bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea-to-air methane fluxes in heterogeneous shallow-water environments – how should we assess the integrated flux?
Authors: Brüchert Volker , Bisander Thea , Prytherch John
Published: March 2022

Coastal waters with depths less than 40 m contribute at least 90% to the marine methane flux to the atmosphere and these emissions partially offset the carbon burial efficiency of shallow-water inshore environments. Northern high-latitude shallow-water environments have summer productivity on a similar scale to many well-investigated tropical shallow-water ecosystems, but reliable spatial and temporal assessments of methane emissions have been difficult due to the high habitat diversity and the large seasonal variability in temperature and productivity. Here we report on methane fluxes from shallow bays in the archipelago seas of the central Baltic with a focus on both environmental and methodological factors controlling methane emissions for the period August 2020 to May 2021. Three methods were used to determine methane fluxes: floating chambers (FC), eddy covariance (EC), and thin-film boundary layer models (BL). We present 263 repeated FC flux measurements with corresponding BL calculations, and 3013 EC 30-minute flux periods and related these to environmental controlling factors in three different shallow-water ecotypes. The results showed that vegetation density and sediment type were poor predictors for methane fluxes during the period of our study, while eutrophication influences were clearly detectable. Water depth and distance to shore at the scale of <50 meters were not found to be statistically significant when determining methane flux, whereas the day hour of sampling influenced the results. Wind velocity and temperature have commonly been used to predict methane fluxes, but our results showed that wind was only influential for exposed bays and temperature did not appear to have a direct relationship with methane fluxes. The BL method underestimated the gas transfer at low wind speeds and the EC method showed a low signal to noise ratio, with the majority of the methane fluxes below the detection limit. Overall the three methods showed relatively good agreements, but in terms of sensitivity and correlation with environmental factors the FC method was the most suitable method for spatiotemporal scaling of methane fluxes in these complex inshore habitats.
Energy input in the dayside polar cap during IMF By dominated conditions: Summer vs. Winter
Authors: Reistad Jone Peter , Laundal Karl Magnus , Ohma Anders , Hatch Spencer
Published: March 2022

When IMF By is dominant, which is the typical situation, a highly vortical convection pattern is seen inside the dayside polar cap in the summer hemisphere. In the winter hemisphere, however, the convection is mainly from noon to midnight with little vorticity inside the polar cap. Combined with the vastly different ionospheric conductance between summer and winter due to solar EUV irradiance, these differences in convection cause large summer/winter differences in the Birkeland currents in the dayside polar cap. Hence, the joule heating rates will be very different in the dayside polar cap between summer and winter during the IMF By dominant periods, which is typically associated with weak geomagnetic activity inside the auroral oval. This presentation will focus on the hemispheric differences in e.g. joule heating during such conditions, which will be quantified using the newly developed LOcal Mapping of Polar ionospheric Electrodynamics (Lompe) data assimilation technique. The Lompe technique is similar to the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique, but allows the electrodynamics to be described only in a limited region to reflect the observational coverage. The prescribed conductance will be provided from UV imaging of the aurora (in addition to EUV), allowing also the energy from precipitation to be estimated. While existing empirical models [e.g. Weimer 2005, doi:10.1029/2004JA010884] capture some aspects of the hemispheric asymmetries, this presentation will focus on how recent advances in data assimilation techniques allows us to quantify these asymmetries on an event basis, showing how these typical conditions can lead to vastly different energy input into the two hemispheres.
Hamiltonian Monte Carlo Inversion of Surface Wave Dispersion to Evaluate their Potential to Constrain the Density Distribution in the Earth.
Authors: Lanteri Ariane , Gebraad Lars , Zunino Andrea , Fichtner Andreas
Published: March 2022

We present a probabilistic approach to constrain the density distribution in the Earth based on surface wave dispersion. Despite its outstanding importance in studies of the Earth’s thermo-chemical state and dynamics, 3D density variations remain poorly known, thereby posing one of the major challenges in geophysics.

Since the sensitivity of most seismic data to density is small compared to sensitivity with respect to seismic velocities, regularisation in traditional deterministic inversion tends to bias the recovered density image significantly. To avoid this issue, we propose to solve a regularisation-free Bayesian inference problem using the Hamiltonian Monte Carlo Markov Chain algorithm.

In the interest of simplicity, we consider anisotropic stratified media, where dispersion curves and corresponding sensitivity kernels can be computed semi-analytically. Exploiting derivative information for efficient sampling, Hamiltonian Monte Carlo approximates the posterior probability density of all model parameters, namely the P-wave velocities vPV and vPH , the S-wave velocities vSV and vSH , the anisotropy parameter η, and, of course, density ρ.

The proposed method forms the foundation of an open-source tool box that can be used to assess the unbiased ability of surface wave dispersion data, characterised in terms of frequency and modal content, to constrain density variations and their trade-offs with other Earth model parameters.
Detrital garnet Lu-Hf and U-Pb geochronometry coupled with compositional analysis: Possibilities and limitations as a sediment provenance indicator
Authors: Mark Chris , Stutenbecker Laura , Andò Sergio , Barbarano Marta , O'Sullivan Gary , Glorie Stijn , Simpson Alexander , Daly J. Stephen
Published: March 2022

Detrital geochronology is a powerful tool to interrogate the sedimentary archive of (paleo-)hinterland tectonic, metamorphic, and climatic processes, and can also be applied to modern river sediment as a first-pass tool to establish regional bedrock ages. The popular zircon U-Pb detrital geochronometer has seen widespread adoption for these tasks (3,626/4,471 results for the search term detrital geochronology also contain the term zircon U-Pb; Clarivate Analytics Web of Science). However, zircon fertility is strongly biased to intermediate to felsic source rocks. Moreover, zircon crystallization is volumetrically limited in metamorphic terranes which do not achieve anataxis (e.g., Moecher & Samson, 2006), and is typically restricted to rim overgrowths which are vulnerable to mechanical destruction during fluvial transport, and which are challenging to detect and analyse (e.g., Campbell et al., 2005).

Therefore, it is desirable to develop complementary provenance tools for metamorphic settings. Garnet group minerals are rock-forming in several common metamorphic lithologies, and garnet is therefore a common constituent of clastic detritus from orogens. Moreover, single-grain in-situ dating of garnet by LA-ICPMS is possible using the U-Pb (e.g., Seman et al., 2017) and, by use of an online reaction cell, the Lu-Hf radioisotope systems (Simpson et al., 2021).    

Here, we present results from U-Pb and Lu-Hf double-dating, acquired by LA-ICPMS for detrital garnet recovered from the Oligo-Miocene pro-foreland basin of the European Alps, as well as modern Alpine river sediment. We integrate these data with compositional data acquired by Raman spectroscopy, and energy and wavelength-dispersive X-ray spectroscopy (Stutenbecker et al., 2019). We discuss the implications for Alpine tectonics and metamorphism, and future scope of detrital garnet geochronometry.   

Campbell, I., et al., 2005. Earth Planet. Sci. Lett. 237, 402-432,  doi: 10.1016/j.epsl.2005.06.043

Moecher, D., & Samson, S., 2006, Earth Planet. Sci. Lett. 247, 252–266, doi: 10.1016/j.epsl.2006.04.035

Seman, S., et al., 2017. Chem. Geol. 460, 106–116. doi: 10.1016/j.chemgeo.2017.04.020

Simpson, A., et al., 2021. Chem. Geol. 577, 120299. doi: 10.1016/j.chemgeo.2021.120299

Stutenbecker, L., et al., 2019, Solid Earth 10, 1581–1595, doi: 10.5194/se-10-1581-2019
Hand-written letters and polaroid photo albums linking geoscientists with school classes.
Authors: Stiller-Reeve Mathew , Panieri Giuliana , Argentino Claudio , Waghorn Kate , Vadakkepuliyambatta Sunil , Kalenitchenko Dimitri
Published: March 2022

 

Do we miss something about «traditional” media such as handwritten letters and photography before the digital age? Some of the authors remember this age fondly, and we wanted to see if this fondness could be translated into a science dialogue project with school classes.

We designed and carried out a communication process with 4 classes at different schools across Europe. During this process, each class would interact with a single scientist primarily via hand-written questions & letters, and a Polaroid photo album. The scientists would make this unique, one-of-a-kind album whilst on board a research expedition in the Barents Sea. We asked the question whether this process might show any benefits to the school students involved.

To answer this, we asked the students to write up their thoughts on communicating with a scientist in this way. We analysed the texts and found that most students thought the letters and polaroid albums were a “beautiful experience”. Others commented on how important it is to actually put pen to paper and write, since they use (almost) only digital media these days. Most importantly, the students learnt different elements of the science connected to the research expedition, but also about the scientific process in general. And, equally important, some of the students were surprised and thankful that the scientists took the time to communicate with them in such a personal way.

These results could possibly have been achieved using other media, however the hand-written letters and Polaroids seemed to work very well. They also seemed to conjure up some of the personal memories that we have about communication not so long ago. Maybe there is something to be said for slowing things down with our science communication projects and making them more personal and unique. This is something that snail-mail and making photo albums forces us to do.
Carbon sequestration potential of Miscanthus application as biofuel source in Sweden
Authors: Mohammadi Ali
Published: March 2022

Abstract

Sweden aims to achieve net zero GHG emissions by 2045. To do this, one strategy could be increasing the biomass contribution in energy sector as approximately 75% of total greenhouse gas (GHG) emissions are related to energy consumption. Therefore, it is beneficial to explore efficient ways to upgrade biomass materials into high value-added bioenergy. This study considers the potential of Miscanthus cultivation and its application as biofuel materials in Sweden in terms of carbon sequestration and contribution in climate impact mitigation. Miscanthus, as an energy crop with relatively low maintenance requirements and a high dry matter yield and energy content, can play a major role in the sustainable development of biofuels. Using Miscanthus for energy, results in avoiding fossil fuel combustion and the corresponding GHG emissions. The results of this assessment demonstrated that the Miscanthus cultivation contributes in soil organic carbon sequestration by over one tonne carbon ha−1 yr−1 which results in mitigating a significant amount of soil CO2 fluxes. Therefore, the adaption of Miscanthus biomass, would directly contribute in UN Goal 7, affordable and clean energy, and Goal 13, climate action due to a significant reduction in GHG emissions. The integration of Miscanthus plant into the landscape may stimulate the economy of rural areas in the country and offer more profit than afforestation and reforestation on abandoned and marginal croplands.

Keywords: Energy crops, Climate change, Bioenergy, Soil organic carbon, Ecosystem services
Drivers of the evolution and amplitude of African Humid Periods
Authors: Menviel Laurie , Govin Aline , Avenas Arthur , Meissner Katrin , Grant Katharine , Tzedakis Polychronis
Published: March 2022

During orbital precession minima, the Sahara was humid and more vegetated. Uncertainties remain over the climatic processes controlling the initiation, demise and amplitude of these African Humid Periods (AHPs). Here we study these processes using a series of transient simulations of the penultimate deglaciation and Last Interglacial period performed with an Earth system model of intermediate complexity (LOVECLIM). These results are compared to a transient simulation of the last deglaciation and Holocene. We find that the strengthening of the Atlantic Meridional Overturning Circulation (AMOC) at the end of deglacial millennial-scale events exerts a dominant control on the abrupt initiation of AHPs, as the AMOC modulates the position of the Intertropical Convergence Zone. In addition, residual Northern Hemispheric ice-sheets can delay the peak of the AHPs. Through its impact on Northern Hemispheric ice-sheets disintegration and thus AMOC, the larger rate of insolation increase during the penultimate compared to the last deglaciation can explain the earlier and more abrupt onset of the AHP during the Last Interglacial period. Finally, we show that the mean climate state modulates precipitation variability, with higher variability under wetter background conditions.
Detecting soil water distribution in subsurface irrigated tomato crops by coupling electrical resistivity imaging, 2D Hydrus modeling and proximal sensing techniques
Authors: Raij Hoffman Iael , Vanella Daniela , Ramirez Cuesta Juan Miguel , Lennon William , Harter Thomas , Kisekka Isaya
Published: March 2022

Nowadays there is an increasing need to improve the irrigation and fertilizer efficiency of processing tomatoes in California’s Central Valley, because they represent a major crop in this area. For agronomical and research purposes, agricultural soils are generally monitored and sampled before, during and after the season in order to establish water and fertilizer balances. However, sub-surface drip irrigation and fertigation techniques increase the already heterogeneous water and nutrient distribution in the soil, making representative measurements a challenge. In addition, the crop water status is a proxy that needs to be assessed for evaluating the response of the crop to water management.

In this study, we coupled multiple methodologies, including electrical resistivity imaging, 2D Hydrus modeling and proximal sensing techniques, for detecting the soil water redistribution, and characterizing the relative crop water status, in a sub-surface drip irrigated processing tomato field. Specifically, soil electrical resistivity was measured by electrical resistivity tomography (ERT) in two transects during an irrigation event in parallel and perpendicular to the subsurface drip irrigation line. The time-lapse ERT transects were compared to matching 2D-HYDRUS hydrological models and the relative differences were explained by local heterogeneities in electrical resistivity and water content changes. Water contents, measured with neutron probe and TDR techniques, were compared to the changes in resistivity during the irrigation event and the heterogeneity in the different root-zone locations described. In addition, surface temperature measured using infrared thermal thermometer (IRT) showed correlations with the ERT soil resistivity changes.

In this study, a combination between multi-dimensional soil modeling and minimally invasive techniques (geophysical and IRT) has provided specific information on local water distribution and its interaction with root water uptake. This analysis will be used to enrich TDR-measured water contents and 2D modeling of root zone soil water dynamics of processing tomatoes during the rest of the season when spatially distributed ERT data is not available.
The Pyxis project: a sounding rocket developed by Skyward Experimental Rocketry from Politecnico di Milano in collaboration with the Scientific High School “Cigna-Baruffi-Garelli” – Mondovì
Authors: Tealdi Paolo , Battocchio Luciano , Innocenti Fabrizio , Aimo Giovanni (John) , Corallo Federico , Donghi Nicolò , Colombo Matteo , Florio Nicolò , Nidasio Alberto , Del Duca Alessandro , Rosato Davide , Cucchi Lorenzo , Ciuti Lorenzo , Porro Virginia
Published: March 2022

The Pyxis project is a sounding rocket developed by Skyward Experimental Rocketry from Politecnico di Milano, with the ultimate goal of participating in the European Rocketry Challenge in October 2022. The rocket, which will be the most advanced Italian sounding rocket ever developed by university students, will give the opportunity to hold a payload of 1U inside the nosecone. After lift-off, the rocket will rapidly reach the apogee at 3000 meters, where the nosecone with the payload bay will be ejected and recovered independently from the rocket thanks to an autonomous guided parafoil. For the payload development the team is collaborating with the students at the Scientific High School “Cigna-Baruffi-Garelli” – Mondovì, as they are creating a sensing platform, through the use of Blebricks sensors (IoT sensors), capable of detecting enviromental data such as pressure, temperature and quality of the air, storing it on board for post-flight analysis. 
The students at “Cigna-Baruffi-Garelli” are already involved also in another STEM experience with hot air/stratospheric balloons called infoBalloons, presented last year at EGU 2021 (Tealdi, P., Innocenti, F., and Aimo, G. (.: infoBalloons: an Italian High School educational self-made budget friendly STEM experience with hot air/stratospheric balloons, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13420, https://doi.org/10.5194/egusphere-egu21-13420, 2021). infoBalloons 2.0 is a selected Sounding Balloon (SB) Experiments in the 2nd HEMERA Call for Proposals (HEMERA H2020. This project has received funding from the European Union's Horizon 2020 research and Innovation programme under grant agreement No 730970).
An added value in the Pyxis project is the participation as partners of LB Space with Luciano Battocchio (retired Space Engineer - Exomars Parachute Program Manager), Bleb Technology with Fabrizio Innocenti (CEO),  John Aimo Balloons with Giovanni (John) Aimo. 

 
Remediation of pentachlorophenol contaminated forest soil by the combined action of biostimulation and bioaugmentation techniques
Authors: Di Rauso Simeone Giuseppe , Werheni Ammeri Rim , Hidiri Yassine , Salah Abassi Mohamed , Mehri Ines , Costa Sara , Hassen Abdennaceur , Rao Maria
Published: March 2022

Pentachlorophenol (PCP) is a recalcitrant compound that could persist in the environment causing serious pollution concerns. Bioremediation of PCP is demonstrating to achieve encouraging results compared to the common physical and chemical techniques.

The aim of this work was to assess different bioremediation processes as biostimulation and/or bioaugmentation approaches of artificially PCP (100 mg kg-1) contaminated forest soil (Sc). The biostimulation treatment provided phosphate and three different organic amendments, such as forest compost (FC), municipal solid waste compost (MC) or sewage sludge (SS). Two different microbial consortia B1 and B2 were used as bioaugmentation treatments. The combination of both biostimulation and bioaugmentation techniques was also assessed. Soil physical and chemical properties, PCP amount, soil microbial biomass carbon, soil respiration and some enzymatic activities at zero time (T0) and after 30 d incubation (T30) were evaluated.

No significant changes in terms of main chemical soil properties were observed, but an increment of organic carbon in all organic amendment-based treatments at T0 and T30 was observed. The PCP concentration at T0 was on average 82 mg kg-1 in all soil samples. After 30 days natural attenuation was responsible for the reduced PCP extractable in Sc (68.5 mg kg-1). The combined action of biostimulation and bioaugmentation led to a strong PCP reduction (71%) in Sc+B1+FC sample, whereas a depletion of only 52% and 41% occurred with the single application of FC or B1, respectively. The presence of PCP negatively affected soil microbial biomass carbon and the activity of dehydrogenase and fluorescein diacetate hydrolysis that recovered upon organic amendment also combined with microbial consortia B1 or B2. FC based biostimulation treatment also stimulated soil respiration. These results demonstrate that the simultaneous treatment of biostimulation and bioaugmentation showed a better performance in the PCP removal with more effectiveness than the single techniques.
Interrogating the volume of the East Irish Sea sedimentary basins using probabilistic tomographic results
Authors: Zhao Xuebin , Curtis Andrew , Zhang Xin
Published: March 2022

The ultimate goal of a scientific investigation is usually to find answers to specific questions: what is the size of a subsurface body? Does a hypothesised subsurface feature exist? Which competing model is most consistent with observations? The answers to these and many other questions are low-dimensional, yet must often be inferred from high-dimensional models and data. To address the questions, existing information is reviewed, an experiment is designed and performed to acquire new data, and the most likely answer is estimated. Typically the answer is interpreted from geological and geophysical data or models, but is biased because only one particular forward function (model-data relationship) is considered, one inversion method is applied, and because human interpretation is a biased process. Interrogation theory provides a systematic way to answer specific questions using statistically unbiased estimators. It combines forward, design, inverse and decision theory, and focuses them to maximise information on the space of possible answers.

This study estimates the volume of the East Irish Sea sedimentary basins in the UK using 3D shear wave speed models derived from surface wave dispersion inversions. In order to answer volume-related questions, it is first necessary to define a target function that translates any (high-dimensional) model into (1-dimensional) volumes of interest. A key revelation of this study is that while the majority of computation may be spent solving inverse problems probabilistically, much of the skill and human effort involved in answering real-world questions may be spent defining and calculating those target function values in a clear and unbiased manner.
Utilizing Cosmic Ray data as input for neutron-based soil moisture measurement
Authors: Giese Hanna , Heber Bernd , Herbst Konstantin , Schrön Martin
Published: March 2022

Neutrons on Earth interact with the soil and are substantially moderated by hydrogen atoms. Since the reflected neutron flux is a function of the soil water content, cosmic-ray neutron measurements above the ground can be used to estimate the average field soil moisture. Thus, if the local incoming neutron flux and the abundance of nearby hydrogen pools are known, the reflected neutron flux could be modeled and compared to observed detector count rates. However, the incoming neutrons are secondaries produced by interacting energetic Galactic Cosmic Rays (GCRs) in the atmosphere. The total neutron flux on the ground depends on the solar modulation-dependent GCR flux, the geomagnetic position, and the altitude within the atmosphere. So far, measurements of either the Jungfraujoch neutron monitor (NM) or a NM of similar cutoff rigidity have been used and altered to estimate the neutron flux at the position of each neutron detector. In this contribution we present a new method based on the Dorman function to directly compute the local neutron flux using remote neutron monitor data.

We received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 870405
Paleomagnetism of the Guaymas Basin, Gulf of California: New Results from IODP Expedition 385
Authors: Koornneef Louise M.T. , Kars Myriam A.C. , Morris Antony ,   Expedition 385 Scientists
Published: March 2022

Sill-driven hydrothermal circulation results in geochemical exchanges between ocean crust, sediments, and seawater. IODP Expedition 385 drilled sill/sediment sequences at eight sites in the Guaymas Basin to better understand the interactions between magmatic, hydrothermal, and sedimentary systems in a highly active marine environment.

We focus on the magnetic data of two adjacent sites with similar sedimentation history, but different alteration degree due to an intruding sill. Site U1546 recovered a 540m sedimentary sequence disrupted by an 80m wide sill between 350/430 meters below seafloor (mbsf). The sill terminates towards Site U1545 which recovered 507m of an undisrupted sedimentary sequence. These sites allow us to directly compare paleomagnetic measurements and changes related to the different heat system in both sites.

Detailed paleomagnetic measurements were conducted, including anisotropy of magnetic susceptibility (AMS), thermal demagnetization, and alternating field demagnetization on both discrete samples and section halves. Both sites feature a decrease of magnetic intensity (NRM) and magnetic susceptibility between 50-80 mbsf, associated with a change in coercivity (averaging from 24 to 10 mT from MDF). This correlates with the sulphate-methane transition zone (SMTZ) where magnetic mineral assemblages change because of biogeochemical processes. A stable magnetic component was identified in most samples after removal of a low coercivity magnetic drilling overprint (generally removed after AF 5-10 mT), resulting in a mean inclination of ~46°, close to the geocentric axial dipole (GAD) inclination of 46.3°. Cores were assigned to the C1n Brunhes chron.  In sill-bearing Site U1546, magnetic intensity is found to gradually increase toward the sill and to decrease below the mafic sill (basaltic, doleritic, and gabbroic textures), suggesting authigenesis of magnetic minerals in the contact zone, likely triggered by the heat of the igneous intrusion in combination with hydrothermal fluid circulation.

Here we will present an overview of the paleomagnetic and rock magnetic data used to identify the magnetic mineralogy through the oceanic crustal sections of the Guaymas Basin, and to compare these two adjacent sites to assess the effect of heat and hydrothermal circulation on the paleomagnetic record in the Guaymas Basin.
Tsunami hazard along the Alboran Coast triggered by submarine landslides
Authors: Rabaute Alain , Lafuerza Sara , Thomas Maud , Sainte-Marie Jacques , El Baz Apolline , Mangeney Anne , d'Acremont Elia , Basquin Elise , Mercier Denis , Creach Axel , Gorini Christian
Published: March 2022

Historical earthquake records suggest that the Alboran Sea seismicity is mostly triggered by strike-slip faults with little or no vertical throw preventing significant tsunami formation. Although in the North Alboran Sea the Averroes fault may have a tsunamigenic potential, the main active fault system responsible of the last three major earthquakes (Mw ≥ 6) in the South Alboran Sea, the Al-Idrissi fault, has no significant vertical component. This points to submarine landslides as the main potential source of tsunamis for the southern sector of the basin. Our study deals with the tsunamigenic potential of submarine landslides in the southern Alboran Sea, where several deposits are stacked within the last million year of sedimentary cover. We have identified up to 67 landslide events with volumes between 0.01 to 15 km3. The probability of landslide occurrence has been analysed with a logistic regression describing the relationship between a binary response variable (existence or absence of landslide) and a set of predictor variables such as high seafloor gradients and presence of active faults. The analysis of the severity of a given landslide has been investigated based on the estimation of the probability that the landslide reaches a certain (high) level (e.g. tsunami run-up or submarine cable breaks) giving that it has occurred through the extreme value analysis. We have used the Shaltop code simulating landslide run-out on the basis of a depth-averaged model based on the hydrostatic Saint Venant equations and Coulomb-type basal friction considering a Bingham rheology. Our tsunami simulations include Shaltop output scenarios as a source of the generated tsunami through hydrodynamic simulations using the hydrostatic 3D Navier-Stokes code Freshkiss3d. We found that tsunamis waves triggered by submarine landslides on the South Alboran Sea would be no higher than two meters. However, the tsunami would include wavelengths of tens of kilometres translating into important water volumes flooding several areas of around the Alboran coast. 
The problem of signal loss for the upcoming Beyond EPICA Little Dome C (BELDC) ice core.
Authors: Gkinis Vasileios , Laepple Thomas , Malegiannaki Eirini , Shaw Fyntan
Published: March 2022

The recently commenced drilling operation at the Beyond EPICA Little Dome C (BELDC) site will attempt to recover an ice core that reaches back to 1.5 Ma, a time during which the enigmatic Mid-Pleistocene Transition (MPT) took place. While the ice flow and heat flux regime at the drilling site will largely determine the age, as well as the nominal temporal resolution of the deeper parts of the BELDC core, molecular diffusion in solid ice will play a significant role in the effective temporal resolution of the δ18O signal. Here we look into the expected diffusion characteristics of the BELDC ice core by firstly addressing a previously reported problem, that of the δ18O signal loss in the deeper parts of the Dome-C ice core, particularly over Marine Isotope Stage 19 (MIS-19). By using isotope diffusion modelling in combination with high resolution δ18O data, we show the importance of the ice flow thinning function for the estimation of the diffusion length. We also comment on the large uncertainty imposed by the poor knowledge of the diffusivity coefficient. Based on recently published results on the dating of the BELDC site we provide a first order estimate of the effective resolution of the δ18O signal over the MPT transition.
A Satellite-based analysis of Tiber River inland-marine water connectivity
Authors: Belloni Rossella , Pitarch Jaime , Adduce Claudia , Tarpanelli Angelica , Falcini Federico
Published: March 2022

Connectivity describes the efficiency of material transfer between the components of a system. The definition of these components varies among different disciplines and in relation to the material under consideration.

River systems are complex and dynamic environments where multiple and highly inter-correlated processes occur at various spatial and temporal scales. Because of this reason, in-situ traditional techniques for inland waters monitoring are often inadequate to the full understanding of river processes, making the evaluation of river system and inland-marine water connectivity a challenging task.

In this study, we use high-resolution multispectral satellite data acquired by the Sentinel-2 Earth observation mission of the EU Copernicus Programme to investigate the connectivity of the lower Tiber River basin (Italy) from a sedimentological and biogeochemical point of view. To this end, Level-1C satellite imagery, collected on the study area for the period 2017-2020, were processed through the ACOLITE software to perform image atmospheric correction and to obtain water turbidity (WT) and chlorophyll-a (Chl) concentration values on multiple regions of interest along the river course up to the river mouth and the adjacent coastal area. WT and Chl are indeed key parameters for both sediment transport and water quality monitoring of inland and coastal waters. River connectivity was then evaluated by analyzing the spatio-temporal variability of seasonal climatologies of the satellite-derived parameters.

The analysis showed a significant dependence of suspended sediment transport and chlorophyll concentration on hydrological conditions; however, complex dynamics arises. From a sedimentological point of view, as expected, connectivity seems to be positively correlated with the magnitude of the hydrological events, with the highest and lowest degrees of connectivity of WT during the highest and lowest discharge events respectively (winter and summer). From a biogeochemical point of view, there seems to be an optimum window during moderate hydrological conditions (spring) that, on one hand, allow for sediment resuspension and, therefore, nutrients transport along the river course, but on the other, prevent to reach critical resuspension values that would reduce and/or hinder Chl concentration along the river course.
Climate feedback from vegetation emissions strongly dependent on modelling of atmospheric chemistry.
Authors: Weber James , Archer-Nicholls Scott , Abraham N. Luke , Shin Youngsub Matthew , Griffiths Paul , Grosvenor Daniel P. , Scott Catherine E. , Archibald Alex T.
Published: March 2022

Emissions of volatile organic compounds from vegetation (BVOCs) affect climate via changes to O3, CH4, aerosol and clouds. BVOC emissions themselves exhibit dependencies on climate (causing a feedback) and land use change including certain climate change mitigation strategies. Therefore, emissions are predicted to change under future climate pathways yet there remains considerable uncertainty between climate models in the sign and magnitude of the net climatic impact BVOCs (Thornhill et al., 2021). 

One contributor is uncertainty in the description of BVOC chemistry, hitherto minimally assessed in a climate context despite recent scientific advances. In the climate model UKESM1 we evaluate the influence of chemistry by comparing the response to a doubling of BVOC emissions in a pre-industrial (PI) atmosphere using standard and state-of-the-art chemistry mechanisms, the latter featuring recent improvements in chemical understanding. The feedback is positive in both mechanisms with the negative feedback from enhanced aerosol scattering outweighed by positive feedbacks from O3 and CH4 increases and aerosol-cloud interactions (ACI). We suggest the ACI response, contrary to past studies, is probably driven by reductions in cloud droplet number concentration (CDNC) via suppression of gas phase SO2 oxidation. 

The net feedback is 43% smaller with state-of-the-art chemistry due to lower oxidant depletion which yields smaller increases in CH4 and smaller decreases in CDNC. Thus, the PI climate in UKESM1 is only about half as sensitive to a change in BVOC emissions with state-of-the-art chemistry, highlighting the important influence of simulated chemistry.  

The role of chemistry is also compared to the inter-model variation in BVOC forcing. We suggest the variation in chemistry between models is likely to play a large role in explaining the variation in the BVOC feedback from O3 and CH4 changes and a smaller role in the aerosol feedback, highlighting the need to improve the descriptions of BVOC chemistry and BVOC-aerosol coupling in tandem to improve assessments of the climatic impact of future BVOC emission changes.

 

 
Aerosol impacts for convective parameterizations: Applications of the Grell-Freitas Convective Parameterization
Authors: Barnes Hannah , Grell Georg , Freitas Saulo
Published: March 2022

The Grell-Freitas (GF) cumulus parameterization is an aerosol-aware, scale-aware convective parameterization that has been used globally and regionally. This presentation will focus on one of the several developmental activities ongoing in GF: the continued development of its aerosol-aware capabilities and the impact on global forecast models. While it is well established that aerosols impact weather and climate, relatively little work has been done to represent their impact in medium-range forecasts and in convective parameterizations.

GF includes three aerosol related cloud processes: aerosol-influenced auto-conversion of cloud water to rain water, aerosol dependent precipitation efficiency, and aerosol wet scavenging based on memory and precipitation efficiency. Additionally, if aerosols are based on analysis or climatologies, they are allowed to slowly return to their original concentrations during precipitation-free periods.

In its most simplistic approach, aerosol pollution in GF is characterized using aerosol-optical depth (AOD). The method of our application is extremely efficient and can be adapted to use different aerosol or AOD products.  For example, other products that could be used include the aerosol climatology used by the Thompson Aerosol-Aware Microphysical Parameterization or predicted aerosols using NOAA’s aerosol prediction model, which is currently one ensemble in the Global Ensemble Forecast System – Aerosols (GEFS-Aerosols). The treatment of aerosols in GF should be most sensitive in regions with either very high or very low levels of pollution.

The impact of these changes to GF will be shown in a version of NOAA’s experimental global prediction model, with 
Measurement and modeling of small-scale to mesoscale ocean circulation in the Straits of Florida
Authors: Vanderplow Breanna , Kluge John , Soloviev Alexander , Dodge Richard , Wood Jon , Evans Johanna , Venezia William , Ferrar Michael
Published: March 2022

Predicting ocean circulation in strong currents remains challenging because of limits in modelling capabilities such as resolution. Coastal ocean circulation models typically have horizontal resolution starting from 1 km. To address this matter, we have developed a high resolution three-dimensional computational fluid dynamics (CFD) model for strong ocean currents such as the Gulf Stream. Our model domain contains three inlets and an outlet and has been verified with field data from the Straits of Florida. For model verification, a 6 ADCP mooring array in a rectangular shape was deployed 8 miles offshore on the Miami Terrace. The data from 5 ADCP moorings were used to produce the inlet boundary conditions, which were updated every 1 minute. The sixth ADCP in the center of the outlet was used for model verification. This approach has demonstrated good predictive ability for ocean circulation in the challenging environment of a strong western boundary current. We anticipate our work to be a starting point for the development of sophisticated prediction models applicable to western boundary currents in the range from small-scales to sub-mesoscales, based on advanced data assimilation techniques.
A new conceptual picture of the transition layer
Authors: Albright Anna Lea , Bony Sandrine , Stevens Bjorn , Vogel Raphaela
Published: March 2022

The transition layer in the trades has long been observed and simulated, but its origins remain little investigated. It is often associated with an about 150 m deep layer at the top of the subcloud layer that acts as a barrier to overlying convection. Using extensive observations from the EUREC4A field campaign, we propose a reconceptualization of the transition layer. Strong jumps at the mixed layer top, as expected from the theory of cloud-free convective boundary layers, are only found rarely and when they occur, they tend to occur in large cloud-free areas. We show that small clouds with their bases around 600 m maintain the transition layer, in analogy with the maintenance of the trade-wind inversion by deeper clouds. From this analysis also emerges the potential for an alternate view of entrainment mixing, which is based on the ability to detrain condensate into the transition layer and induce gentle sinking motion through negative buoyancy. Mixed layer theory and Paluch mixing diagrams are also used to gain inferences into entrainment mixing.
Electron earthward transport in the Earth magnetotail: adiabatic convection heating and magnetic curvature scattering
Authors: Shustov Pavel , Artemyev Anton , Petrukovich Anatoliy
Published: March 2022

The near-Earth electron population is largely formed by earthward electron transport from the middle and distant magnetotail. Such transport is associated by electron adiabatic heating by the convection electric field. Although the adiabatic heating models predict formation of strongly anisotropic electron populations, spacecraft observations show that hot electrons are well isotropic in the near-Earth magnetotail. One of the possible isotropisation mechanisms is the electron scattering by magnetic field line curvature in the magnetotail current sheet with the stretched magnetic field line configuration.  In this presentation we show model results of electron transport and curvature scattering for slow magnetosphere convection. Our model combines the canonical theory of the electron guiding center motion and the mapping technique of electron pitch-angle scattering. We show formation of electron spectra typical for the near-Earth magnetotail and estimate the contribution of the curvature scattering to electron losses.
La Niña Came to Eden
Authors: McPhaden Michael J. , Karamperidou Christina
Published: March 2022

In 1929, Dr Friedrich Ritter and his mistress Dore Strauch left their spouses and the turmoil of post-World War I Germany for the remote, rugged and uninhabited volcanic island of Floreana in the Galapagos archipelago.  Their dream was to live self-sufficiently in an idyllic tropical setting unspoiled by civilization. Yachts stopping at Floreana after Ritter and Strauch established a homestead reported on their pioneering enterprise to the outside world in the early 1930s. The news created a sensation that subsequently attracted other settlers to the island, one of whom, a mysterious Austrian faux baroness, vexed Ritter and Strauch to the point of open hostility. Not all the participants in this drama survived the experience of colonizing Floreana though. A prolonged drought that gripped the island from 1933 to 1935 led to food shortages and ultimately the death of Dr. Ritter, who unwittingly ate tainted chicken out of desperation. The bizarre intrigues, extraordinary adventures, and struggles to endure on Floreana were chronicled in Strauch’s 1936 memoir “Satan Came to Eden” and a 2013 Hollywood documentary based on it.  A story that has not been told is how climate variability, and in particular an extended period of cold La Niña conditions in 1933-35, led to the drought that caused food shortages on the island and the untimely demise of Dr. Ritter.  We will use atmospheric reanalyses, contemporaneous marine meteorological observations in the vicinity of islands, and historical accounts from the broader Pacific basin, to describe the evolution of the 1933-35 La Niña and how it affected the human drama as it unfolded on Floreana Island. This protracted La Niña event had impacts felt in other parts of the globe as well and in particular was a major influence on development of the 1930s Dust Bowl in the southern plains of the United States.
Spatial and temporal variability of gas content in sediments of Lake Kinneret, North of Israel
Authors: Uzhansky Ernst , Lunkov Andrey , Katsman Regina , Katsnelson Boris
Published: March 2022

Shallow gassy aquatic sediments, abundantly found in Israel and worldwide, are a source of major concern for their contribution to destabilization of coastal and marine infrastructure, ecological balance, air pollutions, and global warming. Gas bubbles within sediment change effective sediment properties, including also its geo-acoustic characteristics. Here we study the spatial and temporal variability of free gas (methane) content (θ) in shallow sediments of deep subtropical Lake Kinneret. We implemented a recently developed noninvasive acoustic methodology that allows estimating θ in sediment based on measurements of bottom reflections of sound signals and subsequent assessment of sound speed in the bottom. The experiments were carried out in the lake in April and August 2021. One- and five-second-long pulses in the frequency bands of 200 – 7000 Hz and 200 – 10000 Hz were radiated in April and August, respectively. Preliminary estimated θ at the 21-22 m isobath was 0.02−0.04% and 0.04−0.12% in April and August, respectively. Analysis of acoustic measurements shows distinct changes in θ in comparison to θ assessed in previous acoustic experiments carried out by our team in 2015-2018, when an inverse relationship between θ and lake level was found. Here we discuss other possible mechanisms, which may pre-determine the spatial and temporal variability in θ, such as ebullition of methane at the 21-22 m isobath and variability in deposited organic matter content, which vary both spatially (with seafloor depth) and seasonally.
Measuring greenhouse gas fluxes – what methods do we have versus what methods do we need?
Authors: Bastviken David , Wilk Julie , Duc Nguyen Thanh , Gålfalk Magnus , Karlson Martin , Neset Tina , Opach Tomasz , Enrich Prast Alex , Sundgren Ingrid
Published: March 2022

Appropriate methods to measure greenhouse gas (GHG) fluxes are critical for our ability to detect fluxes, understand regulation, make adequate priorities for climate change mitigation efforts, and verify that these efforts are effective. Ideally, we need reliable, accessible, and affordable measurements at relevant scales. We surveyed present GHG flux measurement methods, identified from an analysis of >11000 scientific publications and a questionnaire to sector professionals and analysed method pros and cons versus needs for novel methodology. While existing methods are well-suited for addressing certain questions, this presentation presents fundamental limitations relative to GHG flux measurement needs for verifiable and transparent action to mitigate many types of emissions. Cost and non-academic accessibility are key aspects, along with fundamental measurement performance. These method limitations contribute to the difficulties in verifying GHG mitigation efforts for transparency and accountability under the Paris agreement. Resolving this mismatch between method capacity and societal needs is urgently needed for effective climate mitigation. This type of methodological mismatch is common but seems to get high priority in other knowledge domains. The obvious need to prioritize development of accurate diagnosis methods for effective treatments in healthcare is one example. This presentation provides guidance regarding the need to prioritize the development of novel GHG flux measurement methods.