bluuebunny/crossref_metadata_2025 huggingface dataset:
The Channel Source Hypothesis: Empirical Evidence for In-Channel Sourcing of Dissolved Organic Carbon to Explain Hysteresis in a Headwater Mountain Stream
Authors: Ward Adam , Wondzell Steven
Published: March 2022

Catchment hydrologists have long puzzled over the question: How can catchments rapidly generate storm flows in response to storm events? That question is complex because changes in stream water chemistry during storms suggest that proportions of old (or pre-event) water and new (or event) water also change during the storm. Conceptual models viewing catchments as composed of discrete source areas generating flow at unique time scales and with unique chemical characteristics have been used to explain the observed changes in flow and water chemistry. Surprisingly, those conceptual models usually do not treat the stream channel as one of the potential source areas. Here, we propose the channel source hypothesis in which the stream itself should be considered as a potential source with the same rigor as other contributing areas. We pose this in the spirit of the scientific use of the word: a hypothesis[1] is not a proven idea but rather a provisional supposition serving as the basis for further study. We suggest that the channel should be considered as a potential source for dissolved organic carbon (DOC). Channels store substantial amounts of organic matter, and stream ecologists have long studied stream carbon cycling. From those studies we know that leaching and decomposition can generate DOC from particulate organic carbon (POC). Further, POC is stored in channel “dead-zones” - regions of low flow velocity - that can be activated as flow velocity increases, thus releasing accumulated DOC during storms. All catchments are different; there is no reason to assume that channel sources are always important, in every catchment, in every storm. Thus, the channel source hypothesis does not replace existing conceptual models. Instead, it adds another potential mechanism that may explain DOC dynamics observed in streams. The channel source hypothesis has substantial implications for catchment studies examining sources of DOC in stream water or using DOC as a tracer to determine the locations of, and proportional contributions of, different source areas for streamflow generation.

[1] Hypothesis: "a provisional supposition from which to draw conclusions that shall be in accordance with known facts and serves as a starting point for further investigation by which it may be proved or disproved and the true theory arrived at" quoted from the Oxford English Dictionary (OED), 1985.

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Iron mobility in slab-derived hydrous silicate melts at sub-arc conditions
Authors: Tiraboschi Carla , Arno Rohrbach , Stephan Klemme , Jasper Berndt , Carmen Sanchez-Valle
Published: March 2022

Aqueous and saline fluids have a fundamental role in subduction zones and represent a major vector of mass transfer from the slab to the mantle wedge. In this setting, assessing the mobility of redox sensitive elements, such as iron, in aqueous fluids and melts is essential to provide insights on the oxygen fugacity conditions of slab-derived fluids and the oxidation state of arc magmas.

We experimentally investigate the solubility of magnetite and hematite in water-saturated haplogranitic melts, which represent the felsic melt produced by subducted eclogites. Experiments were conducted at 1–2 GPa and temperature ranging from 700 to 950 °C employing an endloaded piston cylinder apparatus. Single gold capsules were loaded with natural hematite, magnetite and synthetic haplogranite glass. Two sets of experiments were conducted: a first set with pure H2O and a second set with a 1.5 m H2O-NaCl solution. After quench, the presence of H2O in the haplogranite glass was verified by Raman spectroscopy, while iron and major element contents were determined by electron microprobe analysis.

Results show that a significant amount of FeO is released from magnetite and hematite equilibrated with hydrous melts, up to 1.96 ± 0.04 wt% at 1 GPa and 950 °C. In the presence of NaCl, we observed an increase in the amount of iron in the haplogranite glass, e.g. from 1.04 ± 0.12 wt% to 1.50 ± 0.31 wt% of FeOtot at 800 °C. These concentrations are substantially higher than the iron solubility in aqueous and saline fluids predicted by thermodynamic modelling (DEW model, Sverjensky et al., 2014), likely due to formation of Fe- and Si-bearing complex in the haplogranite-bearing fluid at run conditions. Our results suggest that hydrous melts can effectively mobilize iron from Fe-oxides even at relatively low-pressure conditions. Slab-derived hydrous melts can thus represent a valid agent for mobilizing iron from the subducting slab to the mantle wedge, and can strongly influence the geochemical cycles of Fe and the redox conditions of subduction zone fluids.

 

Sverjensky, D. A., Harrison, B. and Azzolini, D. (2014) Water in the deep Earth: The dielectric constant and the solubilities of quartz and corundum to 60kb and 1200°C, Geochim. Cosmochim. Acta, 129, 125–145
Multiobjective and real-options based planning for adaptive and robust water resources
Authors: Erfani Tohid , Pachos Kevis , Huskova Ivana , Matrosov Evgenii , Harou Julien
Published: March 2022

Planning for sustainable future water resources needs to consider multiple goals like cost and resilience. The ability to adapt given uncertainties about climate change, population growth and other unknowns should be embedded into planning approaches. Adaptive planning can help meet future needs and reduce the risk of over-investment, capitalizing on the upside situation of future supply-demand balances being less stressed than anticipated. In this study, we propose a multi-objective real-options based multi-stage formulation well- suited to regulated water utilities with a regular planning cycle. The formulation can be used to explore the trade-offs between long term water management plan’s resilience and financial costs while considering the effects of different types of demand growth and supply side uncertainties. Using London's water resource and supply system as a case study, we demonstrate how the generalized approach can be applied to reveal the cost-resilience trade-off delineated by different efficient planning alternatives.
Modeling River hydro-morphological responses to Land Use Land Cover Change in Tropical Regions, case of Sebeya catchment, Rwanda.
Authors: Kayitesi Manishimwe Naomie , mariethoz gregoire
Published: March 2022

Tropical regions have experienced rapid Land Use Land Cover Change (LULCC) in the last decades. Furthermore, climate change will likely intensify these changes due to global warming and increased frequency of extreme events. These changes have diverse effects on watershed and river hydro-morphological processes through alterations of the rainfall and runoff patterns, which translate into changes in the water balance components. The magnitude of these effects depends on the watershed characteristics, including the size, extent of change, topography, soil characteristics, and climate. Understanding the watershed hydro-morphological responses to changes in both climate and LULC –especially in tropical regions where rainy seasons are followed by dry seasons— is vital for effective land and water resources management in the face of future changes.

Sebeya catchment in the western part of Rwanda is prone to flooding, associated with erosive processes, and mass movements. Hence, destroying infrastructures and houses, damaging crops, and taking people’s lives yearly during long rainy season (February to May). This is partly attributed to the combination of steep topography and the loss of forest cover on fragile soils, coupled with the increased prevalence of extreme rainfall events. The hypothesis is that the hydro-morphological characteristics of Sebeya river have changed in the last few decades as a result of LULCC, including forest clearing from agriculture and built-up development. In light of it, this study intends to quantify changes in LULC of the Sebeya catchment over the last three decades, and predict future changes in the next three decades, using remote sensing data and LULC model. Furthermore, a hydrologic model will be used to simulate and forecast the associated changes in hydro-morphological and flood frequency.
Self-consistent Monte-Carlo modeling of the November 10, 2012 energetic storm particle event
Authors: Afanasiev Alexandr , Talebpour Sheshvan Nasrin , Vainio Rami , Dresing Nina , Trotta Domenico , Hietala Heli , Nyberg Seve
Published: March 2022

Fluxes of solar energetic particles (SEPs) are associated with solar flares and coronal/interplanetary shock waves. In the case of shocks, particles are thought to get accelerated to high energies via the diffusive shock acceleration mechanism. In order to be efficient, this mechanism requires an enhanced level of magnetic turbulence in the vicinity of the shock front, in particular, in the so-called foreshock region upstream of the shock. This turbulence enhancement can be produced self-consistently, i.e., by the accelerated particles themselves via streaming instability. This idea underlies the SOLar Particle Acceleration in Coronal Shocks (SOLPACS) Monte-Carlo simulation code, which we developed earlier to simulate acceleration of protons in coronal shocks. In the present work, we apply SOLPACS to model an energetic storm particle (ESP) event measured by the STEREO A spacecraft on November 10, 2012. All but one main SOLPACS input parameters are fixed by the in-situ plasma measurements from the spacecraft. Comparison of a simulated proton energy spectrum at the shock with the observed one then allows us to fix the last simulation input parameter related to efficiency of particle injection to the acceleration process. Subsequent comparison of simulated proton time-intensity profiles in a number of energy channels with the observed ones shows a very good correspondence throughout the upstream region. Our results give support for the quasi-linear formulation of the foreshock. This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0).
Characterization of the tephra deposit associated with the 2021 eruption of Cumbre Vieja (La Palma)
Authors: Bonadonna Costanza , Pistolesi Marco , Voloschina Marija , Reyes Hardy Maria-Paz , Dominguez Lucia , Martin Alba , Romero Moyano Jorge Eduardo , Pastore Camille , Andronico Daniele , Cimarelli Corrado , Coldwell Beverley , Kueppers Ulrich , Rodríguez Fátima , Pankhurst Matt , Polacci Margherita , Scarlato Piergiorgio , Taddeucci Jacopo
Published: March 2022

Between 19 September and 13 December 2021 (85 days), a flank eruption took place along the Cumbre Vieja ridge (La Palma Island), one of the most active volcanic centers of Canary Islands. The last 7000 years of Cumbre Vieja activity has been characterized by a combination of effusive and explosive eruptions. These generated both cinder cones and lava flows. The previous event occurred between October 26 and November 28, 1971 (eruption of Teneguía). The 2021 eruption was characterized by the alternate (and often simultaneous) emission of lava flows, lava fountains and tephra plumes along a ~1 km-length fissure consisting of about ten vents that built a cinder cone complex. The southern vents were mostly associated with the generation of tephra plumes and lava fountains, while the northern vents were mostly associated with the generation of lava flows. The ~12 km2 lava flow field on the west side of the island reached the sea on September 28, forming a new lava delta and interacting with sea water producing lava haze (i.e. laze). Even though tephra was sedimented all over La Palma and sometimes reached the neighboring islands, the cumulative tephra deposit is mostly elongated towards the southwest and the northeast due to the prevailing wind direction, reaching a maximum thickness southwest of the fissure. Both lava fountains and more explosive tephra plumes contributed to the formation of the tephra deposit. Tephra plumes were associated with variable intensity reaching a few kilometers of altitude (<10 km). Multiple tephra layers, which are associated with distinct phases of the eruption, can be identified based on grainsize, clast texture and deposit characteristics. Some of the layers are dominated by black fluidal glassy clasts mostly associated with lava fountain activity, while some others are dominated by brown, finely to coarsely vesicular clasts mostly associated with more explosive tephra plumes. Most layers, as well as the cumulative deposit, are characterized by a thinning break-in-slope between 3-4 km from the vents. A distinctive lithic-rich, reddish layer, which mostly sedimented on October 15-16 during a new vent opening phase, helps the correlation among the various layers. Grainsize on land is dominated by lapilli and coarse ash, with fine ash being mostly deposited in the ocean (beyond 6 km from the vents). Individual layers are associated with volumes that range between Volcanic Explosivity Index (VEI) 2 and 3, while the total tephra deposit is associated with a VEI 3 (excluding the volume of the cone).
40Ar/39Ar dating of the Malwa Plateau subprovince, Deccan Traps, India
Authors: Tholt Andrew , Renne Paul , Vanderkluysen Loÿc , Pande Kanchan , Mohabey Dhananjay , Dhobale Anup
Published: March 2022

Our systematic study of the spatial-temporal evolution of magmatism in the Deccan Traps   Large Igneous Province provides new data from the Malwa Plateau(MP) subprovince, which lies north of the comparatively well-studied Western Ghats. 40Ar/39Ar analysis was performed by incremental laser heating of multigrained plagioclase aliquots, in multiple (typically 4) experiments per sample.  Achievable precision is strongly anticorrelated with Ca/K of the plagioclase, reaching ~0.1% (pooled plateau ages, 1 s.d. intralaboratory precision) for some samples with Ca/K< 80. Results have been obtained from samples between ~100-800 m elevation, spanning virtually the entire exposed stratigraphy of the MP. Most of the MP overlaps in age with the older Kalsubai and Lonavala subgroups (~66.3 to 66.0 Ma) of the Western Ghats(WG), but MP basalts do not align with traditional WG chemical stratigraphy suggesting multiple contemporaneous eruptive centers and magma systems. The lowest (134 masl) lava dated is 66.8 ±0.07 Ma, significantly older than anything yet dated in the WG but identical to the result of Schöbel et al. (2014) for a stratigraphically low lava elsewhere in the MP. This is consistent with the consensus that the inception of volcanism progressed generally from North to South. Collectively, our data indicate a much slower mean lava accumulation rate for the basal MP, increasing sharply from 66.4 to 66.2 Ma and slowing by the Cretaceous-Paleogene boundary (KPB). MP lava accumulation rates decrease around the time of the KPB coincident with when eruption rates are inferred to increase in the WG. At similar elevations, our results overlap with the age model presented by Eddy et al. (2020) based on U/Pb dating of zircons from presumed silicic ashes preserved in red boles between lava flows, however our data span about twice their elevation range encompassing the lower portions of the section where we obtained the oldest ages. Our results indicate that the peak lava extrusion in the MP coincided closely with the Late Maastrichtian Warming Event (Barnet et al., 2017).
Analysis of the 2021 March 27th Mw 5.2 earthquake sequence in the Adriatic Sea using new workflows for offshore seismicity monitoring
Authors: Grigoli Francesco , Mazzotti Alfredo , Molinari Irene , Stucchi Eusebio , Tognarelli Andrea , Aleardi Mattia , Stipcevic Josip
Published: March 2022

On 2021 March 27th an Mw 5.2 earthquake occurred in the Adriatic Sea, between the Italia and Croatian coast. The earthquake sequence lasted for several months and consisted of more than 150 seismic events with a magnitude above 2. Analyzing offshore seismic sequences is challenging both for the lack of optimal seismic monitoring networks and detailed enough velocity models. These conditions strongly limit the data analysis procedures, leading to inaccurate results that may have severe effects on the identification of the seismogenic structure associated with the seismic sequence, bringing to wrong seismo-tectonic interpretations, with direct consequences in the seismic hazard assessment of an area. In this study, we analyze the March 2021 Mw 5.2 earthquake sequence that occurred in the Adriatic Sea with recently developed location techniques. Our workflow allows achieving a higher location accuracy, even when dealing with suboptimal monitoring conditions. We analyze this dataset using waveform-based location techniques and a recently developed location technique based on Distance Geometry Solvers (DGS). This last approach uses inter-event distances between earthquake pairs estimated at one or two seismic stations to get high-resolution locations of seismicity clusters. The application of such techniques led to different improvements in locating the seismic sequence, which is more clustered and clearly shows an N-S trending compatible with the geological setting of the area.
Impact of global changes on soil erosion in an Italian basin of mixed pastures (Sicily)
Authors: Marien Laurène , Ciampalini Rossano , Licciardello Feliciana , Giuffrida Emanuela Rita , Pastor Amandine Valérie , Huard Frederic , Raclot Damien
Published: March 2022

Soil is an essential natural resource, non-renewable on a human time scale, which is degraded mainly by water erosion, especially in the Mediterranean context. Erosion can cause significant soil losses at the plot and catchment level through the transfer of sediments which, in a framework of global changes (climate and land use), may severely increase in intensity.

This study was part of the MASCC/Arimnet2 project, which aimed to assess the vulnerability of Mediterranean agricultural soils to global changes and contribute to the definition of sustainable agricultural conservation strategies for Mediterranean agro-ecosystems. In the challenge of reconciling agricultural production, environmental protection and the effects of climate change, we believe that some trade-offs are possible.

We assessed the impact of global change scenarios on soil loss in a mixed pasture watershed in the Cannata basin (Sicily) by 2050, testing strategies to maintain agricultural production and protect soil resources. With the LANDSOIL model, we simulated soil erosion on different climatic (RCP4.5) and land use scenarios derived from a combination of plausible socio-economic conditions. The land use scenarios have been designed according two principal axes: agricultural production and soil conservation. All scenarios tend towards an increase in crops (wheat and orchard) over different degrees represented by the productivity axis. We also adopted a main differentiation between intensive and extensive practices for pasture, and between conventional and conservative practices for wheat and orchard. 

The simulation results show that climate change can lead to a decrease in erosion. The evolution of erosion is also strongly influenced by land use. Environmental protection and sustainability scenarios limit soil erosion compared to the most productive scenarios which, on the contrary, may result in an increase. Reducing intensive grazing in favor of conservation wheat and arboriculture, increases the cultivated area and can decrease soil erosion by 2050 horizon. The use of a suitable land use scenarios can contribute to environmental protection, sustainability, and provide levers to meet food production requirements.

 

Key words

Global change, climate, erosion, land use, modelling, agricultural practices, pasture.
Hyporheic nitrogen removal – assessing the potential for large scale stream restoration in Sweden
Authors: Riml Joakim , Wörman Anders , Morén Ida
Published: March 2022

Biogeochemical reactions along surface water flow paths mitigate nutrient inputs from agricultural land and can have large impacts on both the local water quality and the downstream export of nutrients from agricultural areas. Thus, stream restoration, in terms of engineered structures with the aim to increase the in-stream nutrient retention, is seen as an important strategy to restore the ecosystem functioning of degraded stream systems, mitigate excess nutrient concentrations and reduce the export to downstream recipients. Here, we propose a physically based model framework to assess the large-scale removal of Nitrogen (N) by denitrifications in the hyporheic zone along stream networks. The model framework, supported by an extensive dataset of hydromorphology and reach scale investigations, was used to estimate the current N removal in all local agricultural streams in Sweden defined as having a mean discharge < 1 m3/s and an agricultural N load > 0. Moreover, the theoretical potential to increase this removal by restoration structures that enhances the hyporheic removal efficiency and prolongs the stream residence times was assessed based on the Damköhler number, defined as the ratio between the hyporheic transport time scales and the reaction times scales.

The analyses comprised approximately 26000 stream reaches equivalent to ~75 000 km or 36% of the entire stream network in Sweden and revealed that both the N removal and the conditions limiting the hyporheic denitrification was highly dependent on the stream flow conditions. Specifically, during mean discharge conditions the aggregated results indicated that 13% of the N load to the assessed reaches was removed through hyporheic denitrification and that reaction limited conditions predominately occurred (72% of the assessed reaches). The theoretical potential of N removal, i.e. the N removal under the assumption of optimal hyporheic conditions, during mean discharge conditions was estimated to be 36% when all reaches were aggregated. Overall, the study shows that stream structures, especially if implemented over larger distances, could be a promising restoration strategy to enhance hyporheic removal and reduce terrestrial N export from agricultural areas.
Relationship between surface thermodynamic contrasts and precipitation intensity in idealised monsoon simulations
Authors: Colin Maxime , Haerter Jan O. , Dixit Vishal
Published: March 2022

While the traditional view of monsoons as continental sea breezes generated by land-sea contrasts was shown to have serious limitations, several competing alternative frameworks look promising. Within this debate, it remains unclear if the surface temperature contrast matters at all for the monsoon precipitation, and why there is a non-linear intensification of precipitation intensity with surface temperature forcing.

 

Idealised studies such as aquaplanets often help improve our understanding of basic mechanisms. But there are very few idealised simulation studies of monsoons at high resolution. Therefore, to determine if monsoon non-linearities with surface forcing come from convective processes, dynamical feedbacks, or from non-linearities in the forcing themselves, we devise a modular framework to simulate idealised monsoons at convection-permitting resolution with the WRF model, in a domain based on an aquapatch (mini-aquaplanet), but in which we can gradually add more realistic components, such as an interactive land surface. The model is forced by a season-dependent meridional contrast of surface temperature, with comprehensive physics and rotation. We compare a series of aquapatch experiments with increasingly intense smooth sea surface temperature forcings with another series including land with increasingly sharp surface temperature contrasts at the land-ocean interface.

 

By relating forcing to responses, we aim to describe the non-linearity of the relationship between surface temperature gradient (or surface Moist Static Energy (MSE) gradient, or low-level wind), and precipitation intensity (or monsoonal precipitation surface area, or monsoon onset timing). This should help clarify the actual role that surface temperature and MSE gradients play in controlling monsoon precipitation, and could potentially hint at the effect of climate change on monsoons.
Analysis of snow water equivalent data needs and capabilities
Authors: Vuyovich Carrie , Barros Ana , Hall Dorothy , Kim Rhae Sung , Cho Eunsang , Wrzesien Melissa , Kumar Sujay
Published: March 2022

Global snow cover is an integral part of the Earth’s water and energy cycles, contributing life-giving water resources to billions of people around the world while helping to cool the planet by reflecting solar energy back to space.  Accurate measurements of snow at a regional scale are needed to improve runoff predictions to inform water supply and hydropower needs and to help predict conditions that are associated with floods, drought, and wildfires. Though we can measure the extent of snow cover globally, we cannot yet reliably measure the amount of water stored in a snowpack, or snow-water equivalent (SWE) from space at the resolution and accuracy needed to understand its role in the water cycle. In addition, it is uncertain how the extent and the volume of snow will be changed across the globe in a warmer climate. Here we will review the snow data needs to address our most pressing science questions and operational requirements. We will also present the results of a coverage analysis of SWE data from currently-available and upcoming sensors over the northern hemisphere to identify gaps in current capabilities.
Composition of organic carbon in surface sediments of Chaun Bay (East Siberian Sea) 
Authors: Poltavskaya Natalina , Gershelis Elena , Grinko Andrey , Charkin Alexander , Guseva Natalia , Yaroshchuk Elena , Semiletov Igor
Published: March 2022

The East Siberian Arctic Shelf (ESAS), the world’s widest and shallow continental shelf, plays a crucial role in the climate system of our planet holding huge amounts of organic carbon (OC) in the permafrost deposits which are remobilized upon accelerating permafrost thaw. To get more detailed insights into the sources of OC and compare the mechanisms of its transformation in the different ESAS zones, we investigate a scarcely studied coastal area of the East Siberian Sea – Chaun Bay (CB), a semi-closed accumulative area, where the influence of river discharge is limited and the coastline deposits are composed mainly of the rocky formations, which is contrasting to the permafrost-dominated Arctic bays.

In this study, we analyzed  25 surface sediments collected along the profile from the coastal zone of CB to the midshelf of East Siberian Sea. To characterize the OC composition, we used Rock-Eval indicators along with traditional molecular markers (n-alkanes; n-alkanoic acids). Detailed grain size composition was also performed in order to assess the sedimentation environment operating in the study area.

Sediments are mostly represented by sortable silt (7.61-62.48% on average 43.5%), fine silt (1.98-60.9% on average 34.63%) with a certain proportion of clay (average 11.13%) predominantly in the inner shelf areas, and sand (average 10.73%) deposited in the eastern, southern, and western (Aion Island) parts of the CB.

OC content along the studied profile ranged from 0.49 to 1.76%. Hydrogen index along the studied profile ranged from 111 to 232 mg/g, Oxygen index varied from 134 to 239 mg/g. The relationship between HI and OI indicated roughly equal contributions of terrestrial and marine sources to the OC composition. Meanwhile, variable distribution of n-alkanes is observed with a pronounced presence of high-molecular-weight n-alkanes, which are recognized as higher terrestrial vegetation markers. These data will be further combined with more detailed biomarker analysis to reveal the OM sources proportions in the CB sediments and to understand the dominating mechanisms of OC transformation within this area.

This analytical studies were financially supported by RSF (Project # 21-77-00075).
Explosive Volcanism Drives Bumper North Sea and Grand Banks Fish Catch, 1600-1850 CE
Authors: Ludlow Francis , Matthews John , Pausata Francesco
Published: March 2022

Research that twins data from human (written) archives with data from natural environmental archives represents a rapidly advancing frontier in understanding the ecosystem and linked societal impacts of climatic change. The study of explosive volcanic eruptions, capable of inducing severe short-term climatic anomalies, provides a proving ground in which to develop the methodologies required to combine these disparate sources of evidence, and for showcasing the insights that can be achieved. Volcanic influences on the oceans are becoming increasingly understood, through advances in marine palaeoenvironmental proxies and more sophisticated Earth system modelling. At the same time, growing concern exists over the impacts of present and projected climatic changes on marine ecosystems and important higher trophic level species (Cod, Herring) exploited by commercial fisheries. Here we examine the impact of major explosive volcanism on North Atlantic sea-surface-temperatures (SSTs) using the Norwegian Earth System Model, and on North Sea Herring (1600-1860 CE) and Grand Banks Cod (1675-1827 CE) populations, using rigorously reconstructed catch volumes from contemporary documentation. We show that volcanic eruptions, identifiable through elevated sulfate levels in polar ice cores, impacted ocean temperatures and triggered population booms in both species during the first post-eruption decade. We also show this response to be consistent with expected increases in plankton productivity (a key food source for Cod and Herring) under lower SSTs in the North Sea and higher SSTs in the Grand Banks, respectively. We complement our historical analyses with Cod and Herring population modelling, similarly predicting a population boom in the first decade following a positive ecosystem disturbance (e.g., increased food availability for Cod and Herring, promoting increased survivorship). Lastly, we employ historical Herring price data to examine market responses post-eruption, observing an increase in prices in the first two post-eruption years, thus indicating an increased demand for Herring as a substitute for terrestrial agriculture likely to have been impacted by volcanic climatic anomalies. Our results will help improve fish population projections for the North Atlantic after the next big eruption. This work has been funded by the ERC NorFish (ID 669461) and 4-OCEANS (ID 951649) projects.
A multi-faceted, long-term analysis of Mediterranean heatwaves using in-situ temperature observations, remote sensing imagery and large-scale circulation types.
Authors: Agathangelidis Ilias , Cartalis Constantinos , Tzanis Chris , Kourtesiotis Christos , Philippopoulos Kostas
Published: March 2022

The Mediterranean basin is one of the most thermally vulnerable regions of the planet, already affected by frequent extreme heat events, which are projected to increase in the future. Using multiple extreme climate indices and daily temperature observations from over 50 meteorological stations in the region (NOAA Global Historical Climatology Network daily database) the dates of past heatwave events were identified from 1961 to 2020. While derived heatwave metrics from threshold-based indices generally differed from more complex, calendar day percentile-based indices (e.g., CTX90PCT), findings confirmed a statistically significant positive trend for the frequency, intensity, and duration of heatwave events for the majority of stations (Mann-Kendall test). Next, long-term (years: 2002-2020) daily satellite-derived Land Surface Temperature (LST) from the MODIS Aqua platform was used to compute surface thermal anomalies at the station locations. The dates and the summary metrics of the maximum anomalies were compared to the previously derived air temperature heatwave events to assess the feasibility of using LST estimates as a heatwave proxy for areas with a scarce station network. Finally, a physical understanding of the mechanisms behind heatwave trends for Athens, Greece was attempted through the use of large-scale synoptic data. Daily 500 hPa geopotential height anomalies were computed from ERA5 reanalysis data (1979-2020); then, an automated classification scheme was modified and applied to detect the circulation types for all past heatwave events for this period in Athens. Results indicated an evolving mixture of circulation types through the decades, associated with different intensities and durations of heatwave events.
Applying multi-site bias correction approach preserving inter-site correlation in the north-western Himalayan region
Authors: Samal Nibedita , Jha Sanjeev
Published: March 2022

Due to unavailability of observation data in the north-western Himalayas, reanalysis data is used as an alternative. The reanalysis dataset generally have bias compared to observation data. Hence, different bias correction approaches are used to post-process the data before using it for any hydro-climatic study. Although distribution parameters in the bias correction approaches are adjusted according to observation data, it can modify or misrepresent dependence structure between variables and sites. Ignoring the observed inter-site dependencies in the correction procedure can result in obtaining corrected outputs with mismatched spatial dependence. Hence a multi-site bias correction approach is used with Schaake shuffle approach to reconstruct the inter-site correlation with rank reordering.

 In this study, we apply multivariate bias correction with schaake shuffle approach on 12 observatory stations of north-western Himalayas. The approach is applied on the variables mean temperature, precipitation, downward longwave radiation, downward shortwave radiation, and wind speed obtained from High Asia Reanalysis dataset at 0.25° horizontal resolution. The bias correction is applied using the observation data availed from the Princeton University global meteorological forcings for a time period of 2001 to 2011. The Leave-One-Out-Cross-Validation approach is used to apply the bias correction by leaving one year data for validation on each loop.

The multi-site bias correction applied to all the variables in different seasons shows that it is reducing the inter-station bias considerably for monsoon, winter, and summer seasons. For Post-monsoon season the improvement is not significant. For monsoon season the RMSE, MAE, and Bias percentage is decreasing for all the variables except precipitation. The inter-site correlation is improved after application of multi-site bias correction.
Yield function of the DOSimetry TELescope (DOSTEL) count and dose rates aboard an aircraft
Authors: Romaneehsen Lisa , Burmeister Sönke , Bernd Bernd , Herbst Konstantin , Marquardt Johannes , Senger Christoph , Wallmann Carsten
Published: March 2022

The Earth is continuously exposed to galactic cosmic rays. The flux of these particles is altered by the magnetized solar wind in the heliosphere and the Earth's magnetic field. If cosmic rays hit the atmosphere they can form secondary particles. The total flux measured within the atmosphere depends on the atmospheric density above the observer. Therefore, the ability of a particle to approach an aircraft depends on its energy, the altitude and position of the aircraft. The latter is described by the so-called cut-off rigidity.
The radiation detector of the detector system NAVIDOS (NAVIgation DOSimetry) is the DOSimetry Telescope (DOSTEL) measuring the count and dose rates in two semiconductor detectors. From 2008 to 2011 two instruments were installed in two aircraft. First we corrected the data for pressure variation by normalizing them to one flight level and determined their dependence on the cut-off rigidity by fitting a Dorman function to the observation. The latter was used to compute the yield function, that describes the ratio of incoming primary cosmic rays, approximated by a force field solution, to the measured count and dose rate for a particular instrument. As for neutron monitors the sensitivity increases substantially above a rigidity of about 1 GV.
We received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 870405. 
Methodologies for surface deformations analysis at regional scale
Authors: Fumagalli Micol , Previati Alberto , Rigamonti Serena , Frattini Paolo , Crosta Giovanni B.
Published: March 2022

Analysis of ground deformation is particularly demanding when displacement rates are in the range of some mm/y.  This study integrates different statistical techniques to unravel the spatial and temporal patterns of vertical ground deformation in an alluvial basin. Beyond the identification of critical areas, this is also essential to delineate a conceptual model for the uplift and subsidence mechanisms in complex environments such as a layered aquifer suffering strong piezometric oscillations and land use changes due to human activities.

The study area covers about 4000 km2 in the Lombardy region (N Italy) and includes the Milan metropolitan area and a part of the Po alluvial plain between the Como and Varese lakes. In this study, Sentinel-1A (C-band) PS-InSAR data with an average revisiting time 6 days and an average PS distance of 20 m, processed by TRE-Altamira, were analysed to investigate different movement styles in the study area.

The PS-InSAR data ranges from 2015 to 2020 and reveal a wide gently subsiding area oriented in NW-SE direction (average subsiding rate of nearly -1.5 mm/yr along the line of sight). Principal Component Analysis (PCA) and Independent Component Analysis (ICA) were applied on ground deformation and piezometric time series, showing analogue spatial patterns of the fluctuation styles. Then, from the correlations between the spatial patterns of ground motion, groundwater level changes and geological data, and between the temporal patterns of rainfall and groundwater abstraction rates, the main causes of ground motion were identified and summarized in a conceptual model.

Finally, after reconstructing the aquifer composition and the geo-hydro-mechanical properties, and by implementing the hydraulic stresses from the conceptual model, a hydro-mechanical coupled FEM numerical model was developed. This allowed verifying the hypotheses through the comparison between the simulated ground displacement and the measured one.
A new methodology for Standard Evapotranspiration classification over mesoscale regions: Application and evaluation of SOM over remotely sensed data
Authors: Solis-Aulestia Maria , Pineda Israel , Piispa Elisa , Williams Scott
Published: March 2022

Standard Evapotranspiration (ETo) is an indicator of water losses given by evaporation and plant transpiration. Its quantification is particularly important for irrigation purposes, however in-situ data is not always accessible. This research aims to develop a methodology for Eto ‘weather’ classification through clustering Eto zones over Ecuador using remotely sensed data and an unsupervised learning algorithm. Thus, we obtained climatological variables from the Weather Research and Forecasting model  corresponding to years 2017, 2018, 2019, 2020, 2021. Following, we pre-processed the raw variables into eight parameters for Eto estimation, as in the Penman-Monteith equation, providing the model input variables for each year of study. Hence, we implemented a Self-Organizing Map (SOM) Artificial Neural Network over each dataset to obtain maps representing Eto clustered classes. Moreover, we tested the methodology's repeatability by applying SOM ten different times over each dataset and by applying the modified Cramers’ V-index to quantify the differences between map comparisons. Accordingly, we selected the SOM parameters that produced a Cramer’s V-index > 0.9  and differences between clustered maps < 0.0001. The outcomes of this research contribute to the classification of Eto ‘weather’ in mesoscale regions with future prospects to Eto ‘climate’ classification over larger temporal and spatial resolutions.
LADDIE: a one-Layer Antarctic model for Dynamical Downscaling of Ice-ocean Exchanges
Authors: Lambert Erwin , Jueling Andre , van de Wal Roderik , Holland Paul
Published: March 2022

A major source of uncertainty in future sea-level projections is the ocean-driven basal melt of Antarctic ice shelves. Remote sensing estimates of basal melt shows kilometer-scale features, and ice sheet models require kilometer-scale resolution to realistically resolve ice shelf stability and grounding line migration. Yet 3D numerical ocean models are computationally too heavy to produce melt rates at this resolution. To bridge this resolution gap, we here present the 2D numerical model LADDIE which allows for computationally efficient downscaling of basal melt rates, based on coarse 3D ocean model output. As a test case, we apply the model to downscale basal melt rates of the Crosson-Dotson ice shelf in the fast-melting Amundsen Sea region. Due to the model’s computational efficiency, parameters can be tuned extensively. We have tuned the model to a range of parameters, namely average basal melt, melt in the Kohler West grounding zone, melt along the Dotson Ice Shelf Channel, and the overturning circulation of the cavity waters. These tuning targets are taken from a range of remote sensing products and in situ ocean observations. We show that the model can be tuned to agree with all observations, providing confidence that the model contains the essential physical processes governing basal melt. We propose that (sub-)kilometer resolution basal melt rates can be used to improve the realism of ice sheet models and their simulations of contemporary and future mass loss. Here we show that LADDIE can provide these boundary conditions in a computationally efficient way.
Paleometagenomic network analysis of ancient DNA from Bering Sea sediments to examine past ecological communities
Authors: Dinkel Viktor , Buchwald Stella Zora , Stoof-Leichsenring Kathleen , Hütt Marc-Thorsten , Nürnberg Dirk , Herzschuh Ulrike
Published: March 2022

Understanding marine ecological systems is a challenging task that requires probing of different comparable states and comprehensive time series analysis. In this approach, we analyze sedimentary ancient DNA recovered from marine sediments which function as an extensive archive of past biota, as they conserve snapshots of the ecological community from the time of its DNA deposition. We examine metagenomic shotgun data from 22 samples as a time series ranging 124 kyrs from a probed sediment core recovered from the Shirshov Ridge in the Bering Sea basin to explore the possibilities of paleometagenomic network analyses. Looking at the presence and abundance of different taxa inhabiting the ocean at certain periods and climatic conditions including (1) the last interglacial (Eemian), (2) the last glacial period, and (3) the modern interglacial (Holocene), we reconstruct and analyze ecological networks and inspect how they have changed and adapted over time. Moreover, by developing extensive network analysis methods including species interaction enrichment and comparable simulation models we evaluate the viability of identifying complex connections and relationships between organisms, as well as the influence of reconstructed environmental factors. Our analysis establishes an initial pipeline for paleometagenomic network analyses and enables further research, e.g. network comparison of multiple marine sites to better understand past ecological mechanisms.
A new approach to the formulation of energetically and thermodynamically consistent ocean models and parameterisations
Authors: Tailleux Remi
Published: March 2022

The momentum balance underlying most numerical ocean models is one in which the primary forces driving fluid motions are rotation, the pressure anomaly gradient, and vertical buoyancy forces. While this form of momentum balance has the advantage of simplicity, it does not in itself reveal much about the dynamical control exerted by the near material invariance of potential temperature and salinity, whereby oceanic motions are expected to be preferentially stirred along `neutral’ directions, nor does it reveal much about the possible dynamical controls imposed by energetics constraints. The main aim of this work is to show that it is possible to rewrite the momentum balance in a way that is much more explicit about the role of the preferential directions for lateral stirring as well as about how energetics affect momentum. The new momentum balance is obtained by combining Crocco’s theorem with the theory of available potential energy. Its main properties is that the forces that make it up (save for friction) are all perpendicular or nearly perpendicular to the 3D velocity field. One force is a new form of Nycander’s P vector, which controls the local changes in available potential energy. The directions that it defines coincide with those defined by the standard neutral vector except in the Southern Ocean and Gulf Stream region, where it is hypothesised that neutral rotated diffusion must cause spurious diapycnal mixing. One another force is given by the gradient of a new form of Bernoulli function, which controls the local changes in total energy. As a result, both forces define two different set of neutral directions, one along which lateral stirring leaves the available potential energy unchanged, the other along which lateral stirring leaves the total energy unchanged. The newly obtained momentum balance can be Reynolds averaged, which reveals the role of the eddy kinetic energy, eddy available potential energy, as well as of the variances and co-variances of sub-grid scale variability of temperature and salinity on the momentum balance for resolved motions. More generally, a full energy cycle can be constructed, with exact equations describing the energy exchanges between resolved and unresolved energy reservoirs, that can form the basis for energetically and thermodynamically consistent parameterisations.
Total mercury and fractionation in benthic organisms from Isfjorden, Svalbard
Authors: Korejwo Ewa , Saniewska Dominika , Bełdowski Jacek , Balazy Piotr , Saniewski Michał
Published: March 2022

Polar regions are important in the mercury cycle. In these regions, mercury is readily deposited on the land and sea surface during a springtime Atmospheric Mercury Depletion Event (MADE). Svalbard is a system in transition, it is a region where the effects of global climate change are the most prominent. This area is also interesting because of possible mercury sources, e.g. a complex pattern of surface currents, varying geological bedrock, and recent glaciers melting. Benthic organisms, especially starfish, can be valuable bioindicators of heavy metal contamination. For that reason, in July 2018, selected benthic organisms: algae, brittle star, sea urchins, sea snails, and starfish were collected in Spitsbergen fjord. Two of the sampling stations were located in the Isfjorden, while one was outside the entrance to the fjord. Total mercury (HgTOT) was present in all organisms. The results showed that starfish are the most contaminated with mercury. Total mercury concentrations in these organisms were at least 10 times higher than in other organisms. However, they deal with harmful mercury by transporting it to the carapace. Of all the research material, starfish and sea urchins were the most effective at removing total mercury from their soft tissues (above 60% mercury in their carapace). The obtained results also show that the dominant fractions were the labile factions that are bioavailable to organisms. The largest share of these forms occurred in predatory organisms.