bluuebunny/crossref_metadata_2025 huggingface dataset:
Downscaling and bias correction of seasonal forecasts to support climate services for the Alpine regions
Authors: Crespi Alice , Callegari Mattia , Greifeneder Felix , Notarnicola Claudia , Petitta Marcello , Zebisch Marc
Published: March 2020

The interest in trustable and accurate information about climate and its variability at local scale is currently increasing not only within the scientific community, but also by local stakeholders, political administrators and private companies. Clear, operative and close to the users’ needs climate information represent relevant support tools for a wide range of decision-making policies, including vulnerability assessment, risk management and energy production.

Seasonal forecasts, in particular, allow to provide predictions of the climate up to several months ahead and therefore they could represent precious sources of information for a wide range of activities, such as for the optimization of renewable energy sector. However, specific approaches are needed to deal with the probabilistic nature of seasonal forecasts and post-processing methods are required to adapt their large spatial resolution to the local scales of specific applications. This is particularly true for orographically complex areas, such as the Alpine regions, where coarse-resolution data could lead to remarkable under or overestimations in the predicted variables.

In this framework, we present a downscaled and bias-corrected version of seasonal forecasts provided by the ECMWF’s seasonal forecasting system (SEAS5) for temperature, precipitation and wind speed over the Alpine area and spanning the period 1983 – 2018. The approach is based on the bilinear interpolation of the 1°x1° original fields onto the target 0.25°x0.25° resolution and on the quantile-mapping procedure using ERA-5 reanalysis data for the calibration. The ERA-5 reanalysis dataset is chosen as reference in order to allow the application of the implemented scheme over different areas. The accuracy and skills of the post-processed seasonal forecast fields are evaluated, also in comparison with observations and the performance of alternative downscaling schemes.

The presented study supports the activities of the H2020 European project SECLI-FIRM on the improvement of the seasonal forecast applicability for energy production, management and assessment.
Saharan dust events in the Carpathian Basin (Central Europe) in 2018: provenance analyses by granulometry, XRD and SEM methods
Authors: Kovács János , Gammoudi Nadia , Kovács Alex , Varga György
Published: March 2020

Sediment samples were collected from Morocco, Algeria and Tunisia (as possible source sediments) and from Hungary (2018 dust events), and analyzed with the following measurements: laser diffraction, X-ray powder diffraction, automated static image analysis, and scanning electron microscopy (SEM). Similarities were expected in the results of desert-originated samples and samples collected in Hungary. In order to identify the typical dust transportation routes and possible source areas, the backward trajectories were plotted using the NOAA HYSPLIT model [1].

According to particle size distribution results, active dust emission is taking place at the location of investigated desert samples, and the samples collected in Hungary can be the particles out-blown from the source areas. The evaluated mineralogical results show that every sample contains quartz and phyllosilicates. SEM micrographs and image analyses results assume that the samples collected in Hungary are from the same source area. Using HYSPLIT application, trajectories of two analyzed dust events reveal that one desert sample, as a possible source is excluded and that the two trajectories cross each other at a junction point above North Africa (depression area between the Hoggar Mts. and Tademaït). This point can be the sought possible source location. The results in this study are convenient with those founded by Blott et al. [2] and Ahmed et al. [3]

Acknowledgment

Support of the National Research, Development and Innovation Office NKFIH KH130337 and K120213 is gratefully acknowledged.

References

Draxler, RR, Rolph, GD. 2012. HYSPLIT (HYbrid Single‐Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website. NOAA Air Resources Laboratory: Silver Spring, MD. http://ready.arl.noaa.gov/HYSPLIT.php, last accessed 2019/03/20.

Blott, S. J., Al-Dousari, A. M., Pye, K., Saye, S. E.: Three-dimensional characterization of sand grain shape and surface texture using a nitrogen gas adsorption technique. Journal of Sedimentary Research 74, 156–159‏ (2004).

Ahmed, M., Al-Dousari, N., Al-Dousari, A.: The role of dominant perennial native plant species in controlling the mobile sand encroachment and fallen dust problem in Kuwait. Arabian Journal of Geosciences 9, 134 (2016)
Modeling the interplay between droughts, floods and human activities
Authors: Mazzoleni Maurizio , Odongo Vincent , Mondino Elena , Di Baldassarre Giuliano
Published: March 2020

Several studies showed an increasingly negative impact of droughts and floods due to the combined effects of socio-economic and climatic factors. To better understand changes in hydrological risk over time, it is fundamental to unravel the complex interactions between increasing urbanization, population growth, water management strategies and increasing frequency and intensity of hydrological hazards. To this end, various socio-hydrological models have been developed over the past decade to explain the dynamics of risk generated by either human-flood or human-drought interactions. This study proposes a new analytical framework to represent, for the first time, the deeply intertwined interactions between humans and both hydrological extremes, i.e. floods and droughts. A new system dynamic model is developed and then applied to explore the phenomena generated by human-water interactions in relation to different water management strategies. The results show the ability of the proposed model to capture multiple socio-hydrological phenomena that have been empirically observed (levee effect, supply-demand cycle, reservoir, rebound, and sequence effects). In particular, our model is capable to capture dynamics that did not emerge in previous socio-hydrological models where human, drought and flood interplay is considered independently. Given its explanatory value, the model can contribute to a better interpretation of changes in drought and flood risk associated with anthropogenic influences.
On the suitability of two-layer energy-balance models for representing deep ocean heat uptake
Authors: Shatwell Peter , Czaja Arnaud , Ferreira David
Published: March 2020

Over 90% of the excess heat energy due to global warming is taken up by the oceans. Because of this, ocean heat uptake and planetary heat uptake can be considered equivalent. This heat energy is readily taken up by the oceanic mixed-layer on decadal timescales and subsequently transferred to the thermocline and deep ocean below on longer, centennial timescales by different ventilation mechanisms. The ventilation rate is affected by many things including the mixed-layer depth, the strength of the overturning, and mode-water formation. In current two-layer energy-balance models (EBMs), all ventilation mechanisms are reduced and parameterised by a simple linear vertical heat-exchange term that depends on the temperature difference between the upper and lower layers (representing the mixed-layer and deep ocean, respectively). 

Two-layer EBMs have been used successfully to reproduce the global mean surface temperature responses for CMIP5 models in abrupt CO2-quadrupling experiments. Little attention has been paid to the EBM-predicted deep ocean response, however. We perform an abrupt CO2-doubling experiment using an idealised aquaplanet model with a simple geometry that splits the ocean into small, large, and southern ocean basins. By fitting a two-layer EBM regionally to each basin's deep temperature response, we find that it provides a good fit only for the small basin. We suggest this is due to the small basin exhibiting a deep overturning circulation — not seen in the other model basins — which connects the ocean surface to its interior; only this ventilation mechanism can be successfully parameterised by a linear vertical heat-exchange. By considering the wind-driven circulation theory of Rhines and Young, we suggest a new parameterisation for the two-layer EBM deep ocean heat uptake that may be more suitable for basins without deep overturning.
The IGFS gravity field observations and products contributions to GGOS infrastructure
Authors: Vergos Georgios S. , Barzaghi Riccardo , Bovalot Sylvaint , Ince Elmas Sinem , Jäggi Adrian , Reguzzoni Mirko , Wziontek Hartmut , Kelly Kevin
Published: March 2020

Through its structure the International Gravity Field Service (IGFS) promotes the interaction, cooperation and synergy between the Gravity Services, namely the Bureau Gravimétrique International (BGI), the International Service for the Geoid (ISG), the International Geodynamics and Earth Tides Service (IGETS), the International Center for Global Earth Models (ICGEM), the International Combination Service for Time-variable Gravity Fields (COST-G) and the International Digital Elevation Model Service (IDEMS).

Furthermore, via its Central Bureau hosted at the Aristotle University of Thessaloniki (Greece), IGFS provides a link to the Global Geodetic Observing System (GGOS) Bureaus in order to communicate their requirements and recommendations to the IGFS-Centers. Moreover, IGFS provides a coordination host for the utilization of gravity-field related products and services towards their inclusion within a GGOS consistent frame meeting the necessary precision and accuracy requirements.

In this work, an outline is given on the recent activities of IGFS, namely those related to the contributions to the implementation of: the International Height Reference System/Frame; the Global Geodetic Reference System/Frame; the new Global Absolute Gravity Reference System/Frame and rhe combination of temporal monthly global gravity field models. Particularly, the impact that these activities have and will have in improving the estimation of the Earth’s gravity field, either at global and local scale, is highlighted also in the framework of GGOS.
Diurnal cycle of GNSS-derived precipitable water vapour in tropical regions
Authors: Bałdysz Zofia , Nykiel Grzegorz , Baranowski Dariusz , Latos Beata , Figurski Mariusz
Published: March 2020

Convective processes in the tropical atmosphere and their diurnal cycles have important repercussions for the circulations in the tropical regions and beyond. Monitoring of the water vapour content in the tropical atmosphere remains a challenge due to its high temporal and spatial variability. Global models tend to fail to correctly capture the diurnal convection, limiting forecasting accuracy. In this work, we investigated precipitable water vapour (PWV) diurnal cycle, precipitation and infrared  brightness temperature (TB) data over the tropical area. We used in-situ observations from 44 IGS (International GNSS Service) stations covering time span of 18 years, together with satellite-based precipitation and cloudiness data, taken from the Tropical Rainfall Measurement Mission gridded dataset (TRMM 3B42 v7) and the global, merged infrared (IR) dataset, respectively. The data provided an opportunity to examine the characteristics of a diurnal cycle of PWV, precipitation and TB over the study area in greater detail than before.

In particular, our results show that the diurnal cycle of PWV and TB were almost entirely dominated by mono-modal distributions. The diurnal cycle of precipitation onshore (continental areas or big islands; continental regime) had a single late afternoon peak, and that offshore (small islands; oceanic regime) had both a midday and a nocturnal peak. Daily amplitude phase shift of PWV and precipitation at onshore stations with a continental regime consistently occurred at the same time, while TB maximum peaked about five hours later. Furthermore, results show that the daily mean and the amplitude of the diurnal cycle of PWV, precipitation and TB appeared smaller on offshore stations, exhibited to an oceanic regime, than on onshore, continental stations. Additional analysis of seasonal variations of GNSS-derived PWV shows the usefulness of such measurements for tracking propagation of longer-scale phenomena, such as Inter Tropical Convergence Zone (ITCZ), Southeast Asian monsoon or East Asian summer monsoon.
Flooding risks change due to land use and precipitation change in Northern Taiwan
Authors: Chao Yi-Chiung , Liu Pei-Ling , Chen Chun-Che , Li Hsin-Chi , Hsu Chih-Tsung , Chen Yung-Ming
Published: March 2020

According to the records, an average of 5.3 typhoons hit Taiwan each year over last decade. Typhoon Morakot in 2009 was considered the most severe typhoon, which caused huge damage in Taiwan, including 677 casualty and roughly NT$ 110 billion ($3.3 billion USD) in economic loss. More and more researches documented that typhoon intensity will increase with climate change in western North Pacific region. It will induce the more severe natural disasters, such as flooding, landslide, and water resources risks in Taiwan in the future. Most research focused on the disaster impact assessment in climate change and was assumed that the land use are unchanged in the future. On the other hand, land use changes is another key reason for increasing the hazard risks. Therefore, this study tries to build a land use change model to simulate the land use spatial distribution, and discuss whether the extreme precipitation or the land use change is the major factor to increase flooding risks in Taoyuan City, northern Taiwan in the future.

This study applied that Markov chain to project the land use demand in 2036 and used the binary logits regression to establish the land use change probability model to allocate the land use spatial distribution in the future. Then, there are two different precipitation intensities used and integrated the allocated land use to evaluate the risks of flooding in 2036.

We successfully established land use spatial allocation model, and linked the allocated results to disaster impact assessment. Assessment results showed that land use change slightly increases the flooding risks; but extreme precipitation induces more severe flooding risks than land use change. Our results point out that extreme precipitation will induce the more severe flooding risks than land use. In addition, the restricted land development policy could efficiently reduce the flooding risks. If government implement climate change adaptation activities with land use management policies at the same time would possibly reduce the climate change disaster impact in the future.
The poleward shift of the Subtropics in the Northern Hemisphere winter: time of emergence of the climate change signals
Authors: D'Agostino Roberta , Scambiati Ascanio Luigi , Jungclaus Johann , Lionello Piero
Published: March 2020

Here we consider the areas located below the descending branch of the Hadley cell and characterized by arid or semiarid climate in the northern hemisphere. There are controversial suggestions that they are shifting northwards and this trend will continue during the 21st century.  We investigate the time-of-emergence (ToE) of corresponding climate change signals using  the Max Planck Institute Grand Ensemble (MPI-GE), a model experiment which allows by design to disentangle the role of external forcing from the internal climate variability on climate signals. Here we show that the ToE and the regions where it will occur are strongly dependent on the variable that is adopted for the analysis. For most  variables, ToE of regional subtropical expansion would occur only after the end of the 21st century and only in few irregularly distributed areas. Therefore, in spite of the consensus among projections on the future boreal subtropical broadening, the strong role played by the internal climate variability prevents to consider the observed trends in reanalyses over last decades a robust signal of anthropogenic forcing.
Spatially distributed mass balance of 14 Icelandic glaciers, 1945−2017. Trends and link with climate.
Authors: Belart Joaquín M. C. , Magnússon Eyjólfur , Berthier Etienne , Gunnlaugsson Águst Þ. , Pálsson Finnur , Aðalgeirsdóttir Guðfinna , Jóhannesson Tómas , Björnsson Helgi
Published: March 2020

Excluding the three largest ice caps, Icelandic glaciers have, until recently, received limited attention in terms of mass balance observations over the last century. In this study, mass balance estimates from 1945 to 2017 are presented, in decadal time spans, for 14 glaciers (total area 1054 km2) subject to different climatic forcing in Iceland. The mass balances are derived from airborne and spaceborne stereo imagery and airborne lidar, and correlated with precipitation and air temperature by a first order equation including a reference-surface correction term. This permits statistical modelling of annual mass balances and to temporally homogenize the mass balances for a region-wide, multidecadal mass balance study. The mean (standard deviation) mass balances of the target glaciers were −0.43 (0.17) m w.e. a−1 in 1945−1960, 0.01 (0.21) m w.e. a−1 in 1960−1980, 0.10 (0.23) m w.e. a−1 in 1980−1994, −0.98 (0.44) m w.e. a−1 in 1994−2004, −1.23 (0.57) m w.e. a−1 in 2004−2010 and 0.06 (0.35) m w.e. a−1 in 2010−2017. The majority of mass loss occured in 1994−2010, accounting for 22.5±1.6 Gt (1.4±0.1 Gt a−1). High decadal mass-balance variability is found on glaciers located at the south and west coasts,
in contrast to the glaciers located inland, north and northwest. These patterns are likely explained by the proximity to warm (south and west) versus cold (northwest) oceanic currents.
Forecasting sub-resolution temporal variability of irradiance
Authors: Kreuwel Frank , van Heerwaarden Chiel
Published: March 2020

Variability of solar irradiance is an important factor concerning large-scale integration of solar photovoltaics (PV) systems onto the electricity grid. Calculations of irradiance are computationally expensive, leaving operational meso-scale forecasting models struggling to achieve accurate results. Moreover, such models deliver outputs at a temporal resolution in the order of hours, whereas from a grid-integration point of view, minute-to-minute variability is a major concern. In previous work, we found that absolute power peaks in the order of seconds are up to 18% higher compared to 15-minute resolution for irradiance and even upwards of 22% higher for household PV systems. Moreover, these maximum peaks in output power are solely observed under mixed-cloud conditions, for which alse the greatest variability is found. In this work we present a machine-learning model which can forecast sub-resolution variability of irradiance, based on standard meso-scale outputs of the HARMONIE model of the The Royal Netherlands Meteorological Institute (KNMI). For training and validation, irradiance measurements obtained at a 1-second interval are used of the Baseline Surface Radiation Network (BSRN) site of Cabauw. A tree-based model was employed, for which the optimum members were constructed using extreme gradient boosting. In this work, we explore the dominant features of the model and link the machine-learned-relations to meteorological processes and dynamics. This research was executed in collaboration with the Distribution Grid Operator Alliander.
Strategies for the monitoring of rapid changes in paraglacial systems
Authors: Felbauer Lucia , Mergili Martin , Fischer Andrea
Published: March 2020

Glaciers are retreating at an historically unprecedented pace. Climate-determined processes are changing markedly. As a result, proglacial areas are expanding. Paraglacial dynamics are expected to further increase in significance, controlling sediment supply and landscape change in mid- to high latitudes for the next few hundred years. Paraglacial adjustment in proglacial areas has not been fully explored to date and there is an urgent need to monitor and understand these systems in more detail.

We present first insights into a planned project called glacier2go aiming to investigate changes in the paraglacial system in the highly variable and sensitive areas determined by rapid glacier retreat at two Austrian glaciers. The project aims at the development of a new holistic monitoring system, where remote sensing and field work data are combined and integrated to achieve a deeper understanding of the different stages of evolution of the paraglacial system, and to detect changes through classification approaches. The project glacier2go will fill a research gap by developing an automatic land cover classification model with very high spatial and temporal resolution for monitoring geomorphic changes. glacier2go will capture surface changes through contrasting geomorphic-classification maps.

The proposed survey will be conducted on selected glacier forefields in the Austrian Alps with Jamtalferner (Tyrol, Silvretta) and Pasterze (Carinthia, Glockner range) as the main study sites. glacier2go will be executed as a dissertation project hosted at the Interdisciplinary Institute of Mountain Research (IGF) in Innsbruck, Austria. International cooperation partners in the field of geomorphology, photogrammetry and geoinformation are on board to realize this project.

At the current stage first data comparisons are shown, emphasising the needed research on the interlinkage of geomorphology and the methodical development of new monitoring systems. Setting these first insights into the framework of paraglacial geomorphology leads to the emergence of new research questions. The associated challenges and first approaches for their solution are presented at the conference.
Can we improve gravity wave parameterizations by imposing sources at all altitudes in the atmosphere?
Authors: Ribstein Bruno , Millet Christophe , Lott Francois , de la Camara Alvaro
Published: March 2020

A multiwave non-orographic gravity wave (GW) scheme is adapted to represent waves of small intrinsic phase speed and sources located at all altitudes in the troposphere and middle atmosphere. Using reanalysis data, these changes impose larger amplitude saturated waves everywhere in the middle atmosphere, which permits to produce more realistic GW vertical spectra than when the phase speeds are large and the sources are in the troposphere only. The same scheme, tested online in the Laboratoire de Météorologie Dynamique Zoom(LMDz) general circulation model, performs at least as well as the operational non-orographic GW scheme.  Some modest benefits are seen, for instance, in the equatorial tilt with altitude of the winter jets in the middle atmosphere. Although the scheme includes the effects of inertial waves, which are more and more often detected in the mesosphere, the configuration that gives a reasonable climatology in LMDz hinders the vertical propagation of these parameterized waves and do not generally reach mesospheric altitudes.
Impacts of wildfire aerosols on global energy budget and climate: The role of climate feedbacks
Authors: Jiang Yiquan , Yang Xiu-Qun , Liu Xiaohong
Published: March 2020

Aerosols emitted from wildfires could significantly affect global climate through perturbing global radiation balance. In this study, Community Earth System Model with prescribed daily fire aerosol emissions is used to investigate fire aerosols’ impacts on global climate with emphasizing the role of climate feedbacks. The total global fire aerosol radiative effect (RE) is estimated to be -0.78±0.29 W m-2, which is mostly from shortwave RE due to aerosol-cloud interactions (REaci, -0.70±0.20 W m-2). The associated global-annual mean surface air temperature (SAT) change (∆T) is -0.64±0.16K with the largest reduction in the Arctic regions where the shortwave REaci is strong. Associated with the cooling, the Arctic sea ice is increased, which acts to re-amplify the Arctic cooling through a positive ice-albedo feedback. The fast response (irrelevant to ∆T) tends to decrease surface latent heat flux into atmosphere in the tropics to balance strong atmospheric fire black carbon absorption, which reduces the precipitation in the tropical land regions (southern Africa and South America). The climate feedback processes (associated with ∆T) lead to a significant surface latent heat flux reduction over global ocean areas, which could explain most (~80%) of the global precipitation reduction. The precipitation significantly decreases in deep tropical regions (5°N), but increases in Southern Hemisphere tropical ocean, which is associated with the southward shift of the Inter-Tropical Convergence Zone and the weakening of Southern Hemisphere Hadley cell. Such changes could partly compensate the interhemispheric temperature asymmetry induced by boreal-forest fire aerosol indirect effect, through intensifying the cross-equator atmospheric heat transport.
Estimation of distributed parameters at regional scale by history-matching of a multi-layered sedimentary aquifer
Authors: Aissat Ryma , Pryet Alexandre , Saltel Marc , Dupuy Alain
Published: March 2020

Large scale, physically-based groundwater models have been used for many years for water resources management and decision-support. Improving the accuracy and reliability of these models is a constant objective. The characterization of model parameters, in particular hydraulic properties, which are spatially heterogeneous is a challenge. Parameter estimation algorithms can now manage numerous model runs in parallel, but the operation remains, in practice, largely constrained by the computational burden. A large-scale model of the sedimentary, multilayered aquifer system of North Aquitania (MONA), in South-West France, developed by the French Geological Survey (BRGM) is used here to illustrate the case. We focus on the estimation of distributed parameters and investigate the optimum parameterization given the level of spatial heterogeneity we aim to characterize, available observations, model run time, and computational resources. Hydraulic properties are estimated with pilot points. Interpolation is conducted by kriging, the variogram range and pilot point density are set given modeling purposes and a series of constraints. The popular gradient-based parameter estimation methods such as the Gauss–Marquard–Levenberg algorithm (GLMA) are conditioned by the integrity of the Jacobian matrix. We investigate the trade-off between strict convergence criteria, which insure a better integrity of derivatives, and loose convergence criteria, which reduce computation time. The results obtained with the classical method (GLMA) are compared with the results of an emerging method, the Iterative Ensemble Smoother (IES). Some guidelines are eventually provided for parameter estimation of large-scale multi-layered groundwater models.
Denudation history of the French Massif Central: new insights from thermochronology, basement-basin cross-sections and semi-automated planation surfaces mapping
Authors: François Thomas , Baby Guillaume , Bessin Paul , Baptiste Julien , Barbarand Jocelyn , Guillocheau François , Lasseur Éric , Briais Justine , Robin Cécile
Published: March 2020

Documenting surface uplift of basement areas is challenging, usually due to large gaps in the sedimentary record. In order to address this issue for the French Massif Central, we here investigate its denudation history through an integrated study that involves planation surface mapping, Apatite Fission-Track (AFT) Analysis and basement to basin cross-sections.

First, Planation surfaces were identified using a semi-automated fuzzy classification of pixels based on relationships between DEM derivatives (slope, curvature, ruggedness and incision) and field-recognized training samples.  Then, their different generations and age ranges were discriminated from hypsometry, fault partitioning and relationships with dated sedimentary and/or volcanic remnants, providing constraints on basement exhumation. Afterwards, integrating the previous planation surface analysis, geological cross-sections were produced from the Massif Central basement to the surrounding basins (Aquitaine Basin and Paris Basin). These sections provide local thicknesses estimates of the missing sedimentary cover over basement domains. Theses local thicknesses and exhumation phases were finally used as constraints to produce a thermal history modelling and a denudation map of different areas of the French Massif Central estimated from AFT inversion.

Our results show different burial and exhumation patterns with i) a main burial of its western parts (Limousin, Rouergue) during Jurassic times followed by an important regional denudation (1 to 2 km of missing cover and crystallized basement) during the early Cretaceous and ii) an Upper Cretaceous burial of its northeastern parts (Morvan, Forez) followed by an uppermost Cretaceous to Paleogene exhumation (<1 km of missing cover and crystallized basement). This further illustrates the different behavior of each units of the Massif Central during the Mesozoic to Cenozoic times. These results will ultimately be discussed and placed back into the western European deformation framework.

 

(This work is founded and carried out in the framework of the BRGM-TOTAL project Source-to-Sink)
Cryoegg: development and field trials of a wireless subglacial probe for deep, fast-moving ice
Authors: Prior-Jones Michael , Bagshaw Elizabeth , Lees Jonathan , Clare Lindsay , Burrow Stephen , Wadham Jemma , Werder Mauro A , Karlsson Nanna B , Dahl-Jensen Dorthe , Christoffersen Poul , Hubbard Bryn
Published: March 2020

Innovative technological solutions are required to access and observe subglacial hydrological systems beneath glaciers and ice sheets. Wireless sensing systems can be used to collect and return data without the risk of losing data from cable breakage, which is a major obstacle when studying fast flowing glaciers and other high-strain environments. However, the performance of wireless sensors in deep and fast-moving ice has yet to be evaluated formally. We report experimental results from Cryoegg: a spherical probe that can be deployed along an ice borehole and either remain fixed in place or potentially travel through the subglacial hydrological system. The probe makes measurements in-situ and sends them back to the surface via a wireless link. Cryoegg uses very high frequency (VHF) radio to transmit data through up to 1.3 km of cold ice to a surface receiving array. It measures temperature, pressure and electrical conductivity, returning all data in real time. This transmission uses Wireless M-Bus on 169 MHz; we present a simple “radio link budget” model for its performance in cold ice and confirm its validity experimentally. Power is supplied by an internal battery with sufficient capacity for two measurements per day for up to a year, although higher reporting rates are available at the expense of battery life. Field trials were conducted in 2019 at two locations in Greenland (the EastGRIP borehole and the RESPONDER project site on Sermeq Kujalleq/Store Glacier) and on the Rhone Glacier in Switzerland.  Our results from the field demonstrate Cryoegg’s utility in studying englacial channels and moulins, including estimating moulin discharge through salt dilution gauging with the instrument deployed deep within the moulin. Future iterations of the radio system will allow Cryoegg to transmit through up to 2.5 km of ice.
Incorporating hydraulic traits within the functional strategy spectrum of woody plants globally
Authors: Liu Daijun , Esquivel-Muelbert Adriane , Sadler Jonathan , Acil Nezha , Papastefanou Phillip , Rammig Anja , A. M. Pugh Thomas
Published: March 2020

Global-change-type droughts, resulting from climate warming and changes in precipitation patterns are believed to be accelerating the rates of tree mortality globally. Simulation of these changes, for instance in global vegetation models, requires parameterisation of plant strategies with respect to drought. However, our understanding of realised combinations of drought-relevant physiological and morphological traits across the range of global forest types is still limited.

We constructed a dataset consisting of 12 functional traits related to resource acquisition, growth rate, plant defence, water conductivity and hydraulic vulnerability for 11,000 woody species globally. We used a novel envelope-based analysis to assess the functional space occupied by these species whilst circumventing the problem of sparse sampling for many traits. We then subdivided the space into a continuum of strategic “clusters”. These clusters only map partially onto groupings of traditional plant functional types based on leaf type and phenology.

We found that the functional spaces for the plant strategies are highly interrelated globally, showing that the traits related to resource acquisition are positively associated with growth rates and leaf water conductivity, which together are negatively associated with conservative traits of plant defence, although these associations differ greatly between needleleaf and broadleaf species. However, the trait related to hydraulic failure demonstrated positive associations with resource acquisition, but no relationship with woody defence. Furthermore, there are clear linkages between water flow and hydraulic vulnerability traits, and climatic drivers relating to aridity and plant distribution.

The clusters identified in this systemic work can form a basis for new plant functional type definitions, facilitating including plant hydraulics in global vegetation models and, taking a step towards making reliable large-scale simulations of drought-driven tree mortality.
Detailed Calibration of the Off-Axis Optical Characteristics for the X-Ray Telescope onboard Hinode
Authors: Shin Junho , Sakurai Takashi , Kano Ryouhei , Moon Yong-Jae , Kim Yeon-Han
Published: March 2020

The X-Ray Telescope (XRT) onboard the Hinode satellite has a specially designed Wolter type grazing-incidence (GI) optics with a paraboloid-hyperboloid mirror assembly to measure the solar coronal plasma of temperatures up to 10 MK with a resolution of about one arcsec. One of the main purposes of this scientific mission is to investigate the detailed mechanism of energy transfer processes from the photosphere to the upper coronal region leading to its heating and the solar wind acceleration. To theoretically model the three-dimensional coronal structures is sensitive to the values of plasma properties at the base of solar corona and thus requires beforehand accurate empirical description of those properties. Though the telescope has provided unprecedented observations of solar corona for more than a decade, due to a wide field of view of 34 x 34 arcmin covering the full Sun, the optical performance of the instrument gradually deteriorates as it goes away from the optical center. For this reason, the off-axis characteristics of Hinode/XRT should be examined with care in order to precisely interpret the coronal plasma properties near the solar limb area.

This presentation will explain the importance of accurate calibration of the optical characteristics, especially for the data taken in the off-axis region. Our previous study has shown that the scattered light caused by the XRT mirror surface roughness has a power-law distribution and also shows an energy dependence, with which the PSF profile from the core to the scattering wing has been completed. We will introduce in this study how the level of scattering wing can be determined quantitatively for each focal plane filter from in-flight data analysis. We have also evaluated the vignetting effect in Hinode/XRT by analyzing the 2D distribution of effective area in the field of view taken from MSFC/XRCF pre-launch experiment. It is revealed that, unlike the case of Yohkoh/SXT, the degree of offset of an optical center is not serious and thus shows little deviation from rotational symmetry. Also important is that the vignetting pattern in XRT shows an energy dependence, which has never been considered before for the analyses of XRT data. More interesting results on the calibration of Hinode/XRT scattered light and the correction of vignetting effect will be introduced and discussed thoroughly. 
Medical geographic modeling of spatiotemporal changes of naturally determined diseases under the changing climate and economic development of the Russian Arctic
Authors: Malkhazova Svetlana , Orlov Dmitry , Bashmakova Irina
Published: March 2020

This research aims at the solution of environmental problems related to sustainable and economically efficient development of the North, which could enhance the quality of life and health of the population in the changing Russian Arctic. The medical geographic modeling of spatiotemporal patterns of naturally determined diseases is based on the detailed database covering the Arctic zone of Russia. The role of factors affecting the spread of diseases is unequal, with the climatic factor regarded as the most significant at all levels of territorial differentiation. At the highest (national) level, this factor determines the latitudinal zoning, which, in turn, determines the existence conditions of disease hosts and vectors and, ultimately, the foci of diseases. At regional level, the effect of climate is traced in monthly mean temperatures, temperature extremes, precipitation, snow depth, length of no-frost period, etc. Changes of these characteristics influence the poikilothermic (cold-blooded) arthropods, as well as the pathogens spending a part of their life cycles in the arthropods’ organisms. Another important factor is related to water resources, particularly, water-table height and ecological state of water bodies. Comparative analysis of hydrological and hydrochemical data, and their total impact on morbidity rates in terms of pathogenicity eco-indices, can serve as an additional tool for detecting the critical infection areas and population early warning. The original methodology is applied to evaluate the actual medical environmental situation, to forecast possible spatiotemporal changes in morbidity, including due to the most virulent infections, and to elaborate recommendations to public health authorities on planning the preventive and health-improving activities in the Arctic.
Signature of coseismic off-fault damage in intermediate- and far-field radiation
Authors: Okubo Kurama , S. Bhat Harsha , Rougier Esteban , A. Denolle Marine
Published: March 2020

Off-fault damage is observed around fault cores in a wide range of length scales, which is identified as an aggregation of localized fractures via geological and geodetic observations, or as low-velocity zone via seismological tomography. However, its seismological observables in earthquake traces, e.g. change in source spectra and/or radiation pattern, remains to be investigated. 

Okubo et al. (2019) proposed an approach framework of physics-based dynamic earthquake rupture modeling with coseismic off-fault damage using the combined finite-discrete element method (FDEM). It shows a non-negligible contribution of coseismic damage to rupture dynamics, high-frequency radiation and overall energy budget, whereas the model domain is limited in the near-field region. This study efficiently computes intermediate- and far-field radiation propagating from earthquake sources with coseismic off-fault damage, and to identify its signature in the seismic traces.

We first conduct the dynamic earthquake rupture with coseismic damage and compute synthetic near-field radiation using FDEM-based software tool, HOSSedu, developed by Los Alamos National Laboratory. We then couple the output of HOSSedu to SPECFEM2D in order to compute intermediate- and far-field radiation. The HOSS-SPECFEM2D coupling can resolve complexities over wide range of length scales associated with earthquake sources with coseismic damage and wave propagation.

We conduct 2D dynamic earthquake rupture modeling with a finite planar fault as canonical simplest model. The comparison between the cases with and without allowing for coseismic off-fault damage shows differences in intermediate- and far-field radiation. 1) High-frequency components in ground motion are enhanced all around the fault. 2) The rupture arresting phase, which clearly appears at the stations located orthogonal to the fault for the case without off-fault damage, is damped due to the smoothed rupture arrest by coseismic damage around fault edges. 3) Radiated energy is enhanced in the direction parallel to the fault due to the substantial damage around fault edges.

These fundamental observables will help identify the existence of coseismic off-fault damage in real earthquakes. It would also contribute to resolve the mechanisms of earthquake sources and the potential distribution of aftershock locations. We also attempt to replace the planar fault to the real fault geometry, e.g. the fault system associated with the 2019 Ridgecrest earthquake sequence, and will investigate the signature of off-fault damage in the seismic traces recorded in intermediate- and far-field range.
On the fine structures in interplanetary radio emissions
Authors: Jebaraj Immanuel Christopher , Magdalenic Jasmina , Poedts Stefaan
Published: March 2020

Solar radio emission is studied for many decades and a large number of studies have been dedicated to metric radio emission originating from the low corona. It is generally accepted that solar radio emission  observed at wavelengths below the metric range is produced by the coherent plasma emission mechanism. Fine structures seem to be an intrinsic part of solar radio emission and they are very important for understanding plasma processes in the solar medium. Extensive reporting and number of studies of the metric range fine structures were performed, but studies of fine structures in the interplanetary domain are quite rare. New and advanced ground-based radio imaging spectroscopic techniques (e.g. LOFAR, MWA, etc.,) and space-based observations (Wind/WAVES, STEREO/WAVES A & B, PSP, and SolO in the future) provide a unique opportunity to study radio fine structures observed  all the way from metric to kilometric range.

Radio signatures of solar eruptive events, such as flares and CMEs, observed in the interplanetary space are mostly confined to type II (radio signatures of magneto-hydrodynamic shock waves), and type III  bursts(electron beams propagating along open and quasi-open magnetic field lines). In this study, we have identified, and analyzed three types of fine structures present within the interplanetary radio bursts. Namely, the striae-like fine structures within type III bursts, continuum-like emission patches, and very slow drifting narrowband structures within type II radio bursts. Since space-based radio observations are limited to dynamic spectra, we use the novel radio triangulation technique employing direction finding measurements from stereoscopic spacecraft (Wind/WAVES, STEREO/WAVES A & B) to obtain the 3D position of the radio emission. The novelty of the technique is that it is not dependent on a density model and in turn can probe the plasma density in the triangulated radio source positions (Magdalenic et al. 2014). Results of the study show that locating the radio source helps not only to understand the generation mechanism of the fine structures but also the ambient plasma conditions such as e.g. electron density. We found that fine structures are associated with complex CME/shock wave structures which interact with the ambient magnetic field structures. We also discuss the possible relationship between the fine structures, the broadband emission they are part of, and the solar eruptive events they are associated with.
Influence of spatial coherence of temperature anomalies on the supposed breakdown of the warmer spring – larger carbon uptake mechanism in northern high latitudes
Authors: Joyce Peter , Gloor Manuel , Brienen Roel , Buermann Wolfgang
Published: March 2020

Land vegetation growth in the northern high latitudes (north of 50˚N) is strongly temperature limited, thus anomalously warm years are expected to result in an increased drawdown of Carbon Dioxide (CO2) and vice versa. Piao et al (2017) concluded in an analysis of climate and CO2 data from Point Barrow, Alaska that there was a weakening response of northern high latitude spring carbon uptake to temperature anomalies over the last 40 years. They proposed that this is due to a weakening control of temperature on productivity. We have analysed northern high latitude climate and remote sensing vegetation indices, as well as atmospheric CO2 data at Point Barrow, with atmospheric transport analyses of the footprint seen at Barrow. Our results show no large-scale significant change in the spring NDVI-temperature relationship inside the footprint of Barrow, and across the high northern latitudes as a whole. This casts doubt on the assertion that the changing relationship between CO2 uptake and temperature is driven by a change in vegetation response to temperature. We thus tested several alternative mechanisms that could explain the apparent weakening, including a change in interannual variability of atmospheric transport (i.e. the footprint seen by Barrow) and the spatial agreement of temperature anomalies. We find that the heterogeneity of temperature anomalies increased over time, whereas there is no significant change in interannual variation in the footprint seen by Barrow. These results offer an additional explanation for the apparent decrease in spring temperature sensitivity of northern high latitude CO2 uptake.
Unraveling the retreat of the Aneto Glacier (Pyrenees, Spain) since the Little Ice Age
Authors: Campos Néstor , Alcalá Jesús , Watson C. Scott , Grima Nelson , Kougkoulos Ioannis , Quesada Adolfo
Published: March 2020

The Aneto is the largest glacier of the Pyrenees, is located on the Maladeta Massif (Central Pyrenees), close to the highest point of the range, the Aneto peak (42° 37' 52 N, 0° 39' 24 E; 3,404 m a.s.l.). This glacier is 675 meters long, occupy an area of 48.64 ha and their maximum altitude is 3,269 meters. The glacier front ends at 3,029 m a.s.l. and its mean slope is 23.6°, reaching a maximum of 56° in some parts. The main aim of this research is to present a detailed volumetric reconstruction of the glacier since the LIA and analyze their retreat. Based on morphological features, the extent of the glacier has been reconstructed for different periods (LIA, 1957, 2000, 2006, 2015 and 2017) and their ice volume, maximum ice thickness and ELAs has been calculated. To delimitate the glacier extension during the LIA, the moraines have been mapped by using photo interpretation techniques. For the recent phases digital aerial photographs and satellite images have been used. To estimate the topography of the glacier we used a simple steady-state model that assumes a perfectly plastic ice rheology, reconstructing the theoretical ice profiles and obtaining the extent of the glaciers. Later, to reconstruct the ice surface we calculated longitudinal profiles, with these reconstructed profiles a digital elevation model was created and combined with the bedrock topography in order to obtain the ice thickness at each phase. This bedrock topography was obtained by combining the glacier topography with a 3D model of the glacier obtained with geo-radar (ERHIN program, Government of Aragon).

This study reveals a great retreat of the Aneto Glacier since the LIA. The length of the glacier has been reduced from 1,970 m during the LIA to 675 m in 2017, and its tongue has retreated from 2,385 to 3,029 m a.s.l. during the same period. Regarding the area, it has been reduced from 245 ha during the LIA to 48.64 ha in 2017. During this period, the ELA has increased from 2,925 to 3,140 m a.s.l. The glacier volume has been reduced from 82.57 x106 m3 to 3.48 x106 m3, and the maximum ice thickness from 95 m to 27m. These data reveals a huge retreat of the glacier since the LIA, furthermore, this retreat has been more accelerated since the 50's.

 

Research funded by PYRENEEND project (10.18258/11352)