bluuebunny/crossref_metadata_2025 huggingface dataset:
Building synergies in regional climate services for Southeast Asia: The ASEAN Regional Climate Data, Analysis and Projections (ARCDAP) workshop series.
Authors: Lim Gerald , Moise Aurel , Rahmat Raizan , Timbal Bertrand
Published: March 2020

Southeast Asia (SEA) is a rapidly developing and densely populated region that is home to over 600 million people. This, together with the region’s high sensitivity, exposure and low adaptive capacities, makes it particularly vulnerable to climate change and extremes such as floods, droughts and tropical cyclones. While the last decade saw some countries in SEA develop their own climate change projections, studies were largely uncoordinated and most countries still lack the capability to independently produce robust future climate information. Following a proposal from the World Meteorological Organisation (WMO) Regional Association (RA) V working group on climate services, the ASEAN Regional Climate Data, Analysis and Projections (ARCDAP) workshop series was conceived in 2017 to bridge these gaps in regional synergies. The ARCDAP series has been organised annually since 2018 by the ASEAN Specialised Meteorological Centre (hosted by Meteorological Service Singapore) with support from WMO through the Canada-funded Climate Risk and Early Warning Systems (Canada-CREWS) initiative.

This presentation will cover the activities and outcomes from the first two workshops, as well as the third which will be held in February 2020. The ARCDAP series has so far brought together representatives from ASEAN National Meteorological and Hydrological Services (NMHSs), climate scientists and end-users from policy-making and a variety of vulnerability and impact assessment (VIA) sectors, to discuss and identify best practices regarding the delivery of climate change information, data usage and management, advancing the science etc. Notable outputs include two comprehensive workshop reports and a significant regional contribution to the HadEX3 global land in-situ-based dataset of temperature and precipitation extremes, motivated by work done with the ClimPACT2 software.

The upcoming third workshop will endeavour to encourage the uptake of the latest ensemble of climate simulations from the Coupled Model Intercomparison Project (CMIP6) using CMIP-endorsed tools such as ESMValTool. This will address the need for ASEAN climate change practitioners to upgrade their knowledge of the latest global climate model database. It is anticipated that with continued support from WMO, the series will continue with the Fourth workshop targeting the assessment of downscaling experiments in 2021.
Educational seismology in Nepali schools: tailored solutions to start a program
Authors: Subedi Shiba , Hetényi György , Denton Paul , Sauron Anne
Published: March 2020

Nepal is located above the convergent India-Eurasia plate boundary and has repeatedly experienced devastating earthquakes. During the 2015 magnitude 7.8 Gorkha earthquake, an often-reported experience was that people were not aware of the threatening seismic hazard and have insufficient level of preparedness. An important source of the problem is that earthquake-related topics are not part of the school curriculum. Earthquake education reaching a broad group of the population early in their lives is therefore strongly needed.

We have established an initiative in Nepal to introduce seismology in schools, which relies on two pillars: a low-cost seismic network with stations installed in schools (presented in another session) and educational activities in schools on earthquakes and the related hazards. For classical teaching, we have prepared educational materials adapted to the Nepali school system, labels and language. By using these materials, not only students in the schools but also local people in the community can learn earthquake education and follow guidelines for better preparedness. We also developed educational sessions using Raspberry Shake low-cost seismometers, for example to record earthquake waveforms and to allow learning-by-doing classroom activities.

For efficient implementation, we have organized a 2-day workshop for the school teachers to prepare them for the new teaching, which was presented by experts in the field and included lots of discussion to find the adapted level. Moreover, during our field visits, we give special lectures and also perform earthquake drills with the students. Well-prepared educational materials such as flyers and stickers are distributed to students, and demonstration tools for physics to schools. All the material from our project is freely available on our program’s website: http://seismoschoolnp.org.

We have started the program by choosing 22 schools in the region, and establishing direct contact with the teachers, principals and the local communities. We found this was an efficient way to implement the project, especially in rural areas. The preliminary and personal feedbacks reflect that this program is well received. A survey-based evaluation on the program’s impact on the local community is being carried out, and we plan to present results at the conference. We hope that the project is able to help this region to prepare for future earthquakes, and we seek that the initiative is spread to other regions  to make earthquake-safer communities across Nepal.
Spatial pedocomplexity in old-growth temperate forest driven by tree-uprooting: its formation and role in forest dynamics
Authors: Román-Sánchez Andrea , Samonil Pavel
Published: March 2020

Soil formation is a complex process that depends on topography, biota, bedrock, climate, and time. Despite of the great effort dedicated to explore soil evolution, little is known about the role of stochastic phenomena such as soil disturbance in spatial pedocomplexity formation in old-growth temperate forests. Within this study we aim to (i) reveal spatial pattern of chemical soil properties, (ii) explain differences in spatial pedocomplexity formation in A and B soil horizons.

The issue was studied in Zofinsky Primeval Forest Reserve (hereinafter Zofin) in SW Czech Republic. The Zofin has been strictly protected since 1838 and it represented the 4th oldest forest reserve in Europe. Zofin belongs to the global network of forest research plots ForestGeo (www.forestgeo.si.edu/) as the first site in continental Europe. We sampled 309 soil profiles on an area of 74 ha. In total 34 chemical soil properties were analysed in A and B horizons, particularly those, which affect soil evolution and tree growth. We analysed concentrations of Al, Fe, Mn, Ca, Na, Sr, Si fractions, characteristics of sorption complex (CEC, EA, base content), pH etc. 

We used descriptive statistics and geostatistics to spatial pedocomplexity study. The experimental variograms were modelled to fit them to the best theoretical distribution. From the theoretical distribution we calculated the spatial properties in each soil elements as the range, sill and nugget. Then, using AIC estimator, we selected the same best model for both horizons to compare the spatial parameters through parametric or not parametric statistical test depending on the normalization of the data.

The results indicate, for the first time, significantly longer ranges of spatial autocorrelation of soil properties in A horizon with comparison to B horizon, which is not common in geostatistical studies. It is most likely associated with rejuvenation of soil after tree uprooting. Neoformation of A horizon after soil disturbance proceeds quite rapidly and therefore some formerly disturbed A horizons are matured above immature B horizons. The range in both horizons for all chemical soil properties is independent (p-value <0.05), indicating that the driving factors for disturbance in horizon A and B are different. However, for rather biogenic soil properties as Mg, Ca, Na, EA, K there is dependence for horizon A and B (p-value>0.05), indicating similar effect of these elements in both horizons.
Multi-temporal analysis of post-fire vegetation spectral recovery over European forests
Authors: Spatola Maria Floriana , Rita Angelo , Borghetti Marco , Ripullone Francesco , Ferrara Agostino , Nolè Angelo
Published: March 2020

The disturbance and recovery of European Forest ecosystems are greatly affected by wildfires, requiring continued monitoring to observe vegetational structure altered over time. One of the most important parameters is “fire severity” defined as magnitude of environmental change caused by wildfires. Due to correlation between severity and post-fire recovery vegetation, fire severity is an  important indicator to define operations in the burned areas. Satellite based-data is becoming a key information for near real-time mapping and monitoring burned area after wildfire disturbances. Moderate resolution Imaging Spectroradiometer (MODIS) time-series data allows for both the capture of the initial disturbance and the ability to monitor the subsequent vegetation regeneration with spectral vegetation indices. In this study, the Google Earth Engine (GEE) platform, was used to analyse post-fire spectral recovery of European forests through the Normalized Difference Vegetation Index (NDVI) and the Relative Recovery Indicator (RRI) based on the Normalized Burn Ratio (NBR). We assessed Normalized Burn Ratio time series in order to determine trends in the short term rates of spectral recovery for three forest land cover classes and European Biogeographic regions disturbed by wildfire (2004-2013), using a series of 5-year post-disturbance time window. NBR pattern of mixed forests showed a lower variability than broadleaved and coniferous forest, indicating high resilience to environmental disturbances. Results indicate different trends of forest recovery according to different spectral indices analysed for European forest ecosystems. During the analysis period (2004-2013) we found that post-fire spectral recovery rates decreased over ten years of observation in each land cover classes and Biogeographic regions. These trends could be related to on-going climate changes affecting the Mediterranean region.

Keywords: Fire severity, Forest, Google Earth Engine, Modis (time series), Recovery, Spectral index, Wildfire.

 
Quantization of large earthquakes driven by asperities strain concentration patterns
Authors: Avlonitis Markos , Kotinas Dimitrios , Papadimitriou Eleftheria
Published: March 2020

The role of asperities in fault evolution has been received continuously increasing attention as critical areas where nucleation and cascade like failure may take place. They consist patches where the contact takes place across the fault rough surfaces, accumulating elastic strain during the interseismic period. More than one asperity rupture result to strong and large earthquakes, a phenomenon mostly characterizing large subduction earthquakes. Identification of the factors controlling single or multiple asperities failure and their spatiotemporal behaviour is a key issue in seismic hazard assessment. It is the aim of the present work to explore the role of different spatial patters of asperities as well as their different strength characteristics by means of simulation experiments via cellular automata models.  Initial results show that the earthquake distribution clearly depends on a) the total real contact area of asperities, b) the relative distance between asperity patches and c) the fraction of strain that asperities may sustain in comparison to the corresponding value of the non–asperity sites. Τhere is a definite range of the aforementioned controling parameters, which result to a non–typical earthquake magnitude distribution and where a clear departure from the classical power law–like Gutenberg – Richter relation is depicted. More specifically, for one (more than one well separated) asperity (–ies) with significant fraction of strain unlocking thresholds a non–typical earthquake size distribution emerges where for low magnitude earthquakes a power law still holds, but for higher earthquake sizes, a quantum like behaviour emerges, i.e. there is one (more than one) certain earthquake sizes that are more probable to occur. This manifests a characteristic earthquake model, which although not adequately supported by observational data, is present in several applications of simulator models.

 

Keywords:
asperities, large earthquake quantification, characteristic model, cellular automata

Acknowledgements
«Telemachus – Innovative Seismic Risk Management Operational System of the Ionian Islands» which is part of the Operational Program «Ionian Islands 2014-2020» and is co-financed by the European Regional Development Fund (ERDF) (National Strategic Reference Framework - NSRF 2014-20).
First continuous high-resolution aerosol record from the East Greenland Ice Core Project (EGRIP), covering the last 15,000 years
Authors: Jensen Camilla Marie , Erhardt Tobias , Sinnl Giulia , Fischer Hubertus
Published: March 2020

Ice sheets are reliable archives of atmospheric impurities such as aerosols and gasses of both natural and anthropogenic origin. Impurity records from Greenland ice cores reveal much information about previous atmospheric conditions and long-range transport in the Northern hemisphere going back more than a hundred thousand years.

Here we present the data from the upper 1,411 m from the EGRIP ice core, measuring conductivity, dust, sodium, calcium, ammonium, and nitrate. These records contain information about ocean sources, transport of terrestrial dust, soil and vegetation emissions as well as biomass burning, volcanic eruptions, etc., covering approximately the past 15,000 years. This newly obtained data set is unique as it provides the first high-resolution information about several thousands of years of the mid-Holocene period in Greenland that none of the previous impurity records from the other deep Greenland ice cores had managed to cover before due to brittle ice. This will contribute to further understanding of the atmospheric conditions for the pre-industrial period.

The ammonium record contains peaks significantly higher than the background level. These peaks are caused by biomass burning or forest fires emitting plumes of ammonia large enough so that they can extend to the free troposphere and be efficiently transported all the way to the Greenland ice sheet. Here we present preliminary results of the wild fire frequency covering the entire Holocene, where the wild fires are defined as outliers in the ammonium record of annual means.
Augmenting the sensor network around Helgoland using unsupervised machine learning methods
Authors: Wichert Viktoria , Brix Holger
Published: March 2020

A sensor network surrounds the island of Helgoland, supplying marine data centers with autonomous measurements of variables such as temperature, salinity, chlorophyll and oxygen saturation. The output is a data collection containing information about the complicated conditions around Helgoland, lying at the edge between coastal area and open sea. Spatio-temporal phenomena, such as passing river plumes and pollutant influx through flood events can be found in this data set. Through the data provided by the existing measurement network, these events can be detected and investigated.

 Because of its important role in understanding the transition between coastal and sea conditions, plans are made to augment the sensor network around Helgoland with another underwater sensor station, an Underwater Node (UWN). The new node is supposed to optimally complement the existing sensor network. Therefore, it makes sense to place it in an area that is not yet represented well by other sensors. The exact spatial and temporal extent of the area of representativity around a sensor is hard to determine, but is assumed to have similar statistical conditions as the sensor measures. This is difficult to specify in the complex system around Helgoland and might change with both, space and time.

Using an unsupervised machine learning approach, I determine areas of representativity around Helgoland with the goal of finding an ideal placement for a new sensor node. The areas of representativity are identified by clustering a dataset containing time series of the existing sensor network and complementary model data for a period of several years. The computed areas of representativity are compared to the existing sensor placements to decide where to deploy the additional UWN to achieve a good coverage for further investigations on spatio-temporal phenomena.

A challenge that occurs during the clustering analysis is to determine whether the spatial areas of representativity remain stable enough over time to base the decision of long-term sensor placement on its results. I compare results across different periods of time and investigate how fast areas of representativity change spatially with time and if there are areas that remain stable over the course of several years. This also allows insights on the occurrence and behavior of spatio-temporal events around Helgoland in the long-term.    

Whether spatial areas of representativity remain stable enough temporally to be taken into account for augmenting sensor networks, influences future network design decisions. This way, the extended sensor network can capture a greater variety of the spatio-temporal phenomena around Helgoland, as well as allow an overview on the long-term behavior of the marine system.
Assimilation of near real-time radar altimetry data into a hydrodynamic model for streamflow and water level forecasting
Authors: Jiang Liguang , Shen Youjiang , Liu Dedi , Madsen Henrik , Bauer-Gottwein Peter
Published: March 2020

Satellite radar altimetry has been widely used in hydrological studies, such as monitoring of lakes and reservoirs, retrieving water level and discharge of rivers, calibration of river models, etc. Sentinel-3 SAR altimeter delivers data at three levels of latency, i.e. near real-time (less than 3 hours after data acquisition), slow time critical (within 48 hours after data acquisition), and non-time critical (typically one month after data acquisition). However, most studies use final products, i.e. non-time critical products of altimetry data for inland water monitoring or hydrological simulations. So far, to the best of our knowledge, no study has been exploiting the value of near-real time satellite altimetry data for hydrological research.

In this study, we first investigate data quality of Sentinel-3 near real-time data against non-time critical product and in-situ data over the Han River in China. Then, we assimilate these data into a 1-D hydrodynamic model, i.e. MIKE Hydro River, to exploit the near-real time altimetry dataset for hydrological forecasting. Specifically, we use the Ensemble Kalman Filter to assimilate altimetry-derived water surface elevation data into MIKE Hydro River model. The model state variable that is updated is the water level defined on the numerical grid of the 1D hydrodynamic model. Observation error estimates are generated from the standard deviations of water levels at each virtual station. Applying this operational forecasting system retrospectively over historical periods, the effect of updating water level at multiple virtual stations on forecast performance is investigated.

Through this study, we gain new knowledge about near real-time altimetry products for hydrological studies. This will be informative for both the hydrology community and satellite data providers.
Metamodeling methods that incorporate qualitative variables for improved design of vegetative filter strips.
Authors: Lauvernet Claire , Helbert Céline , Sudret Bruno
Published: March 2020

Significant amounts of pollutant are measured in surface water, their presence due in part to the use of pesticides in agriculture. One solution to limit pesticide transfer by surface runoff is to implement vegetative filter strips (VFS) along rivers. The sizing of these strips is a major issue, with influencing factors that include local conditions (climate, soil, etc.). The BUVARD modeling toolkit was developed to design VFSs throughout France according to these properties. This toolkit includes the numerical model VFSMOD, which quantifies dynamic effects of VFS site-specific pesticide mitigation efficiency. In this study, a metamodeling (or model dimension reduction) approach is proposed to ease the use of BUVARD and to help users design VFSs that are adapted to specific contexts. Different reduced models, or surrogates, are compared: GAM, Polynomial Chaos Expansions, Kriging, and Mixed-kriging. Mixed-kriging is a kriging method that was implemented with a covariance kernel for a mixture of qualitative and quantitative inputs. Kriging and PCE are built by couple of modalities and Mixed-kriging  and GAM are built considering mixed quantitative and qualitative variables. The metamodel is a simple way to provide a relevant first guess to help design the pollution reduction device. In addition, the surrogate model is a relevant tool to visualize the impact that lack of knowledge of some parameters of filter efficiency can have when performing risk analysis and management.
Calculation of temporally high-resolution scaling factors for the thermospheric density from SLR observations
Authors: Zeitler Lea , Schmidt Michael , Bloßfeld Mathis , Rudenko Sergei
Published: March 2020

The motion of a satellite depends on gravitational and non-gravitational accelerations. A major problem in precise orbit determination (POD) of low-Earth orbiting (LEO) satellites is modelling the thermospheric drag. It is the largest non-gravitational acceleration acting on satellites with altitudes lower than 1000 km and decelerates them. In case of the Swarm satellites with an altitude of around 460 km not considering the drag within a POD would cause an error of around 3 meters per revolution in the along-track direction.

In this study, we present results of DGFI-TUM in the context of the project TIPOD (Development of High-Precision Thermosphere Models for Improving Precise Orbit Determination of Low-Earth-Orbiting Satellites) funded by DFG in the frame of the SPP 1788 ‘Dynamic Earth’. One aim of this project is the computation of scaling factors for the thermospheric density from different satellite observation techniques, such as SLR, DORIS, GNSS or accelerometry. For a joint estimation of thermospheric model parameters the spatial, temporal and spectral content of the different scaling factors have to be analysed and interpreted. For example, accelerometer measurements along the satellite orbit provide scaling factors as point values. In this study we derive scaling factors from SLR measurements which could be interpreted as quasi-point values.

For the POD of LEO satellites, DGFI-TUM’s software package DOGS (DGFI-TUM Orbit and Geodetic parameter estimation Software) is used. It is characterized by the ability to process observations of different space geodetic techniques and to combine their linear parameter estimation systems within a joint Gauss-Markov model.

Here, we estimate scaling factors for the thermospheric density with a time resolution much higher than in our previous studies. Therefore, we use information of short passages from selected spherical satellites above SLR ground stations. Different temporal resolutions for the scaling factors varying from 6 hours down to 5 minutes will be tested and discussed in terms of reliability.
A yellow SWIM service dedicated to aviation and ATM by providing early warnings of volcanic SO2 layer height from TROPOMI and IASI sensors
Authors: Brenot Hugues , Theys Nicolas , Wilson Scott , Clarkson Rory , Clarisse Lieven , Durant Adam , Salerno Giuseppe , Corradini Stefano , Biondi Riccardo , Sievers Klaus , Lerot Christophe , van Gent Jeroen , Smith Sheri , Van Roozendael Michel
Published: March 2020

Volcanic ash and gas is, like sulphur dioxide (SO2), a major risk for air traffic. To mitigate this risk and to improve situational awareness for air traffic management (ATM), we describe a new service using the SWIM (System Wide Information System Management) Yellow Profile – see https://www.eurocontrol.int/publication/eurocontrol-specifications-system-wide-information-management-swim – and aligned with the ATM Information Reference Model (AIRM) as required.

This new service provides early warnings of volcanic SO2 layer height (SO2LH) retrievals from 3 satellite instruments (TROPOMI on board S5P, and IASI-A&-B on board MetOp-A&B). The implementation of this service is enveloped in the framework of OPAS – Operational alert Products for ATM via SWIM – project, a KTN (Knowledge Transfer Network) Engage Catalyst funded project (Thematic Challenge 3; https://engagektn.com) of SESAR JU (Single European Sky ATM Research Joint Undertaking; https://www.sesarju.eu).

We present the TROPOMI SO2LH algorithm and the uses of inverse modelling and external observations from satellites and ground-based DOAS-FLAME instruments to validate TROPOMI SO2LH products for recent eruptions (i.e. Etna in Dec. 2018, Raikoke in June 2019, Ubinas in July 2019, Taal in January 2020). Cross-comparison with the satellite instruments CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization), IASI (Infrared Atmospheric Sounder Interferometer) and with GNSS (Global Navigation Satellite System) radio-occultations, is shown. 

This study will describe the specification of our SWIM service and highlight the point of view of an engine constructor (Rolls-Royce) directly in relation with airlines and ATM, with regard to the objectives of the APOS project. Note that due to engine susceptibility to aerosols, the avoidance of flights through volcanic plumes and SO2 clouds is critical.

The development of our new SO2LH products from TROPOMI contributes to an existing early warning system, so called SACS (Support to Aviation Control Service; http://sacs.aeronomie.be). This system is dedicated to support aviation and ATM, and was recently upgraded in the frame of EUNADICS-AV project (European Natural Airborne Disaster Information and Coordination System for Aviation; http://www.eunadics.eu), with many other alert products related to natural airborne hazard affecting air traffic (e.g. volcanic ash column and layer height, smoke from forest fires and desert dust).
Dynamics of hydrological process in karst systems - stable isotope and geochemical approach
Authors: Perşoiu Aurel , Brad Traian
Published: March 2020

Mid to high-altitude karst terrains in NW Romania are the sole sources of water for the numerous rural communities that dot the area. Due to the combination between the 1) specific hydrologic functioning of karst systems, 2) contamination from agricultural activities and 3) lack of waste water treatment plants, the water used for household purposes is subject to potentially high levels of pollution, with adverse effects on health and general well-being. Water flow through fractured systems is generally thought to be less effective in removing contaminants than flow through porous media, but a limited set of studies have shown that despite the lack of mechanical and chemical cleaning of water, microbial activity could lead to attenuation of pollution. To test this hypothesis, we have devised a two stage-approach in which we first targeted the hydrological functioning of karst systems and than analyzed the potential for microbial-mediated degradation of contaminants. We have investigated five hydrokarst systems (HKS, defined as systems with a point input given by either a ponor or cave and an outlet through springs or caves) in the Apuseni Mountains (Romania, East-Central Europe), by collecting monthly samples of water for three years and analyzing their physical, chemical and microbial characteristics. We present here the results of the stable isotope, physical and chemical analyses of water and discuss the sources of water feeding the HKSs and the transfer times and nature of flow, in order to make inferences on the connectivity between the different components of the HKSs. The stable isotope data indicates a rapid transfer of water through the conduits, with low underground retention times. Chemical and stable isotope data reveals a high degree of mixing between waters that enters the karst systems through pint inputs with diffuse infiltration. The different systems behave differently in terms of interaction with the host rock, in three (of the five) cases limestone being dissolved while in two cases no apparent dissolution takes place. On this hydrologic background, microbial analysis indicates an overall downstream decrease of microorganism diversity, potentially suggesting a natural attenuation of pollution.

 

Acknowledgments. This work was supported by a grant of Ministry of Research and Innovation, CNCS - UEFISCDI, project number PN-III-P4-ID-PCCF-2016-0016 (DARKFOOD), within PNCDI III. The research leading to these results has received funding from the EEA Grants 2014-2021, under Project contract no. 4/2019 (GROUNDWATERISK).
Determination of aerosol optical depth and particulate matter concentrations using routine web cam measurements
Authors: Weihs Philipp , Frisch-Niggemeyer Anita , Schreier Stefan
Published: March 2020

 

Visibility and visual contrast depend on several factors such as aerosol concentration, fog attenuation and humidity as well as gas characteristics. Usually, visibility is determined by observers or by visiometers. Routine web cam photographs of Vienna  have been performed for  2 years from the meteorological measurement platform situated on the roof of one of the buildings of University of Natural resources and Life Sciences overlooking the whole city of Vienna. Photographs are taken every 30 minutes in 6 different azimuthal directions. In the following study, we used routine web cam photographs digitalization to study the correlation between the ratio of some RGB channels as well as intensity fluctuations and the aerosol optical depth and on site particulate matter measurements. We first selected only photographs taken on clear sky days

For ground truth data, we used CIMEL sun photometer data of aerosol optical depth and liquid water content, relative humidity from routine measurements from our measurement platform as well as in situ measurements of particulate matter (PM10) performed by the air quality monitoring network of the city of Vienna.

First, the correlation between the contrast in a horizontal line and the aerosol amounts in the atmosphere and particulate matter concentration as a function of time of the day and azimuthal direction was investigated. We then examined the correlation between the blue to red ratio in a vertical and horizontal line with the aerosol amounts and particulate matter concentration in the atmosphere.

Results obtained showed at some azimuth angles and time of the day correlation coefficient R squared of up to 0.85 between horizontal line contrast and in situ PM 10 and between vertical line blue to red ratio and CIMEL aerosol optical depths measurements.

 
Dissemination of seasonal fire weather information for stakeholders and researchers
Authors: Krikken Folmer , Eden Jonathan , Drobyshev Igor
Published: March 2020

Fire is the primary driving factor of the ecosystem dynamics of many forests, directly affecting the global carbon balance and atmospheric concentrations of the trace gases including carbon dioxide. Recent anthropogenic influence has led to an increase in frequency and impact of wild fires. Hence, it is of vital importance to predict forest fire risk at monthly and seasonal time scales in order to mitigate its impacts, including fire driven dynamics of ecosystem and socio-economic services.

Resilience of the ocean–atmosphere system provides potential for early detection of upcoming fire season intensity. Here, we report on the development of a probabilistic empirical prediction system for forest fire risk on monthly to seasonal timescales across the Northern Hemisphere, using local and large scale climate information as predictors for future fire weather. The fire risk is quantified by the monthly drought code (MDC), which is an established indicator for seasonal fire activity.

The forecasts are disseminated through the KNMI climate explorer, using an interactive online Python application, in order to convey forecast information in a simple and digestible manner. A forecasting page allows for end-users to assess local seasonal fire weather risk, associated forecast skill, and the relation between historical MDC and observed fires. The forecasts are updated monthly throughout the fire season. A research page allows for local and global analysis of the sources of predictability, and characterization of the patterns of spatial and temporal variability of fire weather risk.
The importance of slope correction for studying Greenland ice change using radar altimetry (CryoSat-2)
Authors: Sejan Katarzyna , Wouters Bert , van den Broeke Michiel
Published: March 2020

Satellite radar altimetry is one of the most important tools for monitoring changes in the mass balance of the world's ice sheets. Acquiring long time series of elevation changes is crucial, and the long lifetime of the CryoSat-2 mission has contributed wonderfully to this effort. However, once the CryoSat-2 mission ends, it will be important to bridge the gap between CryoSat-2 and future radar altimetry missions. IceSat2 data can help aid this effort, assuming that the appropriate processing techniques are used to allow the comparison of radar and laser altimetry. Furthermore, different altimetry techniques come with their own pitfalls, in radar altimetry signal penetration into the snowpack introduces ambiguity in the origin of reflected echo, a major issue not present in laser altimetry. It is therefore important to minimize this ambiguity by developing processing algorithms for the radar altimetry form CryoSat-2 mission, with a special attention on relating it to the IceSat2 mission.  

Focusing on Greenland Ice Sheet (GIS), we have developed a processing chain for the estimation of surface elevations and elevation changes from the ESA level-1 product (L1b) Baseline D. As a first step, we investigated the importance of Digital Elevation Model (DEM) in the slope correction algorithm and how it affects the estimated surface elevation.

 

The waveform retracker algorithm was developed following the method by Nilsson (2015) with a range of thresholds in the threshold retracker applied to the waveform. Knowing the estimated range and the altitude of the satellite at the time of the measurement, we calculated the corresponding surface elevation at the point of the wavelet reflection.

We apply a slope correction method by Hurkmans (2012), where displacement from the nadir location in x- and y- directions is calculated using the slope angle and aspect retrieved from a DEM, giving a new set of coordinates that represents the location of the estimated elevation. We use two sets of slope angle and aspect calculated from two DEMs, ArcticDEM Release 7 (Porter et al., 2018) and Greenland Ice Mapping Project (GIMP) DEM (Howat et al., 2017). Both DEMs are similar in terms of optical imagery data source, processing and resolution, however, they have been referenced to different laser altimetry data. We investigate this effect in the slope correction of radar altimetry from CryoSat2 mission.

We checked the two sets of slope correction data using IceSat-2 data (Smith et al., 2019) corresponding to the same time period, and selected by nearest point calculation. We analyze and discuss the differences between IceSat-2 data and CryoSat-2 data with slope correction using GIMP DEM or ArcticDEM.
Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks
Authors: Weinert Sebastian , Bär Kristian , Zimmermann Günter , Sass Ingo
Published: March 2020

Key requirement for geothermal power production are temperatures of at least 100°C, while the obtainable flow-rate mainly controls the economic viability. Many geotectonic settings only provide such reservoir temperatures in depths of 3 km or more. Hydrothermal systems reach such temperatures only in specific geotectonically active settings, e.g. the Upper Rhine Graben or the Molasse basin in Germany, and usually are already under exploration and exploitation. Besides these easily accessible hydrothermal systems, which only make up a small share of the overall geothermal potential, petrothermal systems in crystalline or metamorphic basement rocks provide a much larger and ubiquitous resource. Locating and quantifying these petrothermal potentials is still a challenging task.

A newly developed exploration scheme for petrothermal potentials is proposed and applied to the crystalline basement of the Mid-German Crystalline High in the federal state of Hesse, Germany. The exploration is composed by three tiers and subdivided in an outcrop analogue study, a conceptual geological 3D-structural model and the estimation of petrothermal potentials based on the comprehensive geothermal 3D-model composed as result of the first two tiers.

On the example of the Mid-German Crystalline High basement rocks, the assessment scheme is demonstrated. Therefore, the geological 3D-structural model which is based on geophysical, structural geological and well data is presented. Petrophysical rock properties such as porosity, grain and bulk density, compressional wave velocity but also thermal conductivity and thermal diffusivity are measured on outcrop analogue samples and fed into a custom-made weighting matrix as basis for a multi-criteria decision making system. Together with additional criteria such as reservoir geometry, rock mechanical and structural geological features, qualitative potential assessment is performed. Quantification of the petrothermal potentials will be applied by the volumetric method and assumption of recovery factors for petrothermal systems based on operating systems worldwide.

Petrothermal potentials are displayed in the geological model.
Numerical solution analysis of water flow in porous medium under phase changes due to evaporation
Authors: Arbelaez Gaviria Juliana , Kuraz Michal
Published: March 2020

Evaporation is a dynamic and nonlinear process that incorporates various internal transport mechanisms which is important in the unsaturated zone in arid regions under low soil moisture conditions [1, 2]. The governing equations are formed out of the coupled Richards equation with the heat transport equation, where the boundary conditions originate from the surface energy balance. The purpose of this contribution is to present a numerical model simulating coupled water and heat flow in a porous medium with phase changes due to evaporation. The nonlinear nature of this problem, which originates both from the nonlinear Richards equation and latent heat exchange, which in turn governs the heat gradient, requires a proper temporal discretization in order to maintain numerical solution of sufficient qualities. The net evaporation rate is temperature and water content dependent, where the heat transferred downward by thermal conduction into the soil when the soil surface is warming by solar radiation or conducted back to the surface when the temperature of the top of the soil cools. Evaporation rates from terrestrial surfaces are very common to quantify in terms of energy flow leaving the evaporating surface as latent heat of vaporization of the water vapor. In this contribution, it is presented a numerical implementation of this coupled dynamic process and describes the computational difficulties which arise from this nonlinear process, including a numerical comparison between the common approach for evaluating evaporation in soils by using the Penman-Monteith [3] equation and the coupled water and heat flow modeling approach.

References

[1] Hirotaka Saito, Jiri Simunek, and Binayak P Mohanty. Numerical analysis of coupled water, vapor, and heat transport in the vadose zone. Vadose Zone Journal, 5(2):784–800, 2006.

[2]  Masaru Sakai, Scott B Jones, and Markus Tuller. Numerical evaluation of subsurface soil water evaporation derived from sensible heat balance. Water Resources Research, 47(2), 2011.

[3]  Richard G Allen, Luis S Pereira, Dirk Raes, Martin Smith, et al. Crop evapotranspiration-guidelines for computing crop water requirements-fao irrigation and drainage paper 56. Fao, Rome, 300(9):D05109, 1998.
A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters
Authors: Amin Hadi , Sjöberg Lars E. , Bagherbandi Mohammad
Published: March 2020

According to the classical Gauss–Listing definition, the geoid is the equipotential surface of the Earth’s gravity field that in a least-squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s Global Gravity Models (GGM). Although nowadays, the satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the Mean Earth Ellipsoid (MEE). In this study, we perform joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface, and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e. mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea-level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2s-2 and the semi-major and –minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of the GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3s-2.
Radiative feedbacks in a 1D radiative-convective equilibrium model
Authors: Kluft Lukas , Dacie Sally , Buehler Stefan A. , Schmidt Hauke , Stevens Bjorn
Published: March 2020

Equilibrium climate sensitivity (ECS), the change in surface temperature in response to a doubling of atmospheric CO2, is arguably one of the most important quantities when discussing climate change. Despite major improvements in climate modelling over the last decades, ECS estimates lie within a rather constant range between 1.5-4 K. The cause of this spread is not obvious as the comparison of comprehensive climate models is difficult due to the complexity of their formulations.

 

We are revisiting one of the simplest climate models, one-dimensional radiative-convective equilibrium (RCE). Despite their simple and concise model formulation, RCE models include the most dominant clear-sky radiative feedbacks. In our study, we quantify the strength of the Planck, water-vapor, and lapse-rate feedback by turning them on or off using different model configurations. This method allows us to compare the effect of different model assumptions, e.g. the vertical distribution of water vapor, on the decomposed radiative feedbacks. We find that the interplay of the water-vapor and the lapse-rate feedback is especially affected by the relative humidity in the upper troposphere.

 

The RCE model is run with a state-of-the-art radiation scheme, that is also used in comprehensive  Earth system models. A line-by-line radiative transfer model is used to both verify the performance of the fast radiation scheme, and to attribute changes in the radiative feedbacks to specific regions in the electromagnetic spectrum.

 

In a further step, conceptual rectangular clouds are added to investigate possible cloud masking effects on both the radiative forcing and feedback. A large Monte Carlo ensemble is used to tune the cloud optical parameters in a way that the resulting cloud radiative effect matches satellite observations. Preliminary results suggest a near zero long-wave feedback, in contrast to previous studies.
The role of halogens in the regulation of the oxidative capacity of the Earth’s troposphere in low-polluted environments
Authors: Karam Cyril , Szopa Sophie
Published: March 2020

The oxidative capacity, usually represented by the concentration of OH radicals in the troposphere, regulates the lifetime of reactive compounds injected into the atmosphere by the biosphere and by anthropogenic activities. Recently, naturally emitted halogenated species (I, Br, Cl) have been showed to play a significant role in the consumption of global tropospheric ozone, a primary precursor of the hydroxyl radical. So far, the state-of-the-art chemistry of iodine, bromine, and chlorine has been implemented in a few global chemistry-transport models (GEOS-CHEM, CAM-Chem, TOMCAT, WRF-Chem). The 3D global chemistry-climate model (LMDz-INCA) has been recently updated to consider the chemistry of halogens. We present here the impact of this chemistry on the global oxidant budgets as well as the lifetime of chemically active species. We discuss how this chemistry affects the self-regulation of radicals in present low-polluted atmospheres as well as pre-industrial and future climate scenarios.
SUSFEED - Sustainable feed design applying circular economy principles: the case former food in pig nutrition
Authors: Chiarelli Davide Danilo , Luciano Alice , Fumagalli Francesca , Silvetti Annalisa , Pinotti Luciano , Bocchiola Daniele , Rulli Maria Cristina
Published: March 2020

In developing countries, as a result of increasing per capita GDP (Tilman et al., 2011; FAOSTAT, 2017), we are observing shifts in diets towards increasing consumption of animal products (Pimentel et al., 2008). An example of shifting diet is represented by China, where during the last two decades’ demand for and consumption of animal origin has grown rapidly. Public debates and scientific literature principally focused on how these habits affect the amount of required limited resources, addressing those changes as unsustainable, but which can be the effects of a shift in animal diets? SUS-Feed is a projects founded by Fondazione Cariplo aims at evaluating the effects of substituting conventional cereals with former food products in pig’s diets, by addressing its impacts on growth performance, gut health, pig wellbeing, as well as its sustainability assessment and its implications in natural resources saving. In fact, among others, pigs represent an interesting case study, providing 36% of total meat production (113Mtons worldwide) and 51% of energy from animal products (124kcal/cap/day – global average) (FAOSTAT, 2017).

Pig diet is mainly composed by soybeans and maize, whose harvested area worldwide are rapidly exploding, accounting for 187Mha and 111Mha for maize and soybean in 2013 respectively, creating environmental problems such as water scarcity, deforestation, pollution, fires. In order to assess the potential positive feedbacks of such conversion on natural resources, focus of our presentation, a spatial distributed physically based model is applied in order to quantify water and land saving by introducing former food products and the consequent positive feedback on water scarcity, water pollution and deforestation.