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Climate of the Past

Plateaus and jumps in the atmospheric radiocarbon record – potential origin and value as global age markers for glacial-to-deglacial paleoceanography, a synthesis

The dating technique of ¹⁴ C plateau tuning uses U/Th-based model ages, refinements of the Lake Suigetsu age scale, and the link of surface ocean carbon to the globally mixed atmosphere as basis of age correlation. Our synthesis employs data of 20 sediment cores from the global ocean and offers a coherent picture of global ocean circulation evolving over glacial-to-deglacial times on semi-millennial scales to be compared with climate records stored in marine sediments, ice cores, and speleothems.

Atmospheric Chemistry and Physics

Long-term deposition and condensation ice-nucleatingparticle measurements from four stations across the globe

Long-term ice-nucleating particle (INP) data are presented from four semi-pristine sites located in the Amazon, the Caribbean, Germany and the Arctic. Average INP concentrations did not differ by orders of magnitude between the sites. For all sites short-term variability dominated the time series, which lacked clear trends and seasonalities. Common drivers to explain the INP levels and their variations could not be identified, illustrating the complex nature of heterogeneous ice nucleation.

Earth System Dynamics

Emergent constraints on equilibrium climate sensitivity in CMIP5: do they hold for CMIP6?

As an important measure of climate change, the Equilibrium Climate Sensitivity (ECS) describes the change in surface temperature after a doubling of the atmospheric CO ₂ concentration. Climate models from the Coupled Model Intercomparison Project (CMIP) show a wide range in ECS. Emergent constraints are a technique to reduce uncertainties in ECS with observational data. Emergent constraints developed with data from CMIP phase 5 show reduced skill and higher ECS ranges when applied to CMIP6 data.

The Cryosphere

Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica

The West Antarctic Ice Sheet has long been considered geometrically prone to collapse, and Thwaites Glacier, the largest glacier in the Amundsen Sea, is likely in the early stages of disintegration. Using observations of Thwaites Glacier velocity and elevation change, we show that the transport of ~2 km ³ of water beneath Thwaites Glacier has only a small and transient effect on glacier speed relative to ongoing thinning driven by ocean melt.

Natural Hazards and Earth System Sciences

Downsizing parameter ensembles for simulations of rare floods

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-20-3521-2020
15 January 2021

This work proposes methods for reducing the computational requirements of hydrological simulations for the estimation of very rare floods that occur on average less than once in 1000 years. These methods enable the analysis of long streamflow time series (here for example 10 000 years) at low computational costs and with modelling uncertainty. They are to be used within continuous simulation frameworks with long input time series and are readily transferable to similar simulation tasks.

Earth System Dynamics

Biases in the albedo sensitivity to deforestation in CMIP5 models and their impacts on the associated historical radiative forcing

Trees are darker than crops or grasses; hence, they absorb more solar radiation. Therefore, land cover changes modify the fraction of solar radiation reflected by the land surface (its albedo), with consequences for the climate. We apply a new statistical method to simulations conducted with 15 recent climate models and find that albedo variations due to land cover changes since 1860 have led to a decrease in the net amount of energy entering the atmosphere by −0.09 W m ² on average.

Atmospheric Measurement Techniques

Quantifying CO2 emissions of a city with the Copernicus Anthropogenic CO2 Monitoring satellite mission

The European CO2M mission is a proposed constellation of CO ₂ imaging satellites expected to monitor CO ₂ emissions of large cities. Using synthetic observations, we show that a constellation of two or more satellites should be able to quantify Berlin’s annual emissions with 10–20 % accuracy, even when considering atmospheric transport model errors. We therefore expect that CO2M will make an important contribution to the monitoring and verification of CO ₂ emissions from cities worldwide.

Natural Hazards and Earth System Sciences

New global characterisation of landslide exposure

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-20-3413-2020
12 January 2021

Landslides cause thousands of fatalities and cost billions of dollars of damage worldwide every year, but different inventories of landslide events can have widely diverging completeness. This can lead to spatial biases in our understanding of the impacts. Here we use a globally homogeneous model of landslide hazard and exposure to provide consistent estimates of where landslides are most likely to cause damage to people, roads and other critical infrastructure at 1 km resolution.

Atmospheric Chemistry and Physics

Tropical Pacific climate variability under solar geoengineering: impacts onENSO extremes

Solar geoengineering has been introduced to mitigate human-caused global warming by reflecting sunlight back into space. This research investigates the impact of solar geoengineering on the tropical Pacific climate. We find that solar geoengineering can compensate some of the greenhouse-induced changes in the tropical Pacific but not all. In particular, solar geoengineering will result in significant changes in rainfall, sea surface temperatures, and increased frequency of extreme ENSO events.

Climate of the Past

Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study

We tested the applicability of the organic biomarker IPSO ₂₅ for sea ice reconstructions in the industrial era at the western Antarctic Peninsula. We successfully evaluated our data with satellite sea ice observations. The comparison with marine and ice core records revealed that sea ice interpretations must consider climatic and sea ice dynamics. Sea ice biomarker production is mainly influenced by the Southern Annular Mode, while the El Niño–Southern Oscillation seems to have a minor impact.

Atmospheric Chemistry and Physics

Optical characterization of pure pollen types using a multi-wavelength Raman polarization lidar

Measurements of the multi-wavelength Raman polarization lidar Polly ^XT have been combined with measurements of pollen type and concentration using a traditional pollen sampler at a rural forest site in Kuopio, Finland. The depolarization ratio was enhanced when there were pollen grains in the atmosphere, illustrating the potential of lidar to track pollen grains in the atmosphere. The depolarization ratio of pure pollen particles was assessed for birch and pine pollen using a novel algorithm.

Atmospheric Measurement Techniques

Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment

To study the feasibility of a fluorescence lidar for aerosol characterization, the fluorescence channel is added to the multiwavelength Mie-Raman lidar of Lille University. A part of the fluorescence spectrum is selected by the interference filter of 44 nm bandwidth centered at 466 nm. Such an approach has demonstrated high sensitivity, allowing fluorescence signals from weak aerosol layers to be detected. The technique can also be used for monitoring the aerosol inside the cloud layers.

Atmospheric Chemistry and Physics

The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – theoretical framework

A novel lidar method to study cloud microphysical properties (of liquid water clouds) and to study aerosol–cloud interaction (ACI) is developed and presented in this paper. In Part 1, the theoretical framework including an error analysis is given together with an overview of the aerosol information that the same lidar system can obtain. The ACI concept based on aerosol and cloud information is also explained. Applications of the proposed approach to lidar measurements are presented in Part 2.

Earth Surface Dynamics

Evolution of events before and after the 17 June 2017 rock avalanche at Karrat Fjord, West Greenland – a multidisciplinary approach to detecting andlocating unstable rock slopes in a remote Arctic area

The 17 June 2017 Karrat landslide in Greenland caused a tsunami that killed four people. We apply a multidisciplinary workflow to reconstruct a timeline of events and find that three historic landslides occurred in 2009, 2016, and 2017. We also find evidence of much older periods of landslide activity. Three newly discovered active slopes might pose a future hazard. We speculate that the trigger for the recent events is melting permafrost due to a warming climate.

SOIL

Iron and aluminum association with microbially processed organic matter viameso-density aggregate formation across soils: organo-metallic gluehypothesis

SOIL
DOI 10.5194/soil-6-597-2020
1 January 2021

Global significance of metals (extractable Fe and Al phases) to control organic matter (OM) in recognized. Next key questions include the identification of their localization and mechanism behind OM–metal relationships. Across 23 soils of contrasting mineralogy, Fe and Al phases were mainly associated with microbially processed OM as meso-density microaggregates. OM- and metal-rich nanocomposites with a narrow OM : metal ratio likely acted as binding agents. A new conceptual model was proposed.

The Cryosphere

The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness

Our current understanding of Antarctic ice cover is largely informed by ice extent measurements from passive microwave sensors. These records, while useful, provide a limited picture of how the ice is responding to climate change. In this paper, we combine measurements from ICESat-2 and CryoSat-2 missions to assess snow depth and ice thickness of the Antarctic ice cover over an 8-month period (April through November 2019). The potential impact of salinity in the snow layer is discussed.

The Cryosphere

The catastrophic thermokarst lake drainage events of 2018 in northwesternAlaska: fast-forward into the future

In summer 2018, northwestern Alaska was affected by widespread lake drainage which strongly exceeded previous observations. We analyzed the spatial and temporal patterns with remote sensing observations, weather data and lake-ice simulations. The preceding fall and winter season was the second warmest and wettest on record, causing the destabilization of permafrost and elevated water levels which likely led to widespread and rapid lake drainage during or right after ice breaku

Geoscience Communication

Focus on glaciers: a geo-photo exposition of vanishing beauty

We organized an exhibition on the climate crisis using high-quality images shot by scientists, who are amateur photographers, during their campaigns in glacier regions. Working-age people, attracted by the gorgeous images, received the message that such beauty is in danger of vanishing. Twice, the visitors could talk directly with the experts to discuss geoscience, photography, and aesthetic choices and, of course, climate change, a problem that each of us has to play a part in to solve.

Biogeosciences

Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model

We developed a 1 km satellite-data-driven permafrost carbon model to evaluate soil respiration sensitivity to recent snow cover changes in Alaska. Results show earlier snowmelt enhances growing-season soil respiration and reduces annual carbon uptake, while early cold-season soil respiration is linked to the number of snow-free days after the land surface freezes. Our results also show nonnegligible influences of subgrid variability in surface conditions on model-simulated CO ₂ seasonal cycles.

Natural Hazards and Earth System Sciences

A systematic exploration of satellite radar coherence methods for rapid landslide detection

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-20-3197-2020
25 December 2020

Satellite radar could provide information on landslide locations within days of an earthquake or rainfall event anywhere on Earth, but until now there has been a lack of systematic testing of possible radar methods, and most methods have been demonstrated using a single case study event and data from a single satellite sensor. Here we test five methods on four events, demonstrating their wide applicability and making recommendations on when different methods should be applied in the future.

Hydrology and Earth System Sciences

New flood frequency estimates for the largest river in Norway based on the combination of short and long time series

We combine systematic, historical, and paleo information to obtain flood information from the last 10 300 years for the Glomma River in Norway. We identify periods with increased flood activity (4000–2000 years ago and the recent 1000 years) that correspond broadly to periods with low summer temperatures and glacier growth. The design floods in Glomma were more than 20 % higher during the 18th century than today. We suggest that trends in flood variability are linked to snow in late spring.

Solid Earth

Tectonic exhumation of the Central Alps recorded by detrital zircon in theMolasse Basin, Switzerland

Solid Earth
DOI 10.5194/se-11-2197-2020
23 December 2020

We present new U–Pb age data to provide insights into the source of sediment for the Molasse Sedimentary Basin in Switzerland. The paper aims to help shed light on the processes that built the Central Alpine Mountains between ~35 and ~15 Ma. A primary conclusion drawn from the results is that at ~21 Ma there was a significant change in the sediment sources for the basin. We feel this change indicates major tectonic changes within the Central Alps.

Climate of the Past

Evaluation of Arctic warming in mid-Pliocene climate simulations

The simulations for the past climate can inform us about the performance of climate models in different climate scenarios. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), when the CO ₂ level was comparable to today. The results highlight the importance of slow feedbacks in the model simulations and imply that we must be careful when using simulations of the mPWP as an analogue for future climate change.

Atmospheric Chemistry and Physics

Sensitivity of the Southern Hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistry

Ozone depletion over Antarctica was shown to influence the tropospheric jet in the Southern Hemisphere. We investigate the atmospheric response to ozone depletion comparing climate model ensembles with interactive and prescribed ozone fields. We show that allowing feedbacks between ozone chemistry and model physics as well as including asymmetries in ozone leads to a strengthened ozone depletion signature in the stratosphere but does not significantly affect the tropospheric jet position.

The Cryosphere

Distinguishing the impacts of ozone and ozone-depleting substanceson the recent increase in Antarctic surface mass balance

The increase in Antarctic surface mass balance (SMB, precipitation vs. evaporation/sublimation) is projected to mitigate sea-level rise. Here we show that nearly half of this increase over the 20th century is attributed to stratospheric ozone depletion and ozone-depleting substance (ODS) emissions. Our results suggest that the phaseout of ODS by the Montreal Protocol, and the recovery of stratospheric ozone, will act to decrease the SMB over the 21st century and the mitigation of sea-level rise.

Geoscience Communication

Earth Girl Volcano: characterizing and conveying volcanic hazard complexity in an interactive casual game of disaster preparedness and response

Earth Girl Volcano is a casual strategy interactive game about saving communities at risk of volcanic hazards. The easy-to-play game features a friendly animated visual style and an engaging simulation of volcanic events. The game was designed by a multidisciplinary team to appeal to mainstream non-technical audiences, and it was inspired by the experiences of disaster survivors and civil defense teams. Players can learn through gameplay about disaster preparedness and response.

Geoscientific Instrumentation, Methods and Data Systems

The baseline wander correction based on the improved ensemble empirical mode decomposition (EEMD) algorithm for groundedelectrical source airborne transient electromagnetic signals

Geoscientific Instrumentation, Methods and Data Systems
DOI 10.5194/gi-9-443-2020
16 December 2020

The baseline wander has special characteristics, such as being low frequency, large amplitude, non-periodic, and non-stationary. It is caused by the receiving coil motion and always exists in the process of data acquisition. The proposed method can be used to solve similar problems. This paper has the following highlights: (1) the method can be used to process non-periodic and non-stationary signals; (2) the method is adaptive to satisfy the stopping criterion based on the measured signal.

Climate of the Past

Millennial-scale atmospheric CO2 variations during the Marine Isotope Stage 6 period (190–135 ka)

We reconstruct atmospheric CO ₂ from the EPICA Dome C ice core during Marine Isotope Stage 6 (185–135 ka) to understand carbon mechanisms under the different boundary conditions of the climate system. The amplitude of CO ₂ is highly determined by the Northern Hemisphere stadial duration. Carbon dioxide maxima show different lags with respect to the corresponding abrupt CH ₄ jumps, the latter reflecting rapid warming in the Northern Hemisphere.

Earth System Dynamics

Reduced global warming from CMIP6 projections when weighting models by performance and independence

In this study, we weight climate models by their performance with respect to simulating aspects of historical climate and their degree of interdependence. Our method is found to increase projection skill and to correct for structurally similar models. The weighted end-of-century mean warming (2081–2100 relative to 1995–2014) is 3.7 °C with a likely (66 %) range of 3.1 to 4.6 °C for the strong climate change scenario SSP5-8.5; this is a reduction of 0.4 °C compared with the unweighted mean.

Geoscientific Model Development

European daily precipitation according to EURO-CORDEX regionalclimate models (RCMs) andhigh-resolution globalclimate models (GCMs) from the High-Resolution Model Intercomparison Project (HighResMIP)

Now that global climate models (GCMs) can run at similar resolutions to regional climate models (RCMs), one may wonder whether GCMs and RCMs provide similar regional climate information. We perform an evaluation for daily precipitation distribution in PRIMAVERA GCMs (25–50 km resolution) and CORDEX RCMs (12–50 km resolution) over Europe. We show that PRIMAVERA and CORDEX simulate similar distributions. Considering both datasets at such a resolution results in large benefits for impact studies.

Atmospheric Measurement Techniques

Validation of Aeolus wind products above the Atlantic Ocean

A first validation for the European satellite Aeolus is presented. Aeolus is the first satellite that can actively measure horizontal wind profiles from space.
Radiosonde launches on board the German research vessel Polarstern have been utilized to validate Aeolus observations over the Atlantic Ocean, a region where almost no other reference measurements are available. It is shown that Aeolus is able to measure accurately atmospheric winds and thus may significantly improve weather forecasts.

The Cryosphere

Review article: Geothermal heat flow in Antarctica: current and future directions

The Antarctic ice sheet is the largest source for sea level rise. However, one key control on ice sheet flow remains poorly constrained: the effect of heat from the rocks beneath the ice sheet (known as geothermal heat flow). Although this may not seem like a lot of heat, beneath thick, slow ice this heat can control how well the ice flows and can lead to melting of the ice sheet. We discuss the methods used to estimate this heat, compile existing data, and recommend future research.

SOIL

Soil: the great connector of our lives now and beyond COVID-19

SOIL
DOI 10.5194/soil-6-541-2020
8 December 2020

Humanity depends on the existence of healthy soils, both for the production of food and for ensuring a healthy, biodiverse environment. In the face of global crises like the COVID-19 pandemic, a sustainable soil management strategy is essential to ensure food security based on more diverse, locally oriented, and resilient food production systems through improving access to land, sound land use planning, sustainable soil management, enhanced research, and investment in education and extension.

Hydrology and Earth System Sciences

The pulse of a montane ecosystem: coupling between daily cycles in solar flux, snowmelt, transpiration, groundwater, and streamflow at Sagehen Creek and Independence Creek, Sierra Nevada, USA

Streams and groundwaters often show daily cycles in response to snowmelt and evapotranspiration. These typically have a roughly 6 h time lag, which is often interpreted as a travel-time lag. Here we show that it is instead primarily a phase lag that arises because aquifers integrate their inputs over time. We further show how these cycles shift seasonally, mirroring the springtime retreat of snow cover to higher elevations and the seasonal advance and retreat of photosynthetic activity.

Atmospheric Chemistry and Physics

Long-term historical trends in air pollutant emissions in Asia: Regional Emission inventory in ASia (REAS) version 3

A long historical emission inventory of major air pollutants in Asia during 1950–2015 was developed as Regional Emission inventory in ASia version 3 (REASv3). Trends of emissions and changes in source contributions in countries and regions in Asia during these 6 decades were analyzed. REASv3 provides monthly gridded data with 0.25° by 0.25° resolution for major source categories as well as table of emissions by countries and sub-regions for major sectors and fuel types.

Climate of the Past

The Pliocene Model Intercomparison Project Phase 2: large-scale climate features and climate sensitivity

The large-scale features of middle Pliocene climate from the 16 models of PlioMIP Phase 2 are presented. The PlioMIP2 ensemble average was ~ 3.2 °C warmer and experienced ~ 7 % more precipitation than the pre-industrial era, although there are large regional variations. PlioMIP2 broadly agrees with a new proxy dataset of Pliocene sea surface temperatures. Combining PlioMIP2 and proxy data suggests that a doubling of atmospheric CO ₂ would increase globally averaged temperature by 2.6–4.8 °C.

Atmospheric Chemistry and Physics

Vertical variability of the properties of highly aged biomass burning aerosol transported over the southeast Atlantic during CLARIFY-2017

Airborne measurements of highly aged biomass burning aerosols (BBAs) over the remote southeast Atlantic provide unique aerosol parameters for climate models. Our observations demonstrate the persistence of strongly absorbing BBAs across wide regions of the South Atlantic. We also found significant vertical variation in the single-scattering albedo of these BBAs, as a function of relative chemical composition and size. Aerosol properties in the marine BL are suggested to be separated from the FT.

Atmospheric Chemistry and Physics

A microphysics guide to cirrus – Part 2:Climatologies of clouds and humidity from observations

To improve the representations of cirrus clouds in climate predictions, extended knowledge of their properties and geographical distribution is required. This study presents extensive airborne in situ and satellite remote sensing climatologies of cirrus and humidity, which serve as a guide to cirrus clouds. Further, exemplary radiative characteristics of cirrus types and also in situ observations of tropical tropopause layer cirrus and humidity in the Asian monsoon anticyclone are shown.

Atmospheric Chemistry and Physics

The Aarhus Chamber Campaign on Highly Oxygenated Organic Molecules andAerosols (ACCHA): particle formation, organic acids, and dimer esters fromα-pinene ozonolysis at different temperatures

Atmospheric particles are important in relation to human health and the global climate. As the global temperature changes, so may the atmospheric chemistry controlling the formation of particles from reactions of naturally emitted volatile organic compounds (VOCs). In the current work, we show how temperatures influence the formation and chemical composition of atmospheric particles from α-pinene: a biogenic VOC largely emitted in high-latitude environments such as the boreal forests.

Atmospheric Chemistry and Physics

Large contribution of organics to condensational growth and formation of cloud condensation nuclei (CCN) in the remote marine boundary layer

Condensational growth of Aitken-mode particles is a major source of cloud condensation nuclei in the remote marine boundary layer. It has been long thought that over remote oceans, condensation growth is dominated by sulfate that derives from ocean-emitted dimethyl sulfide. In this study, we present the first long-term observational evidence that, contrary to conventional thinking, organics play an even more important role than sulfate in particle growth over remote oceans throughout the year.

Ocean Science

Beaching patterns of plastic debris along the Indian Ocean rim

Ocean Science
DOI 10.5194/os-16-1317-2020
26 November 2020

A large percentage of global ocean plastic enters the Indian Ocean through rivers, but the fate of these plastics is generally unknown. In this paper, we use computer simulations to show that floating plastics beach and end up on coastlines throughout the Indian Ocean. Coastlines where a lot of plastic enters the ocean are heavily affected by beaching plastic, but plastics can also beach far from the source on remote islands and countries that contribute little plastic pollution of their own.

Biogeosciences

Reviews and syntheses: The mechanisms underlying carbon storage in soil

The 4 per 1000 initiative aims to restore carbon storage in soils to both mitigate climate change and contribute to food security. The French National Institute for Agricultural Research conducted a study to determine the carbon storage potential in French soils and associated costs. This paper is a part of that study. It reviews recent advances concerning the mechanisms that controls C stabilization in soils. Synthetic figures integrating new concepts should be of pedagogical interest.

Atmospheric Chemistry and Physics

Global modeling of cloud water acidity, precipitation acidity, and acidinputs to ecosystems

Cloud water pH affects atmospheric chemistry, and acid rain damages ecosystems. We use model simulations along with observations to present a global view of cloud water and precipitation pH. Sulfuric acid, nitric acid, and ammonia control the pH in the northern midlatitudes, but carboxylic acids and dust cations are important in the tropics and subtropics. The acid inputs to many nitrogen-saturated ecosystems are high enough to cause acidification, with ammonium as the main acidifying species.

Geoscientific Model Development

The Making of the New European Wind Atlas – Part 2: Production and evaluation

This is the second of two papers that document the creation of the New European Wind Atlas (NEWA). The paper includes a detailed description of the technical and practical aspects that went into running the mesoscale simulations and the microscale downscaling for generating the climatology. A comprehensive evaluation of each component of the NEWA model chain is presented using observations from a large set of tall masts located all over Europe.

Atmospheric Measurement Techniques

A technical description of the Balloon Lidar Experiment (BOLIDE)

The Balloon Lidar Experiment was the first lidar dedicated to measurements in the mesosphere flown on a balloon. During a 6 d flight, it made high-resolution observations of polar mesospheric clouds which form at high latitudes during summer at ~ 83 km altitude and are the highest clouds in Earth’s atmosphere. We describe the instrument and assess its performance. We could detect fainter clouds with higher resolution than what is possible with ground-based instruments.

Earth Surface Dynamics

Topographic controls on divide migration, stream capture, anddiversification in riverine life

Organisms evolve in ever-changing environments under complex process interactions. We applied a new software modelling tool to assess how changes in river course impact the evolution of riverine species. Models illustrate the climatically and tectonically forced landscape changes that can drive riverine biodiversity, especially where topographic relief is low. This research demonstrates that river course changes can contribute to the high riverine biodiversity found in real-world lowland basins.

Earth System Dynamics

Climate change as an incentive for future human migration

We examine the implications of future motivation for humans to migrate by analyzing today’s relationships between climatic factors and population density, with all other factors held constant. Such analyses are unlikely to make accurate predictions but can still be useful for informing discussions about the broad range of incentives that might influence migration decisions. Areas with the highest projected population growth rates tend to be the areas most adversely affected by climate change.

Geochronology

Resolving multiple geological events using in situ Rb–Sr geochronology:implications for metallogenesis at Tropicana, Western Australia

Using a relatively new dating technique, in situ Rb–Sr geochronology, we constrain the ages of two generations of mineral assemblages from the Tropicana Zone, Western Australia. The first, dated at ca. 2535 Ma, is associated with exhumation of an Archean craton margin and gold mineralization. The second, dated at ca. 1210 Ma, has not been previously documented in the Tropicana Zone. It is probably associated with Stage II of the Albany–Fraser Orogeny and additional gold mineralization.

Atmospheric Measurement Techniques

A feasibility study to use machine learning as an inversion algorithm for aerosol profile and property retrieval from multi-axis differentialabsorption spectroscopy measurements

This paper is about a feasibility study of applying a machine learning technique to derive aerosol properties from a single MAX-DOAS sky scan, which detects sky-scattered UV–visible photons at multiple elevation angles. Evaluation of retrieved aerosol properties shows good performance of the ML algorithm, suggesting several advantages of a ML-based inversion algorithm such as fast data inversion, simple implementation and the ability to extract information not available using other algorithms.

Ocean Science

Connecting flow–topography interactions, vorticity balance, baroclinicinstability and transport in the Southern Ocean: the case of an idealizedstorm track

Ocean Science
DOI 10.5194/os-16-1207-2020
12 November 2020

The dynamical balance of the Antarctic Circumpolar Current and its implications on the functioning of the world ocean are not fully understood and poorly represented in global circulation models. In this study, the sensitivities of an idealized Southern Ocean (SO) storm track are explored with a set of eddy-rich numerical simulations. We show that the classical partition between barotropic and baroclinic modes is sensitive to current–topography interactions in the mesoscale range of 10–100 km.