bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Data Science Book: a community-driven resource showcasing open-source Environmental science
Authors: Coca-Castro Alejandro , Hosking Scott , Community The Environmental Data Science
Published: March 2022

With the plethora of open data and computational resources available, environmental data science research and applications have accelerated rapidly. Therefore, there is an opportunity for community-driven initiatives compiling and classifying open-source research and applications across environmental systems (polar, oceans, forests, agriculture, etc). Building upon the Pangeo Gallery, we propose The Environmental Data Science book (https://the-environmental-ds-book.netlify.app), a community-driven online resource showcasing and supporting the publication of data, research and open-source developments in environmental sciences. The target audience and early adopters are i) anyone interested in open-source tools for environmental science; and ii) anyone interested in reproducibility, inclusive, shareable and collaborative AI and data science for environmental applications. Following FAIR principles, the resource provides multiple features such as guidelines, templates, persistent URLs and Binder to facilitate a fully documented, shareable and reproducible notebooks. The quality of the published content is ensured by a transparent reviewing process supported by GitHub related technologies. To date, the community has successfully published five python-based notebooks: two forest-, two wildfires/savanna- and one polar-related research. The notebooks consume common Pangeo stack e.g. intake, iris, xarray, hvplot for interactive visualisation and modelling from Environmental sensor data. In addition to constant feature enhancements of the GitHub repository https://github.com/alan-turing-institute/environmental-ds-book, we expect to increase inclusivity (multiple languages), diversity (multiple backgrounds) and activity (collaboration and coworking sessions) towards improving scientific software practises in the environmental science community.
Elite consumptions trigger water shortages: Modelling heterogeneous interactions between drought and society
Authors: Savelli Elisa , Mazzoleni Maurizio , Rusca Maria , Cloke Hannah , Di Baldassarre Giuliano
Published: March 2022

Cities face increasing droughts and water shortages as a result of extreme meteorological conditions and expanding human pressure. Future projections estimate that over one billion urban residents will experience severe droughts and water shortages in the near future. Most scientific and policy debates emphasize climate change, population growth and urbanization as the major forces at the genesis of this apocalyptic future. In this paper we argue instead that the root causes of urban water crises have to be retraced in the socioenvironmental injustices enmeshed with the development of a city. For it is not society as a whole that reshapes drought events or trigger water shortages. Usually, the most powerful groups with greater privileges and access to resources, are those who play a more prominent role in decisions on water resource use and allocation, thereby shaping the propagation of drought phenomena more significantly.  Accounting for the heterogeneity of human societies is thus key to understand the dynamics of human-water systems and, more specifically, the temporal and spatial propagation of drought phenomena. Sociohydrological models have not yet accounted for the manners in which heterogeneous social groups intersect with drought propagation. This work advances current analyses by modelling heterogenous interactions between human and water systems alongside their unequal influences on the transformation of drought into uneven water crises. The Day Zero crisis in Cape Town constitutes the empirical basis of this work. On the one hand Cape Town’s urban geography epitomizes an unequal landscape of water access and vulnerabilities. On the other hand, Day Zero exemplifies an extreme drought event that will most likely occur across many urban areas. Using a system-dynamic framework we retrace the uneven consumptions of water across Cape Town metropolitan area and estimate the drought resilience trajectories for different social groups. In turn, the socio-hydrological model explores the distinctive implication that each trajectory has for the sustainability of urban water systems. Ultimately, we argue that the unsustainable water uses of the elite can transform a meteorological drought into an urban water crisis.
Stress triggering and the spectrum of fault slip behaviors
Authors: Pignalberi Federico , Scuderi Marco Maria , Noël Corentin , Marone Chris , Collettini Cristiano
Published: March 2022

Tectonic fault zones are subject to normal stress variations with a wide range of spatiotemporal scales, resulting in stress field alteration. These perturbations can spread over a wide range of frequencies and amplitudes from the high frequency passage of seismic waves generated by earthquakes, to the low frequency of solid earth tides and underground fluid injection cycles. As a result of these normal stress perturbations, critically stressed faults can be reactivated. The resulting slip mode is then controlled by fault friction and elastic properties of the surrounding rock. Existing works show that complex behaviors may arise from the interplay between friction changes with slip and slip rate and stress perturbations.

To shed light on the mechanics of fault dynamic triggering we performed experiments in a Biaxial Apparatus in a Double Direct Shear configuration under critically stable stiffness conditions (K/Kc~1). We used powdered quartz gouge (Min-U-Sil 40) as starting material, and conducted experiments at reference normal stress of σn = 10-13.5 MPa. After shearing the material and reaching a steady state sliding, normal stress oscillations were applied with various amplitudes, varying from A = 0.5-2 MPa, and periods, T = 0.5-50 s. In addition, we used the laboratory derived friction parameters as input for forward modeling using Rate-and-State friction laws in order to assess if these laws can explain our data. Our results show that creeping faults, under critical stiffness conditions, are sensitive to normal stress perturbations showing a variety of slip behaviors depending on amplitude and frequency of the oscillations:

Oscillation frequency has a major effect on fault stability. Low and high frequencies cause a Coulomb-like response of the shear stress, that is accompanied by a complex frictional response with slow events and period doubling. At the critical frequency predicted by the Rate-and-State friction, we observe dynamic weakening resulting in regular stick-slip events.

Oscillation amplitude also plays a role with the main effect depending on the magnitude of the perturbation.

Using a modified Rate-and-State equation (Linker and Dieterich, 1992), we are able to accurately model the laboratory data.

Our results show that normal stress perturbation on a laboratory creeping fault, at critical stiffness condition, can reproduce the entire spectrum of fault slip behavior depending on the oscillation properties.
Snow Avalanche Frequency Estimation (SAFE): 32 years of remote hazard monitoring in Afghanistan 
Authors: Caiserman Arnaud , Sidle Roy C , Gurung Deo Raj , Jarihani Ben
Published: March 2022

Snow avalanches are one of the most predominant natural hazards in mountain areas. Every year throughout the world, they are the cause of much material destruction and loss of life. It is therefore essential for local communities and public authorities to assess areas most vulnerable to avalanches. Here, we propose a new method for automatic avalanche detection from Landsat archives, using a snow index. This open-source and user-friendly model in Google Engine is the first to automatically inventory all the avalanches that have occurred each year across wide catchment areas, over a period of 32 years. The Snow Avalanche Frequency Estimation (SAFE) model was tested in the mountains of Afghanistan - Amu Panj Basin - one of the most remote regions in the world and one of the poorest in terms of avalanche monitoring. SAFE correctly detected 76% of the actual avalanches identified on Google Earth images and in the field. Since 1990, this region of Afghanistan has been impacted by 810,000 avalanches with an average frequency of 0.88 avalanches/km²yr-1. With SAFE, it is now possible to clearly identify villages, roads, and rivers that are frequently affected by avalanches and thus help decision-makers in their investments in avalanche protection infrastructure. It was also found that the frequency of avalanches has not changed over the last 32 years, but SAFE has identified a northeast shift of these hazards, notably due to a slight increase in temperatures in the south at the beginning of winter. SAFE is the first robust model that can be used worldwide and is capable of filling data voids on snow avalanche impacts in inaccessible regions.
Characteristics of pulse trains observed during the initial stage of high peak current winter flashes
Authors: Kolmašová Ivana , Santolík Ondřej , Pedeboy Stéphane , Kolínská Andrea , Amrich Samuel , Lán Radek , Uhlíř Luděk
Published: March 2022

Our study aims at initial stage of energetic negative cloud-to-ground (CG) winter lightning flashes. We analyze broadband magnetic-field measurements recorded in the West Mediterranean region in winter 2014/2015. By combining our data with information provided by the French national lightning locating system MÉTÉORAGE, we were able to select 200 waveform captures, which contained return stroke (RS) pulses emitted by negative CG discharges with peak currents exceeding 100 kA. The frequency band of our instrumentation (5 kHz-90 MHz) allowed us to investigate fine details of recorded waveforms. We found that the winter pre-stroke processes were very short, lasting on average only 1.7 ms from the first bipolar preliminary breakdown (PB) pulse to the following return stroke pulse.  The amplitudes of the strongest PB pulses reached on average only 25 % of the corresponding RS pulse. We investigate the evolution of peak amplitudes and inter-pulse intervals of PB pulses within individual PB trains. We found that in some trains the amplitudes of pulses were nearly monotonically increasing with time, they reached a maximum in a few hundreds of microseconds, and then decreased again being relatively regularly distributed in time. Within other PB trains, the pulses were chaotically spaced and their peak amplitudes did not show any trend. We assume that the short duration of the pre-stroke process indicate strong electric fields inside winter thunderclouds and hypothesize that the time evolution of PB pulse amplitudes and interpulse intervals reflect the spatial arrangement of the negative charge region.
Receiver Function analysis of noise reduced OBS data recorded at the ultra-slow spreading Knipovich Ridge
Authors: Rein Theresa , Zali Zahra , Krüger Frank , Schlindwein Vera
Published: March 2022

Ultra-slow spreading ridges are characterized by huge volcanic complexes which are separated by up to 150 km long amagmatic segments. The mechanisms controlling the ultra-slow spreading ridges are not yet fully understood. With the aim to better understand the spreading mechanisms and the flow of the magma beneath the volcanic complexes an ocean-bottom array has been installed along a segment of the ultra-slow spreading Knipovich Ridge in the Greenland sea. The array consists of 23 LOBSTER-type ocean bottom seismometers (OBS) from the DEPAS pool and 5 LOBSTERs from the Institute of Geophysics of the Polish Academy of Sciences. We aim to constrain the crustal and mantle structure beneath the segment of the Knipovich Ridge by using receiver functions calculated from teleseismic events.

Seismic data, recorded on the ocean bottom, are highly contaminated by different noise sources, which are dominating at frequencies below 1 Hz. During the experiment the DEPAS-LOBSTERs were equipped with a MCS recorder and a Güralp CMG-40T seismometer (changed now to 6D6 recorder and Trillium Compact seismometer). This characteristic design introduces electronic noise at selected stations at frequencies below 0.2 Hz. Recently head-buoy-strumming has been identified as additional noise source at frequencies above 0.5 Hz during tidal currents. Hence, most teleseismic signals are masked by the high noise level, especially on the horizontal components. However, a good signal to noise ratio on both, the vertical and horizontal components is crucial for seismological analysis, especially the receiver function method. Applying the HPS noise reduction algorithm on OBS data, as shown by Zali et al (submitted in 2021), allows to separate percussive or transient signals, such as the teleseismic earthquake from more harmonic and monochromatic signals, such as most of the noise generated at the ocean bottom.

The results of the HPS noise reduction algorithm processing of selected KNIPAS station data show a significantly reduced noise level below 1 Hz on all seismogram components, especially on the horizontals. Here, the signal-to-noise ratio increased by up to 3.2-3.7 (average by 1.4-1.6). The increased signal-to-noise ratio on the noise reduced data allows for more reliable receiver function results and their interpretation. Here, we show the reduced noise level on the OBS data and compare the receiver function results calculated from original data with the results from noise-reduced data.
Temperature-controlled erosion dominates in the Western Southern Alps of New Zealand
Authors: Roda-Boluda Duna , Schildgen Taylor , Wittmann Hella , Tofelde Stefanie , Bufe Aaron , Prancevic Jeff , Hovius Niels
Published: March 2022

The interplay of tectonics, climate, and erosion controls mountain topography, modulates Earth’s climate, and regulates the fluxes of sediments and solutes across Earth’s surface. Understanding and quantifying the complex processes behind this interplay remains one of the key challenges in the Earth Sciences. At the scale of mountain ranges, glacial erosion, river incision, and landsliding are the only processes that have been observed to be capable of balancing rapid rock-uplift rates. These processes are thought to link tectonics and climate through the influence of mountain elevations on orographic precipitation or glaciation.

The western Southern Alps of New Zealand (WSA) are one of the fastest-eroding ranges on Earth, where erosion has long been thought to be dominated by landsliding and glacial scouring. However, previous erosion studies in the WSA have been restricted to very few catchments, to decadal timescales, or to below the tree line, which has prevented evaluating the variables and processes controlling erosion at the orogen-scale over longer timescales. Here, 20 new in-situ 10Be catchment-averaged denudation rates, which mostly range between ~0.6-9 mm/yr, allow us to examine the controls and spatial distribution of denudation. We find that the proportion of catchment area within the 1500-2000 m elevation window explains >70% of the variability in denudation rates, more than any other variable. In the WSA, this elevation range is where temperatures most commonly fluctuate between -3ºC to -8ºC in the presence of water (the frost-cracking window), and includes the zone of recent glacial retreat and permafrost degradation. Our data hence suggests that temperature-controlled peri- and paraglacial erosional processes can balance some of the fastest rock-uplift rates on Earth, of several mm/yr. Therefore, these processes, which are also elevation-dependent, can play an important, but previously overlooked role in linking tectonics and climate and limiting mountain elevations.

 

 
Empirical modelling of SSUSI derived auroral ionization rates
Authors: Bender Stefan , Espy Patrick , Paxton Larry
Published: March 2022

Solar, auroral, and radiation belt electrons enter the atmosphere at polar regions leading to ionization and affecting its chemistry. Climate models with interactive chemistry in the upper atmosphere, such as WACCM-X or EDITh, usually parametrize this ionization and calculate the related changes in chemistry based on satellite particle measurements. Precise measurements of the particle and energy influx into the upper atmosphere are difficult because they vary substantially in location and time. Widely used particle data are derived from the POES and GOES satellite measurements which provide electron and proton spectra. These satellites provide in-situ measurements of the particle populations at the satellite altitude, but require interpolation and modelling to infer the actual input into the upper atmosphere.

Here we use the electron energy and flux data products from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instruments on board the Defense Meteorological Satellite Program (DMSP) satellites. This formation of currently three operating satellites observes both auroral zones in the far UV from (115--180 nm) with a 3000 km wide swath and 10 x 10 km (nadir) pixel resolution during each orbit. From the N2 LBH emissions, the precipitating electron energies and fluxes are inferred in the range from 2 keV to 20 keV. We use these observed electron energies and fluxes to calculate auroral ionization rates in the lower thermosphere (≈ 90–150 km), which have been validated previously against ground-based electron density measurements from EISCAT. We present an empirical model of these ionization rates derived for the entire satellite operating time and sorted according to magnetic local time and geomagnetic latitude and longitude. The model is based on geomagnetic and solar flux indices, and a sophisticated noise model is used to account for residual noise correlations. The model will be particularly targeted for use in climate models that include the upper atmosphere, such as the aforementioned WACCM-X or EDITh models. Further applications include the derived conductances in the auroral region, as well as modelling and forecasting E-region disturbances related to Space Weather.
Modelling volcanically induced climatic perturbations and their impacts on palaeodemography around 13ka BP in Europe
Authors: Andreasen Laurits , Riede Felix , Timmreck Claudia
Published: March 2022

Climate and human populations can be said to make up a complex system with many possibilities for one component to impact another. Present day global warming is one example, yet examples are not limited to the Anthropocene but can also be found in the deep past.  The Laacher See Eruption (LSE) that occurred around 13,000 BP is one example of how climate, the environment and human palaeodemography interacted. Archaeological findings suggest the LSE potentially had strong and long-lasting impact on contemporary hunter-gatherer societies in some parts of Europe – in some sense the memory of the impact might even be considered infinite and hysteresis-like, since culture might have changed more permanently in the eruption’s wake. We investigated the climatic legacy of the LSE using computer-based models. This requires a model suite that deals with both physical, environmental, and demographical variables. For this we combine the MPI Earth System Model with a statistical model that estimates population densities and information on generation times in hunter-gatherer societies. This configuration allows us to estimate the size and duration of the impact the LSE had on climate variables and - via changes in the carrying capacity - palaeodemography. Our findings suggest that the palaeodemography of Late Glacial hunter-gatherer societies showed a memory of the initial environmental perturbation at a temporal scale exceeding that of the transient perturbation itself. The memory found in our models is, however, relatively short-lived, which could reflect the actual memory of the physico-social system, or limitations of our modelling approach. Further evaluation of the model against archaeological sites is needed to suggest what is the case.
Application of the Generalized Method of Wavelet Moments to the analysis of daily position GNSS time series.
Authors: kermarrec gael , cucci davide , montillet jean-philippe , guerrier stephane
Published: March 2022

The modelling of the stochastic noise properties of GNSS daily coordinate time series allows to associate realistic uncertainties with the estimated geophysical parameters (e.g. tectonic rate, seasonal signal). Up to now, geodetic software based on Maximum Likelihood Estimation (MLE) jointly inverse a functional (i.e. geophysical parameters) and stochastic noise models. This method suffers from a computational time exponentially increasing  with the length of the GNSS time series, which becomes an issue when considering that the first permanent stations were installed in the late 80’s – early 90’s having recorded more than 25 years of geodetic data. Combining this issue with the tremendous number of permanent stations blanketing the world (i.e. more than 20,000 stations), the processing time in the analysis of large GNSS network is a key parameter. 

Here, we propose an alternative to the MLE called the Generalized Method of Wavelet Moments (GMWM). This method is based on the wavelet variance, i.e. a decomposition of the time series using the Haar wavelet. We show the first results and compare them with the MLE in terms of computational efficiency and absolute error on the estimated parameters. The versatility of this new method is its flexibility of choosing various stochastic noise models (e.g., Matérn, power law, flicker, white noise, random walk), and its robustness against outliers. Additional developments to account for deterministic components such as seasonal signal, offsets or post-seismic relaxation is easy. We explain the principle beyond the method and apply it to both simulated and real GNSS coordinate time series. Our first results are compared with the estimation using  the Hector software.
Drivers of LGM AMOC change from PMIP2 to PMIP4
Authors: Klockmann Marlene , Sherriff-Tadano Sam
Published: March 2022

Understanding the response of the Atlantic Meridional Overturning Circulation (AMOC) to different climate conditions is a crucial part of understanding the climate system. Proxy-based reconstructions suggested that the AMOC during the Last Glacial Maximum (LGM) was likely shallower than today. Generations of climate models from PMIP2 to PMIP4 have shown large inter-model differences and often struggled to simulate a shallower AMOC. In the present study, we revisit hypotheses that have emerged over time and test them consistently across the PMIP ensembles from phase 2 to 4. We start by repeating the analyses by Weber et al (2007), who showed that there was a relationship between the glacial AMOC change and the density difference between the Southern Ocean and the subpolar North Atlantic in many PMIP2 models. Additional analysis will include hydrographic changes (e.g., stratification, water mass properties), the role of global and local LGM cooling as well as biases in the models. In our model evaluation, we will also consider recent reconstructions based on multi-proxy evaluations which indicate that the response of the glacial AMOC geometry and strength may have been less unambiguous than previously thought.
Response of the Aegean Sea surface characteristics to turbidity variations, using numerical simulations.
Authors: Metheniti Vassiliki , Vervatis Vassilios , Karageorgis Aristomenis P. , Kampanis Nikolaos , Sofianos Sarantis
Published: March 2022

The thermohaline and dynamic characteristics of the upper ocean can be affected by the way the sunlight is absorbed and scattered on the surface layer. Changes in light penetration can be investigated through the turbidity of the layer, which is determined by a synthesis of terrestrial inputs (atmospheric and riverine), and the biological activity in a region, of both natural and anthropogenic origin. To examine the effects that turbidity variability has on the surface-layer characteristics of the ocean, a twin modeling sensitivity experiment was performed, using as a case study the Aegean Sea, NE Mediterranean. The Aegean Sea is an oligotrophic region with most nutrient inputs located in the northern coasts of the basin, creating a north-to-south chlorophyll-a gradient, with the highest concentrations on the North and lowest on the South. The first experiment corresponds to a very clear ocean, and the second incorporates the turbidity field, varying according to chlorophyll-a concentration.
The experiments were implemented using the NEMO models' ocean component (v3.6) for the region (34.05-41.16 °N, 22.29-28.98 °E) and for the period 1997-2001, discretized on a 1/36° Arakawa-C grid, with 75 partial step vertical levels. Atmospheric inputs are ERA-5 reanalysis products of the ECMWF service, whereas inputs for initial and boundary values have been derived from the Copernicus database. First, a two-band light penetration scheme was applied, using a Jerlov Type-I extinction depth at 23.0 m, representing the constant-low turbidity field. An RGB scheme was applied for the second experiment, using the multiyear monthly mean of the chlorophyll-a concentration variable derived from the ESA-CCI service. The sea surface variables' response is examined for the final year of the experiment. The results indicate that the RGB-scheme experiment estimates elevated sea surface salinity and temperature values, with the most significant difference in salinity located in the northern part of the basin, where there is a strong influence of the inflow of Black Sea Water from the Dardanelles Straits. Elevated eddy kinetic energy is observed in the gyres formed in the Cretan Sea.
Lagrangian approach of the mixing in a turbulent thermal, and implications for metal-silicate equilibrium during Earth's formation
Authors: Huguet Ludovic , Deguen Renaud
Published: March 2022

During the differentiation of terrestrial planets, the metal phase from the impactor core segregates from the silicate phase of the magma ocean. This buoyant mass forms a turbulent thermal and settles toward the proto-core. During this descent, thermal and chemical exchange occurs at the boundary between the metallic and silicate phases. Based on laboratory fluid dynamic experiments mimicking the settling of the metallic thermal turbulent, we develop a Lagrangian approach of the mixing from the experimental velocity field. We are able to track the evolution of the material elongated as lamellae by the turbulent stirring. We have characterised the elongation rate, the aggregation of lamellae, and the probability density function of the elongation and concentration, which are not accessible from direct measurements in the experiments. We have also investigated the effect of the Reynolds number and density ratio on these quantities. These results will allow us to develop a new predictive model of the mixing and chemical transfer in thermal turbulent to better understand the equilibrium between metals and silicates during the accretion of terrestrial planets.
Arctic temperature responses to East Asian and European anthropogenic organic carbon emissions: impacts of externally vs internally mixed aerosols
Authors: Im Ulas , Tsigaridis Kostas , Ekman Annika M.L. , Hansson Hans-Christen
Published: March 2022

Fully coupled equilibrium simulations have been performed using the NASA Goddard Institute of Space Sciences (GISS) Earth system model (GISS-E2.1.2), where the East Asian and European land-based anthropogenic organic carbon (OC) emissions have been perturbed by five and seven times, respectively. GISS-E2.1.2 has been driven by the Coupled Model Intercomparison Project Phase 6 (CMIP6) anthropogenic emissions. GISS-E2.1.2 simulations have been performed using both the one moment aerosol (OMA) and the Multiconfiguration Aerosol TRacker of mIXing state (MATRIX) aerosol models, respectively, to quantify the impact of aerosol optical properties and the mixing state assumptions, i.e., external mixing in OMA vs internal mixing in MATRIX. 70 years of baseline and perturbation simulations have been performed for the year 2000 using a 5-member ensemble, where the last 30 years of simulations have been used for analyses.

In the present study, we will present the impact of the aerosol optical properties and mixing state on the OC and black carbon (BC) burdens and lifetimes, as well as the Arctic surface temperature response to the East Asian and European OC emissions in the form of regional temperature potentials (RTP). The preliminary results showed the OMA model simulated a general decrease in the global surface temperatures in response to the East Asian OC emissions, with no statistically significant response over the Arctic, while the MATRIX model showed increases over the globe, including statistically significant increases over the Arctic. Overall, the Arctic RTP in response to the East Asian OC emissions are -0.02 K Tg-1 and +0.00003 K Tg-1 using the OMA and MATRIX aerosol models, respectively.
A multi-isotopic approach to the reconstruction of palsa hummock formation: the case study from the Central Siberia
Authors: Prokushkin Anatoly , Novenko Elena , Serikov Sergey , Polosukhina Daria
Published: March 2022

In northern palsa mires stable isotopes of C and N of peat organic matter (OM) and O and H of segregated ice may serve as an important conduit of information about variability of environment conditions and OM turnover in the past millennia and modern time. In our study we applied the multi-isotopic record to distinguish variation in the development of palsa peatlands located in forest-tundra ecotone of Central Siberia.

The study sites are located in vicinity of Igarka settlement (67o31’ N, 86o38’E) within the area underlain discontinuous permafrost. The peat cores were obtained in the central intact parts of perennial frost hummocks located in basins of the Gravijka and Little Gravijka rivers (depth 8.6 and 2.7 m, respectively). Thawed and frozen peat samples were collected at 1.0-5.0 cm step depending on the amount of peat and ice material. Peat (solid) samples were analyzed for C and N content and stable isotopic composition (δ13C and δ15N) by TOC Macro cube (Elementar, Germany) paralleled with Isoprime 100 IRMS (UK). Water stable isotope composition (δ18O and δ2H) of segregated ice samples (melted) were obtained by Picarro L-2120-i (Picarro Inc. USA).

The age of studied peatlands ranged between about 6200 cal yr BP (Gravijka site) and 4300 cal yr BP (Little Gravijka site). Meanwhile, there was the large loss of organic matter in the upper active layer of peat deposits as at 15 cm depth the age of OM was ca. 1800 cal yr BP. These findings suggest OM removal during wildfires and likely erosion processes following fires, and specific isotopic composition mirrors an enhanced OM decomposition in active layer. The large variations in composition of analyzed stable isotopes in frozen peat core captured the changes occurred during the past epochs in an input of OM (changes in vegetation and productivity), peat decomposition rates, nitrogen cycle perturbations as well as hydrothermal regimes and permafrost processes like aggradation (e.g. hummock uplift and cryoturbation) and degradation (e.g. hummock collapse, shifts from minerotrophic to ombrotrophic conditions and vice versa).

This work was supported by the Russian Science Foundation, project № 20-17-00043.
Stem distance as an explanatory variable for the spatial distribution and chemical conditions of stand precipitation and soil solution under beech (Fagus sylvatica L.) trees
Authors: Jochheim Hubert , Lüttschwager Dietmar , Riek Winfried
Published: March 2022

The partitioning of bulk precipitation (PR) in forest ecosystems and its chemical composition depends on both meteorological factors, such as precipitation amount and intensity, evaporation rate, and wind speed, and stand structural factors, such as stand density, canopy structure, bark texture, and spatiotemporal distribution and density of foliage. We analysed fluxes of water and element contained therein of a mature European beech (Fagus sylvatica L.) forest stand on sandy soils in northeastern Germany. We applied a radially symmetrical setup within a stem distance gradient to measure stand precipitation (SP) with its components of throughfall (TF) and stemflow (SF), as well as to measure soil moisture, the chemical composition of the soil solution, the soil chemistry, and the fine root distribution. The chemical analysis of the constituents covered the macroelements (Ca, Mg, K, Na, Al, Fe, Mn, Si, S, P), the cations and anions NH4+, NO3-, Cl-, SO42-, and a few heavy metals (Cu, Pb, Zn). With an average PR of 620 mm a-1, the partitioning resulted in 79% TF, 6% SF, and 15% canopy evaporation. TF volume increased with distance to stem during summer, but decreased during winter. Clear spatial gradients with increasing concentrations from PR, to different classes of TF as the distance from the trunk decreased, to SF were observed for nearly all elements. The contact of precipitation with leaves and the canopy structures alters the chemical composition of TF and SF by transferring elements from dry deposition or leaching of intracellular materials from the canopy and leads to the input of larger amounts of macroelements and heavy metals with the SP into the soil. Spatial patterns of canopy structures thus affect the spatial variation of TF and its constituents, which also affects the spatial distribution of roots and, at least in phases, the chemical composition of the topsoil solution.
Impact of initial soil moisture on the hydrological response: Application for flood forecasting in the Mediterranean mountainous watershed.
Authors: Benkirane Myriam , Laftouhi Nour-Eddine , Khabba Said
Published: March 2022

Mediterranean mountainous regions are strongly affected by flash flood events causing many damages. The vulnerability to flooding in the Moroccan High Atlas, especially in the Tensift basin, has been increasing over the last decades. Rainfall-runoff models can be very useful for flash flood forecasting. However, event-based models require a reduction of their uncertainties related to the estimation of initial moisture conditions before a flood event. Soil moisture may strongly modulate the magnitude of floods and is thus a critical parameter to be considered in flood modeling.

Indeed, several studies have assimilated satellite soil moisture observations into rainfall-runoff models to improve their flood forecasting capabilities.

In order to have a better representation of the watershed states which leads to a better estimation of the streamflow. By exploiting the strong physical connection between soil moisture dynamics and precipitation, it has been shown that satellite soil moisture observations can also be used to improve the quality of precipitation observations.

The aim of this study is to compare daily soil moisture measurements obtained by time domain reflectometry (TDR) at Sidi Rahal station with satellite soil moisture products (European Space Agency Climate Change Initiative, ESA-CCI), in order to estimate the initial soil moisture conditions for each event. The systematic bias between soil moisture products and in situ measurements was corrected using a bias correction method. The correlations between soil moisture products and in situ observations are about 0.77 after the correction.  

However, a modeling approach based on rainfall-runoff observations of 30 sample flood events have been applied, from (2011 to 2018), in the Ghdat basin were extracted and modeled by an event-based rainfall-runoff model (HEC-HMS) which is based on the Soil Conservation Service (SCS-CN), loss model, and a Clark unit hydrograph was developed for simulation and calibration of the 10-minute rainfall runoff.

A similar approach could be implemented in other watersheds in this region for further operational purposes. This method is very satisfactory for reproducing rainfall-runoff events in this small Mediterranean mountainous watershed, the same approach could be implemented in other watersheds in this region. The results of this study indicate that the remote sensing data are theoretically useful for estimating soil moisture conditions in data-sparse watersheds in arid Mediterranean regions.

Keywords: Soil moisture; Floods; Remote sensing; Hydrological modelling, CN method, Mediterranean basin.
Flood inundation mapping using 2-d streamflow hydraulic modeling and land subsidence data from InSAR observations in the Alto Guadalentin valley, Spain.
Authors: Navarro-Hernández María , Valdés-Abellán Javier , Tomás Roberto , Tessitore Serena , Ezquerro Pablo , Herrera Gerardo
Published: March 2022

Floods are natural extreme events that occur after heavy rains, having a great impact on human settlements developed along flood risk areas (such as floodplains, valleys, etc.). Alto Guadalentin Valley is an orogenic tectonic depression affected by extreme flash floods. Additionaly, this area is affected by the fastest subsidence in Europe with a rate up to -10 cm/year due to groundwater withdrawal. In this study we present two flood event 2-D models comparison between different time land subsidence scenarios (1992 and 2016). The flood inundation modelling was performed in the Alto Guadalentin River and their tributaries using the Hydrologic Engineering Center River Analysis System 2D (HEC-RAS 2D) model, for the purpose of determining the flooded area extent and the depth water variations produced by the effect of land subsidence over time. To recreate both scenarios, different sets of synthetic aperture radar (SAR) images acquired by ERS (1992-2000), ENVISAT (2003-2010) and Cosmo-Skymed (2011-2016) satellites were used to calculate the magnitude and  spatial distribution of land subsidence using SAR Interferometry (InSAR) technique. The subsidence accumulated between 1992 and 2009 and between 2009 and 2016 derived from InSAR was substracted and added, respectively, to a Digital Surface Model (DSM) with 2.5 m spatial resolution from 2009 obtained using Light Detection and Ranging (LiDAR) to obtain the actual topography of the valley before (i.e. 1992) and after (i.e. 2016) the subsidence period covered by InSAR. These DEMs were used to generate the two 2D hydraulic models that ran in an unsteady mode. The results revealed significant changes in the water surface elevation with an increase of 3,073,200 m2 in the areas with depth water greater than 0.8 m over 24 years. From these simulation a flood risk map was performed. The resulting flood hazard data provides useful information to understand the inundation risk taking into account land subsidence contribution in the Alto Guadalentin Valley. This information can be of paramount importance for emergency management and civil protection against future potential floodings.
Strong control of effective radiative forcing and precipitation by the spatial pattern of absorbing aerosol
Authors: Williams Andrew , Stier Philip , Dagan Guy , Watson-Parris Duncan
Published: March 2022

The spatial pattern of anthropogenic aerosol has changed markedly over the historical period and is expected to continue evolving in the coming decades. Additionally, the global composition of anthropogenic aerosol is expected to become relatively more absorbing because policy measures often target sources of scattering and absorbing aerosols differently. However, despite these historical and future changes,  relatively little attention has been given to the potential climatic impacts of the evolving spatial pattern of absorbing aerosol.

In this talk, we will present results from a large ensemble of idealised aerosol absorption experiments with a state-of-the-art climate model to show that the global-mean effective radiative forcing (ERF) from absorbing aerosol strongly depends on their location, driven by rapid adjustments of clouds and circulation. Furthermore, by viewing absorbing aerosol as a localised diabatic heating source we will provide an explanation for this location-dependence of ERF in terms of simple atmospheric dynamics. We will also demonstrate how this approach can be used to understand the sensitivity of local and global precipitation to realistic and idealised changes in the spatial pattern of absorbing aerosol. 

Our results have implications for understanding the climatic impacts of regional aerosol absorption and demonstrate the utility of an ensemble approach to understanding the impacts of variations in the spatial pattern of aerosol.
Relative Humidity (RH) distribution in the extratropical upper troposphere and lowermost stratosphere: Long-term evolution derived from in-situ observations of the combined IAGOS and MOZAIC time series
Authors: Rohs Susanne , Smit Herman , Bundke Ulrich , Kennert Marcel , Blomel Torben , Gläser Jennifer , Petzold Andreas
Published: March 2022

The European research infrastructure IAGOS (In-Service Aircraft for a Global Observing System; www.iagos.org) and its predecessor MOZAIC (Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft) is a global observation system for atmospheric composition by deploying autonomous instruments aboard a fleet of commercial passenger aircraft. The combined time series spans now more than 25 years and is comprised of more than 60000 flights.  This makes it ideally suited for atmospheric research on a statistical basis.

Previous results, investigating the MOZAIC period, have already given insights into the seasonal and regional variability of the Relative Humidity (RH) distribution and the regions with ice-supersaturated air masses (ISSR). Thereby, significant ISSR occurrence exists in the Ex-UTLS (Petzold et al., ACP, 2020, doi.org/10.5194/acp-20-8157-2020), a region in which the distribution of water vapour shows a large spatial and temporal variability.

In the present study, we extend this study by using the combined time series from 1996 to 2020 for the long-term characterization of RH distribution in the Ex-UTLS. We will focus on comparing the distribution of RH for different years and seasons and analyzing the time series for potential long term trends.
Legacy DSDP and ODP data suggest a paradigm shift in methane hydrate stability in the Mediterranean Basin
Authors: Corradin Cristina , Camerlenghi Angelo , Giustiniani Michela , Tinivella Umberta , Bertoni Claudia
Published: March 2022

The global reservoir of submarine gas hydrates is favored by the cold temperature of oceanic bottom water and the generally low geothermal gradients along passive continental margins. The continental margins of the land-locked Mediterranean basin are a remarkable exception for the lack of evidence of extensive presence of gas hydrates. Using public data of the physics and chemistry of the subsurface available from 44 Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) wells as lithologic logs, downhole temperature measurements, and pore water salinity values, and observed physical characteristics of bottom waters, we model the theoretical methane hydrate stability zone (MHSZ) below the seafloor and in the water column.

We find important positive pore water salinity anomalies in the subsurface indicating the pervasive presence of concentrated brines up to saturation concentration of halite and gypsum (> 300 ‰). The resulting sub-bottom MHSZ is thinner by up to 90-95% with respect to its thickness calculated assuming constant salinity with depth equal to bottom waters salinity. In the Eastern Mediterranean deep basins the thickness of the subsurface MHSZ is largest (up to ~ 350 m) and the anomaly induced by subsurface brines is highest (~ -300 m), while in the Alboran, Western Mediterranean, Tyrrhenian, Sicily Channel, Adriatic and Aegean basins the MHSZ, where present, thins to less than 100 m with mostly negligible anomaly induced by the presence of subsurface brines.

Modelling results suggest that subsurface brines can produce dramatic reductions of the thickness of the MHSZ only where the geothermal gradient is low (Eastern Mediterranean). We have modelled the same brine-induced limiting effect on the thickness of the MHSZ in synthetic cases of high and low heat flow to simulate Western and Eastern Mediterranean subsurface thermo-haline conditions. The salinity effect is attenuated by the thermal effect in the Western Mediterranean that produces the most relevant thinning of the MHSZ.

The distribution of the MHSZ resulting from the modelling coincides well with the distribution of the Late Miocene salt deposits which limit further the possibility of formation of gas hydrates acting as low permeability seal to the up-ward migration of hydrocarbon gases.

This modelling exercise provides a robust explanation for the lack of evidence of widespread gas hydrates on Mediterranean continental margins, with the exception of areas of local methane upward advection such as mud volcanoes, and it outlines a number of local hydrate-limiting factors that make this basin unfavorable to gas hydrate occurrence.
Preliminary results of investigation of “unidentified fault” associated with the Mw 7.3 Flores Sea earthquake
Authors: Supendi Pepen , Rawlinson Nicholas , Prayitno Bambang Setiyo , Widiyantoro Sri , Palgunadi Kadek Hendrawan , Simanjuntak Andrean , Kurniawan Andri , Marliyani Gayatri Indah , Nugraha Andri Dian , Daryono Daryono , Fatchurochman Iman , Sadly Muhammad , Adi Suko Prayitno , Karnawati Dwikorita , Gunawan Mohammad Taufik , Arimuko Abraham
Published: March 2022

On December 14, 2021, the Mw 7.3 Flores Sea earthquake occurred approximately 100 km to the north of Flores Island, one of the most complex tectonic settings in Indonesia. The existence of the causative fault that generated this earthquake was not been previously known, therefore making further analysis crucial for assessing future seismic hazard in the region. In this study, we relocated the hypocenter of the mainshock and aftershocks using a double-difference method, determine focal mechanisms using waveform inversion, and then analyse stress changes to estimate the fault type and stress transfer caused by this earthquake. Our relocated hypocenters show that this earthquake sequence ruptured on at least three segments: the source mechanism of the mainshock exhibits dextral strike-slip motion (strike N288oW and dip 78o) that occurred on a West-East trending fault which we call the Kalaotoa Fault, while rupture of the other two segments located to the west and east of the mainshock (WSW-ESE directions, respectively) may have been triggered by this earthquake. The Coulomb stress change of the mainshock shows that areas to the northwest and southeast experienced an increase in stress, which is consistent with the observed aftershock pattern.
Towards Canopy parameterization for Multiscale Finite Element Method
Authors: Patel Heena , Simon Konrad , Behrens Jörn
Published: March 2022

Canopies represent sub-grid scale features in earth system models and interact as such with the large-scale processes resolved numerically. The canopy is implemented with a viscosity approach, resembling a roughness parameterization. However, the idea is that high viscosity is applied locally to an obstacle area whereas free spaces are assigned low viscosity. In a first step, we test this approach on a micro-scale, using an advection-diffusion equation to solve for tracer transport around obstacles. Available wind tunnel data are used for validation of a standard finite element implementation. In a second step, this approach is combined with a multi-scale finite element approach, such that a large-scale simulation can be coupled to the micro-scale representation of a canopy. Comparison of high-resolution standard finite element and low-resolution multi-scale finite element methods will allow for quantitative error analysis. This approach has the potential to lead to better parameterizations of subgrid-scale processes in large-scale simulations.