bluuebunny/crossref_metadata_2025 huggingface dataset:
Meteorological variables controlling the forest fire over the Himalayas
Authors: Khadke Leena , Ghosh Subimal
Published: February 2023

Forest fire is the main disturbance for the Himalayan ecosystems, which impacts the regional and global carbon cycle, climate, forest succession, and tree density. Forest fires can occur due to both natural processes and anthropogenic factors. The fires over the Himalayas are mostly observed in the summer and pre-monsoon season, with large interannual variability. The primary objective of the present study is to identify the main meteorological drivers controlling forest fires over the Himalayas from March to June. The study performed statistical analysis on the daily and monthly observed/reanalysis climate data between 2001-2016. We used precipitation (P), temperature (T), and soil moisture (SM) from the climate prediction center and Vapor Pressure Deficient (VPD) from ECMWF-ERA5. The three satellite-based datasets for the Burned Area (BA) are accessed from Global Fire Emissions Database version 4 (GFEDs), Collection 6 Moderate Resolution Imaging Spectroradiometer (MODIS C6), and the European Space Agency Fire Climate Change Initiative version 5.1 (FireCCI51 – CEDA archive). The preliminary results show that all three BA has significant spatial and temporal/interannual variability. Meteorological variables such as P, T, SM, and VPD indicate strong interannual variability with rising slopes throughout the study period. Among these, P and SM indicate a significant trend over the central and northeast parts of the Himalayas. The VPD has a maximum significant positive correlation with BA for all three datasets (highest for GFED). The daily climatology suggests that VPD drops with an increase in P and follows the peaks of increasing T. The VPD rises until the end of April and starts falling from May due to pre-monsoon showers. The study observed that the varying amount of BA follows the peaks of high VPD, high temperature, and dry days (PThreshold < 1mm). The northeast part of the Himalayas experiences major fires in March-April because of the substantial number of dry days and reduces in May-June due to pre-monsoon showers. In the northwest part, the amount of BA is high in May-June, despite having a smaller number of high VPD and dry days over the region. In the future, the study will focus on the impact of Himalayas forest fires on the atmospheric dust loading at a high temporal scale which can potentially trigger forest fires in adjacent regions.
Sub-frontal niches of marine plankton driven by transport and trophic interactions at ocean fronts
Authors: Mangolte Inès , Lévy Marina , Ohman Mark
Published: February 2023

Observations and theory have suggested that ocean fronts are ecological hotspots, associated with higher diversity and biomass across many trophic levels. The hypothesis that these hotspots are driven by frontal nutrient injections is seemingly supported by the frequent observation of opportunistic diatoms at fronts, but the behavior of the rest of the plankton community is largely unknown.Here we investigate the organization of planktonic communities across fronts by analyzing 8 high resolution transects in the California Current Ecosystem containing extensive data for 24 groups of bacteria, phytoplankton and zooplankton.We find that a distinct frontal plankton community characterized by enhanced biomass of not only diatoms and copepods but many other groups of plankton such as chaetognaths, rhizarians and appendicularians emerges over most fronts. Importantly, we find spatial variability at a finer scale (typically 1-5 km) than the width of the front itself (typically 10-30 km) with peaks of different plankton taxa at different locations across the width of a front. Our results suggest that multiple processes, including both horizontal stirring and biotic interactions, are responsible for creating this fine-scale patchiness.
The combined effect of global warming and AMOC collapse on the Amazon Forest
Authors: Nian Da , Bathiany Sebastian , Ben-Yami Maya , Blaschke Lana , Hirota Marina , Rodrigues Regina , Boers Niklas
Published: February 2023

The Amazon forest is at risk of dieback due to climate change, in particular decreasing mean annual precipitation (MAP) and increasing mean annual temperature (MAT). This study assesses the influence on South American vegetation under two possible future climate change scenarios: global warming, and global warming combined with an AMOC collapse. We consider MAT and MAP as control parameters and use their projected changes from climate model simulations with the Earth System Model HadGEM3. We then estimate the most probable states of vegetation based on empirical relationships between these parameters and tree cover. Our results suggest that an AMOC collapse would not contribute to further rainforest dieback over most of the Amazon basin. Instead, in parts of tropical South America, MAP increases and MAT decreases after AMOC collapse, which tends to stabilize the Amazon forest and hence delay the Amazon dieback compared to the default global warming scenario.
Sharing Air Quality Monitoring Activities at a University in Nigeria
Authors: Sa'id Rabia Salihu , Galadanci Najib Yusuf , Badamasi Murtala Muhammad , Rabiu A. Babatunde , Jenkins Gregory S.
Published: February 2023

Breathing is life and the quality of air we breathe is important for good quality of living. At the Bayero University in Kano, Nigeria, the Space Weather and Atmospheric Physics Laboratory has collaborated with the Center for Atmospheric Research to establish a network of air quality monitoring and data gathering techniques through setthing up monitoring stations and recently collaborating with the Alliance for education, Science, Engineering and Design in Africa (AESEDA), using low cost air quality monitoring devices and combining the ground-based data with sattelite data to give meaningful and useful data for safety. Data of air pollutants measured and how they correlate with increasein respiratory tract infections during the pandemic were studied. We present the activities of air quality monitoring during the period of 2020; the hieght of the pandemic and the period thereafter. Findings show that there is a need to be concerned as readings of impact of air pollutants are high and most times hiher than the minimum EPA standards.
Attribution of climate change imprint on riverine nutrient export from diffuse pollution sources to African coastal waters
Authors: Nkwasa Albert , Chawanda Celray James , van Griensven Ann
Published: February 2023

Nutrient pollution derived from anthropogenic activities impacts both inland and coastal waters, altering the aquatic ecosystem and resulting in serious environmental issues. As climate change is affecting most of the hydroclimatic variables across the world, a fundamental concern in river ecology is therefore to understand the degree to which the spatial patterns and variations of nutrient concentration and loading in rivers during the last decades can be associated with climate change. This study detects and attributes the impact of historical climate change on long-term changes in the flux of nutrients from diffuse pollution sources into the coastal waters of Africa. An impact attribution approach is employed by forcing a continental process-based water quality model (Soil and Water Assessment Tool – SWAT+) for Africa with a set of observational and counterfactual climate data from the impact attribution setup of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a). The nonparametric Mann–Kendall test is used to identify trends while long-term mean annual river nutrient simulation differences between a model setup with observational and counterfactual climate data are calculated to allow for quantification of the climate change attribution. Results show spatial differences with climate change reasonably contributing to both an increase and decrease of both riverine Total Nitrogen and Total Phosphorus to African coastal waters. However, the climate change imprint on the riverine nutrient export is starting to emerge within the 21st century years for most rivers. These findings show spatial differences in the sensitivity of impacts of climate on riverine TP and TN export to coastal waters while highlighting the most impacted rivers in Africa.
The Effect of Laser-induced Heating on Moganite, Silanole and Quartz during Raman Spectroscopy
Authors: Tsukada Yasumoto , Bowden Stephen , Schmid Patrick
Published: February 2023

Moganite is a silica polymorph found intergrown with microcrystalline quartz. Raman spectroscopy is used to detect moganite using a band at 501 cm-1, generated by the vibration of a four-membered tetrahedral SiO2. This band is numerically distinct from the most intense band used to identify quartz at 465cm-1, and thus Raman spectroscopy might be considered a reliable methodology to detect moganite. However, the moganite detection using Raman spectra must be done with caution since a band at 503 cm-1 can be caused by a Si-O vibration of silanole (SiOH), and thus the two bands interfere and may mingle. Such interference might be mitigated or increased by sample preparation, but it has not previously been shown with certainty whether powdered or intact rock surfaces, would exhibit the greatest interference. Here, we present a Raman spectroscopic study of different particle sizes on moganite and flint to investigate how it affects moganite detection. We found a Raman band in pristine flint with a similar peak position to moganite, but subsequent to heat treatment at 700 ˚C for 6 hours, the band disappeared indicating the presence of silanole rather than moganite. Powdering the sample in combination with the use of higher laser powers increased this effect and the relative intensity of the silanole band. Overall, the Raman spectrum of flint was found to be more sensitive to laser-power-induced artifacts than moganite. Aggregated quartz powder is known to be affected by laser-induced heating during Raman spectroscopy. However, the effect of the heating on silanole and moganite bands is not as well documented. The peak shift of moganite has a similar trend to the phase transition detected by Raman Spectroscopy and XRD with heat thus the two approaches are consistent. Furthermore, the silanole band is known to change its position by 6 cm-1 at heating from room temperature to 600 ˚C. Based on the results from other research, the peak shift and broadening in the present study can be interpreted as an effect of laser-induced heating. To date, for mineral analyses, the number of studies reporting the effects of laser-induced heating on minerals is limited, which contrasts strongly with Raman spectroscopy of organic materials. The result in the present study suggests that the band shift of silanole and the transition of α-β moganite can be caused by the heat of the laser should be taken into consideration especially when small particle size moganite is being identified by Raman Spectrum. However, this same sensitivity to temperature may indicate potential as a measure of paleotemperature.
Bayesian inference of β-meteoroid parameters with Solar Orbiter
Authors: Kočiščák Samuel , Holbek Sørbye Sigrunn , Kvammen Andreas , Mann Ingrid , Zaslavsky Arnaud , Theodorsen Audun
Published: February 2023

Solar Orbiter’s Radio and Plasma Waves instrument (SolO/RPW) is capable of detecting hypervelocity dust impacts onto the spacecraft through the fast electrical phenomena that accompany the process. SolO operates within 1AU, in the environment with high density of β-meteoroids – dust grains escaping from the proximity of the Sun due to radiation pressure force counteracting gravity. Recently, Convolutional Neural Network (CNN) classified data were made available[1], analyzing all the recorded waveforms and providing us with the highest quality dataset of the impact events to date.We present a model for the in-situ impact rate on SolO/RPW assuming β-meteoroids are the main component of the detections. We fit the model to the highest quality available CNN data assisted by Integrated Nested Laplace Approximation (INLA) for Bayesian inference with informative priors[2].Taking into account spacecraft’s position and its velocity vector, we are able to infer mean radial velocity of the detected dust grains to be 63 ± 7 km/s. We are also able to constrain β-meteoroid predominance and dust’s mean acceleration and by extension constrain its mean β-parameter. The procedure is general enough to be used in a different setting for SolO, or by a different spacecraft in the future.References:[1] Kvammen, Andreas, et al. "Machine Learning Detection of Dust Impact Signals Observed by The Solar Orbiter." (2022). https://doi.org/10.5194/egusphere-2022-725[2] Kočiščák, Samuel, et al. "Modelling Solar Orbiter Dust Detection Rates in Inner Heliosphere as a Poisson Process." arXiv preprint arXiv:2210.03562 (2022). https://doi.org/10.48550/arXiv.2210.03562
Observation-based assessments of surface flux partitioning regimes in 4 commonly-used land surface models
Authors: He Qing , Lu Hui , Yang Kun
Published: February 2023

Flux partitions between surface water and energy terms are essentially important to the climate system. They can potentially affect assessments of climate risk projections in the future. However, the characterization of surface flux partitioning in numerical models is rarely evaluated due to the absence of large-scale observational evidence. Here, we use long-term satellite datasets and observational meteorological records to evaluate the flux partitioning regime presented in four widely-used Land surface models (LSMs) over two study regions (i.e., China and Continental U.S.). We show that the regime in LSMs differs significantly from satellite-based estimations, which can be due to unrealistic representations of land surface characteristics. The biases in models’ flux partitioning regime may lead to the underestimated potential for climate risks, especially over regions with typical land surface characteristics. The results highlight that particular attention should be paid to the calibration of surface flux partitioning regimes in LSMs. Large model spreads in surface flux partitioning strength and climate risk maps are also reported.
Tides, Internal and Near-Inertial Waves in the Yermak Pass at the Entrance of the Atlantic Water to the Arctic Ocean.
Authors: Provost Christine , Artana Camila , Ferrari Ramiro , Bricaud Clément , Poli Léa , Park Young-Hyang
Published: February 2023

In the crucial region of the Yermak Plateau where warm Atlantic water enters the Arctic ocean, we examined high frequency variations in the Yermak Pass Branch over a 34 months-long mooring data set. The mooring was ice covered only half of the time with ice-free periods both in summer and winter. We investigated the contribution of residual tidal currents to the low frequency flow of Atlantic Water (AW) and high frequency variations in velocity shears possibly associated with internal waves. High resolution modelsimulations including tides show that diurnal tide forced an anticyclonic circulation around the Yermak Plateau. This residual circulation helps the northward penetration of the AW into the Arctic. Tides should be taken into account when examining low frequency AW inflow. High frequency variations in velocity shears are mainly concentrated in a broad band around 12 hr in the Yermak Pass. Anticyclonic eddies, observed during ice-free conditions, modulate the shear signal. Semi-diurnal internal stationary waves dominate high frequency variations in velocity shears. The stationary waves could result from the interaction of freely propagating semi-diurnal internal waves generated by diurnal barotropic tides on critical slopes around the plateau. The breaking of the stationary waves with short length scales possibly contribute to mixing of AW at the entrance to the Arctic.
Paleogeography: a driver for past climate changes?
Authors: Marcilly Chloé , Torsvik Trond H.
Published: February 2023

CO2 is the most important greenhouse gas in the Earth’s atmosphere and has fluctuated considerably over geological time. However, proxies for past CO2 concentrations have large uncertainties and are mostly limited to Devonian and younger times. Consequently, CO2 modelling plays a key role in reconstructing past climate fluctuations.Silicate weathering and subsequent carbonate deposition are widely recognized to compose the primary sink of carbon on geological timescales and are largely influenced by changes in climate, which in turn are linked to changes in paleogeography. The role of paleogeography on silicate weathering fluxes has been the focus of several studies in recent years and mostly aiming to constrain climatic parameters such as temperature and precipitation affecting weathering rates through time. However, constraining the availability of exposed land is crucial in assessing the theoretical amount of weathering on geological time scales. Associated with changes in climatic zones, the fluctuation of sea-level is critical for defining the amount of land exposed to weathering. The current reconstructions used inmodels tend to overestimate the amount of exposed land to weathering at periods with high sea levels. Through the construction of continental flooding maps, we have constrained the effective land area undergoing silicate weathering for the past 540 million years. Our maps not only reflect sea-level fluctuations but also contain climate-sensitive indicators such as coal (since the Early Devonian) and evaporites to evaluate climate gradients and potential weatherablity through time. This is particularly important after the Pangea supercontinent formed but also for some time after its break-up.We here investigate the potential link between land availability dictated by paleogeography and climate changes during the Phanerozoic. Recent studies have shown that continental glaciations occur following periods of decreasing atmospheric CO2, and these periods correspond to peaks in land availability at tropical latitudes. This link tends to attribute such changes to the paleogeographic evolution of our planet but this is not the case for the enigmatic end-Ordovician cooling where the increase in land availability prior to the Hirnantian glaciation appears not to have been enough to counteract the increase in solar energy and initiate cooling.
Modelling the effect of aerosol and greenhouse gas forcing on the Asian monsoons with an intermediate complexity climate model
Authors: Reccchia Lucy , Lucarini Valerio
Published: February 2023

The Asian summer monsoons are globally significant meteorological features, creating a strongly seasonal pattern of precipitation, with the majority of the annual precipitation falling between June and September. The stability of such a strongly seasonal hydrological cycle is of extreme importance for a vast range of ecosystems and for the livelihoods of a large share of the world’s population. Simulations are performed with an intermediate complexity climate model, PLASIM, in order to assess the future response of the Asian monsoons to changing concentrations of aerosols and greenhouse gases. The radiative forcing associated with aerosol loading consists of a mid-tropospheric warming and a compensating surface cooling, which is applied to India, Southeast Asia and East China, both concurrently and independently. The primary effect of increased aerosol loading is a decrease in summer precipitation in the vicinity of the applied forcing, although the regional responses vary significantly. The decrease in precipitation is only partially ascribable to a decrease in the precipitable water, and instead derives from a reduction of the precipitation efficiency, due to changes in the stratification of the atmosphere. When the aerosol loading is added in all regions simultaneously, precipitation in East China is most strongly affected, with a quite distinct transition to a low precipitation regime as the radiative forcing increases beyond 60 W/m2. The response is less abrupt as we move westward, with precipitation in South India being least affected. By applying the aerosol loading to each region individually, we are able to explain the mechanism behind the lower sensitivity observed in India, and attribute it to aerosol forcing over East China. Additionally, we note that the effect on precipitation is approximately linear with the forcing. The impact of doubling carbon dioxide levels is to increase precipitation over the region, whilst simultaneously weakening the circulation. When the carbon dioxide and aerosol forcings are applied at the same time, the carbon dioxide forcing partially offsets the surface cooling and reduction in precipitation associated with the aerosol response.
What are the effects of forests on the hydrological cycle in connection with the changing climate?
Authors: Bolla Bence , Horváth Bálint
Published: February 2023

In the effort to successfully sustain the forests in Hungary: the most important limitation factors are the available water sources and the climate conditions. As the expected effects of the climate change (e.g.: decrease of precipitation in the vegetation period, the increase in frequency of the extreme intensity precipitation events, increase of the length of drought periods, increase of the evapotranspiration due to the mean temperature increase) this will be an increasing challenge to the forest managers in future. The forest stands have an ability to reduce the temperature, increase the humidity and soften the drying effect of the strong wind. So, the protection of our forest stands will become the one of most important tasks in our future. Thus, the research of the interconnection between the forests and the hydrological cycles is an urgent meanwhile difficult task due to the complexity of these systems. Our recent work presents the main conclusions of the recent drought period by our hydro-meteorological system.Acknowledgements:This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.
Conceptual development and use of downscaled climate model information
Authors: Wilby Robert , Dawson Christian
Published: February 2023

Statistical and dynamical downscaling techniques are widely applied in the development of local climate change scenarios. This talk traces the conceptual development of downscaling as a decision-support tool for climate risk assessment, resilience and adaptation planning. Four epochs are identified: (1) early exploration of local changes in key climate variables, such as temperature and precipitation extremes; (2) application of downscaled scenarios to climate impacts modelling (such as for agriculture yield or water resource assessments); (3) advent of ensemble-based methods and more sophisticated handling of uncertainty in the downscaling-impacts workflow; and (4) use of downscaled scenarios to stress-test adaptation options under plausible ranges of climate and non-climatic conditions. Each phase is illustrated by and reflected in the development of the Statistical DownScaling Model – Decision Centric (SDSM-DC) over more than two decades. Questions around fitness for purpose and appropriate uses of the tool are explored. The talk concludes by considering: where next for downscaling?
Estimation of normal and shear compliance for inclined fractures from full-waveform sonic log data
Authors: Zhou Zhenya , Caspari Eva , Barbosa Nicolás D , Favino Marco , Holliger Klaus
Published: February 2023

Fractures are ubiquitous throughout the Earth’s upper crust and represent localized zones of mechanical weakness as well as preferential pathways for fluid flow. Correspondingly, their detection and characterization is vital for a wide range of pertinent applications in geological, civil, and environmental engineering, hydrocarbon exploration, nuclear waste and carbon dioxide storage, as well as geothermal energy production. Particularly important mechanical characteristics of fractures are their normal and shear compliances, which relate the displacement perpendicular and parallel to the fracture plane, respectively, to the corresponding components of the prevailing stress tensor. Based on the linear slip model, previous works developed a phase delay method to estimate the normal compliance of individual fractures using the P-wave first-arrivals in full-waveform sonic (FWS) log data. This approach is viable for a quasi-normal incidence scenario of the sonic wavefield. However, the conditions under which this technique remains valid at oblique P- and S-wave incidence angles as well as the role played by the combined effects of the normal and shear compliances remains enigmatic. To alleviate this problem, we have extended the phase delay technique to allow for non-normally-incident P- and S-waves. In addition to improving the accuracy of the normal compliance estimates with respect to the results computed under a normal incidence assumption, this method allows for a simultaneous estimation of the normal and shear compliances. The proposed approach has been validated through analytical tests and numerical simulations of wave propagation in a hard-rock-type borehole environment intersected by a single fracture with dip angles of 0, 30, and 40 degrees with regard to the horizontal. For fracture compliance values typical of mesoscale fractures (10-14 to 10-12 m/Pa), the effects associated with oblique incidence become significant for dip angles larger than 50 and 30 degrees for P- and S-waves, respectively. However, our results also demonstrate that the normal incidence assumption can produce similar errors at even lower fracture dip angles in the presence of larger fracture compliance values and/or shear-to-normal compliance ratios. Finally, we apply the method to observed FWS data acquired in granitic rocks where the considered boreholes intersect fractures at a range of oblique angles. Direct in-situ estimates of compliances for discrete individual fractures are scarce, but essential to bridge the scale gap between laboratory estimates and input data for reservoir scale models. While recent studies show the feasibility of estimating normal compliances from FWS data, this study aims to explore whether and to what extent this approach can be practically extended to shear compliances and to the corresponding shear-to-normal compliance ratios.
Can earthworms increase inorganic carbon sequestration in an artificial environment?
Authors: Calogiuri Tullia , Hagens Mathilde , van Groenigen Jan Willem , Vidal Alix
Published: February 2023

Enhanced Silicate Weathering (ESW) has emerged as a promising Carbon Dioxide Removal (CDR) technology. However, it is still not clear which factors could maximize ESW rates. Previous studies have shown the potential of soil biota to amplify mineral weathering rates. Among the relevant soil biota are earthworms, which have been found to enhance nutrient release from soil minerals. This is indicative of their ability to increase weathering rates and further inorganic carbon (C) sequestration. Here we aim to accelerate ESW rates in a bio-reactor through earthworm activity. First, we identified the optimal conditions for earthworm survival and activity in an environment exclusively composed of ground silicate rocks and organic substrate. Second, we determined to what extent earthworms can enhance inorganic C sequestration in such a system. We carried out 5 rounds of 2-month experiments in a climate chamber at 25°C. The set-up of the experiments consisted of 200 columns, each topped by a sprinkler connected to an irrigation system, which allowed for different water irrigation rates and watering frequencies. The leachate of each column was collected in a jerrycan kept at 4˚C. Within this set-up, we used two endogeic earthworm species (Aporrectodea Caliginosa and Allobophora Chlorotica) at different densities (10, 20, and 30 earthworms kg-1 soil), three types of rock flours (Basalt, Lava and Dunite) of two grain sizes (0.063 and 1.5 mm), one organic source (straw) and two water irrigation rates (125 and 250 ml day-1 kg-1 soil) at three watering frequencies (1, 2 and 5 times/day). Rock flours were used not only as single type or single size, but also as mixtures of types and/or sizes. At the end of each experiment, we measured earthworm survival and activity, and inorganic C sequestration rates by summing cumulative dissolved inorganic C in the leachate and the newly formed solid inorganic C content. We found no differences in survival and activity between the two earthworm species, but we did find an optimum for both parameters at a density of 10 earthworms kg-1 soil. Earthworms showed a clear preference for a mixture of grain sizes compared to single size, and for single mineral type compared to a mixture of mineral types. The response of earthworm survival and activity to the two water irrigation rates was similar, but at a water irrigation rate of 250 ml day-1 kg-1 soil a frequency of 5 times/day resulted in higher activity. Preliminary results indicate that earthworms increase mineral weathering rates and thereby sequester inorganic C. We demonstrate that earthworms can thrive in a fully artificial environment designed to ESW rates, removing one hurdle for designing a bio-reactor aimed at optimizing carbon sequestration.
HIDRA2: deep-learning ensemble sea level and storm tide forecasting in the presence of seiches – the case of the northern Adriatic
Authors: Rus Marko , Fettich Anja , Kristan Matej , Ličer Matjaž
Published: February 2023

We propose a new deep-learning architecture HIDRA2 for sea level and storm tide modeling, which is extremely fast to train and apply and outperforms both our previous network design HIDRA1 and two state-of-the-art numerical ocean models (a NEMO engine with sea level data assimilation and a SCHISM ocean modeling system), over all sea level bins and all forecast lead times. The architecture of HIDRA2 employs novel atmospheric, tidal and sea surface height (SSH) feature encoders as well as a novel feature fusion and SSH regression block. HIDRA2 was trained on surface wind and pressure fields from a single member of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric ensemble and on Koper tide gauge observations. An extensive ablation study was performed to estimate the individual importance of input encoders and data streams. Compared to HIDRA1, the overall mean absolute forecast error is reduced by 13 %, while in storm events it is lower by an even larger margin of 25 %. Consistent superior performance over HIDRA1 as well as over general circulation models is observed in both tails of the sea level distribution: low tail forecasting is relevant for marine traffic scheduling to ports of the northern Adriatic, while high tail accuracy helps coastal flood response. To assign model errors to specific frequency bands covering diurnal and semi-diurnal tides and the two lowest basin seiches, spectral decomposition of sea levels during several historic storms is performed. HIDRA2 accurately predicts amplitudes and temporal phases of the Adriatic basin seiches, which is an important forecasting benefit due to the high sensitivity of the Adriatic storm tide level to the temporal lag between peak tide and peak seiche.
Nonlinear wave-particle interactions in Whistler-Mode Chorus waves: modulation as a route to rising and falling tones
Authors: Ratliff Daniel , Allanson Oliver
Published: February 2023

Whistler-Mode Chorus (WMC) waves are an important contributor to the dynamics of the magnetosphere, not only for their prevalence in measured observations of near-Earth space but also for their dominant role in transporting energy and particles throughout it. It is therefore of key importance to space weather modelling that we understand how WMC waves are generated, how they subsequently evolve and how they interact with the particle populations that they transport. There are also fundamental physics question to answer as WMC waves display nonlinear phenomena rarely seen in other fields, including their ability to raise and lower their frequency repeatedly and rapidly leading to rising and falling tone waves respectively. Are the interactions between the wave and the particles driving such phenomena, and if so to what degree are they doing so? In this talk, we revisit the nonlinear evolution of WMC waves from a theoretical perspective.  Wave-particle interactions are shown to be a key driver of the modulational instabilities that lead to element and subelement formation which are well represented by an extension of the well-known Nonlinear Schrodinger equation. Simulations of this yields power spectrum reminiscent of the rising and falling tone emissions observed in mission data from the Van Allen probes, THEMIS, MMS and Cluster and determines that that wave-particle interactions are the primary cause of this effect. As a result, this nonlinear theory indicates regimes in which these frequency sweeps can be enhanced or dampened, and suggests why the WMC band gap at half the gyrofrequency exists.
A copula-supported Bayesian framework for spatial downscaling of GRACE-derived terrestrial water storage flux
Authors: Sneeuw Nico , Tourian Mohammad , Saemian Peyman , Ferreira Vagner , Frappart Frédéric , Papa Fabrice
Published: February 2023

The GRACE and GRACE-FO satellite missions have established mass variations as a fundamentally new observation type for a broad spectrum of applications in Earth science disciplines, including oceanography, geophysics, hydrology and hydrometeorology. Despite its innovation and success in hydrology, the utility of GRACE-derived Terrestrial Water Storage Anomaly (TWSA) and its time derivative Terrestrial Water Storage Flux (TWSF) have mainly been limited to large catchments due to their coarse spatial resolution. Here, we propose a method to downscale TWSF and determine its uncertainty within a Bayesian framework by incorporating fine-scale (non-GRACE) data of TWSF and of Soil Moisture Change (SMC) from different available sources. For the Bayesian ingredients, we take GRACE data as the prior and make use of copula models to obtain non-parametric likelihood functions based on the statistical relationship between GRACE TWSF with fine-scale TWSF data and SMC. We apply our method to the Amazon Basin and assess the performances of our products from various fine-scale input datasets of TWSF and SMC. Given the lack of ground truth for TWSF, we validate our results against 2 external information sources: (1) space-based observations of Surface Water Storage Change (SWSC) in the Amazon river system and (2) Vertical Crustal Displacements (VCD) observed by the Global Positioning System (GPS). Overall, the results show that the proposed method is able to estimate a downscaled TWSF, which is informed by GRACE and fine-scale data. Validation shows that our downscaled products are better anticorrelated with VCD (-0.81) than fine-scale TWSF (-0.73) and show a mean relative RMSE of 26% with SWSC versus 70% for fine-scale TWSF. The proposed methodology, although developed in a context of hydrology and of GRACE data, is generic to a high degree. Within hydrology it can be used for other datasets, which are crucial for hydrological application at regional and local scales. Moreover, the methodology can easily be extended to other disciplines in which downscaling of coarse scale datasets is relevant.
Lidar measurements of volcanic aerosol over Mindelo during the volcanic eruption at Las Palmas in autumn 202
Authors: Gebauer Henriette , Baars Holger , Floutsi Athena Augusta , Ansmann Albert , Ohneiser Kevin , Zenk Cordula
Published: February 2023

From 19 September to 13 December 2021, a volcanic eruption took place at Las Palmas, Canary Islands. Thereby, fine ash and volatiles, like SO2, were emitted and transported over hundreds to thousand kilometers away from the island [1]. At the same time, continuous lidar observations with the multiwavelength-Raman-polarization lidar PollyXT were performed at the Ocean Science Center Mindelo (16.878°N, 24.995°W), Cabo Verde, in the frame of the JATAC-campaign 2021/2022. During autumn, typical aerosol conditions over Mindelo, as detected by the lidar, are a clean marine boundary layer up to approx. 1 km and a Saharan dust layer (up to 6 km) above. In the boundary layer, an extinction coefficient of less than 200 Mm-1 and a lidar ratio smaller than 40 sr is typically observed while a lidar ratio between 40 and 60 sr and a depolarization ratio between 20 and 30 % is typically found for the Saharan dust properties. Instead, during the time of the volcanic eruption, a strongly polluted planetary boundary layer (PBL) was observed beginning 23 of September, whereby the extinction coefficient and the lidar ratio increased up to 800 Mm-1 and 60 to 80 sr, respectively. On specific days, the aerosol optical depth, determined by an AERONET sun photometer, was as high as 1.0 (at 500 nm). Due to the small depolarization ratio around 0 % in the PBL and Hysplit trajectories indicating air masses coming from Canary Islands, the observed pollution over Mindelo can be attributed to sulfates emitted by the volcanic eruption at Las Palmas. No indications for volcanic ash over Mindelo were found, neither in the PBL nor in the lofted layer (mainly Saharan dust). This is furthermore supported by Hysplit trajectories, which show that air masses in higher altitudes come from the African continent and not from the Canary Islands. The potential of Aeolus to capture the volcanic plume on its way to Cabo Verde will also be assessed using the aerosol spin-off products (L2A) of the most recently available baseline. References[1] Carracedo, J. C., Troll, V. R., Day, J. M., Geiger, H., Aulinas, M., Soler, V., ... & Albert, H. (2022). The 2021 eruption of the Cumbre Vieja Volcanic Ridge on La Palma, Canary Islands. Geology Today, 38(3), 94-107.
Characterization of ecohydrological indicators (EHIs) in India: a multi-scale perspective
Authors: Bejagam Vijaykumar , Sharma Ashutosh
Published: February 2023

The biogeochemical source and sink dynamics of terrestrial ecosystems play an important role in balance of carbon in the atmosphere. These biogeochemical processes such as carbon, water and energy cycles were affected by climate change and hydroclimatic disturbances. Hence, it is essential to understand the spatiotemporal variations and drivers of different ecohydrological indicators (EHIs) which links the carbon, water and energy cycles. This study assesses the three EHIs, namely water use efficiency (WUEe), rain use efficiency (RUEe), and light use efficiency (LUEe), as well as their drives based on Net Primary Productivity (NPP) in India from 2002 to 2017 at river basin, climatic zone, and land cover scales. All the three EHIs were found to be higher in forest ecosystems which are high productive regions. The mean annual WUEe and RUEe showed a slightly decreasing trend, and the mean annual LUEe experienced a slightly increasing trend. The ecosystem-based study shown that WUEe and LUEe in semi-arid zones and shrubland ecosystems experienced a positive trend. A similar trend was observed in RUEe for arid and shrubland ecosystems. The drivers investigated includes 11variables, CO2 concentrations, evapotranspiration (ET), humidity, leaf area index (LAI), normalized difference vegetation index (NDVI), precipitation (PRECIP), soil moisture (SM), solar radiation (SR), temperature (TEMP), vapor pressure deficit (VPD), and wind speed (WS). TEMP and SR were found to be more sensitive drivers of EHIs. Other drivers such as VOD, SM and humidity also played a significant role in local scales. This study will enhance our understanding of variations in EHIs and their mechanisms which can be a reference in predicting the ecosystem responses and resilience to changing climate and climate extremes.
Enhanced climatology of large hail in the UK: Radar-derived diurnal cycle and storm mode
Authors: Wells Henry , Hillier John , Garry Freya , Dunstone Nick , Chen Huili , Kahraman Abdullah , Keat William , Clark Matthew
Published: February 2023

Large hail, with a diameter of at least 20 mm, is a hazard associated with severe convective storms (SCS) that can cause significant damage. Understanding of atmospheric environments conducive to large hail is underpinned by catalogues of past events. Because of the small footprint of hail events, these often rely on crowdsourced reports. In the UK, the relative rarity of large hail and low public awareness of SCS hazards makes obtaining a complete set of reports difficult, and in many cases the precise time of the hail is not recorded. In this study, the two major databases of UK large hail reports are merged for the first time. Composite radar reflectivity data are used to verify and enhance 260 reports since 2006. Time of the hail and the basic storm mode (isolated, clustered or linear) are visually estimated from animations. Compared to the UK’s most severe historic hailstorms (1800–2004), our quality controlled climatology of all sizes of large hail shows a diurnal cycle with a slightly broader peak. Around 55% of large hail events are associated with isolated cells, while 34% have supercellular characteristics, a much lower proportion than found in the USA. The full event set (1979–2022), comprising over 850 reports, is used to update the seasonal, spatial and size distributions of large hail in the UK. We intend that this hail event set forms part of a multi-hazard analysis of UK SCS, also including tornadoes and extreme rainfall, and its relationship to background atmospheric conditions. The effect of climate change on UK SCS will be investigated through past and future trends in these background conditions.
Influence of sources in the generation of silicic rocks of the Deccan Traps Continental Flood Basalt
Authors: Halder Mahesh , Paul Debajyoti , Yang Shouye
Published: February 2023

Complex petrogenetic processes involving multiple sources may account for the presence of silicic rocks (SiO2 >65 wt%) in Continental Flood Basalts (CFBs). Here, we use a holistic framework involving field observations, petrography, major oxides (n = 56), and trace element chemistry to examine eight scattered but significant silicic rock exposures found within the 65.5-66 Ma old Deccan Traps CFB. Rhyolite and granophyre with subordinate felsite, ignimbrite, trachyte, pitchstone and microgranite coexist with basalt, basaltic andesite, and gabbro. Thermodynamic-based Rhyolite-MELTS modelling suggests that the major oxide composition of associated basalt is a likely candidate for the parental melt composition of the silicic rocks of the Deccan Traps. Two broad REE patterns are noticed in the Deccan Traps silicic rocks; a flat pattern for Barda, Alech, and Chogat-Chamardi silicic rocks, and a steep REE pattern for Osham, Rajula, Pavagadh, Rajpipla, and Bombay silicic rocks. Basalt from Barda (La/LuN = 3.57) and Pavagadh (La/LuN = 11.0) display similar flat and REE patterns observed in the associated silicate rocks. Trace element modelling reveals that partial melting at different depths (shallow vs. deeper) from lherzolite sources and subsequent extensive fractional crystallization (50-90%) of these two parental mafic melts could generate the trace element composition of the Deccan Traps silicic rocks. The geochemical variability of Deccan Traps silicic rocks reveals an origin mostly from a mantle source with contributions of continental crust at a later stage, which is typical of silicic volcanism in other global CFBs.
Hot-spots of denitrification in soil depending on crop residue and liquid manure incorporation – models and experiments
Authors: Well Reinhard , Dechow Rene , Grosz Balazs
Published: February 2023

Soil denitrification is known to be affected by incorporation of crop residues due to supply of reductants and oxygen (O2) consumption by decomposition. The formation of anoxic microsites where denitrification can occur thus depends on quality, particle size and spatial distribution of incorporated residues in interaction with physical and chemical soil properties. Current biogeochemical models typically assume homogeneity of soil layers and thus don’t consider the size and distribution of crop residue particles. Until now, dinitrogen (N2) and nitrous oxide (N2O) fluxes related to residue incorporation patterns have been rarely studied and are poorly represented by current models. Here we present synergetic concepts and results of two projects addressing the spatial modelling of anoxic hot-spots („Modeling the impact of liquid organic fertilization and associated application techniques on N2O and N2 emissions from agricultural soils”, MOFANE) and measures to mitigate denitrification in soil („Measures to reduce direct and indirect climate-impacting emissions caused by denitrification in agriculturally used soils”, MinDen).To test the incorporation of harvest residues and catch crops on denitrification, a full-factorial laboratory incubation will be carried out in MinDen, assessing incorporation methods and pre-crushing of catch crops, and how these interact with soil type and water content. Based on a static model to take into account spatial hot-spots induced by liquid manure (Baral et al., 2016)  a dynamic model was developed in MOFANE and tested using lab experiments (Grosz et al., 2022). This model can also be applied to evaluate the aforementioned crop residue effects.We present a conceptual model of denitrification in dependence of size and distribution of crop residues, soil type, soil moisture and soil structure. It predicts that pre-shredding and homogenous incorporation favours denitrification at low gas diffusivity given by high moisture and/or high clay content or bulk density, since small organic hot-spots suffice to create anoxia. For high gas diffusivity (e.g. due to sandy texture and/or dry conditions) it predicts that denitrification is favoured if incorporated crop residues are large, since anoxic microsites can only develop if the size of organic hot-spots is large enough so that the O2 sink strength exceeds O2 diffusion from the atmosphere.Scenarios of the conceptual model will be tested using the dynamic hot-spot model and results will be presented. Baral, K.R., Arthur, E., Olesen, J.E., Petersen, S.O., 2016. Predicting nitrous oxide emissions from manure properties and soil moisture: An incubation experiment. Soil Biology & Biochemistry 97, 112-120.Grosz, B., Kemmann, B., Burkart, S., Petersen, S.O., Well, R., 2022. Understanding the Impact of Liquid Organic Fertilisation and Associated Application Techniques on N2, N2O and CO2 Fluxes from Agricultural Soils. Agriculture 12, 692.