bluuebunny/crossref_metadata_2025 huggingface dataset:
Inter-annual variability in supraglacial lakes around East Antarctica
Authors: Arthur Jennifer , Stokes Chris , Jamieson Stewart , Carr Rachel , Leeson Amber
Published: March 2021

Surface meltwater ponding can weaken and trigger the rapid disintegration of Antarctic ice shelves which buttress the ice sheet, causing ice flow acceleration and global sea-level rise. While supraglacial lakes (SGLs) are relatively well documented during some years and selected ice shelves in Antarctica, we have little understanding of how Antarctic-wide SGL coverage varies between melt seasons. Here, we present a record of SGL evolution around the peak of the melt season on the East Antarctic Ice Sheet (EAIS) over seven consecutive years. Our findings are based on a threshold-based algorithm applied to 2175 Landsat 8 images during the month of January from 2014 to 2020. We find that EAIS-wide SGL volume fluctuates inter-annually by up to ~80%. Moreover, patterns within regions and on neighbouring ice shelves are not necessarily synchronous. Over the whole EAIS, total SGL volume was greatest in January 2017, dominated by the Amery and Roi Baudouin ice shelves, and lowest in January 2016. Excluding these two ice shelves, SGL volume peaked in January 2020. Preliminary results suggest EAIS-wide total SGL volume and extent are weakly correlated with firn model simulations of firn air content, surface melt and minimum ice lens depth predicted by the regional climate model MAR. On certain ice shelves, years with peak SGL volume correspond with minimum firn air content. This work provides important constraints for numerical ice-shelf and ice-sheet model predictions of future Antarctic surface meltwater distributions and the potential impact on ice-sheet stability and flow.  
A Budyko-like framework for exploring the controls of long-term flood risk in coupled human-flood systems
Authors: Barendrecht Marlies H , Viglione Alberto , Kreibich Heidi , Blöschl Günter
Published: March 2021

Long term dynamics in human-flood systems differ due to differences in hydrological and societal characteristics. By contrasting and comparing different human-flood systems we increase our understanding of which characteristics lead to which dynamics, which might help to counteract unfavorable developments. We propose a framework for comparing human-flood systems analogous to the Budyko one for traditional catchment hydrology. While in the Budyko framework catchments are classified as either water limited or energy limited, in the framework proposed here the human-flood systems are classified as either hydrology limited or exposure limited. In analogy to the precipitation, potential evapotranspiration and actual evapotranspiration components of the Budyko space we formulate the components of the “flood risk space” as hydrological potential loss, manmade potential loss and actual flood loss. The framework is applied to four stylised theoretical systems, investigating how their position in the flood risk space may change under the influence of hydrological, technical and demographic changes. Results show that hydrological changes have the largest effect on a system’s position in the flood risk space: with an increasing skewness and CV systems become more hydrology limited. The framework’s value for comparing empirical case studies is demonstrated through an application to two case studies in Germany: Dresden on the Elbe and Cologne on the Rhine. The framework allows us to identify the differences in dynamics between the two case studies, as they are located in different areas of the flood risk space. The difference in dynamics between the Dresden and Cologne systems seems to be mostly caused by the hydrological parameters (i.e. the skewness) rather than the social parameters. The flood frequency distribution is more skewed in the case of the Elbe in Dresden than in the case of the Rhine in Cologne. Therefore, Dresden experiences more shocks to the system (i.e. unexpectedly large floods) than Cologne.
Past and recent biodiversity profiling in ancient Lake Chalco Mexico by a metagenomics analysis
Authors: Moguel Bárbara , Pérez Liseth , Alcaraz Luis David , Lozano-García Socorro , Herrera-Estrella Luis , Blaz Jazmín , Caballero Margarita , Ávila-Arcos María , Laclette Juan Pedro , Muñoz-Velasco Israel , Ortega-guerrero Beatriz , Becerra Arturo , Romero-Oliva Claudia
Published: March 2021

For decades, paleoecological studies in lake sediments have focused on reconstructing the environments of the past and explaining phenomena linked to climatic variations. Recent advances in high-throughput DNA sequencing have allowed access to environmental DNA (eDNA) and ancient sedimentary DNA (sedaDNA) as a new and efficient proxy for past and present biodiversity. The basin of Mexico (BM) is located in the central part of the Trans-Mexican Volcanic Belt at 2,200 m a.s.l.; with the southern portion harboring the Chalco sub-basin. Lake Chalco is one of the last remaining natural aquatic ecosystems within the ever-expanding urban area surrounding Mexico City. The paleoenvironmental history of this lake has been previously characterized using sedimentological and geochemical proxies, as well as preserved microfossils (diatoms, pollen) with a temporal framework based on multiple radiocarbon dates. However, information for the remaining taxonomic groups and metabolic pathways remained unexplored. Here, we present the first metagenomics-based study for the Holocene in a high-altitude lake in Central Mexico –Lake Chalco. We explored the relationship between the lake’s paleoenvironmental condition and estimations of taxonomic and metabolic profiles across the sedimentary sequence (2.5 meters long). Multiple biological and abiotic variables revealed three main environmental phases: 1) a cool freshwater lake (FW1: 11,500-11,000 cal years BP), 2) a warm hyposaline lake (HS2: 11,000-6,000 cal years BP), and 3) a temperate, subsaline lake (SS3, <6,000 cal years BP). We describe the structure of the microbiota community and taxonomy richness turnover in the three Holocene paleoenvironmental phases. During the past 12 000 years BP the most abundant domains in Lake Chalco sediments were Bacteria, followed by Archaea, and Eukarya (36,722 genera). The analysis of functional proteins showed high biodiversity with a total of 27,636,243 proteins identified, but it was only possible to annotate 3,227,398 of them. Also, we identified several genes associated with some relevant pathways, such as methanogenesis. Altogether, this study allowed us to reconstruct the natural history of lake Chalco and its surroundings.
A shift to predominant multi-year sea ice conditions in the Baffin Bay and North Atlantic Ocean during the Holocene-Glacial transition inferred from the EGRIP ice core
Authors: Segato Delia , Burgay Francois , Maffezzoli Niccolò , Spagnesi Azzurra , Turetta Clara , Scoto Federico , Dallo Federico , Zannoni Daniele , Erhardt Tobias , Jensen Camilla Marie , Saiz-Lopez Alfonso , Kjær Helle Astrid , Dahl-Jensen Dorthe , Barbante Carlo , Spolaor Andrea
Published: March 2021

Arctic sea ice has been melting at unprecedented rates in the past decades. Understanding past sea ice variability is of paramount importance to contextualize recent changes and constrain global climate models. Bromine enrichment (Brenr), relative to sea-water ratio, has been introduced as a proxy of first-year sea ice conditions within the ocean region influencing the ice core location (Spolaor et al., 2013). Brenr has been measured in ice cores from Greenland, that is the NEEM and RECAP cores. NEEM sea ice proxies are influenced by the region of the Canadian Arctic and Baffin Bay, while for the RECAP core it is mainly the North Atlantic Ocean. In this study we present the first high-resolution record of bromine enrichment from the EGRIP ice core in Greenland for the last 15.7 kyr BP, covering the Holocene-Glacial transition.

From preliminary back-trajectory analyses we suggest that EGRIP sea ice proxy sources are located in a wide region in the Baffin Bay and North Atlantic Ocean. We find EGRIP Brenr values of ~1 during cold periods, that is the Younger Dryas (12.9 – 11.7 kyr BP) and the last part of the Oldest Dryas (15.7 – 14.7 kyr BP), which we associate with predominant multi-year sea ice conditions. During warmer periods, instead, we observe higher Brenr values, ~3 for the Bølling-Allerød period (14.7 – 12.9 kyr BP) and progressively higher values from the early Holocene onwards, likely associated with an increased seasonal sea ice area. EGRIP Brenr is consistent with NEEM and RECAP records and it has the potential to extend our knowledge on Arctic past sea ice variability.

 

Bibliography

Spolaor, A., Vallelonga, P., Plane, J. M. C., Kehrwald, N., Gabrieli, J., Varin, C., Turetta, C., Cozzi, G., Kumar, R., Boutron, C., and Barbante, C.: Halogen species record Antarctic sea ice extent over glacial–interglacial periods, Atmos. Chem. Phys., 13, 6623–6635, https://doi.org/10.5194/acp-13-6623-2013, 2013.
Temperature and moisture controls on non-growing season CO2 emissions in laboratory incubations with soils from northern peatlands
Authors: Byun Eunji , Rezanezhad Fereidoun , Fairbairn Linden , Basiliko Nathan , Price Jonathan , Quinton William , Roy-Léveillée Pascale , Webster Kara , Van Cappellen Philippe
Published: March 2021

Canada has extensive peat deposits in northern high latitude wetlands and permafrost ecosystems. Peat accumulation represents a natural long-term carbon sink attributed to the cumulative excess of growing season net ecosystem production over non-growing season net mineralization. However, near-surface peat deposits are vulnerable to climate change and permafrost landscape transition. One specific concern is a potential rapid increase in the non-growing season carbon loss through enhanced organic matter mineralization under a warming climate. Our experimental study explores the response of peat CO2 exchanges to (1) temperature, using the conventional Q10 parameter, and (2) moisture content. The observed responses are expected to reflect, at least in part, differential soil microbial adaptations to varying wetland conditions, across two northern ecoclimatic zones. Laboratory incubations were carried out with shallow peat samples from different depths collected at seven Canadian wetland sites and adjusted to five moisture levels. For each subsample (varying by site, depth and moisture content), CO2 fluxes were measured at 12 sequential temperature settings from -10 to 35˚C. For each subsample, the data were fitted to an exponential equation to derive a Q10 value. In general, boreal peat samples were more temperature sensitive than temperate peat. The optimum moisture level for CO2 release was determined for all the subsamples and related to variations in wetland vegetation and landform types. As a general trend, increasing water saturation reduced the CO2 release rate from a given subsample. We further tested a flexible curve-fitting equation, as recently proposed on a theoretical basis, to recompile the data by ecoclimatic peat type and to account for the non-growing season dynamics. These findings will contribute to Canada’s national carbon budget model by guiding the development and calibration of the peatland module.
Modelling plant uptake of Cd, Ni and Pb from mobile fractions and release rates obtained by the EUF-method
Authors: Sager Manfred , Jelecevic Anto , Liebhard Peter
Published: March 2021

In order to predict concentrations in green plants from kinetic data as well as from mobile soil fractions from geogenically enriched areas, soils from historic mining and smelting sites in Styria (Austria) were used to grow lettuce in pot experiments. Lettuce is known for high accumulation of Ni and Cd in the shoots as well, but in our case, uptakes remained low. Addition of a mixed metal salt solution resulted in high Ni concentrations in the plants, contrary to Cd and Pb. Effects of mineral fertilizers and metal salt additions upon plant metal uptake and N resp C/N shifts were monitored and combined with results from batch-extraction as well as with release rates and released amounts obtained by a modified EUF (electro-ultra-filtration) method.

The release obtained by EUF in 0,002M DTPA was modelled by linear, logarithmic, parabolic (√) and quadratic dependence versus time, from original as well as from cumulated datasets. As expected, addition of soluble salts increased the release, whereas addition of PK fertilizer lowered the release of the metals from soil. Thus, food contamination hazards can be lowered by adequate agricultural activities. Plant uptake by nickel got clearly enhanced by metal salt additions, whereas effects of added cadmium and lead were lower. Correlations between plant uptake and release rates resp. released amounts were in the same range, whatever model was used.
Hyper-resolution hydrological modelling to assess water and food security in Malawi
Authors: Anghileri Daniela , Vergopolan Noemi , Gebrechorkos Solomon , Sheffield Justin
Published: March 2021

Agriculture is a key sector in fighting hunger in Sub Saharan Africa. Almost 95% of the agriculture in Africa is rain-fed and smallholder farmers play a crucial role as they produce most of the food consumed by local populations. These characteristics make the SSA agricultural landscape very diverse and particularly vulnerable to weather extremes. The ability of forecasting hydrological variability has increased in recent years due to advancements in the understanding of hydro-climatic processes, growing availability of high-resolution remote sensing datasets, and the increase of computational power, which has promoted the development of high-quality computer-based hydrological models. When adopted in data scarce regions, these models provide new insight into the hydrological budget and in characterizing the hydrological variability of these areas. In this work, we combine the hyper-resolution hydrological model HydroBlocks and the river routing model RAPID to simulate the spatial and temporal heterogeneity of the land surface processes in Malawi at 30 m resolution. The model simulations show high variability of the hydrological variables, particularly soil moisture, across the country. We use these results to further analyse water and food security indicators in the transboundary catchment of Lake Chilwa shared between Malawi and Mozambique. The start and duration of the maize cropping season and the lake level show a large interannual variability which allow us to quantify the weather-related vulnerability of the local smallholder farming system. This work is part of the research activities of the UKRI-GCRF funded project “Building research capacity for sustainable water and food security in drylands of sub-Saharan Africa” (BRECcIA - http://www.gcrf-breccia.com/).
Propagation of satellite orbit modelling deficiencies into the global GNSS solutions – simulation-based study
Authors: Kalarus Maciej , Dach Rolf , Villiger Arturo , Jaeggi Adrian
Published: March 2021

The Non-Gravitational Perturbations (NGP), out of which the Solar Radiation Pressure (SRP) is the largest, have a significant impact on GNSS satellite orbits. In addition to the SRP, other relevant perturbations should also be taken into account, as this may result in substantial modelling errors if underestimated. Particularly, the force model should also consider Earth’s albedo in terms of the emitted and reflected radiation, as well as a physical satellite model (box-wing) with its optical and thermal properties.
GNSS satellite orbit modelling may suffer from deficiencies for various reasons (simplification of the complexity of the used model or uncertainty of the input information). The impact of such model errors on global GNSS data analyses is assessed in an error propagation study based on simulated observations. The influence of artificially introduced orbit errors on estimated parameters, e.g. Earth rotation parameters, orbit parameters (initial conditions and dynamical orbit parameters), station coordinates, station-wise troposphere parameters, as well as receiver and satellite clock corrections is investigated. In this study a dedicated simulation environment is used to analyse the relation between results and certain individual shortcomings in the NGP models. In addition, apart from a commonly used epoch-wise clock estimation, the analytical models for satellite clock corrections are introduced in order to exploit the high stability of the passive H-masers on-board the Galileo satellites. The simulation environment also allows to assess how the impact of float- versus fixed-ambiguities.
Finally, simulation-based analyses offer an excellent framework for more detailed validations and further refinements of the physical satellite models, which will consequently stabilize the global solution.
An Assessment of Observed and Simulated Temperature Variability in Sierra de Guadarrama (Spain)
Authors: Vegas Cañas Cristina , González Rouco J. Fidel , Navarro Montesinos Jorge , García Bustamante Elena , Lucio Eceiza Etor E. , García Pereira Félix , Rodríguez Camino Ernesto , Chazarra Bernabé Andrés , Álvarez Arévalo Inés
Published: March 2021

This work provides a first assessment of temperature variability from interannual to multidecadal timescales in Sierra de Guadarrama, located in central Spain, from observations and regional climate model (RCM) simulations. Observational data are provided by the Guadarrama Monitoring Network (GuMNet; www.ucm.es/gumnet) at higher altitudes, up to 2225 masl, and by the Spanish Meteorological Agency (AEMet) at lower sites. An experiment at high horizontal resolution of 1 km using the Weather Research and Forecasting (WRF) RCM, feeding from ERA Interim inputs, is used. Through model-data comparison, it is shown that the simulations are annually and seasonally highly representative of the observations, although there is a tendency in the model to underestimate observational temperatures, mostly at high altitudes. Results show that WRF provides an added value in relation to the reanalysis, with improved correlation and error metrics relative to observations.

The analysis of temperature trends shows a warming in the area during the last 20 years, very significant in autumn. When spanning the analysis to the whole observational period, back to the beginning of the 20th century at some sites, significant annual and seasonal temperature increases of 1℃/decade develop, most of them happening during de 1970s, although not as intense as during the last 20 years.

The temporal variability of temperature anomalies in the Sierra de Guadarrama is highly correlated with the temperatures in the interior of the Iberian Peninsula. This relationship can be extended broadly over south-western Europe.
Data assimilation of GRACE terrestrial water storage to improve sea level rise estimates and isolate anthropogenic influences
Authors: Scheliga Ann , Girotto Manuela
Published: March 2021

Sea level rise (SLR) projections rely on the accurate and precise closure of Earth’s water budget. The Gravity Recovery and Climate Experiment (GRACE) mission has provided global-coverage observations of terrestrial water storage (TWS) anomalies that improve accounting of ice and land hydrology changes and how these changes contribute to sea level rise. The contribution of land hydrology TWS changes to sea level rise is much smaller and less certain than contributions from glacial melt and thermal expansion. Although land hydrology TWS plays a smaller role, it is still important to investigate to improve the precision of the overall global water budget. This study analyzes how data assimilation techniques improve estimates of the land hydrology contribution to sea level rise. To achieve this, three global TWS datasets were analyzed: (1) GRACE TWS observations alone, (2) TWS estimates from the model-only simulation using Catchment Land Surface Model, and (3) TWS estimates from a data assimilation product of (1) and (2). We compared the data assimilation product with the GRACE observations alone and the model-only simulation to isolate the contribution to sea level rise from anthropogenic activities. We assumed a balanced water budget between land hydrology and the ocean, thus changes in global TWS are considered equal and opposite to sea level rise contribution.  Over the period of 2003-2016, we found sea level rise contributions from each dataset of +0.35 mm SLR eq/yr for GRACE, -0.34 mm SLR eq/yr for model-only, and a +0.09 mm SLR eq/yr for DA (reported as the mean linear trend). Our results indicate that the model-only simulation is not capturing important hydrologic processes. These are likely anthropogenic driven, indicating direct anthropogenic and climate-driven TWS changes play a substantial role in TWS contribution to SLR.
Arctic Freshwater in CMIP6: Declining Sea Ice, Increasing Ocean Storage and Export
Authors: Zanowski Hannah , Jahn Alexandra , Holland Marika
Published: March 2021

Recently, the Arctic has undergone substantial changes in sea ice cover and the hydrologic cycle, both of which strongly impact the freshwater storage in, and export from, the Arctic Ocean. Here we analyze Arctic freshwater storage and fluxes in 7 climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6) and assess their agreement over the historical period (1980-2000) and in two future emissions scenarios, SSP1-2.6 and SSP5-8.5. In the historical simulation, few models agree closely with observations over 1980-2000. In both future scenarios the models show an increase in liquid (ocean) freshwater storage in conjunction with a reduction in solid storage and fluxes through the major Arctic gateways (Bering Strait, Fram Strait, Davis Strait, and the Barents Sea Opening) that is typically larger for SSP5-8.5 than SSP1-2.6. The liquid fluxes through the gateways exhibit a more complex pattern, with models exhibiting a change in sign of the freshwater flux through the Barents Sea Opening and little change in the flux through the Bering Strait in addition to increased export from the remaining straits by the end of the 21st century. A decomposition of the liquid fluxes into their salinity and volume contributions shows that the Barents Sea flux changes are driven by salinity changes, while the Bering Strait flux changes are driven by compensating salinity and volume changes. In the straits west of Greenland (Nares, Barrow, and Davis straits), the models disagree on whether there will be a decrease, increase, or steady liquid freshwater export in the early to mid 21st century, although they mostly show increased liquid freshwater export in the late 21st century. The underlying cause of this is a difference in the magnitude and timing of a simulated decrease in the volume flux through these straits. Although the models broadly agree on the sign of late 21st century storage and flux changes, substantial differences exist between the magnitude of these changes and the models’ Arctic mean states, which shows no fundamental improvement in the models compared to CMIP5.
Local Seismicity indicates basin inversion in the Ligurian Sea 
Authors: Thorwart Martin , Dannowski Anke , Grevemeyer Ingo , Lange Dietrich , Kopp Heidrun , Petersen Florian , Crawford Wayne , Paul Anne ,   AlpArray Working Group
Published: March 2021

The Alpine orogen and the Apennine system are part of the complex tectonic setting in the Mediterranean Sea caused by the convergence between Africa and Eurasia. Between 30 Ma and 15 Ma the Calabrian subduction retreated in a southeast direction pulling Corsica and Sardinia away from the Eurasian landmass. In this extensional setting, the Ligurian Sea was formed as a back-arc basin. The rifting jumped 15 Ma ago in the Tyrrhenian Sea leaving Corsica and Sardinia in a stable position relative to Eurasia.

Within the framework of the AlpArray research initiative a long-term seismological experiment was conducted in the Ligurian Sea to investigate the lithospheric structure and the seismicity in the Ligurian basin. The passive seismic network consisted of 29 broad-band ocean bottom stations from Germany and France. It was in operation between June 2017 and February 2018.

Two seismicity clusters occurred in the centre of the Ligurian Basin. The 18 earthquakes are located in the lower crust and in the upper-most mantle at depths between 10 km and 16 km. Re-location was performed only using picks from the OBS in the centre of the Ligurian Sea to avoid artifacts from the complex 3D velocity structure of the basin. Mantle refractions Pn and Sn have apparent velocities of 8.2 km/s and 4.7 km/s. The low Vp-Vs-ratio of 1.72 indicates a more brittle behaviour of the mantle material.

Fault plane solutions were determined for four events using also the data of land stations in southern France, Corsica, Sardinia and northern Italy. The focal mechanisms are thrust faulting. Fault planes strike in a NE-SW direction, coinciding with the alignment of the events and the direction of the basin axis.

We interprete the two earthquake clusters related to the inversion of the Ligurian Basin where the basin’s centre is under compression and stresses are taken up by reactivated faults in the crust and uppermost mantle. The compressional forces could be caused by the convergence of Africa and Europe. In general, observations of earthquakes in continental mantle lithosphere are rare and they reveal on the one hand a strengthening of the crust and uppermost mantle during rifting and on the other hand they support the interpretation that rifting failed in the northern Ligurian Basin.

 
Effect of early Oligocene cooling on the deep-sea benthic foraminifera at IODP hole 1138A, Kerguelen Plateau (Southern Ocean)
Authors: Kumar Rakesh , Maurya Abhayanand Singh , Singh Dharmendra Pratap
Published: March 2021

Benthic foraminifera are typical unicellular marine fauna forming calcareous tests that are commonly used as a proxy to infer the past climatic variabilities. To study the benthic foraminiferal response, we collected 146 samples from IODP hole 1138A, the Southern Ocean (Indian Sector, water depth of 1140 m). We computed various diversity parameters of benthic foraminifera, i.e., Shannon-weaver index (H(S)), Equitability (E'), Hurlbert's diversity index (Sm), Fisher's alpha index (α), and Species richness (S). The calculated diversity indices with the abundance of dominant early Oligocene (33.5 to 31.2 million years ago) benthic foraminifera taxa reveal significant palaeoceanographic changes viz. cooling and warming events in the Southern Ocean. The early Oligocene interval exhibits an unusual condition at hole 1138A dominated by high oxygen species, intermediate food supply, well-ventilated, cold, and corrosive bottom water condition. The calculated values of all diversity parameters increase from 33.7 Ma to 32.8 Ma while attaining the maximum from 32.8 Ma to 32.2 Ma, followed by a decreasing trend. The highest value of diversity parameters coincides with the Oi-1 events. The relative increase in the species diversity between Oi-1 (33.5 Ma) and Oi-1b (31.7 Ma) events correspond to the brief interruption of Warm Saline Deep Water (WSDW). The enhanced values of low species diversity by high seasonality and relatively cold, strong bottom-water currents after Eocene-Oligocene Transition (EOT; 33.9 Ma) and after Oi-1b (31.7 Ma) event relates to the intensification of Antarctic Circumpolar Current (ACC) and Antarctic Bottom Water (AABW) along with the substantial buildup of the southern hemisphere glaciation. The abrupt decrease of abundance of species such as Nuttallides umbonifera, Astrononion echolsi, and Uvigerina peregerina at the end of the studied interval (31.3 Ma) further corroborates the major southern hemisphere glaciation. The present study of the benthic foraminiferal abundance and diversity indices therefore reveals the cooling of the Southern Ocean at early and late stages of the studied interval interrupted by a short-lived warming event. The study further enhances the understanding of paleo-marine ecology by evaluating the response of deep-sea benthic foraminifera to global climate change.

Keywords: Kerguelen Plateau, Benthic Foraminifera, Southern Ocean, early Oligocene
The story of a tree and what its tells us about our life
Authors: Bruun John
Published: March 2021

Our natural world presents many fascinating and often bizarre phenomena to us. The way primary producers convert sunlight with nutrients as part of the existence of life is simply amazing. This gives rise to phytoplankton communities in the oceans and the growth of trees across the world. The signals of our dynamic world, its chronology and patterns of how this life grows are indelibly written into these trees as well as in mineral and oceanic floor strata. In this session I’d like to symbolically ask a generic tree “what were the choices made 150 years ago that led to our current warming?” As interdisciplinary scientists – the thinking process we use whilst embedded in logic and reason – is also closely related to our personal creative and imagining aptitudes. Our social norms also reflect the scope of decisions that we choose to talk about and identify with. By enabling a platform that frames the co-existence of contemporary scientific reasoning together with the artistic expression we re-imagine and further create possibilities, through stories, drawing, metaphor, sound and dance. With this, a wider community of scientists can engage with topics that previously seem technically obscure. A deeper public understanding of geosciences also develops. In the first part of this session I’ll narrate a story of climate change choices see by the generic tree seen over the last 500 years linking this to tree ring records, personal geoscience learning and the EGU photo archive. In the second part – I invite the audience to share their creative points of view about these climatic era’s and to further explore what stories this generic tree may be telling us about our world. The aim of this work is to enable group participation and share creative ideas. My hope is that we may envisage new combinations of opportunities about climatic futures that can enable a more resilient future for us all.
Extreme precipitation events during the South Asian summer monsoon season in the past century
Authors: Falga Renaud , Wang Chien
Published: March 2021

The South Asian monsoon system impacts the livelihoods of over a billion people. While the overall monsoon rainfall is believed to have decreased during the 20th century, there is a good agreement that the extreme precipitation events have been rising in some parts of India. As an important part of the Indian population is dependent on rainfed agriculture, such a rise in extremes, along with resulting flood events, can be all the more problematic. Although studies tend to link this rise in extreme events with anthropogenic forcing, some uncertainties remain on the exact causes. In order to examine the correlation between anthropogenic forcings and the different trends in extreme events, we have analyzed the high-resolution daily rainfall data in the past century delivered by the Indian Meteorological Department alongside several other economic and ecological estimates. The results from this analysis will be presented in detail.
Unprecedented decline of sea ice thickness in Fram Strait in 2017-2018
Authors: Sumata Hiroshi , de Steur Laura , Divine Dmitry , Pavlova Olga , Gerland Sebastian
Published: March 2021

Fram Strait is the major gateway connecting the Arctic Ocean and the northern North Atlantic Ocean where about 80 to 90% of sea ice outflow from the Arctic Ocean takes place. Long-term observations from the Fram Strait Arctic Outflow Observatory maintained by the Norwegian Polar Institute captured an unprecedented decline<!-- Reply to Sebastian Gerland (2021/01/12, 15:45): "..."
I slightly modified the sentence to mention this. --> of sea ice thickness in 2017 – 2018 since comprehensive observations started in the early 1990s. Four Ice Profiling Sonars moored in the East Greenland Current in Fram Strait simultaneously recorded 50 – 70 cm decline of annual mean ice thickness in comparison with preceding years. A backward trajectory analysis revealed that the decline was attributed to an anomalous sea level pressure pattern from 2017 autumn to 2018 summer. Southerly wind associated with a dipole pressure anomaly between Greenland and the Barents Sea prevented southward motion of ice floes north of Fram Strait. Hence ice pack was exposed to warm Atlantic Water in the north of Fram Strait 2 – 3 times longer than the average year, allowing more melt <!-- Reply to Sebastian Gerland (2021/01/12, 15:46): "..."
I would like to keep this sentence as it is, since the analysis implies sea ice melt occurred in the vicinity of Fram Strait in winter (probably due to ocean heat flux), though we don’t have direct measurements of 2018 event.
This could be an interesting implications of this study, and seeds for further investigation.
-->to happen. At the same time, the dipole anomaly was responsible for the slowest observed annual mean ice drift speed in Fram Strait in the last two decades. As a consequence of the record minimum of ice thickness and the slowest drift speed, the sea ice volume transport through the Fram Strait dropped by more than 50% in comparison with the 2010 – 2017 average.
Combining branch-scale COS/CO2 exchange and canopy-scale SIF measurements to disentangle the effects of high VPD and low soil moisture in mature pine trees under field conditions
Authors: Qubaja Rafat , Stern Rafael , Oz Itay , Cochavi Amnon , Muller Jonathan , Yakir Dan
Published: March 2021

During the regular seasonal drought conditions in our semi-arid pine forest, soil water content decrease below the 16% threshold of no transpirable soil water availability, and VPD increase to values of >5 kPa. Soil drought in one forest plot was eliminated by using supplemental drip irrigation during summer. We used automatic branch chambers to measure CO2/H2O exchange together with laser-based COS exchange, and retrieving canopy sun induced fluorescence (SIF) using a high-resolution spectrometer above the canopy that was moved between the control and irrigated plots on a weekly basis. Using these research tools, we investigated the ecophysiological response (including rates of gas exchange, conductances, and photochemical response) of the mature pine trees to the differential effects of soil and atmospheric droughts. Leaf relative uptake (LRU) ratio of COS to CO2 fluxes was used to constrain estimates of carbon assimilation (An) and changes in the An/gl ratio (where gl is leaf conductance), and leaf COS and H2O exchange fluxes were also used to partition leaf conductance. We will report on the first seasonal cycle of COS and CO2 fluxes, LRU and SIFA of mature pine trees under field conditions in the semi-arid forest, which includes the summer dry stress period, the recovery during the transition to the winter wet season, and the spring peak activity period.
TSI and TOR measurements with CLARA onboard NorSat-1
Authors: Haberreiter Margit , Finsterle Wolfgang , Montillet Jean-Philippe , Walter Benjamin , Andersen Bo , Schmutz Werner
Published: March 2021

Total Solar Irradiance (TSI) is one of the Essential Climate Variables (ECV) identified by the World Meteorological Organization's Global Climate System (GCOS). The Compact Lightweight Absolute RAdiometer (CLARA) experiment onboard the Norwegian micro satellite NorSat-1 is a SI traceable radiometer and was launched July 14, 2017 with the primary science goal to measure TSI from space. We present the latest status of the data and degradation correction obtained with this SI-traceable radiometer. Besides TSI, CLARA also measures the total outgoing radiation (TOR) at the top of the Earth atmosphere on the night side of Earth, which is extremely important to understand the Earth Radiation Budget. It is to our knowledge the first time that TSI and the emitted radiation from Earth are measured simultaneously with one SI-traceable absolute radiometer. We will compare the CLARA TSI and TOR time series with other available datasets. Ultimately, we aim towards determining the Earth Energy Imbalance from space. We will discuss the achievements and limitations in direction of this goal.
Improving the Classification Accuracy of Fragmented Cropland by using an Advanced Classification Algorithm
Authors: Moharana Dr. Shreedevi , Kambhammettu Dr. BVNP , Chintala Mr. Syam , Sandhya Rani Ms. Arjangi , Avtar Dr. Ram
Published: March 2021

Fragmented crop land and marginal landholdings play an important role to classify the landuse and adopt different cropping and management practices. Here the implementation crop classification algorithms are very much difficult and produce results with lower accuracy. Static imagery captured in the optical bands are often contaminated with cloud cover and fail to detect the phenological as well as the structural changes happening during the crop growth. This is very common and most typical in Indian climatic condition. Here, during monsoon period capturing temporal satellite images of the crop periods is a very challenging task. Therefore, the present study aims at application of a novel crop classification algorithm that utilizes the temporal patterns of synthetic aperture radar (SAR) datasets from Sentinel-1 in mapping of landuse of an agriculture system, that is fragmented, small and heterogeneous in nature. Here we used different polarization of Sentinel-1 datasets and developed the temporal crop patterns of different crops grown in semi-arid region of India. Further, an advanced classification algorithm such as time weighted dynamic time wrapping (TWDTW) is employed to classify the cropland with a higher accuracy. Pixel based image analysis was carried out and tested their applicability for cropland mapping. In-situ data sets are collected from the study site to validate the exhibited results from classification outputs. The overall accuracy of the pixel based TWDTW method performed very good results with accuracy of 63 %. The Kappa coefficient is found to be 0.58. The findings confirmed that the pixel based TWDTW algorithm has the potential to delineate the croplands, which were subjected to varying irrigation treatments and management practices, using sentinel-1 datasets.

Keywords: crop classification, landuse, image analysis, Sentinel-1, TWDTW
A two-step role for plasma expansion in solar wind heat flux regulation
Authors: Innocenti Maria Elena , Boella Elisabetta , Tenerani Anna , Velli Marco
Published: March 2021

Already several decades ago, it was suggested that kinetic instabilities play a fundamental role in heat flux regulation at relatively large distances from the Sun, R> 1 AU [Scime et al, 1994]. Now, Parker Solar Probe observations have established that this is the case also closer to it [Halekas et al, 2020].

Electron scale instabilities in the solar wind are driven and affected in their evolution by the slow, large scale process of solar wind expansion, as demonstrated observationally [Stverak et al, 2008; Bercic et al, 2020], and via fully kinetic Expanding Box Model simulations [Innocenti et al, 2019b].

Now, connecting the dots, we examine an indirect role of plasma expansion in heat flux regulation in the solar wind. We show, as a proof of principle, that plasma expansion can modify heat flux evolution as a function of heliocentric distance, with respect to what is expected within an adiabatic framework, due to the onset of kinetic instabilities, in this case, an oblique firehose instability developing self consistently in the presence of a core and suprathermal electron population [Innocenti et al, 2020].

This result highlights, once again, the deeply multi scale nature of the heliospheric environment, that calls for advanced simulation techniques. In this work, the simulations are done with the fully kinetic, semi-implicit [Markidis et al, 2010], Expanding Box Model [Velli et al, 1992] code EB-iPic3D [Innocenti et al, 2019a].
Toward constraining Saturn's rotation rate by interior modeling
Authors: Nettelmann Nadine , Fortney Jonathan J.
Published: March 2021

The rotation rate of the outer planet Saturn is not well constrained by classical measurements of periodic signals [1]. Recent and diverse approaches using a broad spectrum of Cassini and other observational data related to shape, winds, and oscillations are converging toward a value about 6 to 7 minutes faster than the Voyager rotation period.
Here we present our method of using zonal wind data and the even harmonics J2 to J10 measured during the Cassini Grand Finale tour [2] to infer the deep rotation rate of Saturn. We assume differential rotation on cylinders and generate adiabatic density profiles that match the low-order J2 and J4
values. Theory of Figures to 7th order is applied to estimate the differences in the high-order moments J6 to J10 that may result from the winds and the assumed reference rotation rate. Presented results are preliminary as the method is under construction [3].

[1] Fortney, Helled, Nettelmann et al, in: 'Saturn in the 21st century', Cambridge U Press (2018)
[2] Iess, Militzer, Kaspi, Science 364:2965 (2019)
[3] Nettelmann, AGU Fall Meeting, P066-0007 (2020)

 
Trace metals accumulation on the Po river prodelta, North Adriatic Sea
Authors: Riminucci Francesco , Capotondi Lucilla , Ravaioli Mariangela
Published: March 2021

The Po River delta (northern Italy) is a complex system composed of terrestrial, transitional and coastal-marine ecosystems strongly influenced by different natural and anthropogenic stressors. In this study, we aimed to provide the anthropic impact during the last 200 years through geochemical concentration of heavy metals. In order to reach this objective, trace Metals (TMs: Pb, Zn, Cu, Cr, Cd and Ni), major elements (Al, Fe and Mn) and natural/artiﬁcial radionuclides (210Pb/137Cs) were analysed on the sediment core (EL14-C01) collected in 2014 in the Po River prodelta. We assumed the TMs mean concentrations during the pre-industrial time (before 1850) as the natural background in this area. Sediments deposited after 1850 exhibited a TMs gradual rise compared to the concentrations recorded in the pre-industrial era, in particular Pb, Zn and Cu (PZC). PZC vertical profiles show that the contamination has increased dramatically after the Second World War, during the so called ‘‘Italian Economic Miracle’’ period, exceeding up to 2.5, 2 and 1.5 (Pb>Zn>Cu) times the concentrations of the pre-industrial era. Post-war years saw the birth of the mechanical, chemical, ceramics Italian industries, and the switch from coal to oil and the plastic derivatives it entailed (Romano et al. 2013). The PZC concentrations reached the maximum between 1970s and 1980s, in agreement with anthropogenic atmospheric emissions changes. The distributions of ZPC indicate a sharp contamination decrease from the second half of the 1980s. Probably this reduction was related to the introduction of the Italian Law 319/76 and to the implementation of anti-pollution policies on automotive Pb (unleaded fuels). Recently, the levels of anthropogenic ZPC pollution are similar to the pre-WWII values. During the XXth century, the geochemical analysis show some TMs/Al peaks corresponding to the seven major Po floods with discharges above 8000 m3/s occurred in 1917, 1926, 1928, 1951, 1976, 1994, and 2000.
Typology of Hazard Event Severity Metrics for Multi-Hazard Research
Authors: Wang Yi (Victor) , Sebastian Antonia
Published: March 2021

In the scholarly field of hazards, adverse impacts of a hazard event are interpreted as the result of interactions among hazard elements, exposure of entities of value, and vulnerability of the exposed entities. The severity of hazard elements is usually communicated as a magnitude or intensity. Such hazard event magnitude or intensity metrics correspond to the expected damages due to a hazard event given an average exposure and vulnerability. These severity metrics can be used to facilitate hazard communication and enhance emergency management. However, hazard event severity metrics for singular hazard types such as the earthquake Richter magnitude and the Saffir-Simpson hurricane wind scale cannot be readily adapted for multi-hazard comparative analyses. The first and foremost challenge to such comparative analyses is a lack of conceptual framework to systemically classify different hazard event severity metrics. In this presentation, we introduce a four-dimensional typology of hazard event severity metrics for hazard research within a multi-hazard context. The four dimensions include the spatial, temporal, applicational, and indicial dimensions. Based on a literature review on 67 existing hazard event magnitude or intensity scales for 21 singular hazard types, we demonstrate that the proposed typology can be applied to classify hazard event severity metrics. We further implement the proposed typology to two newly developed equivalent hazard event severity metrics called the Gardoni Scale and the Murphy Scale to showcase the utility of the proposed typology in facilitating quantification of hazard severity across different hazard event types.
High-resolution air-quality observations onboard commercial Zeppelin flights in Germany 
Authors: Tillmann Ralf , Rohrer Franz , Gkatzelis Georgios I. , Winter Benjamin , Wesolek Christian , Schuldt Tobias , Hundt Morten , Aseev Oleg , Kiendler-Scharr Astrid
Published: March 2021

A Zeppelin NT airship has been used as a platform for in-situ measurement of greenhouse gases and air pollutants in the planetary boundary layer (PBL). The Zeppelin especially with its long flight endurance, low air speed and potential high payload fills a gap between stationary ground based and remote sensing measurements, payload limited UAV based air monitoring, long range-high-altitude aircraft, and satellite observations. Its flight properties render unique applications for the observation of PBL dynamics and air quality monitoring. Highly resolved spatial and temporal trace gas measurements provide input required for modelling of air pollution and validation of emission inventories.

The core instrument deployed was a novel Quantum Cascade Laser (QCL) based multi-compound gas analyzer (MIRO Analytical AG) to measure in-situ concentrations of 10 greenhouse gases and air pollutants simultaneously. The analyzer measured CO2, N2O, H2O and CH4, and the pollutants CO, NO, NO2, O3, SO2 and NH3 with high precision and a measurement rate of 1 Hz. The instrument was operated remotely without the need of on-site personnel. The instrument package was complemented by electrochemical sensors for NO, NO2, Ox and CO (alphasense), an optical particle counter (alphasense), temperature, humidity, altitude and position monitoring. Three campaigns of two weeks each were conducted in 2020 comprising unattended operation during commercial passenger flights.

The acquired data set will be discussed in regard to (1) diurnal height profiles of trace gases such as NO2, (2) a detailed source attribution by fingerprinting, and (3) a comparison to observations from ground-based monitoring stations. The results demonstrate the QCL spectrometer as an all-in-one solution for air-borne trace gas monitoring. By measuring 10 compounds at once it helps to greatly reduce payload, space requirements and power consumption.