bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in atmospheric aerosols from reduced BVOC precursors in future deforestation scenarios
Authors: Vella Ryan , Forrest Matthew , Tsimpidi Alexandra , Pozzer Andrea , Hickler Thomas , Lelieveld Jos , Tost Holger
Published: March 2024

Biogenic volatile organic compounds (BVOC) are emitted in large quantities from the terrestrial biosphere and play a significant role in major atmospheric processes. Such emissions account for 90\% of the total volatile organic compound (VOC) emissions and exert a significant influence on the atmosphere's oxidation capacity. The oxidation of BVOCs yields intermediate species with lower vapour pressures, resulting in organic condensation and the formation of secondary organic aerosols (SOA). SOA directly affect the radiation budget through scattering and absorption, as well as indirectly by modifying cloud formation and distribution. It has been shown that changes in atmospheric states due to SOA contribute to feedbacks with vegetation, exerting a significant impact on global BVOC budgets. Despite their contribution to the uncertainty surrounding the impact of carbonaceous aerosols on future climate forcings, BVOC-climate feedbacks are often neglected in modelling studies. In this work, we use the chemistry-climate model EMAC coupled with the dynamic global vegetation model (DGVM) LPJ-GUESS, enabling interactive calculations of BVOC emission fluxes that respond to changes in atmospheric and vegetation states. We employ deforestation scenarios using different projections for pasture land to disturb the natural potential vegetation simulated in LPJ-GUESS. Utilising a sophisticated description of secondary organic aerosols, the direct relation of atmospheric particles originating from interactive isoprene and terpene fluxes with the atmospheric state can be analysed. Consequently, we use state-of-the-art process descriptions in EMAC to study the impacts of biogenic SOA on global radiation budgets and clouds, shedding light on potential future changes in the atmosphere resulting from perturbations in the biosphere.
A single instrument for the simultaneous monitoring of greenhouse gases and air pollutants
Authors: Bruckhuisen Jonas , Brunner Marco , Aseev Oleg , hundt Morten
Published: March 2024

Urban air pollution and greenhouse gas emissions can be attributed to a variety of sources, such as transportation, heating and buildings, waste management, industrial and agricultural production, natural events such as forest fires and many others. Monitoring air pollutants and GHG simultaneously with high selectivity and sensitivity enables to detect and evaluate their sources and sinks and to discover the interaction between them. Precise measurements at various spatial and temporal scales are required for modelling and validation of emission inventories or satellite observations. Solutions to monitor air pollutants or GHG with high precision and temporal resolution were commonly offered as “one-species-one-instrument”, leading to large, immobile measurement setups with high energy consumption. We provide a new compact laser absorption spectrometer that combines several mid-IR lasers. Our solution allows simultaneous high-precision measurements of the greenhouse gases CO2, N2O, H2O and CH4, the pollutants CO, NO, NO2, O3, SO2 and NH3 and the trace gases OCS, HONO and CH2O within a single instrument. With a time resolution of up to 10Hz is therefore well suited to detect the relations of the co-emitted pollutants and GHGs.In our contribution, we will demonstrate examples of our instruments’ applications for mobile monitoring of 10 GHGs and air pollutants in urban areas and airborne measurements with airships. Furthermore, we will present the results of parallel monitoring with our instrument and standard conventional gas analysers used for GHG and air pollutant measurements. It demonstrates the ability of our instrument to serve as an all-in-one solution and to replace up to 7 standard gas analysers opening a wide range of new mobile multi-compound gas monitoring applications, for example, in (small) airplanes or cars. Key words: multicomponent gas analysers, mid-IR laser absorption spectroscopy, mobile monitoring, GHG monitoring
Towards an understanding of the hydrological processes of greenhouse horticulture districts
Authors: la Cecilia Daniele , Venezia Accursio , Maino Davide , Camporese Matteo
Published: March 2024

The occurrence of agricultural catchments covered by plastic greenhouses is growing worldwide. Horticultural greenhouse production allows for saving irrigation water at the farm scale, but also alters the natural hydrological cycle. Currently, these alterations are not accounted for in physics-based hydrological models. In this study, we aim to couple the greenhouse climate model KASPRO1, to estimate indoor crop transpiration from outdoor meteorological variables, with the integrated surface-subsurface hydrological model CATchment HYdrology (CATHY2) to simulate the stream discharge as well as the shallow groundwater depth in an agricultural catchment (11 km2) covered by plastic greenhouses in South Italy. The dynamic presence of greenhouses, along with bare soils and vegetated lands, is mapped with the Open field and Protected Agriculture land cover Classifier (OPAC3).We first compare our simulations against indoor measurements of water use (drip- and sub-irrigation) and soil moisture dynamics at different depths at the plot scale. Next, we run CATHY at the catchment scale and compare the output against measured stream water level.The aim of our study is to validate the capabilities of KASPRO and CATHY to provide high-fidelity spatially distributed dynamic simulations of evapotranspiration and irrigation fluxes, as well as soil moisture and groundwater flows. Such capabilities are essentials to understand the implications of plastic greenhouse districts on the hydrological cycle and thus making these models useful tools for a more sustainable management of agricultural catchments.References1 De Zwart, H.F., 1996. Analyzing Energy-Saving Options in Greenhouse Cultivation Using a Simulation Model. Landbouwuniversiteit, Wageningen.2 Camporese, M., Paniconi, C., Putti, M., & Orlandini, S. (2010). Surface--subsurface flow modeling with path-based runoff routing, boundary condition-based coupling, and assimilation of multisource observation data. Water Resources Research, 46, W02512.3 la Cecilia, D., Tom, M., Stamm, C., Odermatt, D., 2023. Pixel-based mapping of open field and protected agriculture using constrained Sentinel-2 data. ISPRS Open Journal of Photogrammetry and Remote Sensing 8. https://doi.org/10.1016/j.ophoto.2023.100033. Acknowledgements: We thank the Consorzio di Bonifica in Destra del Fiume Sele for the continuous support in the MSCA-PF REWATERING project.Funding: This project has received funding from the European Union’s Horizon Europe research and innovation under the Marie Skłodowska-Curie grant agreement No. 101062255
Bipolar control on millennial atmospheric CO2 changes over the past glacial cycle
Authors: Yu Jimin , Anderson Robert , Jin Zhangdong , Ji Xuan , Thornalley David , Wu Lixin , Thouveny Nicolas , Cai Yanjun , Tan Liangcheng , Zhang Fei , Menviel Laurie , Tian Jun , Xie Xin , Rohling Eelco , McManus Jerry
Published: March 2024

Ice-core measurements show diverse atmospheric CO2 variations – increasing, decreasing or remaining stable – during millennial-scale North Atlantic cold periods called stadials. The reasons for these contrasting trends remain elusive. Ventilation of carbon-rich deep oceans can profoundly affect atmospheric CO2, but its millennial-scale history is poorly constrained. In this study, I will show a high-resolution deep-water acidity record from the Iberian Margin in the North Atlantic, a unique setting that allows us to construct a robust chronology for confident comparisons between marine and ice-core records. The new data combined with ice-core CO2 records reveal multiple ocean ventilation modes involving an interplay of the two polar regions, rather than by the Southern Ocean alone. These modes governed past deep-sea carbon storage and thereby atmospheric CO2 variations on millennial timescales. Overall, our record suggests a bipolar control on millennial atmospheric CO2 changes during the past glacial cycle.
EarthCARE's Potential to Evaluate a Global Storm-Resolving Model Using a Satellite Simulator
Authors: Roh Woosub , Satoh Masaki
Published: March 2024

EarthCARE, equipped with a suite of passive and active sensors, including Cloud Profiling Radar (CPR), Atmospheric LIDar (ATLID), Multi-Spectral Imager (MSI), and Broad Band Radiometer (BBR), is designed for comprehensive studies of clouds, aerosols, precipitation, and their radiation impact. The CPR's Doppler capability is crucial for assessing the terminal velocity of rain and ice particles and understanding convective motions.Global storm-resolving models (GSRMs, Satoh et al. 2019; Stevens et al. 2019) have been used to generate detailed simulations of mesoscale convective systems using a kilometre-scale horizontal grid. New observations, such as the Doppler velocity from EarthCARE, will provide new insights into the evaluation and improvement of a GSRM.Moreover, the utilization of satellite simulators — comprehensive radiative transfer models designed to simulate satellite signals using outputs from atmospheric models like GSRMs — plays a crucial role in this process. These simulators are integral for assessing, enhancing, and aligning numerical models with satellite observation data.This study investigates EarthCARE's potential to enhance GSRM evaluations and improvements using a satellite simulator. We also introduce our collaboration with a satellite remote sensing group in developing retrieval algorithms.
A systematic review of the hydrological and geomorphological impact of large dams in Africa
Authors: Frankl Amaury , Annys Sofie
Published: March 2024

 Despite the fact that large dams exert a significant environmental impact on the rivers they impound, a renewed 21st century interest in these hydraulic structures exists, mainly driven by the premise to make the agricultural and energy sectors climate-resilient. This study focuses on the often underexposed large dams in Africa and entails an examination of their spatial distribution and characteristics, and downstream impacts. To this end, we have created a comprehensive spatial database of 1047 large dams, which can be considered the most complete database for Africa. Together, these dams impound 949 km³ of water for irrigation (50% of dams), urban and industrial water supply (31% of dams), hydropower generation (16% of dams, with a total installed capacity of 43,567 MW) and other purposes (< 3% of dams). The findings of our systematic literature review of the hydrological and geomorphological impact of these large dams reveal a consistent augmentation in low flows, a pronounced reduction in high flows, and often, a decrease in average river flows. Furthermore, sediment trapping efficiencies within the range of 60% to 99% are documented. Although these trends exhibit broad consistency across the continent, the associated geomorphological changes frequently exhibit localized variations. Common alterations encompass riverbed incision and a narrowing of the active riverbed. Coastal erosion and the permanent opening or closing of estuaries are also recurrently observed. Additionally, a spectrum of ecological impacts is identified, ranging from thermal and hypoxia pollution to shifts in riparian woody vegetation distribution, often favouring non-native species. Although there is no one-size-fits-all solution to address these environmental externalities, our study highlights the importance of environmental impact assessments, monitoring of dam-induced impacts and environmental justice. Furthermore, the study offers insights into potential forthcoming challenges in the context of a changing climate  (32% and 44% of the dams respectively expect significant precipitation increases and decreases by 2050) and ever-high sediment yields (at 73% of the dam locations, sediment yields above 10 Mg km-2 yr-1 occur). These challenges necessitate adaptive dam operation strategies and transboundary management, and additional efforts to deal with reservoir sedimentation.
Deep Learning-Based semantic segmentation for geomorphic processes signals in tree-ring records
Authors: Zambrano Suárez Joe David , Pérez Martín Jorge , Muñoz Torrero Machado Alberto , Ballesteros-Cánovas Juan Antonio
Published: March 2024

Trees encapsulate environmental changes in their growth through the records in the tree rings, but extracting this signal proves challenging and time consuming. These challenges persist in the study of geomorphic processes, requiring meticulous and prolonged efforts by a specialised technician to identify and date growth disturbances (GD). The presence of false annual rings adds another layer of complexity to the task. 
Today, many classical computer vision-based techniques have been developed for the automatic detection of annual rings. However, to the best of our knowledge, these techniques have not been applied to the detection of GD associated with geomorphic events, which are more challenging because they do not present as clear visual patterns as annual rings. Deep learning-based architectures have shown great capacity for automatic localisation of objects in images with complex shapes.
We have applied these systems to the segmentation of evidence of geomorphological processes (i) wounds (ii) callus tissue (iii) latewood (iv) traumatic resin ducts and (v) growth rings. The deep learning (DL) architectures used were Faster R-CNN with ResNet-101-FPN backbone, YOLOv8 and a U-Net architecture. For the application of the system, it is necessary divide the image into smaller patches, and post-processing techniques for the correct unification of the predictions of each image. Training and evaluation of the networks was performed in Google Colaboratory. The algorithm was tested on 150 cores taken ad hoc from a debris flow cone in the Pyrenees (Pineta Valley), where historical debris flows have occurred. The cores were subjected to a sanding process and the images were obtained using a Canon Eos8 camera. 120 were used to train and validate and 30 to test the architectures, comparing the results obtained by a classical approach and by DL. The evaluations were performed at the pixel level using the accuracy, precision and recall metrics. After post-processing the predictions, the pixels were converted into instances and the predictions were compared with the ground truth, and the metrics Intersection over Union (IoU), precision and recall per category were calculated.
Our preliminary results suggest that, with a sufficiently large dataset, deep learning-based models can capture sufficient information to identify the complex patterns to be classified. This implies that it is possible to achieve a model capable of automatically identifying geomorphological event signals, thereby speeding up the process of obtaining evidence. This opens the possibility of having proposals of event signals without subjective bias, obtaining in different studies, evidence datasets made with a homogeneous and systematised criterion.
Pliocene-Pleistocene orbital cycle transition of summer sea surface temperature in the mid-latitude North Atlantic
Authors: Pang Xiaolei , Voelker Antje , Ding Xuan
Published: March 2024

The Pliocene-Pleistocene transition marks a significant period in Earth’s climate history. During this period, the climate shifted from the relatively stable and warm unipolar cool-house climate to the bipolar glaciated climate states of the ice-house associated with the gradual development of the Northern Hemisphere Glaciation (NHG) . The onset of the NHG (oNHG) is traced back to approximately 3.6 million years ago (Ma). This was followed by an intensification of the NHG (iNHG) around 2.7 Ma, coinciding with a substantial reorganization of oceanic and atmospheric circulation in the North Atlantic. Despite these shifts, reconstructed alkenone-based sea surface temperature (SST) records from the mid- to high-latitude North Atlantic indicate persistent obliquity-dominated cycles, with a noticeable absence of the precession cycle. In this study, we present new high resolution Globigerinoides ruber (white) Mg/Ca-based summer SST records from the early Late Pliocene spanning from 3650 – 3370 thousand years ago (ka) at the IODP Site U1313 (41°N, 33°W, 3412m) in the mid-latitude North Atlantic. Contrary to the previous alkenone-based SST records, our Mg/Ca-based SST records reveal a dominant precession cycle. When compared with early Pleistocene G. ruber Mg/Ca-based SST records, we observed a notable transition in the dominant cycle from precession to obliquity, accompanied by a doubling increase in amplitude. These results indicate a progressively amplified effect on the obliquity cycle, correlated with the progressive growth of the Northern Hemisphere ice sheets.
Uncovering Sugar Beet Water Uptake Through Stable Water Isotope Analysis
Authors: Santos Pires Sabrina , Bodner Gernot , Stumpp Christine
Published: March 2024

The impact of climate change on crop production, marked by increased drought and heat stress, poses significant challenges to agricultural productivity. To overcome these challenges, it is essential to understand how crops take up water through their roots. Sugar beet farming holds immense importance in Austria, especially in the eastern region, where limited water supply constrains crop production. Consequently, strategies need to be developed to enhance water resource utilization and improve plant resilience against drought for sustainable sugar beet production. Therefore, in controlled laboratory experiments, a new method was developed to determine the distribution of water uptake by plant roots in response to dry topsoil conditions and variations in root depth for different sugar beet cultivars. Stable water isotope techniques were used to trace labelled water in rhizobox experiments from the soil to plant transpiration. The water-vapor equilibration technique, commonly used for soil samples, was adapted to measure water-stable isotopes in transpired water on live plants. Leaves were placed in Ziploc bags, inflated with dry air, and allowed to stabilize for at least 16 hours. After equilibration, the bag was punctured, and the equilibrated air and transpired vapor were directed to a laser spectrometer for stable water isotope analysis (2H/1H, 18O/16O). These isotopic ratios provided insights into the depth of root water uptake, aiding in the selection of crop varieties with effective water extraction from deep soil layers. Results indicate that sugar beets develop long roots capable of taking up water from deeper soil layers and adjusting their water uptake mechanisms when topsoil water is scarce. In summary, this study explores the crucial issue of water uptake in sugar beet cultivation, particularly in the context of climate change and water limitations. The findings will inform more efficient agricultural practices, enhance crop resilience, and support sustainable water resource management.
Assessing glyphosate movement through different agricultural systems with a shallow water table: insights from an inverse dual permeability model
Authors: Piazzon Giovanna , Longo Matteo , Rocco Sebastiano , Morari Francesco , Dal Ferro Nicola
Published: March 2024

The movement dynamics of glyphosate (GLY) in soil can be highly complex and challenging to predict, because its high water solubility and strong propensity to soil particle adsorption can interact with agricultural management practices, e.g. tillage operations and water table management. This can make GLY i) sensitive to nonuniform leaching via preferential flow paths into the groundwater before it can degrade, ii) difficult to model according to uniform flows. The aim of this study was to understand GLY dynamics in different agricultural systems of the low-lying Venetian plain, by calibrating a dual permeability model embedded in HYDRUS-1D using a series of GLY experimental data that were collected in the field, and compare it with a dual porosity mobile-immobile approach. Experimental data came from eight drainable lysimeters, where two shallow water table depths (60 cm and 120 cm deep) were compared in conventional (CV) and conservation agriculture (CA) systems as representative of the low-lying Venetian plain conditions (NE Italy). On May 2019, GLY and a tracer (KBr) were applied on bare soil (in CV) and rye that was used as a cover crop, in CA. After the distribution, soil (0-5, 5-15 cm deep) and soil-pore water (15, 30, 60 cm deep) samples were collected for 48 days to follow solutes dynamics. At the same depths, soil moisture and matric potential were monitored using TDR probes and electronic tensiometers. An automated system modulated the suction through matric potential readings combined with an electronic vacuum regulator. The HYDRUS 1-D software package was employed for inverse modelling of soil properties, first through parameterization and matric potential results, while solute movement parameters were calibrated based on GLY and KBr results from soil and water samples. Experimental results showed that GLY was found at different depths, especially soon after its distribution as dependent on intense rainfall events. The MIM model failed to predict any GLY movement, due to its high adsorption coefficient that hindered any GLY exchange between the immobile and mobile phases. In fact, experimental observations revealed that a preferential flow occurred down to the deepest layers (60 cm deep), even in the presence of poorly structured soil and irrespective of both the groundwater level and the cultivation system. In contrast, the dual permeability model provided a more accurate description of GLY dynamics in soil, successfully predicting the observed bypass flow timing experiment. Therefore, dual permeability model seems crucial for describing GLY dynamics in agroecosystems, enabling more accurate predictions of its potential pathways. 
Land Reclamation Controls on Estuarine Morphological Evolution
Authors: Schrijvershof Reinier , van Maren Bas , van der Wegen Mick , Hoitink Ton
Published: March 2024

The morphological configuration of estuaries and tidal basins influences future development because the channel-flat pattern and geometry control tidal dynamics and, as a result, residual sediment transport patterns. Large-scale human alteration of estuarine plan-form and channel dimensions, as a result of land reclamation, influences long-term evolution, because the existing balance of sediment import versus export is disrupted. The morphodynamic response to land reclamation is, however, slow, impacting the system for decades to centuries. Consequently, there are usually multiple human interventions cumulatively impacting the system. Our understanding of the cumulative effects of land reclamation and other anthropogenic interference is limited because observations usually do not span the complete morphological adaptation time. The Ems estuary (bordering The Netherlands and Germany) provides an unique site to study the effects of the cumulative impact of land reclamations and 20th-century human interference. Extensive storm surge-formed basins have been gradually reclaimed over a period of 500 years in this well-documented estuary, and dredging works dominated in the past century. Our objective is to quantify the effects of land reclamations and channel dredging on the historic evolution of the Ems estuary from century-scale observations combined with numerical morphodynamic modelling.We compiled a digitized bathymetric dataset, spanning nearly the full reclamation period, from historical maps, nautical charts, and recent sounding observations. The dataset was used to reconstruct the morphological evolution of the estuary over the past 500 years. The centennial-scale morphodynamic trends show that the system responded to land reclamation by subtidal infilling and evolved from a multichannel system separated by shoals to a single channel system flanked by fringing flats. The long-term geometric changes show that the main system-scale morphodynamic adaptation is controlled by the effects of land reclamation. The present-day evolution is additionally influenced by the effects of 20th-century dredging works.A process-based morphodynamic model (Delft3D-FM), forced with a synthetic spring-neap tidal cycle, was used to investigate the Ems estuary channel evolution in response to historical land reclamations. Simulation results showcase the transformation from an initially flat-bed bathymetry to a system with multiple channels and tidal flats when historic storm surge basins provide extensive intertidal areas. Simulations in which these former storm surge basins are reclaimed result in a single-channel system, confirming the influence of land reclamations on the observed evolution. The results of this study emphasize that, contrary to what is generally assumed, pre-dredging estuarine morphologies are often far from pristine. Ongoing research focuses on quantifying the interplay between natural and human-driven factors in century-scale channel evolution.
Carbon Sequestration and Mitigation of Agricultural Greenhouse Gas Emissions through management: Insight from an incubation experiment
Authors: Bibi Sobia , Ahmad Hassan , Wanek Wolfgang , Zaman Mohammad , Vlasimsky Magdeline , Heiling Maria , Pucher Reinhard , Dercon Gerd
Published: March 2024

Climate change poses a significant threat to soil quality and global food security, with projections indicating potential crop yield declines of 17% by 2050. Simultaneously, agriculture contributes to an estimated 24% of all greenhouse gas (GHG) emissions. The dynamics of carbon (C) and nitrogen (N) play a pivotal role in GHG emissions and soil C sequestration, yet further research is needed on how management practices influence these dynamics. To address these challenges and provide data can facilitate efficient resource utilization in agricultural production, an incubation experiment was conducted to provide data on the impact of management options on C sequestration and GHG emissions from agricultural soils. The experiment took place in 850 mL glass jars under controlled conditions at 60% water-filled pore space and a temperature of 25°C. Composite soil samples, derived from a moderately fertile soil (2-3% SOC) from Grabenegg, Austria, at a depth of 0-15 cm, were subjected to five treatments: 1) control, 2) labeled urea, 3) inhibitor and labeled urea, 4) biochar + 15N labeled urea, and 5) inhibitor and biochar and labeled urea. The 15N-labeled urea (5% atom excess) was applied at a rate of 150 kg N ha-1, while biochar was applied at 2% of the soil by dry mass basis. A neon inhibitor which includes NBPT to limit nitrogen loss into the atmosphere as ammonia and DCD to reduce leaching, were applied at a rate of 4 mL per 100g urea as instructed by the manufacturer. All treatments were replicated four times. Soil and gas samples were collected on days 1, 3, 8, 15, 24, 31, 38, 45, 52, and 59 after treatment application. Gas samples were collected over a two hour period each day. Soil samples were analyzed for pH, soluble organic C, and mineral-N (NH4+, NO3-), while gas samples were analyzed using a gas chromatograph (GC) for NO2, CO2, and CH4. Preliminary results indicate that the addition of biochar increased soil C content, aligning with expectations from prior studies and that the addition of the inhibitor had a discernible impact on the pathways of nitrogen in the study samples. The use of isotopic methods and GHG measurements can furnish critical data supporting the most efficient use of resources for both climate mitigation and adaptation. 
The significance of tides for offshore wind wake effects on coastal ocean dynamics
Authors: Christiansen Nils , Daewel Ute , Schrum Corinna
Published: March 2024

As offshore wind development increases, marine environments are increasingly affected by offshore wind farm wakes and their impact on hydrodynamic processes. Recent studies have shown that wind wakes can influence ocean circulation and stratification through changes in surface wind speed. However, their results indicate that the wake effects are attenuated in areas that are strongly determined by tidal currents. In this study, we look deeper into the wake-induced hydrodynamic processes and the influence of tides, aiming to understand the role of local hydrodynamic conditions on the magnitude of emerging wake effects. For this, we use high-resolution unstructured-grid modeling, focusing on offshore wind development for tidal and non-tidal scenarios in the shallow North Sea. The model simulations show the effects arising from wind speed reductions and demonstrate the impact of tidal processes. We identified that tidal currents can disturb the changes in surface current velocity and even mitigate the impact on the mean flow field around offshore wind farms. In shallow waters, tidal stirring superimposes wake-induced processes and can influence the changes in vertical mixing and stratification. Our simulations reveal that tides eventually mitigate the impacts of offshore wind farm wakes on the North Sea hydrodynamics. These findings become important when assessing offshore wind farm effects in different marine environments and estimating the extent of the anthropogenic disturbances.
Post-eruption tropical water vapour transport: Pinatubo and Hunga Tonga-Hunga Ha’apai
Authors: Zhou Xin , Zhang Wenhui , Mann Graham , Feng Wuhu , Dhomse Sandip , Chipperfield Martyn
Published: March 2024

The June 1991 Pinatubo and January 2022 Hunga Tonga-Hunga Ha’apai (HTHH) are the two most explosive tropical volcanic eruptions in 30 years. The two, one with high sulfur dioxide (SO2) emission and the other high water vapour (H2O) emission, provide two different paradigm cases to understand the post-eruption tropical transport. Here we use the VolMIP short-term climate-response experiments with the UK Earth System Model (UKESM1) to explore the post-eruption tropical H2O transport after a high-SO2 case.Aerosol-absorptive heating causes peak SWV increases of 17% (~1 ppmv) and 10% (0.5 ppmv) at 100 hPa and 50 hPa, at ~18 months and ~23 months post-eruption, respectively. The main SWV increase occurs only after the descending aerosol heating reaches the tropopause, suggesting a key role for aerosol microphysical processes (sedimentation rate). This increase is strongly modulated by ENSO variability. With a consistent biased Quai-Biannual Oscillation (QBO) towards the westerly phase, tropical upwelling under different ENSO conditions strongly mediates this effect.We will also discuss the observed tropical H2O entry after HTHH eruption. With a triple-dip La Niña background and the strong H2O-induced cooling in the lower stratosphere, the tropical H2O transport through 2022/23 is dominated by the volcanic forcing and the sea surface temperature. An up-to-date observation from satellite data is used for analysing this unique HTHH volcanic forcing, while future modelling is needed for a tangible impact.
Links between subtropical high-pressure systems and stratocumulus clouds variation
Authors: Ding Hairu , Stevens Bjorn , Schmidt Hauke
Published: March 2024

Stratocumulus clouds contribute significantly to the global energy budget as they are the Earth’s predominant cloud type and contribute strongly to Earth’s albedo. They are known to predominate in the subtropics, especially on the eastern edge of the subtropical highs. Previous studies have confirmed the importance of these highs for stratocumulus clouds, but how much it varies can influence the cloudiness hasn’t been quantified, yet. Our study investigates this relation for both the annual cycle and deseasonalized time series for the five major subtropical high-pressure regions. It has been shown that the estimated cloud top entrainment index (ECTEI) is a useful predictor for the stratocumulus cloud fraction for both time scales. We show, however, that the variation of the highs provides additional information on the fraction change on an annual cycle. The Northern Hemisphere is more sensitive to the highs change compared to the Southern Hemisphere. Variations in the structure, area, and location of subtropical highs are not considered the dominant influencing factors (correlations about 0.3~0.4). Nevertheless, we found a qualitative preference that stratocumulus clouds prefer a flatter, large, and westward subtropical high.
Thin Ice, Large Impact: Temporal and spatial trends of Arctic thermodynamic and dynamic sea ice thickness change
Authors: von Albedyll Luisa , Ricker Robert
Published: March 2024

The Arctic Ocean's transition from perennial sea ice to more ice-free summers has halved sea ice thickness in the last six decades, significantly impacting the Arctic climate and ecosystem. Recent trends show a slowing in ice thickness and volume decline, prompting a need to investigate the underlying seasonal and long-term feedback mechanisms of sea ice thickness change. To do so, we use a Lagrangian drift-aware sea ice thickness product (DA-SIT), combined with extensive data on thermodynamic growth conditions and sea ice deformation, to quantify thermodynamic and dynamic thickness change in selected Arctic regions. A key focus is the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, which provided regional-scale analysis of seasonal sea ice thickness change using airborne ice thickness measurements, sea ice deformation, and in-situ snow and thermodynamic growth data. Our study extends these findings to larger temporal and spatial scales, evaluating their pan-Arctic applicability using long-term satellite datasets. We compare the MOSAiC trajectory with different dynamic regimes and ask how representative the conditions were for the “old” and the “new” Arctic. This analysis is key to understanding future sea ice thickness change, which is of great relevance for many climate and ecosystem processes.
Spatiotemporal Evolution of Seismic Swarms in the light of the Continuous Time Random Walk Model
Authors: Michas Georgios , Vallianatos Filippos
Published: March 2024

Seismic swarms are characterized by intense seismic activity strongly clustered in time and space and without the occurrence of a major event that can be considered as the mainshock. Such intense seismic activity is most commonly associated with external aseismic factors, as pore-fluid pressure diffusion, aseismic creep, or magmatic intrusion that can perturb the regional stresses locally triggering the observed seismicity. These factors can control the spatiotemporal evolution of seismic swarms, frequently exhibiting spatial expansion and migration of event hypocenters with time. This phenomenon, termed as earthquake diffusion, can be highly anisotropic and complex, with earthquakes occurring preferentially along fractures and zones of weakness within the heterogeneous crust, presenting anisotropic diffusivities that may locally vary over several orders of magnitude. The efficient modelling of the complex spatiotemporal evolution of seismic swarms, thus, represents a major challenge. Herein, we develop a stochastic framework based on the well-established Continuous Time Random Walk (CTRW) model, to map the spatiotemporal evolution of seismic swarms. Within this context, earthquake occurrence is considered as a point-process in space and time, with jump lengths and waiting times between successive earthquakes drawn from a joint probability density function. The spatiotemporal evolution of seismicity is then described with an appropriate master equation and the time-fractional diffusion equation (TFDE). The applicability of the model is demonstrated in the 2014 Long Valley Caldera (California) seismic swarm, which has been associated with a pore-fluid pressure triggering mechanism. Statistical analysis of the seismic swarm in the light of the CTRW model shows that the mean squared distance of event hypocenters grows slowly with time, with a diffusion exponent much lower than unity, as well as a broad waiting times distribution with asymptotic power law behavior. Such properties are intrinsic characteristics of anomalous earthquake diffusion and particularly subdiffusion. Furthermore, the asymptotic solution of the TFDE can successfully capture the main features of earthquake progression in time and space, showing a peak of event concentration close to the initial source of the stress perturbation and a stretched relaxation of seismicity with distance. Overall, the results demonstrate that the CTRW model and the TFDE can efficiently be used to decipher the complex spatiotemporal evolution of seismic swarms.AcknowledgementsThe research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (Project Number: 00256). 
Supersaturation and critical size of cloud condensation nuclei in marine stratus clouds
Authors: Svensmark Henrik , Enghoff Martin Bødker , Svensmark Jacob , Thaler Irina , Shaviv Nir
Published: March 2024

The critical size of aerosols is the size where they can serve as cloud condensation nuclei and thus get activated into cloud drops. This size depends on the supersaturation of water in a given air mass. The lower the critical size is, the more the cloud formation process is sensitive to changes in the formation of secondary aerosol since they experience large losses as they grow in size.
Using observations of marine stratus clouds outside the coast of California, a functional relationship between supersaturation and the number concentration of cloud condensation nuclei has been found (Hudson et al., GRL 37(21), 2010 and Hudson and Noble, J. Atmos. Sci. 71(1), 2014).
In this work, we use liquid drop density estimates based on satellite data of optical thickness and liquid water path from the MODIS instrument combined with the above relation to estimate a global map of supersaturation. Applying Köhler's theory to this map, a corresponding map of critical sizes has been made.
We find that supersaturation is generally in the range of 0.5-1.0%, which results in a critical size in the range of 25-30 nm, which is lower than the generally used size of about 60 nm. The high supersaturations are supported by observations from the ATom measurement campaign (Brock et al, doi: 10.3334/ORNLDAAC/2111, 2022), at different supersaturations.
Furthermore, the “pyrcel” cloud parcel model (Rothenberg and Want, J. Atmos. Sci. 73(3), 2016) is used to investigate the observational relationship between supersaturation and cloud droplets/cloud condensation nuclei.
The results hint that cloud formation may be more sensitive to changes in secondary aerosols than previously thought.
Patterns in dusty cirrus cloud formation mechanisms revealed by LES modeling study
Authors: Juurikkala Kasper , Raatikainen Tomi , Laaksonen Ari
Published: March 2024

Dusty cirrus clouds, a rare phenomenon occurring approximately a few times a year globally, are associated with desert dust plumes in the upper troposphere. The formation of these clouds involves a high-humidity layer above a mineral dust-rich layer. In the intermediate layer between these two layers, initially, a thin cirrus cloud forms heterogeneously on the mineral dust particles. The latent heat release caused by the ice nucleation and radiative cooling above the thin cirrus cloud layer cause instability and convection to occur. This convection uplifts mineral dust particles even higher until the humid layer is fully mixed with the mineral dust, resulting in the dusty cirrus covering the humid layer.The objective of this study is to investigate the formation mechanisms of dusty cirrus clouds. Addressing the challenges highlighted by Seifert et al. (2023), current atmospheric models struggle to predict these events. This work aims to validate the hypothesis presented by Seifert and further advance the understanding of the formation mechanisms. The study involves a simulation study conducted using the UCLALES-SALSA large-eddy model (Tonttila et al., 2017). A case study is performed using the atmospheric conditions present during Saharan dust plumes over Europe in recent years.The simulated dusty cirrus clouds show that the upward transport of the mineral dust is not as effective as in the regional model study by Seifert et al. (2023). This is because the mineral dust which gets uplifted initially sediments down back to the original mineral dust layer with the sedimenting ice crystals. Also, the predominant mechanism for the instabilization of the air in the initial stages of the cloud formation is the latent heat release caused by the ice nucleation and the growth of the ice crystals, rather than the radiative cooling suggested by Seifert et al. (2023).In the future, simulations will be conducted using idealized cases to comprehensively understand the most relevant mechanisms involved in the formation of dusty cirrus clouds.ReferencesSeifert, A., Bachmann, V., Filipitsch, F., Förstner, J., Grams, C. M., Hoshyaripour, G. A., Quinting, J., Rohde, A., Vogel, H., Wagner, A., and Vogel, B. (2023) Aerosol–cloud–radiation interaction during Saharan dust episodes: the dusty cirrus puzzle, Atmos. Chem. Phys., 23, 6409–6430Tonttila, J., Maalick, Z., Raatikainen, T., Kokkola, H., Kühn, T. and Romakkaniemi, S. (2017).UCLALES-SALSA v1.0: a large-eddy model with interactive sectional microphysics for aerosol,clouds and precipitation. Geosci. Model Dev., 10, 169-188
Emissions Of Methane And Volatile Organic Compounds From Offshore Oil Loading Using Shuttle Tankers 
Authors: Purvis Ruth , Lee James , Moore Tom , Burton Ralph , Hopkins James , Lewis Ally , Mobbs Stephen , Young Stuart
Published: March 2024

The full range of emissions from oil and gas production, especially offshore, is still not fully understood due to the vast number of sources and lack of observational data. Emissions from shuttle tanker loading are not well characterised. The latest National Atmospheric Emissions Inventory United Kingdom Green House Gas (NAEI_UK_GHG) Inventory Improvement Report (July 2022) cited evidence for emissions factors from methane (CH4) and non methane volatile organics (NMVOCS) compounds from oil loading as a future priority research area. In the UK almost 35 % of oil fields are designated “OTLS” which means that the liquids produced must be offloaded and transferred to onshore terminals/refineries using shuttle tankers.This work shows initial results from a campaign in October 2023 designed to investigate CH4 and NMVOC emissions from oil loading to shuttle tankers over the whole loading cycle. The project uses aircraft measurements along with different modelling techniques to evaluate emissions from the complete tanker loading process. The shuttle tanker data will also be looked at to see what abatement measures and equipment are on board.
Imaging of the Mantle Transition Zone with SS Precursors in the Iceland-Mid-Atlantic Ridge Region
Authors: Jiang Xiuxuan , Chen Yunfeng , Obou ́e Yapo Abol ́e Serge Innocent , Wang Jingchuan
Published: March 2024

The nature of Iceland hotspot, located on the Mid-Atlantic Ridge, has been subject of contentious debate. Earlier seismic tomographic studies have suggested the presence of a deep mantle plume or confined to the upper mantle without a clear plume affinity. In this study, we utilize SS precursors to image the Mantle Transition Zone (MTZ) beneath Iceland. We collected a large SS precursor dataset that contains teleseismic recordings from all available global broadband stations between year 1976 and 2023. The resulting dataset enables a dense sampling of the Iceland and the Mid-Atlantic Ridge (i.e., 40°-80° N and -70°W to 10° E) with more than 3000 high-quality SS precursor waveforms. We adopted a recently proposed Robust Damped Rank-Reduction method to process the SS precursor data, which enables exploiting the signal coherency in multi-dimensional (4D) data and significantly improving the quality of the weak precursory arrivals. Seismic imaging based on the processed SS precursors effectively captures regional-scale topographic variations of mantle discontinuities, eliminates contaminating noises that produce small-scale artifacts, and enhances the lateral coherency of the MTZ structure. The resulting MTZ images reveal that the 410 km discontinuities are depressed by 5 km compared to regional average, whereas the 660 km discontinuities are uplifted by 6 km, leading to a MTZ of 230 km thick beneath Iceland. The region of depressed 410 extends southwards from the eastern edge of Greenland along the Mid-Atlantic Ridge for a distance about 20 degrees. In comparison, the elevation of 660 is more wide-spread, reaching as far as the northwestern end of Greenland. These observations suggest the interaction of a deep mantle plume with the 660 km discontinuity in a broad area covering the north Mid-Atlantic Ridge. The thick lithosphere beneath Greenland may have channeled the mantle flow towards the ridge, thereby causing the thinning of the MTZ centering on Iceland. In the southeast of the study area, our model also reveals a thinning area, isolated from the Iceland anomaly. The observed complex MTZ topography, in conjunction with multiple low-velocity centers in global tomographic models, may suggest the presence of a bifurcated, deep mantle plume originated from the lower mantle that may feed the shallow hotspots near the Iceland-Mid-Atlantic Ridge.
Storage potential of CO2 by repurposing oil and gas-related injection wells in the Montney Play, northeast British Columbia, Canada
Authors: Yu Hongyu , Wang Bei , Kao Honn , Visser Ryan , Jobin Malakai
Published: March 2024

From 2005 to 2020, Canada achieved a 9.3% reduction in green house gas emission (69 Mt CO2 eq), meanwhile British Columbia witnessed a 5% increase (3.0 Mt CO2 eq) from 2007 to 2019. Exploiting unconventional oil and gas resources in northeast British Columbia (NEBC) has become the province’s second-largest source of greenhouse gas emissions. In pursuit of a cost-effective and seismic risk-aware approach for carbon emission reduction, this study evaluates the CO2 geological storage capacity in NEBC with a focus on repurposing existing injection wells for carbon storage.We particularly emphasize the Montney and Debolt formations. These formations are the main targets of a diverse array of injection wells, including those for hydraulic fracturing, enhanced hydrocarbon recovery, and wastewater disposal. Three trapping mechanisms in the NEBC area are examined: physical and solubility trapping for wastewater disposal wells in the Debolt Formation, and physical and mineral trapping for hydraulic fracturing and enhanced recovery wells in the Montney Formation. Furthermore, we incorporate an assessment of seismic hazards, informed by the latest insights into injection-induced seismicity in NEBC, as a potential indicator of CO2 leakage risk.Our findings underscore the favorable conditions of the Debolt Formation with lower seismicity hazard and a substantial CO2 storage capacity (19.3 Gt; ~284.4 years of CO2 emissions in BC). Depleted oil and gas reservoirs within the Montney Formation are also deemed suitable for CO2 storage, estimated at 1671.8 Mt (approximately 24.5 years), particularly in the Upper Montney due to its higher storage capacity and lower seismic risk.Overall, this research offers an assessment of CO2 geological storage potential at the formation-scale in NEBC. The emphasis on well suitability and seismic risks effectively bridges the gap between the regional-scale geological assessments and site-scale engineering evaluations. It paves the path for future studies on addressing more practical topics related to the choices of project sites and injection strategies.