate seismological archives connected to global monitoring networks, the moment magnitude of smaller events require the analysis of regional and local dense networks, or the establishment of empirical relationships to convert other magnitude scales into Mw (e.g., local magnitude to moment magnitude conversions). Since Mw is constructed over a physical parameter, it does not saturate. Moreover, being the seismic moment connected to tectonic features such as fault area and the average slip, Mw became the reference magnitude for seismic hazard studies. Although Mw accomplishes perfectly the task of characterizing the earthquake size, it does not provide the most complete view about the earthquake strength since Mw is insensitive to changes in the rupture dynamics. An assessment of the amount of the seismic energy released by an event (energy magnitude Me) is allowing to complement Mw with a measure of the earthquake size more suitable to evaluate the earthquake shaking potential.

Aiming at introducing soon a new real-time service providing Me for major earthquakes we are presenting in this study the results of benchmark tests against the procedure proposed by Di Giacomo et al., in 2008 [1] as well as the analysis performed on a larger data set including all major events available in the GEOFON catalogue with a published moment magnitude since 2011. The initial procedure has been translated to a python code within the Stream2segment package [2] and leveraging on EIDA and IRIS data services, more than 2000 station for ~5000 events since 2011 have been downloaded and processed. The large data set used and the real-time application pose new challenges, among them the teleseismic distance, the strongly unbalanced network and the real-time data flow making the data set used dynamic. We present and discuss here the effects of these complications and how we are tackling them towards the implementation of new service at GFZ computing Me in real-time.

 

[1] Di Giacomo, D., Grosser, H., Parolai, S., Bormann, P., and Wang, R. (2008), Rapid determination of Me for strong to great shallow earthquakes, Geophys. Res. Lett., 35, L10308, doi:10.1029/2008GL033505.

[2] Riccardo Zaccarelli, Dino Bindi, Angelo Strollo, Javier Quinteros, Fabrice Cotton; Stream2segment: An Open‐Source Tool for Downloading, Processing, and Visualizing Massive Event‐Based Seismic Waveform Datasets. Seismological Research Letters ; 90 (5): 2028–2038. doi: https://doi.org/10.1785/0220180314
Biomarker distributions in surface sediments of the northern Barents Sea: a basis for accurate palaeo sea-ice reconstructions
Authors: Pienkowski Anna J. , Husum Katrine , Belt Simon , Smik Lukas
Published: March 2020

An understanding of modern sea-ice proxy distributions relative to measured environmental parameters underpins accurate palaeo reconstructions necessary for correct future projections. We here present new data on highly-branched isoprenoid (HBI) lipid biomarkers produced by sea-ice diatoms (IP25, IPSO25) and phytoplankton (HBI III, HBI IV) in marine surface sediments taken in a south-north transect east of Svalbard as part of the Nansen Legacy project. Collectively, these biomarkers can be used to reconstruct seasonal spring sea-ice (SpSIC) and the seasonal sea-ice edge. Eight sites at ~78-83°N were sampled by multicorer. All cores contain abundant biomarkers, except the northernmost station. Biomarker-based SpSIC shows a general south-north increase, mimicking observational sea-ice concentration satellite-based means (1988-2017). The HBI T25 index suggests ice edge phytoplankton blooms at southern stations, agreeing with the general pattern of increased phytoplankton HBIs previously reported from the eastern Barents Sea. As a next step, these new biomarker findings will be used to reconstruct longer-term (Holocene) variability in sea-ice in this region. 
The influence of Antarctic topography on jet streams and Rossby waves in the Southern Hemisphere.
Authors: Patterson Matthew , Woollings Tim , Bracegirdle Tom
Published: March 2020

Eddy-driven jets are sustained through momentum transport by Rossby waves, which propagate along potential vorticity (PV) gradients. In the atmosphere, spatial variations in time-mean PV are mostly dominated by the variation of the Coriolis parameter with latitude. However, at high southern latitudes, a significant perturbation to the distribution and mixing of PV is provided by the Antarctic Plateau, which rises up to 4km above sea level. It is therefore possible that this orography affects Rossby wave propagation and hence affects the circulation in mid-latitudes.

We show through a set of semi-realistic and idealised experiments, that Antarctic topography plays a fundamental role in shaping the structure of the Southern Hemisphere extratropics. In particular, we perform runs with and without the Antarctic Plateau and demonstrate that the Plateau alters Rossby wave structure and propagation, thereby changing the momentum fluxes. Removal of the Plateau weakens the Indian Ocean jet and has a substantial effect on the flow downstream over the South Pacific. Here, the characteristic split jet pattern is destroyed and the flow at high latitudes stagnates. This also illustrates the prevalence of downstream development in the Southern Hemisphere and the strong connections between the flow over the South Pacific and Indian Oceans.   
Deep Slab folding and the deformation of the Persian domain
Authors: Boutoux Alexandre , Briaud Arthur , Faccenna Claudio , Ballato Paolo , Rossetti Federico , Funicello Francesca , Blanc Eric Jean-Philippe
Published: March 2020

To unravel the Neotethys subduction history and the evolution of the slab morphology at depth since the mid-Cretaceous, we produced a synthesis of the main events affecting the Persian domain. This synthesis is focused on the upper and lower plates (i.e. the Persian and the Neotethys ocean, respectively) of the subduction system and is based on the compilation of available structural, geochemical and geochronological data. Overall, this compilation allows exploring the structural evolution of the Persian domain and the Neotethys oceanic lithosphere on map view and along selected cross-sections.

Furthermore, we performed a 2D single-sided numerical model where we explored the slab behavior at depth and its influence on upper plate deformation. The model suggests that episodic deformation is driven by the folding slab behavior at the mantle transition zone. We combine our data and numerical model into a conceptual scenario to overcome the complexity of the kinematics of the Neotethys slab since the Early Cretaceous. Our modeling approach shows that back-arcs opening and associated extensional deformation are driven by the roll-back of the folded slab into the mantle transition zone. In contrast, back-arc closure and upper plate shortening are triggered by the roll-over of the folding slab. Finally, we associate the widespread, upper plate, Early Miocene marine flooding event to the Neotethys slab avalanche into the lower mantle.
Gross Primary Production and False Spring: a spatio-temporal analysis
Authors: Izquierdo-Verdiguier Emma , Zurita-Milla Raúl , Moreno-Martinez Álvaro , Camps-Valls Gustau , Klisch Anja , Atzberger Clement , Running Steven W.
Published: March 2020

Phenological information can be obtained from different sources of data. For instance, from remote sensing data or products and from models driven by weather variables. The former typically allows analyzing land surface phenology whereas the latter provide plant phenological information. Analyzing relationships between both sources of data allows us to understand the impact of climate change on vegetation over space and time. For example, the onset of spring is advanced or delayed by changes in the climate. These alterations affect plant productivity and animal migrations.

Spring onset monitoring is supported by the Extended Spring Index (SI-x), which are a suite of regression-based models for key indicator plant species. These models (Schwartz et al. in 2013) are based on daily maximum and minimum temperature from the first day of the year (January 1st). The primary products of these models are the timing of first leaf and first bloom, but they also provide derivative products such as the timing of last freeze day and the risk of frost damage day (damage index) for each year. This information helps to understand if vegetation could have suffered from environmental stressors such as droughts or a late frost events. The effects of environmental stressors in vegetation could be captured by the false spring index, which relates the first leaf day and the last freeze day. Moreover, this information could be used to understand plant productivity as well as to evaluate the economic impact of climate change.

Previous works studied the relationship between remote sensing and plant level products by means of spatial-temporal analysis between Gross Primary Production (GPP) and a spring onset index. However, they did not consider the possible impact of false spring effect in these relationships. Here, we present a spatial-temporal analysis between GPP and the damage index to better understand the effect of false springs (in annual gross photosynthesis data). The analysis is done for the period 2000 to 2015 over the contiguous US and at spatial resolution of 1 km. We used the MODIS annual sum of GPP and the damage and false spring indices derived from the SI-x models.
Estimation of Flow Velocity During Flash Floods with the synergy of Unmanned Aerial Systems (UAS) data and Ground Observations: The Case of 2017 Mandra Flash Flood, Greece
Authors: Spyrou Nafsika Ioanna , Stanota Eirini Spyridoula , Diakakis Michalis , Andreadakis Emmanuel , Lekkas Efthymios , Vassilakis Emmanuel
Published: March 2020

Unmanned Aircraft Systems (UAS) can be used to enhance monitoring of a wide range of environmental parameters, including acquiring data on various types of hydro-geomorphic phenomena.

Their capabilities to provide on demand images and videos of high resolution, are particularly useful in the case of flash flood phenomena, which occur in spatial and temporal scales that do not favor traditional monitoring processes.

In this work, flow velocity is estimated using aerial imaging acquired by means of an Unmanned Aircraft Vehicle (UAV) as well as ground observations during the catastrophic flash flood event of November 2017 in Mandra, Greece.

In these imaging detailed tracing of various floating objects and particles such as light trash, debris etc. was carried out using multiple high-resolution video frames with specific time marks. Water velocity estimations were also cross-examined using flood mark-derived velocity hydraulic heads extracted by ground observations after the flood.

The analysis was applied at a variety of locations across the study area, leading to a map of velocities for parts of the floodplain. Velocity values varied significantly depending on location, reaching up to 10m/s.

The UAS proved to be very useful for the collection of important information for an extended area during the flood since a large portion of it was inaccessible due to road closures and safety issues. Nevertheless, the approach comes with certain limitations, including flight regulations, safety precautions and that rainfall is at a level that allows the deployment of a UAV during a flash flood.

The findings show that the integration of aerial with ground observations in post-flood analysis contributes the completeness and accuracy of datasets regarding specific flash flood parameters and in the future could become a useful source of information, especially in data-poor regions.
Biochar combined with manure application can decrease organic matter decomposition compared to manure alone in the dry tropical cropland of south India
Authors: Seki Mayuko , Sugihara Soh , Miyazaki Hidetoshi , Jegadeesan Muniandi , Kannan Pandian , Tanaka Haruo
Published: March 2020

Soils in the dry tropical croplands of south India are inherently low in soil carbon (C) stock, and it is essential to accumulate the soil C for sustainable soil management. Biochar is generally considered to be a useful material that enhance the soil C stock, though its real effect on soil C dynamics is still unclear especially in the dry tropical croplands such as south India. Thus, our objective was to evaluate the effect of biochar application on soil C dynamics for optimal soil management in south India. Field experiment was conducted in Tamil Nadu state (Inceptisols) from Sep. 2017 to Apr. 2019 (1.5 years), which include two times sorghum cultivation (each 4 months) with six treatment plots (control (C), biochar (B) (8.2 Mg C ha-1), farmyard manure (FYM) (F) (1.1 Mg C ha-1), chemical fertilizer (CF) (100 kg N; 40 kg P ha-1), biochar and FYM (B+F), and biochar and chemical fertilizer (B+CF)). We applied biochar once at the beginning of the experiment to evaluate the effective duration of biochar in soil after application, while we applied FYM every year before crop cultivation. We periodically measured the CO2 efflux rate (29 times totally) with continuous environmental data including soil moisture (0-15 cm) and soil temperature (5 cm), and estimated the total CO2 flux as C output, based on the relationship between the CO2 efflux rate and environmental data. We found that the CO2 efflux rate in the B+F plot tended to be lower than the F plot throughout the experimental period, though the significant difference between the B+F plot and F plot was only in the cultivation period of the 1st year, in case of using the analysis of variance for each cultivation period separately. We found that cumulative CO2 flux in the B+F plot (2.2 Mg C ha-1 1.5 year-1) was also lower than the F plot (2.5 Mg C ha-1 1.5 year-1), and that biochar and FYM application decreased ca. 0.3 Mg C ha-1 1.5 year-1 decomposition compared to the application of FYM alone. This might be because combined application of biochar and FYM decreased the soil microbial activity, resulting in the lower FYM decomposition in the B+F plot. Our results indicate that biochar combined with FYM application would effective for soil C sequestration, and hence for sustainable soil management in the dry tropical cropland.
Extracting flash floods distribution and frequencies in arid regions using post flood spectral indices
Authors: Isaacson Sivan , Rottman Stanley R. , Storz-Peretz Yael
Published: March 2020

Deserts are characterized by high spatial and temporal variability of precipitation resulting in high spatio-temporal variation of floods occurrences. Adjacent drainage basins or even adjacent channels within a single basin may differ significantly and unpredictably in the number of floods per year. Moreover, common river planforms, such as alluvial fans and braided channels are often subjected to high rates of sediment transport and morphological changes, leading to a frequent shifting of the flow. These arise the need for high spatial and temporal resolution mapping of the dynamics of flash floods occurrence and distribution in the active channels. Because of the short duration (few hours to one day) of flash-floods that characterize arid ephemeral streams (wadis), a post- flood index must be applied.

 

Based on ground monitoring of floods during two hydrological seasons 2017-2018 and 2018-2019 in the Arava vally, Israel , we marked the dates of all flood events and downloaded pre and post satellite images sentinel-2 (A and B) and of Landsat-8) for each event. The combined temporal resolution of both satellites in this area varies from one to five days. We used spectral indices that were originally developed for mapping open water bodies (NDWI, MNDWI) or for monitoring vegetation vigor (NDVI, LSWI). In order to eliminate the varying lithology background effect, we used a normalized time difference equation.

The results show that all bands and indices are sensitive to the flow events. Using single bands change detection is subjected to noise, causing from changes in reflectance that are not due to flood impact. By using the LSWI and MNDWI, this noise considerably eliminates. The results indicated high signal of flood extent when using the MNDWI and LSWI indices even three days after the flood.

This type of monitoring is essential for infrastructure planning, drainage management and river rehabilitation as well as ecological interface. It is also the base for validating models predicting flash floods which save humane lives and properties.
The role of geophysics for urban environment characterization: the case study of Matera (southern Italy)
Authors: Calamita Giuseppe , Gallipoli Maria Rosaria , Perrone Angela , Serlenga Vincenzo , Stabile Tony Alfredo , Tragni Nicola , Panebianco Serena , Bellanova Jessica , Piscitelli Sabatino , Izzi Francesco , Amato Lorenzo , Lascaleia Giuseppe , Maio Donato , Salvia Vito
Published: March 2020

The global urbanization process, along with the environmental impacts it carries with it, requires the adoption of innovative programming strategies for the sustainable and efficient management of natural resources and to improve the resilience of cities to natural disasters. In this scenario where the acquisition of a deeper and as thorough as possible knowledge of the territory on the problems connected with the phenomena of hydrogeological instability and natural risk in general that can affect the inhabited centers pose new challenges both at the level of government and for the scientific community. Further, it is also important to organize and make these complex information easily accessible to stakeholders, i.e. administrators, planners and civil protection.

In the framework of two national projects, CLARA (CLoud plAtform and smart underground imaging for natural Risk Assessment) and SPOT (Development of a Platform for the provision of innovative services based on Earth Observation data), a systemic approach based on the integration of the latest enabling technologies (remote sensing and ground-based, active and passive, direct and indirect, multi-sources and multi-resolution) for the geo-physical characterization (seismic and electromagnetic) of the surface and near-surface and for the dynamic characterization of soil structure/infrastructure interactions was applied in the urban area of the city of Matera (southern Italy). By adopting the open-government and open-data paradigms, all the information collected have been eventually organized and shared in a web-gis along with geospatial data already available on different and independent web-services of local government authorities (region and municipality).
A thermal dissociation CAPS for detection of NOy species within the MetNO2 project
Authors: Kuß Annika , Kubistin Dagmar , Holla Robert , Plaß-Dülmer Christian , Tensing Erasmus , Utschneider Felix , Prosteder Maximilian , Worton David R. , Persijn Stefan , Iturrate-Garcia Maitane , Wegener Robert
Published: March 2020

As a toxic and reactive gas, nitrogen dioxide (NO2) influences air quality and health, the self-cleaning power of the atmosphere and photochemical smog formation. Reliable scientific data with high quality and comparability are required for national and international decision-makers. The quality of the NO2 measurements is crucially dependent on the quality of the calibration standards. In order to achieve the quality goals required, the MetNO2 project within the EMPIR (European Metrology Program for Innovation and Research) program aims to provide accurate and stable NO2 calibration standards for operational use at air quality stations.

To characterise the impurities of the newly developed standards a Thermal Dissociation - Cavity Attenuated Phase Shift (TD - CAPS) system has been set up, based on the design from Sadanaga et al. (2016). The device includes four heated channels for the differentiation of NO2, peroxy and alkyl nitrates and HNO3. In parallel, a gold converter coupled with a chemiluminescence detector was deployed for detection of the total sum of NOy. First results of the performance of the TD-CAPS used for impurity analysis of NO2 standards will be presented.

 

Reference: Sadanaga et al. Review of Scientific Instruments 87.7 (2016), 074102
On the accuracy of gravity fields obtained with Newton integrals on a hollow sphere
Authors: Jeanniot Ludovic , Thieulot Cedric , Root Bart , Naliboff John , Spakman Wim
Published: March 2020

The mass-density distribution of the Earth drives mantle convection and plate tectonics but is poorly known. We aim to predict gravity fields as a constraint for geodynamical modelling. In order to compute synthetic Earth gravity one must define a spherical geometry filled with a density model. Density models for the whole mantle down to the CMB come from tomographic models which therefore require converting speed waves velocities to density using a scaling factor.

We use a discretised integration method to compute globally gravity acceleration, gravity anomalies, potential and gradients, in the state of the art finite element code ASPECT.

Three density models are tested separately: a density field obtained from SL2013 and S40RTS tomographic models for the deep mantle, and the density model CRUST1.0 for the thin upper lithosphere layer. We combine these 3 datasets into one to create a composite model which is compared to the global seismic model LLNL-G3D-JPS of Simmons et al. (2015). We test the sensitivity of gravity prediction on the use of various conversion scaling factors of shear wave velocity to density. We find that the scaling factor profile also has a major impact on gravity prediction.

Finally, we present early results of the gravity field prediction for two local areas, the Indian-Tibet plate boundary and the Mediterranean Sea. Gravity predictions are compared to satellite gravity.
Can old growth alpine forests be biophysical barriers against current heat waves?
Authors: Montagnani Leonardo , Obojes Nikolaus , Wolf Gert , Garcia Santos Glenda
Published: March 2020

Can old growth alpine forests be biophysical barriers against current heat waves?

The current climate crisis requires an urgent understanding of ecosystem features dampening and alleviating the increasing radiation forcing. To this end, emission of latent heat from forests emerges with its relevance among the terrestrial ecosystem properties. It is not clear, however, if the different forest structures and ages act similarly, depending on the species composition, or if their structure has a role.

We performed a research on the hydrological cycle in the highly instrumented research facility in Renon forest, Italian Alps, belonging to the ICOS European infrastructure. The site is covered by a dense but structurally heterogeneous spruce forest, characterized by a young sector, with 30 years trees and an old forest sector composed by 200 years old trees.

Energy and water balance are quantified by eddy covariance instrumentation, 12 sap flux sensors in trees representative of the forest tree ages and 20 below-canopy pluviometers in each of the two forest structures. With these pluviometers, we quantified the relative role of canopy interception as a function of LAI density, precipitation intensity and duration. Water discharge and fog interception measurements allowed the closure of the water cycle at catchment scale.

Interestingly, we found that the water cycle is largely decoupled from the ground. In the old forest section, the fraction of water reaching the ground in the old sector is the 0.42±0.17 (vs. 0.67±0.17 in the young sector) of incoming precipitation. This suggests that in old alpine forests the hydrological cycle takes place largely in the crown and the old forest is using a large fraction of precipitation to dissipate heat.

Our results support the view of stand age as emerging property in the atmosphere-biosphere interaction and highlight the relevance of old forests in dampening the recurrent heat spells spreading across Europe, with the Alps and their remaining old growth forests standing as biophysical barriers.
Predicting erosion hazards in river catchments
Authors: Cooper James , Li Xiaorong , Plater Andy
Published: March 2020

Climate change is projected to cause considerable pressure on our environment and communities. In particular, an increase in flooding and extreme erosion events is foreseeable as a result of anticipated increase in the frequency and severity of storms (Gorman et al., 2009). In the absence of timely and strategic intervention, climate change is taking us closer to more uncertain (non-linear, stochastic) and potentially more catastrophic climatic impacts. This research aims to 1) based on the combined application of the ‘Reach’ and ‘Catchment’ modes of Caesar-Lisflood, quantify the uncertainty in the risk posed by flooding and erosion hazards for current climate conditions and for two future epochs (2021-2040 & 2061-2080) using the UKCP18 projections; 2) to assess the economic impact of erosion hazards on critical infrastructure such as buildings, transport networks (roads and bridges), agricultural land, etc; and 3) evaluate the vulnerability and resilience of these assets to differing storm regimes. The above-mentioned storm-related hazards and economic impacts are integrated in a web-based geospatial decision-support tool for visualization which ultimately supports sustainable and resilient decision making for a changing climate.
Using the results of dangerous cryogenic processes investigations in student education
Authors: Grebenets Valery , Tolmanov Vasily , Fedin Vladimir , Sinitskiy Anton
Published: March 2020

The department traditionally holds specialized practices of cryolithology and glaciology. Recently, specialized field course (sometimes international) have been concentrated in the Arctic region of Russia in the south of Yamal. The studies were focused on the investigation of the permafrost features in the regions, on assessing the permafrost dynamics and processes, affected by the various number of factors.

Here, the results of studies dedicated to the assessment of dangerous cryogenic processes impact on the infrastructure of the far north are widely introduced. Unique studies of the level of deformation of the infrastructure of the northern settlements are carried out during the establishment and development of an unfavorable geocryological situation.  Monitoring observations are carried out both in natural and in urbanized conditions,  allow us to compare the intensity of the processes, evaluate the contribution of technogenesis and climatic changes.

Based on the research results, students and researchers receive the necessary data and field results for analyzing the dynamics and changes in geotechnical systems in the context of an increase in the technogenic press and temperature increase in the region.

Investigation is supported by the RFBR project 18-05-60080 “Dangerous nival-glacial and cryogenic processes and their influence on infrastructure in the Arctic”

 
The SO/PHI instrument on Solar Orbiter and its data products
Authors: Solanki Sami K. , Hirzberger Johann , Wiegelmann Thomas , Gandorfer Achim , Woch Joachim , del Toro Iniesta José Carlos
Published: March 2020

A central instrument of Solar Orbiter is the Polarimetric and Helioseismic Imager, SO/PHI. It is a vector magnetograph that also provides data for helioseismology. SO/PHI is composed of two telescopes, a full-disk telescope (FDT) and a high-resolution telescope (HRT). The HRT will observe at a resolution as high as 200 km on the solar surface, while the FDT will obtain the magnetic field and velocity of the full solar disc whenever it observes. SO/PHI will be the first solar spectro-polarimeter to leave the Sun-Earth line, opening up some unique perspectives, such as the first detailed view of the solar poles. This will allow not just a more precise and exact mapping of the polar magnetic field than possible so far, but will also enable us to follow the dynamics of individual magnetic features at high latitudes and to determine solar surface and sub-surface flows right up to the poles. In addition to its standard data products (vector magnetograms, continuum images and maps of the line-of-sight velocity), SO/PHI will also provide higher-level data products. These will include synoptic charts, local magnetic field extrapolations starting from HRT data and global magnetic field extrapolations (from FDT data) with potential field source-surface (PFSS) models and possibly also non-potential models such as NLFFF (non-linear force-free fields), magnetostatics and MHD. The SO/PHI data products will usefully complement the data taken by other instruments on Solar Orbiter and on Solar Probe, as well as instruments on the ground or in Earth orbit. Combining with observations by Earth-based and near-Earth telescopes will enable new types of investigations, such as stereoscopic polarimetry and stereoscopic helioseismology.
Evolutionary full-waveform inversion with dynamic mini-batches
Authors: van Herwaarden Dirk-Philip , Boehm Christian , Afanasiev Michael , Thrastarson Solvi , Krischer Lion , Trampert Jeannot , Fichtner Andreas
Published: March 2020

We present an evolutionary full-waveform inversion based on dynamic mini-batch optimization, which naturally exploits redundancies in observed data from different sources and allows the model to evolve along with the amount of available information in the data.

Quasi-random subsets (mini-batches) of sources are used to approximate the misfit and the gradient of the complete dataset. The size of the mini-batch is dynamically controlled by the desired quality of the approximation of the full gradient. Within each mini-batch, redundancy is minimized by selecting sources with the largest angular differences between their respective gradients, and spatial coverage is maximized by selecting candidate events with Mitchell’s best-candidate algorithm. Information from sources included in a previous mini-batch is incorporated into each gradient calculation through a quasi-Newton approximation of the Hessian, and a consistent misfit measure is achieved through the inclusion of a control group of sources.

By design, the dynamic mini-batch approach has several main advantages: (1) The use of mini-batches with adaptive sizes minimizes the number of redundant simulations per iteration, thus potentially leading to significant computational savings. (2) Curvature information is accumulated and used during the inversion, using a stochastic quasi-Newton method. (3) Data from new events or different time windows can seamlessly be incorporated during the iterations, thereby enabling an evolutionary mode of full-waveform inversion.

To illustrate our method, we start an inversion for upper mantle structure beneath the African plate. Starting from a smooth 1-D background model for a dataset recorded in the years 1990 to 1995, we then sequentially add more and more recent data into the inversion and show how the model can evolve as a function of data coverage. The mini-batch sampling approach allows us to incorporate data from several hundred earthquakes without increasing the computational burden, thereby going significantly beyond previous regional-scale full-waveform inversions.
Late glacial and Holocene glacier fluctuations at the Sub-Antarctic Island Kerguelen in the Southern Indian Ocean
Authors: Bakke Jostein , Arnaud Fabien , Deline Philip , Guiguet-Covex Charline , Linge Henriette , Ravanel Ludovic , Støren Eivind , van der Bilt Willem
Published: March 2020

The Southern Hemisphere`s westerly winds play a critical role in regulating Earth`s climate by shielding Antarctica from low-latitude heat, driving global ocean circulation and regulate the uptake of CO2 in the Southern Ocean. Both strength and position of this globally significant atmospheric pattern are rapidly shifting in the face of ongoing global warming. A string of recent studies links these developments to dramatic coupled changes in temperature, precipitation, sea-ice coverage and glacier extent that unfold across the Southern Ocean region. Critically, a lack of baseline information restricts our ability to understand the causes and patterns of these shifts and represent them robustly in the future projections that underpin climate policies. To help do so, we utilize the sensitivity of glaciers to atmospheric climate change and the potential of glacier-fed lake sediments to record this signal through time. For this purpose, we integrate emerging sedimentological, geochemical and glacier modelling tools in a new method framework to reconstruct changes in glacier extent, temperature and precipitation on human-relevant timescales. To do so, we rely on a number of novel sedimentological and geochemical approaches. These include biomarker-based temperature reconstructions, exposure dating of moraines and the use emerging non-destructive scanning techniques (e.g. Computed Tomography – CT) to fingerprint depositional pathways. Our study area in this cross-disciplinary project is the poorly investigated sub-Antarctic Kerguelen Archipelago, well-situated in the core southern westerly wind belt. During an extensive 2019 field campaign, we collected 130 meters of sediment cores from six lakes, 110 rock samples for exposure dating and numerous catchment samples. 
The various facets of digital repeat photography fully exploited with the phenopix R package
Authors: Filippa Gianluca , Cremonese Edoardo , Galvagno Marta , Migliavacca Mirco
Published: March 2020

Flux towers are more and more often equipped with digital cameras (aka phenocams) widely used to track canopy greenness. Phenocam-derived vegetation indices can capture land surface phenology but also seasonality in gross primary production (GPP) estimated from eddy covariance (EC) measurements. In addition, phenocams can be used to track seasonal development of different species or individuals within the same image scene, and evaluate spatial variability within the footprint of EC measurements. Further, phenocams were recently used to quantify disturbance such as late frost, fires, storms etc. in forested ecosystems and the impact of climate extremes on ecosystem functioning. With the recent rapid development of phenocameras, the need for up-to-date, efficient, open-source software is also increasing tremendously. The phenopix R package was developed for this purpose. In this contribution, we will provide an overview of the software capabilities, with a special focus on how EC measurements can benefit from phenocam data streams.

The steps of a basic processing workflow will be illustrated, including drawing a region of interest (ROI) on an image; extracting red, green and blue digital numbers from a seasonal series of images; depicting greenness index trajectories; fitting a curve to the seasonal trajectories; extracting relevant phenological thresholds (phenophases); characterizing phenophase uncertainties. A focus will be made on recent software developments, including the calculation of camera-derived NDVI and other infrared-based indices, and the handling of shifts in the field of view of the phenocameras.
New constraints on Plio-Pleistocene East Antarctic Ice Sheet thickness: cosmogenic exposure data from western Dronning Maud Land
Authors: Andersen Jane L. , Newall Jennifer C. , Blomdin Robin , Sams Sarah E. , Fabel Derek G. , Koester Alexandria J. , Stuart Finlay M. , Lifton Nathaniel A. , Fredin Ola , Caffee Marc W. , Glasser Neil F. , Rogozhina Irina , Suganuma Yusuke , Harbor Jonathan M. , Stroeven Arjen P.
Published: March 2020

Reconstructing past ice surface changes is key to test and improve ice-sheet models. Yet, data constraining the past behaviour of the East Antarctic Ice Sheet are sparse, limiting our understanding of its response to past and future climate changes. Here, we attempt to test whether the ice-sheet margin in western Dronning Maud Land has thinned since the last glacial maximum or whether it perhaps thickened in places due to increased precipitation associated with warmer climates. We report cosmogenic multi-nuclide (10Be, 26Al, 36Cl, 21Ne) data from bedrock and erratics on nunataks along Jutulstraumen ice stream and the Penck Trough in western Dronning Maud Land, East Antarctica. Spanning elevations between 751-2387 m above sea level, and between 5 and 450 m above the contemporaneous local ice sheet surface, the samples record apparent exposure ages between 2 ka and 5 Ma. The highest bedrock sample indicates (near-) continuous exposure since at least the Pliocene, with a very low apparent erosion rate of 15±3 cm Ma-1. However, there are also clear indications of a thicker-than-present ice sheet within the last glacial cycle, thinning ~35-120 m at several nunataks during the Holocene (~2-11 ka). Owing to difficulties in retrieving suitable sample material from the often rugged and quartz-poor mountain summits, and due to the presence of inherited nuclides in many of our samples, we are unable to present robust thinning estimates from elevational profiles. Nevertheless, the results clearly indicate ice-surface fluctuations of several hundred meters within the last glacial cycle in this sector of the EAIS, between the current grounding line and the edge of the polar plateau. Finally, inverse modelling of the cosmogenic multi-nuclide inventories in bedrock yields estimates of total erosion and ice cover across multiple glacial cycles. Our results show that the EAIS in western Dronning Maud Land was thicker than present during most of the Quaternary, covering sample sites up to 200 m above the present-day ice sheet for ~80 % of this period. Thinning of the ice since the last glacial maximum, combined with a long-term record of thicker-than-present ice, indicate that the ice sheet below the polar plateau in western Dronning Maud Land generally expands and thickens during climate cooling, despite decreasing precipitation associated with a cooler Southern Ocean.
Subdaily instrumental data from Graz, Austria, starting in 1795
Authors: Foelsche Ulrich , Kraml Erik , Besser Bruno
Published: March 2020

The meteorological station at University of Graz, Austria has been recently recognised as WMO "Centennial Station", with measurements taken at
the same location going back to the year 1891. Combined with data from nearby downtown stations (in particular at the former location of the University) the record extends back to the year 1836 - in this form the data are currently used in the HISTALP dataset. This record can, however, be extended at least four decades back in time:

Mr. Rospini, a man of great interest in natural sciences (and later his son and grandsons) measured  temperature and pressure three times per day (morning, noon and evening) in the historic center of Graz - close to the former location of the University. Measurements apparently started as early as 1781, and have been continuously published in the "Grätzer Zeitung" from 1795 onwards. So far, we have been able to compile an almost uninterrupted
record since 1797 (with just a few weeks missing in total), and we are trying to fill the remaining gaps for the two previous years. Temperatures are given in Réaumur, recorded at 7, 15 and 22 (confirmed for 1823, very likely for the time before). For the year 1837 we performed a consistency check, comparing our recently retrieved data with those from the University (which are used in the HISTALP dataset), yielding an annual mean offset of just +0.2 °C.

With those subdaily measurements, we cannot only extend the climate record, but we can also attempt to analyse particularly interesting years. Using the temperature recorded at 15:00 as proxy for the maximum temperature, we could identify the extremely warm Summer of 1834, with at least 35 days, where the temperature maximum was 30 °C or higher. Since we slightly underestimate the true number of “Hot Days” with this approach, we can assume that this summer was not too different from the record Summer of 2003, where our meteorological station recorded 41 “Hot Days” (with actual maximum temperature measurements). The second highest value in the “official” time series was obtained in 2015 with 34 “Hot Days”. The year 1816, on the other hand, was indeed a "year without summer" - also in Graz, with just 11 days reaching a temperature of 25 °C or more.
Effective forcing in CMIP5 assuming nonconstant feedback parameter and linear response
Authors: Fredriksen Hege-Beate
Published: March 2020

We investigate a new algorithm for estimating time-evolving global forcing in climate models. The method is an extension of a previous method by Forster et al. (2013), but here we also allow for a globally nonlinear feedback. We assume the nonlinearity of this global feedback can be explained as a time-scale dependence, associated with linear temperature responses to the forcing on different time scales, as in Proistosescu and Huybers (2017). With this method we obtain stronger forcing estimates than previously believed for the representative concentration pathway experiments in CMIP5 models. The reason for the higher future forcing is that the global feedback has a higher magnitude at the smaller time scales than at the longer time scales – this is closely related to provided arguments for the equilibrium climate sensitivity showing changes with time.

We find also that the linear temperature response to our new forcing predicts the modelled response quite well, although the response is a little overestimated for some CMIP5 models. Finally, we discuss the assumptions made in our study, and consistency of our assumptions with other leading hypotheses for why the global feedback is nonlinear.

 

References:

Forster, P. M., T. Andrews, P. Good, J. M. Gregory, L. S. Jackson, and M. Zelinka (2013), Evaluating adjusted forcing and model spread for historical and future scenarios in the cmip5 generation of climate models, Journal of Geophysical Research, 118, 1139–1150, doi:10.1002/jgrd.50174.

Proistosescu, C., and P. J. Huybers (2017), Slow climate mode reconciles historical and model-based estimates of climate sensitivity, Sci. Adv., 3, e1602, 821, doi:10.1126/sciadv.1602821