bluuebunny/crossref_metadata_2025 huggingface dataset:
Hunting down the late Miocene-early Pliocene biogenic bloom in the Tasman Sea: an integrated study at IODP Site U1506
Authors: Gastaldello Maria Elena , Agnini Claudia , Dallanave Edoardo , Westerhold Thomas , Lam Adriane R. , Drake Michelle K. , Dickens Gerald R. , Sutherland Rupert , Alegret Laia
Published: March 2021

The latest Miocene-early Pliocene biogenic bloom is a poorly understood paleoceanographic event that has been traditionally related to increased primary productivity; and associated changes in the marine carbon cycle. In order to identify this event in the Tasman Sea, we carried out an integrated study at IODP Site U1506. First, we have constructed an age model based on an integrated approach (i.e. biostratigraphy, astrocyclostratigraphic tuning). This permits the identification of the precise position as well as the duration of the biogenic bloom in the Tasman Sea but also the calculation of sedimentation rates across the study interval. In this framework, we generated quantitative micropaleontological records (benthic and planktic foraminifera and calcareous nannofossils) and a low-resolution carbon and oxygen stable isotope records on Cibicidoides mundulus and Trilobatus sacculifer across an interval spanning from 233.50 to 81.75 m CSF-A (Tortonian, late Miocene to Zanclean, early Pliocene). Quantitative assemblage work and statistical analyses on the resulting dataset point to increased export productivity in the lower part of the interval (between CNM15 and CNM18, Backman et al., 2012), as inferred from benthic foraminiferal assemblages dominated by taxa (e.g. Uvigerina and Ehrenbergina) that have been reported to be common across the biogenic bloom in the Indian Ocean (Dickens and Owen, 1999). The paleoecological analysis of these assemblages suggests eutrophic conditions at the seafloor and low oxygen concentration of bottom waters.

Reference

Backman, J., Raffi, I., Rio, D., Fornaciari, E., & Pälike, H., 2012. Biozonation and biochronology of Miocene through Pleistocene calcareous nannofossils from low and middle latitudes. Newsletters on Stratigraphy, 45(3), 221–244.

Dickens, G.R. and Owen, R.M., 1999. The latest Miocene-early Pliocene biogenic bloom: A revised Indian Ocean perspective. Marine Geology, 161: 75-91.

Acknowledgments

University of Padova DOR grant, CARIPARO Foundation Phd scholarship.

Spanish Ministry of Economy and Competitiveness and FEDER funds (PID2019-105537RB-I00).
Demonstrating the Potential of EO for the Agro-Insurance Sector
Authors: Seewald Michaela , Ryter Ralf , Van Hoolst Roel , Tits Laurent , Shynkarenko Ian , Shynkarenko Roman
Published: March 2021

Agriculture provides essential social benefits: supply of food and commodities, economic development and employment. However, agriculture is under growing pressure, arising from soil degradation, water scarcity, natural hazards and weather extremes due to changes in climate patterns. Agricultural insurance is gaining an increasing role as a risk management tool. Given this, the insurance sector has a significant emphasis on identifying, gathering and aggregating historical and current regional and localised data, which could be sourced from remote sensing and earth observation (EO) datasets.

To find out more about the needs and challenges of the agro-insurance’s sector and how these might be addressed with current and future EO capabilities, the ESA Earth Observation Best Practice for Agro-Insurance (EO4I) project brings together the EO and agro-insurance sector. The latter is represented by a champion user group comprised of primary insurers as well as reinsurers. The very close and regular contact with those champion users is an outstanding characteristic of this project.

An analysis of the potential customers’ requirements revealed a list of more than 60 challenges and needs of the sector, such as the assistance in damage assessments, identification of potential risk effects, estimation of affected area and the extent of damage, or monitoring the crop development throughout the season. These challenges were translated into geo-information requirements for a better analysis of currently available EO capabilities. As could be seen so far, business processes of insurance industry can be supported by numerous remote sensing products and services.

Nevertheless, there is a major gap between the perceived potential and the actual application of available EO capabilities by the agro-insurance sector. The bottleneck is the lack of awareness, understanding and trust in the EO products and services for the agro-insurance sector on both sides, the insurers and their customers. The remote sensing community also often focusses on the possibilities and appropriateness of certain techniques, without considering the impact on the customer value, the productivity and profitability of the industry.

Therefore, EO methods, products and services need to be adaptable to the agro-insurance’s business needs and fit into their daily workflows. The project now builds on the results of this initial requirements analysis to connect EO products with insurance solutions to go from best practice to practice. To demonstrate the potential of EO and cutting-edge technology for the agricultural insurance sector, customised use cases to support loss assessment and monitoring based on artificial intelligence will be developed for selected areas and tested with the available in-situ data.
Vegetation dynamics drive the evolution of soil aggregate stability during the first 14,000 years of soil development in the Swiss alps
Authors: Greinwald Konrad , Gebauer Tobias , Treuter Ludwig , Kolodziej Victoria , Musso Alessandra , Maier Fabian , Lustenberger Florian , Scherer-Lorenzen Michael
Published: March 2021

Aims:

The stability of hillslopes is an essential ecosystem service, especially in alpine regions with soils prone to erosion. One key variable controlling hillslope stability is soil aggregate stability. However, there is comparatively little knowledge about how vegetation dynamics affect soil aggregate stability during landscape evolution.

Methods:

We quantified soil aggregate stability by determining the Aggregate Stability Coefficient (ASC), which was developed for stone-rich soils. To reveal how hillslope aging and corresponding changes in vegetation affect the evolution of ASC, we measured plant cover, diversity, and root traits along two chronosequences in the Swiss Alps.

Results:

We found a significant positive effect of vegetation cover and diversity on ASC that was mediated via root traits. These relationships, however, developed in a time-depended manner: At young terrain ages, above- and belowground vegetation characteristics had a stronger effect on aggregate stability than species diversity, whereas these relationships were weaker at older stages.

Conclusions:

Our findings highlight the importance of vegetation dynamics for the evolution of aggregate stability and enhance our understanding of processes linked to hillslope stabilization, which is a key priority to avoid further soil degradation and connected risks to human safety in alpine areas.
Bias-correction of Surface Wind over Reunion and Mauritius Islands using CORDEX Regional Climate Model: RegCM4.7
Authors: Singh Swati , Tang Chao , Morel Béatrice
Published: March 2021

The world needs energy for its social and economic development. In the growing population and industrialization, there is an increasing demand for energy worldwide. The fossil fuel resources are still major resources for fulfilling this energy demand though they are responsible for the increased GHG emissions. Renewable energy is an alternative and greener approach towards meeting increasing energy demand. The wind energy is one of the most prominent resources of greener and renewable energy. The islands of Mauritius and Reunion in the southwest Indian Ocean are blessed with wind resources. The wind energy can be used to meet the demand of energy requirement of these two islands by increasing the number of wind turbines. However, energy generation with wind turbines is sensitive to the variability in the surface wind due to climate variability. The surface wind data available is sparse due to limited ground-based observation. The data quality is also affected by instrumental errors, and data is available only for past and present. Regional Climate Models (RCMs) are the main source of climate information for the present and the future. However, simulations from RCMs deal with biases from various sources and therefore need to bias-corrected. Here we use a transfer function based on the method proposed by Li et al. (2010) for the bias-correction of surface wind over Reunion and Mauritius islands. For this purpose, RegCM4.7 RCM from CORDEX AFR22 domain has been chosen for the time period of 1981-2004. The data is interpolated at 9 km resolution and bias-corrected with respect to surface wind data obtained from ERA5 land reanalysis data. The bias-corrected results are validated with the ERA5 land reanalysis data set.
Thin current sheets of sub-ion scales observed in planetary magnetotails
Authors: Grigorenko Elena , Leonenko Makar , Zelenyi Lev , Malova Helmi , Popov Victor
Published: March 2021

Current sheets (CSs) play a crucial role in the storage and conversion of magnetic energy in planetary magnetotails. Spacecraft observations in the terrestrial magnetotail reported that the CS thinning and intensification can result in formation of multiscale current structure in which a very thin and intense current layer at the center of the CS is embedded into a thicker sheet. To describe such CSs fully kinetic description taking into account all peculiarities of non-adiabatic particle dynamics is required. Kinetic description brings kinetic scales to the CS models. Ion scales are controlled by thermal ion Larmor radius, while scales of sub-ion embedded CS are controlled by the topology of magnetic field lines until the electron motion is magnetized by a small component of the magnetic field existing in a very center of the CS. MMS observations in the Earth magnetotail as well as MAVEN observations in the Martian magnetotail with high time resolution revealed the formation of similar multiscale structure of the cross-tail CS in spite of very different local plasma characteristics. We revealed that the typical half‐thickness of the embedded Super Thin Current Sheet (STCSs) observed at the center of the CS in the magnetotails of both planets is much less than the gyroradius of thermal protons. The formation of STCS does not depend on ion composition, density and temperature,  but it is controlled by the small value of the normal component of the magnetic ﬁeld at the neutral plane. Our analysis showed that there is a good agreement between the spatial scaling of multiscale CSs observed in both magnetotails and the scaling predicted by the quasi-adiabatic model of thin anisotropic CS taking into account the coupling between ion and electron currents. Thus, in spite of the signiﬁcant differences in the CS formation, ion composition, and plasma characteristics in the Earth’s and Martian magnetotails, similar kinetic features are observed in the CS structures in the magnetotails of both planets. This phenomenon can be explained by the universal principles of nature. The CS once has been formed, then it should be self-consistently supported by the internal coupling of the total current carried by particles in the CS and its magnetic conﬁguration, and as soon as the system achieved the quasi-equilibrium state, it “forgets” the mechanisms of its formation, and its following existence is ruled by the general principles of plasma kinetic described by Vlasov–Maxwell equations.

This work is supported by the Russian Science Foundation grant № 20-42-04418
Advancing community-led research into the climate of the Common Era
Authors: Eggleston Sarah S. , Phipps Steven , Bothe Oliver , McGregor Helen V. , Martrat Belen , Linderholm Hans , Konecky Bronwen , Abram Nerilie , St. George Scott
Published: March 2021

The past two thousand years is a key interval for climate science. This period encompasses both the era of human-induced global warming and a much longer interval when changes in Earth’s climate were governed principally by natural drivers and unforced variability. Since 2009, the Past Global Changes (PAGES) 2k Network has brought together hundreds of scientists from around the world to reconstruct and understand the climate of the Common Era using open and collaborative approaches to palaeoclimate science, including virtual meetings. The third phase of the network will end in December 2021. Here we highlight some key outputs of PAGES 2k and present the major themes and scientific questions emerging from recent surveys of the community. We explore how these might boost a new phase of PAGES 2k or a successor project(s). This year we will further reach out to the community through Town Hall consultations, vEGU and other meetings, and a PAGES 2k global webinar series. The aim of these activities is to foster development of post-2021 community-led PAGES initiatives that connect past and present climate.
Multi-year prediction of drought and heat stress to support decision making in the wheat sector
Authors: Solaraju-Murali Balakrishnan , Gonzalez-Reviriego Nube , Caron Louis-Philippe , Ceglar Andrej , Toreti Andrea , Zampieri Matteo , Doblas-Reyes Francisco Javier
Published: March 2021

Unfavorable and extreme climate events such as drought and heat stress affect wheat production and food security globally. Predicting such climate events in the next decade is of great interest for decision-makers, as this time horizon coincides with the strategic planning of many stakeholders in the wheat sector. To address this, we assess the forecast quality in predicting the evolution of drought and heat stress conditions using two proxy user-oriented drought and heat stress indicators: Standardized Potential Evapotranspiration Index (SPEI6) and Heat Magnitude Day Index (HMDI3) on a multi-annual timescale (forecast years 1 to 5). In particular, we present the probabilistic skill and reliability of decadal forecast to predict these indices for the months preceding wheat harvest on a global spatial scale. We use decadal forecasts from the Community Earth System Model Decadal Prediction Large Ensemble (CESM-DPLE), which contributes to the Decadal Climate Prediction Project (DCPP) of CMIP6. Following this, we demonstrate the potential applicability of these forecasts to enhance the adaptation and mitigation activities in the wheat sector by presenting the forecast of multi-year averaged SPEI6 and HMDI3 based on categorical events for the period 2016-2020 along with the corresponding observational values.
Long-term groundwater database and assessment for the Mediterranean region
Authors: Chavez Garcia Silva Rafael , Reinecke Robert , Varouchakis Emmanouil , Gómez-Hernández Jaime , Rode Michael , Jomaa Seifeddine
Published: March 2021

The Mediterranean region faces water security challenges with increasing water demand and climate change effects. Groundwater has become a key resource for water supply and economic development in the last decades, however, its budget remains poorly understood. The distribution of piezometric data in the Mediterranean has a very contrasting distribution. A large portion of them is not centralized and openly accessible, resulting in lack of detailed assessment of groundwater trends and their controlling factors at the regional Mediterranean scale. The objectives of this work are: i) the creation of a long-term and, possibly, the most comprehensive database for groundwater dynamics in the Mediterranean region, ii) the identification of trends and clusters on groundwater levels, and iii) the identification of the relationship between trends and climatic and hydrogeological drivers.

Over 10,000 time series of groundwater level have been collected from national and regional authorities and the literature. The data come from eight countries in the Mediterranean region and have been post-processed into a common format. A search for seasonal patterns and long-term trends is performed then clustered accordingly. Furthermore, the influence of controlling factors such as precipitation and hydrogeology on the groundwater dynamics and trends are assessed. Significant groundwater level changes have been identified at a regional scale and used to provide insight into groundwater level change drivers’ in the Mediterranean region. The database is the result of a unique joint effort between regional groundwater experts to collect groundwater status information in the Mediterranean region and will serve as the foundation for future research on the influence of anthropogenic drivers and the prediction of groundwater depletion hotspots.

This work was developed under the scope of the InTheMED project. InTheMED is part of the PRIMA programme supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 1923.
Skill assessment of post-processing methods for ECMWF SEAS5 seasonal forecasts over Europe
Authors: Crespi Alice , Petitta Marcello , Grigis Lucas , Marson Paola , Soubeyroux Jean-Michel , Viel Christian
Published: March 2021

Seasonal forecasts provide information on climate conditions several months ahead and therefore they could represent a valuable support for decision making, warning systems as well as for the optimization of industry and energy sectors. However, forecast systems can be affected by systematic biases and have horizontal resolutions which are typically coarser than the spatial scales of the practical applications. For this reason, the reliability of forecasts needs to be carefully assessed before applying and interpreting them for specific applications. In addition, the use of post-processing approaches is recommended in order to improve the representativeness of the large-scale predictions of regional and local climate conditions. The development and evaluation downscaling and bias-correction procedures aiming at improving the skills of the forecasts and the quality of derived climate services is currently an open research field. In this context, we evaluated the skills of ECMWF SEAS5 forecasts of monthly mean temperature, total precipitation and wind speed over Europe and we assessed the skill improvements of calibrated predictions.

For the calibration, we combined a bilinear interpolation and a quantile mapping approach to obtain corrected monthly forecasts on a 0.25°x0.25° grid from the original 1°x1° values. The forecasts were corrected against the reference ERA5 reanalysis over the hindcast period 1993–2016. The processed forecasts were compared over the same domain and period with another calibrated set of ECMWF SEAS5 forecasts obtained by the ADAMONT statistical method.

The skill assessment was performed by means of both deterministic and probabilistic verification metrics evaluated over seasonal forecasted aggregations for the first lead time. Greater skills of the forecast systems in Europe were generally observed in spring and summer, especially for temperature, with a spatial distribution varying with the seasons. The calibration was proved to effectively correct the model biases for all variables, however the metrics not accounting for bias did not show significant improvements in most cases, and in some areas and seasons even small degradations in skills were observed.

The presented study supported the activities of the H2020 European project SECLI-FIRM on the improvement of the seasonal forecast applicability for energy production, management and assessment.
Estimating mesophyll and biochemical limitations to carbon assimilation of potato crop during drought
Authors: Beauclaire Quentin , Longdoz Bernard
Published: March 2021

Understanding how plant crops respond to drought is essential for both improving photosynthesis modelling and predicting the impacts of climate change on agricultural production. Over the past years, researches have focused on identifying the stomatal processes that restrict the net photosynthetic rate and quantifying the importance and how different factors limit it. However, the constraints to photosynthesis coming from perturbation in the mechanisms taking place from sub-stomatal cavities to carboxylation sites in chloroplasts are not yet fully understood especially in plant crops. The aim of our study was to investigate the impact of drought on the light-limited photosynthesis rate for potato (Solanum Tubersosum) by measuring the photosynthesis limitations and partitioning them between stomatal, mesophyll and biochemical constrains during a field-experiment that took place in Wallonia during the summer 2020. Gas-exchange and fluorescence techniques were used to quantify mesophyll conductance (gm), stomatal conductance (gs), Rubisco carboxylation rate (Vcmax) and electron transport rate (Jmax) in response to low soil water content during the tuber development stage. We obtained a clear reduction of the leaf assimilation and performed a limitation analysis identifying which factor contributed the most to the light-saturated photosynthetic rate (An) decrease. During the one-month drought treatment, An, gm, Jmax and Vcmax significantly decreased when the relative extractable water (REW) passed below a threshold ranging from 0.5 to 0.7 . On the opposite, g1, the slope of the gs dependence on environmental factors, remained constant. When soil water was not limiting, most of the light-saturated photosynthetic rate variation was explained by VPD while mesophyll and biochemical influence progressively increased when soil water content declined. At the maximum drought intensity, gm and Vcmax reduction explained respectively 40 % and 30% of the light-saturated photosynthetic rate decrease. The coexistence of aerial drought (high VPD) accounted only for 3% of the total limitation. This highlights the importance of mesophyll and biochemical limitations on potato photosynthesis and development.
Sampling theorem of satellite gravimetry from the perspective of the Bender configuration
Authors: Yadav Anshul , Devaraju Balaji , Weigelt Matthias , Sneeuw Nico
Published: March 2021

Satellites in different orbital configurations acquire gravity signals differently. Thus, a difference in admissible spectral coefficients can be expected when the orbital geometry changes. A simple illustration of this phenomenon is seen in the Bender configuration of two GRACE-like satellite pairs - polar and inclined. In the Bender configuration, the polar pair covers the entire globe. In contrast, the inclined pair does not cover the higher latitudes leaving a local discontinuity around the poles in the acquired signal (better known as the Polar Gap problem). Similarly, due to its north-south orientation, the polar pair can capture the features that are predominantly oriented in the east-west direction. Trying to understand better the relationship between satellite geometry and signal acquisition led us to take our first steps in the direction of a unified sampling theory in satellite gravimetry. To this end, we employed the concepts behind the rotation of spherical harmonic coefficients built upon Inclination functions to express the geopotential functionals. Our work utilizes the Lomb-Scargle Periodogram based approach to ascertain limiting frequencies from the systemic quasi-regular sampling net formed on the satellite torus contrary to interpolation and FFT based techniques used in earlier such research endeavors. Through our work, we aim at improving our understanding of how the transformation of the geopotential occurs from the global to the spectral domain. We hope that this will help design future satellite missions with geometries best suited for their objective based on the precise determination of essential spectral coefficients.
Modelling ground deformation in Tenerife (Canary Islands) during 2003-2010
Authors: Przeor Monika , D'Auria Luca , Pepe Susi , Tizzani Pietro
Published: March 2021

Tenerife is the biggest island of the Canaries and one of the most active from the volcanological point of view. The island is geologically complex, and its main volcano-tectonic features are three volcanic rifts and the composite volcanic complex of Teide-Las Cañadas. The latter is located in the central part of the island at the intersection of Tenerife principal rifts. Teide volcano, with its 3718 m of elevation constitutes the most prominent topographical feature of the island. Being a densely populated active volcanic island, Tenerife is characterised by a high volcanic risk. For this reason, the island requires an advanced and efficient volcano monitoring system. Among the geophysical parameters that could be useful to forecast an oncoming volcanic eruption, the ground deformation is relevant for detecting the approach of magma to the surface.

This study aim is to analyse the ground deformation in the surroundings of the Teide-Las Cañadas complex.  For this purpose, we studied the ground deformation of Tenerife by using a set of Synthetic Aperture Radar (SAR) images acquired between 2003 and 2010 by the ENVISAT ASAR sensor and processed through a DInSAR-SBAS technique. The DInSAR SBAS time series revealed a ground deformation in the central part of the island, coinciding with the Teide volcano. A similar deformation was already evidenced by Fernández et al. (2009) from 2004 to 2005.

We investigated the source of this ground deformation by applying the statistical tool of Independent Component Analysis (ICA) to the dataset. ICA allowed separating the spatial patterns of deformation into four components. We attributed three of them to an actual ground deformation, while the fourth seems to be only related to the noise component of data. The first component (ICA1) displays a spatial pattern localised in Teide volcano neighbourhoods and consists of a ground uplift of few centimetres. The deformation associated with this component starts in 2005 and persists along the rest of the time series. The second component (ICA2) of the ground deformation is localised in the South/South-West part of Las Cañadas rim while the third component (ICA3) is localised to the East of Teide volcano. We performed inverse modelling to analyse the source of the ground deformation related to ICA1 to retrieve the location, the geometry and the temporal evolution of this source. The inversion was based on analytical models of ground deformation as well as on Finite-Element-Modelling. The result showed that the ground deformation is associated with a shallow sill-like structure, located beneath Teide volcano, possibly reflecting a hydrothermal reservoir. The knowledge of this source geometry could be of significant interest to better understand ground deformation data of possible future volcanic crisis. 
Reconstructing the surface temperature fields of the Last Glacial Maximum and mid-Pliocene Warm Period using climate models and data.
Authors: Annan James , Hargreaves Julia , Mauritsen Thorsten
Published: March 2021

We present new reconstructions of global climatological temperature fields for the Last Glacial Maximum and the mid-Pliocene Warm Period.

The method is based on an Ensemble Kalman Smoother which combines globally complete modelled temperature fields, with sparse proxy-based estimates of local temperature anomalies. This ensures spatially coherent fields which respect physical principles and which are also tied closely to observational estimates. 

For the Last Glacial Maximum, we use the full set of PMIP2/3/4 model simulations, and we combine this with a wide range of proxy-based SST and SAT estimates of local temperature to ensure the best possible global coverage. Our reconstruction has a global mean surface air temperature anomaly of -5.3 +- 0.9C relative to the pre-industrial climate, and thus lies roughly half-way between the estimates of Annan and Hargreaves (2013) and Tierney et al (2020). We examine the reasons for these differences and discuss their implications.

For the mid-Pliocene Warm Period, we use the PlioMIP 1 and 2 model simulations and the PRISM proxy estimates for the 3.2 Ma time slice. These data are considerably more sparse and uncertain than for the LGM and our reconstruction is correspondingly more uncertain. We obtain an estimate of 5.6 +- 1.6C which is considerably warmer than most previous estimates, suggesting a significant discrepancy between the models and the data. We investigate the reasons for this and discuss the implications.
The potential use of sedimentary pyrogenic biomarkers to quantitatively reconstruct wildfires occurrence and extension
Authors: Raja Maria , Rivas Pedro , Muñoa Gorka , Moreu Carles , Penalva Nuria , Davtian Nina , Villanueva Joan , Rosell-Melé Antoni
Published: March 2021

We have developed and applied new analytical methodologies to study the drivers of the spatial distribution of pyrogenic biomarkers throughout the Iberian Peninsula. The goal of the study is to develop a multiproxy pyrogenic biomarker approach to quantitatively reconstruct the paleo-occurrence and extension of biomass wildfires from sediments. For this purpose, we have compiled an extensive collection of lacustrine sediments throughout Spain. The sample suite is representative of a wide range of climates and ecosystems. We have quantified the abundance of different types of pyrogenic biomarkers such as BPCAs (benzene polycarboxylic acids derived from the chemical oxydation of pyrogenic carbon), MAS (monosaccharide anhydrides, namely levoglucosan) and PAHs (polyaromatic hydrocarbons namely with 4 or more rings). The data obtained, as concentrations or ratios, has been mapped and compared to the documented occurrence and extension of wildfires in Spain over the last 5 decades. Specifically, we have calculated the burned area within different radius around the lake, and correlated them against the biomarker data. 

The regional distribution of fires in Spain is the primary driver of the spatial distribution of pyrogenic biomarkers in lakes sediments. Thus, the sedimentary concentration of pyrogenic biomarkers, generally, correlates with the area of burned forest land within a radius of 10-20km. Work is still under way to decipher the meaning between the correlations of different types of pyrogenic biomarkers, and the relation between biomarker ratios and fire regimes and vegetation types. Our study shows that pyrogenic biomarkers in lakes can be used as paleoproxies to study regional fires, as opposed to those occurring at larger spatial scales. It remains to be seen, how our findings  from Spanish lakes can be extrapolated  to other continental regions.  Nonetheless, our study validates their use to quantify the area of forest burned in the region surrounding the lake, in addition to the frequency of fires in the past.
From the last interglacial to the future – new insights from modeling the last glacial-interglacial cycle in PalMod
Authors: Fieg Kerstin , Latif Mojib , Schulz Michael , Ilyina Tatjana
Published: March 2021

We present new insights from the project PalMod, which started in 2016 and is envisioned to run for a decade. The modelling initiative PalMod aims at filling the long-standing scientific gaps in our understanding of the dynamics and variability of the climate system during the last glacial-interglacial cycle. One of the grand challenges in this context is to quantify the processes that determine the spectrum of climate variability on timescales that range from seasons to millennia. Climatic processes are intimately coupled across these timescales. Understanding variability at any one timescale requires understanding of the whole spectrum. If we could successfully simulate the spectrum of climate variability during the last glacial cycle in Earth system models, would this enable us to more reliably assess the future climate change? Such simulations are necessary to deduce, for example, if a regime shift in climate variability could occur during the next centuries and millennia in response to global warming. PalMod is specifically designed to enhance our understanding of the Earth system dynamics and its variability on timescales up to the multimillennial with complex Earth System Models.

The following major goals were achieved up to now:

Full coupling of atmosphere, ocean and ice-sheet models, enabling investigation of Heinrich Events and bi-stability of the AMOC, and millennial-scale transient climate-ice sheet simulations.

Implementation of a coupled ocean and land biogeochemistry enabling simulations with prognostic atmospheric CO2 concentrations and including improved representation of methane (CH4) in transient deglaciation runs.

Systematic comparison of newly compiled proxy data with model simulations.

The major goal for the next two years is to set up the fully coupled physical-biogeochemical model which will be tested for three time periods: deglaciation, glacial inception and Marine Isotope Stage 3 (MIS3). This fully coupled model will be eventually used to simulate the complete glacial cycle and project the climate over the next few millennia.
Oligocene sea-surface temperature gradients in the Southern Ocean related to Tasmanian Gateway widening: New TEX86 paleothermometry, dinoflagellate cyst data and climate model comparisons
Authors: Hoem Frida , Hou Suning , Huber Matthew , Sangiorgi Francesca , Brinkhuis Henk , Bijl Peter
Published: March 2021

The opening of the Tasmanian Gateway during the Eocene and further deepening in the Oligocene is hypothesized to have reorganized ocean currents, preconditioning the Antarctic Circumpolar Current (ACC) to evolve into place. However, fundamental questions still remain on the past Southern Ocean structure. We here present reconstructions of latitudinal temperature gradients and the position of ocean frontal systems in the Australian sector of the Southern Ocean during the Oligocene. We generated new sea surface temperature (SST) and dinoflagellate cyst data from the West Tasman margin, ODP Site 1168. We compare these with other records around the Tasmanian Gateway, and with climate model simulations to analyze the paleoceanographic evolution during the Oligocene. The novel organic biomarker TEX86- SSTs from ODP Site 1168, range between 19.6 – 27.9°C (± 5.2°C, using the linear calibration by Kim et al., 2010), supported by temperate and open ocean dinoflagellate cyst assemblages. The data compilation, including existing TEX86-based SSTs from ODP Site 1172 in the Southwest Pacific Ocean, DSDP Site 274 offshore Cape Adare, DSDP Site 269 and IODP Site U1356 offshore the Wilkes Land Margin and terrestrial temperature proxy records from the Cape Roberts Project (CRP) on the Ross Sea continental shelf, show synchronous variability in temperature evolution between Antarctic and Australian sectors of the Southern Ocean. The SST gradients are around 10°C latitudinally across the Tasmanian Gateway throughout the early Oligocene, and increasing in the Late Oligocene. This increase can be explained by polar amplification/cooling, tectonic drift, strengthening of atmospheric currents and ocean currents. We suggest that the progressive cooling of Antarctica and the absence of mid-latitude cooling strengthened the westerly winds, which in turn could drive an intensification of the ACC and strengthening of Southern Ocean frontal systems.
Graphical resolution of  Humic structures
Authors: Scrano Laura , Mottola Francesca , Stefanelli Cosimo Mario , Lelario Filomena , Bianco Giuliana , Bufo Sabino Aurelio
Published: March 2021

Advanced techniques have been recently used to obtain information on Natural Organic Matter (NOM). However, the current knowledge of the chemical structure of humic substances (HS) is still incomplete. These substances appear to be too complex mixtures of charged organic molecules, and their characterization remains one of the most stimulating challenges in modern environmental science. Knowledge of the chemical composition of NOM is of great importance for the definition of soil and water properties because it has a significant impact on the understanding of numerous molecular and global-scale processes.
This study aims to apply two-dimensional graphical methods to resolve homologous series in mass spectra of humic extracts (Suwannee River, Nordic Aquatic and Soil) obtained using FT-ICR / MS (Thermo LTQ FT, 7 Tesla) in negative ionization mode. Electrospray ionization (ESI) coupled with ultra-high resolution mass spectrometry offered by Fourier transformed ion cyclotron resonance (FT-ICR / MS) has emerged with great promise as it can provide an overview of the NOM composition and details on a molecular scale. NOM's very high-resolution FT-ICR spectra can be extremely complicated. These spectra usually contain many peaks at each nominal mass and thousands of peaks across the entire spectrum. Each peak can represent a chemically distinct compound. This complexity poses an analytical challenge to the study of spectra for structural interpretation. Two-dimensional graphing methods, such as Kendrick and van Krevelen graphs, have been successfully applied to very high-resolution mass spectra, allowing peaks to be sorted into complicated spectra from their homologous relatives across the mass range.
In van Krevelen plots, ionic signals corresponding to structural similarities between homologous series of compounds involved in the loss or gain of functional groups are found on straight lines. We identified many interesting homologous regions and compared the three humic standards with each other. Finally, we recognized the structural relationships of the homologous series obtained through Kendrick graphs.
The results showed homologous series in the Suwannee River and Nordic Aquatic samples compared to the soil-extracted samples (soil-FA and soil-HA). In particular, homologous series signals related to methylation/demethylation, hydrogenation/dehydrogenation, hydration/dehydration, and oxidation/reduction processes were lower in the soil-FA van Krevelen diagrams. On the contrary, the differences were not so evident in all the homologous series for the soil-HA samples.
Geomagnetic activity effects on CO2‐driven trend in the thermosphere and ionosphere:  ideal model experiments with GAIA
Authors: Liu Huixin , Tao Chihiro , Jin Hidekatsu
Published: March 2021

We examine impacts of geomagnetic activity on CO2-driven trend in the Ionosphere and Thermosphere (IT) using the GAIA whole atmosphere model. The model reveals three salient features. (1) Geomagnetic activities usually weakens the CO2-driven trend at a fixed altitude. Among the IT parameters analyzed, the thermosphere mass density is the most robust indicator for CO2 cooling effect even with geomagnetic activity influences. (2) Geomagnetic activities can either strengthen or weaken the CO2-driven trend in hmF2 and NmF2, depending on local time and latitudes. This renders the widely used linear fitting methods invalid for removing geomagnetic effects from observations. (3) An interdependency exists between the efficiency of CO2 forcing and geomagnetic forcing, with the former enhances at lower geomagnetic activity level, while the latter enhances at higher CO2 concentration. This could imply that the CO2-driven trend would accelerate in periods of declining geomagnetic activity, while magnetic storms may have larger space weather impacts in the future with increasing CO2. These findings provide a preliminary model framework to understand interactions between the CO2 forcing from below and the geomagnetic forcing from above.
Towards pluvial flooding hazard assessment in an urban environment
Authors: Seleem Omar , Heistermann Maik , Bronstert Axel
Published: March 2021

Urban pluvial floods are considered as a ubiquitous hazard. The increase in intensity and frequency of extreme rainfall events, combined with high population density makes urban areas vulnerable to pluvial flooding. Pluvial floods could occur anywhere depending on the existence of minimal areas for surface runoff generation and concentration. Detailed hydrologic and hydrodynamic simulations are computationally expensive and resource-intensive. This study applies two computationally inexpensive approaches to identify risk areas for pluvial flooding. One approach uses common GIS operations to detect flood-prone depressions from a high-resolution 1m x 1m Digital Elevation Model (DEM), to identify contributing catchments, and to represent runoff concentration by a fill-spill-merge approach. The second approach employs GIS to identify pluvial flood-prone hotspots in terms of the topographic wetness index (TWI).  Based on the exceedance of a TWI threshold, flood-prone areas are identified using a maximum likelihood method. The threshold is estimated by comparing the TWI to inundation profiles from a two-dimensional (2D) hydrodynamic model (TELEMAC 2D), calculated for various rainfall depths within a given spatial window. The two approaches are applied to two flooding hotspots in Berlin, which have been repeatedly subject to pluvial flooding in the last decades and the outputs are compared against the detailed output from TELEMAC 2D. 
Results on an Inter-model Comparison on Secondary Aerosol Formation
Authors: Tan Jiani , Fu Joshua , Carmichael Gregory , Su Hang , Cheng Yafang
Published: March 2021

This study aims at comparing the gas-to-particle conversion mechanisms adopted by regional chemical transport models (CTMs). We use the results from twelve regional CTMs from the third phase of the Model Inter-Comparison Study for Asia (MICS-Asia III). The simulations are conducted over East Asia for the whole year of 2010. The models used are WRF-CMAQ (version 4.7.1 and v5.0.2), WRF-Chem (v3.6.1 and v3.7.1), GEOS-Chem, NHM-Chem, NAQPMS and NU-WRF. Measurements from 54 EANET sites, 86 sites of the Air Pollution Indices (API) and 35 local sites, remote sensing products from AERONET and satellite data from MODIS are used to evaluate model performance on PM10, PM2.5 and its components and aerosol optical depth (AOD). To investigate the inter-model differences in secondary aerosol formation, we compare the Sulfur Oxidation Ratio (SOR) and Nitrogen Oxidation Ratio (NOR) values by different models with observations at the EANET sites. The preliminary results show that the inter-model differences in the oxidation ratio (50%) are almost of the same magnitude as those in simulating the concentrations of particles. The results suggest large uncertainties in the gas-particle conversion process in modelling secondary aerosol formation.
Experiences of a nature-based urban development on the example of a Hungarian city
Authors: Katona Máté , Horváth Adrienn
Published: March 2021

Kaposvár is a developing middle-size city in the middle of South-western Hungary surrounded by mountains and forested areas. Due to its location and natural surroundings, the city strives to achieve close-to-nature urban development. Sustainable urban management, increasing green space, promoting carbon neutrality, adaptation to the challenges of climate change, reducing emissions are the main aims of the development. For support, city-wide investigations began last year to make further suggestions for future direction based on measurements and experience. A foundational survey was conducted to characterize the conditions of urban soils and urban plantations; thus, it would have a proper space in the city’s climate strategy and settlement development concept in the future. Soil properties (artefacts, pH, texture, CaCO3) and trace metal concentrations (Pb, Cu, Zn, Ni, Cr, Sn, Cd, Co) were measured as well. Compared to the actual condition of the natural environment, the soil-changing effect of the city became visible. For changed soil conditions, trees should be chosen that are well adapted to this changing environment. The city is currently afforesting its area; however, it wants to increase the number of trees planted in the future. This is especially justified in areas where there are many overgrown, old, diseased trees in its hundred-year-old parks and tree lines. Choosing the right tree species is not only an aesthetic consideration, but it can also affect the condition of the soils in the environment. We also considered the effects of heavy metals pollution on vegetation important, so we took samples from the trees leaves in many parts of the city and measured the total metal content they absorbed. To comparison, the nearby soil test points showed a correlation between leaves pollution levels in several cases. Based on the results, the heavy metal uptake capacity of the different tree species became comparable. It can be used effectively in the selection of tree species for future afforestation, so that afforestation can also play a role in soil protection and city climate maintenance in the future.
The role of oceanic internal instabilities on the Great Whirl interannual variability 
Authors: Sadhvi Kwatra , Suresh Iyyappan , Izumo Takeshi , Vialard Jérôme , Lengaigne Matthieu , Penduff Thierry , Molines Jean-Marc
Published: March 2021

The Great Whirl (GW) is a quasi-permanent anticyclonic eddy that appears every summer monsoon in the western Arabian Sea off the horn of Africa. It generally forms in June, peaks in July-August, and dissipates afterward. While the annual cycle of the GW has been previously described, its year-to-year variability has been less explored. Satellite observations reveal that the leading mode of summer interannual sea-level variability in this region is associated with a typically ~100-km northward or southward shift of the GW. This shift is associated with coherent sea surface temperature and surface chlorophyll signals, with warmer SST and reduced marine primary productivity in regions with positive sea level anomalies and vice versa. Eddy-permitting (~25 km) and eddy-resolving (~10 km) ocean general circulation model simulations reproduce the observed pattern reasonably well, even in the absence of interannual variations in the surface forcing. This implies that the GW interannual variability partly arises from oceanic internal instabilities. Ensemble oceanic simulations further reveal that this stochastic oceanic intrinsic variability and the deterministic response to wind forcing each contribute to ~50% of the total GW interannual variability in July-August. The deterministic part appears to be related to the oceanic response  to Somalia alongshore wind stress and offshore wind-stress curl variations during the monsoon onset projecting onto the GW structure, and getting amplified by oceanic instabilities. After August, the stochastic component dominates the GW variability.