bluuebunny/crossref_metadata_2025 huggingface dataset:
Calving response to the propagation of a speedup pulse through the ice stream of Sermeq Kujalleq in Kangia (Jakoshavn Isbræ), Greenland
Authors: Wehrlé Adrien , Lüthi Martin P , Nap Ana , Kneib-Walter Andrea , Jouvet Guillaume , Rousseau Hugo , Walter Fabian
Published: February 2023

Sermeq Kujalleq in Kangia (Jakobshavn Isbræ), Greenland is one of the most studied glaciers in the world mainly due to its recent retreat associated with extremely fast ice stream flow and high solid ice discharge. However, large limitations remain in the understanding of its short-term ice dynamics as the study of sub-daily variations, generally undetectable in spaceborne observations, requires high-rate field measurements that are challenging to acquire. Here, we present glacier surface velocities determined in Post-Processed Kinematic (PPK) mode from eight autonomous Global Navigation Satellite System (GNSS) stations deployed in July 2022 along the ice stream at a distance of 4 to 30 kilometers from the calving front. During this field campaign, we identified an 8-hour-long glacier speedup which was recorded at all GNSS stations and reached up to 11% of the pre-event velocity, followed by a 12-hour-long slowdown of similar magnitude. We further found the peak velocity was first measured at a GNSS station 16 kilometers away from the calving front, then recorded consecutively at each of the three other downstream GNSS stations with a positive time lag corresponding to a ~3 km/h wave propagation speed. At the station closest to the calving front, the timing of peak velocity corresponded to the occurrence of large-scale calving events. We further present line-of-sight glacier surface velocities measured along three shear margin transects with a terrestrial radar interferometer deployed simultaneously with the GNSS array. Across all profiles, we observed a widespread and simultaneous response of fast- and slow-moving ice suggesting a strong coupling between the main trunk and the shear margins of the ice stream.
A New Strategy for Training Deep Learning Ensembles
Authors: Schanz Tobias , Greenberg David
Published: February 2023

Quantifying the error of predictions in earth system models is just as important as the quality of the predictions themselves. While machine learning methods become better by the day in emulating weather and climate forecasting systems, they are rarely used operationally. Two reasons for this are poor handling of extreme events and a lack of uncertainty quantification. The poor handling of extreme events can mainly be attributed to loss functions emphasizing accurate prediction of mean outcomes. Since extreme events are not frequent in climate and weather applications, capturing them accurately is not a natural consequence of minimizing such a loss. Uncertainty quantification for numerical weather prediction usually proceeds through creating an ensemble of predictions. The machine learning domain has adapted this to some extent, creating machine learning ensembles, with multiple architectures trained on the same data or the same architecture trained on altered datasets. Nevertheless, few approaches currently exist for tuning a deep learning ensemble. We introduce a new approach using a generative neural network, similar to those employed in adversarial learning, but we replace the discriminator with a new loss function. This gives us the control over the statistical properties the generator should learn and increases the stability of the training process immensely. By generating a prediction ensemble during training, we can tune ensemble properties such as variance or skewness in addition to the mean. Early results of this approach will be demonstrated using simple 1D experiments, showing the advantage over classically trained neural networks. Especially the task of predicting extremes and the added value of ensemble predictions will be highlighted. Additionally, predictions of a Lorenz-96 system are demonstrated to show the skill in forecasting chaotic systems.
A data-driven framework for estimating GIA from GPS and GRACE data
Authors: Vishwakarma Bramha Dutt , Ziegler Yann , Royston Sam , Bamber Jonathan L.
Published: February 2023

GIA from forward models suffer from large uncertainties due to approximations and assumptions on the Earth rheology and ice load history. These uncertainties propagate to uncertainties in ice-sheet mass balance and sea level budget studies. Therefore, GIA estimates from contemporary geodetic datasets are gaining interest. The challenges of obtaining data-driven GIA include solving a geophysical inversion that does not have a unique solution and often requires a-prior information and several approximations. In this work, a novel geophysical framework is developed that uses GPS and GRACE data to estimate GIA signal. The method relies on geophysical relations between geopotential and vertical land movement (VLM) caused by GIA and present-day mass changes. For example, the elastic response of solid Earth to the positive surface mass load results in a negative VLM, while a positive GIA mass leads to a positive VLM. We use these relations to express GPS observed VLM and GRACE observed gravity field anomalies in terms of GIA and present day mass change. The method is first shown to work in a closed-loop synthetic experiment and then applied to the NGL provided GPS velocities and GRACE spherical harmonic coefficients provided by ITG Graz. Our GIA estimates differ significantly from commonly used GIA models (such as ICE-6G) over Alaska and central Greenland. Our GIA rates over Alaska are around 5 mm/yr, which matches with several regional studies over Alaska. Similarly, there is a lot of ambiguity over Greenland ice-load history and our results may provide informative input to the ongoing debate. Our estimates are data-driven and are therefore able to pick them up. We also discuss the uncertainties, caveats and limitations of our method and its implications. The published GIA product is made openly available at one degree grid resolution. 
Description of the Gulf of Cadiz surface circulation from drifters
Authors: Bolado-Penagos Marina , de Oliveira Júnior Luciano , Vázquez Águeda , Relvas Paulo , Garel Erwan , Bruno Miguel
Published: February 2023

The Gulf of Cadiz is located between the North Atlantic Ocean and the Mediterranean Sea. The majority of studies have focused on the presence of the Mediterranean Outflow water (so-called, MOW) in depth. Nevertheless, there are not so many studies that analyse the surface circulation in this area.To improve the knowledge of the former circulation, an experiment was conducted with Lagrangian drifters during the autumn of 2022 off the western sector of the northern margin of the Gulf of Cadiz. A total of 8 drifters (SouthTEK®, tethered to a 0.5 m drogue) were deployed in two different areas: (1) 4-offshore drifters (GPS tracking and Iridium coverage) over the shelf slope (200 m isobath) off Cape San Vicente (24 September, 36.837ºN 8.893ºW) sending position every 2 hours; and (2) 4-coastal drifters sending GPS positions every hour, launched in pairs on the inner shelf eastward of Cape Santa Maria (12 October): two at 25 m water depth (37.080ºN 7.476ºW) and two at 100 m water depth (36.993ºN 7.423ºW). The resulting position time-series was between 8 and 18 days for the coastal drifters and ~1-3 months for the offshore ones.The 4 offshore drifters were displaced together eastward for more than one month after their deployment. They completed an anticyclonic gyre centered around ~36.500ºN 7.500ºW, in agreement with the geostrophic field for these days. All drifters reach the Strait of Gibraltar, but not at the same time (and only two of them entered the Alboran Sea). One drifter was able to enter the Strait when it arrived at the easternmost Gulf of Cadiz (1-month after the deployment). The other drifters reached the Strait later (1.5 and 2.5-months after the deployment) and were conditioned by the Easterly wind blowing over the Strait at that time, describing different trajectories before entering the Strait that are typical of e.g., Coastal Counter Current and sub-mesoscale structures along the Moroccan coast. All the coastal drifters described a similar cyclonic gyre extending up to Cape Santa Maria (~7 to 8ºW). This structure is in agreement with the presence (previously studied by other authors) of a Coastal Counter Current. Moreover, a drop in the Sea Level Anomaly and a signature of cold temperature (Sea Surface Temperature) are observed in this area by the days of the study.Drifter trajectories have revealed new insights into the surface circulation of the Gulf of Cadiz (i.e. meso- and sub-mesoscale processes). These trajectories have shown the connection between the surface water of the westernmost Gulf of Cadiz with the Alboran Sea. Moreover, these results could help to understand the transport patterns of floating litter or larvae (among others) in the area.
Displacement of Cerro Azul and Sierra Negra volcanoes, Galápagos Archipelago, during 2007–2009 and 2018–2021 measured from SBAS InSAR
Authors: Kim Seohyeon , Kim Taewook , Han Hyangsun
Published: February 2023

Cerro Azul and Sierra Negra are two of the most active volcanoes in the Galápagos Archipelago, the eastern Pacific Ocean, with recent eruptions occurring in May-June 2008 and June-August 2018, respectively. In this study, surface displacements on the summit caldera of Cerro Azul and Sierra Negra volcanoes were investigated by applying the Small BAseline Subset (SBAS) technique to 13 ALOS-1 PALSAR images acquired from March 2007 to October 2009 and 94 Sentinel-1 SAR images acquired from April 2018 to April 2021. A subsidence of ~28 cm was observed outside the northern caldera rim of Cerro Azul from March to September 2008. Except for this period, the surface displacement of Cerro Azul was rarely observed from the ALOS-1 observations. Uplift on the summit caldera of Sierra Negra was observed during 2007–2009 and its velocity was varied by the eruptive phases of Cerro Azul. During the year preceding the eruption of Cerro Azul (March 2007 to March 2008), the summit caldera of Sierra Negra was uplifted at a velocity of 0.37 m/yr. However, the uplift velocity slowed to 0.14 m/yr between March 2008 and September 2008, when Cerro Azul erupted. For one year after the Cerro Azul eruption (September 2008 to October 2009), the uplift velocity of the Sierra Negra summit increased to 0.29 m/yr. The summit caldera of Sierra Negra was uplifted ~260 cm from April 2018 to April 2021, except for its eruptive phase when the surface displacement could not be observed from the SBAS result due to low interferometric coherence. The northern caldera rim of Cerro Azul subsided ~3 cm during the 2018 eruptions of Sierra Negra, then was uplifted by ~13 cm over the next 3 years. 
Seasonal evaluation of morphological indexes in quantifying snow cover patterns in the Zugspitze area
Authors: Ferrarin Lucia , Koch Franziska , Schulz Karsten , Bocchiola Daniele
Published: February 2023

The spatiotemporal distribution of snow cover affects several processes at different scales, such as the Earth’s energy balance, the hydrological cycle and ecosystems functions, with important implications on many aspects of human life. Topography, meteorological conditions in general and wind in particular affect the evolution of seasonal snow cover patterns during snow accumulation and ablation. With the help of remote sensing techniques, such as Sentinel-2 imagery, it is feasible to study snow cover patterns also in complex terrain. Satellite based morphological analysis of snow cover patterns may provide i) information on snow cover and its connection to morphology and alpine topography ii) a valuable complement to ground-based data and snow-hydrological simulations. In this study, we evaluate the effectiveness of two types of geometric indexes, i) MN, Minkowsky numbers (representing area, perimeter and Euler characteristic), and ii) CL, Average chord length, in quantitatively describing the morphology of Sentinel-2 derived snow cover patterns within the high-alpine area of Zugspitze at the boarder of Germany and Austria for a five-year period. MN and CL have been used previously in different fields, e.g. soil sciences, but to the authors’ knowledge, these measures have never been applied in the field of snow cover pattern monitoring before. We present the seasonal evolution of MN and CL, as well as their correlation to topographic features (e.g., aspect, slope, curvature) and meteorological and snow variables. The individual indexes show distinct differences during snow accumulation and ablation and a clear annual periodicity. MN and CL can effectively quantify some aspects of the dynamic of snow cover patterns, although further analysis are necessary to conclude if such morphologic pattern descriptors can substantively improve the accuracy of the understanding and the modelling of snow-related processes.
Evaluation of Amd production under experimental conditions
Authors: Martinez-Sanchez Maria Jose , Garcia Lorenzo Mariluz , Martínez Lopez Salvadora , Martinez Martinez Lucia Belen , Hernandez Cordoba Manuel , Banegas Garcia Ascension , Bech Jaime , Hernandez Perez Carmen , el Jamaoui Imad , Perez Sirvent Carmen
Published: February 2023

In order to predict the future behaviour of technosols designed for the remediation of sites contaminated with mining waste, a pilot experiment was carried out in containers under an enclosed building.One-metre cubic polyvinyl chloride (PVC) containers were used and filled with soil of the different types that are abundant on the site. Four soil types were selected with different textures (sandy to silty-clay), different mineralogy and different PTE content. Soil mixtures were also prepared with limestone filler at different proportions (30, 40 and 50 %).These containers were subjected to a humidity and drying process, simulating the rainfall conditions that the site receives as an average annual value, in 10 successive cycles, maintaining the experience for 4 years. The drains obtained were analysed and their corresponding crystallised phases were obtained and characterised by XRD and electron microscopy. The metals determined were Fe, Cd, Cu, Pb, As and Zn.This experiment allows us to differentiate the behaviour of the selected soils with respect to humidity, since the untreated soils with a clayey loam texture are AMD producers, with very low pH and a high mobilisation of metals. In contrast, sandy textured soils and soils containing 30 % or more limestone filler have a pH close to 7 and small metal contents close to the limit of quantification.Efflorescences are more abundant in those leachates rich in Zn and Fe, being copiapite, hexahydrite, bianchite and gypsum the main soluble phases associated with these leachates.  Finally, the percolates with a higher salt load correspond to the third percolation carried out approximately nine months after the start of the experiment. 
Microservice architecture to enable fast assessment of the NatCat events based on EO and geospatial data
Authors: Sarna Karolina , Hiekkasaari Johannes , Taajamo Joni
Published: February 2023

Fast response to natural catastrophe events is crucial in our fast changing world. Creating comprehensible solutions based on the Earth Observation (EO) and geospatial data is complex and requires combining multiple data sources and maintaining high level of configuration parameters.
In this talk we discuss the application of microservices architecture to tackle some of the issues inherent to building products based on EO and geospatial data. We will present how decomposing sophisticated algorithms into small services can help with continuous delivery, scaling and deployment of large, complex applications that can be reused for various products. This architecture enables reproducibility of analysis which is a crucial component for applying machine learning and automation into any EO based product. We will also address the additional complexity of creating a distributed system as well as high dependency on data consistency and availability.
Deterministic and Stochastic Chaos characterise Laboratory Earthquakes
Authors: Gualandi Adriano , Faranda Davide , Marone Chris , Cocco Massimo , Mengaldo Gianmarco
Published: February 2023

We analyze frictional motion for a laboratory fault as it passes through the stability transition from stable sliding to unstable motion. We study frictional stick-slip events, which are the lab equivalent of earthquakes, via dynamical system tools in order to retrieve information on the underlying dynamics and to assess whether there are dynamical changes associated with the transition from stable to unstable motion. We find that the lab seismic cycles exhibit characteristics of a low-dimensional system with average dimension similar to that of natural slow earthquakes (<5). We also investigate local properties of the attractor and find maximum instantaneous dimension >10, indicating that some regions of the phase space require a high number of degrees of freedom (dofs). Our analysis does not preclude deterministic chaos, but the lab seismic cycle is best explained by a random attractor based on rate- and state-dependent friction whose dynamics is stochastically perturbed. We find that minimal variations of 0.05% of the shear and normal stresses applied to the experimental fault influence the large-scale dynamics and the recurrence time of labquakes. While complicated motion including period doubling is observed near the stability transition, even in the fully unstable regime we do not observe truly periodic behavior. Friction's nonlinear nature amplifies small scale perturbations, reducing the predictability of the otherwise periodic macroscopic dynamics. As applied to tectonic faults, our results imply that even small stress field fluctuations (less or about 150 kPa) can induce coefficient of variations in earthquake repeat time of a few percent. Moreover, these perturbations can drive an otherwise fast-slipping fault, close to the critical stability condition, into a mixed behavior involving slow and fast ruptures.
Understanding the triggering mechanisms of reservoir-triggered seismicity at Nova Ponte, Brazil, through hydro-mechanical modeling
Authors: Vilarrasa Victor , Raza Haris , Kivi Iman Rahimzadeh , França George Sand
Published: February 2023

Reservoir impoundment is usually accompanied by induced/triggered seismicity. The rise in the number of planned hydropower plants requires improving the understanding of the causes of this induced/triggered seismicity, which eventually could serve to propose mitigation measures to reduce the induced/triggered-seismicity risk. We investigate the case of reservoir-triggered seismicity at Nova Ponte, Brazil, where triggered seismicity started shortly after reservoir impoundment, with the maximum magnitude of M3.5 when reaching the highest water level on the dam, and followed by delayed seismicity, with the largest earthquake being a M4.0 about 4.5 years after impoundment. We have built a hydro-mechanical fully-coupled numerical model reproducing the T shape of the reservoir and including the three geological layers placed below the reservoir down to 10 km depth. Simulation results serve to identify the nodal plane, from the two nodal planes of the proposed focal mechanism, which nucleated the seismicity of the M3.5 earthquake: a vertical, E-W-oriented strike-slip fault with a reverse-displacement component. The initial seismicity was triggered by the undrained response of the subsurface to the loading of the reservoir. We also find that the delayed seismicity was triggered by pore pressure diffusion, bringing a critically oriented vertical fault to failure conditions. The vertical permeability to allow the pore pressure perturbation to reach the depth of the M4.0 earthquake, i.e., 3 km depth, in 4.5 years is 6.6·10-15 m2, two to three orders of magnitude higher than the expected permeability of the host rock, a low-permeability mica-schist. We contend that hydro-mechanical models are a useful tool to understand the triggering mechanisms of reservoir-triggered seismicity.
Bottom trawling impacts on benthic-pelagic coupling in the North Sea
Authors: Tiwari Pooja , Porz Lucas , Daewel Ute , Schrum Corinna
Published: February 2023

Bottom trawling has a direct impact on biogeochemical cycling and benthic-pelagic coupling. Despite extensive trawling activities in many shelf seas, the effects on benthic-pelagic exchanges is often not considered in marine ecosystem simulations. In this study, in order to gauge the effects of bottom trawling on North Sea ecosystem productivity, two model simulations were carried out for the period 2000-2005 using the 3D, fully coupled ecosystem model SCHISM-ECOSMO, which allows for coupled simulation of the benthic and pelagic ecosystem. The first simulation includes only natural resuspension while the second experiment also considers a parametrization for bottom trawling induced resuspension. Daily forcing for bottom trawling resuspension rates was generated based on available data of fishing activity including the position, size and engine power of individual vessels, in combination with estimated resuspension rates of various fishing gears in different types of sediment. The results of these simulations were then analyzed with regard to the importance of bottom trawling for the pelagic primary production of the North Sea ecosystem. In addition, we analyzed trawling-induced changes in bottom water oxygen and sedimentary carbon, phosphorus and nitrogen pools.
Microstructural analysis of zoisite from a naturally deformed eclogite (Syros, Greece): Implications on the rheology of metabasic rocks along the subduction zone interface
Authors: Morales Luiz F. G. , Tokle Leif , Salvadori Leonardo
Published: February 2023

Subducted metabasic rocks play an important role in defining the rheology of the subduction zone interface and are believed to be the primary source of volatiles for arc magmatism and fluid-induced seismicity. The rheology of metabasic rocks along the subduction zone interface are typically modeled based on the strength of omphacite, however metabasic rocks are made up of a variety of different minerals. In this study we present a detailed microstructural analysis of zoisite from an eclogite collected on Kini beach in Syros, Greece and make the argument that zoisite may be important in defining the rheology of metabasic rocks along the subduction zone interface.The studied sample is a prograde blueschist to eclogite facies rock primarily containing glaucophane, omphacite, zoisite, and garnet with minor amounts of chlorite retrogression at the rims of large omphacite grains. A hand sample (~12 cm in diameter) was polished and several thin sections were made for analyses. The hand sample shows strain is primarily localized into zoisite-rich layers suggesting zoisite was the weakest mineral when the sample was deforming. Backscatter electron images of the zoisite layers show a homogeneous mixture of zoisite and clinozoisite, where clinozoisite makes up ~10% of the zoisite layers. Zoisite grains are on average twice as large as clinozoisite with an average grain size of 61 μm, whereas clinozoisite has an average grain size of 36 μm. Both phases have strong shape and crystallographic preferred orientations. Both phases show poles to (100) maxima roughly orthogonal to the reference foliation, while poles to (010) develop a girdle sub-parallel to the foliation plane, and poles to (001) are uniformly distributed. EBSD analysis shows that a few zoisite and clinozoisite grains develop subgrain boundaries, suggesting dislocation related mechanisms played a minor role. Based on our analysis, zoisite is interpreted to have deformed primarily by a combination of rigid body rotation and dissolution-precipitation, which lead to the precipitation of clinozoisite. Further analyses will be conducted on zoisite as well as other common minerals within the sample.
Generating ocean initial condition for coupled forecasts through nudged NEMO experiments
Authors: Pelletier Charles , Roberts Christopher D. , Vitart Frederic , Balmaseda Magdalena A. , Mogensen Kristian , Sandu Irina
Published: February 2023

Accurate ocean initial conditions are beneficial to coupled ocean - atmosphere forecasts in several ways depending on context. On short time scale (days), some extreme, societally high-impacting meteorological events such as tropical cyclones are associated with exceptionally intense air-sea exchanges, thus requiring good knowledge of the initial state of the upper ocean layers. As the forecast evaluation time scale gets longer (seasonal, decadal), the information contained within the atmospheric initial conditions becomes virtually ineffective to the advantage of that contained within the ocean’s.In phase one of the Destination Earth (DestinE) initiative of the European Union, ECMWF is responsible for delivering the first two digital twins, on weather extremes and climate change adaptation. These will rely on the fusion of observations and cutting-edge, high-resolution versions of Earth system models. Developing a cheap, affordable method for generating realistic high-resolution ocean initial conditions is particularly critical to both these forthcoming digital twins developed in DestinE. In this presentation, we thus introduce a new ocean initial condition generation method built to meet these specific needs.This method consists in running preliminary nudged ocean-standalone experiments, using the NEMO ocean model, which is part of the ECMWF’s Integrated Forecasting System. Its main technical novelty is the adaptation of a former sea-ice nudging scheme to NEMO’s multicategory SI3 sea-ice model, and it can be significantly cheaper than relying on ocean data assimilation, particularly at high resolutions. However, this method touches on several matters related to the ability of ocean models to be diverted from their natural equilibrium by being constrained towards increasingly realistic states. We investigate the criteria for obtaining realistic ocean initial condition using distinct combinations of model and nudging dataset resolutions, and evaluate the resulting skill of coupled ocean - atmosphere forecasts.
Beyond traditional summer air temperature signals in subarctic tree rings using hydrogen and oxygen isotopes
Authors: Fonti Marina , Saurer Matthias , Porter Trevor , Zharkov Mikhail , Barinov Valentin , Taynik Anna , Kirdyanov Alexander , Knorre Anastasya , Wegmann Martin , Trushkina Tatyana , Koshurnikova Nataly , Vaganov Eugene , Myglan Vladimir , Siegwolf Rolf , Churakova (Sidorova) Olga
Published: February 2023

Classical tree-ring parameters like tree-ring width, maximum latewood density and cell wall thickness record summer air temperature at high latitudes well and allow for the reconstruction of summer temperature over centuries and millennia. However, information about other climatic factors (e.g. moisture and sunshine duration) is limited in these proxies, especially for temperature-limited environments in subarctic forests growing on permafrost soils. The application of stable hydrogen and oxygen isotopes can provide complementary information about moisture changes and solar irradiation.Solar irradiation and its seasonal distribution play an important role for trees in terms of photosynthesis and carbohydrate production, which can influence deuterium variations in organic matter in addition to hydrological processes. We found that hydrogen and oxygen isotopes in larch tree-ring cellulose from Siberia show a strong link with summer sunshine duration during the growth season. Negative correlations with sunshine duration during autumn of the previous year and winter of the current year can be related to the lack of light during polar nights at subarctic sites (> 60º N) and lack of needles in larch trees to produce photosynthates in a cold environment. Indirect effects might also arise as a high amount of winter sunshine means persistent high-pressure systems with low precipitation, therefore negatively affecting snow accumulation, which is an important water source after snow melt.Uptake of winter precipitation is possible in the warming spring and summer months after snowmelt and thawing of the active soil layer, resulting in significant correlations between tree-ring oxygen values and winter-spring air temperatures. Oxygen isotopes in organic matter are influenced by variations in the isotopic composition of source water, which is closely related to that of precipitation and soil water (though modified by evaporation at the soil surface).Furthermore, we observed that summer vapor pressure deficit is positively and significantly recorded in stable oxygen isotopes from northeastern Siberia, while continuously represented through spring-summer months in western Canada. Hydrogen tree-ring isotopes from the Canadian subarctic recorded a negative significant correlation with summer relative humidity, opposite to northeastern Siberia.The application of dual hydrogen and oxygen stable isotopes in tree rings can expand our knowledge beyond traditional summer air temperature reconstructions and will help to improve climate reconstructions over the past millennia.Acknowledgements: This work was supported by the project RSF 21-17-00006.
Dense spatial variation of the eukaryotic and prokaryotic communities on the Gulkana Glacier, Alaska
Authors: Uetake Jun , Ono Masato , Usuba Suzunosuke , Tsushima Akane , Takeuchi Nozomu
Published: February 2023

Glacier retreat due to the warming climate is remarkable all over the world. In addition to climate warming, the “biological albedo reduction”, which the pigmented algae reduce the albedo of the glacier, enhances ice melting. Therefore, the spatial distribution of those algae is important for the glacier's mass balance. Although the altitude result in the air temperature and the duration of snow cover is recognized as the factor to affect the spatial distribution, the distribution pattern is more heterogeneous in the same altitude area. To understand the heterogeneity of snow algae and associating microbes and their effects on the glacier albedo, both eukaryotic and prokaryotic communities were analyzed using an amplicon sequencing approach in the dense coverage of the ablation area of a single glacier (total 54 sites over Gulkana Glacier, AK, USA). Furthermore, microbial diversities were analyzed with environmental factors such as carbon contents and nutrients. As a result, we found the green algae amplicon sequence variants (ASVs) closely related to the pigmented algae, Sanguina nivaloides, and Chlainomonas sp. from the surface ice and cryoconite and will show the spatial variation of microbial community structures and diversities and the relationship between the environmental factors.
Effect of antecedent rainfall on daily flow forecasting using a soil moisture accounting algorithm
Authors: Eslami Zahra , Abdollahi Khodayar , Kirchner James W
Published: February 2023

Studies have shown both rainfall and soil moisture have a noticeable impact on daily runoff generation. In many cases, measured soil moisture data are unavailable, and soil moisture is instead estimated by various proxies, including the sum of precipitation over a number of days. Here we test the predictive value of antecedent rainfall for daily flow forecasting, using the Kuhesookhteh Watershed in Iran as a test case. A 20-year runoff time series was simulated using the Soil Moisture Accounting Algorithm of HEC-HMS. The results showed a Nash-Sutcliffe Efficiency of 0.67 for the calibration period (2000-2015) and 0.53 for the validation period (2015-2020).Comparisons of daily simulated and observed flows show that the soil moisture accounting algorithm did not forecast the high values of streamflow well. We found a non-linear relationship between antecedent precipitation and the residuals of the flow simulation. Flow simulations substantially improved (i.e., residuals substantially decreased) when up to 4-5 days of antecedent rainfall were used as soil moisture proxies; further extending this antecedent rainfall interval to 7 days resulted in only minor further improvement. Since antecedent rainfall can be considered as a proxy for soil moisture, we infer that soil moisture acts as a system memory that retains information for at least 4-5 days. This inference is also supported by a data-driven, model-independent technique (Ensemble Rainfall-Runoff Analysis), applied to quantify the nonstationary runoff response of the Kuhesookhteh Watershed under different levels of antecedent rainfallKeywords: soil water balance, surface abstraction, effective rainfall, water budget 
The record-shattering 2021 Pacific Northwest heatwave – challenges and opportunities for attribution and event storylines
Authors: Fischer Erich
Published: February 2023

Parts of western North America experienced a heatwave in late June 2021that many would have conceived impossible based on observations so far. In Lytton, Canada, temperatures peaked at 49.6°C, and the area-average daily maximum temperature record across the Pacific Northwest was broken by nearly 5°C. Given the exceptional intensity of the eventsome media outlets and scientists raised the questions whether heat extremes intensify faster than previously projected based on climate models, or whether current generations of climate models miss crucial processes and are thus unable to even reproduce such an event.. Here I address these questions and highlight some of the challenges for widely methods in model evaluation and attribution.First, I review some of the recent literature detailing the key physical mechanisms driving the Pacific Northwest heatwave. I address some of the key scientific challenges regarding the quantification of return periods, event attribution, model evaluation and near-term projections. Widely used methods estimating stationary return periods based on the observational record up to the year before imply that such an event had an infinite return period, i.e., that it would never happen. Even when taking into account the non-stationarity of a warming climate, the exceedance probability would be zeroor nearly zero depending on the estimation of the confidence intervals, the duration of the event and whether the event itself is included in the fit. I discuss some potential ways forward in addressing the above challenges and in quantifying the potential intensity of record-shattering events in the near future.  
Volunteer Observing Ships in transitional oceanic regions: the Northeast African upwelling and the Strait of Gibraltar
Authors: Gonzalez-Davila Melchor , Curbelo-Hernández David , Santana-Casiano J. Magdalena , González-González Aridane , González-Santana David
Published: February 2023

The spatio-temporal variability of the surface ocean CO2 system and the air-sea CO2 fluxes were studied in the Northeast Atlantic and the Strait of Gibraltar, including the northwest African coastal transitional region and the easternmost archipelagic waters of the Canary Islands. The surface underway high-frequency data was collected by a surface ocean observation platform (SOOP) aboard a volunteer observing ship (VOS). The variability of the CO2 fugacity in seawater (fCO2,sw) was strongly driven by the seasonal pattern of the sea surface temperature (SST), which increased with latitude and was lower throughout the year in the high-intense African coastal upwelling. In the Strait of Gibraltar, the changes in the depth of the Atlantic-Mediterranean Interface layer and the tidal and wind-induced upwelling influenced the surface CO2 distribution. The variability of the CO2 fugacity (fCO2,sw) in this high-variable semi-enclosed area was mainly driven by temperature despite the significant influence of non-thermal processes in the southernmost part. The fCO2,sw increased from winter to summer by 11.84 ± 0.28 µatm ºC-1 in the Canary archipelago and by 11.71 ± 0.25 µatm ºC-1 along the northwest African continental shelf. In the Strait of Gibraltar, the gradient was lower and showed differences between the northern and southern sections (9.02 ± 1.99 and 4.51 ± 1.66 µatm ºC-1, respectively). The annual cycle (referenced to 2019) of total inorganic carbon normalized to a constant salinity of 36.7 (NCT) indicated that the net community production in the Northeast Atlantic represented >90% of the reduction of inorganic carbon while air-sea CO2 exchange described <6%. The net community production processes in the Strait of Gibraltar described 93.5-95.6% of the total NCT change, while the contribution of air-sea exchange and horizontal and vertical advection was found to be minimal (<4.6%). According to the seasonality of air-sea CO2 fluxes, the entire region behaved as a strong CO2 sink during the cold months and as a weak CO2 source during the warm months. A net annual CO2 sink behaviour was observed in the Canary basin (-0.26 mol C m-2 yr-1), in the northwest African coastal transitional area (-0.48 mol C m-2 yr-1) and in both the northern and southern section of the Strait of Gibraltar (-0.82 and -1.01 mol C m-2 yr-1). The calculated average air-sea CO2 flux for the area of study in Northeast Atlantic and in the Strait of Gibraltar was, -2.65 ± 0.44 TgCO2 yr-1 (-0.72 ± 0.12 TgC yr-1) and -7.12 Gg CO2 yr-1 (-1.94 Gg C yr-1), respectively.
Simulating deformation structure in viscous-plastic sea-ice models with CD-grid approaches
Authors: Mehlmann Carolin , Capodaglio Giacomo , Danilov Sergey
Published: February 2023

Linear Kinematic Features (LKFs) are found everywhere in the Arctic sea-ice cover. They are strongly localized deformations often associated with the formation of leads and pressure ridges. Viscous-plastic sea-ice models start to produce LKFs at high spatial grid resolution, typically with a grid spacing below 5km.  Besides grid spacing, other aspects of a numerical implementation, such as discretization details, may affect the number and definition of simulated LKFs. To explore these effects, simulations with different sea-ice models such as MPAS, CICE, ICON, FESOM and MITgcm are compared in an idealized configuration.We found that the nonconforming finite-element  CD-grid discretization produces more LKFs than the CD-grid approximation based on a sub-grid discretization. Furthermore the nonconforming finite-element approach simulates the same number of LKFs as conventional Arakawa A-grid, B-grid, and C- grid methods, but on grids with less degrees of freedom ( a  coarser mesh). This is due to the fact that CD-grid approaches have a higher number of degrees of freedom to discretize the velocity field. Due to its enhanced resolving properties, CD-grid methods are an attractive alternative to conventional discretizations. 
Evaluation of CMIP6 GCMs: the perspective of RCM boundary conditions
Authors: Holtanova Eva , Belda Michal , Halenka Tomas
Published: February 2023

Global climate models (GCMs) represent invaluable instrument for various purposes, most prominently studying climate system dynamics, evolution of past climates and climate change projections. The newest set of GCM simulations has been produced under CMIP6 initiative coordinated by the the World Climate Research Programme’s (WCRP) Working Group on Coupled Modelling. Due to their coarse spatial resolution, some kind of downscaling is necessary for applications of GCM outputs on regional and local scales, with dynamical downscaling using regional climate models (RCMs) being a common solution of this issue. Clearly, the outputs of RCMs are influenced by the boundary conditions provided at the lateral boundaries of the integration domain. The magnitude of this influence is subject of ongoing research and depends on various aspects including the geographical region, temporal scale, climatic variable etc. Nevertheless, previous studies proved that an analysis of boundary conditions is needed for for proper RCM evaluation. Especially with regard to potential error propagation.              In present study we evaluate the simulation of CNRM-ESM2-1, one of the CMIP6 GCMs, and compare it to other CMIP6 ensemble members. The CNRM-ESM2-1 is being used as driving model for convective-permitting simulation of Aladin-CLIMATE RCM within Czech national project PERUN aimed at creation of updated climate change scenarios for the Czech Republic. We concentrate on historical GCM simulations in the period of 1990-2014, and use reanalysis ERA5 as the reference. The analysis is conducted over the boundaries of Aladin-CLIMATE/CZ intergration domain, which covers Central Europe. The deviations of the driving GCM (CNRM-ESM2-1) from reanalysis are compared to other CMIP6 GCMs. We also evaluate uncertainty arising from natural climate variability using perturbed initial conditions ensemble of CNRM-ESM2-1.
Ice nucleating particle measurement at Helsinki
Authors: Perez Fogwill Germán , Welti André , Servomaa Henri , Timo Anttila , Piedehierro Ana , Leskinen Ari , Komppula Mika , Hyvärinen Antti , Asmi Eija
Published: February 2023

Ice nucleating particles (INPs) are particles in the atmosphere that are able to initiate the freezing of water droplets, a process known as ice nucleation. INPs are important to study because they play a crucial role in many atmospheric processes, including the formation of clouds, precipitation, and the radiative properties of clouds. For example, INPs can influence the concentration, size, and shape of ice crystals in clouds, which can in turn affect the reflectivity and lifetime of the clouds. This can have significant impacts on Earth's radiative balance and climate. The most relevant process of ice crystal formation in mixed-phase clouds (MPC) is by immersion freezing (Ansmann et al., 2009). Immersion freezing takes place when an INP is immersed in a water droplet and freezing is triggered on the particle's surface. In this research, we present a series of INP concentration measurements obtained using a novel assay under development at the Finnish Meteorological Institute in Helsinki. The focus of our research is to evaluate the consistency and replicability of these measurements.  To determine the contribution of different aerosols to the INP spectrum at different temperatures, we collect atmospheric particles onto membrane filters and analyze the concentration of INPs in a laboratory freezing experiment. In this experiment, we produce an aqueous solution with collected atmospheric particles and monitor identical aliquots of the aqueous solution while they are cooled until freezing. Finally, using the frozen fraction of aliquots at a given temperature, the volume of each aliquot, and the sample's air volume, the cumulative number of INPs in the given sample at each temperature is calculated following (Vali, 2019). Three automatic samplers were run in parallel to collect particles onto the membrane filters using different sampling schemes. For example, collecting daily samples with three different sampling flows. With these measurements, we will analyze the influence of the sampled air volume, air flow, and sampling duration on the INP concentration measurements. ReferencesAnsmann, A. et al. (2009) Evolution of the ice phase in tropical altocumulus: SAMUM lidar observations over Cape Verde Atmosphere, 9(9), 357Vali, G., (2019). Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: Methods of calculation, applications, and confidence limits. Atmos. Meas. Tech., 12(2), 1219-1231. https://doi.org/10.5194/amt-12-1219-2019
Long-term soil warming changes the quantity but not the composition of primary metabolites of tree fine roots
Authors: Liu Xiaofei , Heinzle Jakob , Tian Ye , Salas Erika , Kwatcho-Kengdo Steve , Borken Werner , Schindlbacher Andreas , Wanek Wolfgang
Published: February 2023

Abstract: Climate warming poses major threats to temperate forests, but the response of plant root metabolism has remained unclear. Understanding and predicting the impact of climate warming on the root metabolome represents a grand challenge and a major opportunity to predict the belowground functioning of forests in a warmer climate. We here studied the impact of long-term soil warming (>14 years, ambient versus +4 °C) on the fine root metabolome across three seasons (spring, summer, and autumn) for two years in a spruce-dominated mountain forest in the Austrian Limestone Alps. Root primary metabolites were analyzed with a liquid chromatography-mass spectrometry metabolomics platform (LC-Orbitrap MS). A total of 44 primary metabolites were identified in roots (19 amino acids, 12 organic acids, and 13 sugars). Warming and season had significant effects on total primary metabolite concentration, but no interaction effect. Warming increased the amino acid and sugar concentrations but did not affect organic acids. This may be explained by increased activity of the protein amino acid (such as arginine, glycine, and lysine) biosynthesis and metabolism and/or of root carbohydrate metabolism and transport under warming. The non-metric multidimensional scaling (NMDS) showed that soil warming was not significantly affecting the primary metabolite profiles, but year and season had significant effects. Season impacted primary metabolite profiles through changing soil temperature and years by effects on the soil environment (soil temperature and soil moisture) and root morphology (root length, specific root area, specific root length, and root diameter). In addition, we found that the root metabolism activity in warmed plots was lower than in control plots at the same soil temperature. Our data indicated that root metabolism in long-term warmed soil undergoes thermal acclimation, which may help match root metabolism with the required nutrient uptake and assimilation.Keywords: Soil warming, root metabolism, primary metabolites, temperate forest.
Assessing the role of thermodynamic drivers underlying extreme heat in a warming climate
Authors: Schumacher Dominik L. , Hauser Mathias , Seneviratne Sonia I.
Published: February 2023

In recent years, heatwaves around the globe have eclipsed long–term maximum temperature records. While a stronger warming over land than sea is both expected and observed, regional hot extremes are warming at an even faster pace. Modeling studies have suggested that soil moisture–temperature feedbacks drive this amplification in climate projections of the ongoing century, and there is solid observational evidence of a link between high temperatures and desiccating soils for individual events: dry soils invoke a shift in the surface energy partitioning toward sensible heating, thereby promoting higher air temperatures. A particularly notable heatwave unfolded in late June 2021 in the Pacific Northwest, baffling the scientific community with its high intensity. Using a combination of reanalysis data and factorial Earth System Model simulations, we show that heat released from condensation over the North Pacific and local soil moisture deficits strongly contributed to the extreme heat where the temperatures were most anomalous. Mediated by desiccating soils, our analysis also points to complex land–atmosphere interactions beyond intensified surface sensible heating. Since it remains unclear to what extent an enhanced thermodynamic potential — such as epitomized by this remarkable “black swan event” — is responsible for the observed exacerbation of heatwaves in recent decades, we we also investigate the link between summertime soil drought and hot extremes in our changing climate.