bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the links between primary metabolites of medicinal species with leaf hyperspectral reflectance
Authors: Gupta Ayushi , Srivastava Prashant K , Shanker Karuna
Published: March 2022

Recent studies have shown that the turnover in tree species composition across edaphic and elevational gradients is strongly correlated with functional traits. However, our understanding of functional traits has been limited by the lack of detailed studies of foliar chemistry across habitats and the logistical & economic challenges associated with the analysis of plant functional traits at large geographical scales. Advances in remote sensing and spectroscopic approaches that measure spectrally detailed light reflectance and transmittance of plant foliage provides accurate predictions of several functional chemical traits. In this study, Pyracantha crenulata (D. Don) M. Roemer has been used, which is an evergreen thorny shrub species found in open slopes between 1,000 and 2,400 m above mean sea level. P. crenulata is used in the treatment of hepatic, cardiac, stomach, and skin disease. In this study the P. crenulata leaves samples spectra were recorded using an ASD spectroradiometer and following primary metabolites such as chlorophyll, anthocyanin, phenolic, and sterol were analyzed. The spectroradiometer data were preprocessed using filter and then reduced to a few sensitive bands by applying feature selection to the hyperspectral data. The band values were directly correlated with the measured values. The analysis indicates a significant correlation between P. crenulata primary metabolite in the Visible and Infrared region (VISIR). This result suggests that molecules that have important functional attributes could be identified by VISIR spectroscopy, which would save a lot of time and expense as compared to wet laboratory analysis.
Extreme wintertime surface energy budget anomalies in the high Arctic
Authors: Murto Sonja , Caballero Rodrigo , Svensson Gunilla , Papritz Lukas , Messori Gabriele , Wernli Heini
Published: March 2022

In recent decades the Arctic has warmed faster than the global mean, especially during winter. Wintertime Arctic warming has been attributed to various mechanisms, with recent studies highlighting the important role of enhanced downward infrared radiation associated with anomalous influx of warm, moist air from lower latitudes. Here we study wintertime surface energy budget (SEB) anomalies over Arctic sea ice on synoptic time scales, using ERA5 reanalysis data (1979-2020). With a new algorithm introduced here, we identify regions exhibiting large positive daily-mean SEB anomalies, and temporally connect them to form life-cycle events. Using Lagrangian tracers, we show that the majority of these winter events are associated with inflow from the Atlantic or Pacific Oceans, driven by the large-scale circulation. They show similar temporal evolution. The onset stage, located around the marginal ice zone, is characterized by roughly equal contributions of net longwave radiation and turbulent fluxes to the positive SEB anomaly. As the events evolve and move further into the Arctic, SEB anomalies decrease due to weakening sensible heat fluxes as the surface adapts. The magnitude of the surface temperature anomaly is determined by the downward longwave radiative flux and changes little over the life-cycle. As this study highlights the importance of turbulent fluxes in driving SEB anomalies and downward longwave radiation in determining local surface warming, both components need to be properly represented by climate models in order to properly model the Arctic climate.
Equatorial electron pitch angle distributions in Earth's outer radiation belt: Storm-time evolution and empirical modeling
Authors: Smirnov Artem , Shprits Yuri , Allison Hayley , Aseev Nikita , Drozdov Alexander , Kollmann Peter , Wang Dedong , Saikin Anthony
Published: March 2022

Pitch angle distributions (PADs) of trapped particles play an important role in understanding the processes driving the dynamics of Earth’s radiation belts and ring current. The Van Allen Probes mission has provided electron observations of PADs with an unprecedented coverage in energy (from tens of keV to several MeV) and pitch angles during the mission’s lifespan. We approximate the equatorial electron PADs using the Fourier sine series expansion up to degree 5. The corresponding coefficients can be directly related to the main PAD shapes (pancake, butterfly, flat-top and cap), and the approximated PADs can be easily integrated and converted to omnidirectional flux. Using the entire Van Allen Probes MagEIS data set in 2012-2019, we analyze the response of the equatorial electron PAD shapes to 129 geomagnetic storms with minimum Dst< -50nT. At lower energies (<100 keV), the PADs are stable throughout geomagnetic storms and mainly exhibit a pancake shape. At higher energies, the storm-time PAD evolution depends on the magnetic local time (MLT). At dayside, the pancake distributions become steeper during the main phase and then recover to their original broader form during recovery phase, likely due to the inward radial diffusion. At nightside MLT, the butterfly distributions become more pronounced during the main phase due to the combination of drift-shell splitting and magnetopause shadowing. We present a simple polynomial regression model of PAD shapes driven by the solar wind dynamic pressure. The model allows reconstructions of the full equatorial PADs based on uni-directional measurements at low equatorial pitch angles (applicable to LEO satellite data), as well as from omnidirectional electron flux observations and significantly outperforms the standard sin(alpha) approximation.
Hafnium-neodymium isotope evidence for enhanced weathering and tectonic-climate interactions during the Late Cretaceous
Authors: Corentin Pauline , Pucéat Emmanuelle , Pellenard Pierre , Guiraud Michel , Blondet Justine , Freslon Nicolas , Bayon Germain , Adatte Thierry
Published: March 2022

Over million-year timescale the carbon cycle evolution is driven by mantle CO2 degassing (source) and by continental weathering that drawdowns atmospheric CO2 through silicate weathering reactions (sink). Based on a novel geochemical proxy of chemical weathering intensity (i.e. using measurements of Hf and Nd isotope ratios in clay-size fractions of sediments) and clay mineralogy, we discuss the links between tectonic, continental weathering and climate evolution during the late Cretaceous. That period records the very first step of the last greenhouse to icehouse transition and is concomitant to major uplift phases affecting the African and South-American margins.

Two sites along the South American Atlantic margin (ODP 356 and 1259) were targeted based on their relatively complete record of upper Cretaceous sediments. At Site 356, our results indicate the occurrence of enhanced chemical weathering during the Campanian and Maastrichtian following the uplift of the Southeastern Brazilian margin that promoted the establishment of more hydrolysing conditions.

At Demerara Rise (Site 1259), our data suggest a coupling between physical erosion and chemical weathering, which may be explained in this area by the presence of persistent hydrolysing conditions typical of equatorial climate and reduced tectonic activity. From the Turonian to the early Campanian, i.e. a period of relative tectonic quiescence, our data suggest that climate was likely the main driver controlling the evolution of chemical weathering intensity. By contrast, from the middle Campanian to Maastrichtian, we propose that mountain uplift, although moderate, induced a marked increase in chemical weathering intensity.

Together, this new data acquired at two 2 sites that encountered different regional climatic, geologic and tectonic conditions suggest that chemical weathering markedly intensified during the late Cretaceous and likely acted as a major sink for atmospheric CO2. While the onset of weathering increase at both sites appear to postdate the initiation of global temperature decrease, we suggest here that this process could have participated to accelerating or maintaining colder climate conditions at that time.

 

Key Words: late Cretaceous – paleoclimate – weathering – uplift - clay mineralogy – Hf-Nd isotope
Grid resolution dependency of land surface heterogeneity effects on boundary-layer structure
Authors: Poll Stefan , Shrestha Prabhakar , Simmer Clemens
Published: March 2022

Land surface heterogeneity exerts a substantial impact on atmospheric boundary-layer (ABL) evolution by spatially varying the distribution and partitioning of surface energy fluxes and triggering secondary circulations. The representation of this physical process in numerical weather prediction (NWP) models is especially affected in the terra incognita as the model grid resolution approaches the length-scale of the largest eddies in the boundary layer. We explore these effects for a mesoscale strip-like land surface inhomogeneity in land cover, soil moisture or a superposition of both embedded in an elsewhere homogeneous landscape. The study is conducted with the numerical weather prediction model ICON (ICOsahedral Nonhydrostatic), using the default operational level 2.5 Mellor–Yamada turbulence closure (MY) and a large-eddy simulation (LES) configuration as a benchmark. While simulations with the default ABL scheme approach the LES reference when refining the spatial grid towards finer resolution, the model generates artificial circulations leading to ABL height oscillations when the horizontal grid resolution (∆x) approaches the ABL height (zi). The effect of these model-induced circulations on the state of the boundary layer is even present with weak thermal heterogeneity (∆H) under low background wind speed (vx) but diminishes with increasing background wind speed. The tuning of the asymptotic turbulent mixing length-scale (𝑙∞) in the operational ABL scheme helps in reducing the amplitude of the oscillations, thereby reducing the artificially induced circulations due to thermal heterogeneity which might act as unintentional trigger for clouds and precipitation. Based on the tuned synthetic model data from sensitivity runs, we propose a new parametrization for a 2-D 𝑙∞ as a function of ∆H, zi/∆x and vx, which is otherwise held as a constant in the ABL scheme.
Up- and Downscaling of Carbon dioxide (CO2) concentrations in an Urban Environment
Authors: Retière Alain , van den Dool H. Gijs
Published: March 2022

Understanding how carbon dioxide behaves in an urban environment is one of the requirements of setting Carbon Credits and avoiding double counting. There are several different data sources, and techniques, available to capture the CO2 concentration, and in our study, we are looking at the combination of two completely different data streams: remotely sensed CO2, through the NASA OCO2/3 satellite mission (complemented with national flux-tower reading), and a local IoT network of CO2 gound sensors.
Independently used, it is possible to indicate the CO2 concentration in a region with either data stream. E.g., it is possible to downscale the Remote Sensed (RS) data to a more granular level, but this will only be possible over the area where there are measurements because of the lack of ground-truthing points. The reverse is applicable for the IoT area, here it is possible to upscale the data, but the field of vision of the IoT is limited to the sites for which it is deployed.
This study aims to develop a model that combines the two techniques by integrating the high-resolution land cover information, in this case, the Copernicus Urban Atlas, to fill in the OCO2/3 data gaps with the measurements of the ground sensors.
To test this hypothesis that it is possible to both up- and downscale CO2 concentrations, a network of ground sensors will monitor the CO2 concentrations in a middle-sized town in France (Dijon), and we deployed the first set of 4 sensors on strategic land cover areas to establish the first baselines. By researching the relationships between CO2 concentrations and land cover, we hope to create an enhanced CO2 index that captures the local characteristics and gives better insights into the regional spatial-temporal dispersion patterns of CO2 concentrations and extrapolate the findings to regions where only either RS or IoT data is available.
Stress coupling between supraglacial lakes during rapid drainage
Authors: Stevens Laura A. , Das Sarah B. , Behn Mark D. , Lai Ching-Yao , Joughin Ian , Kingslake Meredith , Kingslake Jonathan
Published: March 2022

Greenland supraglacial lakes sometimes drain to the ice-sheet base only hours to days apart in time, leading to the hypothesis that stress transmission following one drainage may be sufficient to induce hydro-fracture-driven drainages of other lakes. However, available observations characterizing the time- and length-scales of drainage-induced stress perturbations are insufficient to evaluate this hypothesis, hindering our understanding of whether lower-elevation lake drainages could generate stress changes that initiate hydro-fracture beneath lakes in inland ice-sheet regions. Here, we invert ice-sheet surface displacement observations from a dense Global Positioning System (GPS) array deployed around three supraglacial lakes in the Greenland Ice Sheet ablation zone to estimate the space-time history of slip and opening along pre-defined planes within an elastic half-space that best reproduces GPS observations during two rapid drainage events. We then use these slip and opening estimates to forward model ice-sheet surface stresses across all three neighboring lake basins and investigate stress transmission between the basins. We find that drainage of a central lake places neighboring basins in either tensional or compressional surface stress relative to their individual hydro-fracture scarp orientations, which, respectively, promotes or inhibits hydro-fracture initiation beneath those lakes. Surface-stress-change direction is asymmetric across the lake-draining fracture of the central lake and highly dependent on where surface uplift occurs. On elastic timescales, lake-drainage-induced stresses within the extent of the GPS array in the inland direction remain low within ~3 km of the central lake. This short length-scale for stress coupling in the inland direction is consistent with idealized lake-drainage scenarios for different lake volumes and ice-sheet thicknesses. Our observations and idealized-model results support the stress-transmission hypothesis for inducing hydro-fracture-driven drainage of lakes located within the region of uplift produced by the initial drainage, but refute this hypothesis for distal lakes not located down the subglacial hydraulic catchment from the initial drainage.
Source Parameter Determination Using a Spectral Decomposition Approach in the central-southern Europe
Authors: Yen Ming-Hsuan , Bindi Dino , Zaccarelli Riccardo , Oth Adrien , Edwards Benjamin , Cotton Fabrice
Published: March 2022

A spectral decomposition of the Fourier amplitude spectra is applied to determine the source parameters of earthquakes (source spectral shape, stress drop) that have occurred in central-southern Europe. About 52 million waveforms recorded in the target area since the late ‘90s have been downloaded from the European Integrated Data Archive (EIDA) within the tool stream2segment (Zaccarelli et al., 2019), by using the event catalog of the International Seismic Centre (ISC) and innovative data quality assessment. A non-parametric decomposition approach in this study introduced a regionalization for the attenuation models into two spatial domains (southern and “active” Europe, northern and “stable” Europe). For each domain, a spectral attenuation with hypocentral distance model is simultaneously determined and used to remove regional specific propagation effects from the spectra of recordings. Once isolated from local site effects, the obtained source spectra of 4380 earthquakes of magnitude larger than 2.5 are fitted to a standard -model to determine the seismic moment, corner frequency and Brune stress drop. The scaling relationship, spatial variation and variability of these source parameters are finally derived and discussed.
Feedback of tropical cyclones on El Niño diversity
Authors: Wang Qiuyun , Li Jianping
Published: March 2022

Understanding of the El Niño phenomenon is improving and several studies have considered the dynamics of El Niño diversity, however, the important role of tropical cyclones has not been reported. Here we show a clear influence of tropical cyclones over the western North Pacific on the spatial pattern of El Niño: By changing the Walker circulation and equatorial thermocline, strong (weak) accumulated cyclone energy helps to shift the center of strongest sea surface temperature anomalies three months later to the equatorial eastern (central) Pacific. The greater number of central-Pacific El Niño events after 1999/2000 may be associated with weaker accumulated cyclone energy in this period. A modified physically based empirical model (ACE+SST model) for predicting El Niño spatial patterns is constructed that captures well the spatiotemporal characteristics of El Niño events. Taking into account the key influence of western North Pacific tropical cyclones on El Niño diversity will improve our understanding and prediction of El Niño.
A large-scale study of the carbon stock of Hungarian forest soils
Authors: Bidló András , Végh Péter , Horváth Adrienn
Published: March 2022

Temperate forest ecosystems store significant amounts of organic carbon. Site conditions, species composition, and age of stands largely influenced the amount of stored carbon. International and Hungarian studies have shown that nearly half of the carbon stored in the soil in organic matter forms in forest ecosystems. The main goal was to determine the amount of carbon stored in loess soil. Our preliminary studies have shown that climatic conditions (and the forest composition determined) have a huge effect on the carbon stock of soils. To demonstrate this effect, forest stands on loess bedrock under different climatic conditions were selected for the study. Soil drilling was performed in 40 stands and soil samples were taken by 10 cm layers from 0-110 cm depth. In addition to the soil samples, we also determined the litter mass and composition of the forest stand.
Results showed that the loess soil was leached under the forest stands, so its pH was 5.8 on average (min: 3.9; max.: 8.5). Only deeper levels contained 13% CaCO3 (min: 1.1%; max.: 37%) in the profiles. The texture of the soils was loam or clayey loam with good water holding capacity; therefore, the soil types were Luvisol and Cambisol soils. The average amount of carbon stored in the soils was 1.04 % (min.: 0.02%; max.: 7.3%)  In the future, we will try to clarify the relationship between soil organic carbon stocks and weather conditions.

Project no. 141603 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the MEC_R_21 funding scheme.
A consistent full waveform inversion scheme for imaging heterogeneous isotropic elastic media
Authors: Kan Li-Yu , Chevrot Sébastien , Monteiller Vadim
Published: March 2022

Multi-parameter teleseismic full-waveform inversion (FWI) can provide key insights on the composition and thermal state of the lithosphere. In the isotropic version of such inversions, one classically inverts for a set of independent model parameters,  for example (density, Vp, Vs). In this study, we demonstrate that by introducing model covariance matrices with non-diagonal terms to FWI, i.e. accounting for the existing correlations between density, Vp, and Vs, has a dramatic impact on the quality of the reconstructed models. We perform synthetic tests using with a simple subduction model. The teleseismic and regional wavefields are computed with our FK-SEM hybrid method. We invert vertical and radial component P waveforms from four teleseismic events coming from different epicentral distances and azimuths. We use a hierarchical iterative l-BFGS inversion, starting at long period (T > 10 s) to obtain a long wavelength model, and then progressively decreasing the spatial smoothing and cut-off period to 5 s and then 2.5 s. We also demonstrate that a complete non-diagonal model covariance matrix allows us to make the inversion results consistent, i.e. independent of the model parameterization. The inversions which account for the correlations between model parameters provide better models especially for density and Vs, less numerical artifacts, and are characterized by a faster convergence rate compared to inversions performed by assuming that model parameters are independent.
Zhidoy Alkali-Ultramafic Rock and Carbonatite Massif: GeochemicalFeatures, Its Sources And Ore-Bearing
Authors: Sotnikova Irina , Vladykin Nikolai , Alymova Natalia
Published: March 2022

The article considers the geological position of the Zhidoy massif and its age. The scheme of magmatism of the massif has been developed. The graphs of paired correlations of petrogenic elements in massif rocks which had a consistent trend in composition are given for validation purposes. The present article provides graphs of REE spectra and the spider diagram of rare elements concentration in the massif rocks. Pyroxenites are the early rocks of the massif, which are the ores for titanium. Titanium is concentrated in three minerals: titanium magnetite, ilmenite and perovskite. The main type of titanium ores, perovskite, is known only in the Zhidoy massif. A conclusion about the mantle sources of the primary magma of the massif
is drawn based on the geochemistry of the isotopes Sr and Nd.

Fig. 1 Spectra of rare-earth elements in rocks of the Zhidoy massif (chondrite-normalized).
Symbols: 1−pyroxenite, 2−ijolite, 3−syenite, 4−phenite

 

<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.4beb5309abe169714382461/sdaolpUECMynit/22UGE&app=m&a=0&c=9926448c5388c95eb7015a61871fa0ab&ct=x&pn=gepj.elif&d=1" alt="" width="627" height="675">

Fig. 2 Spider-diagram of the Zhidoy massif rocks

Conclusions
1. Three varieties of ore pyroxenites have been defined−titanium-magnetite, ilmenite and perovskite ore.
2. The petrochemical diagrams show a common trend in the composition of rock- forming elements, indicating the homomorphism of the rocks and their crystallization from a single primary magma.
3. Geochemical data also confirm the genetic relation of the Zhidoy massif.
4. Mantle source, the depurated mantle for the primary magma of the Zhidoy massif, has been determined on the basis of isotope data.
The new IAGOS Data Portal
Authors: Boulanger Damien , Bouhouili Asmae , Bex-Chauvet Olivier , Wolff Pawel , Thouret Valérie , Clark Hannah
Published: March 2022

IAGOS (In-service Aircraft for a Global Observing System) is a European Research Infrastructure that aims to provide long-term, regular and spatially resolved in situ observations of the atmospheric composition.  IAGOS observation systems are deployed on a fleet of commercial aircraft and perform uninterrupted measurements, from take-off to landing, of aerosols, cloud particles, greenhouse gases, ozone, carbon monoxide, water vapor and nitrogen oxides, from the surface to the lower stratosphere. The IAGOS database is an essential part of the global atmospheric monitoring network.

The IAGOS Data Portal (via https://www.iagos.org) is managed by AERIS, the French Data and Services Cluster for Atmosphere (https://en.aeris-data.fr). The new portal offers improved discovery and access to all the IAGOS datasets from the observational data to the derived and elaborated data products. Thanks to the H2020 project ENVRI-FAIR, all data is now managed in accordance with the FAIR principles. Rich metadata and data files are available in standardized formats (NetCDF-CF, etc.). The portal also provides advanced web-processing services such as visualisation capabilities and machine actionable access.

Particular attention has been paid to the interoperability of IAGOS data with external data portals. Interoperability is currently being implemented with other airborne programs such as SAFIRE and EUFAR, with other Research Infrastructures from the Atmospheric domain and more generally from the Environmental domain in the frame of the ENVRI community.

In the frame of the European projects ATMO-ACCESS and RI-URBANS, IAGOS is currently developing new advanced services such as: statistical analysis tools, combination of products from different sources with satellite data and models, Jupyter notebooks for demonstration of IAGOS data usage, footprints calculation and homeless data service for datasets acquired on mobile platforms.
Stochastic Chaos in Laboratory Earthquakes
Authors: Gualandi Adriano , Faranda Davide , Marone Chris , Mengaldo Gianmarco
Published: March 2022

Earthquakes are a complex natural phenomenon. They typically are the result of frictional instabilities along preexisting weakness zones called faults. The strain slowly builds up in the fragile Earth crust because of the presence of an external loading counterbalanced by friction forces at the faults’ interface. When the load cannot be balanced by the friction any further, the fault slips releasing the accumulated strain. Friction is a nonlinear phenomenon, and as such frictionally controlled systems may be subject to chaotic behavior. Seismic cycle analogs can be reproduced with rock friction experiments in the laboratory with a double direct shear apparatus. We show that laboratory earthquakes follow a low-dimensional random attractor. We explain the observations with a model of stochastic differential equations based on the rate- and state-friction framework. We show that small perturbations (less than 1‰) on the shear and normal stress can induce laboratory earthquakes aperiodic behavior with coefficient of variations of the order of some percent. The nonlinear nature of friction amplifies small scale perturbations, making mid-long term predictions of the system possible only statistically even for stick-slip events in a well controlled environment like the laboratory.
The vertical movement of Karpathos: Competing hypotheses  
Authors: veliz borel Violeta , Oncken Onno , Mouslopoulou Vasiliki , Begg John , Glodny Johannes
Published: March 2022

Karpathos is a roughly north-south oriented island that emerges between Crete and Rhodes in the forearc of the eastern Hellenic subduction system. It extends for ~60 km to the north of the 40 km contour of the plate interface depth. Further, the northern part of the island is confined to a N-S trending Horst bounded by two large normal faults that shape the seafloor off both, the eastern and western shore.  Furthermore, many normal faults, mainly in the north, strike parallel to the Horst and shape the topography onshore. Given the location and the structural configuration of the island, we expect that multiple processes are reflected in both the sedimentary and morphological record of vertical movement. Marine terraces and paleo-cliffs are observed all around the island recording its vertical movements over the last ~1 Ma. Moreover, sedimentary basins in the southern and central parts of the island are excellent archives of long-term uplift interrupted by subsidence over the last ~4.5 Ma. Twenty-five samples were collected at elevations between 1 and ~310 masl. We have gathered six (n=6) age/elevation data-points obtained by Sr-isotope dating, and nineteen (n=19) age/elevation data-points by radiocarbon dating. We explored the likelihood of different hypotheses on what drives the uplift:  whether it is driven by upper-crust normal faults, megathrust earthquakes, underplating, or a combination of these phenomena. We present preliminary results on both the temporal and spatial fluctuations of the vertical movement of Karpathos.
The internal structure of Venus and its global deformation
Authors: Saliby Christelle , Briaud Arthur , Fienga Agnes , Memin Anthony , Spada Giorgio , Melini Daniele
Published: March 2022

The Sun exerts tidal forces that deform the planet Venus, from deformation and mass redistribution in its interior, involving variation in the gravity field. The deformation of the planet induced by tidal forcing can be observed with the periodic variations of its gravity field and the Love number k2. The planet’s deformation is linked to its internal structure, most effectively to its density, rigidity and viscosity.  Hence the tidal Love number k2 can be theoretically estimated  for different planetary models.

The terrestrial planet Venus is reminiscent of the Earth twin planet in size and density, which leads to the assumption that the Earth and Venus have similar internal structures. In this work, the calculation of k2 is done with ALMA, a Fortran 90 program from Spada [2008] which computes the tidal and load Love numbers using the Post-Widder Laplace inversion formula. With a reference Venus model from Dumoulin et al. [2017], we investigate different parameters of the planet’s layers to calculate its frequency dependent tidal k2. We apply a random variation of each layer’s parameters within certain boundaries, which allows a statistical analysis of the possible Venus models that fall into the observed data (Mass, Moment of Inertia and k2). We test the effect of different parameters in the Venus model on the k2 and better understand the different hypotheses for the interior of Venus, as mantle viscosity to core structure (a fluid, solid and part fluid part solid core) .
The emergence of compound event analysis as a new research frontier
Authors: Zscheischler Jakob
Published: March 2022

Over recent years, research on compound weather and climate event has emerged as a new research frontier at the interface of climate science, climate impact research, engineering and statistics. Compound weather and climate events refer to the combination of multiple drivers and/or hazards that contribute to environmental or societal risk. Compound event analysis combines traditional research on climate extremes with impact-focused bottom-up assessments, thereby providing new insights on present-day and future climate risk. In this talk, I will illustrate my own trajectory into compound event analysis and highlight current and future challenges in this novel and exciting field of research. 
Evidence-based requirements for perceptualising intercatchment groundwater flow in hydrological models
Authors: Oldham Louisa , Freer Jim , Coxon Gemma , Jackson Christopher , Bloomfield John , Howden Nicholas
Published: March 2022

Groundwater-dominated catchments are often critical for nationally-important water resources. Many conceptual rainfall-runoff models used for the simulation of river flows tend to degrade in their model performance in groundwater-dominated catchments as they are rarely designed to simulate spatial groundwater behaviours or interactions with surface waters. Intercatchment groundwater flow is one such neglected variable. Efforts have been made to incorporate this process into existing models, but there is a need for greater emphasis on improving our perceptual models of groundwater-surface water interactions prior to any model edits.

In this study, national meteorological, hydrological, hydrogeological, geological and artificial influence (characterising abstractions and return flows) datasets are used to develop a perceptual model of intercatchment groundwater flow and how it varies spatially and temporally across the River Thames. We characterise the water balance, presence of gaining/losing river reaches and intra-annual dynamics in 80 subcatchments of the River Thames in the UK, taking advantage of its wealth of data, densely gauged river network and geological variability.

We show the prevalence of non-conservative river reaches across the study area, with heterogeneity both between, and within, geological units giving rise to a complex distribution of recharge and discharge points along the river network. We identify where non-conservative reaches can be attributed to intercatchment groundwater flow, and where other processes (e.g. human abstractions and discharge uncertainty) are likely the cause. Escarpments of Chalk and Jurassic Limestone show evidence of intercatchment groundwater flow both from headwater to downstream reaches, and out-of-catchment via springlines. We found temporal as well as spatial variability across the study area, with more seasonality and variability in river catchments on Jurassic Limestone outcrops and less on Chalk and Lower Greensand outcrops. Our results show the need for a degree of local investigation and hydrogeological perceptualisation within regional analysis, which we show to be achievable given relatively simple geological interpretation and data requirements.  We then discuss the inclusion of external flow fluxes within existing models to enable calibration improvements in groundwater-dominated catchments, and, importantly, the characterisation of these fluxes given the temporal and spatial variability of intercatchment groundwater flow that our perceptual model has shown.
The role of innovative econometric models in short-term hydropower optimization
Authors: Avesani Diego , Zanfei Ariele , Nicola Di Marco , Galletti Andrea , Francesco Ravazzolo , Maurizio Righetti , Majone Bruno
Published: March 2022

The recent transformation of the electricity market has modified the hydropower production paradigm, especially for storage reservoir systems. In particular, the process of market liberation has led to a shift in hydropower management approaches. These have moved from strategies oriented to maximizing energy production to strategies aimed at revenue maximization. Indeed, hydropower producers bid their energy production scheduling in advance, attempting to align the operational plan for the ensuing day (i.e., allocating 1-day ahead the hourly time series of turbined water discharges) with hours where the expected electricity prices are higher. As a result, the accuracy of 1-day ahead electricity prices forecasts, as given by econometric models, has started to play a key role in the short-term optimization of storage reservoir systems. Though recognized, this aspect has so far received limited attention in the literature.

This work aims to contribute to the topic by presenting a comparative assessment of revenues provided by the solution of short-term hydropower optimization problems driven by two econometric models during an entire year of simulation. Both models are autoregressive time-adapting hourly forecasting models which exploit the information provided by past values of electricity prices. One model, referred as Autoarimax, can be considered as the state-of-the-art in electricity prices forecasting, the peculiarities of which are rooted in the use of time-varying exogenous variables related to electricity demand and production, while the other, referred to as the Benchmark, can be considered a standard autoregressive model.

The added value of using an innovative econometric model is exemplified in two selected hydropower systems with different storage capacities located in the south- eastern Alpine region. The enhanced accuracy of electricity prices forecasting is not constant across the year due to the large uncertainties characterizing the electricity market, the fluctuations of which are controlled by short-term and seasonal imbalances in factors affecting electricity demand and production. Our results also show that the adoption of this more accurate econometric model leads to larger revenues with respect to the use of a standard model. The increased revenues depend strongly on the hydropower system characteristics, such as reservoir capacity and the ratio between inflows and maximum turbined water discharge that can be conveyed to the plant. Specifically, we showed that, for the reservoir characterized by a larger storage capacity, the use of Autoarimax forecasts led to a revenue increase of up to 2.31% at monthly scale with respect to the case in which Benchmark forecasts are used in the optimizations. This revenue gain can reach up to a 31.06% increase if we consider the maximum daily deviations.
Global climatic controls on the hydrological and thermal trade-offs of urban greening
Authors: Cuthbert Mark , Rau Gabriel , Ekstrom Marie , O'Carroll Denis , Bates Adam
Published: March 2022

Heat-related mortality and flooding are pressing challenges for the >4 billion urban population worldwide, exacerbated by increasing urbanization and climate change. Urban greening, such as green roofs and parks, can potentially help address both problems, but the geographical variation of the relative hydrological and thermal performance benefits of such interventions are unknown. Here we quantify globally how climate driven trade-offs exist between modelled hydrological retention and cooling potential of urban greening. Water retention generally increases with aridity in water limited environments, while cooling potential favors lower aridity, energy limited, climates. Urban greening cannot yield high performance simultaneously for addressing both urban heat-island and urban flooding problems in most cities globally. However, in more arid locations, where sustainable, irrigation might be used to improve potential cooling benefits while maintaining retention performance. We demonstrate that as precipitation becomes increasingly variable with climate change, the hydrological and thermal performance of thinner substrates would both diminish more quickly compared to thicker and more deeply vegetated systems, presenting challenges for urban greening strategies. Our results provide a conceptual framework and geographically targeted quantitative guide for urban development, renewal and policymaking.

(See further details in the forthcoming paper Cuthbert et al. (In Press) in the journal Nature Communications, which is a more developed version of the pre-print available here: https://eartharxiv.org/repository/view/2100/)
ABL determination by Raman lidar with different approaches in the frame of HyMeX SOP1
Authors: Summa Donato , Di Girolamo Paolo , Vivone Gemine , Franco Noemi , Giuseppe D'amico , De Rosa Benedetto
Published: March 2022

The atmospheric planetary boundary layer (ABL) represents the lower region of the atmosphere directly in contact with the earth's surface and strongly influenced by this surface. In this layer physical quantities such as flow velocity, temperature and humidity exhibit rapid fluctuations associated with turbulent motion and vertical mixing.

Characterization of the planetary boundary layer is of primary importance in a variety of fields such as weather forecasting, climate change modeling and air quality forecasting and therefore it is very important to determine it correctly. The structure of ABL can be complex and highly variable.  In this work different techniques to estimate the ABL height are compared. A first technique makes use of the pure rotational Raman lidar signals, which are strongly dependent on temperature. A second technique makes use of the  water vapor roto-vibrational Raman lidar signals in the lower troposphere. Further techniques based on the Morphological Image Processing Approach (MIPA) are also considered. In the present research work, we consider the measurements from the University of Basilicata Raman lidar system BASIL collected in the period 16-21 October 2012 in the frame of HyMex SOP1 [1,2,3].

References:

[1] Di Girolamo, P., R. Marchese, D. N. Whiteman, B. B. Demoz, Rotational Raman Lidar measurements of atmospheric temperature in the UV. Geophysical Research Letters, 31, L01106, ISSN: 0094-8276, doi: 10.1029/2003GL018342, 2004.

[2] Vivone, G., D'Amico G., Summa D., Lolli S., Amodeo A., Bortoli D., and Pappalardo G.. Atmospheric boundary layer height estimation from aerosol lidar: a new approach based on morphological image processing techniques Atmos. Chem. Phys., 21, 4249–4265, 2021 https://doi.org/10.5194/acp-21-4249-2021.

[3] Summa, D., P. Di Girolamo, D. Stelitano, and M. Cacciani, Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches, Atmos. Meas. Tech., 6, 3515–3525, 2013, www.atmos-meas-tech.net/6/3515/2013/doi:10.5194/amt-6-3515-2013
A Bayesian Belief Network model assessing the multi-scale effects of riparian vegetation on stream invertebrates
Authors: Forio Marie Anne Eurie , Burdon Francis J. , Witing Felix , Risnoveanu Geta , Kupilas Benjamin , Friberg Nikolai , Volk Martin , Mckie Brendan , Goethals Peter
Published: March 2022

Despite the benefits of riparian vegetation, they are limitedly implemented in water management – which is partly due to the lack of information on their effectiveness. In this context, social learning is valuable to inform stakeholders of the efficacy of riparian vegetation in mitigating stream degradation. Tools used in social learning activities are of paramount importance in the learning process. We developed a Bayesian belief network (BBN) model as a learning tool to simulate and assess the reach- and segment-scale effects of riparian vegetation properties and subcatchment-scale land use on instream invertebrates. We surveyed reach-scale riparian conditions, extracted segment-scale riparian and land use information from geographic information system (GIS) data and collected macroinvertebrate samples from four catchments in Europe (Belgium, Norway, Romania and Sweden). We modelled the ecological water quality, expressed as Average Score Per Taxon, as a function of different riparian variables using the BBN modelling approach. The collected data were used to populate the conditional probability table of the BBN model. The model simulations provided insights into the usefulness of both reach- and segment-scale riparian vegetation attributes in enhancing ecological water quality. We assessed the strengths and limitations of the BBN model for application as a learning tool. Despite some weaknesses, the BBN model has great potential in workshop activities to stimulate key learning processes that help inform the management of riparian zones.
Numerical weather prediction model outputs define intensity-duration thresholds of extreme-precipitation-induced sediment disasters
Authors: Siva Subramanian Srikrishnan , Srivastava Piyush , Sen Sumit
Published: March 2022

Rainfall intensity-duration (ID) thresholds are helpful to estimate the likelihood of natural hazards during extreme precipitation events. Sub-daily time-series of weather data is necessary to define precise ID thresholds of sediment disasters. The Himalayas, vulnerable to extreme precipitation events, experience large-scale sediment disasters, i.e., landslides, debris flows, and flash floods. Present early warning systems currently in operation encounter difficulties forecasting sub-daily time-series of weather due to instrumental and operational challenges. Here, we present a new framework to analyse and predict extreme rainfall-induced landslides using a weather research and forecasting model (WRF) followed by a spatially distributed numerical model. The operational framework starts with the WRF model running at 1.8 km × 1.8 km resolution. Then, the spatiotemporal numerical model for landslide forecasting at the same resolution uses the WRF model outputs. We calibrate the models using Uttarakhand, India's 2013 heavy rainfall-induced landslide events. We perform parametric numerical simulations to identify critical ID thresholds of landslides under different precipitation intensities, i.e., moderate rain, rather heavy, heavy rain, very heavy rain, and extremely heavy rain according to the India Meteorological Department (IMD) glossary. Our analysis opens avenues for integrating the WRF model with rainfall ID threshold-based territorial early warning of landslides. 
Remote-sensing of aerosol atmospheric rivers over the southwest Indian Ocean in September 2017: origins, evolution and impacts
Authors: Baron Alexandre , Duflot Valentin , Chazette Patrick , Gaetani Marco , Flamant Cyrille , Cuesta Juan , Payen Guillaume , Keckhut Philippe , Goloub Philippe
Published: March 2022

In the southern hemisphere, the dry season from June to October coincides with the occurrence of significant fires especially located along the tropical belt in Africa and South America. This fire activity is an important source of aerosols in the tropical troposphere and results in smoke plumes transported across long distances toward area generally aerosol-free. The atmospheric composition over the Indian Ocean is often influenced by biomass burning plumes shaped by the synoptic atmospheric circulation with high pressure over southern Africa and the movement of westerly waves that may embedded cut-off lows. The propagation over the Indian Ocean is then dependent on the position of the Mascarene High. The meandering shape of the plumes is then associated with an aerosol atmospheric river (AAR). Such a phenomenon has been sampled by spaceborne lidars and spectro-radiometers, and even observed above La Réunion (21.1°S, 55.3°E) during September 2017 by a ground-based lidar and a sun-photometer. The Li1200, an operational lidar in the frame of the Atmospheric Physics Reunion Observatory (OPAR), recorded the passage of an AAR during two nights. These measurements allow us to derive both the vertical structures of the plume and some vertically resolved aerosol optical properties. This information was used to constrain Lagrangian modelling tools to identify the pathways and origins of the biomass burning plume. These results have been corroborated by the spaceborne observations of CALIOP and CATS, and the passive sensor MODIS. Reanalysis of ECMWF with atmospheric composition outputs from the Copernicus Atmosphere Monitoring Service (CAMS) supports the understanding of the synoptic conditions leading to the formation of this aerosol plume configuration. We will present our scientific approach and discuss the environmental impact of these AARs in the southwest Indian Ocean.
Responses of subsoil organic matter contents and physical properties to long-term application of increasing amounts of manure
Authors: Wolff Maximilian
Published: March 2022

Application of farmyard manure (FYM) is common practice to improve physical and chemical properties of arable soil and crop yields. However, studies on effects of FYM application mainly focussed on topsoils, those in subsoils have been rarely been addressed so far. We, therefore, investigated the effects of a 36-year application of different FYM rates (0, 50, 100, 200 Mg ha−1 a−1) on organic carbon (OC) contents of a Chernozem in 0−30 cm (topsoil) and 35−45 cm (subsoil) depth, and its effects on soil structure and hydraulic properties in subsoil. X-ray computer tomography was used to analyse the response of macropore system (≥ 19 µm) and the distribution of particulate organic matter (POM) to different FYM applications. Based on morphological characteristics, POM was subdivided into a fresh and aged fraction. Image-derived POM volumes were related to contents in total OC (TOC) and water-extractable OC (WEOC) in order to differentiate between possible input sources of soil OC below the plough horizon. We show that manure application of up to 50 Mg ha−1 a−1 caused increases in TOC and WEOC contents only in the topsoil, whereas rates of ≥ 100 Mg ha−1 a−1 resulted in TOC enrichment also at deeper depth. In subsoil, the increase in POM (aged and fresh) and WEOC was more marked than that in TOC, indicating that POM and soluble OC may have facilitated the subsoil TOC enrichment. The subdivision of TOC into different OC sources shows that most of the increase was due to fresh POM, likely by roots. The increase in subsoil TOC went along with increases in macroporosity and macropore connectivity, possibly due to the stimulation of bioturbation. We neither observed increases in plant-available water capacity nor in unsaturated hydraulic conductivity. Our study shows that only very high applications of FYM over long periods can increase OC stocks of arable subsoil, but this increase is largely based on fresh, easily degradable POM and accompanied by high C losses.