bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of the gully morphology measurement method based on UAV photogrammetry
Authors: Yang Ji , Dong Yifan , Huang Jiangcheng
Published: March 2022

How to use a suitable method to accurately measure gully morphology is very important in the study of gully erosion monitoring and development, and the development of Unmanned Aerial Vehicle (UAV) has made it easy to apply UAV photogrammetry techniques to gully erosion studies. The aim of this study is to evaluate the accuracy of data and the efficiency of data processing by analyzing the errors of different schemes, and to provide suitable plan design ideas for the study of gully by UAV. Gully is the object of study and different flight schemes and Ground Control Point (GCP) placement schemes are used to acquire and process the data, and finally the errors are analyzed by Digital Surface Model (DSM) and orthophoto. Among all the schemes, the one with a flight altitude of 30m, 80%/70% photo overlap and 11 GCPs had the highest accuracy (Mean absolute error of 0.0353m and root mean square error of 0.0525m), but this scheme took more data collection and processing time and was less efficient. The number of GCPs and the placement location also have a significant impact on the accuracy，the position closer to the GCPs has a smaller error，and this study proves that the number of GCPs should not be more than 9 and should be evenly distributed in different parts of the gully.. When the flight altitude is 70m, the overlap is not less than 50%/40%, and the number of control points is 6, both accuracy and measurement efficiency can be taken into account at the same time. In addition, the sources of errors and the distribution locations of checkpoints with high errors were analyzed in four aspects: shadow, slope gradient, slope direction and vegetation. The use of UAVs in gully erosion studies is very convenient to get the later products with centimeter-level accuracy, and based on the results of the study we suggest that the flight altitude and photo overlap can be appropriately reduced when designing the scheme, and the number of GCP can be increased in the areas that need to be focused on and the areas with large elevation changes. At the same time, flight safety, UAV battery power, data collection efficiency and processing efficiency should be considered comprehensively.
Building sustainable and resilient societies: An online training course to enhance natural hazard scientists’ contribution to disaster risk reduction
Authors: Mohadjer Solmaz , Gill Joel C. , Taylor Faith E. , Jay Caitlin
Published: March 2022

Natural hazard scientists can contribute to the planning and development of sustainable and resilient communities through improved engagement in disaster risk reduction (DRR). Yet many scientists are uncertain of the steps they can take to effectively integrate their work into DRR. To address this challenge, we have developed an online, self-led training course designed for students and researchers interested in strengthening their engagement in DRR. The content of this online training course is based on a paper published in Natural Hazards and Earth System Sciences (doi.org/10.5194/nhess-21-187-2021) and involved a peer feedback process in the development of each module. There are seven learning modules on the following topics: (1) multi-hazard environments, (2) effective partnerships, (3) stakeholder engagement, (4) cultural understanding, (5) equitable access to hazard information, (6) people centered DRR, and (7) DRR and sustainable development. Each module includes asynchronous video lectures, practice exercises, self-assessment tools and feedback mechanisms, and interviews with experts. While the course is designed for natural hazard researchers, it incorporates a variety of teaching and learning strategies to support a wide range of users including decision makers, practitioners and university students to contribute more effectively to the integrated work needed to improve DRR activities. The course is open-access and will be launched in May 2022 at https://www.open.edu/openlearncreate/course/view.php?id=7993. Development of this course was supported by the EGU Training School Fund.
Comparison of the ground-level ozone between Europe and Southeast Asia as simulated with a global-regional model
Authors: Kilian Markus , Mertens Mariano , Joeckel Patrick , Kerkweg Astrid , Grewe Volker
Published: March 2022

Non-traffic (i.e. households, industry, etc.) emissions and land transport emissions are important anthropogenic precursors of tropospheric O3 and affect the air quality and contribute to global climate change. In order to improve air quality and mitigate climate change, robust knowledge of the amount of O3 formed by different emission sources is required. This study investigates the contributions of the different emission sectors to the ground-level ozone budget in Europe and Southeast Asia. For the present study we applied the MECO(n) model system, which couples the global chemistry-climate model EMAC on-line with the regional chemistry-climate model COSMO-CLM/MESSy. We used MECO(n) with a source apportionment method for ozone to investigate regional differences of the contributions from different emissions to ground-level ozone. Our findings show that contributions from anthropogenic non-traffic emissions to ground-level ozone are larger in Southeast Asia than in Europe. The contrary applies for the land transport emissions, which are more important in Europe compared to Southeast Asia. 
Global Sensitivity Analysis for a MACRO Meta-Model for Swedish Drinking Water Abstraction Zones
Authors: Pohlert Thorsten , Reichenberger Stefan , Multsch Sebastian , Jarvis Nicholas , Gönczi Mikaela
Published: March 2022

In Sweden farmers are legally obliged to apply for permits for pesticide use if their land lies within a drinking water abstraction zone. The standalone modelling tool MACRO-DB 4 developed by the Swedish University of Agricultural Sciences (SLU) is available for risk assessment and decision support. MACRO-DB 4 is used by local authorities, farmers/landowners and consultants, and is based on the well-established leaching model MACRO 5.2. However, the software is costly to maintain and slow for end users. Hence, a robust meta-model of MACRO-DB 4 was developed and integrated in a web-based tool (MACRO DB Steg2 v.5) that is fast, easy to maintain, and easy to understand for stakeholders. The meta-model (implemented as an R package) is based on i) a large number of MACRO simulations for the whole agriculturally relevant area of Sweden, and ii) a trilinear interpolation tool. The simulations comprised 18 climates, 72 soils, 1 typical crop (spring cereals), 3 application seasons (spring, summer and autumn), and 150 dummy compounds consisting of a grid of normalized Freundlich coefficient Koc, degradation half-life at reference conditions DT50 and Freundlich exponent. Target variables were i) the mean leaching flux concentration over 20 years at 2 m depth (PECgw), and ii) the 20-year mean concentration in large surface water bodies (PECsw; based on pesticide inputs via drainage and baseflow) . The meta-model performs a trilinear interpolation (in the three-dimensional space of Koc, DT50 and Freundlich exponent) for log10 of PECgw or PECsw, respectively. Different crops are taken into account in the web-based tool by adjusting the pesticide interception fraction according to the BBCH stage of the crop to be modelled at the time of application. In order to identify the most important input factors for PECgw and PECsw, a variance-based Global Sensitivity Analysis (GSA) was performed for the MACRO meta-model using the Sobol’ method. This method allows to i) identify first-order (direct) and higher-order (interaction) effects for each input factor (climate, soil, application season, Koc, DT50 and Freundlich exponent), and ii) rank the input factors according to their importance.
Four-dimensional temperature, salinity and mixed layer depth in the Gulf Stream, reconstructed from remote sensing with physics-informed deep learning.
Authors: Pauthenet Etienne , Bachelot Loïc , Tréguier Anne-Marie , Balem Kevin , Maze Guillaume , Roquet Fabien , Fablet Ronan , Tandeo Pierre
Published: March 2022

Despite the ever-growing amount of ocean's data, the interior of the ocean remains poorly sampled, especially in regions of high variability such as the Gulf Stream. The use of neural networks to interpolate properties and understand ocean processes is highly relevant. We introduce OSnet (Ocean Stratification network), a new ocean reconstruction system aimed at providing a physically consistent analysis of the upper ocean stratification. The proposed scheme is a bootstrapped multilayer perceptron trained to predict simultaneously temperature and salinity (T-S) profiles down to 1000m and the Mixed Layer Depth (MLD) from satellite data covering 1993 to 2019. The inputs are sea surface temperature and sea level anomaly, complemented with mean dynamic topography, bathymetry, longitude, latitude and the day of the year. The in-situ profiles are from the CORA database and include Argo floats and ship-based profiles. The prediction of the MLD is used to adjust a posteriori the vertical gradients of predicted T-S profiles, thus increasing the accuracy of the solution and removing vertical density inversions. The root mean square error of the predictions compared to the observed in situ profiles is of 0.66 °C for temperature, 0.11 psu for salinity and 39 m for the MLD.
The prediction is generalized on a 1/4° daily grid, producing four-dimensional fields of temperature and salinity, with their associated confidence interval issued from the bootstrap. The maximum of uncertainty is located north of the Gulf Stream, between the shelf and the current, where the variability is large. To validate our results we compare them with the observation-based Armor3D weekly product and the physics-based ocean reanalysis Glorys12. The OSnet reconstructed field is coherent even in the pre-ARGO years, demonstrating the good generalization properties of the network. It reproduces the warming trend of surface temperature, the seasonal cycle of surface salinity and presents coherent patterns of temperature, salinity and MLD. While OSnet delivers an accurate interpolation of the ocean's stratification, it is also a tool to study how the interior of the ocean's behaviour reflects on the surface data. We can compute the relative importance of each input for each T-S prediction and analyse how the network learns which surface feature influences most which property and at which depth. Our results are promising and demonstrate the power of deep learning methods to improve the predictions of ocean interior properties from observations of the ocean surface.
Investigating the diurnal radiative, turbulent and biophysical processes in the Amazonian canopy-atmosphere interface by combining LES simulations and observations
Authors: Vila-Guerau de Arellano Jordi , Pedruzo-Bagazgoitia Xabier , Moene Arnold , Ouwersloot Huug , Gerken Tobias , Machado Luiz , Martin Scot , Patton Edward , Sorgel Matthias , Stoy Paul , Yamasoe Marcia
Published: March 2022

We investigate the diurnal variability in and above the Amazonia rainforest for a representative day during the dry season period. We combine high-resolution large-eddy simulations constrained and evaluated against a comprehensive observations gathered during the field experiment GOAMAZON14.

Our findings quantified the large variability of the photosynthesis drivers in the canopy. This leads to a large scatter on the values of the leaf conductance with minimum and maximum values that vary more than 100% from the average value. The impact of turbulence on the fluxes of heat, moisture and carbon dioxide differs: at the canopy top, we found more strike structures related to wind at the canopy-atmosphere interface whereas at the canopy bottom the structure remind the ones of convective cells. In systematically comparing with the observations, we find that the agreement with observations depend very much on the variable. We find the best spatiotemporal agreement with variables related to wind. The heat distribution and fluxes compare also satisfactorily with the observations. The increasing of complexity on the biophysical processes, related to ecophysiology and soil and the atmospheric control, leads to the largest disagreement between observations and simulation results for evaporation, carbon dioxide plant assimilation and soil efflux. Though the model is able to capture the correct dependences, the magnitude still differ.  We discuss here the need to revise and adjust the leaf and soil models as well as to set a more comprehensive observational strategy to advance our understanding at leaf and canopy levels, and their coupling with the atmosphere.

 
Double-diffusive convection in two-layered sorbing porous media
Authors: Kolchanov Nikolay , Kolchanova Ekaterina
Published: March 2022

We study double-diffusive convective instabilities in a two-layered porous medium saturated with the mixture made up of a carrier fluid and solid nanoparticles. The latter ones are considered as solute particles. The two horizontal porous sublayers have distinct permeabilities. They are allowed to be heated either from above or from below in the presence of the gravitational field. A maximal solute concentration is at the upper boundary of the layered porous medium but zero concentration is set at the opposite lower boundary. One gets favorable conditions for the excitation of double-diffusion convection over the solutal and thermal profiles in the medium.

One considers the anisotropic porous medium as a reactive system, which can absorb nanoparticles. So, mixture transport is accompanied by the immobilization of solute particles. This process is described by the mobile/immobile media model, which takes into account the nonlinear kinetic equation for mixture redistribution between the mobile (moving with the carrier fluid) and immobile (sticking to the porous matrix) phases. The equations for convective flows in each of the porous sublayers are written within the Boussinesq approximation. The equations are solved numerically by the shooting method.

The clogging effect on the onset of thermosolutal convection has been investigated under the non-isothermal conditions. The bimodal marginal stability curves are plotted at different fixed values of the buoyancy ratio. This ratio includes the variations of mixture density due to thermal and solutal differences across the layered porous system. Stability maps for the system with the upper highly permeable sublayer are also given at different values of permeability ratios and different positions of the sublayer interface. It has been shown that the onset value of double-diffusive convection decreases with the growth of positive buoyancy ratio (heating of the system from below) but it, on the contrary, increases with that of the absolute negative buoyancy ratios (heating from above). It is possible due to the fact that in the first case both density gradients caused by the thermal and solutal differences are directed upwards so that a heavy cold solute accumulates near the upper boundary of the porous system and induces the most effective unstable density stratification. In the second case, the thermal and concentration density gradients are directed oppositely to each other, so the mixture motionless state stabilizes with the growth of temperature difference at the external boundaries of the layered medium. The clogging effect both under the isothermal and non-isothermal conditions can change the scale of convective roller flow abruptly: from the local convection to large-scale convection. This situation is typical for all of the heating directions (from below or from above).

The work was supported by the Russian Science Foundation (Grant No. 20-11-20125).
What determines estuary planform shape, size and channel-bar patterns?
Authors: Kleinhans Maarten , Weisscher Steven , Xie Danghan , Boechat Albernaz Marcio
Published: March 2022

Some estuaries gained their planform shape and size by sedimentation of mud flats and establishment of ‘coastal floodplains’ with saltmarsh or mangrove, while others are laterally confined by valley walls. For rivers, the channel dimensions and bar and bend shapes and sizes are related to upstream discharge, but for estuaries where most of the flow comes from the sea, there is no such fluid flux limit on size. This poses a riddle: what determines estuary planform shape, size and channel-bar patterns? Is there such a thing as an equilibrium or are multiple states possible under the same boundary conditions? A steady state  is a convenient concept in assessments of effects of human interference and changing boundary conditions.
We created sandy estuaries with mud and vegetation in numerical biogeomorphological modelling and in the Metronome tidal flume. The partial answers to the riddle include infilling by mud and flow-focussing by vegetation, but also the characteristics of the feeder river and tidal friction. For systems with plenty of sediment input, an `ideal' convergent estuary shape is one endmember equilibrium state. Here, the river, however small, mainly determines estuary size. Another equilibrium state is a system with mid-channel bars, where the collective multiple subtidal channels also develop a convergent shape as floodplains form. Likewise, unfilled estuaries with bay-head and flood deltas also tend to convergent shapes but filling can be arrested by lack of fine sediment, floodplain formation and vegetation settlement. Which of these quasi-steady states is reached depends in part on the system history of filling, wave energy, and (past) rate of sea-level rise.
Investigating 25 years of coupled climate modeling
Authors: Brunner Lukas , Lorenz Ruth , Fischer Erich M. , Knutti Reto
Published: March 2022

The Coupled Model Intercomparison Project (CMIP) is an effort to compare model simulations of the climate system and its changes. In the quarter of a century since CMIP1 models have increased considerably in complexity and improved in how well they are able to represent historical climate compared to observations. Other aspects, such as the projected changes we have to expect in a warming climate, have remained remarkably stable. Here we track the evolution of climate models based on their output and discuss it in the context of 25 years of model development. 

We draw on temperature and precipitation data from CMIP1 to CMIP6 and calculate consistent metrics of model performance, inter-dependence, and consistency across multiple generations of CMIP. We find clear progress in model performance that can be related to increased resolution among other things. Our results also show that the models’ development history can be tracked using their output fields with models sharing parts of their source code or common ancestors grouped together in a clustering approach.

The global distribution of projected temperature and precipitation change and its robustness across different models is also investigated. Despite the considerable increase in model complexity across the CMIP generations driven, for example, by the inclusion of additional model components and the increase in model resolutions by several orders of magnitude, the overall structure of simulated changes remains stable, illustrating the remarkable skill of early coupled models.
Which cloud microphysical processes are dispensable in a global aerosol climate model?
Authors: Proske Ulrike , Ferrachat Sylvaine , Lohmann Ulrike
Published: March 2022

Clouds are a major component of Earth's energy budget, influencing e.g. the radiative balance and precipitation formation. In turn, cloud properties are determined by the microphysical processes that occur within clouds, e.g. modifying their albedo.
Global climate models employ cloud microphysical schemes to parameterize these processes. The schemes have grown in detail and complexity, but it is doubtful whether this will help us to reduce uncertainty (Carslaw et al., 2018). In fact, cloud microphysics (CMP) and aerosol schemes have become so detailed that they are becoming difficult to constrain with observations (Reddington et al., 2017; Morrison et al., 2020) and to comprehend, while their results are more difficult to interpret. Simplification or removal of single processes within the CMP schemes might offer a remedy that reduces complexity and enhances interpretability. For such simplifications it is first necessary to determine which processes are non-influential so that less accurate descriptions could suffice.
Recently, Proske et al. (2021) applied global sensitivity analysis on an emulated perturbed parameter ensemble (PPE) of four CMP processes, perturbing their effectiveness in the global aerosol climate model ECHAM-HAM. They thereby investigated to which of the four processes the model is most sensitive. They found that accretion and self-collection of ice have a negligible influence while aggregation dominates the response to perturbations.
Here, we extend this analysis to the whole CMP scheme in ECHAM-HAM, creating a PPE of all processes, especially widening the scope to warm microphysics. With the analysis we characterize the scheme, uncover which processes drive the model response and suggest candidates for simplification to ultimately guide model development to a simplified representation of CMP.

Carslaw, Kenneth, Lindsay Lee, Leighton Regayre, and Jill Johnson. “Climate Models Are Uncertain, but We Can Do Something About It.” Eos 99, doi: 10.1029/2018EO093757, 2018.

Morrison, Hugh et al. “Confronting the Challenge of Modeling Cloud and Precipitation Microphysics.” Journal of Advances in Modeling Earth Systems 12, no. 8, doi: 10.1029/2019MS001689, 2020.

Proske, Ulrike et al. “Assessing the Potential for Simplification in Global Climate Model Cloud Microphysics.” Atmos. Chem. Phys. Discuss. [preprint], doi: 10.5194/acp-2021-801, in review, 2021.

Reddington, Carly et al. “The Global Aerosol Synthesis and Science Project (GASSP): Measurements and Modeling to Reduce Uncertainty.” Bulletin of the American Meteorological Society 98, no. 9, doi: 10.1175/BAMS-D-15-00317.1, 2017.
On the identification of hydrogeological reservoirs in a proglacial catchment and their future groundwater storage
Authors: Müller Tom , Schaefli Bettina , Lane Stuart N.
Published: March 2022

Rapid glacier retreat leads to the emergence of new rocky landscapes. The common assumption of the presence of bare bedrock underlying glaciers and the closely related assumption that glacier and snow melt manifest themselves essentially as surface runoff, is challenged by the rapid sediment accumulation and the formation of geomorphological landforms where water may be infiltrated and stored. Although some studies have provided rough estimates of groundwater storage and release in high elevation catchments, the actual reservoirs providing baseflow discharge are difficult to identify. While the combined effect of future glacier decline and earlier snowmelt are well recognized, it remains unclear how the rapid hydrogeomorphological transformations will modify the potential groundwater stores.

In this study we will provide results of a case study of a glaciated catchment in the Swiss Alps. Firstly, we will discuss, based on a simple modelling approach, the hydrological functioning of different landforms and show to which extend each hydrological unit is currently contributing to groundwater storage. We will then focus on a detailed assessment of the hydrological dynamics of an outwash plain using a 3D Modflow modelling approach. We will show how such a small fluvial aquifer is connected to other landforms and how it can maintain high storage during much longer time scales than other landforms due to strong river-groundwater interactions. Even though the current storage of the outwash plain is limited, we will discuss how glacier retreat may increase its relative contribution in the future. Finally, we will focus on the remaining unidentified storages in our field study and we will provide some geochemical analysis of their potential location and finally conclude with a summary of the hydrogeological functioning of a rapidly deglaciating proglacial catchment.
Ensemble modeling of radionuclide dispersion over the Arabian Peninsula from nuclear power plant accidents using FLEXPART
Authors: Nabavi Seyed Omid , Christoudias Theodoros , Fountoukis Christos , Al-Sulaiti Huda , Lelieveld Johannes
Published: March 2022

We intercompare simulations of the dispersion of aerosol and gaseous radionuclides (137Cs and 131I) driven by a four-member ensemble of (re-)analysis and forecast datasets to quantify statistical and systematic uncertainties. The Lagrangian particle dispersion model FLEXPART 10.4 and FLEXPART-WRF are driven by 6-hourly data from NCEP Global Forecast System (GFS) and Final Analysis (FNL), at spatial resolutions of 0.5 and 0.25 degrees. In addition, for running FLEXPART-WRF, the FNL and ECMWF Reanalysis v5 (ERA5) were first downscaled, to the finer resolutions of 10 km and 1 hour, using the Weather Research and Forecasting (WRF) model. A total of 365 experiments (each day of 2019) were conducted to produce hourly simulations at the spatial resolution of 10 km in 14 vertical levels through 96 hours after a fictitious nuclear power plant accident at Barakah, UAE, in an effort to study the potential risks to the population in the state of Qatar. The source term was scaled to the maximum estimates of the radioactive materials from the Fukushima accident in 2011 (0.042 kg of 131I and 7 kg of 137Cs), released within 24 hours after the accident. We intercompare radionuclide age spectra, cumulative deposition, and population exposure, seasonal variance, and investigate the degree of variability and correlation between ensemble members. Results show that the computational particles corresponded to dense 131I clouds enter Qatar more frequently within 10 to 20 hours after the accident. The cumulative distribution of simulated 137Cs depositions indicates that more than 80% of 137Cs depositions occurs within 75 hours after the accident, with a hotspot in the southeast of Qatar. GFS and ERA-5 show a high degree of correlation, whereas FNL is different. We also observe seasonal variation due to deposition and boundary layer development.
Characteristics of non-spherical manganese nodule from the East Siberian Sea
Authors: Cho Hyen Goo , Koo Hyo-Jin , Park Mu Seong , Seo Chung Man
Published: March 2022

Manganese nodules have been found in the shallow water depth of the Arctic Ocean as well as in the abyssal plains of the Pacific and Indian Oceans, but detailed study for them were rarely investigated. Manganese nodules, collected from the East Siberian Sea through the Arctic Expedition using Araon ice braking vessel, have a high potential for Mn mineral resources because they have high Mn content with high Mn/Fe ratio. This study investigated the external form, size and weight, internal texture for the non-spherical manganese nodule, which has about 7 % of total nodule from the East Siberian Sea. This study also researched the relative Mn-oxide mineral composition using the peak area ratio of X-ray diffraction pattern and their chemical composition. All data obtained from non-spherical nodules were compared with the spherical ones. Ellipsoidal, platy and irregular types are common among 5 groups of non-spherical manganese nodule based on the external form, and major axis and weight have positive relationship. All non-spherical manganese nodules have core mainly composed of mud sediments. The average Mn oxide mineral contents in nodules are birnessite, buserite and todorokite in descending order. Although mineral composition does not show any correlation with the external form, kind of core or internal structure, todorokite and buserite contents tend to increase and birnessite content decrease from the surface to the core in the nodule. Non-spherical manganese nodules have higher Mn content and Mn/Fe ratio than those from the shallow water depth of the Arctic Sea and even in the deep-sea of the Pacific and Indian Ocean. Almost all manganese nodules from this study are attributed to diagenetic process, because they are higher than 5 in Mn/Fe ratio.
Geoscience communication - Planning to make it publishable
Authors: Illingworth Sam , Hillier John , Welsh Katherine , Stiller-Reeve Mathew , Priestley Rebecca , Roop Heidi , Lanza Tiziana
Published: March 2022

If you are a geoscientist doing work to achieve impact outside academia or engaging different audiences with the geosciences, are you planning to make this publishable? If so, then plan. Such investigations into how people (academics, practitioners, other publics) respond to geoscience can use pragmatic, simple research methodologies accessible to the non-specialist, or be more complex. To employ a medical analogy, first aid is useful and the best option in some scenarios but calling a medic (i.e. a collaborator with experience of geoscience communication or relevant research methods) provides the contextual knowledge to identify a condition and opens up a diverse, more powerful range of treatment options. Here, we expand upon the brief advice in the first editorial of Geoscience Communication (Illingworth et al., 2018), illustrating what constitutes robust and publishable work in this context, elucidating its key elements. Our aim is to help geoscience communicators plan a route to publication, and to illustrate how good engagement work that is already being done might be developed into publishable research. 

Reference

Illingworth, S., Stewart, I., Tennant, J., and von Elverfeldt, K.: Editorial: Geoscience Communication – Building bridges, not walls, Geosci. Commun., 1, 1–7, https://doi.org/10.5194/gc-1-1-2018, 2018.

 

 
Causal evaluation of Arctic-midlatitude processes in CMIP6 model simulations
Authors: Galytska Evgenia , Weigel Katja , Runge Jakob , Handorf Dörthe , Jaiser Ralf , Köhler Raphael , Eyring Veronika
Published: March 2022

The impact of various mechanisms that link Arctic and midlatitude processes occurring in conditions of amplified Arctic warming is still under debate. Observational and model studies lead to divergent conclusions. This has spurred a number of research activities aiming to apply innovative approaches to improve process understanding. Therefore, to identify robust relationships in the complex Arctic-midlatitude linkages, we apply a novel method that goes beyond simple correlation analysis, known as Causal Networks or Causal Discovery. This allows us to analyze, characterize, and quantify key processes that contribute to the linkage between the Arctic and midlatitudes on a monthly timescale. In particular, we focus on the causal connections among key actors, such as Arctic near-surface temperature and sea ice, near-surface pressure over central Asia, vertical wave propagation, and its further link to the stratospheric polar vortex. Additionally, we analyze the contribution of remote large-scale processes, such as El Niño–Southern Oscillation, Quasi Biennial Oscillation, and North Atlantic Oscillation. In this study, we summarize the comparisons between historical Coupled Model Intercomparison Project Phase 6 (CMIP6) model runs and observational data. On the one hand, our analysis shows that the majority of historical CMIP6 models agree with observations on the significant causal connection between near-surface air temperature and sea ice extent in the Arctic region. These model results also capture the tropospheric-stratospheric coupling and downward impact from the stratosphere to the troposphere shown by observations. On the other hand, we also focus on discrepancies between model simulations and observations and provide possible explanations of investigated differences. These outcomes provide the basis to investigate changes in the links between Arctic and midlatitudes for simulations with various forcings and future scenarios.
Climatology and Long-Term Trends in the Stratospheric Temperature and Wind Using ERA5
Authors: Zajíček Radek , Kozubek Michal , Laštovička Jan
Published: March 2022

This study analyses long-term trends in temperature and wind climatology based on ERA5 data. We study climatology and trends separately for every decade from 1980 to 2020 and their changes during this period for winter (DJF for the NH and JJA for the SH) for 40–90°N/S . This study is focused on the pressure levels between 100–1 hPa, which essentially covers the whole stratosphere. We also analyze the impact of the sudden stratospheric warmings (SSW), North Atlantic Oscillation (NAO), El Nino Southern Oscillation (ENSO) and Quasi-biennial oscillation (QBO). This helps us to find details of climatology and trend behavior in the stratosphere in connection to these phenomena. ERA5 is one of the newest reanalysis, which is widely used for the middle atmosphere. We identify the largest differences which occur between 1990–2000 and 2000–2010 in both temperature climatology and trends. We suggest that these differences could relate to the different occurrence frequency of SSWs in 1990–2000 versus 2000–2010.
Comparison of the Revised and Modified USLE models for prediction of sediment yield from grazing land in Central Queensland, Australia
Authors: Tiwari Jagriti , Yu Bofu , Silburn D Mark , Bartley Rebecca , Thornton Craig M , Owens Jo , Brooks Andrew
Published: March 2022

One of the major issues of the grazing land ecosystem is high sediment yield linked to extensive land clearing and conversion of native vegetation into grazing. It is essential to model hillslope sedimentation for improved prediction of sediment yield in grazed catchments. This study evaluated the performance of Revised Universal Soil Loss Equation (RUSLE) and Modified Universal Soil Loss Equation (MUSLE) models in predicting sediment yield from grazed catchments and analyzed the effects of runoff, peak runoff rate and the RUSLE/MUSLE factor on annual sediment yield. Springvale, Brigalow, and Weany Creek catchments from Fitzroy and Burdekin Basins in Queensland, Australia, were selected as study areas. The MUSLE models performed better as compared to the RUSLE model for all three catchments. Compared to the RUSLE model, the MUSLE1 model with factors runoff and peak runoff rate was able to predict sediment yield for Weany creek and Brigalow catchment and the MUSLE2 with factors rainfall-runoff erosivity (EI30), runoff, and peak runoff rate performed well for Springvale and Brigalow catchment. The study found rainfall and runoff factors in Springvale and Brigalow catchments, and runoff factor and peak runoff rate in Weany catchments contributed to the variation of sediment yield. The estimated soil erodibility factor (K) was found 14%, 24%, and 60% higher for Springvale, Brigalow, and Weany Creek catchments, respectively, compared to K-factor from the Australian Soil Resource Information System (ASRIS). This study recommends using the MUSLE model to improve hillslope sediment yield prediction in grazing lands in Central Queensland.
What flow conditions are conducive to banner cloud formation at Mt. Matterhorn?
Authors: Thomas Marius Levin , Wirth Volkmar , Piotrowski Zbigniew
Published: March 2022

Banner clouds are clouds that appear to be attached on the leeward side of a steep mountain or ridge on otherwise cloud-free days. The current work considers fundamental questions associated with the formation of this type of clouds using large-eddy simulations. Previous work was based on an idalized model configuration with  pyramid-shaped orography; there, it was shown that the shear of the oncoming flow plays a key role for the geometry of the lee-side vortex and, hence, for the shape of the banner cloud. 

In the current work, the scope is extended from an idealized pyramid to the realistic orography of Mt Matterhorn. The simulations show that the wind shear of the oncoming flow is less essential than before, because the underlying rough orography creates "its own" flow profile by the time the flow reaches the windward side of the mountain. By contrast, the wind speed turns out to be quite relevant, because large windspeed is associated with strong turbulence, turbulence reduces stratification, and reduced stratification helps to form the lee vortex. However, at the same time, the flow field for realistic Matterhorn orography makes it much harder to identify a coherent lee vortex to be associated with the banner cloud. 
 First results from comparison ERA5 and Aeolus measurements: Lidar measurements to Identify Streamers and analyze Atmospheric waves (LISA) (Aeolus+Innovation)
Authors: Kozubek Michal , Lastovicka Jan , Chum Jaroslav , Sindelarova Tereza , Podolska Katerina , Kuechelbacher Lisa , Wuest Sabine , Bittner Michael
Published: March 2022

For a better understanding of atmospheric dynamics, it is very important to know the general condition (dynamics and chemistry) in the atmosphere. Aeolus wind measurements provide wind measurements from satellite instrument. ERA 5 can produce very detailed information about dynamics without gaps in time series in high resolution (0.25°). Planetary waves (PWs) are global scale waves, which are well-known as main drivers of the large-scale weather patterns in mid-latitudes on time scales from several days up to weeks in the troposphere. When PWs break, they often cut pressure cells off the jet stream. A specific example are so-called streamer events, which occur predominantly in the mid- and high-latitudes of the lower stratosphere. Streamers are characterized by ozone-poor airmasses occuring mainly in the Northern Atlantic / European section and leading to various consequences due to a strong increase of UV radiation. We compare ERA5 reanalysis with Aeolus measurements. This comparison can bring us an answer if we can use ERA5 instead of Aeolus measurements in case of time gaps. We also use homogeneity test for ERA5 time series. Moreover, we also analyze characteristics of gravity waves (GW) in the ionosphere using continuous Doppler sounding and in the troposphere using large aperture array of microbarometers. Similarly, ground based infrasound monitoring is performed. We investigate, if there are any changes of GW or infrasound characteristics related to stratospheric processes, e.g., streamer events.
Performance testing of optical flow time series analyses based on a fast, high–alpine landslide
Authors: Hermle Doris , Gaeta Michele , Krautblatter Michael , Mazzanti Paolo , Keuschnig Markus
Published: March 2022

Accurate remote analyses of high–alpine landslides are a key requirement for future alpine safety. In critical stages of alpine landslides, UAV (unmanned aerial vehicle) data can be employed, using image registration techniques to derive ground motion with high temporal and spatial resolution. Nevertheless, the classical area–based algorithms, dynamic surface alterations, and limited velocity range restrict detection, which results in noise from decorrelation, preventing their application to fast and complex landslides.

Here for the first time to our knowledge, we apply optical flow time series to analyse one of the fastest and most critical debris flow source zones in Austria. The benchmark site Sattelkar (2’130-2’730 m asl), a steep, high–alpine cirque in Austria, is highly sensitive to rainfall and melt–water events, which led to a 70.000 m³ debris slide event in July 2014. We use a UAV data set (0.16 m) collected over three years (five acquisitions, 2018-2020). Our novel approach is to employ optical flow, which, along with phase correlation, is incorporated into the software IRIS. To test the performance, we compared the two algorithms by applying them to image stacks to calculate time–series displacement curves and ground motion maps. These maps enable us to precisely identify compartments of the complex landslide body and reveal different displacement patterns, with displacement curves reflecting an increased acceleration. Traceable boulders in the UAS orthophotos independently validate the methodology applied. We demonstrate that UAV optical flow time series analysis generates a better signal extraction and a wider observable velocity range, highlighting how it can be applied to a fast, high–alpine landslide.
Effects of seasonal variations in vegetation cover and precipitation rates on catchment-scale erosion rates
Authors: Sharma Hemanti , Ehlers Todd A. , Glotzbach Christoph
Published: March 2022

Precipitation in wet seasons is the main driver of fluvial erosion and accounts for a significant contribution to annual erosion rates. However, wet seasons also encounter an increase in vegetation cover, which helps to resist erosion. This study quantifies the implications of present-day seasonal variations in rainfall and spatially variable vegetation cover on erosion rates over distinct climate-vegetation settings. We do this using the Landlab-SPACE landscape evolution model modified to account for weathering, rainfall-infiltration-runoff, and the effects of vegetation cover on hillslope and fluvial processes. The input parameters also include present-day SRTM DEM (90m) for the initial condition, MODIS NDVI, and weather station observations of precipitation (between 2000 – 2019). The soil properties (input parameters) and dynamically evolving soil depths were considered to estimate soil-water infiltration using the Green-Ampt method. Simulations were tuned to four selected catchments in the Chilean Coastal Cordillera (~26 °S – ~38 °S) which contains a steep climate (from arid to temperate humid) and ecological gradient with similar granodiorite lithology and tectonic forcings. The size (and mean slopes) of the catchments range from 64 (8°) – 142.5 km2 (23°). These catchments are not in steady-state with a background uplift rate of 0.05 mm yr-1. We designed multiple sets of simulations to explore the sensitivity of catchment scale erosion rates to seasonal variations in precipitation and/or vegetation cover. The simulations were conducted for 1,000 years (20 years of vegetation and precipitation observations repeated 50 times) with a time-step of 1 season (3 months). After detrending the results for long-term transient changes, the last 20 years were analyzed. Results indicate that when vegetation cover is varied but precipitation is held constant then the amplitude of change in erosion rates is very low (e.g. 17% in the humid setting). Whereas, in simulations with variable precipitation change and constant vegetation cover, and coupled variations in both precipitation and vegetation cover, the amplitude of change in erosion rates is higher and in a similar range (e.g., 95% in the humid setting). The results during wet seasons also indicate that erosion in the semi-arid region is ~2 times and ~4 times more sensitive than mediterranean and humid regions respectively. However, minimal erosion is observed in the arid setting, due to low precipitation subjected to soil infiltration which leads to lower runoff than the erosion threshold. Overall, we found that at a seasonal scale, erosion rates are significantly influenced by precipitation variations and base vegetation cover (moderately by seasonal variations). Secondly, the vulnerability of erosion rates to weather seasonality increases from humid to semi-arid regions.
The impact of submesoscale fronts on turbulent air-sea heat fluxes in the Southern Ocean: Results from the first Saildrone circumnavigation of Antarctica
Authors: Rosenthal Hanna , Biddle Louise C. , Swart Sebastiaan , Gille Sarah T. , Mazloff Matthew R. , du Plessis Marcel
Published: March 2022

The Southern Ocean is fundamental for our climate, accounting for 75% of the total oceanic heat uptake and absorbing 93% of excess heat arising from global warming. However, direct observations of air-sea heat fluxes are still scarce, particularly at small spatial and temporal scales. This study investigates the effect of fine-scale frontal activity (0.1 km–10 km) and sampling bias on measured turbulent heat fluxes in the Southern Ocean using high-resolution hydrographic and meteorological data collected by three autonomous surface vehicles (Saildrones) during their 2019 circumnavigation of Antarctica. We show that the uncertainty in observed air-sea heat fluxes increases with reduced sampling frequency. To have a  90% chance of capturing the mean turbulent heat flux within ±1 Wm2, the required sampling resolution is less than 30 km in summer and less than 10 km in winter. Surface temperature-driven density fronts were found to be numerous throughout the in situ datasets and ranged in length-scales from sub-kilometer to mesoscale (order of 0.1 km–100 km). The magnitude and variability of the turbulent heat flux gradient over these fronts tends to decrease with increasing frontal length, suggesting a strong coupling between heat fluxes and front size, thereby underscoring the need to capture fine-scale oceanographic features to better resolve air-sea fluxes of heat.
Global governance of ocean-based negative emission technologies. Exploring gaps, challenges, and opportunities
Authors: Neumann Barbara , Röschel Lina
Published: March 2022

To achieve the ambitious but necessary climate targets set by the Paris Agreement, the IPCC model pathways for limiting global warming to 1.5°C compared to pre-industrial levels make apparent the need for safeguarding and enhancing the natural global carbon sink – including via carbon dioxide removal (CDR). A range of ocean-based CDR approaches, also termed “negative emissions technologies” (NETs), has been proposed to make use of the ocean’s potential to take up carbon dioxide from the atmosphere and store it in water, biomass, and sediments. The governance framework in place to regulate CDR in the ocean, at this time, is limited to the direct and articulate regulation of ocean fertilization. Meanwhile, other NETs such as ocean alkalinity enhancement and artificial upwelling emerge, but a comprehensive and foresight-oriented regulation for the testing or even deploying at larger scale is missing. Specifically, there is large uncertainty on unintended (positive and negative) effects of these technologies on the condition of the ocean, in addition to enhanced carbon uptake and storage, and how these may impede on or support other global sustainability goals. The deployment of NETs in the ocean poses additional governance complexities relating to unknowns, uncertainties, and transboundary issues. In a study that is part of the EU H2020-project OceanNETs, we explore to what extent the current global governance framework directly or indirectly regulates emerging ocean-based NETs and reflect on the particularities and requirements for their comprehensive governance. The analysis considers the gaps, challenges, needs, and opportunities for comprehensive governance of ocean-based NETs. 
Gyrotactic plankton cells in turbulence: the effects of motility, shape, fluid acceleration and inertia
Authors: Climent Eric , Qiu Jingran , Cui Zhiwen , Zhao Lihao
Published: March 2022

A detailed understanding of the physical mechanisms driving gyrotactic species to migrate vertically towards the surface allows better quantification of biogeochemical fluxes across the ocean. We focus on marine phytoplankton cells that are motile under gyrotactic forcing. Some species spontaneously swim in the direction opposite to gravity [1]. Gyrotaxis is originating either from morphological aspects (elongated shape, density heterogeneity) or the coupled effect of swimming and settling which results in an inertial torque. Indeed, fluid inertial torque may have a potential impact on the gyrotaxis for elongated planktonic swimmers, especially for those forming long chains and thus having large swimming and settling speeds
Based on numerical simulations of hundreds of thousands of micro-organisms swimming in homogeneous isotropic turbulence, we will comment on the different sources of gyrotactic induced spatial clustering [2, 3] and vertical migration [4]. Some specific configurations lead to the accumulation of elongated plankton cells in upwelling flow regions enhancing their ability to move across turbulence through the water column.  

[1] Kessler J.O. (1985), Nature - 313, 218–220.
[2] Durham W. M., et al. (2013) Nat. Commun. - 4, 2148.
[3] De Lillo F., et al. (2014) Phys. Rev. Lett. – 112, 044502
[4] Lovecchio S., et al. (2019) Sci. Adv. - 5: eaaw7879