bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine Learning for Understanding Lab Earthquake Prediction and Precursors 
Authors: Marone Chris
Published: March 2022

I summarize a broad suite of laboratory data sets showing that stick-slip failure events –lab earthquakes– are commonly preceded by both measurable changes in fault zone properties and acoustic emission (AE) events that foretell catastrophic failure.  These works show that both types of data can be used to predict labquakes with machine learning (ML) methods and deep learning (DL) approaches.  The first works used continuous measurements of AE to predict the timing of labquakes and the fault zone shear stress. Subsequent studies showed that catalogs of AE events could also predict labquakes and that ML approaches could also predict stress drop, peak fault slip velocity and the duration of failure. Recently, DL has been used to predict and autoregressively forecast labquakes and fault zone shear stress. Consistent with previous works, we see that seismic b-value begins to decrease as faults unlock and start to creep.  This provides a sensible connection between the ML-based predictions, fault zone elastic properties, and the physics of failure.  In the lab, AE events represent a form of foreshock and, not surprisingly, the rate of foreshock activity correlates with fault slip rate and its acceleration toward failure.  Our work shows precursory changes in wave speed prior to labquakes, consistent with many well known past studies, but the early studies did not provide a method to predict impending failure.  ML and DL predicts with fidelity the time of impending failure and other aspects of it. This suggests the possibility of physics-based models for prediction. We are working to connect ML prediction of labquakes with the evolution of fault zone elastic properties, frictional contact mechanics and constitutive laws.  A central goal is to learn from lab earthquake prediction to improve forecasts of earthquake precursors and tectonic faulting.
Visualising and quantifying momentum transport in cloudy boundary layers using collocated lidar and cloud radars
Authors: Dias Neto José , Nuijens Louise , Unal Christine , Knoop Steven
Published: March 2022

Convective clouds may be associated with substantial transport of momentum. The process of convective momentum transport is typically investigated using simulations due to a lack of observations. This study exploits the currently available remote sensing techniques to visualize wind structures within clouds and their surroundings and quantify the vertical transport of momentum.

The Tracing Convective Momentum Transport in Complex Cloudy Atmospheres experiment (CMTRACE) took place in the experimental site in Cabauw (The Netherlands) between September 13th and October 3rd 2021, as part of the RUISDAEL project. The goal of CMTRACE was to provide continuous profiles of horizontal and vertical wind components with a temporal resolution of ~1 minute and vertical resolution of ~50 m within the cloud and sub-cloud layers to improve our understanding of the role of momentum transport on different scales. One scanning wind lidar provided the observations in the sub-cloud layer, while in the cloud layer, the observations were obtained by one scanning and one vertically pointing cloud radar. The high-resolution data produced by those instruments across the boundary layer can also benefit data assimilation and model evaluation.

During CMTRACE, we sampled various cloud regimes such as non-precipitating shallow cumulus, deep convective clouds and stratiform clouds. Due to the presence of insects, the radar provided almost identical wind profiles to the lidar up to cloud base, giving us confidence in the quality of the observations. The dataset was also validated against the data from radiosondes and the Cabauw mast tower.

In this presentation, we outline the CMTRACE observational dataset and present statistical analyses and classification of the data into different cloud regimes. The profiles of wind fluctuations and momentum fluxes are used to exemplify correlations between vertical and horizontal wind on both cloud- and mesoscale scales.
A novel parameterization for wildfire plumes in LPJ-GUESS
Authors: Nieradzik Lars , Bergman Tommi
Published: March 2022

Wildfires are one of the major disturbances in the global terrestrial ecosystems and can be the key driver for both vegetation composition and structure, affecting the carbon stocks above and below the surface. With a total of about 2 Pg(C)/year emitted into the atmosphere wildfires also play an important role in the global carbon cycle. Beyond this, emissions from wildfires influence regional air quality, can have a fertilizing effect on the surroundings, or alter the albedo of both the burned area itself but also of distant areas when e.g. black carbon is deposited on ice sheets or snow. Large fires creating pyrocumulonimbus-clouds even elevate trace gases into the lower stratosphere. 

The chemical and physical evolution of the compounds emitted by wildfires can be simulated by modern CTMs (Chemistry Transport Models) and ESMs (Earth-System Models). A key uncertainty in these models, though, are the fires and the resulting emissions themselves, both in space and amount. Many plume rise models use satellite retrievals for fire intensity as e.g. FRP (Fire Radiative Power) and top height for hindcast or historical simulations, where the accuracy of FRP is anti-correlated with the total emissions because the plume itself blocks the frequencies needed to measure a fire’s intensity, i.e. the larger in scale a fire is the less accurate its intensity, and therefore, it is difficult to generate a vertical emission profile. Furthermore, for future projections, these parameters need to be computed from available information within the operating model.

The approach presented here was developed in the framework of the project CoBACCA and is an attempt to invert this problem. Therefore, we use the 2nd generation dynamic global vegetation model LPJ-GUESS and its incorporated wildfire-model SIMFIRE-BLAZE. Vegetation in LPJ-GUESS is represented by 12 different Plant Functional Types (PFTs; 10 tree and 2 grass PFTs) plus litter and soil pools. In combination with meteorological parameters, the combustion model BLAZE then computes their mortality, their combustion completeness, the intensity of the fire, and finally a vertical emission profile. 

Another critical issue for the use of vertical emissions is that one of the uncertainties in atmospheric models is the height of the planetary boundary layer (PBL) which more or less determines whether emitted air-parcels remain in the mixing layer or reach the free troposphere or even the lower stratosphere. We, therefore, decided to compute the vertical emission profile relative to a model-generated PBL.

These emission profiles will be used online in the upcoming version 4 of the ESM EC-Earth but they can also be used offline as emission inventories for other models. This is a step towards a fully coupled plume-rise sub-grid model to be developed within EC-Earth4.
HERMES: HEmera Returning MESsenger
Authors: Romeo Giovanni , Iarocci Alessandro , Spinelli Giuseppe , Di Stefano Giuseppe , Lepore Amedeo , Adobbato Pasquale , Masi Silvia , Bacci Simone
Published: March 2022

Stratospheric long-duration balloons (LDBs) are a cheap and easy way to access the near space, allowing geophysical and cosmological observations.

A common issue for LDBs  is the high bit rate data transferring. Just few hours after launch balloons are nor reachable with direct radio link, and satellite links are, simply, too expensive.  For this reason the satellite link is used only for house keeping and remote control, and scientific  data are recorded on board.   This makes  mandatory to recover the payload to get the observation’s results, a difficult task operating in polar areas, impossible  during the polar winter.

The aim of the project is to provide an autonomous glider capable of physically carrying data and samples from the stratospheric platform to a recovery point on the ground. The glider itself  can also transport instruments and can make measurements during the flight. We estimate that an electrical motorglider released in the stratosphere can fly for several hundreds kilometres.

The glider  is installed on the balloon payload through a remotely controlled release system (which provides its own direct radio link  and satellite communications), and connected to the main computer to receive data and geographic coordinates of the recovery point. The glider trajectory can be monitored with Iridium SBD, and remotely controlled using Iridium too.

The glider is a carbon fiber reinforced foam structure, a compact and robust design, self-stable, which has been shown to steer correctly in the lower stratosphere.

Several test have been conducted with motorized and non motorized gliders,   showing  that the presence of the engine helps the aircraft to get into flight attitude, at around 20 km of altitude, compared to 10 km achieved in non-motorized flights.
GAN-based video prediction model for precipitation nowcasting
Authors: Ji Yan , Gong Bing , Langguth Michael , Mozaffari Amirpasha , Mache Karim , Schultz Martin , Zhi Xiefei
Published: March 2022

Detecting and predicting heavy precipitation for the next few hours is of great importance in weather related decision-making and early warning systems. Although great progress has been achieved in convective-permitting numerical weather prediction (NWP) over the past decades, video prediction models based on deep neural networks have become increasingly popular over the last years for precipitation nowcasting where NWP models fail to capture the quickly varying precipitation patterns. However, previous video prediction studies for precipitation nowcasting showed that heavy precipitation events are barely captured. This has been attributed to the optimization on pixel-wise losses which fail to properly handle the inherent uncertainty.  Hence, we present a novel video prediction model, named CLGAN, embedding the adversarial loss is proposed in this study which aims to generate improved heavy precipitation nowcasting. The model applies a Generative Adversarial Network (GAN) as the backbone. Its generator is a u-shaped encoder decoder network (U-Net) equipped with recurrent LSTM cells and its discriminator constitutes a fully connected network with 3-D convolutional layers. The Eulerian persistence, an optical flow model DenseRotation and an advanced video prediction model PredRNN-v2 serve as baseline methods for comparison. The models performance are evaluated in terms of application-specific scores including root mean square error (RMSE), critical success index (CSI), fractions skill score (FSS) and the method of object-based diagnostic evaluation (MODE). Our model CLGAN is superior to the baseline models for dichotomous events, i.e. the CSI, with a threshold of heavy precipitation (8mm/h), is significantly higher, thus revealing improvements in accurately capturing heavy precipitation events. Besides, CLGAN outperforms in terms of spatial scores such as FSS and MODE. We conclude that the predictions of our CLGAN architecture match the stochastic properties of ground truth precipitation events better than those of previous video prediction methods. The results encourage the applications of GAN-based video prediction architectures for extreme precipitation forecasting.
Soil moisture bimodality over Land–Atmosphere hotspot regions at intraseasonal and interannual timescale.
Authors: Dengri Abhinav , Yamada Tomohito
Published: March 2022

This study examined boreal summer soil moisture using long-term satellite observations to study the bimodal probability distribution function (bimodality) of the surface soil moisture for the land-atmosphere coupling hotspot region, i.e., United States, Sahel and India. Although boreal summer soil moisture bimodality has been detected globally, it has not yet been established how surface soil moisture bimodality is caused. In this comparative multiregional study of surface soil moisture, the object was to classify India, Sahel, and Unites States regions into inter-annual or intra-seasonal soil moisture variation-based soil moisture bimodality. It was found that soil moisture bimodality detection is sensitive to the number of observations and the selected time period window. For northern India, intra-seasonal soil moisture variation dominates for soil moisture bimodality, while in the case of the United States, intra-annual soil moisture variation is dominant. 
Towards a national susceptibility map for rock avalanches
Authors: Böhme Martina , Morken Odd Andre , Oppikofer Thierry , Hermanns Reginald L. , Penna Ivanna , Nicolet Pierrick , Bredal Marie , Pullarello José , Noël Francois
Published: March 2022

Several rock avalanches with significant consequences have taken place in Norway during the last centuries. This has caused a high awareness with respect to this natural hazard. As a result, mapping of unstable slopes was initiated in 2006 and several high-risk unstable rock slopes have been identified and investigated in detail and today are monitored. Furthermore, the mapping program of unstable rock slopes has become systematic. Under this initiative, so far five out of eleven Norwegian counties have been analysed systematically for unstable rock slopes and the mapping has been completed for one of these counties. Registered slopes are mapped and classified based on a systematic hazard and risk classification system, established in 2012. This process is time intensive, and currently attention might not be given to the highest risk objects.

In order to get a rapid, complete national overview of potential large rock slope failures, as well as their total hazard and consequence potential, a national overview mapping project has been started. This will make it possible to better prioritize high risk objects in the systematic mapping program. The project will be divided into several steps: (1) systematic analysis of remote sensing data (e.g. detailed DEM, orthophoto and InSAR data) to locate potential unstable rock slopes; (2) a simplified hazard ranking; (3) semi-automated volume estimation; (4) automated run-out assessment; (5) and empirical displacement wave run-up height assessment.

In order to minimize the area that needs to be analysed in Step 1, presently known unstable rock slopes have been analysed. Results indicate that the study area can be restricted based on available relief, presence of inhabitants and distance to the shorelines (fjords and lakes). This makes it possible to reduce the study area significantly, from the total land area of Norway down to roughly one third of this. Furthermore, for this quick overview assessment we use a simplified hazard ranking that is based on signs of activity, visible grade of development and its volume.

The resulting susceptibility map will serve as a source to prioritize mapping and mitigation efforts, with respect to other natural hazards in Norway as well.
Quantifying the basal accretion-induced erosion rate variability – A numerical landscape evolution modeling approach
Authors: Das Sayan , Scherler Dirk , Mandal Sanjay Kumar
Published: March 2022

The Late Cenozoic growth of the Himalaya is mainly thought to be a result of basal accretion due to duplexing at the subsurface. However, over geological time, the complex nature of the response of Himalayan topography and erosion rates to the basal accretion along the Main Himalayan Thrust (MHT) fault remains ambiguous. Mandal et al. 2021 hypothesized that the punctuated basal accretion along the MHT brings the landscape out of equilibrium and results in periodic temporal variations in erosion rates. We seek to build on this idea by exploring the growth of the topography and resulting erosion rates due to long-term basal accretion processes along the MHT.  To simulate the changes in topography and consequent variation in precipitation pattern, we are linking an orographic precipitation model (Hergarten & Robl, 2021) to the landscape evolution model used in Mandal et al. 2021. We introduce a migrating zone of high uplift (HUZ) in the model landscape, where the uplift rates are ~5 times greater than the background uplift rate. The orographic precipitation model works by controlling the influx of water in the cells of the model space and subsequently distributing the water volume based on the changes in topography due to overall surface uplift patterns. We calculate the spatially-averaged erosion rates, integrated over the time step length, by considering the uplift rate and the elevation difference between the previous time step and the current, updated elevation grid. In Mandal et al. 2021, feedbacks among the basal accretion-driven rock uplift, river steepening, and erosion rate were observed with the upstream migration of knickpoints and the migration of the ramp over time. With the introduction of the orographic precipitation model, we aim to understand the coupling between duplex-induced growth of the topography and rainfall variation and consequent temporal variability in erosion rates. 
Annual and seasonal shore morphodynamics of a Cuspate Foreland: Les Grands Sables (Groix Island, France) 
Authors: Sedrati Mouncef , Drean Laura , Bulot Glen
Published: March 2022

Studies on the dynamics of convex beaches "Cuspate foreland" have shown that these formations are directly influenced by the joint action of climatic-oceanic and meteorological-marine forcing conditions such as wind, swell, tide and associated currents. They are very dynamic beaches that can migrate longitudinally over a few to hundreds of meters, as well as flatten or lengthen in response to variable weather and sea forcing. These cuspate foreland beaches may also manifest seasonal cycles of beach erosion and recovery driven by the bi-directional approaches of wave climates or by the seasonal changes in swell and wave patterns. 

The "Grands Sables" beach on the island of Groix in the Morbihan - France is one of the most famous convex beaches in Europe. This beach is located to the north of the Pointe de la Croix, the eastern tip of the island of Groix. This beach, extending over nearly 800m, is located on a coastline formed by low cliffs extended to the south by the wide rocky plain. This work describes the seasonal morphodynamics of the Grands Sables cuspate foreland over a period of three years. and three-dimensional beach changes were measured and coupled to wave energy and wind conditions. Thus, the winter seasons, dominated by a strong westerly swell component, favour the movement of the beach towards the south. The summer seasons, on the other hand, allow the beach to find a state of stability between the north-east quarter winds and the south-west/south-east quarter winds, which compensate each other. These north-east quarter winds, which are frontal to the coastline, are also the driving force behind the morphological changes in the beach profile. They contribute to the cross-shore remobilisation of sediments in the intertidal domain, directly at the top of the beach and indirectly below the MHWL level through the action of the swell. In addition to seasonal variations, exceptional storm events also contribute to the southward or northward migration of the beach. During these events, the direction of beach movement is based on the incidence of wave and wind climate in relation to the orientation of the coastline. Results indicate that energetic waves play a significant role in shoreline dynamics and Grands Sables landform shape. Seasonal or high-energy event-driven morphological changes of the beach have occurred without a significant loss of local sedimentary stock.

The findings of this study have improved the understanding of seasonal and multiannual cuspate foreland morphodynamics, setting the groundwork for a potential long-term evolution model of Les Grands Sables beach. 
The new coupled land surface model HUMBOL-TD - Concept and performance
Authors: Limberger Oliver , Dantas De Paula Mateus , Windhorst David , Trachte Katja , Breuer Lutz , Hickler Thomas , Bendix Jörg
Published: March 2022

The megadiverse Andean mountain rain forests in southern Ecuador are threatened by climate and land use change, which are expected to alter biodiversity and thus functional traits impacting ecosystem processes. However, the high biodiversity of tropical mountain forests is still poorly represented in Land Surface Models (LSMs). We developed a biodversity-informed LSM entitled HUMBOL-TD (Hydroatmo Unified Model of Biotic interactions and Local Trait Diversity) to analzye the impact of climate and land-use change on carbon- and water fluxes. HUMBOL-TD consists of three coupled submodels specialized to represent different processes at the land surface. As such, energy- and water fluxes between land surface and atmosphere (LSMatmo) are simulated by the Community Land Model (CLM), vegetation dynamics including C, N and P cycling (LSMbio) are simulated by the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS), while the soil hydrology (LSMhydro) is represented by the Catchment Modeling Framework (CMF). A first test towards the simulation of the mountain forests and their replacement systems is conducted for a pasture site at 2000 m elevation. The model is parameterized and validated using a year of local site data. The first runs of the model enable the investigation of the differences in accuracy of modeled changes in the carbon- and water fluxes between coupled, partially coupled (LSMatmo – LSMbio, LSMatmo – LSMhydro, LSMbio – LSMhydro) and the fully coupled model (LSMatmo – LSMbio – LSMhydro).
Surface wave detectability of transition zone anisotropy induced by non-Newtonian mantle flow
Authors: Magali John Keith , Merkel Sébastien , Ledoux Estelle
Published: March 2022

Large-scale anisotropy inferred from long-period seismic tomography mainly results from the crystallographic preferred orientation (CPO) of olivine aggregates due to mantle deformation. In the 410-km transition zone, the inclusion of wadsleyite CPO diminishes the overall anisotropy. This may predispose the latter below the seismic detection limit.  In this study, we attempt to assess the detectability of the anisotropy in the 410-km transition zone using surface wave dispersion measurements. Proceeding as a purely-forward approach, we consider non-Newtonian mantle flows reminiscent to the deformation by dislocation creep of olivine. A wadsleyite layer is imposed underneath the discontinuity down to a depth of 520 km. We model the CPO development in olivine and in wadsleyite using a visco-plastic self-consistent (VPSC) approach. Finally, we compute local surface wave dispersion curves and its azimuthal variations to study the surface imprint of transition zone anisotropy.  We anticipate the sensitivity kernels to as well provide key insights in evaluating its detectability.
The effect of magnetic field direction during the low-temperature oxidation of titanomagnetite bearing TRM on paleointensity determinations
Authors: Grachev Roman
Published: March 2022

In this study, we have carried out a laboratory simulation of the low-temperature oxidation (below Tc) of titanomagnetite carrying a primary thermoremanent magnetization (TRM) created in Blab=25-50 µT. The initial material was natural basalt P72/4 from the Red Sea rift zone containing unoxidized (degree of oxidation Z =0) titanomagnetite with ulvöspinel content x=0.5 (Fe2.5Ti0.5O4).

Cubic basaltic samples containing titanomagnetite were annealed in air in weak field Ban=50-100μT at temperature Tan=260 Cfor maximum time t=1300 hours. One group of samples were annealed in the magnetic field perpendicular (Ban⊥TRM) and other parallel (Ban∥TRM) to the primary TRM. Thellier's-Coe double-heating method in argon atmosphere were conducted using all samples with different Z.

As for Ban∥TRM, the calculated field value (Bcalc) obtained from Thellier-Coe’s procedure coincided with the laboratory field (Blab) for all annealing times except t=1300 hours. This result indicates the applicability of the Thellier-Coe method of paleointensity determination on basalt containing titanomagnetite of low and medium degrees of oxidation (Z<0.5).

However, inadequate results were obtained from samples annealed in a magnetic field perpendicular to primary TRM(Ban⊥TRM). In this case, the calculated value of the Bcalc field for t=12 hours are overestimated by ~40%, and for t=400 and 1300 hours is underestimated by ~20% relative to the TRM creation field.

We conclude that reliability of paleointensity data of oxidized titanomagnetite depends on the direction between magnetic field and TRM during the oxidation process.

 

 

 
On the evolution equations of field gradient tensor invariants in MHD Theory
Authors: Quattrociocchi Virgilio , Consolini Giuseppe , Materassi Massimo , Alberti Tommaso , Pietropaolo Ermanno
Published: March 2022

The understanding of the evolution of turbulence in space plasmas requires the investigation of magnetic field and plasma structures and their time evolution. Indeed, the interactions among different topological multi scale structures have been shown to play an important role tu understand the energy transfer across scales and dissipation. A possible approach to this issue is the study of the geometrical invariants of magnetic and velocity field gradient tensors from a Lagrangian point of view. In the early 1980 a series of works (Vielliefosse, 1982 and 1984) discussed a nonlinear homogeneous evolution equation for the velocity gradient tensor in fluid dynamics.  Here, we derive the evolution equations of the geometrical invariants of the magnetic and velocity field gradient tensors in the case of magneto-hydrodynamic theory and discuss their application to the analysis of magneto-hydrodynamic turbulence in space plasmas.
Glacial fluctuations in the southwestern Wicklow Mountains, Ireland.
Authors: Jackson Margaret , Bromley Gordon , Hall Brenda
Published: March 2022

Mapping and dating former glacial margins is a key tool for assessing the sensitivity of glaciers to changing climate conditions, both past and future. However in many regions, such as along the northeastern margins of the North Atlantic, direct chronologic control on past glacier extent can be sparse. In particular, the former extent and elevation of the Irish Ice Sheet (IIS) during the Last Glacial Maximum (LGM; 26-19 ka) and subsequent termination remain a topic of debate - due in part to the coarse resolution of existing (direct) age control on glacial margins. This includes the margins of former valley and cirque glaciers that nucleated in the Irish highlands after local retreat of the IIS. In eastern Ireland, the Wicklow Mountains host numerous valley and cirque moraines that are largely undated, evidence of past glacial fluctuations following the LGM. Here we report new geomorphic mapping and cosmogenic beryllium-10 surface-exposure ages of moraines in the Glen of Imaal in the southwestern Wicklow Mountains. Our preliminary beryllium-10 ages provide new chronologic constraint on the extent of glaciers in the Glen of Imaal following the LGM. We also compare our preliminary glacial chronology with records of wider North Atlantic climate to investigate the response of ice in the Glen of Imaal to changing climate conditions. These data provide new insight on Ireland’s glacial past, and yield vital information on climate and glaciation in the wider North Atlantic region. 
Investigation of Monthly Emission Variations using TROPOMI SO2 Retrievals for Lignite-Fired Power Plants with Temporary Shutdowns
Authors: Deger Sumeyye Sena , Kaynak Burcak
Published: March 2022

The existing lignite reserves in Turkey are used for energy generation in coal-fired power plants (CPPs) and cause high amount of SO2 pollution due to low calorific value and high sulfur content. Therefore, large-capacity CPPs in Turkey are the most important sources of SO2 pollution. Shutdown and semi-shutdown periods were observed in the recent years for these CPPs with old technologies and insufficient treatment technologies. The daily electricity productions were also investigated and high variability, even in operating periods, were observed. Six major CPPs utilizing lignite were temporarily shut down on January 1, 2020 on the grounds that they did not have the necessary treatment system and exceeded the limit values, and reopened in June 2020 after requirements were partially or fully met. The impact of the temporary shutdowns for the aforementioned CPPs on SO2 emissions, and SO2 pollution using TROPOMI SO2 retrievals was investigated here. 2-year period (2019-2020) covering the shutdown and reopening periods was selected and the impacts on SO2 retrievals were examined. Although there are limited number of ground measurement stations in the region for the study period (2019-2020), ground-level SO2 concentrations were also used for comparison with retrievals and investigation of the impact of shutdown periods.   

To estimate monthly SO2 emissions from point sources using retrievals, a previously developed method by Fioletov et al. (2015) fitting SO2 retrievals to a three-dimensional (3-D) parameterization were used for processing SO2 columns and wind speed data. For emission estimations, TROPOMI Level-2 (L2) SO2 product was processed and low quality data were removed according to quality criteria. In order to reduce noise in the data, SO2 retrievals were averaged for 1×1 km2 gridded domains around CPPs using an oversampling method and monthly averages were estimated. Different oversampling distances were applied to obtain the clearest signal, and 10 km radius was selected indicating reduced noise but sufficient spatial variability. The 3-D parameterization method was applied to SO2 retrievals near the CPPs that were shut down. Since the uncertainty in the emission inventories can be quite high, these emission estimates using TROPOMI SO2 retrievals give us a chance to assess the available annual estimates such as EMEP. This method aims to obtain more realistic and accurate emissions by estimating monthly SO2 emissions for CPPs with shutdowns.
System identification of a high-rise building: a comparison between a single station measuring translations and rotations, and a traditional array approach.
Authors: Rossi Yara , Clinton John , Chatzi Eleni , Schmelzbach Cédric , Rothacher Markus
Published: March 2022

We demonstrate that the extended dynamic response of an engineered structure can be obtained from just a single measurement at one position if rotation is recorded in combination with translation. Such a single station approach could save significant time, effort and cost when compared with traditional structural characterization using arrays. In our contribution we will focus on the monitoring of a high-rise building by tracking its dynamic properties, e.g., natural frequencies, mode shapes and damping. We present the results of the system identification for the Prime Tower in Zurich – with a height of 126 m, this concrete frame structure is the third highest building in Switzerland. It has been continuously monitored by an accelerometer (EpiSensor) and a co-located rotational sensor (BlueSeis) located near the building center on the roof for the past year. The motion on the tower roof includes significant rotations as well as translation, which can be precisely captured by the monitoring station. More than 9 natural frequencies, including the first 3 fundamental modes, as well as the next two overtones, where translations are coupled with rotations, are observed between 0.3 – 10 Hz, a frequency band of key interest for earthquake excitation, making an investigation essential. Using temporary arrays of accelerometers located across the roof and along the length of the building to perform a traditional dynamic characterisation, we can compare the array solution with the new single location solution in terms of system identification for the Prime Tower.
Interhemispheric asymmetries, ITCZ location and interannual tropical Atlantic-Pacific interactions produced by South Atlantic cooling.
Authors: Losada Teresa , Rodríguez-Fonseca Belén , Mechoso C. Roberto , Mohino Elsa , Castaño-Tierno Antonio
Published: March 2022

Tropical interbasin teleconnections at inter-annual time scales are receiving much attention in the last years. However, their controlling factors and long-term changes are still under debate. In this work, we investigate whether selected features in the climatology, the position of the ITCZ and strong tropical convection, can influence the teleconnections between the tropical Atlantic and Pacific basins at inter-annual timescales.

For investigation, we contrast a CGCM control simulation with an experiment in which the climatological position of the ITCZ is shifted in latitude by artificially reducing the shortwave radiation incident in a region of the south Atlantic sector. The perturbation magnitude and sign are such that the local model’s biases in Atlantic SST are reduced. The experiment shows stronger interannual variability over the tropical Atlantic and Pacific oceans, a westward extension of the Atlantic Niño pattern, and enhanced interannual teleconnections between equatorial Atlantic and Pacific.

We examine the mechanisms at work for these changes. We find several factors as major contributors to enhance the tropical interbasin teleconnections. One is the modified Walker circulation resulting from the westward extension of SST anomalies during the Atlantic Niño and concurrent westward displacement of convection. The other factors are the enhancement of the precipitation at the equator and the shallowing of thermocline in the Pacific, which make the latter basin more sensitive to both local and remote perturbations.

On the contrary, the North Tropical Atlantic – equatorial Pacific teleconnection is weakened in the experiment, despite the strongest impact of the NTA anomalies in the north tropical Pacific winds. due to the opposite effect on divergence exerted by the off equatorial winds related to NTA and the equatorial winds related to the concomitant warming in the eastern and central equatorial Pacific.
Rail-based cosmic ray neutron sensing (CRNS): pushing the boundaries towards expanding footprints and temporal resolutions
Authors: Altdorff Daniel , Oswald Sascha , Zacharias Steffen , Zengerle Carmen , Mollenhauer Hannes , Dietrich Peter , Attinger Sabine , Schrön Martin
Published: March 2022

Cosmic ray neutron sensing (CRNS) has become an established method for deriving the soil water content (SWC), based on the inverse relationship of neutron counting and the SWC of the surrounding area. The provided footprint, lateral up to 200m and vertical of several decimeter, qualifies CRNS to bridge the information gap between classical hydrogeophysical approaches and remote sensing. While stationary CRNS offers continuous long-term SWC measurements at high temporal resolution, the covered area remains fixed and predefined. Car-borne CRNS roving on the other hand, allows to expand the mapped area. However, the method requires active operation and is limited to snap shot information only. As an alternative, the operation of a permanent mobile CRNS platform on trains promises to combine the advantages from stationary and car-borne CRNS measurements, as recently suggested by Schrön et al. (2021), while also its technical implementation, data processing and interpretation raises new challenges and complexity.

In this study we introduce a fully automatic CRNS railway system, installed in a conventional locomotive of a freight train, as first and novel of its kind. Results of the first phase of operation will be presented. The measurements along an experimental rail track were supported by local SWC measurements, gravimetric and dielectric records (Mobile Wireless Ad-hoc Sensor Network), at three areas along the railway, and by a newly installed weather station. Additionally, car-borne CRNS data were recorded on two days close to the railway track.

Preliminary results of data collected between September and December 2021 showed very stable spatial pattern in relation to the segments crossed by the train, which have been confirmed by the car-borne dataset. Temporal variations within hours were also evident as direct or indirect response to local rain and snow events.  Based on the first results, we are confident, that rail-based CRNS offers the chance to play a prominent role in addressing soil hydrology at landscape scale in the future.

Schrön, M., Oswald, S. E., Zacharias, S., Kasner, M., Dietrich, P., & Attinger, S. (2021). Neutrons on rails: Transregional monitoring of soil moisture and snow water equivalent. Geophysical Research Letters, 48, e2021GL093924

 
Assessment of angular distribution model of radiance: a comparison of the CIE model output with radiation transfer calculations.
Authors: Bham Sara , Saint-Drenan Yves-Marie , Gschwind Benoit , Blanc Philippe
Published: March 2022

The angular distribution of solar downwelling at Earth surface is of interest namely for emerging applications such as in building design and management (energy efficiency, visual and thermal comfort).

The operational service of CAMS Radiation, named McClear, is a webservice providing the three solar downwelling irradiance components global, diffuse, direct normal on the ground under clear sky conditions from CAMS data with good accuracy ((Lefèvre et al., 2013), (Gschwind et al., 2019)). In preparation to the extension of McClear capabilities, we consider the CIE modelling approach (Darula and Kittler, 2002) as a natural option because it is widely used in the literature. The CIE modelling approach consists in the product of two functions: (1) the scattering function that relates the relative radiance of a sky feature to its angular distance from the sun and (2) the gradation function that explains the variation of the radiance with the angular distance of a sky element to the zenith angle. The basic assumption behind this approach is that the distribution of the radiation in the sky vault can be decomposed in these two functions. As a preliminary to the extension of McClear service, we would like to test the validity of this assumption. For this purpose, we have selected the Perez model (Perez et al., 1993, 1990) that is based on the CIE approach and show good poerformances (Alshaibani et al., 2020; Darula and Kittler, 2002).

We compared the downwelling angular solar radiance at the surface of the Earth calculated by the Perez model and by the Radiative Transfer Model libRadtran a software package used for radiative transfer calculations such as the distribution of the spherical radiance and irradiance (Mayer and Kylling, 2005) also used as basis of McClear irradiance model. In this comparison, we consider several meteorological situations with different atmospheric composition in ozone, water vapor, aerosols loads, etc., but also with different Sun-Earth geometry and different bidirectional reflectance distribution function (BRDF) of the ground. This investigation was beneficial to evaluate the domain of validity of the CIE approach assumption. We described the methodology, discuss the results in view of the targeted application. and we provide some idea for an alternative to the CIE approach to extend McClear in a radiance model.

 

 

 

 

 
A methodology to understand the wind-driven circulation in semi-enclosed bays and its connectivity with the open sea at the southern coast of France
Authors: Caceres Euse Alejandro , Bourg Natacha , Molcard Anne
Published: March 2022

By applying an unsupervised neuronal network (NN) to sea velocity profiles and wind data, it was possible to determine the main wind-driven circulation patterns in the Toulon bay. In addition, the NN outputs were utilized to perform a conditional averaging to High-Frequency radar surface current data (HFR) and the atmospheric AROME model, in order to understand the connectivity between the inner Toulon bay circulation features and the offshore marine-atmospheric conditions. For instance, upwelling scenarios are observed under strong westerly winds, whereas the downwelling is present under easterly wind conditions. Additionally, a barotropic system is observed when weak-mid wind blows for long time periods, and first baroclinic modes occur under strong wind events. Up to date, few studies have presented a clear connectivity between semi-enclosed bays and the offshore conditions, particularly in the northwestern Mediterranean Sea. Thus, this methodology presents great advantages when trying to study the interaction between semi-enclosed bays and the open sea by means of a combination of several in situ meteo-marine information.
Simultaneous CO2 and 14CO2 atmospheric inversions over Europe to quantify fossil fuel CO2 emissions
Authors: Gómez-Ortiz Carlos , Monteil Guillaume , Karstens Ute , Basu Sourish , Hammer Samuel , Scholze Marko
Published: March 2022

The concentration of atmospheric carbon dioxide (CO2) has increased since the pre-industrial era (1750) due to human activity leading to a warming of the global land and ocean surface of 1.0 ± 0.2 ºC over the last 30 years could reach 1.5 ºC between 2030 and 2052. A better understanding of the fossil fuel CO2 emission sources is essential to develop strategies to reduce these emissions, and thus trying to stop the global warming produced by the accumulation of CO2 in the atmosphere. Policies to achieve these reductions require accurate and robust estimates of these emissions by a monitoring system based on independent atmospheric observations. This system must be able to separate the impact of anthropogenic CO2 emissions from the effect of the complex natural carbon cycle, which both affect atmospheric CO2 concentrations.

Radiocarbon (14CO2) measurements have been used in conjunction with total CO2 measurements on both local (e.g. Indianapolis and Heidelberg) and regional scales (e.g. North America and Europe) to separate fossil fuel CO2 fluxes from biogenic CO2. The estimation of fossil fuel emissions from atmospheric observations can, in principle, be done by inverse modeling. In this work we will use the LUMIA (Lund University Modular Inversion Algorithm) for performing a series of observation system simulation experiments (OSSEs) inverting simultaneously terrestrial CO2 and 14CO2 observations from the Integrated Carbon Observation System (ICOS) station network to solve for both the natural fluxes (mainly terrestrial) and the anthropogenic fossil fuel emissions, accounting also for the ocean and terrestrial 14C disequilibrium fluxes. The OSSEs will be performed on a spatial domain over Europe, with a spatial resolution of 0.1° for fossil fuel CO2 sources and 0.5° for natural CO2 fluxes and a weekly temporal resolution for natural and anthropogenic emissions and monthly for ocean and terrestrial disequilibrium fluxes 2009 to 2011. We will assess the suitability of the current ICOS 14CO2 observation network as well as potential extensions to estimate anthropogenic fossil fuel emissions.
Alfvén to kinetic Alfvén wave conversion in inhomogeneous heliospheric plasmas
Authors: Pucci Francesco , Bacchini Fabio , Malara Francesco , Lapenta Giovanni
Published: March 2022

We present a mechanism through which an Alfvén wave (AW) propagating in a magnetic shear is converted into kinetic Alfvén waves (KAWs), producing ion and electron heating [1]. It is well known that an AW propagating in a medium in which the Alfvén speed is inhomogeneous undergoes phase-mixing, which produces a variation of the AW phase in the direction perpendicular to the field along which the AW is propagating. When such a perpendicular scale of variation eventually becomes comparable to the ion Larmor scale, the AW is converted into KAWs in the region where the Aflvén speed is inhomogeneous [2]. Through fully kinetic Particle-in-Cell simulations, we show that this mechanism produces a differential heating of ions and electrons. Using a heuristic argument, we claim that such differential heating is justified because ions and electrons can access a different amount of the kinetic and magnetic energy transported by the AW. Our simulations also recover the electron Velocity Distribution Functions (VDF) that have been detected in the presence of KAW activity in previous observations of the Earth’s magnetospheric plasmas [3]. The mechanism we propose may explain the origin of those electron VDF features. Moreover, it may contribute to heating other heliospheric plasmas (e. g., the solar corona and the solar wind), where both Alfvén waves and magnetic shears are present. 

[1] F. Bacchini, F. Pucci, F. Malara, and G. Lapenta, Kinetic Heating by Alfvén Waves in Magnetic Shears, Phys. Rev. Lett. 128, 025101, 2022

[2] C. L. Vásconez, F. Pucci, F. Valentini, S. Servidio, W. H. Matthaeus,  & F. Malara, Kinetic Alfvén wave generation by large-scale phase mixing, The Astrophysical Journal, 815(1), 7, 2015

[3] D. J. Gershman, et al., Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave, Nature communications, 8(1), 1-10,  2017

 
Influence of radiation and temperature before and after the summer solstice on leaf senescence dates of European beech
Authors: Bucher Raymo , Palouš Daniel , Crowther Thomas , Zohner Constantin
Published: March 2022

Our understanding of ecosystem responses to climate change is hampered by a poor understanding of the environmental drivers of autumn leaf phenology in temperate and boreal forests. Specifically, the interplay between climate and day length in regulating autumn senescence is still poorly understood. In our recent experiment on European beech seedlings, we studied the effects of radiation (shading) and temperature throughout the vegetation season on autumn leaf senescence dates. We found that the effects of temperature and radiation differ before and after summer solstice, with pre-solstice cooling delaying leaf senescence dates by 10.2 ± 2.5 days and pre-solstice shading having little effect. By contrast, cooling after the summer solstice tended to advance leaf senescence, while post-solstice shading delayed senescence dates by 6.5 ± 2.8 days. These findings suggest a pre-solstice effect of temperature linked to growth (sink) processes of trees, whereas radiation appears to directly affect senescence through ageing effects on leaves. These findings can help to constrain uncertainties in the length of the vegetation season and annual carbon uptake, thereby helping to deepen knowledge on the interactions between climate and ecosystem dynamics.
Cross-correlations of a coupled ensemble hydrodynamic and water quality forecast 
Authors: de Korte Elias , El Serafy Ghada
Published: March 2022

Growing food, renewable energy demand and nature restoration have led to an increasing competition for space. European seas are considered as an opportunity for the joint use of aquaculture, renewable energy, but also to promote nature restoration. The concept of multi-use and co-location of marine activities was introduced to promote a sustainable use of European waters. Deltares is leading the Europe Horizon2020 funded UNITED project that aims to demonstrate pilots of multi-use, consequently identify synergies and bottlenecks. Offshore aquaculture greatly benefits from real-time operational forecasting capabilities since in-situ observations and frequent offshore expeditions are expensive. The Dutch Continental Shelf Model (DCSM) is a state-of-the-art hydrodynamic and water quality model developed by Deltares based on the Delft3D-FM software. This model has been validated for hydrodynamic and water quality applications on a wide spatial and temporal scale within the Dutch Continental Shelf. However, model bias is expected for the prediction of oyster and seaweed growth. Model bias can be region-specific and therefore we focus on one of the UNITED pilots, 50 km off the Belgian coast. Observations are often scarce but have proven to be effective for assimilation with water quality model applications in some cases. The aim of this research is to identify model bias and cross-correlation between the coupled ensemble modules to inform the implementation of an Ensemble Kalman Filter (EnKF) for the assimilation of observations.