bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection and characterization of microseismicity and its relation with fluids at the Irpinia Near Fault Observatory
Authors: Festa Gaetano , Picozzi Matteo , Adinolfi Guido Maria , Caruso Alessandro , Colombelli Simona , De Landro Grazia , Elia Luca , Riccio Rosario , Scala Antonio , Supino Mariano , Zollo Aldo
Published: March 2020

The Irpinia Near Fault Observatory (NFO) is an EPOS infrastructure located in the Campania-Lucania Region (Southern Italy). Its goal is to characterize the microseismicity and to understand the underlying chemical and physical processes occurring along the fault systems that can potentially generate large earthquakes in the area. The Irpinia NFO is currently composed of ISNet – Irpinia Seismic Network, with associated products and services. ISNet is a local network of 32 accelerometric, short-period and broad band stations, that cover the seismogenic areas related to the main earthquakes that occurred in the region in the last centuries, including the 23 November 1980 , Ms = 6.9 event.  Also, ISNet provides real-time analysis and it represents the prototype network for the testing of early warning systems in Italy.

Here we present tools and techniques to accurately locate and characterize the seismicity within the Observatory. Accurate event detection of weak signals from small magnitude events is based on the coherence of arrival times and migration techniques. This method is then coupled with advanced picking and double differences techniques to accurately locate events with a sub-kilometric scale resolution. Source parameters are thus computed inverting the displacement amplitude spectrum, with a probabilistic approach based on the conjunction of states of information in the data and model spaces. This technique is able to automatically rule out unconstrained solutions, while accounting for correlation among parameters. Source location and characterization is here used to investigate the role of the fluids in the region embedding the fault systems; space and time changes in the medium properties or in the source parameters can be used to detect a deviation from the present mechanical state of the faults owing to changes in fluid pore pressure and migration.

Finally, local dense arrays are used here to improve our capability to detect events within the noise level and to move from a point-source to an extended source description of small events in the area.
Potential risk from the use of mine-contaminated sediments for road and rail embankments: preliminary data from Central Italy
Authors: Lattanzi Pierfranco , Costagliola Pilario , Paolieri Mario
Published: March 2020

Mercury contamination of stream sediments in the Paglia and Tiber river catchments (Central Italy) from the abandoned Monte Amiata mining district has long been documented (Rimondi et al., 2019, and references therein). Along the river courses, fluvial sediments have been quarried for decades to obtain sand and gravel for several industrial uses, including construction of road and rail embankments. Although specific information is not available, there is a high chance that some of this material was used for two major Italian transport routes, the A1 Expressway, and the Alta Velocità (=high speed; AV) railroad.

A preliminary survey was conducted near the city of Orvieto (Umbria region, Central Italy) by taking soil samples in proximity of the embankments of A1 and AV. Both constructions occurred in the 1960s-1970s, when the Monte Amiata mines were still active; specifically, the A1 section Chiusi-Orvieto was completed in 1964, and the AV section Città della Pieve-Roma was completed in 1977. Samples from the embankment of the older railroad Orvieto-Orte (completed in 1874, when mining at Monte Amiata was just beginning) were also taken for comparison.

Samples near the A1 and AV embankments show Hg contents ranging from 1.4 to 9.2 mg/kg, and 2.7 to 5.8 mg/kg, respectively. All these values exceed the limit (1 mg/kg) established by Italian regulations for public green and civil use soil; some also exceed the limit (5 mg/kg) for industrial soil. By contrast, samples from the old railroad show values of 0.3-0.4 mg/kg, below the law limits.

The immediate risk to local inhabitants is deemed low; however, these preliminary results indicate a potential contamination of highway and railroad embankments from mine-impacted sediments, and suggest the opportunity of a more systematic study.

Rimondi V., et al. (2019) – Environmental Pollution 255, 113191
Main knowledge gaps in critical zone processes and behaviour: Extracting information from water quality time-series data and models outputs
Authors: Thomas Zahra , Fovet Ophélie , Zhang Qian , Rajanayaka Channa , Zammit Christian , Gascuel-Odoux Chantal
Published: March 2020

In the last few decades, the degradation of water quality and resulting regulations, such as the European Water Framework Directive, the United States Clean Water Act, and the New Zealand Resource Management Act 1991 have promoted water quality monitoring in terms of parameter richness, spatial density and high temporal resolution. Long-term catchment observatories have been strengthened to gain insight into hydrological and biogeochemical processes. New technologies have been developed and deployed to collect more in situ water quality data at higher frequencies. Thus, water quality monitoring around the world has produced a large amount of data from research catchments but also from national monitoring networks. Despite these efforts, water quality data are highly heterogeneous in terms of targeted parameters, measurement methods, sampling frequencies. Also, accessibility to water samples differ from each hydrological compartment (stream, groundwater, soil water and precipitation). Among water quality time-series, higher sampling frequencies are available for stream water where monitoring is relatively easy to carry out generating a high amount of data. However, groundwater data are rare since monitoring and access is relatively difficult. Also, the aim of monitoring network evolved with time. In fact, networks are usually established for a specific purpose which is changing with time and the questions the network is trying to answer? This raise the issue of spatial and temporal flexibility- multi purpose network and the use of network to support model development which could be seen as a “theoretical” monitoring network.

The objective of this talk is to present a review of methods used for analysing temporal water quality signals and models outputs, based on a panel of examples from few but densely monitored environmental research observatories. Such infrastructures also give an insight into critical zone (CZ) research that help to build a transdisciplinary community to identify the main knowledge gaps in CZ processes and behaviour.
Investigation of marginal distribution and dependence structure of simulated streamflow by a rainfall-runoff model
Authors: Kourakos Vasileios , Iliopoulou Theano , Dimitriadis Panayiotis , Koutsoyiannis Demetris , Kaleris Vassilios , Langousis Andreas
Published: March 2020

Runoff simulation using hydrological models has a key role in water resources
management. Thus, there is a need to investigate how rainfall-runoff models preserve
the stochastic characteristics of real-world streamflow data. It is also useful to compare
the stochastic properties of output with those of input processes (rainfall) and internal
state variables (soil moisture), with focus on marginal distribution tails and long-term
persistence. To this aim, we perform a case study using the ENNS rainfall-runoff model
with real and synthetic rainfall time series, and for all processes we study the marginal
distributions and the dependence structures. In the analyses we use recently developed
stochastic tools such as K-moments and climacograms.
Modelling possibilities of the effects of sewage sludge deposition on ecosystem carbon exchange processes - a case study on arable lands in Southeast Hungary
Authors: Kiss Márton , Barta Károly , Gulyás Ágnes , Krajcsi Emese , Farsang Andrea
Published: March 2020

The recent research and policy efforts on climate change mitigation highlight the need for proper understanding of the effects of many types of land management interventions on greenhouse gas exchange processes. The complexity of carbon and nitrogen cycles, which is the case also for agricultural ecosystems, call for model-based research approaches. These can make the decision-making applications easier as well. The agricultural use of sewage sludge is widespread in many countries. There are a number of case studies about its possible effects on greenhouse gas fluxes under different climatic conditions, but there are not many experiences in relevant model-based assessments. In our contribution, the Biome-BGC MuSo (v.6.) model was used for the investigation of the main characteristics of ecosystem exchange of carbon in arable land of warm dry temperate climate in the Great Plain of Hungary. The Biome-BGC is one of the most widely used biogeochemical models, it is capable of handling different land management activities, have a multilayer soil module and enable a quite detailed ecophysiological parameterization, which make it suitable for the targeted study. The results of laboratory analyses of soil profiles of the study area were used for the parameterization (element contents, organic matter, etc.). The poster presents the first results of the integrated measurement and modelling research work.
Can assimilating snow monitoring information offset the adverse effects of precipitation data scarcity in hydrological modelling applications?
Authors: Abbasnezhadi Kian , Rousseau Alain N.
Published: March 2020

The applicability of the Canadian Precipitation Analysis products known as the Regional Deterministic Precipitation Analysis (CaPA-RDPA) for hydrological modelling in boreal watersheds in Canada, which are constrained with shortage of precipitation information, has been the subject of a number of recent studies. The northern and mid-cordilleran alpine, sub-alpine, and boreal watersheds in Yukon, Canada, are prime examples of such Nordic regions where any hydrological modelling application is greatly scrambled due to lack of accurate precipitation information. In the course of the past few years, proper advancements were tailored to resolve these challenges and a forecasting system was designed at the operational level for short- to medium-range flow and inflow forecasting in major watersheds of interest to Yukon Energy. This forecasting system merges the precipitation products from the North American Ensemble forecasting System (NAEFS) and recorded flows or reconstructed reservoir inflows into the HYDROTEL distributed hydrological model, using the Ensemble Kalman Filtering (EnKF) data assimilation technique. In order to alleviate the adverse effects of scarce precipitation information, the forecasting system also enjoys a snow data assimilation routine in which simulated snowpack water content is updated through a distributed snow correction scheme. Together, both data assimilation schemes offer the system with a framework to accurately estimate flow magnitudes. This robust system not only mitigates the adverse effects of meteorological data constrains in Yukon, but also offers an opportunity to investigate the hydrological footprint of CaPA-RDPA products in Yukon, which is exactly the motivation behind this presentation. However, our overall goal is much more comprehensive as we are trying to elucidate whether assimilating snow monitoring information in a distributed hydrological model could meet the flow estimation accuracy in sparsely gauged basins to the same extent that would be achieved through either (i) the application of precipitation analysis products, or (ii) expanding the meteorological network. A proper answer to this question would provide us with valuable information with respect to the robustness of the snow data assimilation routine in HYDROTEL and the intrinsic added-value of using CaPA-RDPA products in sparsely gauged basins of Yukon.
14C estimation of soil C02 turnover rates in Ultisols with different land use
Authors: Cherkinsky Alexander , Prasad Ravi , Sheng Hong , Brecheisen Zachary , Richter Daniel
Published: March 2020

The CO2 flux from soil is a large and significant flux in most ecosystems and can account for more than 2/3 of total ecosystem respiration. In many cases, CO2 flux from soil is estimated by the eddy covariance technique or by classical chamber method with measures of bulk concentration and isotopic composition of carbon dioxide. Whereas most these studies estimated CO2 flux from the soil surface, we analyzed its concentration and isotope composition directly in soil profiles down to 5m depth.

This experiment was conducted in Sumter National Forest by NSF Calhoun CZO research program. A 10cm diameter auger was used to core up to 5 m depth and capped PVC pipe segments of 750 cm3 volume serve as gas reservoirs, each with two gas impermeable tubes that connected the gas reservoirs. Soil gas reservoirs are installed at 5m, 3m, 1.5m, and 0.5m depths from the soil surface. On a three-week interval, soil gases were extracted with a pump and analyzed in the field for CO2 and O2 concentration with samples collected in Tedlar bags for analysis. The samples were collected in summer 2016 under 3 different land uses: hardwood stands that are taken to be never cultivated; old-field pine stands, which had been used for growing cotton in 19th century and then abandoned; and cultivated sites which were used growing cotton, but for the last 50-60 years for growing corn, wheat, legume, sorghum, and sunflowers.

The radiocarbon analyses in the soil CO2 profile were conducted for the first time. It was discovered that concentration of 14C increased with depth and Δ14C changed from 40-60%o in the top 0.5m to about 80-140 ‰ at 5m depth depending on land use.

 
Reanalysis of Some CLUSTER Bow-Shock Crossings With an Optimized Timing Method
Authors: Chanteur Gérard M.
Published: March 2020

When a shock is moving through a cluster of spacecraft, the normal N to the shock and the velocity of the shock along N can be determined from the crossing times of the different spacecraft assuming that the shock is planar and moves without deformation or rotation during the time interval of the encounter. For a cluster of four spacecraft there are six pairs of spacecraft, each one giving raise to a scalar equation relating the vector position R from the first to the second spacecraft, the normal vector N and the time lag Dt : R.N=VDt. This over-determined system of six equations is solved by computing the pseudo inverse of the matrix M acting on the normal vector on the lhs of the equation. Thus the system is modified by attributing a priori a positive weight to each equation (wj, j=1 to 6) the sum being constrained to 1. Then a statistical ensemble of 6-uplets (wj, j=1 to 6) is built ; for each element of this ensemble we compute the condition number of matrix M and we look for the 6-uplet giving the lowest condition number. This procedure warrants the best accuracy of the pseudo-inverse of M and hence the best estimate of the normal vector N. Adding random perturbations to M and to the time lags allows to estimate the uncertainties on N and V through simulations. This optimized timing method is applied to reanalyze some crossings of the terrestrial bow-shock by CLUSTER and the results are compared to the results obtained by the standard method using the reciprocal vectors defined in the ISSI report SR-008 « Multi-Spacecraft Analysis Methods Revisited » published in 2008. A similar method has been applied to the determination of wave vectors of chorus elements observed by MMS in the inner magntosphere.
Physical modeling of the formation of the microcontinent Jan Mayen
Authors: Agranov Grigory , Dubinin Eugene , Grokholsky Andrey , Makushkina Anna
Published: March 2020

The split between the North American and Eurasian plates began in the Late Pleistocene - Early Eocene (58-60 million years). As the stretching took place, overlapping rift cracks formed. With further evolution, the crack that came from the north fully formed, while the south at that time died out, forming the axis of paleospreading (early Ypresian Age, 49.7 Ma). A hot spot was already functioning near Greenland at that time. In the Priabonian Age (33.1 million years), the hot spot ended under the axis of paleospreading. As a result, the spreading axis jumped (Peron-Pinvidic et al., 2012) creating the Jan Mine main microcontinent and the Kolbeinsain spreading ridge. In addition, the northern branch of the spreading ridge died out and the Aegir paleospreading ridge formed. These raises a number of questions arise:

-What is the mechanism for the separation of the Jan Mine continental block?

-Why did the spreading axis jumped and the Aegir Ridge wither away?

-What is the effect of the Icelandic hot spot on microblock formation?

-Are there similar structures in the world formed through a similar mechanism?

To answer these questions, a physical simulation was performed. Some of these issues were considered in (Muller et al., 2001, Gaina et al., 2003, Mjelde et al., 2008, Mjelde, Faleide, 2009).

Modelling was based on the initial geometry of rift cracks, known oldest magnetic anomalies and existing reconstructions. It showed two possibilities for the formation of the Jan Mayen microcontinent.

The first model is associated with parallel or oblique strike of rift cracks, the oncoming movement of which leads to their overlap, isolation of the microcontinental block, which experienced deformation and rotation.

The second model is associated with the presence of a local heat source (hot spot), the influence of which led to a jump of one branch of the rift towards the hot spot, and to the generation of a significant amount of magmatic material, which could significantly change the initial continental structure of the microblock. The second method, which combines the influence of the overlap zone and the hot spot, showed the best correlation with natural structures.
Measuring river planform changes from remotely-sensed data: A Monte-Carlo approach to assess the impact of spatially-variable geometric error.
Authors: Jautzy Timothée , Herrault Pierre-Alexis , Chardon Valentin , Schmitt Laurent , Rixhon Gilles
Published: March 2020

A majority of European rivers have been extensively affected by diverse anthropogenic activities, including e.g. channelization, regulation and sediment mining. Against this background, the planimetric analysis based on remotely-sensed data is frequently used to evaluate historical planform changes, eventually leading to quantification of migration rates. However, geometric spatially-variable (SV) error inherently associated with these data can result in poor or even misleading interpretation of measured changes, especially on mid-sized rivers. We therefore address the following issue: What is the impact of spatially-variable error on the quantification of surfacic river planform changes?

Our test river corresponds to a 20 m wide meandering sub-tributary of the Upper Rhine, the Lower Bruche. Within four, geomorphologically-diverse sub-reaches, the active channel is digitised using diachronic orthophotos (1950; 1964) and the SV-error affecting the data is interpolated with an Inverse Distance Weighting technique based on an independent set of ground control points. As a second step, the main novelty of our approach consists in running Monte-Carlo (MC) simulations to randomly translate active channels according to the interpolated SV-error. This eventually allows to display the relative margin of error (RME) associated with measured eroded and/or deposited surfaces for each sub-reach through MC simulations, illustrating the confidence level in the respective measurements of our river planform changes.

Our results suggest that (i) SV-error strongly affects the significance of measured changes and (ii) the confidence level might be dependent not only on magnitude of changes but also on their shapes. Taking SV-error into account is strongly recommended, regardless of the remotely-sensed data used. This is particularly true for mid-sized rivers and/or low amplitude river planform changes, especially in the aim of their sustainable management and/or restoration. Finally, our methodology is transferrable to different fluvial styles.
Regime-dependent statistical post-processing of wind speed forecasts
Authors: Allen Sam , Ferro Chris , Kwasniok Frank
Published: March 2020

Raw output from deterministic numerical weather prediction models is typically subject to systematic biases. Although ensemble forecasts provide invaluable information regarding the uncertainty in a prediction, they themselves often misrepresent the weather that occurs. Given their widespread use, the need for high-quality wind speed forecasts is well-documented. Several statistical approaches have therefore been proposed to recalibrate ensembles of wind speed forecasts, including a heteroscedastic censored regression approach. An extension to this method that utilises the prevailing atmospheric flow is implemented here in a quasigeostrophic simulation study and on reforecast data. It is hoped that this regime-dependent framework can alleviate errors owing to changes in the synoptic-scale atmospheric state. When the wind speed strongly depends on the underlying weather regime, the resulting forecasts have the potential to provide substantial improvements in skill upon conventional post-processing techniques. This is particularly pertinent at longer lead times, where there is more improvement to be gained upon current methods, and in weather regimes associated with wind speeds that differ greatly from climatology. In order to realise this potential, however, an accurate prediction of the future atmospheric regime is required.
The mechanism of the origin the NBE (CID) and the initiating event (IE) of lightning due to the volume phase wave of EAS-RREA synchronous ignition of streamer flashes
Authors: Kostinskiy Alexander , Marshall Thomas , Stolzenburg Maribeth
Published: March 2020

In an article by Kostinskiy et al. (2019) proposed the mechanism of the origin and development of lightning from initiating event to initial breakdown pulses (termed the Mechanism). The Mechanism assumes initiation occurs in a region of a thundercloud of 1 km3 with electric field E > 0.4 MV/(m∙atm), which contains, because of turbulence, numerous small “Eth-volumes” of 0.001-0.0001 m3 with E ≥ 3 MV/(m∙atm). The Mechanism allows for lightning initiation by two observed types of initiating events: a high power VHF event called an NBE (narrow bipolar event or CID), or a weak VHF event. According to the Mechanism, both types of initiating events are caused by a group of relativistic runaway electron avalanche particles passing through many of the Eth-volumes, thereby causing the nearly simultaneous launching of many positive streamer flashes, Kostinskiy et al. (2019).

In this report, based on the Meek’s criterion for the initiation of streamers (Raizer, 1991) at different heights of lightning initiation and taking into account the number of all background electrons, positrons and photons of cosmic rays with energy ε < 1012 eV (Sato, 2015) crossing Eth-volumes sizes of Eth-volumes are specified (3∙10-4-3∙10-5 m3). The report also showed that synchronous injection with a high probability of relativistic electrons into such small Eth-volumes requires of relativistic runaway electrons avalanches to be initiated by extensive air showers with energies ε > 1015 eV, which would supply (injected) 105-107 secondary electrons into a turbulent region of a thundercloud with a strong electric field.

References

Kostinskiy, A. Yu., Marshall, T.C., Stolzenburg, M. (2019), The Mechanism of the Origin and Development of Lightning from Initiating Event to Initial Breakdown Pulses arXiv:1906.01033

Raizer Yu. (1991), Gas Discharge Physics, Springer-Verlag, 449 p.

Sato T. (2015), Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS, PLOS ONE, 10(12): e0144679.
The relationship of Western Disturbances to precipitation in the upper Indus River basin
Authors: Baudouin Jean-Philippe , Herzog Michael , Petrie Cameron A.
Published: March 2020

The upper Indus River basin is characterised by heavy precipitation falling near the foothills of the major mountain ranges, during two wet seasons: winter and summer. Winter precipitation is known to be related to the passing of upper-level synoptic systems embedded in the subtropical westerly jet called Western Disturbances. Here, we investigate the precipitation variability in relation to the Western Disturbances at the synoptic scale, using ERA5 reanalysis data. We take advantage of the results of a previous study that showed that the precipitation is mostly triggered by the forced uplift of a low-level moisture-rich southerly flow across the ranges. We show that the low-level southerly wind triggering the precipitation is produced by the interaction of a Western Disturbance with a baroclinic front located between the Iranian plateau and the Arabian Sea. Ahead of the Western Disturbance, low-level winds draw moisture from the extreme north of the Arabian Sea, the Persian Gulf, and to a lower extent, the Red Sea. At the rear, moisture is depleted by the advection of continental dry air in the Indus River basin. However, the balance between moisture drawing and depletion depends on the characteristics of the Western Disturbance, leading to differences in precipitation intensity. We found the jet position and western Russia blockings to play a role in this. These findings offer clues to understand the longer-term precipitation variability in the area.
Equatorial pitch angle distributions in Earth's radiation belts: an empirical model from Van Allen Probes data
Authors: Smirnov Artem , Shprits Yuri , Allison Hayley , Aseev Nikita
Published: March 2020

Earth’s radiation belts comprise complex and dynamic systems, depending substantially on solar activity. The pitch angle distributions (PADs) play an important role for radiation belts modelling, as they yield information on the particle transport, source and loss processes. Yet, many missions flying in the radiation belts provide omni-directional or uni-directional electron flux measurements and do not resolve pitch angles. We propose an empirical model of the equatorial PADs and a method to retrieve PADs from omni-directional flux measurements at different energies and locations along the inclined orbits. We use the entire dataset of MagEIS and REPT instruments aboard the Van Allen Probes (RBSP) mission to analyze the equatorial pitch angle distributions in the energy range from 30 keV to 6.2 MeV. The fitting method resolves all main types of PADs, including butterfly and cap distributions, and the resulting coefficients are directly related to the PAD shapes. The developed model can be used to obtain pitch angle resolved fluxes for GPS, Arase and other missions. The proposed algorithm is applied to the GPS electron flux data set to obtain the pitch-angle resolved fluxes, which are compared to the RBSP data at a number of GPS-RBSP conjunctions. The proposed model also allows one to reconstruct the pitch-angle resolved data using LEO measurements. The dynamics of the fitting coefficients based on solar activity is discussed with respect to AE, Kp, Dst indices and solar wind parameters: velocity, density and dynamic pressure.
Investigation of systematic errors in GRACE temporal gravity field solutions using the Improved Energy Balance Approach
Authors: Uz Metehan , Akyılmaz Orhan , Kusche Jürgen , Shum Ck , Üstün Aydın , Zhang Yu
Published: March 2020

In this study, we investigate systematic errors in our temporal gravity solutions computed using the improved energy balance approach (EBA) (Shang et al. 2015) by reprocessing the GRACE JPL RL03 L1B data product. Our processing consists of two steps: the first part is the estimation of in-situ geopotential differences (GPD) at the satellite altitude using the energy balance formalism, the second part is the estimation of spherical harmonic coefficients (SHCs) of the global temporal gravity field model using the estimated GPDs. The first step includes daily dynamic orbit reconstruction by readjusting the reduced-dynamic (GNV1B) orbit considering the reference model, and estimating the accelerometer calibration parameters. This is coupled with the alignment of the intersatellite velocity pitch from KBR range rate observations. Due to the strategy of using KBR range-rate in our processing algorithm, the estimation of in-situ geopotential differences (GPD) includes both the systematic errors and the high-frequency noise that result from the range-rate observations. Since estimated GPDs are linearly connected with the spherical harmonic coefficients (SHCs) of the global gravity field model, our temporal models are affected by these errors, especially in high-degree coefficients of the temporal gravity field solutions (from n=25 to n=60).

In order to increase our solution accuracy, we fit additional empirical parameters for different arc lengths to mitigate the systematic errors in our GPD estimates, thus improving our temporal gravity field solutions. Our EBA approach GRACE monthly gravity field models are validated by comparisons to the official L2 data products, including the official solutions from CSR (Bettadpur et al., 2018), JPL (Yuan et al., 2018) and GFZ (Dahle et al., 2018).
Climate Observations in 22 African Countries at 550 locations: the TAHMO network
Authors: Selker John , van de Giesen Nick , Annor Frank
Published: March 2020

The Trans-African Hydro-Meteorological Observatory (TAHMO) was officially founded as a not-for-profit foundation in 2014. TAHMO has become the largest provider of scientific weather and climate data for sub-Sahara Africa, with over 500 stations in 22 countries, and a goal of 20,000.  The projection for 2020 is to have 800 stations running and reporting.  TAHMO has successfully shown that it is possible to run a high-quality cost-effective observation network in Africa through investing in relationships, strategic innovation in technology, management, and on-the-ground operations.

 

Technology -TAHMO partnered with METER Group in the co-design of the weather station. Originally, the thought was to develop a very cheap ($200) station, but robustness and accuracy were the driving goals, leading to a station with costs closer to $2000.  Many ideas have been bounced between the two teams and tested in the field in Africa, with no fewer than three generations of technology having been tested.

 

Operation - Over 90% of TAHMO stations are placed at (secondary) schools. This provides physical and, moreover, social protection. Educational material is provided to engage teachers and students and to encourage them to help out with simple maintenance, such as cleaning.

 

Financial sustainability - Stations have been funded through projects funded largely by donors and agencies. A large investment by IBM / Weather Underground formed the basis for a rapid expansion of 333 stations. To ensure long-term financial sustainability, TAHMO provides data services to commercial users, wherein the value chain run from raw data to actionable information. For this reason, TAHMO has become part of a network of entities that bridge the gap between weather station and information market. TAHMO provides data to the research enterprise and host governments at no cost.

 
Re-examining inferences from Hadley cell theory on tropical expansion under global warming throughout the seasonal cycle
Authors: Hill Spencer , Mitchell Jonathan , Bordoni Simona
Published: March 2020

Simulations of global warming in numerical models ranging from full-complexity atmosphere-ocean global climate models (GCMs) to highly idealized, dry, atmospheric GCMs almost invariably feature poleward expansion of the annual-mean Hadley cell extent.  The attendant widening of the subtropical dry zones underlying the Hadley cell descending branches makes understanding this response of the large-scale circulation to climate change of paramount societal and ecological importance.  Two theories, one that neglects the role of large-scale eddy process and one that does not, yield similar but ultimately distinct dependencies of the Hadley cell width on planetary parameters, including those such as the equator-to-pole temperature gradient that also robustly change under global warming.  A common approach, therefore, is to use the responses of these parameters diagnosed from GCM simulations to make arguments about their influence on the Hadley cell widening.  This talk offers a critical examination of that approach.

The approach's key flaw is that the quantities such as the equator-to-pole temperature gradient that appear in the theoretical scalings refer to their values in the *absence* of any large-scale overturning circulation, Hadley cells or eddies, i.e. in the hypothetical state of latitude-by-latitude radiative convective equilibrium (RCE).  This RCE state is what "forces" the Hadley cells, and once the Hadley cells emerge they modify (among others) the equator-to-pole temperature gradient.  Using these theories to understand the Hadley cell response to increased CO2 therefore requires analyzing the responses of the hypothetical RCE state to the increased CO2, which we do via single column model simulations.  In addition, we present a new scaling for the Hadley cell extent applicable to the solsticial seasons that, unlike the existing scalings, does not depend sensitively on the presence or absence of large-scale eddies, which we use in conjunction with solsticial RCE simulations to clarify arguments regarding tropical expansion over the course of the annual cycle in addition to the annual mean.  The implications for these refined theoretical arguments on results from prior studies and on constraining future Hadley cell expansion are discussed.
AI4GEO: An automatic 3D geospatial information capability
Authors: Baillarin Simon , Brunet Pierre-Marie , Lassalle Pierre , Souille Gwenael , Gabet Laurent , Foulon Gilles , Romeyer Gaelle , Ferrero Cedrik , Huynh Thanh-Long , Masse Antoine , Assier Stan
Published: March 2020

The availability of 3D Geospatial information is a key stake for many expanding sectors such as autonomous vehicles, business intelligence and urban planning.

The availability of huge volumes of satellite, airborne and in-situ data now makes this production feasible on a large scale. It needs nonetheless a certain level of skilled manual intervention to secure a certain level of quality, which prevents mass production.

New artificial intelligence and big data technologies are key in lifting these obstacles.

The AI4GEO project aims at developing an automatic solution for producing 3D geospatial information and offer new value-added services leveraging innovative methods adapted to 3D imagery.

The AI4GEO consortium consists of institutional partners (CNES, IGN, ONERA) and industrial groups (CS-SI, AIRBUS, CLS, GEOSAT, QWANT, QUANTCUBE) covering the whole value chain of Geospatial Information.

With a 4 years’ timeline, the project is structured around 2 R&D axes which will progress simultaneously and feed each other.

The first axis consists in developing a set of technological bricks allowing the automatic production of qualified 3D maps composed of 3D objects and associated semantics. This collaborative work benefits from the latest research from all partners in the field of AI and Big Data technologies as well as from an unprecedented database (satellite and airborne data (optics, radars, lidars) combined with cartographic and in-situ data).

The second axis consists in deriving from these technological bricks a variety of services for different fields: 3D semantic mapping of cities, macroeconomic indicators, decision support for water management, autonomous transport, consumer search engine.

Started in 2019, the first axis of the project has already produced very promising results. A first version of the platform and technological bricks are now available.

This paper will first introduce AI4GEO initiative: context and overall objectives.

It will then present the current status of the project and in particular it will focus on the innovative approach to handle big 3D datasets for analytics needs and it will present the first results of 3D semantic segmentations on various test sites and associated perspectives.
The role of vegetation in the redistribution of infiltration in a semi-arid zone
Authors: Garcia Perez Ana Berenice , Gonzalez Sosa Enrique , Breil Pascal , Braud Isabelle
Published: March 2020

The effect of vegetation on the volumes of water that infiltrates into the soil has been extensively studied, but not the redistribution that occurs radially from trees. This is especially important in arid and semi-arid areas where water volumes are scarce and water resources management must be more scrupulous. In the present study, the influence of native vegetation (huizache trees) on the redistribution of infiltration in a semi-arid zone in the central Mexican plateau was analyzed. Single ring infiltration tests were carried out with a radial distribution in 2 trees: 4 located inside the crown of the tree and 4 outside it, in 4 different axes, giving a total of 32 tests per tree. Likewise, particle size distribution and soil texture analysis were carried out in 4 orthogonal directions and dry bulk density and initial water content tests at each sampling point were performed. The results showed a zone of influence located between r / 2 and r of the tree canopy, where the infiltration is much greater compared to the other points. Based on these results, the methodology for a third tree was redesigned, in order to characterize various infiltration areas. So that 3 zones were established within the tree: near, intermediate and far, taking 2 tests in each zone, in orthogonal direction, and taking a test in each zone of 4 additional axes, a total of 36 tests. The results of the infiltration tests with this methodology showed similar results to the other two trees: low infiltration rates close to the tree trunk, high infiltration rates in the area between r / 2 and r of the canopy and again low rates of infiltration in the area outside the crown. Additionally, the particle size distribution analyzes showed the presence of 4 types of soil: loam, sandy-loam, clay-loam and silt-loam soil. On the other hand, the initial water content and dry bulk density do not seem to affect the infiltration process to a greater extent and they vary indiscriminately. The above suggests that the area between r / 2 and r is the one that captures the highest infiltration volumes, it may be due to the shadow effect produced by the treetops, although the soil texture has an influence on the infiltration rates, it does not influence the form of radial redistribution of tree infiltration.
Variational Model Reduction for Rotating Geophysical Flows with Full Coriolis Force
Authors: Özden Gözde , Oliver Marcel
Published: March 2020

Consider the motion of a rotating fluid governed by the Boussinesq equations with full Coriolis parameter. This is contrary to the so-called ''traditional approximation'' in which the horizontal part of the Coriolis parameter is zero. The model is obtained using variational principle which depends on Lagrangian dynamics. The full Coriolis force is used since the horizontal component of the angular velocity has a crucial role in that it introduces a dependence on the direction of the geostrophic flow in the horizontal geostrophical plane. We aim that singularity near the equatorial region can be solved with this assumption. This gives a consistent balance relation for any latitude on the Earth. We follow the similar strategy to that Oliver and Vasylkevych (2016) for the system to derive the Euler-Poincaré equations. Firstly, the system is transformed into desired scale giving the differences with the other scales. We derive the balance model Lagrangian as called L1 model, R. Salmon, using Hamiltonian principles. Near identity transformation is applied to simplify the Hamiltonian. Whole calculations are done considering the smallness assumption of the Rossby number. Long term, we aim that results help to understand the global energy cycle with the goal of validity and improving climate models.
Site-scale estimation of Ozone in Northern Bavaria using Gradient Boosting Machines, Deterministic Regional Air Quality Models and a Hybrid Model
Authors: nabavi seyed omid , Nölscher Anke , Haimberger Leopold , Cuesta Juan , Thomas Christoph , Held Andreas , Samimi Cyrus
Published: March 2020

This study is part of the Mitigation of Urban Climate and Ozone Risks (MiSKOR) project. MiSKOR aims to use a collection of tools to mitigate the problems of the urban heat island effect and ozone (O3) pollution in and around medium sized cities in northern Bavaria (NB).  In this study, we developed modelling tools to estimate (hindcast), classify (O3 >= 120 ug/m3 or O3 < 120 ug/m3), and forecast hourly O3 concentrations at nine unmonitored sites in NB. Three machine learning algorithms (MLAs) including linear- and tree-based eXtreme Gradient Boosting Machines (MLR-XGBM and Tree-XGBM) and logistic regression (LR) are used for O3 modelling. MLAs are trained by using hourly observations of O3 and its chemical and meteorological precursors from seven monitored sites in NB. In addition, the daily average of surface O3 observations along 6-hour back trajectories, produced by HYSPLIT model, is fed into MLAs to provide a rough estimation of O3 transport in a local scale. MLAs are compared with two state of the art regional deterministic models (DMs) namely the ECMWF Copernicus Atmosphere Monitoring Service (CAMS) regional air quality model for Europe (CAMS-EU) and the DLR WRF-POLYPHEMUS air quality system (used only for O3 forecast purpose). Finally, we created a new hybrid model by combining the O3 estimations from the best MLA model and the regional air quality model CAMS-EU.

According to averaged metrics from leave-one-site-out cross-validation (LOOCV), MLR-XGBM outperformed other models in the estimation of O3. This model yielded summertime RMSE and Spearman correlation coefficient (SCC) of 13.6 µg/m3 and 0.91 respectively. Interestingly, the hybrid model significantly improved the accuracy of O3 estimations. It reduced the summertime seasonal RMSE to 11.4 µg/m3 and increased the lowest seasonal SCC to 0.95. MLR-XGBM also yielded the best performance in O3 forecast compared to CAMS-EU and WRF-POLYPHEMUS. With regard to O3 classification LR outperformed other models. We also found that using remotely sensed lower troposphere O3, from IASI/GOME2, improves the classification of high extreme O3 in summertime.
Forced monsoon rainfall changes and the moist static energy budget: the Sahel and elsewhere
Authors: Hill Spencer
Published: March 2020

The Sahel is the semi-arid, transitional region separating the Sahara Desert from humid equatorial Africa, i.e. the poleward-most region to which appreciable rains from the West African monsoon extend during northern summer.  The severe drought it experienced in the 1970s and 1980s was one of the 20th century's most striking (and devastating) hydroclimatic events worldwide.  In climate model simulations of future global warming, Sahelian rainfall does anything from intense drying to even greater wettening depending on which climate model is used.  In this talk, I present recent research on rainfall in the Sahel using the moist static energy (MSE) budget -- what are the physical factors that drive its variations, and how do we expect them to change as the planet warms --- and the extent to which inferences from the Sahel can or cannot extend to other regions and other external forcings.

Using climate model simulations both of Earth's present-day conditions and of future global warming, I show that the drying influence of the Sahara Desert is a dominant factor in present-day and that this influence is strengthened with warming due to an increasing difference in moisture between the desert and the Sahel.  This enhancement of an existing moisture (and energy) gradient is a robust response of the atmosphere to mean ocean surface warming and has a firm theoretical basis.  By comparing climate model simulations of the present-day Sahel climate to real-world observations, I argue that this Sahara-driven drying mechanism is overly strong in those models that dry the Sahel most in future simulations.  This response to mean warming of global sea surface temperatures (SSTs) is readily explained using the MSE budget, whereas the Sahel rainfall response to changes in the spatial pattern of SSTs (such as during the 1970s-80s drought) are more easily interpreted via the popular energetic framework for Intertropical Convergence Zone (ITCZ) shifts.  I discuss the interplay between these and other theoretical frameworks for forced monsoon rainfall changes in the Sahel and other monsoon regions and offer ideas for refining and extending those theories.
Assessment of the measuring errors in tipping rain gauge located on a small mountain basin
Authors: Rodriguez-Sinobas Leonor , Segovia-Cardozo Daniel Alberto , Zubelzu Sergio , Estefania Enrique , Díez-Herrero Andrés
Published: March 2020

Precipitation measurement has always been of human interest. Its estimation can guide the decisions concerning flooding prevention and irrigation scheduling in semi-arid regions.

Nowadays, manufactures offer several types of rain gauges. Among them, the tipping-bucket rain gauges (TBRs) is the most frequently used worldwide to collect rainfall data. It structure is simple and the manufacturing cost is reasonable. Also, the operating mechanical mechanism saves energy and can be easily automated. Its manufacture began in the seventeenth century although the recent models have improved their original characteristics.

Likewise, these gauges have some disadvantages such us: measurement errors, that can be significant during heavy rainfall or light drizzle; losses from evaporation and wind effects; time of onset; sampling procedure and rain residue in the bucket. Therefore, calibration is often needed.

This study assesses the data from a set of 12 TBRs spread in the small mountain basin “Venero Claro”, Avila (Spain). This is highly monitored due to its capacity to generate torrential flows and flash floods.  The data comprised a time interval of 14 years; the oldest TBRs were installed in 2006. The objective was quantified the errors, especially those caused by high precipitation intensities, which are common in the area. Thus, calibration curves for data analysis were estimated by a dynamic laboratory calibration for two different TBRs’ models.

The results from the calibration data have been statistically analysed in order to determine the errors and their significance along time and topography. A significant underestimation was observed in TBRs, especially in those located at higher areas.