bluuebunny/crossref_metadata_2025 huggingface dataset:
The EGU Geoscience Education Field Officer Programme is growing!
Authors: P. Correia Gina , Realdon Giulia , Pereira Hélder , Roca Anna Anglisano , Coupechoux Guillaume , Juan Xavier
Published: February 2023

The Geoscience Education Field Officers (GEFO) programme, launched in 2019 by the European Geosciences Union (EGU) Committee on Education (CoE), began in six countries (France, India, Italy, Morocco, Portugal, and Spain) with the support of the International Geoscience Education Organisation (IGEO) and the International Union of Geological Sciences (IUGS). Due its success, the EGU Council has approved its extension and the increase of participating countries for the current and upcoming years. Thus, a call was open and CoE received thirty-four teacher’s applications from twenty-two countries belonging to Asia, Africa, Europe, and South America. After a selection process, thirteen new GEFOs were appointed to represent Albania, Burkina Faso, Chile, Colombia, Estonia, Germany, Greece, India, Malaysia, Romania, Togo, Turkey, and the United Kingdom. As all the first GEFOs, the new ones are qualified and experienced geosciences teachers from different levels (Primary, Secondary and Higher education) and/or engaged and committed with Geosciences educational issues. In May 2022, the new GEFOs met in Barcelona for a face to face two-days training session organized and promoted by the ‘old’ GEFOs from Italy, France, Portugal, and Spain, and by their supporters (national teachers who help GEFOs in their role) from Portugal and Spain. The main goal of this training was to introduce the fundamental tool of the GEFO programme – the Earthlearningidea repository of teaching resources (www.earthlearningidea.com) - and provide them with the necessary skills to offer professional development to the teachers in their countries. During this two-days training, the new GEFOs assumed the role of teachers and performed several proposed hands-on activities. This method has allowed them to prepare themselves for their new role by first-hand knowing the activities and sharing knowledge and difficulties with their fellows      but, also, to recognize the barriers that the future attendant teachers can face in the workshops organized by GEFOs. So far, the GEFO team includes nineteenth members from eleven European (the EGU GEFOs) and eight non-European countries (the IGEO/IUGS GEFOs), working as an international network to promote geoscience education in an innovative and global way. In the future, the success of GEFOs programme could justify its expansion to other countries.
Investigating sediment transport in karst using hydrograph unmixing, sediment transport modeling and multi-source hysteresis
Authors: Bettel Leonie , Fox James , Husic Admin , Mahoney Tyler , Marin Arlex , Zhu Junfeng , Tobin Ben , Al Aamery Nabil
Published: February 2023

Karst characterizes almost 15% of the worlds terrain, however the mechanics of sediment transport and its prediction in karst river and cave systems remains underdeveloped. Hysteresis analysis has recently been used more to investigate the behaviors of sediments during storm events in surface systems and to some extent in karst systems. Historically, clockwise and counter-clockwise hysteresis typically refer to proximal and distal sourcing for streams. For karst systems, clockwise and counter-clockwise hysteresis has been identified to refer to an saturated and unsaturated aquifer prior to the event.However, most interpretation of hysteresis assumes a single dominant water source, for example runoff, and assumes that baseflow is not contributing to the sediment load. One aspect of sediment hysteresis and its interpretation that has received less attention is the occurrence of several, significant water sources, eroding and delivering sediment to the watershed outlet. It is common for both surface stream systems  and karst subsurface systems to have multiple water sources contributing to the total sediment load. Each of the sources carries their own sediment time distribution, and often lead to complex hysteresis looping behavior after mixing. The primary goals of this work are to (1) study how the complex source water-sediment mixing processes impact hysteresis results and (2) to carry out solutions to the water-sediment mixing processes for karst streams, caves, and springs and show the utility and uncertainty of the method.Several high-resolution sensors have collected data at a karst spring in central Kentucky, USA, for a 2.5 year period. Water unmixing was performed using electrical conductivity as a tracer to separate the groundwater from the surface water and infer sediment sources. Theoretical analyses have shown that not only timing and magnitude of sedigraphs influence the result of the hysteresis loops, but also timing and magnitude of each of the multiple water sources have a strong effect on the resulting hysteresis loop. The groundwater flow shows to have dominant counter-clockwise hysteresis loop, surface water shows to have clockwise loops dominating. Depending on the timing and magnitude of the water sources, the hysteresis loop at the karst spring varies from strictly counterclockwise, to a figure-8 loop, to a complex pattern.
Diagnosing above- and below-canopy temperature impacts of forest in the Netherlands during heatwaves
Authors: Zhou Jingwei , Teuling Adriaan J. , van der Molen Michiel K.
Published: February 2023

Heatwaves have significant effects on ecosystems and human populations. Human habitability is impacted severely as human exposure to heatwaves is projected to increase. Future risk of heatwaves has demonstrated the need of effective measures for adaptation to persistent hot temperature extremes and ambitious mitigation to limit further increases in heatwave severity.At local scales, forest management could be a potential approach of modifying surface energy budget and in this way alleviating heatwave impacts. In this study,  open-site, below-canopy, and above-canopy climatic conditions from 4 different sites during the time period 1997-2020 in the Netherlands were compared to investigate canopy functions of affecting above-canopy macroclimate and as a thermal insulator to regulate understory microclimate and land surface ecology. Using high-resolution sub-daily data sets from Loobos, in which water vapor and heat fluxes were measured every half an hour by a combination of eddy covariance flux measurements and a profile system, we analysed temperatures at three levels of Loobos (23.5m, 7.5m, and soil litter layer) of the same profile and compared them with those measured at open sites in De bilt and Deleen.Heatwave periods are defined as a sequence of at least five days during which the daily maximum temperature exceeds the climatological mean over the reference period 1997-2010 by at least 5 °C. During heatwave periods, the cooling effects of the canopy on surface temperatures are stronger compared to normal periods while the canopy may aggravate the temperature above it during certain hours. By contrast, temperature differences are higher during normal times than heatwave periods when considering temperature buffer effects of canopy on understory climate (7.5m).Further study on heat fluxes, Bowen ratio, and canopy effects on heat stress during normal conditions and heatwaves will be conducted as well. Relative humidity will be incorporated in measuring heat stress to reflect real conditions living bodies experience.
The late Maastrichtian calcification crisis in Bidart (France): a benthic environment perspective
Authors: Patra Subham , Kesen Kebenle , Punekar Jahnavi
Published: February 2023

The final ~0.5m interval of the Cretaceous-Paleogene (K-Pg) boundary at Bidart (France) constitutes the “Deccan benchmark” interval characterized by taphonomic and geochemical proxies of ocean acidification linked with Deccan volcanism. Planktic foraminifera census and morphometric data reveal a concurrence of dwarfed species, thinner test walls, high test fragmentation of planktic foraminifera and increased relative abundance of Guembelitria spp. Together, these evidences point toward severe biotic stress and a likely calcification crisis in planktic foraminifera in the final ~0.5m (~58 ky) of the late Maastrichtian at Bidart.In the sediment-water interface, the benthic foraminiferal assemblage increase to a dramatic >100,000 tests/gram, indicating a sediment-starved horizon at the KPB. Interestingly, a sharp increase in the relative proportion of heavily calcified genera like Cibicidoides spp. (~51%), Steinsioeina spp. (~10%) and Coryphostoma spp. (~9%) is also recorded at the KPB. The taphonomic angle to such a record is rejected as the benthic foraminifera fragmentation index does not record the ‘acidification’ event as significantly. Similarly, morphometric analysis reveals average sizes of thick-walled genera like Cibicidoides spp., Steinsioeina spp., Gyroidinoides spp., Praebulimina and Coryphostoma spp. increasing at the KPB and ~0.3m below it. A possible explanation for such a biotic advantage for the individuals building heavily calcified tests could be a carbonate super-saturation led by the extinction of pelagic calcifiers at the KPB. In the benchmark, rare occasions of dwarfing and reduced absolute abundances of calcareous benthic foraminifera imply a lower degree of environmental stress. Similarly, census analysis of agglutinated benthic foraminifera records an increased population within the benchmark, indicating a change in community structure.  Whether such a change is a response to acidification or an artifact of preservation is currently under investigation. Our results support an acidification that was restricted to the surface ocean and resulted in severe (planktic) crisis, with limited effect on benthic foraminifera. This is consistent with a lack of benthic foraminifera extinctions across the K-Pg boundary.
Surface ozone trends and precursor attribution in South America
Authors: Seguel Rodrigo , Castillo Lucas , Opazo Charlie , Rojas Néstor , Nogueira Thiago , Cazorla María , Gavidia Mario , Gallardo Laura , Elshorbany Yasin , Menares Camilo
Published: February 2023

Several Working Groups have been established within the frame of the second phase of the Tropospheric Ozone Assessment Report (TOAR-II). The Tropospheric Ozone Precursors focus Working Group (TOP WG) aims to examine the current regional and global distribution, variability and trends of ozone precursors. Part of our strategy has been to analyze in greater detail different regions of the globe. In particular, this work addresses South America, a region characterized by densely populated urban areas with high air pollution levels.We use data from air quality monitoring networks that measure surface-level ozone, nitrogen oxides, carbon monoxide and meteorological variables. To date, we have validated and incorporated monitoring stations from Brazil (51), Chile (18), Colombia (13) and Ecuador (6) into our central database. To evaluate short- and long-term ozone exposure, we use the maximum daily 8-hour average (MDA8) and the peak season guideline proposed by the World Health Organization (WHO) set at 51 and 31 ppbv, respectively. We applied the Quantile Regression (QR) method to analyze ozone and precursor network trends. We also identified points in time series that mark changes in trends through a piecewise function.The highest MDA8 ozone for 2015-2021 was found in São Paulo (52 ppbv) and Santiago (51 ppbv). In São Paulo, the short-term ozone exposure decreased by 7% compared to the average of the years prior to 2015 (period analyzed in TOAR phase I), while in Santiago, it increased by 10%. In Bogota and Quito, the MDA8 complied with the WHO guidelines (33 and 32 ppbv, respectively). Similarly, the long-term ozone exposure guideline was exceeded in São Paulo (39 ppbv) and Santiago (40 ppbv), while Bogota (25 ppbv) and Quito (26 ppbv) complied. The trend analysis showed that Quito was the only city with a negative ozone trend of -0.10 ppb/year (50th percentile) for the analyzed period. In turn, the São Paulo trend increased after 2008 (0.43 ppbv/year), while Santiago and Bogota have increased since 2017 (0.93 ppbv/year and 1.3 ppbv/year, respectively). We highlight that the positive trend in Santiago is driven mainly by the high percentiles (>70th). Underlying processes that explain trends involve more efficient photochemical ozone formation (e.g., NO2/NOx trend) and meteorological factors.This ongoing work aims to include more South American cities and background stations already available in the new TOAR database. Finally, we will project ozone trends for the next decade using machine learning techniques (random forest) under precursor emission scenarios and temperature projections.
ERA5-Land: More than 7 decades of land surface consistency with timely updates
Authors: Munoz-Sabater Joaquin , Balsamo Gianpaolo , Buontempo Carlo , Burgess Samantha , Hersbach Hans , Hodkinson John , Mueller-Quintino Anna , Radu Raluca , Rozum Iryna , Villaume Sebastien
Published: February 2023

Reanalysis is a key activity within the Copernicus Climate Change Service (C3S), which is funded by the European Union Copernicus programme and implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF). Currently, the latest generation of European Reanalysis, ERA5 and ERA5-Land, are available through the C3S Climate Data Store (https://cds.climate.copernicus.eu/). ERA5 provides hourly snapshots of the Earth's atmosphere, land surface and ocean waves from 1950 to present, thus providing a global view of the evolution of the Earth’s climate without temporal or spatial gaps for the last seven decades. The land surface component, although part of the ERA5 portfolio, contains few inconsistencies. For instance, significant regional steps between different production segments are present, compromising the reliability of long-term trends. In addition, ERA5 does not provide sufficient resolution for a large and growing number of land applications.ERA5-Land was designed to overcome the above-mentioned shortcomings of the land branch of reanalysis. For instance, steps in the seam between production segments may be avoided by applying a long spin-up strategy for the initialization of each production segment. ERA5-Land is a unique dataset of its kind, providing a global scale description of the continental water and energy cycles through a series of 50 key surface variables, hourly at a spatial resolution of 9 km, from 1950 to present. ERA5-Land is driven by the near-surface meteorology of ERA5, and temperature is adjusted by considering the orographic differences between ERA5 and ERA5-Land numerical grids. The fidelity of ERA5-Land was assessed by comparing the main fields to a large number of available in-situ observations distributed along the world from 2000 onwards. The variables under analysis were soil moisture, snow depth, lake surface water temperature, river discharge, surface latent and sensible heat fluxes, and skin temperature. The results of the evaluation analysis suggested significant improvements of the ERA5-Land hydrological cycle in comparison to those of ERA5 and ERA-Interim.The number of ERA5-Land users is counted in thousands. Very recently and similarly to ERA5T, the ERA5-Land-T facility was enabled, which means that preliminary updates are made available daily with only 5-days delay with respect to real time. The final quality-checked product is published with 2-3 month delay with respect to real time. ERA5-Land-T is the result of a requirement of users needing more recent data and opens the door to new applications such as flood forecasting or biomass monitoring.In this paper the main characteristics of ERA5-Land dataset will be highlighted, its main strengths and weaknesses, as well as the current status.
Leaves, land-atmosphere interactions and extremes
Authors: Duveiller Gregory
Published: February 2023

Leaves are the main interface between terrestrial ecosystems and the atmosphere. They govern the exchange of carbon, water and energy between vegetation and the atmospheric boundary layer. They are the surface designed to capture light and transform it to sugars via photosynthesis, but they also regulate how much water they transpire through their stomata. Their colour, density and orientation will affect their albedo, which determines how much energy is reflected back to the atmosphere, while their overall configuration within the canopy structure can affect the roughness length of the surface.When we manage landscapes, be it by planting crops or cutting down forests, we are typically changing the quantity and type of leaves covering the surface of the land. By doing so, we can modify the land-atmosphere interactions and thereby have an effect on the climate. For instance, a substantial local cooling effect could be attained by using cover crops in winter, especially with highly reflective chlorophyll deficient mutants. Increasing forest cover appears to lead to more cloud cover, which itself could affect albedo at the top of the atmosphere. But the amount of leaves in the landscape can further affect extremes.Here I will illustrate how leaves affect land-atmosphere interactions in the context of extreme events with two studies. The first study looks at the known biophysical effect of land use change on local surface temperature, but extends it to explore its sensitivity across the globe during the extremes observed in 20 years of satellite remote sensing records. The second study shows how much getting leaves right matters within the reanalysis records of ERA5 and ERA5-Land, where prescribed seasonal cycles of leaf area index (LAI) lead to biases in modelling land surface temperature (LST), thereby underestimating the intensity of heat waves over Europe.
Cretaceous Uplift of the Transantarctic Mountains-Not Due to Rift-Flank Uplift
Authors: Huerta Audrey , Blythe Ann , Winberry Paul
Published: February 2023

The Transantarctic Mountains (TAM) form a >3000 km-long boundary between East and West Antarctica with extreme relief reaching to >4500 m in elevation. Proximity of the TAM to the Cretaceous/Paleogene West Antarctic Rift System (WARS) suggests a genetic relationship between development of the TAM and extension of West Antarctica. However, the details of this relationship remain elusive.Here we present the results of a low-temperature thermochronology study in the central TAM combined with numerical modelling of the thermal-kinematic crustal evolution. Sampling was undertaken along the ~100 km long, ~40 km wide Byrd Outlet that cuts through the TAM. We focus on the results of apatite fission track (AFT) analysis of seventeen samples collected along two near-vertical transects. All of these samples yield AFT ages of ~80 Ma. Transect A, located 45 km from the mountain front, has nine ~80 Ma samples along >1500 m of near-vertical relief (580-2140 m asl). Transect B is located 70 km from the mountain front, with eight ~80 Ma old samples along 700 m of near-vertical relief (450 m to 1150 m asl).These ~identical ages typically would be interpreted to indicate rapid cooling through the AFT partial annealing zone (PAZ; 120°C-60°C). However, inverse modeling (HeFTy) shows that the samples experienced slow cooling (~4°C/m.y.), with samples remaining within the AFT PAZ for 30-60 my. Thus, there appears to be an inherent contradiction between the instantaneous cooling at ~80 Ma and the very slow cooling. To explore this apparent contradiction we designed a finite-difference thermal-kinematic model to reconstruct the erosional/cooling history of the crust of the Byrd Outlet region. Successful simulations must predict three things: 1) a coherent 1500 m thick crustal section that passes through the AFT closure temperature (110°C) ± simultaneously (± 5my), 2) this crustal section then must remain in the AFT PAZ for greater than 15 my, and 3) the top of this crustal section is currently located 1300 m below the adjacent surface of the earth (below the current peak of Mt McClintock at 3490 asl).Modeling results confirm that successful simulations must include rapid incision of a km’s-deep gorge and the associated ± instantaneous cooling of the crustal section, followed by 10’s of millions of years of regional erosion and slow cooling through the AFT PAZ.These results provide constraints on the timing and mechanisms responsible for the uplift of the central TAM. Firstly, the region-wide 80 Ma ages reveals incision of high topography in the Cretaceous, ~coeval with development of the West Antarctic Rift System. Secondly, this development of high topography far inland from the mountain front is inconsistent with rift-flank uplift. Additionally, the deep incision indicates > 5 km of uplift, which exceeds the amount that could be reasonably assigned to just flexure plus crustal thickening or just flexure plus lithospheric 
Two-phase simulation of scour using a hybrid RANS-LES turbulence model
Authors: Gilletta de Saint Joseph Alban , Chauchat Julien , Bonamy Cyrille , Robert Marie
Published: February 2023

The coastal environment is meeting numerous anthropogenic changes especially with the increased implementation of bottom-fixed Offshore Wind Farms. Few feedbacks are available for these recent infrastructures facing a complex turbulent marine environment made of combined waves and currents. In the presence of a pile, strong hydrodynamical eddies structures form that are responsible for the scour process which may lead to the failure of the wind turbine. Former two-phase flow simulations of this problem [1] have been performed using the Reynolds-Averaged Navier-Stokes approach for turbulence modelling and they have shown some limitations to reproduce the main features of the scour process. Turbulence modelling was argued to be the major bottleneck. In order to further investigate this problem, an extensive study of the numerical simulation of the flow hydrodynamic around a wall-mounted cylinder has been carried out using a hierarchy of turbulence models including RANS, hybrid RANS-LES and LES. The range of Reynolds numbers is too large to allow for a well-resolved LES and therefore hybrid RANS-LES is essential to reproduce main hydrodynamical features at an affordable cost. In this study we evaluated the k-omega SST model coupled with the Improved Delayed Detached Eddy Simulation [2] and the Scale-Adaptative Simulation [3]. All the simulations have been performed using OpenFOAM an open-source Computational Fluid Dynamics toolbox. Our simulations suggest that the k-ω SST SAS is the best model for this configuration. It has been adapted for the two-phase flow Eulerian-Eulerian approach and implemented in sedFOAM [4]. Preliminary results of the two-phase simulation of Roulund and co-worker experiments [5] shows very encouraging results in terms of morphological features at short-time scales. These results will be presented during the conference together with in-depth analysis of the sediment transport fluxes.References[1] Nagel T., Chauchat J., Bonamy C., Liu X., Cheng Z. and Hsu T. - J., Three-dimensional scour simulations with a two-phase flow model, Advances in Water Resources (2020).[2] M. S. Gritskevich, A. V. Garbaruk, J. Schütze and F. R. Menter, Development of DDES and IDDES Formulations for the k-ω SST Model, Flow Turbulence Combust (2012).[3] F. R. Menter and Y. Egorov, A scale-adaptative simulation model using two-equation models, American Institute of Aeronautics and Astronautics Paper (2005).[4] J. Chauchat, Z. Cheng, T. Nagel, C. Bonamy, and T.-J. Hsu, Sedfoam-2.0: a 3-d two-phase flow numerical model for sediment transport, Geoscientific Model Development (2017).[5] Roulund A., Sumer B. M., Fredsøe J. and Michelsen J., Numerical and experimental investigation of flow and scour around a circular pile, Journal of Fluid Mechanics (2005).
Towards an Open Digital Twin of Soil-Plant System Following Open Science
Authors: Zeng Yijian , Alidoost Fakhereh , Schilperoort Bart , Liu Yang , Willem Grootes Meiert , Wang Yunfei , Song Zengjing , Yu Danyang , Tang Enting , Han Qianqian , van der Tol Christiaan , Zurita-Milla Raúl , Yang Michael Ying , Girgin Serkan , Dzigan Yifat , Su Zhongbo
Published: February 2023

Climate projections strongly suggest that the 2022 sweltering summer may be a harbinger of the future European climate. Climate extremes (e.g., droughts and heatwaves) jeopardize terrestrial ecosystem carbon sequestration. The construction of an open digital twin of the soil-plant system helps to monitor and predict the impact of extreme events on ecosystem functioning and could be used to recommend measures and policies to increase the resilience of ecosystems to climate-related challenges. A digital twin refers to a highly interconnected workflow, with a data assimilation framework at its core to combine observations and process-based models, meanwhile accompanied by an interactive and configurable platform that allows users to create and evaluate user-specific scenarios for scientific investigation and decision support. Creating an open digital twin means creating a digital twin following Open Science and FAIR principles, both for data and research software. In this contribution, the STEMMUS-SCOPE model was used as an example to develop an open digital twin of the soil-plant system. We suggest our recently developed open digital twin infrastructure could serve as the backbone for an interoperable framework to facilitate the digitalization of other Earth subsystems (e.g., by simply replacing the soil-plant model). In addition, we show how software not designed initially as open can be adopted to create an open digital twin using containers - standardized computational environments that can be shared, reused and that foster reproducibility.
Results from five-day GRACE/GRACE-FO mascon solutions from CSR
Authors: Save Himanshu , Tamisiea Mark , Hasan Emad , Sun Alexander , Rateb Ashraf , Scanlon Bridget
Published: February 2023

The Gravity Recovery and Climate Experiment (GRACE) and its Follow-On (GRACE-FO) missions have provided valuable insights in the fields of Hydrology, Oceanography, Cryosphere Sciences, Solid Earth etc. and improved our understanding of the changes in the Earth’s water cycle since 2002.While the temporal resolution of the official GRACE/GRACE-FO products is 30 days, this study aims to push those boundaries. This study focuses on the 5-day global mascon solution produced from GRACE/GRACE-FO satellite tracking data. This paper discusses the techniques used and challenges encountered with production of such a global total water storage and ocean bottom pressure product with high temporal sampling. Analysis is performed over hydrological and ocean basins to validate the higher frequency signals captured in this product. An important goal for the production of this higher temporal resolution GRACE/GRACE-FO product is to be able to use these signals with a latency of a few days for ingestion into automated machine learning algorithms for early flood detection applications.
Lightning in a changing climate and its impacts on fire area burned
Authors: Whaley Cynthia , Schumacher Courtney , Etten-Bohm Montana , Arora Vivek , Plummer David , Cole Jason , Lazare Michael , Akingunola Ayodeji
Published: February 2023

Lightning is an important atmospheric process for igniting forest fires – often in remote locations where they are not easily suppressed – which results in potentially large emissions of many pollutants and short-lived climate forcers. Lightning also generates reactive nitrogen, resulting in the production of tropospheric ozone, the third most important greenhouse gas. Furthermore, the changing climate is expected to change the frequency and location of lightning. As such, lightning is an important component of climate models. The Canadian Atmospheric Model, CanAM, is one such climate model that did not contain an 'online' lightning parameterization. Fire ignition in CanAM was done via an unchanging climatological lightning input. In this study, we have added a new logistical regression lightning model (Etten-Bohm et al, 2021) into CanAM, creating the capacity for future lightning predictions with CanAM under different climate scenarios. The modelled lightning and fire area burned were evaluated against measurements in a historical period with good results. Then we simulate lightning and fire area burned in a future climate scenario in order to provide an estimate on how lightning and its impacts will change in the future. This study also presents the first time that CanAM’s land fire model was used online with its atmosphere to fully simulate fires in the global earth system.Reference:Etten-Bohm, M., J. Yang, C. Schumacher, and M. Jun : Evaluating the relationship between lightning and the large-scale environment and its use for lightning prediction in global climate models, JGR-atmospheres, 126, e2020JD033990, 2021.
Signatures of catchment nonlinearity and nonstationarity, quantified using Ensemble Rainfall-Runoff Analysis
Authors: Kirchner James
Published: February 2023

It is almost axiomatic that catchment response to precipitation is nonlinear and nonstationary, implying that each drop of rain may affect streamflow differently, depending on how it fits into the sequence of past and future precipitation.  But do most catchments exhibit similar patterns of nonlinearity and nonstationarity, or not?  If not, which ones are more nonstationary (i.e., more sensitive to antecedent precipitation)?  Which ones are more nonlinear?  And why? Understanding catchments’ nonlinear and nonstationary behavior requires widely applicable tools for characterizing and quantifying that behavior in the first place. Here show how catchment nonstationarity and nonlinearity can be quantified using Ensemble Rainfall-Runoff Analysis (ERRA), a data-driven, model-independent method for quantifying rainfall-runoff relationships across a spectrum of time lags.  ERRA is superficially similar to classical unit hydrograph methods, but whereas unit hydrographs assume linearity (runoff response is proportional to precipitation) and stationarity (runoff response to a given unit of rainfall is identical, regardless of when it falls), ERRA can explicitly quantify the nonlinearity and nonstationarity in rainfall-runoff relationships, directly from data.  This approach combines least-squares deconvolution (to un-scramble each input's temporally overlapping effects) with demixing techniques (to separate the effects of individual inputs, or inputs occurring under different antecedent conditions) and broken-stick regression (to quantify nonlinear dependencies). Not only can this approach quantify the impulse response of streamflow to precipitation, it can also quantify how this impulse response changes with rainfall rates (nonlinearity), how it varies with catchment wetness (nonstationarity), and how it differs for rain falling on different parts of the landscape (heterogeneity), even if these signals are all overprinted on one another at the catchment outlet.  Results from this approach may be informative for catchment characterization and runoff forecasting; they may also lead to a better understanding of short-term storage dynamics and landscape-scale connectivity.  Applications of these methods will be illustrated using large multi-catchment data sets from Switzerland and North America.
Sample Path Large Deviations for Climate, Ocean, and Atmosphere
Authors: Grafke Tobias
Published: February 2023

Rare and extreme events are notoriously hard to handle in any complex stochastic system: They are simultaneously too rare to be reliably observable in numerics or experiment, but at the same time too important to be ignored if they have a large impact. This is a particular complication in climate science, atmosphere and ocean dynamics that deals with a large number of strongly coupled degrees of freedom. Often these rare events come in the form of a stochastically induced transition between different viable macrostates. Examples include atmospheric jets, oceanic currents, etc, that correspond to large coherent structures which are long live-lived, but might ultimately disappear. In this talk, I discuss rare events algorithms based on instanton calculus and large deviation theory that are capable of computing probabilities of such transitions happening, as well as their most likely pathway of occurrence.
Integration of a deep-learning-based fire model into a global land surface model
Authors: Son Rackhun , Carvalhais Nuno , Silva Lazaro , Requena-Mesa Christian , Weber Ulrich , Gayler Veronika , Stacke Tobias , Schnur Reiner , Nabel Julia , Winkler Alexander , Zaehle Sönke
Published: February 2023

Fire is an ubiquitous process within the Earth system that has significant impacts in terrestrial ecosystems. Process-based fire models quantify fire disturbance effects in stand-alone dynamic global vegetation models (DGVMs) and within coupled Earth system models (ESMs), and their advances have incorporated both descriptions of natural processes and anthropogenic drivers. However, we still observe a limited skill in modeling and predicting fire at global scale, mostly due to the stochastic nature of fire, but also due to the limits in empirical parameterizations in these process-based models. As an alternative, statistical approaches have shown the advantages of machine learning in providing robust diagnostics of fire damages, though with limited value for process-based modeling frameworks. Here, we develop a deep-learning-based fire model (DL-fire) to estimate gridded burned area fraction at global scale and couple it within JSBACH4, the land surface model used in the ICON ESM. We compare the resulting hybrid model integrating DL-fire into JSBACH4 (JDL-fire) against the standard fire model within JSBACH4 and the stand-alone DL-fire results. The stand-alone DL-fire model forced with observations shows high performance in simulating global burnt fraction, showing a monthly correlation (Rm) with the Global Fire Emissions Database (GFED4) of 0.78 and of 0.8 at global scale during the training (2004-10) and validation periods (2011-15), respectively. The performance remains nearly the same when evaluating the hybrid modeling approach JDL-fire (Rm=0.76 and 0.86 in training and evaluation periods, respectively). This outperforms the currently used standard fire model in JSBACH4 (Rm=-0.16 and 0.22 in training and evaluation periods, respectively) by far. We further evaluate the modeling results across specific fire regions and apply layer-wise relevance propagation (LRP) to quantify importance of each predictor. Overall, land properties, such as fuel amount and water contents in soil layers, stand out as the major factors determining burnt fraction in DL-fire, paralleled by meteorological conditions, over tropical and high latitude regions. Our study demonstrates the potential of hybrid modeling in advancing the predictability of Earth system processes by integrating statistical learning approaches in physics-based dynamical systems.
Molybdenum Isotope Systematics of the Kamchatka Subduction Zone System
Authors: Willbold Matthias , Wörner Gerhard
Published: February 2023

Molybdenum (Mo) isotopes in magmatic rocks are a promising tool in high-temperature isotope geochemistry. In particular, basalts from subduction zones that are geochemically controlled by mass transfer through slab-fluid addition have systematically higher δ98Mo values (i.e. measured 98Mo/95Mo ratio in a sample relative to that in a standard) than the depleted mantle (δ98Mo = –0.21‰). In these rocks, the elevated δ98Mo values are linked to high Pb/Ce and high (238U/230Th) ratios and can be reconciled by the addition of isotopically heavy Mo via a slab fluid component1,2. So far, these systematics are best expressed in subduction zone basalts from the Mariana and Izu arc systems that also form coherent mixing trends between fluid-enriched mantle domains in δ98Mo versus 143Nd/144Nd and 176Hf/177Hf space1,2.The Kamchatka arc system represents the northernmost expression of the W-Pacific convergent margin. Volcanic front lavas are dominated by slab-to-mantle mass transfer through fluid transport, whereas subduction of the Emperor seamount ridge gives rise to back-arc basalts with a geochemical and isotopic affinity to within-plate basaltic rocks3.Here, we report δ98Mo data for 47 basalts from an E-W transect across the Kamchatka peninsula that have previously been analysed for their major, trace element, radiogenic and stable isotope data. The δ98Mo data extent the trend defined by samples from the Marianas and Izu arcs starting from moderately high δ98Mo and Pb/Ce values towards sub-depleted mantle δ98Mo and mantle-like Pb/Ce ratios that indicate the presence of a source component formed by partial melts of a rutile-bearing mafic crust4.The common geochemical and isotopic trends formed by the combined Mariana – Izu – Kamchatka datasets suggest a surprisingly uniform Mo isotope composition of a subduction zone fluid endmember for more than 5000 km along-strike of the Circum-Pacific subduction zone system. Our data also confirm the presence of an enriched source component in the Kamchatka mantle wedge, possibly originating from the subducted Emperor seamount chain5.1Freymuth, H., et al., EPSL 432, 176-186 (2015). 2Villalobos-Orchard, J., et al., GCA 288, 68-82 (2020). 3Churikova, T., et al. JPet 42, 1567-1593 (2001). 4Chen, S., et al., Nat. Comm. 10, 4773 (2019). 5Shu,Y., et al.,Nat. Comm. 13, 4467 (2022).
Classifying sea ice in high-resolution SAR imagery using deep learning
Authors: McDonald Andrew , Dimasaka Joshua , Plumridge Meghan , Torry Jay , Zúñiga González Andrés Camilo , van Zeeland Louisa , Rogers Martin , Hosking Scott
Published: February 2023

Sea ice plays a vital role in Earth’s human-climate system. It regulates the Earth’s overall energy balance by seasonally increasing surface albedo and reflecting solar radiation; it governs thermodynamic exchanges between the ocean and atmosphere and thereby impacts mid-latitude weather patterns; it buttresses key continental ice shelves in Greenland and Antarctica; it provides an ecosystem in which land, marine, and airborne species thrive; it enables the livelihoods of indigenous populations across the Arctic; it poses a major obstacle to global shipping logistics; and it serves as a key indicator of climate change given the sensitivity of the polar regions to anthropogenically-induced warming. Regular and automated monitoring of sea ice concentration and type may therefore prove valuable to a broad and diverse set of parties. Conventional approaches in sea ice monitoring involve the use of remotely sensed microwave radiometer data with low resolution of 6-25 km and high instrumental sensitivities to environmental factors such as atmospheric water vapour, near-surface brightness temperature, and wind-induced surface roughening. Dual-polarity synthetic aperture radar (SAR) imagery offers a higher resolution alternative, which can also distinguish between sea ice and open water year-round independent of weather conditions. However, manual interpretation of such imagery is time-consuming. In this work, we develop a deep learning system to automatically generate high-resolution maps of sea ice concentration and type using 40m-resolution SAR imagery obtained from the Sentinel-1 mission between 2017 and 2021. Focusing on the East Weddell Sea, a region where compacted sea ice is renowned for inhibiting ship navigation and an active area of iceberg calving, we train the system against reference sea ice charts produced through manual interpretation by experts. We identify strengths and weaknesses of the system and discuss implications for future research at the intersection of machine learning and polar science.
A nine-year, airborne laser scanning archive of glacier change, western Canada.
Authors: Menounos Brian , Heathfield Derek , Beffort Steve , Viner Nick , Gonzalez Arriola Santiago , White Rob
Published: February 2023

Western Canada contains 72% of the glaciers within the Randolph Glacier Inventory (RGI) region 2 (Western Canada and USA), and these glaciers constitute 95% of the region’s total ice cover. Recent studies exploiting stereoscopic imagery from NASA’s Terra satellite (ASTER) have reduced biases in the number, type and distribution of glaciers used to assess regional glacier mass change. The elevation uncertainty of ASTER digital terrain models, in addition to infrequent sampling, confounds its use to detect trends in elevation change at seasonal scales or for small glaciers (< 1km2). Since summer 2014, the Hakai-UNBC Airborne Coastal Observatory (ACO) routinely acquires laser altimetric data at the end of the accumulation (late-April to early May) and ablation (early to late September) over many of western Canada’s glaciers and icefields using an aircraft equipped with an 1064-nm laser scanner and dedicated positional hardware. Post-processed uncertainties of repeated, co-registered elevational data over stable terrain yield uncertainties that are typically below ±0.3 m (±1s). Since 2020, our bi-annual acquisitions sample over 800 glaciers (about 2,000 km2), which constitutes about 15% of the total areal extent of ice in RGI-02. While the area-altitude distribution of ACO sampled glaciers largely accord with those of RGI-02, our sampling program captures fewer glaciers that exist at highest elevations, and the average glacier size surveyed by us is about three times larger than the average glacier size within RGI-02 (0.77 km2). Our archive reveals important aspects of glacier elevation change that cannot be obtained from existing publicly available sources of digital terrain data such as the magnitude of seasonal to inter-annual changes during the accumulation and ablation seasons, short-term horizontal transfers of mass, changes in volume and extent of transient late-lying snow, and the effects of short-term meteorological events (e.g. heat waves or forest fires) on regional melt events for a given year. We plan to release this archive to the public so it can be used to validate in-situ mass balance measurement programs, improve melt models and provide insight into physical factors that drive glacier change.
Preliminary observations on the Halophila stipulacea resilience to thermal stress at the northern tip of the Red Sea, Jordan
Authors: Wahsha Mohammad , Al-Najjar Tariq
Published: February 2023

The present study aimed to evaluate the implementation of the biomarkers: Lipid Peroxidation (LPO) and Lactate Dehydrogenase (LDH) assays as an early warning tool for monitoring seagrass health status in relation to global and local environmental change in the Gulf of Aqaba, Jordan. To reach our objectives, we have developed a novel Seagrass Rack Semi-Automated Stress System (SR-SASS) to achieve comparable, short-term heat stress assays. The system consisted of twelve 15-L flow-through tanks that allowed the running of six independent temperature experiments simultaneously. The selected thermal stress assays: LPO and LDH, were adopted to collect an entire observation regarding the biological response of seagrass to thermal stress. The seagrass samples (Halophila stipulacea) were collected from quadrats measuring 0.25 m2 placed 50 m apart along three transects at the Marine Science Station (MSS, a protected area with no anthropogenic impact) from a depth of approximately 15 m. The samples were immediately transferred to the aquaculture unit at the MSS and incubated in a monitored aquarium filled with artificial seawater with a salinity of 40.0 ± 0.5 psu and pH value of 8.0 ± 0.1. Furthermore, seagrass samples were randomly distributed over the SR-SASS, including two replicate tanks per temperature treatment. Consequently, all samples were kept at 25 °C overnight; and, the control tanks remained at 25 °C, and the treatment tanks were subjected to heat stress as (T1) Mild: (temp. 27 °C), (T2) Moderate (temp. 33 °C), and (T3) Extreme (temp. 35 °C) for one hour. Temperature profiles were successfully controlled across experiments. Our results showed that the control group exhibited normal LPO levels (0.124 μM/g). There was a significant increase in the LPO level in seagrass leaf homogenate from the treated groups by 4-fold in the case of T2 and 6-fold in the case of T3 compared with those of the control group (P<0.05). However, no significant increase was observed in T1 (P>0.05). Similar findings were noted regarding the LDH activity levels. A further increase was shown as 73.12 and 83.34 U/mL in the case of T2 and T3, respectively, compared to control (19.84 U/ml) as reflected in the elevation of malondialdehyde values which appear temperature-dependent. Moreover, our results demonstrate that the seagrass (H. stipulacea) shows above-average physiological thermal tolerance in different experimental exposures. H. stipulacea exhibits resilience to 7 °C above the maximum summer means temperatures. Our findings provide novel information on the effects of elevated temperature on the resilience of seagrass exposed to short-term heat stress challenges. Keywords: Halophila stipulacea; Global warming; Gulf of Aqaba
Unraveling Regional Patterns of Sea Level Change over the Altimeter Era
Authors: Nerem R. Steven , Karnauskas Kristopher , Fasullo John , Hamlington Benjamin
Published: February 2023

Satellite altimeters have measured the global mean and regional patterns of sea level change since 1993 with impressive detail and precision. While the global mean rate of sea level rise has been studied extensively and is readily linked to global water budgets, the regional patterns (or deviations from the global mean) are subject to diverse physical mechanisms that span the gauntlet of internal climate dynamics, and models suggest a nuanced relationship to radiative forcing (greenhouse gases, aerosols, etc.). To date, little attempt has been made to synthesize the regional patterns of sea level change across the global ocean with a common diagnostic framework. Here we combine oceanic and atmospheric observations and leverage ensembles of a state-of-the-art global climate model to unravel the mechanisms governing the basin-scale patterns of sea level change around the world ocean. By applying some bedrock principles of physical oceanography and coupled dynamics, we find a leading role for wind forcing—Ekman and Sverdrup dynamics together yield faithful reproductions of the large-scale structure of sea level change from the tropics to the midlatitudes. We argue that the global pattern of sea level rise since 1993 is set, to leading order, by changes in the wind-driven ocean circulation and their influence on sea surface height via ocean heat divergence. Importantly, wind-driven needn’t be synonymous with internal variability—indeed, much of the observed global pattern is recovered by global climate models subject to historical anthropogenic forcings, and single-forcing experiments enable further insight into which forcings are responsible for which regional phenomena. As we move forward into the uncertain future, a better understanding of the causes of regional rates of sea level rise, including distinguishing which features are driven by human activities versus modes of natural variability—or both, is critical for the successful adaptation of humanity and its infrastructure to a rapidly changing climate.