bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron-scale dynamics and generalized Ohm’s law of an MMS X-line encounter on 27 August 2018
Authors: Li Wenya , Tang Binbin , Wang Chi
Published: February 2023

Magnetic reconnection is a fundamental process in collisionless space plasma, and the electron-scale kinetic physics at the X line controls how the magnetic field lines break and reconnect. The four spacecraft of the Magnetospheric Multiscale (MMS) mission encountered an X line of symmetric reconnection in the terrestrial magnetotail on 27 August 2018. Here, we present the electron-scale dynamics and the generalized Ohm’s law (GOL) analysis of this case. Its two-dimensional structure, magnetic topology, and electron streamline map are reconstructed based on a time-independent and inertialess form of electron magnetohydrodynamic (eMHD) equation. We map the electron velocity distribution functions (VDFs) along the MMS trajectories through the X line, covering the two-side inflow and reconnected regions, and the typical electron motions for forming the observed VDFs are also presented. The observed reconnection electric field EM is approximately 2-3 mV/m and predominantly balanced by the spatial gradient of the electron pressure off-diagonal term PeMN, which is mostly contributed by the electron meandering motion at the X line. Our results show the electron-scale dynamics and the associated electron VDFs at an X line and their role in the electron force balance.
Effect of the fertiliser supply for the maize micro nutrient content depending on the part of the plants under long-term field experiment
Authors: Illés Árpád , Bojtor Csaba , Kakuszi-Széles Adrienn , Horváth Éva , Nagy János
Published: February 2023

The long-term experiment was carried out at the University of Debrecen, Institutes for Agricultural Research and Educational Farm, Debrecen Edcuational Farm and Landscape Research Institute (DTTI), Látókép Crop Production Experiment Site (47° 83, 030" N, 21° 82, 060" E, 111 m a.s.l.). The experimental area is an excellent site for field crop production, with suitable agrotechnical biological and soil conditions. The trial was established in 1983 by Prof. Dr. János Nagy and has been continued for 39 years with the same parameters, nutrient replenishment system, site, tillage and agrotechnology. The total area of the experiment is more than 1.3 ha, with 1248 plots. The climatic-meteorological conditions of the experimental area are continental and often extreme, with calcareous chernozem soil with a topsoil depth of 80-90 cm and a humus content of 2.71 Hu%. The pH of the soil is 5.76 (slightly acidic). The soil is less susceptible to acidification because the 80-90 cm deep calcareous layer is a good buffer against acidification. In terms of soil acidification, nearly 40 years of high-dosage nitrogen fertilization (300 kg/ha of active ingredient) in the experiment resulted in a pH decrease of only 0.6 units compared to the control.  For this study, nitrogen doses of 0-300 kg/ha were applied at 5 different levels, with a gradual increase in nitrogen and a constant high level of phosphorus and potassium. In a micronutrient uptake effect study of nitrogen fertilisation, it was found that the concentration of zinc, the primary essential micronutrient for maize, was significantly reduced in all crop parts by increasing nitrogen dosage compared to control values. The most significant of these effects was the reduction in stalk zinc concentration in the vegetative parts of the crop, which was at least 39% in all treatments, with the greatest reduction in treatment N4 at 18.61 mg/kg.  In the case of the generative parts of the plant, the zinc content of the grain yield decreased statistically in all treatments, with the greatest negative change in this case also in treatment N4, with a decrease of 39 % (9.14 mg/kg). The iron content responded positively to the increase in nitrogen fertilisation. An increasing trend was measured for all plant parts, which was significant in several cases. Significant increased iron accumulation was observed during the leaf analysis of maize under all fertiliser treatments, with the highest increase of 47 % under the treatment N5. Based on the correlation between copper content and nitrogen supply in plant parts, it was found that increasing nitrogen fertiliser treatments resulted in significant increased concentrations in both maize leaves and cobs, ranging from 5 to 56 % and 8 to 38 %, respectively. The values obtained from stem and grain yield analyses did not show significant changes in effect.
Mapping Drained Lake Basins on a circumpolar scale
Authors: Bergstedt Helena , Jones Benjamin , Bartsch Annett , Farquharson Louise , Wolter Juliane , Breen Amy , Kanevsiy Mikhail , Grosse Guido , Roy-Léveillée Pascale , von Baeckmann Clemens
Published: February 2023

Lakes and drained lake basins (DLB) are ubiquitous landforms in permafrost lowland regions, covering 50% to 75% of permafrost lowlands in parts of Alaska, Siberia, and Canada. Depending on the time passed since the drainage event, surface characteristics within the DLB such as surface roughness, vegetation, moisture and abundance of ponds may vary. The mosaic of vegetative and geomorphic succession within DLBs and the distinct differences between DLBs and surrounding areas can be discriminated with remote sensing and used to derive a landscape-scale classification. Previously published local and regional studies have demonstrated the importance of DLBs regarding carbon storage, greenhouse gas and nutrient fluxes, hydrology, geomorphology, and habitat availability. To help quantify these processes on a circumpolar scale and improve the representation of Arctic landscapes in large scale models, a circumpolar data set of DLBs distribution and DLB properties is needed.  Due to the inherent temporal characteristics of DLBs, such a data set also has the potential for space-for-time applications regarding landscape models. A pan-Arctic scale effort to map and further the understanding of DLBs in permafrost-regions is the outcome of work conducted within the International Permafrost Association (IPA) Action Group on DLBs, a bottom-up effort led by the scientific community that includes developing a first pan-Arctic drained lake basin data product based on multispectral remote sensing data (Landsat-8). Comprehensive mapping of DLBs areas across the circumpolar permafrost landscape and including field data into this approach will allow for future utilization of these data in pan-Arctic models, aid upscaling efforts and greatly enhance our understanding of DLBs in the context of permafrost landscapes. This will improve quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, high-latitude carbon cycling, and landscape vulnerability to climate change.
The regular solar wind impact on the high-latitude electron density in time scales of days and weeks
Authors: Borries Claudia , Davies Fredy , Iochem Pelin , Tasnim Samira , Vogt Joachim
Published: February 2023

Global changes in the state of the ionosphere-thermosphere system depend to a large extent on the energy input from the solar wind and magnetosphere, which occurs in the high-latitude regions. On the one hand energy is deposited in the form of Joule heating causing changes in the thermosphere composition and circulation. On the other hand, imposed electric fields change plasma transport. Joule heating is closely related to changes in the solar wind dynamic pressure, because it can cause a compression of the magnetosphere driving currents in the magnetosphere, and the currents transfer electromagnetic energy into the ionosphere. The enhancement of plasma convection in the polar ionosphere is related to the intensification of the convection electric field, which is driven by the solar wind sweeping across the open magnetic field lines of the polar magnetosphere. These changes are most significant during storm conditions, caused e.g. by coronal mass ejections and corotating interaction regions. The storm related energy release in the high-latitude ionosphere is impacting the thermosphere-ionosphere system on a global scale.However, the solar wind impact causes a regular every day variability of the polar ionosphere, too. We are investigating how the solar wind variability in time scales of days and weeks is reflected in the ionosphere variability at Tromso, which is located in Scandinavia at 70°N, 19°E. We use cross correlation analysis of total electron content with solar wind merging electric field and dynamic pressure data. It can be shown that in timescales of days and weeks, the magnitude of correlation between TEC and solar wind reaches similar values to the correlation of TEC and F10.7. However, the results show that the correlation between TEC and solar wind parameters depends strongly on local time, season and solar cycle. There is a clear annual cycle in the variability of the correlation coefficient, with higher correlation values in winter than in summer. The positive correlation in winter close to local midnight hours is related to precipitation effects increasing the electron densities. During summer in solar maximum condition, clear negative correlation values are retrieved. These are considered to be caused by increased convection.
A numerical study of tearing instability growth rate as a function of current sheet thickness in the kinetic regime
Authors: Innocenti Maria Elena , Pucci Fulvia , Boella Elisabetta , Tenerani Anna , Dargent Jeremy
Published: February 2023

In this study, we use fully kinetic Particle In Cell (PIC) simulations to investigate numerically the dispersion relation of the tearing instability in the kinetic regime, which is at the moment rather poorly explored by theoretical investigations. To reduce the computational cost of the simulations, we use the the semi-implicit, energy conserving ECsim code (Lapenta et al, 2017), that allows us to step over the smaller scales and fastest frequencies and focus on characteristic scales of interest, with excellent energy conservation.We run several simulations with current sheets of fixed length. The current sheet half-thickness is progressively increased from $\delta \sim d_i$ to significantly larger. The other simulation parameters are kept identical.In our simulations, the tearing instability grows without external perturbation from the particle noise of PIC simulations. Later onset times are (predictably) observed when the number of particles per cell is increased.Several modes grow unstable in each simulation. We plot the growth rates of the unstable modes as a function of the current sheet thickness. We obtain a spread around a curve decreasing with increasing current sheet thickness. 
The Sensitivity of Moisture Fluxes into the Tropical Tropopause Layer to External Forcing
Authors: Kroll Clarissa , Fueglistaler Stephan , Kornblueh Luis , Schmidt Hauke , Timmreck Claudia
Published: February 2023

The very low temperatures in the tropical tropopause layer (TTL) restrict the moisture entering the stratosphere, leading to its dryness. Whereas the water vapor flux into the stratosphere can be described via the cold point temperatures, our knowledge on the contribution of frozen moisture to the total flux is incomplete. This raises concerns regarding the ability of General Circulation Models (GCMs) to accurately predict changes in total stratospheric moisture following perturbations in the radiative budget due to volcanic aerosol or stratospheric geoengineering, as GCMs  heavily rely on convective parameterizations. The emerging cloud-resolving simulations, however, offer the unprecedented possibility to gain insight into the sensitivity of a TTL, which is not strongly constrained by parameterized convection. Here we present the first results using global convection-resolving simulations to investigate the sensitivity of moisture fluxes within the TTL to an additional heating source. We address the question of how the partitioning of moisture fluxes into water vapor and frozen hydrometeors changes under perturbations. This study shows an exceptional resilience of the TTL, keeping the flux partitioning constant - even at an average cold-point warming exceeding 8 K. In the perturbed and unperturbed simulation, frozen moisture contributes around 20 % of the moisture flux into the stratosphere.
Pre- and post-fragmentation conditions during the 1999 Vulcanian activity at Guagua Pichincha volcano (Ecuador) revealed by textural analysis of breadcrust bombs
Authors: Colombier Mathieu , Wright Heather , Manga Michael , Bernard Benjamin , Samaniego Pablo , Cáceres Francisco , Vasseur Jeremie , Jakata Kudakwashe , Dingwell Donald
Published: February 2023

Breadcrust bombs are typical products of Vulcanian eruptions. The exteriors of such pyroclasts experience rapid quenching after fragmentation and hence preserve a dense crust with no or limited textural change. The core of breadcrust bombs can instead stay above the glass transition temperature for a long time and evolve texturally as vesicles nucleate and grow. Breadcrust bombs are thus key pyroclasts that provide information about (i) pre-eruptive textural, chemical, and pressure conditions in the conduit at the time of fragmentation, (ii) the link between radial cooling history of the bomb and dynamics of bubble formation and (iii) transition from closed- to open-system degassing in natural magma at near-atmospheric pressure and in the presence of variable amounts of crystals. We analyzed two breadcrust bombs from 1999 Vulcanian activity at Guagua Pichincha volcano, Ecuador, previously described by Wright et al. (2007). We performed a quantitative textural analysis along radial profiles from the exterior surface to the interior of the bombs in two dimensions using Scanning electron microscopy, and in three dimensions using synchrotron-based X-ray micro-tomography. This analysis yielded the porosity and vesicle number density change with radial distance. We coupled this textural analysis to a model of viscosity, bubble growth rate and diffusion timescales to shed light on the timing of vesiculation and cooling across the rim to core profile. Our results revealed three vesicle populations: (i) a pre-existing population of large vesicles with a low vesicle number density that was formed prior to fragmentation, (ii) a halo of small and isolated, syn-eruptive vesicles with high vesicle number density formed around these large vesicles in the crust and (iii) vesicles that did not have time to form in the crust and nucleated and grew after fragmentation in the initially vesicle-free groundmass towards the core. We interpret these textures in the light of pre-eruptive conditions in the conduit prior to Vulcanian eruptions preserved in the crust and post-fragmentation vesiculation and transition from closed- to open-system degassing in the core.
Coastal circualtion over the Gulf of Cadiz continental shelf. Local vs remote effects.
Authors: Sirviente Sara , Bolado-Penagos Marina , Gomiz-Pascual Juan Jesús , Bruno Miguel
Published: February 2023

Studies about the coastal circulation over the northern continental shelf of the Gulf of Cadiz, based on current velocity observations, were published on relatively recent dates (e.g., Relvas and Barton, 2002). Since then, a considerable number of articles have been written dealing with this subject up to the present date (e.g., Oliveira et al., 2022). One of the most studied features in these studies are the so-called Coastal Counter Currents (CCCs) in the coastal shelf. These features are located roughly between the 100 m isobath and the coastline, and they are directed toward west. Nevertheless, despite the considerable number of articles devoted to the analysis of this phenomenon, the actual along-coast extension and origin of these CCCs remain unclear.In the present contribution different mechanisms that have been already proposed to explain the development of these CCCs are revised and discussed. For this purpose, an analysis based on surface currents derived from High Frequency Radar (HFR) and numerical model simulations has been carried out.  The most interesting finding is that the most intense CCCs events are initiated on the coastal margin of the westernmost side of the Strait of Gibraltar, and they are extended further west of Cape Santa Maria. Also, these intense and extensive CCCs are triggered by the joint action of local winds over the Gulf of Cadiz and additional remote effects. This study highlights the importance of different remote effects: (i) the wind forcing over the Alboran Sea and the easternmost side of the Strait of Gibraltar, and (ii) the sea level atmospheric pressure forcing over the Ligurian Sea. This mechanism has been demonstrated from both statistical analysis and numerical experiments which allow us to understand the coupling between the horizontal and transverse pressure gradients, causing a geostrophic adjustment of the current against the coast.References.De Oliveira- Junior, L., Relvas, P., Garel, E. Kinematics of surface currents at the northern margin of the Gulf of Cádiz. Ocean Science,18,1183-1202,2022.Relvas, P., and Barton, E. D., Mesoscale patterns in the Cape São Vicente (Iberian Peninsula) upwelling region, J. Geophys. Res., 107( C10), 3164, doi:10.1029/2000JC000456, 2002.  
Evolution of Rockfall based on SfM reconstruction of Street View and UAV data: Case study Kotopanjang, Indonesia
Authors: Choanji Tiggi , Fei Li , Wolff Charlotte , Wang Jing Jing , Yuskar Yuniarti , Derron Marc-Henri , Jaboyedoff Michel
Published: February 2023

In regions where rockfall in a constant occurrence, understanding rockfall evolution becomes essential. Accurate information on the quantity of rock that happens can be obtained through historical data or primary data that can be compared between the two. The Koto Panjang area is a small local mine that is quite risky because it is on the side of the main road connecting access to the two provinces. This area is geologically included in Bohorok Formation composed of gravelly mudstone deposited during the Carboniferous - Early Permian period. Three rockfalls occurred in this area in 2015, 2016 and 2016, closing access for passing vehicles. To obtain historical data comparison, 164 images of data were collected from 360 street view panoramas ranging from 2015 - 2021. The data were extracted and converted into cube images using the decompose equirectangular panorama method, and then the images were processed using Agisoft to create point clouds and compared with the latest UAV data. Based on the comparison results, it was found that significant changes of up to 4,400m3 from 2015 to 2021 occurred at several points along this area. Kinematic structure analysis from direct measurement and 3D point cloud also showed the rockfall area predominantly with direct toppling and wedge failure, which caused the previous rockfall. Therefore, this method can help reconstruct area that have experienced rockfall and provide an understanding of the retreat evolution of rockfall in the area.
4D reconstruction of the Aar Massif during the late-stage continent-continent collision in the European Alps
Authors: Musso Piantelli Ferdinando , Nibourel Lukas , Berger Alfons , Herwegh Marco
Published: February 2023

Inversion and exhumation of crystalline basement units of passive margins is a critical stage of mountain-building processes. With a multi-methodological approach that combines 3D geological modelling and cross-section restoration at different time steps, we unravel the 4D geodynamic evolution of the Aar Massif (central Alps, Switzerland) during the late-stage Alpine orogeny (22 to 0 Ma). Our results demonstrate how a portion of the crystalline basement units of the European continental margin was exhumed in a non-cylindrical framework with an alternation of vertical and horizontal-dominated tectonics. Rapid exhumation (22 to 12 Ma), with deformation along steep reverse/normal faults, alternated with northwest-directed thrusting of the previously exhumed basement units (16 to 0 Ma). We pay special attention to how shear/fault zone patterns change laterally and temporarily to accommodate the non-cylindrical deformation in dome-like basement rises. Published thermochronometric and metamorphic peak temperature data provide additional insights into the temporal sequence of reverse and thrust faulting perpendicular and parallel to the strike of the orogen. Such variations in the fault geometries and associated offsets were constrained by the detailed reconstruction of the shear zone pattern in 3D. In this study, we show how the basement-involved uplift and shortening controlled the late-stage collisional overprint and mechanics of the northern rim of the central Alps.
The Influence of Surface Buoyancy Flux and Ekman transport on Upper Ocean Pycnocline Stratification in the Southern Ocean.
Authors: Caneill Romain , Roquet Fabien , Madec Gurvan , Nycander Jonas
Published: February 2023

In this study, we examine the factors that influence upper ocean pycnocline (UOP) stratification in the Southern Ocean. The UOP is a layer located just below the mixed layer and its stratification controls the rates of exchange of heat, carbon, and nutrients between the ocean interior and the atmosphere. We classify regions of the UOP based on the relative roles of temperature and salinity in stabilizing the layer, resulting in alpha (temperature-stabilized), beta (salinity-stabilized), or transition (temperature and salinity-stabilized) zones. Our analysis uses observation profiles from the EN4.2 database and calculates annual mean buoyancy fluxes by combining existing heat and freshwater flux products and accounting for the effect of Ekman transport. Our results show that the polar transition zone has a complex structure, with interlocking beta pools and local intrusions into alpha zones. Deep mixed layers are found in the southernmost flank of the alpha region, with the exception of the southeast Pacific sector where they are located in the polar transition zone. Regions of negative buoyancy flux show mixed layer deepening along the water path, but deep mixed layers only form when the buoyancy flux is negative throughout the path. Ekman transport contributes also to the formation of deeper mixed layers throughout the Southern Ocean by bringing cold water northward. Overall, our findings reveal that boundaries between alpha, transition and beta regions are generally consistent with more traditional frontal definitions and provide a comprehensive view of upper ocean pycnocline stratification in the Southern Ocean.
How unexpected was the Spring 2022 South Asian Heatwave
Authors: ul Hassan Waqar , Ahmad Nayak Munir
Published: February 2023

Persistent heatwaves cause severe impacts on the ecosystem and society, including increased mortality, and widespread snow and glacier melting. These impacts are expected to escalate in a warmer world, which is likely to witness more frequent and intense heatwaves. South Asia (SA), home to one-fifth of the global population and the largest freshwater resource on the earth, is a hotspot of extreme heatwaves and vulnerable to severe impacts. The region recently experienced its hottest March and April of the century in the year 2022. Here, we use high-resolution, long-term ERA5 (1959–2022) and CPC (1979–2022) data to show that the temperatures in Northwestern South Asia were about 5°C higher than the climatology, which corresponds to about 2.5 standard deviations above the mean. Using maximum temperature-based CTX90pct definition of heatwaves, we show the 42-day-long heatwave in the month of March and April 2022 ranked the most severe heatwave recorded in the available observation period of 65 years. The heatwave engulfed half of Northwest SA, approximately 1.6 million km2, with an average intensity of 1.8°C. The high-temperature driven snow melting during the heatwave nearly vanished the year’s snowpack, which normally lasts till June. With further analysis, we find that the heatwave was initiated by a persistent anticyclonic blocking associated with a sub-tropical Rossby wave, while it was exacerbated by strong positive land-atmosphere feedback due to lack of soil moisture and latent heat. Our findings provide valuable insights into understanding the changes and impacts of heatwaves in the mountainous areas of SA.
High spatial resolution retrieval of cloud droplet size distribution from polarimetric specMACS observations and application to simulated data
Authors: Pörtge Veronika , Kölling Tobias , Weber Anna , Volkmer Lea , Emde Claudia , Zinner Tobias , Forster Linda , Mayer Bernhard
Published: February 2023

We present novel remote sensing observations of cloud droplet size distributions retrieved from polarimetric observations of the wide-field airborne imaging system specMACS. The measurements were collected during the EUREC4A field campaign which took place in January and February 2020 in the trade wind region east of Barbados. We focus on observations of the cloudbow which is an optical phenomenon that results from single scattering of sunlight by liquid droplets close to the cloud top. The cloudbow signal strongly depends on the cloud droplet size distribution. By fitting model simulations (stored in a look-up table) to the cloudbow observations, both the effective radius and the effective variance (i.e., the width) of the droplet size distribution are retrieved. Traditional retrieval techniques based on total reflectance measurements are able to determine the effective radius but do not provide information on the effective variance. However, to fully understand cloud growth processes and the interaction between clouds and solar radiation, both parameters must be known. Furthermore, the cloudbow is only weakly affected by 3-D radiative transfer effects which is beneficial since these are usually a problem for traditional methods.High-resolution maps of the cloud droplet size distribution with a spatial resolution of 100 m by 100 m are presented. The maps reveal patterns within the cloud droplet size distribution at cloud top that could originate from mechanisms like entrainment or mixing processes. We further show first results of an application of the retrieval to simulated specMACS observations. The images were generated using the 3-D radiative transfer model MYSTIC and are based on realistic LES cloud field simulations. We will investigate limitations and uncertainties of the retrieval using the simulated dataset.
Spatial variability of Carbon turnover in soil microaggregates and the challenge of combining multi-scale approaches
Authors: Meyer Nele , Kaldun Jacqueline , Rodionov Andrey , Amelung Wulf , Lehndorff Eva
Published: February 2023

The long-term stability of soil organic carbon (SOC) is controlled by stabilization mechanisms, among which physical stabilization through microaggregate (<250µm) formation is considered to be critically important. Yet, the turnover of Carbon in aggregates is not well understood. Here, we aimed at unravelling the importance of microaggregates for long-term C storage in a soil subjected to a C3-C4 vegetation change 36 years before sampling. We hypothesized that Carbon in microaggregates is characterized by a longer mean residence time (MRT) than that of bulk soil and that SOC turnover appears predominantly at the outside of aggregates. Free and occluded size fractions (250-53 µm) were obtained by wet sieving and ultrasound. True aggregates were manually isolated from size fractions and analyzed for quantity, C content, and bulk δ13C. Additionally, we used laser ablation isotope ratio mass spectrometry (LA-IRMS) with a resolution of 20 µm to study small-scale patterns of δ13C within aggregates and on their surfaces. The calculated MRT of Carbon in occluded and free aggregates was with 62 and 105 years only slightly longer than that of bulk soil (58 years). Also the low quantity of true aggregates (<5% aggregates in size fraction) questions their importance for soil C storage. The spatial variability of δ13C within individual aggregates was considerable, both in C3 (-18.8±6.4) and C4 (-19.6 ±5.5) soil, but without difference between inside and surface locations. No aggregates being clearly older than 36 years, i.e. with only C3-derived SOC isotope signatures were found, suggesting that on the micro-scale microbial turnover processes control δ13C more than expected. In summary, aggregates seemed to be subjected to high rates of formation and decay. Altogether, it is therefore questionable whether aggregates considerably contribute to overall long-term SOC storage. Yet, results need to be treated with caution and we will present evidence that the concept of source mixing between C3 and C4-derived Carbon is not valid in small-scale approaches where differences in δ13C are dominated by C turnover processes rather than source.
Prevalence and drivers of abrupt shifts in global drylands: gathering dynamical evidences of aridity thresholds
Authors: Berdugo Miguel , Delgado-Baquerizo Manuel , Guirado Emilio , Gaitan Juan J. , Fournier Camille , Crowther Thomas W. , Dakos Vasilis
Published: February 2023

Drylands occupy 45% emerged lands on Earth, are home of more than 2 billion people and are extremely vulnerable to climate change. Aridity increases is expected to influence the structure and functioning of drylands in a non-linear fashion. Yet, the prevalence and drivers of these abrupt changes in ecosystem structure and function remain poorly studied. We especially lack investigations of the changes of dynamical properties of these systems and how these dynamical properties relate to aridity. Those are key to understand the real menace of experiencing abrupt shifts with aridity increases in the near future.Here we used remote sensing tools to acquire dynamical trajectories of normalized vegetation indices (NDVI, surrogates of plant fractional cover) for more than 50,000 dryland sites. With this information we conducted analysis using machine learning processes to examine the relationship of aridity with some key dynamical properties of dryland ecosystems, including several aspects of resilience (ability to withstand fluctuations without changing the functioning of ecosystems), dynamical drivers of productivity, complexity of dynamical trajectories and abruptness of productivity changes.By doing so we provide a comprehensive assessment of aridity thresholds on dynamical properties of dryland productivity that show clear vulnerability of certain zones of the Earth exhibiting critical aridity thresholds previously identified through space. In particular, we show accumulation of abrupt shifts on aridity values characteristic of transition areas from semiarid to arid ecosystems. Furthermore, these values exhibit also nonlinear shifts in resilience of ecosystems and on the identity of key dynamical drivers. Our work paves the way to expand the incidence of aridity threshold from spatial to temporal implications, and highlights the necessity of developing strategies to protect and monitor especially vulnerable areas affecting more than one fifth of emerged lands.
Tracing soil respiration and its source across tropical peatland microtopographies and vegetation covers
Authors: Sasmito Sigit , Taillardat Pierre , Moore Jared , Cahya Muhardianto , Alfina Tiara , Fong Letisha , Lok Sophie , Ren Jonathan , Tarigan Suria , Taufik Muh , Mulyadi Dedi , Taylor David , Lupascu Massimo
Published: February 2023

Soil respiration (CO2 effluxes) is a critical component for land-based greenhouse gas (GHG) monitoring, reporting and modelling. In organic matter-rich tropical peatlands, soil respiration magnitudes and variability are driven by belowground live root density (autotrophic) with substantial contribution of peat oxidation via microbial activity (heterotrophic). Moreover, other seasonally characterised environmental factors affect soil respiration dynamics such as hydrological condition, temperature and soil moisture. Yet, the respective contribution of autotrophic and heterotrophic to total soil respiration may vary between sites, vegetation covers, and microtopography profiles in tropical peatlands, leading to GHG reporting uncertainty. Clarifying the contribution heterotrophic activity will therefore provide a better understanding of the effect of peatland restoration or drainage on soil CO2 effluxes reduction or increase, respectively. Here, we present and discuss soil respiration measurements taken across two different microtopography (hummock and hollow) and three land covers (natural forest, retired Acacia plantation, and shrubland) in tropical peatlands of Tri Pupa Jaya, South Sumatra, Indonesia over wet and dry seasons of 2022. We used a trenching approach (live root free peat plot) and complementary with carbon stable isotope (13C-CO2) sampling across 27 paired measurement plots to determine the proportion of their autotrophic and heterotrophic contributions. Our preliminary findings suggest that autotrophic and heterotrophic soil respiration substantially vary across plots located in the hummock compared to hollow microtopography, with higher soil respiration observed at hummock compared to hollow microtopography, suggesting dominant root distribution forming higher elevations and generating higher autotrophic respiration in the hummock microtopography. Soil respiration from the trenched plots, was typically lower by 14–42% compared to untrenched plots and this pattern is consistent with the carbon stable isotope signatures. This study will help improve the current understanding of the driving mechanism and factors controlling magnitudes of soil respiration in tropical peatlands, particularly in assessing the impacts of both peatland restoration and drainage toward soil CO2 efflux dynamics.
The Hot Spot analysis of Land use and Land cover changes (LULCC) in South Korea and North Korea
Authors: Kim Whijin , Lee Woo-Kyun
Published: February 2023

Land use and land cover changes (LULCC) as a part of ecosystems has a significant impact on carbon budget. According to IPCC, approximately 23% of carbon was emitted from the human activities in agriculture, forestry and other land use (AFOLU) from 2007 to 2016. However, land cover includes crucial sector for carbon stock, as well. The land cover consists of five categories which are used area, agricultural land, forest, grass, wet land, and barren. Among these categories, forest counts because of its capacity of carbon sequestration. It is essential to manage the land use and land cover changes effectively since it has lots of influences on carbon cycles. Also, the sustainable management of land use and land cover changes could contribute to reducing the carbon emissions such as preventing deforestation and revegetation. Therefore, this study aims at analyzing the frequent land use change region using hot spot analysis in South Korea and North Korea and estimating the carbon emission and removals from land cover changes. First of all, we tracked the land cover changes at 10 years interval from 1980s to 2010s and identified the general trends. The changed area and ratio of each land cover were varied in both countries, but they had similar characteristics which is land cover changes from forest to cropland and from cropland to forest. It occurred for last four decades. To define the which region has been changed, the hot spot analysis was utilized. The change from forest to cropland appeared in southwest region of North Korea, major agriculture land. On the other hand, the transition from agriculture land to forest seemed to be minor, but the distinguished figure was created during the 2000s to 2010s change. The carbon emission was estimated at the hot spot area and these repeated changes led to additional carbon emission. This study would contribute to preventing the land cover changes frequent by defining the region to be managed.
Dynamics of biological ice nucleating particles during a phytoplanktonic bloom in the Arctic
Authors: Wieber Corina , Jensen Lasse Z. , A. Ferreira A. Sofia , Vergeynst Leendert , Finster Kai , Šantl-Temkiv Tina
Published: February 2023

With raising temperatures in the Arctic, the extent of sea ice is decreasing dramatically resulting in a larger fraction of the Arctic ocean surface being exposed to the atmosphere. Therefore, the ice-free ocean and in particular the sea surface microlayer (SML), which represents the upper 1 mm of the water column is becoming of increasing interest as a source of bioaerosols with ice nucleating properties. These biological ice nucleating particles (INPs) can be aerosolized by wave breaking and bubble bursting. In the atmosphere, they may trigger the freezing of cloud droplets and thus affect the lifetime of clouds as well as their radiative properties. Recent studies proposed a link between biological ice nucleating aerosols in the Arctic sea water and phytoplanktonic blooms.Thus, we examined the concentration and characteristics of INPs in both, the sea bulk water, and the surface microlayer for two locations in southwest Greenland throughout a phytoplankton bloom. Further, we investigated possible links between INP concentrations in the sea water, the abundance and community composition of bacteria and algae, as well as the phytoplanktonic growth season derived from satellite data and in-situ chlorophyll concentrations. Preliminary results will be presented. 
Auroral dripping and its possible magnetospheric source
Authors: Wang Wenrui , Yang Jian , Zhang Fei
Published: February 2023

We have recently discovered a new auroral structure called "auroral dripping" with ground-based and magnetospheric conjugated observations. They are frequent drippings from higher latitudes toward the equator, with a duration of 10-20 minutes. Magnetospheric observations show increases in particle flux and magnetic field simultaneously. With the keograms and ewograms, we find that the auroral drippings are different from other periodic structures in the motion and the temporal periodicity. To investigate the possible magnetospheric source of this structure, we simulate the entire process with the Rice Convection Model coupled with an MHD code (RCM-MHD). After long-lasting low-entropy plasma is supplied from the tailward boundary, frequent drippings and the accompanying oscillations in the near-Earth plasma sheet are reproduced. Our preliminary results suggest that the continuous plasma injection is considered to be possible magnetospheric source of the auroral dripping.
Investigating the importance of sub-grid particle formation in point source plumes over China using chemical transport model with a sub-grid parameterization
Authors: Wei Ying , Chen Xueshun
Published: February 2023

The influence of sub-grid particle formation (SGPF) in point source plumes on aerosol particles over eastern China was firstly illustrated by implementing a SGPF scheme into a global-regional nested chemical transport model with aerosol microphysics module. The key parameter in the scheme was optimized based on the observations in eastern China. With the parameterization of SGPF, the spatial heterogeneity and diurnal variation of particle formation processes in sub-grid scale were well resolved. The SGPF scheme can significantly improve the model performance in simulating aerosol components and new particle formation processes at typical sites influenced by point sources. The comparison with observations at Beijing, Wuhan, and Nanjing showed that the normal mean bias (NMB) of sulfate and ammonium could be reduced by 23%-27% and 12%-14%, respectively. When wind fields were well reproduced, the correlation of sulfate between simulation and observation can be increased by 0.13 in Nanjing. Considering the diurnal cycle of new particle formation, the SGPF scheme can greatly reduce the overestimation of particle number concentration in nucleation and Aitken mode at night caused by fixed-fraction parameterization of SGPF. In the regional scale, downwind areas of point source got an increase of sulfate concentration by 25%-50%. The results of this study indicate the significant effects of SGPF on aerosol particles over areas with the point source and necessity of reasonable representation of SGPF processes in chemical transport models.
Interplay between aboveground plant biodiversity, soil organic matter, and soil microbial functional diversity in a grazed Danish island ecosystem
Authors: O'Keeffe Joanne , Aagaard Kristensen Jeppe , Fløjgaard Camilla , Müller Carsten W.
Published: February 2023

Animal grazing is known to affect both, soil carbon storage and above and belowground biodiversity. However, we lack a more detailed understanding how specific soil properties might determine biodiversity and soil carbon storage as affected by grazing. Thus, in the present work we aim to connect the geo- and biodiversity with organic matter decomposition functionalities of the soil community, and thus identify how this regulates soil carbon and nitrogen storage. Therefore, we analysed aboveground plant biodiversity, soil microbial functional diversity, and soil organic matter (SOM) characteristics on a summer grazed island (Eskilsø) in a Danish fjord. Specifically, plant biodiversity analyses were conducted and topsoils sampled at thirty plots (4 replicated soil samples per plot) on the ca. 140 ha island. The plots cover the island’s main habitats: salt meadows, meadows, and developing dry grasslands. Soils were analysed for organic carbon (OC), total nitrogen (TN), organic phosphorus (OP), inorganic phosphorus (IP), and pH. Additionally, community level physiological profiles (CLPP) were analysed using the Microresp technique to make inferences about soil microbial functional diversity and activities. We are able to demonstrate that plant biodiverse plots contained greater contents and stocks of SOM. This also correlates with an increased soil microbial functional diversity. The findings are in line with the often observed positive interaction between aboveground diversity and belowground functionality of the soil biome in grassland ecosystems, partly due to increased amounts and diversity of rhizodeposits. As microbial activity is important for mediating the turnover of plant derived organic matter into more stable soil OM pools, this reflects the correlation with higher soil OC stocks and thus links to soil carbon persistence. For the studied island ecosystem we are able to demonstrate how the fate of soil organic matter is functionally linked to the interactions between above- and below-ground components of the ecosystem. 
WRF-PMCAMx: a mesoscale model for cloud-aerosol interaction studies
Authors: Sotiropoulou Georgia , Patoulias David , Pandis Spyros , Nenes Athanasios
Published: February 2023

Cloud-aerosol interactions constitute the largest source of uncertainty in predictions of the global climate. In this study we present WRF-PMCAMx, a powerful tool for detailed cloud-aerosol investigations. This consists of the Weather Research and Forecasting model (WRF; Skamarock et al., 2008) coupled with PMCAMx-UF (Patoulias et al. 2022). PMCAMx-UF is a three-dimensional chemical transport model with a high-resolution sectional bin aerosol approach. The aerosol fields predicted by PMCAMx-UF are used to update the cloud droplet and ice number predictions in the Morrison et al. (2005) microphysics scheme in the WRF atmospheric component. To evaluate the impact of this coupling, we compare the cloud, precipitation and radiation patterns predicted by WRF-PMCAMx over Europe to the diagnostic fields produced by the standard Morrison scheme in the open-source WRF code.REFERENCES:Morrison, H., Curry, J.A., and Khvorostyanov, V.I.: A New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part I: Description, Atmos. Sci., 62, 3683-3704 62, 2005 Patoulias, D. and Pandis, S. N.: Simulation of the effects of low-volatility organic compounds on aerosol number concentrations in Europe. Atmos, Chem Phys., 22, 1689-1706, 2022.Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D., Duda, M. G., … Powers, J. G.: A Description of the Advanced Research WRF Version 3 (No. NCAR/TN-475+STR). University Corporation for Atmospheric Research. doi:10.5065/D68S4MVH, 2008* This study is supported by the H2020-EU.1.3.- EXCELLENT SCIENCE - Marie-Skłodowska-Curie Actions project SIMPHAC (ID 8985685) 
Decadal intertidal vegetation development in an estuary and its effect on the wave damping capacity
Authors: Bootsma Jesse , Borsje Bas , van der Wal Daphne , Hulscher Suzanne
Published: February 2023

Intertidal vegetation is renowned for its capacity to reduce wave energy and thereby enhance coastal safety. At present, this concept is well established on local scales (meters to marsh-mudflat system) and relatively short terms (hours to years). However, the development of intertidal vegetation on larger scales (i.e. the spatial scale of an estuary and the temporal scale of decades) is unknown. Consequently, it is impossible at the moment to quantify the wave damping capacity at these scales. In this paper, the decadal spatiotemporal characteristics and dynamics of intertidal vegetation are studied by combining available data (e.g. from field surveys) and remote sensing techniques (Combining SAR and optical remote sensing). For this analysis, the Scheldt estuary, with a tidal reach of more than 160km from the mouth near Vlissingen, the Netherlands, till Gent, Belgium, is used as study area. Intertidal vegetation located in salt, brackish and freshwater environments is considered to cover the changes in salinity regimes in estuaries. More specifically, the vegetation species considered in this study are: Common glasswort (Salicornia europaea), Common cordgrass (Spartina anglica), Saltmarsh bulrush (Scirpus maritimus), Common reed (Phragmites australis) and Common willow (Salix alba). The variability in vegetation distribution in this study has three components: (1) the areal extent i.e. total marsh dimensions and associated variability in this (expansion/retreat); (2) the variability in vegetation characteristics e.g. density, biomass, height and seasonality; and (3) shifts in vegetation species i.e. going from one species to another at the same location over time. Since the wave damping capacity of a vegetated intertidal area is a combination of the wave attenuation from the bottom friction and the attenuation due to the presence of vegetation, the bed topography corresponding to the vegetation pattern is established from laser altimetry (LiDAR) data. Ultimately, the wave damping capacity of intertidal vegetated areas under various storm conditions is determined using a Simulating WAves Nearshore (SWAN) model, based on the spatial vegetation patterns and characteristics, as well as the variation in bathymetry. Quantification of the decadal dynamics of intertidal vegetation in estuaries and its impact on the wave damping capacity will help us to give recommendations for the effectiveness and the design of nature-based coastal protection measures.
Experimental study of turbulent kinetic energy of flow over scoured riverbed
Authors: Gilja Gordon , Drandić Luka , Fliszar Robert , Harasti Antonija
Published: February 2023

Rapid development of the instantaneous flow velocity instruments allows for high frequency measurement of turbulent flow field in the hydraulic flume. To obtain accurate and reliable flow measurement it is necessary to correctly configure the instrument using the manufacturer’s general guidelines. When instruments are used in highly turbulent flows, such as flows around bridge piers, selection of parameters is not straightforward and it generally requires validation against known data. In this study, experimental flow velocity data was collected in the hydraulic flume at three characteristic cross-sections – bridge profile, and upstream, and downstream profile. Velocity was measured on 10 points for each cross-section using Nortek Vectrino Profiler. Velocity measurements were processed to calculate turbulent kinetic energy at discrete points, after which TKE map was interpolated over the entire cross-section using QGIS. Results of TKE maps are compared for two characteristic flow rates and changes in TKE distribution respective to the flow downstream analyzed to quantify influence of the bridge pier and scour protection on the flow in the bridge vicinity. AcknowledgmentsThis work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046)