bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave induced turbulence effect on oceanic biogeochemistry and study of ocean color response to changing wave climate
Authors: Tensubam Chinglen Meetei , Babanin Alexander V.
Published: March 2021

The role of surface ocean waves becomes substantial in the upper ocean layer mixing. Due to turbulence induced by the surface waves (both broken and unbroken waves), the upper ocean mixing is enhanced, and important upper ocean parameters are affected such as lowering of sea surface temperature (SST), deepening of mixed layer depth (MLD) and most interestingly, the changes in oceanic biogeochemistry. The main objective of this study is to analyze the effect of wave induced turbulence on oceanic biogeochemistry such as the supply and distribution of nutrients to tiny plants in the ocean called phytoplanktons, and how it affects their concentrations. Marine phytoplanktons formed the basis of marine ecosystem which accounts for about 45 percent of global net primary productivity and play an important part in global carbon cycle. The population of phytoplanktons depends mainly on nutrients (both micro and macro), availability of sunlight and grazing organisms. For this study, we use global coupled ocean-sea ice model ACCESS-OM2 with biogeochemical module called WOMBAT to estimate the effect of wave induced turbulence and study the difference between ‘with waves’ and ‘without waves’ effect on oceanic biogeochemistry. The same effect of wave induced turbulence on oceanic biogeochemistry are also studied by incorporating the change in wave climate such as increase in significant wave height and wind speed. From the investigation of merged satellite ocean color data from ESA’s GlobColour project for the period of 23 years between 1997 and 2019, it was found that chlorophyll-a (Chl-a, an index of phytoplankton biomass) concentration showed increasing trend of 0.015 mg/m3 globally and 0.062 mg/m3 in the Southern Ocean (SO) for the study period with p-value less than 0.01. It was also found that most of the increasing trends are shown spatially in the open ocean and decreasing trend in the coastal regions during the study period.
A satellite perspective on fog and low stratus dissipation over Europe
Authors: Pauli Eva , Cermak Jan , Andersen Hendrik
Published: March 2021

In this study, the dissipation of fog and low stratus (FLS) over Europe is analyzed based on geostationary satellite data using logistic regression. 
The dissipation of FLS is a result of the interaction of complex physical processes and its timing has implications for environmental systems, traffic at land, sea and in the air, as well as for the production of solar energy. However, the timing of FLS dissipation, as well as its relationship to meteorological and land surface conditions has not been investigated quantitatively over a large spatial and temporal scale yet. 
In this study a 10-year FLS dissipation climatology is created using logistic regression. For this, a binary satellite-based FLS mask for each 15-minute interval from 2006-2015 over Europe, by Egli et al. 2017, is used. A logistic regression is applied to identify the dissipation time of each individual fog event from the binary FLS time series. Marked geographic FLS dissipation patterns are apparent, where FLS is found to dissipate earlier in elevated terrains and persist longer in valleys. Furthermore, the influence of different meteorological and land surface conditions on FLS dissipation are investigated.
In the future, the presented approach will be extended to analyze FLS formation and its dependency on meteorological and land surface conditions.
Porosity evolution within the active Alpine Fault zone, New Zealand. Implications for fault zone rheology.
Authors: Kirilova Martina , Toy Virginia , Sauer Katrina , Renard Francois , Gessner Klaus , Wirth Richard , Xiao Xianghui , Matsumura Risa , Prior David , Cappuccio Francesco , Morrison Soltice
Published: March 2021

Feedback between deformation mechanisms, fluid-rock interactions and porosity evolution in fault zone rocks has a crucial impact on their bulk rheology. Porosity formation within mid-crustal fault rocks (typically mylonites) can facilitate fluid flow, formation of mineral and geothermal resources, and can promote strain localization. On the contrary, porosity reduction in rocks from a brittle fault core (typically cataclasites) can cause elevated pore fluid pressures, and consequently influence the recurrence time of earthquakes.

We characterized the porosity distribution within the New Zealand’s Alpine Fault zone in cataclasite samples recovered during the first phase of the Deep Fault Drilling Project and outcropping mylonitic rocks collected at Stoney Creek, New Zealand. Synchrotron X-ray microtomography-derived analyses of open pore spaces show total microscale porosity values in the range of 0.1-0.24% within the cataclasites and up to 0.44% in the mylonites. Synchrotron nanotomography datasets reveal additional 0.03 to 0.19% pore volumes within the mylonites. In all samples, pores are very small, not connected, with mainly non-spherical, elongated, flat shapes and show subtle bipolar orientation. Scanning and transmission electron microscopy reveal the samples’ microstructural organization, where nanoscale pores ornament grain boundaries of the constituent minerals. Pores are mostly associated with (often newly formed) clay minerals in the cataclasite samples, suggesting the orientation of clays controls the shape and orientation of the associated pores. In the mylonitic samples, pores are sub-parallel to the foliation, and often associated with C’-type shear bands, indicating formation during creep cavitation.

Our observations imply that porosity within the Alpine Fault core was reduced due to pressure solution processes and the associated mineral precipitation. Simultaneously propagation of fluids triggered by cavity formation in the ductile regime is likely to cause further mineral precipitation in fluid filled pores within the fault zone. Such precipitation can affect the mechanical behavior of the Alpine Fault by decreasing the already critically low total porosity of the fault core, causing elevated pore fluid pressures, and/or introducing weak mineral phases, and thus lowering the overall fault frictional strength. We conclude that the current state of porosity in the Alpine Fault zone is likely to play a key role in the initiation of the next fault rupture.
A volcanic passive continental margin between the Laptev Sea Shelf and the Eurasia Basin?
Authors: Nikishin Anatoly , Savin Vasily , Cloetingh Sierd , Gaina Carmen , Malyshev Nikolay , Petrov Eugene , Poselov Viktor , Rodina Elizaveta , Startseva Ksenia , Verzhbitsky Vladimir
Published: March 2021

New seismic, magnetic and gravity data of the continental margin of the Laptev Sea shelf indicate: (1) Absence of the Lomonosov-Khatanga transform fault between the Eurasia Basin and Laptev Sea shelf. On a number of new seismic lines we do not observe evidence for transtension or transpressional deformation along this lineament whereas some typical deformation for the continental slopes is recognized. Recent seisimicity is absent along the lineament. (2) The pull-apart Laptev-Gakkel continental basin along the Laptev Sea continental slope is in an orthogonal position to the Gakkel Ridge axial rift. This pull-apart basin was tectonically active during Eocene-Oligocene times. (3) Evidence exists for number possible intrusions just below the rift/postrift (break-up) unconformity (56 Ma) on some seismic lines in the area between the Taimyr Shelf and the continental slope of the Eurasia Basin. Evidence is also found for the existence of possible volcanics just below the break-up unconformity in this area. (4) Intrusions might also be present just below the 56 Ma break-up unconformity recognized on some seismic lines in the area between the Lomonosov Ridge and the continental slope of the Eurasia Basin. Buried volcanoes are likely present as well. These two magmatic provinces are symmetric to each other on both sides of the Eurasia Basin and well expressed on the new magnetic anomaly map.(5) The Eurasia Basin has a conical shape in its Southern near-Laptev domain. Opening of the basin appears to be controlled by propagation of oceanic crust spreading to the south. (6) We assume that the continental margin between the Laptev Sea Shelf and the Eurasian Basin could be a passive volcanic margin. This margin is characterized by a structure that is very similar to the North Atlantic margin of almost the same age. This study was supported by RFBR grant (18-05-70011).
A numerical modelling toolbox for identifying the expression of dome-forming volcanism on exoplanets
Authors: Harnett Claire , Heap Michael , Thomas Mark
Published: March 2021

The presence of volcanism is often anecdotally used to define a “living planet”. Since dome-building volcanism on Earth occurs primarily at plate boundaries, the identification of such domes could inform on exoplanetary development. Lava domes form when extruded magma is too viscous to flow from a vent, and their morphology on Earth varies from flat, pancake lobes to steep, blocky domes. Identification of lava domes on other terrestrial planets in our Solar System indicates that they likely also exist on rocky exoplanets. Here we show, using particle-based modelling, that the diversity of lava dome morphology in our Solar System is dwarfed by the diversity expected for exoplanets. Specifically, the height-to-diameter ratio of a dome decreases as a function of increasing gravity (i.e., planetary mass and radius). For example, lava domes on high-gravity super-Earths will be extremely wide and flat and a volcanic origin may not be immediately apparent. Creating a toolbox to help identify exoplanetary volcanism will allow us to make initial estimations as to the development and habitability of these alien worlds as images become available.
When the trigger of deep convection gets tricky in idealized climate simulations
Authors: Matte Dominic , H. Christensen Jens , Fedderson Henrik , A. Pederson Rasmus , Vedel Henrik , Woetmann Nielsen Niels
Published: March 2021

On the evening on July 2, 2011 a severe cloud burst occurred in the Copenhagen area. During the late afternoon deep moist convection developed over nearby Skåne (the southernmost part of Sweden) in an airstream from east-northeast. In the early evening the DMC passed over Øresund to Copenhagen, where it created a severe flash flood. Between 90 and 135 mm of precipitation in less than 2 hours was recorded ooding cellars, streets, and key roads. The deluge caused 6 billion Danish kroner in damage. Although that such extreme events are rare, the impacts on society is important and should be understood under a warmer climate. Although regional climate models have recently reached the convection permitting resolution, reproducing such events is still challenging.

Several studies suggest that extreme precipitations should increase under a future warmer climate using transient simulation or a pseudo-warming approach. It is still unclear how such event would behave under warmer or colder synoptic conditions. Using a forecast-ensemble method, but keeping a climate perspective, this study assesses the risk rising from such an event under otherwise almost identical, but warmer or colder conditions. With this set-up, we find that the development of the system that resulted in observed downpour exhibit quite a sensitivity to the initial conditions and contrary to a linear thinking, the risk of flooding is decreasing as the climate warms due to the inhibition of the CAPE by the additional lapse-rate anomalies used in this study. We therefore propose that the PGW method should be used with caution and that extreme precipitation events also in transient simulations of future climates need to be studied in detailed to address the limitations to models ability to produce those most extreme and by nature inherently rare events.
Response of the interplanetary hydrogen population to global changes of solar activity: a quantitative analysis based on SOHO/SWAN and SOHO/LASCO-C2 data comparison.
Authors: Koutroumpa Dimitra , Quémerais Eric , Conan Lucile , Lamy Philippe , Ferron Stéphane , Gilardy Hugo
Published: March 2021

For more than two decades the SOHO/SWAN instrument has been monitoring the full-sky hydrogen backscattered Lyman-α emission, and the derived three-dimensional solar wind proton flux. We present a comparison of the time series of the latitude-integrated hydrogen ionization rates (β) derived from the inversion of the SWAN full-sky maps with the integrated coronal electron density derived from the inversion of SOHO/LASCO-C2 white light images. The analysis shows a variable time lag of the SWAN β of a few Carrington rotations, correlated with the solar cycle phase (larger delay during solar maxima compared to minima). This is a direct consequence of the variation of the size of the hydrogen ionization cavity and the time it takes for hydrogen atoms to propagate in the inner heliosphere. This effect should be taken into account in studies of the interstellar neutral populations in interplanetary space.
Retreat of Pine Island Glacier: The impact of El Nino Southern Oscillation events 
Authors: Reed Bradley , Green Mattias , Gudmundsson Hilmar , Jenkins Adrian
Published: March 2021

The Amundsen Sea sector in West Antarctica is undergoing dramatic changes, with thinning ice shelves and accelerating, retreating glaciers. One of the largest and fastest flowing ice streams in the region is Pine Island Glacier (PIG). In recent decades it has retreated over 30 km, experienced a 75% increase in velocity and thinned by more than 100m. However, these changes have not been constant, there have been alternating periods of acceleration and stabilisation since the start of the observational era in the 1970s. This has been attributed to variable ocean conditions, where interannual and decadal changes in the Circumpolar Deep Water layer have been linked to large-scale climate variability. The initial ungrounding and subsequent retreat of PIG from a submarine ridge is believed to have been caused by extreme changes in ocean conditions linked to El Niño Southern Oscillation (ENSO) events during the 1940s and 1970s. However, the exact role that these events have played over the last century is not fully understood.

In this study the ice flow model Úa is used to assess how the retreat of PIG has been impacted by ENSO events. During these events, variations in thermocline depth affect the amount of heat available for basal melting beneath the ice shelf. To represent these changing ocean conditions a melt rate parameterisation based on a 1D plume model is used, which depends on ice shelf geometry, grounding line depth and ambient ocean properties. Results will show if a gradually warming ocean is enough to initiate grounding line retreat or if brief, large changes in temperature are required. Further investigations will determine whether cooler years contributed to a slow down of the ice stream. This work will help us understand and model the response of other glaciers to extreme changes in ocean conditions caused by ENSO events in a warming future.
Trend of stream temperature and its drivers over the past 55 years in a large European River basin
Authors: Seyedhashemi Hanieh , Moatar Florentina , Vidal Jean-Philippe , Thiery Dominique , Monteil Céline , Hendrickx Frédéric
Published: March 2021

Air temperature has been increasing all around the world over the past decades. Owing to its sensitivity to air temperature, it is consequently expected that stream temperature experiences an increase as well. However, due to paucity of long-term stream temperature data, assessments of the magnitude of such trends in relation with landscape and hydrological changes have remained scarce.

The present study used a physically-based thermal model (T-NET: Temperature-NETwork), coupled with a semi-distributed hydrological model (EROS) to reconstruct past daily stream temperatures and discharges at the scale of the Loire River basin in France (105 km2 with 52278 reaches). The ability of both models to reconstruct long-term trends was assessed at 44 gauging stations and 11 stream temperature stations.  

T-NET simulations over the 1963-2017 period show that there has been a significant increasing trend in stream temperatures for at least 70% of reaches in all seasons (median=0.36 °C/decade). Significantly increasing trends are more prominent in spring (Mar-May) and summer (Jun-Aug) with a median increase of 0.37 °C (0.11 to 0.8°C) and 0.42°C (0.14 to 1 °C) per decade, respectively. For 81 % of reaches, annual stream temperature trends are greater than annual air temperature trends (median ratio=1.21; interquartile ranges: 1.06-1.44). Greater increases in stream temperature in spring and summer are found in the south of the basin, mostly in the Massif Central (up to 1°C/decade) where greater increase in air temperature (up to 0.67 °C/decade) and greater decrease in discharge (up to -16%/decade) occur jointly. The increase of stream temperature is also higher in large rivers compared to small rivers where riparian vegetation shading mitigate the increase in temperature. For the majority of reaches, changes in stream temperature, air temperature, and discharge significantly intensified in the late 1980s.

These climate-induced changes in the annual and seasonal stream temperature could help us to explain shifts in the phenology and geographical distribution of cold-water fish especially in the south of the basin where trends are more pronounced.
Overcoming basis risk in agricultural index insurance using crop simulation modeling and satellite crop phenology
Authors: H. Afshar Mehdi , Foster Timothy , Higginbottom Thomas P. , Parkes Ben , Hufkens Koen , Mansabdar Sanjay , Ceballos Francisco , Kramer Berber
Published: March 2021

Extreme weather causes substantial damage to livelihoods of smallholder farmers globally and are projected to become more frequent in the coming decades as a result of climate change. Index insurance can theoretically help farmers to adapt and mitigate the risks posed by extreme weather events, providing a financial safety net in the event of crop damage or harvest failure. However, uptake of index insurance in practice has lagged far behind expectations. A key reason is that many existing index insurance products suffer from high levels of basis risk, where insurance payouts correlate poorly with actual crop losses due to deficiencies in the underlying index relationship, contract structure or data used to trigger insurance payouts to farmers. 

In this study, we analyse to what extent the use of crop simulation models and crop phenology monitoring from satellite remote sensing can reduce basis risk in index insurance. Our approach uses a calibrated biophysical process-based crop model (APSIM) to generate a large synthetic crop yield training dataset in order to overcome lack of detailed in-situ observational yield datasets – a common limitation and source of uncertainty in traditional index insurance product design. We use this synthetic yield dataset to train a simple statistical model of crop yields as a function of meteorological and crop growth conditions that can be quantified using open-access earth observation imagery, radiative transfer models, and gridded weather products. Our approach thus provides a scalable tool for yield estimation in smallholder environments, which leverages multiple complementary sources of data that to date have largely been used in isolation in the design and implementation of index insurance

We apply our yield estimation framework to a case study of rice production in Odisha state in eastern India, an area where agriculture is exposed to significant production risks from monsoonal rainfall variability. Our results demonstrate that yield estimation accuracy improves when using meteorological and crop growth data in combination as predictors, and when accounting for the timing of critical crop development stages using satellite phenological monitoring. Validating against observed yield data from crop cutting experiments, our framework is able to explain around 54% of the variance in rice yields at the village cluster (Gram Panchayat) level that is the key spatial unit for area-yield index insurance products covering millions of smallholder farmers in India. Crucially, our modelling approach significantly outperforms vegetation index-based models that were trained directly on the observed yield data, highlighting the added value obtained from use of crop simulation models in combination with other data sources commonly used in index design.
Constraining the timing of crustal thickening using garnet geochronology – An argument against subduction-driven orogenesis in the Dom Feliciano Belt, Brazil
Authors: Percival Jack , Konopásek Jiří , Anczkiewicz Robert
Published: March 2021

Metamorphic minerals in the Brusque Complex of the northern Dom Feliciano Belt, Brazil, provide new insights into the timing and mode of regional convergence, challenging a long-lived subduction-collision model for orogenesis. The key evidence for subduction is an extensive linear belt of granitic rocks (the Granite Belt) that intruded the length of the hinterland of the Dom Feliciano Belt between ~630─580 Ma, and that is inferred to represent arc magmatism above the subducting Adamastor Ocean prior to continental collision. The study area comprises supracrustal units of a foreland fold-and-thrust belt outcropping along the western edge of the symmetric Kaoko─Dom Feliciano orogenic system. The integrated study of primary metamorphic mineral assemblages and associated deformation fabrics support the interpretation of a fold-and-thrust belt environment, with early tectonic movement top-to-NW away from the hinterland. P─T estimates constrained by garnet compositions indicate peak metamorphic conditions of 540─570°C and 5.5─6.5kbar, in line with typical geothermal gradients associated with orogenic metamorphism. The timing of early garnet growth, and by inference the early stages of crustal thickening in the foreland, is constrained by Lu─Hf garnet geochronology at ~660─650 Ma. The data indicate that the onset of metamorphism and deformation in the orogenic foreland occurred ~20–30 m.y. prior to intrusion of extensive granitic magmatism into the orogenic hinterland. The timing of early orogenic thickening in the foreland precludes the interpretation of the Granite Belt as an arc above a large-scale subduction zone in the lead up to orogenesis. Instead, it is interpreted to represent syn-orogenic magmatism typical for hinterland domains in other ancient and recent orogenic systems.

We appreciate financial support from Diku Norway and CAPES Brazil (project UTF-2018-10004), and from the Czech Science Foundation (project no. 18-24281S). This work was partly supported by the Research Council of Norway through the funding to The Norwegian Research School on Dynamics and Evolution of Earth and Planets, project number 249040/F60.
The SERGHEI model and its core shallow water solver
Authors: Morales-Hernández Mario , Özgen-Xian Ilhan , Caviedes-Voullième Daniel
Published: March 2021

The Simulation Environment for Geomorphology, Hydrodynamics and Ecohydrology in Integrated form (SERGHEI) model framework is a multi-dimensional, multi-domain and multi-physics model framework. It is designed to provide a modelling environment for hydrodynamics, ecohydrology, morphodynamics, and, importantly, interactions and feedbacks among such processes, at different levels of complexity and across spatiotemporal scales. SERGHEI is in essence, a terrestrial landscape simulator based on a hydrodynamics core, designed with an outlook towards Earth System Modelling applications. Consequently, efficient mathematical and numerical formulations, as well as HPC implementations are at its core. SERGHEI intends to enable large scale and high resolution problems, which will allow to acknowledge and simulate emergent behaviours rising from the small-scale interactions and feedbacks between different environmental processes, that often manifest at larger spatiotemporal scales.

At the core of the technical innovation in SERGHEI is its HPC implementation, built from scratch on the Kokkos programming model and C++ library. This approach facilitates portability from personal computers to Tier-0 HPC systems, including GPU-based and heterogeneous systems. This is achieved by relying on Kokkos handling memory models, thread management and computational policies for the required backend programming models. In particular, using Kokkos, SERGHEI can be compiled for multiple CPUs and GPUs using a combination of OpenMP, MPI, and CUDA.

In this contribution, we introduce the SERGHEI model framework, and specially its first operational module for solving shallow water equations (SERGHEI-SWE). This module is designed to be applicable to hydrological, environmental and consequently Earth System Modelling problems, but also to classical engineering problems such as fluvial or urban flood modelling. We also provide a first showcase of the applicability of the SERGHEI-SWE solver to several well-known benchmarks, and the performance of the solver on large-scale hydrological simulation and flooding problems. We also show and discuss the scaling properties of the solver (on several Tier-0 systems)  and sketch out its current and future development.
Toward Self-calibrated SM2RAIN-based rainfall product 
Authors: Filippucci Paolo , Brocca Luca , Tarpanelli Angelica , Massari Christian , Wagner Wolfgang , Saltalippi Carla
Published: March 2021

Reliable and detailed precipitation measurements are fundamental in many hydrological and hydraulic applications. In-situ measurements are the traditional source of this information, but the declining number of stations worldwide, the low spatial representativeness and the problems in data access, limit their relevance. In the last years, satellite products have been used to fill the gap of the ground data.

The estimation of precipitation by satellites can be conceptualized via two different  approaches: the top-down approach, where the rainfall is estimated by exploiting the electromagnetic properties of clouds, and the bottom-up approach, where rainfall is indirectly obtained by exploiting the inversion of the water balance equation once soil moisture observations are observed by satellites. SM2RAIN algorithm [Brocca et al., 2014] belongs to the second methodology and has distinguished itself to provide accurate rainfall estimation, particularly in regions characterized by low density of rainfall gauges; however, the use of SM2RAIN relies upon a calibration dataset which represents  a main limitation for its applicability.

In this study, starting from the kwowledge of Advanced SCATterometer (ASCAT) soil moisture, topography and climatology of each pixel of land surface, a methodology for the application of SM2RAIN without using observed rainfall time series for calibration is proposed. Four parametric relationships dependent from physical descriptors of each pixel are developed by using 1009 points uniformly distributed in Australia, India, Italy and the United States, allowing the estimation of SM2RAIN parameter values- A global validation of the methodology is conducted by comparing the performance of the parametrized product against those of a calibrated SM2RAIN product. The Final Run version of the Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG) is used for the performance assessment, together with triple collocation techniques against gauge-based Global Precipitation Climatology Center (GPCC) product and the Early Run version of IMERG.

The approach was also applied to a high resolution (~1 km) Soil Moisture product over test regions in Italy and Austria obtaining promising results and showing that good quality rainfall estimates at 1 km of spatial resolution can be obtained also without calibration.
Cold-water corals in the Subpolar North Atlantic Ocean exposed to aragonite undersaturation if Paris 2 ºC is not met
Authors: García-Ibáñez Maribel I. , Bates Nicholas R. , Bakker Dorothee C.E. , Fontela Marcos , Velo Antón
Published: March 2021

The uptake of carbon dioxide (CO2) from the atmosphere is changing the ocean’s chemical state. Such changes, commonly known as ocean acidification, include reduction in pH and the carbonate ion concentration ([CO32-]), which in turn lowers oceanic saturation states (Ω) for calcium carbonate (CaCO3) minerals. The Ω values for aragonite (Ωaragonite; one of the main CaCO3 minerals formed by marine calcifying organisms) influence the calcification rate and geographic distribution of cold-water corals (CWCs), important for biodiversity. In this work we use high-quality data of inorganic carbon measurements, collected on thirteen cruises along the same track during 1991–2018, to determine the long-term trends in Ωaragonite in the Irminger and Iceland Basins of the North Atlantic Ocean, providing the first trends of Ωaragonite in the deep waters of these basins. The entire water column of both basins showed significant negative Ωaragonite trends between -0.0015 ± 0.0002 and -0.0061 ± 0.0016 per year. The decrease in Ωaragonite in the intermediate waters, where nearly half of the CWC reefs of the study region are located, caused the Ωaragonite isolines to migrate upwards rapidly at a rate between 6 and 34 m per year. The main driver of the observed decline in Ωaragonite in the Irminger and Iceland Basins was the increase in anthropogenic CO2. But this was partially offset by increases in salinity (in Subpolar Mode Water), enhanced ventilation (in upper Labrador Sea Water) and increases in alkalinity (in classical Labrador Sea Water, cLSW; and overflow waters). We also found that water mass aging reinforced the Ωaragonite decrease in cLSW. Based on the observed Ωaragonite trends, we project that the entire water column of the Irminger and Iceland Basins will likely be undersaturated for aragonite when in equilibrium with an atmospheric mole fraction of CO2 (xCO2) of ~860 ppmv, corresponding to climate model projections for the end of the century based on the highest CO2 emission scenarios. However, intermediate waters will likely be aragonite undersaturated when in equilibrium with an atmospheric xCO2 of ~600 ppmv, an xCO2 level slightly above that corresponding to 2 ºC warming, thus exposing CWCs inhabiting the intermediate waters to undersaturation for aragonite.
Using Machine Learning to investigate Heat Waves and Myocardial Infarctions in Augsburg, Germany
Authors: Marien Lennart , Valizadeh Mahyar , zu Castell Wolfgang , Schneider Alexandra , Wolf Kathrin , Rechid Diana , Bouwer Laurens
Published: March 2021

Myocardial infarctions (MI) are a major cause of death worldwide. In addition to well-known individual risk factors, studies have shown that temperature extremes, such as encountered during heat waves, lead to increases in MI. The relationship between health impacts and climate is complex, depending on a multitude of climatic, environmental, sociodemographic and behavioral factors. Machine Learning (ML) is a powerful tool for investigating complex and unknown relationships between extreme environmental conditions and their adverse impacts that has already been applied to other climate extremes, such as in the prediction of flood damages. By combining heterogeneous health, climatic, environmental and socio-economic datasets, this study is a first step in developing an ML model for predicting past and future MI risk due to heat waves.

Here, we present first results of our ML approach for modelling heat-related health effects in Augsburg based on the KORA MI and environmental data. The basis of our data-driven approach is the KORA cohort study and the MI Registry in the Augsburg region of Bavaria, Germany, comprising detailed information on MI and underlying health conditions. Additionally, weather and climate data, air pollution data (e.g., PM10, PM2.5, nitrous oxides, and ozone), as well as socio-economic data (household income, education) are used for this study. One of the key challenges is to assemble and integrate heterogeneous data from various sources and prepare them for the appropriate spatial scales. We outline major challenges in combining these data and deriving quantitative models from them.

Moreover, we present initial results based on both regression and classification models, discussing model performance for the period between 2000 and 2015, with a focus on two major heat wave events in Germany during 2003 and 2006. Ultimately, this research may be useful in better understanding heat-related MI risks, supporting possible adaptation options in urban areas and in identifying high-risk groups within society.
Antarctic sea ice in global ocean reanalyses
Authors: Selivanova Julia , Iovino Doroteaciro
Published: March 2021

Ocean reanalyses (ORAs) are used extensively in polar research, hence their realism should be assessed regularly. Here the ORAs performance in the Antarctic region is analyzed with specific emphasis on sea ice concentration and thickness. We used four global ocean-sea ice products: C-GLORSv7, FOAM-GLOSEA5v13, GLORYS2v4, and ORAS5, and their ensemble mean GREP (provided by CMEMS) within the 1993 to 2018 period. All ORAs use the NEMO ocean model in a global eddy-permitting configuration (1/4° horizontal resolution and 75 vertical levels) and are forced by the ECMWF ERA-Interim atmospheric reanalysis.

Here we examine the ability of ORAs to reproduce sea ice properties in the Southern Ocean taking into account regional characteristics and sea ice types. Seasonal and interannual variability of sea ice concentration (SIC) and sea ice thickness (SIT) is examined in the hemispheric domain and in five sub-regions for three different sea ice classes: pack ice (SIC ≥ 80%), marginal ice zone (MIZ) (15% ≤ SIC < 80%), and sparse ice (0 < SIC <15%).  Modeled sea ice properties are compared to a set of satellite products: NSIDC CDR, Ifremer/CERSAT, and EUMETSAT OSI-SAF for SIC and Envisat and CryoSat-2 for SIT, together with PIOMAS and GIOMAS reanalyses. We revealed shortcomings of reanalysis systems to be improved in the future representation of Antarctic sea ice. Additionally, we focused on the assessment of the GREP ensemble mean product. We found that for certain metrics GREP minimizes the single errors and outperforms individual members. The evidence from this study implies that GREP can be a feasible product for a number of applications.
Effects of colloidal manure DOM on the transport of antibiotics in calcareous soils
Authors: Tang Xiangyu , Liu Chen , Luo Fanglin , Li Shuhan , Yang Hongwei
Published: March 2021

Colloids in the environment are defined as suspended particles in the size range of 1 nm to 10 microns. Both organic matter and antibiotics leached from animal manures applied to farmland may pose a pollution risk of groundwater. Manure colloids, which are mainly composed of dissolved organic matter (DOM), have been known to play an important role in facilitating transport of various strongly-sorbing contaminants in subsurface environments. Research on co-transport behavior of manure colloid DOM and antibiotics is lacking. In the present study, the effects of colloidal DOM derived from pig manure and chicken manure on the transport of different antibiotics were examined in a cropland soil and an orchard soil. According to the breakthrough curves obtained for repacked soil columns (2.5 cm in diameter, 15 cm in height) under a simulated rainfall intensity of 20 mm/h, florfenicol was highly mobile and leached out almost simultaneously with the water flow tracer Br– for the cropland soil, which exhibited an 11%-23% higher leaching capacity than for the orchard soil. On the other hand, norfloxacin and tylosin did not penetrate through the column and most of their residues were retained in the top soil layer. Pig manure DOM delayed the breakthrough of florfenicol by 0.07-0.13 pore volume and increased its residues by 15%-26% as a result of enhanced retention through a co-sorption mechanism, and similar effects of chicken manure DOM were observed.
The German Climate Forecast System 2.1: seasonal forecast performance over Europe
Authors: Fröhlich Kristina , Isensee Katharina , Brandt Sascha , Brune Sebastian , Paxian Andreas , Baehr Johanna
Published: March 2021

In November 2020, the new version of the German Climate Forecast System, GCFS2.1, became operational at Deutscher Wetterdienst (DWD), providing new seasonal forecasts every month. The system is based on the Max Planck Institute for Meteorology Earth-System Model (MPI-ESM-HR) and is developed jointly by DWD, the Max Planck Institute for Meteorology and Universität Hamburg.

In GCFS2.1, ERA5 and ORAS5 reanalyses are assimilated using atmospheric, oceanic and sea ice nudging, respectively. From the assimilation, 50-member 6-month forecast ensembles are initialized at the start of each month. Prediction skill is assessed with a 30-member 6-month hindcast ensemble covering the time period 1982-2019 for February, May, August and November start months, and 1990-2019 for the remaining start months. Both the forecast and hindcast ensembles are generated by oceanic bred vectors with additional physical perturbations applied to the upper atmospheric model layers.

Here, we investigate the performance of GCFS2.1 summer and winter forecasts over Europe. While our main focus is on the prediction of large scale patterns that control the weather regimes during these two seasons, e.g. European blockings, special emphasis is paid on the impact of the January 2021 sudden stratospheric warming (SSW) event on the performance of GCFS2.1. The inclusion of the early phases of the January 2021 SSW event in the forecast initialisation significantly changes the GCFS2.1 forecast for February 2021 European surface climate. Prediction skill of GCFS2.1 for summer European blocking events will be also compared to the previous version GCFS2.0.
Assessing the residence time of water in volcanic lakes of north Cameroon using bomb-36Cl and stable isotopes
Authors: Abba Souleyman , Hamelin Bruno , Deschamps Pierre , Garcin Yannick , Badoga David , Tamonkem Adzeh Roger , Djangue Moustapha Bouba , Ngounou Ngatcha Benjamin
Published: March 2021

The Cameroon Volcanic Line (CVL) in Central Africa hosts numerous volcanic lakes. While Nyos and Monoun lakes in western Cameroon were well studied following the catastrophic release of CO2 that occurred in 1980s, other volcanic lakes such as those of the Adamaoua Plateau remain less documented. Although some of these (Mbalang and Tizon) have been investigated through their sedimentary archives in order to reconstruct past-environments, the functioning of these hydro-systems located in the northern part of the CVL is not well constrained. Here, we characterize the hydrological functioning of five volcanic lakes by coupling classical hydrology methods and isotope tracers. Specifically, we assess water residence time in these lakes using radioactive (36Cl) and stable isotopes of water.

36Cl is a cosmogenic isotope of chlorine produced naturally in the stratosphere by spallation of 40Ar induced by cosmic-rays and has been massively injected into the atmosphere by nuclear tests during the 1950s. This pulse of bomb-36Cl can thus be used as a tracer to estimate recharge rates in the unsaturated zone and to constrain water transit times at a regional scale. While water stable isotopes have been widely used to establish lakes hydrological balance in Sahelian regions, only a few studies have been reported to date using 36Cl for the same purpose in tropical areas.

In this study, together with major elements and stable isotopes, we analyzed 36Cl contents in water from lakes Mbalang, Tabere, Tizon, Gegouba and Baledjam around Ngaoundere, to assess residence time in these lacustrine systems. 36Cl/Cl ratios range from 1400.10-15 to 2800.10-15 at/at and are significantly higher than the natural baseline as assessed by data obtained in local groundwater or at a larger scale in the Lake Chad Basin (36Cl/Cl ~200.10-15 at/at, see Bouchez et al., Scientific Reports, 2019). These 36Cl/Cl ratios above the natural baseline are clearly tagged with the bomb-36Cl footprint. We will illustrate at the meeting how a simple transient-state one-box model can be used to explain why these lakes have different 36Cl/Cl ratios, and how these results can help to constrain the E/I ratios of the lakes, and be compared with their hydrological characteristics and stable isotopes signatures.
Multivariate postprocessing using Cholesky-based multivariate Gaussian regression
Authors: Muschinski Thomas , Mayr Georg J. , Simon Thorsten , Zeileis Achim
Published: March 2021

To obtain reliable joint probability forecasts, multivariate postprocessing of numerical weather predictions (NWPs) must take into account dependencies among the univariate forecast errors—across different forecast horizons, locations or atmospheric quantities. We develop a framework for multivariate Gaussian regression (MGR), a flexible multivariate postprocessing technique with advantages over state-of-the-art methods.

In MGR both mean forecasts and parameters describing their error covariance matrix may be modeled simultaneously on NWP-derived predictor variables. The bivariate case is straightforward and has been used to postprocess horizontal wind vector forecasts, but higher dimensions present two major difficulties: ensuring the estimated error covariance matrix is positive definite and regularizing the high model complexity.

We tackle these problems by parameterizing the covariance through the entries of its basic and modified Cholesky decompositions. This ensures its positive definiteness and is the crucial fact making it possible to link parameters with predictors in a regression.  When there is a natural order to the variables, we can also sensibly reduce complexity through a priori restrictions of the parameter space.

MGR forecasts take the form of full joint parametric distributions—in contrast to ensemble copula coupling (ECC) that obtains samples from the joint distribution. This has the advantage that joint probabilities or quantiles can be easily derived.

Our novel method is applied to postprocess NWPs of surface temperature at an Alpine valley station for ten distinct lead times more than one week in the future.  All the mean forecasts and their full error covariance matrix are modelled on NWP-derived variables in one step. MGR outperforms ECC in combination with nonhomogeneous Gaussian regression.
Climate field reconstruction of North Atlantic sea surface temperatures
Authors: Nilsen Tine , Talento Stefanie
Published: March 2021

Pseudo-proxy experiments test the skill and sensitivity of two extended climate field reconstruction (CFR) methodologies in reconstructing northern North Atlantic Summer sea surface temperatures (SSTs). The Summer target data originate from one millennium-long simulation of the CESM LME (Otto-Bliesner et al. 2016) .  The experiments test the reconstruction skill systematically for input data mimicking SST marine proxies and instrumental observations, including characteristics such as sparse distribution in space, varying signal-to noise ratio and age uncertainties.

The Bayesian hierarchical model BARCAST assumes implicitly that the target variable is described as an AR(1) process in time (Tingley & Huybers 2010), while the proxy surrogate reconstruction (PSR) method makes no such assumption (Graham et al. 2007). The PSR selects climate analogues from the simulated instrumental period in our study.

Results show that both methodologies generate skillful reconstructions for perfectly dated input data, and the PSR is superior when realistic noise levels are chosen for the input data. When the input is perturbed with age-uncertainties, the methodologies are unable to generate acceptable skillful reconstructions. Facilitating in form of data clustering is tested for both methodologies in the attempt of improving reconstruction skill. This proves successful for the PSR methodology, with the best skill obtained using n=3 clusters over the reconstruction region.

Additionally, and addressed as a topic for discussion, we detect weak temporal persistence in the input data and the BARCAST reconstructions. The lack of SST persistence is found to be partly due to the input data sampling frequency: Summer means (June, July, August) averaged for every year. Analyses show that the simulated SST data exhibit weaker memory from one Summer to the next, compared to year-to-year variability based on annual means. Similar results are also found for instrumental observations. This finding stands in contrast to results of previous studies on terrestrial reconstruction, where climate reconstructions and individual proxy records exhibit strong persistence properties, also targeting the Summer season (Werner et al. 2018, Nilsen et al. 2018),.

 

References:

Graham, N.E. et al. (2007), Clim. Change, 83, 241-285, doi: 10.1007/s10584-007-9239-2

Otto-Bliesner, B.L. et al (2016), Bull. Amer. Meteor. Soc., 97, 735-754, doi: 10.1175/BAMS-D-14-00233.1

 Nilsen, T. et al. (2018), Clim. Past, 14, 947-967, doi: 10.5194/cp-14-947-2018

Tingley, M. P. and P. Huybers (2010a), J. Clim., 23, 2759–2781, doi: 10.1175/2009JCLI3015.1

Werner, J. P. et al. (2018), Clim. Past, 14, 527-557, doi: 10.5194/cp-14-527-2018
EM-MHeatWaves: Eastern Mediterranean marine heatwaves - Ocean responses to atmospheric forcing and impacts on marine ecosystems
Authors: Xoplaki Elena , Tragou Elina , Gogou Alexandra , Zervakis Vassilis , Koutsoubas Drosos , Behr Lorine , Petalas Stamatis , Sini Maria
Published: March 2021

Even before the introduction of the term “Marine Heat Wave” (MHW) and its statistical definition in global-scale studies, the scientific community had studied and recorded potentially harmful impacts of persistent conditions of warm surface layers and highly stratified water columns on the marine ecosystem. The main triggers for MHWs are yet not well understood and the current knowledge is mainly based on mass mortalities linked to temperature anomalies. EM-MHeatWaves is an interdisciplinary, collaborative, DAAD/IKYDA funded research project that investigates the atmospheric forcing, oceanic circulation and ecosystem response of MHWs in the Eastern Mediterranean Sea over the past 35 years. Two universities (Justus-Liebig-University Giessen, University of the Aegean) and one research center (Hellenic Centre for Marine Research) re-examine the definition of MHWs with emphasis on the Eastern Mediterranean by applying a holistic approach that includes reverse-engineering using model data and reanalysis covering the period 1985 to 2014. We focus on the Eastern Mediterranean because of the high sensitivity of the basin’s ecosystem to atmospheric and marine warming events, the invasion of tropical alien (Lessepsian) species, the characteristic oceanic circulation with the Eastern Mediterranean Transient events, the exchange with the Black Sea through the Turkish Strait System as well as the coastal upwelling areas. In order to study the spatiotemporal characteristics of Eastern Mediterranean MHWs we work towards a better understanding of the oceanographic processes as well as of the compounding character of the atmospheric contribution. Based on the response of marine biogeochemical cycles (depletion of subsurface oxygen levels, observed changes in the mixed layer and chlorophyll maxima depths, nutrient stoichiometries, carbon uptake and sequestration rates) and their impacts on ecosystems (i.e. shifts in planktonic and benthic community regimes, mass mortality events, disease outbreaks, etc.), triggered by the rise of ocean temperatures, we study the statistical characteristics of the oceanic temperatures and assess the corresponding ocean circulation, the synchronous and lagged contribution of the large scale atmospheric circulation. We further study the signature of these extreme Mediterranean MHW events in future projections from model runs with respect to duration, severity and spatial extent and compare them to reanalysis.   
EM-MHeatWaves aims at strengthening the partnership between the German and Greek institutions by conducting joint research at a high scientific level.