bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic errors in Cryosat-2 swath elevations and their impacts on glacier mass balance estimates
Authors: Haacker Jan , Wouters Bert , Slobbe Cornelis
Published: March 2022

Almost ten years ago, the first elevation estimates based on swath processing of interferometric CryoSat-2 altimeter observations were published, mapping the surface of Devon ice cap. The new method holds a great potential to provide dense data coverage, in space and time. Indeed, ESA recently started releasing digital elevation models at a 2 by 2 km resolution for a rolling 3 month data aggregation cycle. Such spatiotemporal resolutions are especially valuable in versatile and dynamic regions as mountain glaciers. In this presentation, we describe systematic errors on the order of 10 m with about yearly periodicity that arise in the proximity of hills and valleys. One error is caused by the superposition of multiple signals, the other is caused by the Fourier-transformation in the SAR beam-forming process. Both are intrinsic to the measuring concept, but their effect can potentially be limited by data filtering strategies. We report the influence of the commonly used coherence and power threshold based filtering on derived elevation change rates. For data users, awareness of these issues is especially important to interpret the observations correctly and to understand that there is a large systematic part in the overall uncertainty.
WAVETRISK-OCEAN: an adaptive dynamical core for ocean modelling
Authors: Kevlahan Nicholas , Lemarié Florian
Published: March 2022

This talk introduces WAVETRISK-OCEAN, an incompressible version of the atmosphere model WAVETRISK with a free surface. This new model is built on the same wavelet-based dynamically adaptive core as WAVETRISK, which itself uses DYNAMICO’s mimetic vector-invariant multilayer rotating shallow water formulation. Both codes use a Lagrangian vertical coordinate with conservative remapping. The ocean variant solves the incompressible multi-layer shallow water equations with inhomogeneous density layers. Time integration uses barotropic–baroclinic mode splitting via a semi-implicit free surface formulation, which is about 34-44 times faster than an unsplit explicit time-stepping. The barotropic and baroclinic estimates of the free surface are reconciled at each time step using layer dilation. No slip boundary conditions at coastlines are approximated using volume penalization. The vertical eddy viscosity and diffusivity coefficients are computed from a closure model based on turbulent kinetic energy. Results are presented for a standard set of ocean model test cases adapted to the sphere (seamount, upwelling and baroclinic turbulence). An innovative feature of WAVETRISK-OCEAN is that it could be coupled easily to the WAVETRISK atmosphere model, thus providing a first building block toward an integrated Earth-system model using a consistent modelling framework with dynamic mesh adaptivity and mimetic properties.
Impact of plant cover on soil erosion, and barriers to cover crop use in Spanish orchards.
Authors: Ripley Helena , Stevens Carly , Quinton John
Published: March 2022

Soil erosion is high in hillside orchards in Spain. Climate change is causing an increase in the length of dry periods and intensity of rainfall, which exacerbates soil loss from fields. Due to the lack of rain during the summer, orchard farmers, concerned about water competition for tree crops, remove ground cover. However, without raindrop interception the soils are vulnerable to erosion and gullying. While cover crops between tree crops are beneficial in controlling soil erosion, farmers are slow to take up this practice. Both a mesocosm experiment identifying the value of vegetation cover, and survey responses from farmers about erosion management practices are outlined below.

Rainfall simulation was used in a mesocosm experiment to determine the effect of plant cover on sediment loss. Three species native to Spain were used in five treatments consisting of Brachypodium distachyon, Medicago sativa, Silene vulgaris, a mix of the three species, and a bare plot. The plots were raised to a 10o angle before subsampled runoff and sediment was collected under simulated rainfall. A questionnaire was sent to crop tree farmers in Spain asking about their experiences of soil erosion, techniques used to combat it, if any, and their views on methods of soil and water conservation.

Significantly higher (p < 0.05) rates of sediment loss were measured from the bare plots (34.26 ± 19.85 g min-1), relative to the vegetated ones (6.13 ± 8.27 g min-1). This indicates the importance of cover crops to reduce soil erosion. The farmers responding to the questionnaire are aware of this. From a total of 26 respondents, 88% believe that cover crops decrease erosion. However, 58% think that lack of knowledge about effective methods of erosion control is a barrier to implementing techniques.     

This presentation will give an overview of the methods used in carrying out rainfall simulation and the questionnaire, in addition to the results gathered.
Causes of Water-Use Efficiency Variability in Europe and Their Representation in the Community Land Model v5
Authors: Poppe Teran Christian , Naz Bibi , Baatz Roland , Hendricks-Franssen Harrie-Jan , Vereecken Harry
Published: March 2022

The water-use efficiency (WUE, carbon assimilation per unit of water-use) describes a major axis of variability of ecosystems and identifies how these are coping with environmental changes. However, the response of WUE to climate change and hydrological extremes between different ecosystems remains poorly understood. 

Here we investigated how the WUE of ecosystems in Europe varied from 1995 - 2018, as long-term trends and in response to precipitation (P) and soil moisture (SM) droughts. We aggregated data from remote-sensing and reanalysis to calculate three different WUE indices, conducted Mann-Kendall trend analyses and determined WUE anomalies for different hydro-climates and plant functional types during P and SM deficits. Finally, we applied the Peter & Clark Momentary Conditional Independence (PCMCI) algorithm to identify causative networks of environmental variables and WUE and differences among ecosystems.

We found extensive, negative long-term WUE trends in Eastern Europe, where WUE is predominantly controlled by carbon assimilation (GPP). Further, we identified soil moisture and transpiration control of GPP as drivers for the positive WUE response to droughts in arid ecosystems. In contrast, negative trends in humid ecosystems were driven mostly by temperature, which governed GPP variability.

In addition, outputs from a state-of-the-art land-surface and carbon model (CLM5-BGC) will be used to compare trends, drought response and the causative relationships with the ones from satellite and reanalysis data in order to evaluate the model representation of ecosystem variability.
Geomorphometric analysis for the hinterland of the roman sites Chimtou and Bulla Regia (Central Medjerda Valley), North Tunisia
Authors: Pagels Julia , Bebermeier Wiebke , von Rummel Philipp
Published: March 2022

The intra-mountain Medjerda Valley is located in North Tunisia and is characterized by its namesake the Oued Medjerda. The Valley has been settled since at least the latest Paleolithic period. Archaeologists from the German Archaeological Institute (DAI) have been studying the region since 1965, concentrating on Roman settlements. Since January 2021 the joint research project “Conquest, Ecology and Economy in Islamic North Africa: The Example of the Central Medjerda Valley” focuses on the subsequent Islamic settlement of the middle Medjerda Valley between Late Antiquity and the Early Medieval Period. The overall project aims to understand the economic and social transformations of the region triggered by the Muslim conquests and subsequent regime changes.

As part of this project, we want to focus on sediment archives in the immediate hinterland of the archaeological sites Chimtou and Bulla Regia, which are located in the central Medjerda Valley. We want to increase our knowledge on local changes in environmental conditions to establish a knowledge base on how economic and social change of the region affects the landscape balance and sediment fluxes.

In this presentation we will present a morphometric analysis of the study area: a GIS-based classification of landforms by applying the algorithm Geomorphons and results from a soil erosion model (USPED). Our results show that combing both methods allows us to derive information on landscape sensitivity, increases our process understanding and supports identify areas of erosion and deposition. Although we currently do not have the opportunity to go into the field, we here introduce a methodological framework, which allows a first geomorphological characterization of a study area – nevertheless, ground checking will be a task for future field work.
Optimizing reservoir operation rules for ecological sustainability by identifying dual effects of flow regime and water quality on metacommunity dynamics
Authors: Wang Yibo , Liu Pan , Solomatine Dimitri
Published: March 2022

Reservoir operation causes spatiotemporal variations in outflow, which influence the dynamics of downstream aquatic communities. However, empirical evidence of community responses to flow regime (FR) and water quality (WQ) remains limited for dam-regulated rivers. This study focused on identifying the influences of both FR and WQ on metacommunity dynamics downstream of the reservoir. First, the metacommunity dynamics model (MDM) was used to simulate aquatic community dynamics under changing FR and WQ. Then, the flow-ecology relationship was established to identify community response to reservoir outflow. Third, the novel ecological indicators were proposed to evaluate the resilience and resistance of multi-population systems. Finally, the reservoir operating rule curves were optimized by considering tradeoffs between socioeconomic and ecological objectives. The coevolution processes of multi-population systems (fish, phytoplankton, zooplankton, zoobenthos, and macrophytes) were simulated by MDM for each local community. The population densities of stable states showed continuous downward trends with increasing alteration degree of FR and WQ for multi-population systems, and aquatic community systems could be destroyed when alteration reached its acceptable maximum. The greater the alteration degree of FR and WQ, the longer the recovery time from an unstable to a stable state, and the weaker resistance for each population system. The resilience and resistance of downstream multi-population systems can be enhanced by optimizing reservoir outflow. The optimization results illustrated that all the performances of the multiple objectives of water supply, hydropower generation, and ecological benefits were improved by no less than 2.5% compared with the conventional operation. This study provided an approach to identify dual effects of FR and WQ on aquatic community systems, which is helpful in guiding ecological restoration for river ecosystems.
Detecting non-equilibrium states in atmospheric turbulence.
Authors: Waclawczyk Marta , Nowak Jakub L , Malinowski Szymon P
Published: March 2022

In this work we show how to retrieve information about temporal changes of turbulence in the atmosphere based on in-situ wind velocity measurements. The performance of our method is illustrated with the use of high-resolution data taken by a helicopter-borne platform ACTOS (Airborne Cloud Turbulence Observation System) in stratocumulus-topped boundary layer (STBL).

Atmospheric turbulence is a complex phenomenon, characterized by the presence of a plethora of scales (eddies). Turbulence may undergo large space and time variations due to rapidly changing external conditions, it may be locally suppressed or enhanced. To describe characteristic features of turbulence, statistical theories are sought for. In this context, a number of recent research works address the problem of the equilibrium Taylor’s law and its failure in the presence of rapid changes of the system. A new, non-classical, although universal scaling is introduced to describe the latter.

In this work we calculate two non-dimensional indicators, the dissipation factor and the integral-to-Taylor scale ratio and study their dependence on the Taylor-based Reynolds number. By analysing these results we can identify regions where turbulence is in its stationary state, with production balancing the dissipation and regions where turbulence decays in time or, on the contrary, becomes stronger. We also detect non-equlibrium turbulence states which indicate the presence of rapidly-changing external conditions. In this case the investigated statistics do not follow the equilibrium Taylor’s law, but both, the dissipation factor and the integral-to-Taylor scale ratio become inversly proportional to the Taylor-based Reynolds number. 

The presence of non-equilibrium turbulence in the atmospheric boundary layer has important implications, as it indicates that common turbulence closures may fail to predict the dynamics of such systems correctly.  Incorporating non-equilibrium effects to turbulence models may largely improve their predictions.
Satellite observations of the impact of individual aircraft on ice crystal number in cirrus clouds
Authors: Marjani Sajedeh , Tesche Matthias , Bräuer Peter , Sourdeval Odran , Quaas Johannes
Published: March 2022

Aviation outflow is the only anthropogenic source of pollution that is directly emitted into the upper troposphere. This emission has the potential to modify the cloudiness directly by forming linear contrails and indirectly by injecting aerosols, which can act as cloud condensation nuclei (CCN) and ice nucleating particles (INP). Contrail cirrus can persist either in cloud-free supersaturated air, increasing high-cloud cover or inside natural cirrus cloud, and therefore modifying the microphysical properties of already existing cirrus clouds. Even though the situation that an aircraft flies through a natural cirrus is one of the highly probable situations in the upper troposphere, its subsequent impact is unclear with the present state of knowledge. Quantifying such impact is necessary if we are to properly account for the influence of aviation on climate. One main limitation preventing us from better identifying these impacts is the lack of height resolved measurements inside the cirrus clouds.

In this study, we used new retrievals from combined satellite cloud radar and lidar (CloudSat/CALIPSO; DARDAR-Nice algorithm), which provide height resolved information of ice crystal number concentration, at intercepts between the CALIPSO ground track and the position of civil aircraft operating between the west coast of the continental United States (Seattle, San Francisco and Los Angeles) and Hawaii during 2010 and 2011 from an earlier study.

Comparing cloudy air behind the aircraft inside the flight track to the adjacent regions and to ahead of the aircraft revealed a notable difference in ice number concentration at 300 m to 540 m beneath the flight height. These differences are derived from the reduction of ice number concentrations as we proceed toward the cloud base in regions unaffected by aviation and the increase of ice crystals as we distance a few hundreds of meters beneath the flight level in the regions affected by aviation.
Planetary limits to soil degradation
Authors: Kraamwinkel Clarisse , Beaulieu Anne , Dias Teresa , Howison Ruth
Published: March 2022

Soils are essential to life on Earth but are rapidly degrading worldwide due to unsustainable human activities. We argue that soil degradation constitutes a key Earth system process that should be added as 10th Earth system process to the planetary boundaries framework.

Soil degradation shares all key traits with the nine Earth system processes already present in the planetary boundaries framework. It is caused by human activity, has the potential to cause unacceptable environmental change, shows tipping point behavior when forced beyond a critical level, is relevant on both local and global scales, and is strongly interrelated with the other Earth system processes. 

Healthy soils have a level of resilience against disturbances but once forced beyond a critical level, they are at risk of entering into a downward spiral of degradation fuelled by strong positive feedback loops. Well-documented examples include the local feedback between loss of soil structure and soil biota and the large-scale feedback loop between soil erosion and climate change. The final degraded state of the soil is unable to sustain human life on earth. The fall of past civilizations has been related to their inability to protect the soil. At present, ~33% of the global soils are moderately to severely degraded as a direct result of human activities such as unsustainable agricultural practices, urban expansion, and industrialization. Estimates show that by 2050, 90% of our soils will be degraded, the majority of our ecosystems will be compromised and the entire human population will be affected.

Soils are essential to life on Earth through the provision of soil functions and ecosystem services such as biomass production (including ~95% of the food we eat), climate regulation, water storage and purification, habitat provision, and nutrient cycling. They play a key role in achieving many of the Sustainable Development Goals (SDGs) including SDG 15: life on land, SDG2: zero hunger, and SDG6: clean water and sanitation. Soil degradation leads to critical disruptions to biosphere integrity, biogeochemical flows, climate change, and land-system change, all processes that have already crossed their planetary boundaries. Hence, in order to improve the planetary boundaries framework and clearly signal the need to protect the soil, we call for soil degradation to be considered the 10th Earth system process in the planetary boundaries framework. 
Using continuous resistivity profiling (CRP) method to identify electrical resistivity variations related to FSGD areas.
Authors: Tur-Piedra Jose , Folch Albert , Queralt Pilar , Marcuello Alex , Ledo Juanjo
Published: March 2022

The characterization of fresh submarine groundwater discharge (FSGD) in coastal aquifers has been the object of study in many investigations due to the importance of water as a strategic resource for populations. However, investigating processes that occur in the part of the aquifer located under the sea entails greater difficulties. 
The objective of this study has been to characterize FSGD in the coastal alluvial aquifer of Maresme, located 40 km north of the city of Barcelona. To study the marine part of the aquifer with good spatial resolution, the geophysical method of continuous resistivity profiling (CRP) has been chosen. Marine profiles, parallel and perpendicular to the coastline, have been done using a boat in a shallow water area to obtain electrical resistivity data of the seabed covering 3 km2. Data acquisition has been carried out in two field campaigns, one in the dry season and another in the wet season. 
From the results obtained, it has been possible to observe different electrical resistivity values in marine sediments along the coast. These variations have also been identified between the two campaigns, being the wet season the one with the highest electrical resistivity values. This study shows that CRP is a non-invasive method that allows the detection of resistive zones of marine sediment that have been related to preferential discharge areas.

Acknowledgments
This work was partly funded by the Spanish Government (grant no. PID2019-110212RB-C22) and the project TerraMar (grant no. ACA210/18/00007) of the Catalan Water Agency.
Reuse of deactivated cement-asbestos waste as inorganic filler in elastomers and epoxy resins
Authors: Fabrizio Vergani ,   Progetto Dear
Published: March 2022

Asbestos minerals, namely chrysotile and fibrous amphiboles, have long been used as components in construction materials, as for instance the cement-asbestos (CA) slates used in roofing, exploiting their capability to increase mechanical strength. As well known, asbestos minerals have been recognised toxic and banned almost worldwide. Current remediation approaches include confinement, encapsulation and removal (followed by disposal in controlled landfills). A more attractive solution, strongly recommended by the EC, is detoxification and reuse, in a perspective of circular economy.

In the present contribution we explored the possibility to reuse thermally treated and deactivated CA powder (a mixture of glass and Ca-Mg silicates typical of cement – details in Vergani et al. 2021) as filler in: i) flour-elastomers (FKM type, characterized by high resistance to oil and temperature) and bi-component epoxy resins (bisphenol-A, epichlorohydrine based resins) used in flooring. For each application, different formulations (different proportions of conventional raw materials and deactivated CA powder) have been prepared and tested according to conventional quality test protocols and SEM micro-textural observations.

As regard the reuse in epoxy resin, the inert CA powder was used either as unique inorganic filler (up to 30 wt%) or admixed to conventional ones (barite), in varying proportions (up to 10 wt%). Mechanical tests and SEM observations have shown encouraging results for all formulations, suggesting feasible reuse in this field.

The application of the inert CA powder as filler in fluor-elastomers in substitution of wollastonite (~22 wt%) or barite (~7 and ~14 wt%), has given some controversial results. Although rheological properties such as cure kinetics, viscosity and scorch temperature are comparable to the standard reference samples, some important physical-mechanical properties worsen because of compatibilization and dispersion problems. As demonstrate by SEM observations, the CA powder tends to agglomerate, and similarly to the coarser particles saved from ball-milling – the grain size distribution of the CA powder is tri-modal with peaks at ~35-40, ~4-5 and ~0.7-0.8 µm – separate from the elastomer, adding porosity with detrimental effects on breaking load, elongation at fracture and related M50 and M100 modules.

At the moment, in a perspective to keep the fine fraction low and to reduce the coarse particles, alternative milling procedures, including microwave and ultrasonic treatments and sieving, are evaluated.

Reference: Vergani et al. (2021) J. Mater. Cycles Waste. https://doi.org/10.1007/s10163-021-01320-6
Sentinel-6 Orbit Determination at the Copernicus POD Service
Authors: Fernandez Sanchez Jaime , Peter heike , Fernandez Marc , Femenias Pierre , Andres Yago
Published: March 2022

The Copernicus POD (Precise Orbit Determination) Service is a consortium responsible for providing orbit products and auxiliary data files from the Copernicus Sentinel-1, -2, -3, and -6 missions to the corresponding Payload Data Ground Segment (PDGS) processing chains at ESA and EUMETSAT. Products and data are also made available to external users through the ESA Copernicus Open Access Hub.

Sentinel-6 Michael Freilich launched in November 2020 is the newest satellite in the Copernicus POD Service operations. A near real-time orbit product computed based on GNSS data is delivered to EUMETSAT, acting as backup the DORIS DIODE aboard. For the first time, a combined GPS and Galileo receiver is used for POD. In addition, the satellite is equipped with a DORIS receiver and a Laser Retro Reflector for Satellite Laser Ranging (SLR). Additional GPS observations usable for POD are delivered from the POD antenna of the GNSS-RO (radio occultation) instrument. All these observations allow for various cross-comparisons between orbits from the different observation techniques and instruments. The quarterly and yearly Regular Service Reviews include validation of post-processed Sentinel-6 orbit solutions from various members of the Copernicus POD Quality Working Group (QWG).  

This contribution focuses on post-processed POD based on the combined GPS & Galileo receiver and validation with SLR done at the Copernicus POD Service. Precise orbits may be derived as single-system or combined solutions. Integer ambiguity resolution is a key technique to obtain highest accuracy orbits.

Precise orbit determination results from GPS-only, Galileo-only and combined GPS & Galileo observations with resolved integer ambiguities are presented. Cross-comparison between the different solutions, SLR validation, and comparison to other orbit solutions provided by members of the Copernicus POD QWG are shown and analysed.
The effect of soil erosion depth on maize yields, evidence based on a long-term field simulation experiment 
Authors: Rong Li , Duan Xingwu , Liu Taicong , Qin Yuhong
Published: March 2022

Despite soil erosion has a strong impact on crop yield, whether soil erosion depth leads to abrupt or gradual crop yield changes is not well understood. To investigate how crop yields respond to soil erosion depth, we conducted a simulated erosion experiment by adopting the cut-and-fill method from 2012 to 2018 in a typical mountain area in the southeastern China. A completely randomized design with five soil erosion depth (5, 10, 20, 30 and 40 cm soil cut) and a control (0 cm soil cut) were used. Each treatment had three replicates. Maize was planted in these simulated erosion plots and maize yields were monitored from 2012 to 2018. Our results showed that the maize yield decreased with erosion depth and with decreasing remaining Ap horizon depth. Inconsistent with earlier studies, maize yield exhibited a quadratic function rather than linear response to increase in soil erosion depth and decrease in remaining Ap horizon depth. Soil erosion depth led to abrupt changes in maize yield. Compared with control, maize yield did not decrease significantly at 5 cm erosion depth or ＞25 cm remaining A horizon depth, but its reduction rate per 1cm of soil loss (3.36%) increased sharply at 10 cm erosion depth or 20 cm remaining Ap horizon. When remaining Ap horizon left 10 cm, maize yield demonstrated the lowest, which may be irreversible via application of chemical fertilization. Considering high heterogeneity of Ap horizon in the mountain area, soil erosion-crop yield relationship could be expressed well by remaining Ap horizon. We also found remaining Ap depth had a significant direct and indirect (via reduced SOM, soil available water, AP and AK contents) negative effect on maize yield. These results could be useful in identifying allowable soil-loss thickness and highlight the importance of soil nutrient monitoring in different soil erosion levels in designing a fertilization scheme aimed at ensuring food security.
Late-glacial to Neoglacial evolution of glacier extent and surface mass balance in the Cordillera Blanca, Peruvian Andes
Authors: Leger Tancrède , Hein Andrew , Goldberg Daniel , Fabel Derek
Published: March 2022

Cordillera Blanca glaciers represent the greatest glacial freshwater reserve in tropical South America and have been shrinking substantially over recent decades, posing a threat to future water resources in the Peruvian Ancash region. A crucial step to better understand the evolution of these glaciers under changing conditions is to establish robust reconstructions of their past response to climate fluctuations. Such reconstructions are limited in the tropical Andes, which inhibits our understanding of the climatic drivers of tropical glacier length and surface mass balance changes. The relative importance of temperature versus precipitation rate changes on glacier length changes is therefore still debated in the region. Here, we present 42 cosmogenic 10Be exposure ages from moraine boulder samples, establishing for the first time a comprehensive chronology for Late-glacial, Holocene and Neoglacial advances of four distinct Cordillera Blanca mountain glaciers. We use this chronology to constrain a series of moraine-matching numerical model-run simulations conducted for each dated glacier advance using a spatially-distributed ice-flow model coupled with a positive degree-day surface mass balance parameterisation. These simulations aim at modelling and estimating former three-dimensional glacier geometries, equilibrium line altitudes, surface mass balance properties and their evolution through time. This analysis also enables us to use glacier surface mass balance as a proxy for past atmospheric temperature and precipitation variations at the time of the reconstructed glacier advances. This new, multi-method glacier reconstruction enables, for the Cordillera Blanca: 1) novel glacio-geomorphological interpretations, 2) an improved understanding of glacier extent, surface mass balance and volume change during the Late-glacial, Holocene and Neoglacial phases of advance, and 3) new estimations of paleoclimate conditions required for the reconstructed glacier events to occur.   
Updated PSC climatology based on CALIOP measurements from 2006-2022 
Authors: Pitts Michael , Poole Lamont
Published: March 2022

After more than three decades of research, the roles of polar stratospheric clouds (PSCs) in stratospheric ozone depletion is well established. Heterogeneous reactions on PSCs convert the stable chlorine reservoirs HCl and ClONO2 to chlorine radicals that destroy ozone catalytically. PSCs also prolong ozone depletion by delaying chlorine deactivation through the removal of gas-phase HNO3 and H2O by sedimentation of large nitric acid trihydrate (NAT) and ice particles. A substantial recovery of the ozone layer is expected by the middle of this century with reduced global production of ozone depleting substances in accordance with the Montreal Protocol and subsequent amendments. But as climate changes, leading to a colder and perhaps wetter stratosphere and upper troposphere, reliable model predictions of recovery of the Antarctic ozone hole and of potentially more severe ozone depletion in the Arctic are challenging. This is due both to a lack of detailed understanding of the underlying physics and the fact that many global models use simple parameterizations that do not accurately represent PSC processes.

A more complete picture of PSC processes on vortex-wide scales has emerged from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) instrument on the CALIPSO satellite that has been observing PSCs at latitudes up to 82 degrees in both hemispheres since June 2006. The CALIOP Version 2.0 (v2) PSC algorithm was recently developed to address known deficiencies in previous algorithms and includes additional refinements to increase the robustness of the inferred PSC composition. In this paper, we present an updated PSC reference data record and comprehensive climatology constructed by applying the v2 algorithm to the more than 16-year CALIOP spaceborne lidar dataset. In addition to showing 4-D (latitude, longitude, altitude, and time) information on the occurrence, composition, and variability of PSCs in both hemispheres, we also compare the post-Pinatubo CALIOP PSC data record with the 1979-1989 SAM II (Stratospheric Aerosol Measurement II) solar occultation PSC record to investigate possible long-term variability in PSC occurrence.
Science and technology in deep unerground laboratories
Authors: Ianni Aldo
Published: March 2022

Deep Underground Laboratories (DULs) are large research infrastructures with a minimum rock overburden equivalent to one km water equivalent. In DULs the flux of muons from cosmic rays is reduced by several order of magnitude with respect to the surface. This allows to perform research on very rare events, such as exotic radioactive decays, double beta decays, low energy neutrino and dark matter interactions. The phenomenon of neutrino oscillations has been discovered in DULs back in 1998. Solar neutrinos were first observed in a DUL in 1968. As of today thanks to research carried out in DULs over four decades we have studied in detail the energy production mechanisms in the sun’s core. In 1987 neutrinos from a core collapse supernova in the Large Magellanic Cloud were observed confirming our basic understanding of this high energetic event. DULs, at present, are equipped with more sensitive and better performing experiments to improve significantly these early studies. The large SuperKamiokande detector in Japan can observe as many as ten thousand events for a core collapse supernova at the center of our galaxy. The Borexino experiment in Italy has observed CNO neutrinos which contribute to only 1% of the energy production in the sun but are very important for more massive stars. All these crucial measurements could have not been possible without operating experiments in a deep underground site.

In the last decade the research horizon in DULs has expanded to include gravitational waves, geophysics, astrobiology, and biology in underground environments.

DULs are equipped with facilities to measure low levels of radioactivity by means of different techniques. This offers a unique opportunity to study living organism in a low radioactivity environment, namely with a significant reduction of cosmic rays and neutrons with respect to surface. DULs are being used by a large community of scientists ranging from astrophysicists, particle physicists, geophysicists, and biologists. There are 14 DULs in operation worldwide which correspond to about one million cubic meters excavated.

In the talk a brief review of DUL’s main features and research activities will be discussed. 
Accurate calculation of pressure forces on cells defined by steeply sloping coordinates
Authors: Bell Michael J , Bruciaferri Diego
Published: March 2022

The NEMO ocean model has a fairly generic s-level vertical co-ordinate option that allows the model levels to follow either the ocean bathymetry resolved by the model or a smoothed "envelope'' version of it. Sufficiently accurate calculation of the net horizontal pressure forces on the resulting steeply sloping cells is well known to be difficult and many schemes have attempted to address this issue. We focus here on two types of schemes that calculate these forces by integrating around the cell perimeters (or faces). The first type calculates the pressure forces on the faces of each velocity cell first as proposed by Lin (1997). The second type is a re-arrangement of Song's density Jacobian scheme derived by Shchepetkin & McWilliams (2003). In these schemes the density and the height along coordinate surfaces are approximated by local piecewise continuous polynomial reconstructions and the integrals are calculated by direct integration of the polynomials or by quadrature methods. Higher order schemes are obtained by using higher order polynomials. In some cases these polynomials are constrained to avoid over-fitting of potentially noisy fields. We have implemented these schemes in NEMO treating model variables as point values rather than cell-mean values. The implementation for the second type follows previously published work closely whilst that for the first type differs somewhat from previous work. We have also implemented a ``pre-processing'' step that calculates cubic reconstructions of the density profile at the deepest point in the stencil used to calculate the net horizontal forces. The ``pre-processing'' step subtracts this interpolated profile from all the other profiles in the stencil. We present results for these schemes in a standard sea-mount test case with steep bathymetry and horizontal density surfaces in which the currents should be identically zero. We show that both types of schemes using appropriate quadratic or cubic reconstructions give currents that are one order of magnitude smaller than those given by second order accurate schemes. We also show that in this test case applying the ``pre-processing'' step with a second order accurate scheme provides results that are competitive with the higher order schemes. We also discuss some results for the “realistic” Atlantic Margin Model domain, priorities for further work and the development of schemes that treat model variables as grid-cell mean values.
Mechanical forcing of the North American monsoon by orography
Authors: Pascale Salvatore , Boos William
Published: March 2022

The core of the North American monsoon (NAM) is characterized by a band of intense rainfall along the western coast of Mexico. This rainfall band is commonly understood to be caused by thermal forcing from both the elevated terrain of that region (Sierra Madre) and land. This fits into the general paradigm of monsoons as thermally direct circulations driven by heat sources. In this talk, instead, we show that the NAM rainfall is generated by the interaction of the extratropical jet stream with mountain ranges. We reach this conclusion using observations, a high-resolution global climate model, and stationary wave solutions to show that the NAM core rainfall band arises when Mexico’s Sierra Madre mountains mechanically force an adiabatic stationary wave through the equatorward diversion of extratropical westerly winds; westerly, upslope flow associated with that stationary wave then lifts warm and moist air to cause convective rainfall. Heat fluxes at the surface precondition the atmosphere for convection, especially in summer afternoons, but they alone are insufficient to produce the observed rainfall maximum.

 

These results, together with dynamical structures in observations and models, indicate that the core monsoon should be understood as convectively enhanced orographic rainfall in a mechanically forced stationary wave, not as a classic, thermally forced tropical monsoon. This has implications for the response of the NAM to past and future global climate change, making trends in jet stream interactions with orography of central importance.
Tree-ring width as an indicator for hydroclimate variability in the Lower Danube region
Authors: Nagavciuc Viorica , Roibu Cătălin-Constantin , Mursa Andrei , Știrbu Marian Ionuț , Popa Ionel , Ionita Monica
Published: March 2022

Paleoclimate reconstructions are increasingly used to characterize climate variability and change prior to the instrumental record, in order to improve our estimates of climate extremes and to provide a baseline for climate change projections. Most of these reconstructions are focused on temperature, precipitation, and/or drought indices, and to a lesser extent to reconstruct streamflow variability. In this study, a regional tree-ring width chronology (i.e. Quercus petraea), from Caraorman forest (Danube Delta, Romania), was used to reconstruct the last ~250 years of annual (from November previous year to July current year) streamflow of the Lower Danube River. The obtained results indicate a stable and significant correlation between the measured tree-ring width from Caraorman forest and Danube streamflow at Ceatal Izmail hydrologic station situated in the south-eastern part of Europe. The statistical parameters of the reconstruction model confirm that our model is stable and robust, explaining 44.9 % of the variance of the Lower Danube streamflow over the period 1920 – 2013. Interannual streamflow variation for the analyzed period indicates 11 extremely high flow years, with streamflow greater than 9200 m3/s (1170, 1771, 1799, 1836, 1838, 1839, 1871, 1876, 1877, 1940, and 2010) and 11 extremely low flow years, with streamflow lower than 5200 m3/s (1750, 1753, 1753, 1773, 1794, 1832, 1843, 1882, 1921, 1964, and 1994). The influence of the large-scale atmospheric circulation on the TRW variability was analyzed using the composite maps of the geopotential height at 500 mb (Z500) and sea surface temperature (SST). High TRW values (e.g. high streamflow periods) from the Caraorman forest are associated with a low-pressure system centered over Europe and positive SST anomalies over the Atlantic Ocean and negative SST anomalies over the Baltic, North, and Mediterranean Seas. These large-scale conditions favor the advection of moist air from the Mediterranean and the Black Sea towards the south-eastern part of Romania, which in turn leads to high precipitation rates over this region. Opposite to this, low TRW values (e.g. low streamflow periods) are associated with a high-pressure system centered over Europe, a northward shift of the storm tracks and negative SST anomalies over the Atlantic Ocean, and positive SST anomalies over the Baltic, North, and Mediterranean Seas. Based on our results we argue that the reconstruction of river streamflow data based on the tree-ring width has important scientific and practical implications for a better understanding of the streamflow variation of the past, necessary for water resource management, and environmental-hydrological protection.
Multi-scale temporal analysis of actual evaporation on a saline lake in the Atacama Desert
Authors: Lobos Roco Felipe , Hartogensis Oscar , Suarez Francisco , Huerta Viso Ariadna , Benedict Imme , de la Fuente Alberto , Vila-Guereau de Arellano Jordi
Published: March 2022

Evaporation is a key component of the water cycle in the endorheic basins of the Chilean Altiplano. In this study, sub-diurnal to climatological temporal changes of evaporation in a high-altitude saline lake ecosystem in the Atacama Desert are analysed. We analyse the evaporation trends over 70 years (1950-2020) at a high-spatial resolution. The method is based on the downscaling of 30-km hourly resolution ERA5 reanalysis data to 0.1-km spatial resolution data using artificial neural networks. This downscaled data is used in the Penman open water evaporation equation, modified to compensate for the energy balance non-closure and the ice cover formation on the lake during the night. Our evaporation estimates show a consistent agreement with eddy-covariance measurements and reveal that evaporation is controlled by different drivers depending on the time scale. At the sub-diurnal scale, mechanical turbulence is the primary driver. At the seasonal scale, more than 70% of the evaporation variability is explained by the radiative contribution term. At interannual scales, evaporation increased by 2.1 mm per year during the entire study period according to global temperature increases. Last, we find that yearly evaporation depends on the El Niño Southern Oscillation (ENSO), where warm and cool ENSO phases are associated with higher evaporation rates and precipitation rates, respectively. Our results show that warm ENSO phases increase evaporation rates by 15%, whereas cold phases decrease by 2%. This investigation contributes with reliable long-term evaporation estimates over a typical saline lake of an arid region and a replicable methodology for climate change assessment and sustainable water management. 
The Gavon basin: a model of post-glacial debris-flow
Authors: Martin Silvana , Gabrieli Fabio , Da Ros Matteo , Rossato Sandro , Brezzi Lorenzo , Rigo Manuel , Monegato Giovanni
Published: March 2022

The Gavon basin hosts one of the major landslide deposits of the Eastern Italian Dolomites (Falcade, Belluno). This deposit is due to different phases of erosion carried out by the Gavon, which is a sinistral tributary of the Cordevole River, and it consists of a thick erodible sequence of Upper Permian Bellerophon Formation and Lower Triassic Werfen Formation (divided into Tesero, Mazzin, Andraz, Siusi, Gastropod Oolite, Campil, Val Badia, Cencenighe, San Lucano Members) that have been tectonically duplicated by thrust activity and uplifted by two superposed folding and diapiric deformations, rising the sequence to an elevation of 2499 meters a.s.l. at the Forca Rossa pass.

The Gavon basin is 5.98 km long and is characterized by a mean slope greater than 18%. The Lower Triassic sequence was eroded producing a 7.86 km2 basin in pre-glacial time. The basin was filled up by early landslide deposits before the last glaciation, which onset date back to about 30 thousand years before present, and during historic time.

The catchment is now subjected to high erosion due to the frequent rainfall/snowfall events. The solid transport has always been high (up to 34400 m3/y) and, for this reason, some dams were built 80 years ago. Three more check dams were built in 2005 to further decrease the erosion.

A reconstruction of the events in the postglacial time is carried out based on (a) the volume of the deposits and (b) the missing volume in the detachment area. A volume of 173 to 216 million cubic meters has been eroded by a series of events (or a unique large event) that ended approximately 4000 years ago (Fenti, 2018).

To complete this analysis, we numerically modelled the detachment and runout of a block of rock located in the top portion of the basin, where some tension cracks are now evident, and assuming that an intense rain event could mobilize it. The analysis has been processed using LiDAR data with QGis software, while the simulations are performed with GeoFlow-SPH.
Chloroplast harvesting by a miliolid expands the evolutionary range of kleptoplasty in foraminifera 
Authors: Pinko Doron , Abramovich Sigal , Rahav Eyal , Natasha Belkin , Rubin Blum Maxim , Holzmann Maria , Abdu Uri
Published: March 2022

Foraminifera are highly abundant marine unicellular eukaryotes. They are known for their important ecological role in most marine ecosystems, their major contribution to the carbon cycle, and their remarkable physiological plasticity. Many foraminiferal species have mixotrophic metabolism that is often based on partnerships with diverse algae, or in some cases, on harvesting diatom chloroplasts, known as kleptoplasty. To date, kleptoplasty was shown only in rotaliid lineages. Here, we report the first discovery of a diatom kleptoplasty in the Hauerina diversa, a tropical shallow-water miliolid that is an unexpected candidate for this life strategy. To elucidate this adaptation, we collected H. diversa specimens from the southeastern Mediterranean coast and visualized many intact chloroplasts in clustered structures within the foraminiferal cytoplasm using transmission electron microscopy. Preliminary genetic analyses confirmed that the harvested chloroplasts originated from diatoms. Primary production estimates using isotopically labeled NaH14CO3 as a carbon source suggest photosynthetic activity of the ‘stolen’ chloroplasts inside the host cell. This activity was found to be about two orders lower compared to the diatom-bearing species Amphistegina lobifera. We finally provide the first molecular phylogeny of H. diversa and its evolutionary relationship to ancient alveolind foraminifera. We thus demonstrate the first case of kleptoplasty in the ancient group of alveolind-miliolids, expanding the evolutionary range of kleptoplasty in foraminifera