bluuebunny/crossref_metadata_2025 huggingface dataset:
DACAPO-PESO: Remote Sensing and In-situ Observations in Sub-Antarctica (53°S,71°W) to Enhance the Understanding of Aerosol-Moisture-Cloud-Precipitation Interaction
Authors: Kalesse Heike , Seifert Patric , Radenz Martin , Bühl Johannes , Vogl Teresa , Schimmel Willi , Foth Andreas , Teisseire Audrey , Baars Holger , Engelmann Ronny , Barja Boris , Witthuhn Jonas , Stratmann Frank , Ansmann Albert , Zamorano Felix
Published: March 2020

The southern midlatitudes and Sub-Antarctica are a key region for the Earth’s climate and a source for uncertainties in climate modelling. The low concentration of ice nucleating particles is considered to diminish the efficiency of heterogeneous ice formation. Climate models underestimate the supercooled liquid water content which causes shortwave radiation biases.

The project DACAPO-PESO (Dynamics, Aerosol, Cloud And Precipitation Observations in the Pristine Environment of the Southern Ocean) which is being conducted in Punta Arenas (53°S, 71°W), Chile from Nov 2018 – March 2020 is endorsed by YOPP (Year of Polar Prediction) and fills an observational gap in the Southern Oceans, for which to date hardly any combined observations of lidar, cloud radar and microwave radiometer are available.

During that field experiment, LACROS (Leipzig Aerosol and Cloud Remote Observations System) of Leibniz Institute for Tropospheric Research (TROPOS) which comprises numerous remote sensing instruments, including multi-wavelength polarization Raman lidar, cloud radars, microwave radiometer, radiation sensors among others is deployed. From March 2019 onwards, additionally in-situ observations of the INP and cloud condensation nuclei properties were collected by TROPOS on a 623m high mountain 10 km upwind of the LACROS site. Meso-scale numerical modeling will provide support for interpretation of the results.

The presentation will be dedicated to

a) provide an overview of the setup of DACAPO-PESO

b) show case studies of how instrument synergies are used to characterize aerosol-cloud-interaction processes in the pristine atmosphere over Punta Arenas and

c) show a case study of an Atmospheric River event which was also observed in Antarctica.
Volcanic ash chemical aging from multiple observational constraints for the Pinatubo eruption
Authors: AbdelKader Mohamed , Stenchikov Georgiy , Bruhl Christoph , Lelieveld Jos
Published: March 2020

 

Condensation of sulfuric acid formed from the co-injected sulfur dioxide on volcanic ash particles, so-called chemical aging, increases the particle size and changes their microphysical and optical properties. The larger aged particles have a higher removal rate, which reduces their lifetime. On the other hand, the aging increases the scattering cross-section, and therefore the ash optical depth is increasing due to aging. The uptake of sulfuric acid by volcanic ash delays the formation of new sulfate particles depending on the level of aging, which is characterized by the number of sulfuric acid layers coating a single ash particle (i.e., monolayers). Both the formation of sulfate aerosols and sulfuric acid uptake by ash particles affect the development of a volcanic plume and its radiative impact.

We employ the ECHAM5/MESSy atmospheric chemistry general circulation model (EMAC) to simulate the chemical aging of volcanic ash in the 1991 Pinatubo eruption volcanic plume. We emit 17Mt of SO2 and 75Mt of fine ash. Two aerosol modes represent ash size distribution: accumulation and coarse with 0.23 and 3.4 um median radii, respectively. We allow the sulfuric acid to condense on the ash particles and assume different levels of aging (from not aged to highly aged). We use independent observations for sulfur dioxide, volcanic ash mass, volcanic ash optical depth, and plume coverage area from the Advanced Very-High-Resolution Radiometer (AVHRR) observations and total optical depth from the Stratospheric Aerosol and Gas Experiment II (SAGE II). We constrain the number of monolayers on ash particles by testing simulated ash surface area and optical depth calculated within a fully coupled online stratospheric-tropospheric chemistry model against observations. The level of volcanic ash aging strongly affects the surface area of the volcanic ash plume, ranging from 3x106 km2 to 6x106 km2, compared to 3.8x106km2 from AVHRR retrievals. The volcanic ash optical depth, averaged over the volcanic plume area, ranges between 2 and 3.6. Using five monolayer coating assumption allows us to better reproduce the observed SO2 mass, its decay rate, total plume surface area, and ash optical depth. Most of the coarse ash particles are removed within a week after the eruption reducing the amount of sulfuric acid within the volcanic plume. The smaller particles have much longer residence time and continue to uptake sulfuric acid for more than three months.

 

 
The source scaling of swarm-genic slow slip events
Authors: Passarelli Luigi , Rivalta Eleonora , Selvadurai Paul Antony , Jónsson Sigurjón
Published: March 2020

Slow slip events (SSEs) are slow fault ruptures that do not excite detectable seismic waves although they are often accompanied by some forms of seismic strain release, e.g., clusters of low- and very-low frequency earthquakes, and/or episodic or continuous non-volcanic tremor (i.e. tremor-genic SSEs) and earthquake swarms (swarm-genic SSEs). At subduction zones, increasing evidence indicates that aseismic slip and seismic strain release in the form of non-volcanic tremor represent the evolution of slow fracturing. In addition, aseismic slip rate modulates the release of seismic slip during tremor-genic SSEs. No general agreement has been reached, however, on whether source duration-moment scaling of SSEs is linear or follows that of ordinary earthquakes (cubic). To date, investigations on the source scaling has been based on global compilations of tremor-genic SSEs while no studies have looked into the source scaling of swarm-genic SSEs.

We present the first compilation of source parameters of swarm-genic slow slip events occurring in subduction zones as well as in extensional, transform and volcanic environments. We find for swarm-genic SSEs a power-law scaling of aseismic to seismic moment release during episodes of slow slip that is independent of the tectonic setting. The earthquake productivity, i.e., the ratio of seismic to aseismic moment released, of shallow SSEs is on average higher than that of deeper ones and scales inversely with rupture velocity. The inferred source scaling indicates a strong interplay between the evolution of aseismic slip and the associated seismic response of the host medium and that swarm-genic SSEs and tremor-genic SSEs arise from similar fracturing mechanisms. Depth dependent rheological conditions modulated by fluid pore pressure, temperature and density of asperities appear to be the main controls on the scaling. Large SSEs have systematically high earthquake productivity suggesting static stress transfer as an additional factor in triggering swarms of ordinary earthquakes. Our data suggest that during the slow slip evolution the proportion of seismic strain release is always smaller than the aseismic part although transient changes in stress and fault rheology imparted by swarm-genic SSEs can lead to delayed triggering of major and devastating earthquakes like in the Tohoku, Iquique and L’Aquila cases. The evidence of source scaling reported here will help constraining theoretical models of SSEs rupture propagation and seismic hazard assessments that should take into account the new scaling between aseismic and seismic moment release. 
Ad hoc estimation of glacier contributions to sea-level rise from latest glaciological observations
Authors: Zemp Michael , Huss Matthias , Eckert Nicolas , Thibert Emmanuel , Paul Frank , Nussbaumer Samuel U. , Gärtner-Roer Isabelle
Published: March 2020

Comprehensive assessments of global glacier mass changes based on a variety of observations and prevailing methodologies have been published at multi-annual intervals, typically towards IPCC reports. For the years in between, the glaciological method provides annual observations of specific mass changes but is suspected to not be representative at the regional to global scales due to uneven glacier distribution with respect to the full sample. Here, we present a framework to infer ad hoc (i.e., timely but preliminary) estimates of global-scale glacier contributions to sea-level rise from annual updates of glaciological observations. For this purpose, we combine the annual anomaly provided by the glaciological sample (relative to a decadal mean) with the (mean) absolute mass-change rate of a global reference dataset over a common calibration period (from 2006/07 to 2015/16). As a result, we provide preliminary estimates of regional and global glacier mass changes and related uncertainties for the latest hydrological years; i.e. about –300 ± 250 Gt per year in 2016/17 and –500 ± 200 Gt per year in 2017/18. These ad hoc estimates indicate that glacier contributions to sea-level rise exceeded 1 mm SLE per year which corresponds to more than a quarter of the currently observed rise. We also discuss the regional biases of the glaciological sample and conclude with a brief outlook on possible applications and remaining limitations of the glaciological observation network of the World Glacier Monitoring Service.
Improved global distributions of SF6 and mean age of stratospheric air by use of new spectroscopic data
Authors: Stiller Gabriele P. , Harrison Jeremy J. , Haenel Florian J. , Glatthor Norbert , Kellmann Sylvia , von Clarmann Thomas
Published: March 2020

The first and only global data set of mean age of stratospheric air (AoA) with dense day and night coverage has been derived from MIPAS observations by analysis of the spectral signature of SF6 (Stiller et al., 2008, 2012; Haenel et al., 2015). Since SF6 is a tracer with no sinks in the troposphere and stratosphere and an almost linearly increasing atmospheric abundance, it is often used to derive information on stratospheric transport and mixing due to the Brewer Dobson Circulation, quantified usually as mean age of stratospheric air (AoA). The global data sets of AoA derived so far from MIPAS observations, on basis of spectroscopically measured absorption cross sections by Varanasi et al. (1994), had a high bias in the middle to upper stratosphere compared to balloon-borne in situ observations from the 1990s. By applying a new spectroscopic data set measured in the laboratory recently (J.J. Harrison, to be published), we show that part of the high bias in AoA can be removed, and the residuals between measured and modelled atmospheric spectra can be decreased significantly. In this presentation we discuss the new SF6 and AoA distributions, variablilities and trends, and compare to previous versions and independent in situ observations. 

References:

Haenel, F. J., Stiller, G. P., von Clarmann, T., Funke, B., Eckert, E., Glatthor, N., Grabowski, U., Kellmann, S., Kiefer, M., Linden, A., and Reddmann, T.: Reassessment of MIPAS age of air trends and variability, Atmos. Chem. Phys., 15, 13161-13176, https://doi.org/10.5194/acp-15-13161-2015, 2015.
Stiller, G. P., von Clarmann, T., Höpfner, M., Glatthor, N., Grabowski, U., Kellmann, S., Kleinert, A., Linden, A., Milz, M., Reddmann, T., Steck, T., Fischer, H., Funke, B., López-Puertas, M., and Engel, A.: Global distribution of mean age of stratospheric air from MIPAS SF6 measurements, Atmos. Chem. Phys., 8, 677-695, https://doi.org/10.5194/acp-8-677-2008, 2008.
Stiller, G. P., von Clarmann, T., Haenel, F., Funke, B., Glatthor, N., Grabowski, U., Kellmann, S., Kiefer, M., Linden, A., Lossow, S., and López-Puertas, M.: Observed temporal evolution of global mean age of stratospheric air for the 2002 to 2010 period, Atmos. Chem. Phys., 12, 3311-3331, https://doi.org/10.5194/acp-12-3311-2012, 2012.
Varanasi, P., Li, Z., Nemtchinov, V., and Cherukuri, A.: Spectral Absorption–Coefficient Data on HCFC-22 and SF6 for Remote– Sensing Applications, J. Quant. Spectrosc. Radiat. Transfer, 52, 323–332, 1994.

 
Health-relevant influences of air substances and meteorological conditions
Authors: Koller Stephanie , Meisinger Christa , Wehler Markus , Hertig Elke
Published: March 2020

For a long time it has been known that exceptionally strong and long-lasting heat waves have negative health effects on the population, which is expressed in an intensification of existing diseases and over-mortality of certain risk groups (Kampa, Castanas 2008). Often associated with heat are stagnant airflow conditions that cause a large increase in the concentration of certain air substances (Ebi, McGregor 2008). Many of these air substances have a strong adverse effect on the human organism (Kampa, Castanas 2008).

The aim of the project is to investigate the actual hazard potential of health-relevant air pollution- and climatological variables by quantifying the effects on human health of increased exposure to air constituents and temperature extremes. Different multivariate statistical methods such as correlation analysis, regression models and random forests, extreme value analysis and individual case studies are used.

As a medical data basis for this purpose, the emergency department data of the University Hospital Augsburg are regarded. In addition to the diagnosis, supplementary information such as age, gender, place of residence and pre-existing conditions of the patients are used. Among the air constituents, the focus is on ozone, nitrogen dioxide and particulate matter. In the meteorological part, the focus is primarily on temperature, which is not only a direct burden but, as in the case of ozone, also has a decisive influence on the formation of ozone molecules. However, a large number of other meteorological parameters such as precipitation, relative humidity and wind speed as well as the synoptic situation also play a major role in the formation, decomposition process and the distribution of pollutants (Ebi, McGregor 2008).

The first major question to answer is whether air-pollution and meteorological stress situations are visible in the emergency department data. Further in-depth questions are which factors have the greatest negative impact, what is the most common environment-related disease, which weather conditions carry a higher than average risk and what are the health risks of climate change.

Ideally, the analysis may also provide a short-term forecast from which to derive whether or not there will be an above or below average number of visits to the emergency department.

The project is funded by the German Federal Foundation for Environment (DBU) and the German Research Foundation (DFG) - project number 408057478.

Literature

Ebi K., McGregor G. (2008): Climate Change, Tropospheric Ozone and Particulate Matter, and Health Impacts. doi: 10.1289/ehp.11463

Kampa M., Castanas E. (2008): Human health effects of air pollution. In: Environmental Pollution 151(2): 362-367. doi: 10.1016/j.envpol.2007.06.012
Glider observations of the Northwestern Iberian Margin during an exceptional summer upwelling season
Authors: Rollo Callum , Heywood Karen , Hall Rob , Barton Eric Desmond , Kaiser Jan
Published: March 2020

We present results from a 2 month deployment of an ocean glider over the Northwestern Iberian Margin. Glider observations during the exceptionally strong 2010 summer upwelling season resolved the evolution of physical and biogeochemical variables during two upwelling events. Upwelling brought low oxygen Eastern North Atlantic Central Water from 190 m depth onto the shelf up to a depth of 50 m. During the two observed periods of upwelling,
equatorward transport over the shelf increased from 0.13 (± 0.04) Sv to 0.18 (± 0.08) Sv and a poleward jet developed over the shelf-break. The persistent upwelling favourable winds maintained equatorward flow on the outer shelf for two months with no reversals during relaxation periods, a phenomenon not previously observed. During upwelling, near surface chlorophyll a concentration increased by more than 6 mg m-3 . Dissolved oxygen concentration in the near surface increased by more than 40 μmol kg-1 , 6 days after the chlorophyll a maximum.

This was the first and, to date, only deployment of a glider over the North West Iberian Margin. A single glider was able to occupy a cross shelf section for two months, without the need for a costly ship based campaign. This presentation highlights some of the challenges of using gliders to study shelf break regions.
Multiscale measures of phase-space trajectories
Authors: Alberti Tommaso , Consolini Giuseppe , Ditlevsen Peter D. , Donner Reik V. , Quattrociocchi Virgilio
Published: March 2020

Several attempts have been made in characterizing the multiscale nature of fluctuations from nonlinear and nonstationary time series. Particularly, the study of their fractal structure has made use of different approaches like the structure function analysis, the evaluation of the generalized dimensions, and so on. Here we report on a different approach for characterizing phase-space trajectories by using the empirical modes derived via the Empirical Mode Decomposition (EMD) method. We show how the derived Intrinsic Mode Functions (IMFs) can be used as source of local (in terms of scales) information allowing us in deriving multiscale measures when looking at the behavior of the generalized fractal dimensions at different scales. This formalism is applied to three pedagogical examples like the Lorenz system, the Henon map, and the standard map. We also show that this formalism is readily applicable to characterize both the behavior of the Earth’s climate during the past 5 Ma and the dynamical properties of the near-Earth electromagnetic environment as monitored by the SYM-H index.
Microstructural control on compaction localisation in granular materials
Authors: Carbillet Lucille , Heap Michael J. , Wadsworth Fabian B. , Baud Patrick , Reuschlé Thierry
Published: March 2020
Large field impressed anisotropy of magnetic susceptibility (AMS) in metamorphic volcanoclastic rocks from the western Central Pamir with ilmeno-hematite as the main magnetic carrier.
Authors: Roperch Pierrick , Aminov Jovid , Dupont-Nivet Guillaume , Guillot Stéphane , Lagroix France
Published: March 2020

Field impressed AMS fabric, although it has been recognized for a very long time, has been the subject of very few publications in the paleomagnetic literature. This effect has been mainly described in samples with magnetite as a main magnetic carrier. This fabric is usually of low magnitude and observed mainly in nearly isotropic rock after application of static AF demagnetization or after acquisition of an isothermal remanent magnetization (IRM). Forty four paleomagnetic sites have been sampled in a >2 km thick sequence of Cretaceous volcano-clastic rocks from the western Central Pamir mountain (Tadjikistan). These rocks present a medium grade level of metamorphism characterized by fine grained recrystallisation of biotite. The magnetic properties are very homogeneous across the sequence. Bulk magnetic susceptibilities vary between 150-250 μ SI. The AMS magnetic fabrics correspond to triaxial tensors with a well defined foliation plane and a steeply dipping magnetic lineation. The degree of anisotropy varies between 1.03 and 1.2. This fabric was likely acquired during the deformation associated with the emplacement of Middle Miocene gneiss domes. SEM/EDS data indicate that the main iron oxide mineral is hematite with up to 15% of ilmenite in solid solutions. This is in agreement with unblocking temperatures of SIRM around 630 °C, lower than the one of pure hematite. One of the most surprising magnetic characteristics of these rocks is the effect of strong-field remanent magnetizations upon the AMS. During the acquisition of an Isothermal Remanent Magnetization (IRM), the initial AMS is progressively obliterated by a new AMS fabric. The field-impressed AMS is characterized by a decrease of the magnetic susceptibility along the direction of the IRM and an increase in magnetic susceptibility in the orthogonal plane. The field-impressed AMS is thus mainly oblate with a degree of anisotropy usually between 1.2 and 1.4. As far as we know, such a strong effect has never been reported. In sandstone with detrital hematite as the main carrier, the degree of the induced AMS fabric is less than 1.02 suggesting that the ilmenite content in the metamorphic hematite is the main cause of the large observed field induced fabric in these rocks.

 
Centre-pivot irrigation system design for uniform water application rate
Authors: Baiamonte Giorgio , Elfahl Mustafa , Provenzano Giuseppe
Published: March 2020

In the last few decades, the use of centre-pivot irrigation systems has significantly increased, since it makes farming easier, is more efficient and less time-consuming compared to the other irrigation systems. Several studies have been focused on the hydraulics of the centre-pivot systems. Standard high-pressure impact sprinklers or low-pressure spray sprinklers or Low Energy Precision Application (LEPA) systems are generally mounted on the pipeline.

To ensure the uniformity of water application, the centre-pivot design requires increasing the flow rates along the lateral, because the sprinklers farther from the pivot move faster, and therefore their instantaneous application rates must be greater. Thus, the irrigated area under a centre-pivot system expands substantially with increasing system length. To irrigate the increased area by maintaining constant the application intensity, the manufacturers propose: i) to increase the flow rates of equally spaced sprinklers, ii) to gradually decrease the spacing of equal-flow sprinklers along the centre-pivot lateral, and iii) to use semi-uniform spacing, which is a combination of the first two methods.

However, the most common centre-pivot systems have equally spaced sprinklers with increasing flow rates (nozzle sizes) along the lateral, which is probably the easiest method from a practical point of view. Although many definitions and design procedures can be found in the technical literature, a universally accepted design procedure has not yet been found. In fact, the issue of centre-pivot irrigation system design is widely debated and there is still a need for simple, yet adaptive designing guidelines for farmers using these systems, specifically to maximize water use efficiency.

This study presents an alternative design procedure of centre-pivot irrigation system allowing to set favourable water application rates. First, the sprinklers’ spacing distribution corresponding to a fixed irrigated area along the radial direction is derived. According to this outcome, the results showed that sprinkler characteristics and/or pipe diameter need to be varied along the lateral, based on the desired and uniform water application rate. Then, for a practical case, an application based on the proposed hydraulic design procedure was performed and discussed.
Earth Observation services for Wild Fisheries, Oystergrounds Restoration and Bivalve Mariculture along European Coasts*
Authors: Rodriguez Galvez Luis , El Serafy Ghada , Wanke Sonja , Twigt Daniel , Villars Nicky
Published: March 2020

Sea related activities are set to increase and the growth in food production from sea enhancing global food security is already a reality. However, this growth must be aligned with increasing environmental constraints as well as complying and restoring regulations and frameworks. This requires the adoption of improved and efficient behaviors based on wider incorporation of available information and knowledge from the industry and citizens alike. Marine and coastal managers must make decisions to maintain the social, economic, and ecological health of marine and coastal areas in coastal and nearshore areas and to operate, plan and manage their activities at sea. The European funded FORCAST project represents a step forward in this direction by bringing the coastal water quality and met-ocean information closer to the target sectors: wild fisheries, oystergrounds restoration, and bivalve mariculture. FORCOAST will develop, test and demonstrate, in operational mode, novel Copernicus-based downstream information services that will incorporate and combine Copernicus Marine Environment Monitoring Service (CMEMS), Copernicus Land Monitoring Service (CLMS) and Climate Change Monitoring Service (CMS), local monitoring data and advanced modelling in the service. FORCOAST will provide consistent high resolution data products for coastal applications, based on a standardized data processing scheme. Furthermore, FORCOAST will make use DIAS which will help to develop the data access and cloud processing service. FORCOAST will provide those services in eight pilot service uptake sites covering five different regional waters (North Sea, Baltic Sea, Mediterranean Sea, Black Sea and the coastal Atlantic Ocean). The outcome of FORCAST is a novel commercial service that will provide Copernicus-based downstream information coastal services to a variety of stakeholders, which will result in an operation, planning and management improvement of different marine activities in the sectors of wild fisheries and aquaculture, having an economic and societal positive effect on the involved parties.

*This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870465
Detection of extreme events with IASI observations
Authors: Vu Van Adrien , Boynard Anne , Prunet Pascal , Jolivet Dominique , Lezeaux Olivier , Henry Patrice , Camy-Peyret Claude , Clerbaux Cathy
Published: March 2020

The 3 IASI instruments on-board the Metop satellites have been sounding the atmospheric composition since 2006. Up to ~30 atmospheric gases can be measured from IASI spectra, allowing monitoring of weather, atmospheric chemistry, and climate.

Extreme events such as fires, high pollution episodes, volcanic eruptions, industrial accidents, etc., that impact on the population and the environment have become a major political issue. With IASI providing global observations twice a day in near real time, a new way for the systematic and continuous detection of exceptional atmospheric events to support operational decisions is possible.

In this work, we explore and improve an automatic system for the detection and characterization of extreme events, which relies on the principal component analysis (PCA) method. We assess this PCA-based system by analysing IASI raw and compressed spectra along with their differences (residuals) for various past and documented extreme events. The benefits and limitations of this method will be discussed. A new method based on the refined analysis of residuals for the whole year 2019 is proposed, that could be used as an automatic detection method for unexpected events. Finally, we investigate the potential of deep learning methods as a way to compare residuals with a database of extreme event in order to better characterize detected events.
Operational Validation of Space-based Albedo Products from Upscaled Tower-based Albedometer Measurements
Authors: Song Rui , Muller Jan-Peter
Published: March 2020

Surface albedo is a fundamental radiative parameter which controls the Earth’s energy budget by determining the amount of solar radiation which is either absorbed by the surface or reflected back to atmosphere. Satellite observations have long been used to capture the temporal and spatial variations of surface albedo because of their repeated global coverage. In this work, a new method of upscaling surface albedo from ground level footprints of a few tens of metres to coarse satellite scales (≈1km) is reported [1]. Tower-mounted albedometer measurements are upscaled and used to validate global space-based albedo products, including Copernicus Global Land Service (CGLS) 1km albedo data (from Proba-V and previously form VEGETATION-2), MODerate resolution Imaging Spectroradiometer (MODIS) 500m albedo data, and Multi-angle Imaging SpectroRadiometer (MISR) 1.1km albedo data. MODIS albedo retrievals show the closest agreement with tower measurements, followed by the MISR retrievals, and then followed by the CGLS retrievals. The upscaling method uses high-resolution surface reflectance retrievals (from Landsat-8, Sentinel-2) to fill the spatial gaps between the albedometer’s field-of-view (FoV) and coarse satellite scales. High-resolution surface albedo products are generated by combining high-resolution surface reflectance data and MODIS bi-directional reflectance distribution function (BRDF) climatology data. This upscaling framework also uses a novel Sensor Invariant Atmospheric Correction (SIAC) method [2] to improve the accuracy of upscaled tower albedo values. Total uncertainties of upscaled albedo products are estimated by considering uncertainties from both the tower albedometer raw measurements and SIAC atmospheric corrections. This surface albedo upscaling method can be used over both heterogenous and homogenous land surfaces, and has been examined at the SURFRAD, BSRN and FLUXNET tower sites.

Keywords: surface albedo, upscale, CGLS, MODIS, MISR, SIAC

[1] Song, R.; Muller, J.-P.; Kharbouche, S.; Woodgate, W. Intercomparison of Surface Albedo Retrievals from MISR, MODIS, CGLS Using Tower and Upscaled Tower Measurements. Remote Sens. 2019, 11, 644, doi:10.3390/rs11060644.

[2] Yin, F., Lewis, P. E., Gomez-Dans, J., & Wu, Q. A sensor-invariant atmospheric correction method: application to Sentinel-2/MSI and Landsat 8/OLI. EarthArXiv 2019, https://doi.org/10.31223/osf.io/ps957.
The value of tidal-stream energy resource to off-grid communities
Authors: Lewis Matt , Maskell John , Coles Daniel , Ridgill Michael , Neill Simon
Published: March 2020

Tidal-stream energy research has often focused on the applicability of the resource to large electricity distribution networks, or reducing costs so it can compete with other renewables (such as offshore wind). Here we explore how tidal electricity may be worth the additional cost, as the quality and predictability of the electricity could be advantageous – especially to remote “off-grid” communities and industry.

The regular motion from astronomical forces allows the tide to be predicted far into the future, and therefore idealised scenarios of phasing tidal electricity supply to demand can be explored. A normalised tidal-stream turbine power curve, developed from published data on 15 devices, was developed. Tidal harmonics of a region, based on ocean model output, were used in conjunction with this normalised tidal-stream power curve, and predictions of yield and the timing of electricity supply were made. Such analysis allows the type and number of turbines needed for a specific community requirement, as well as a resource-led tidal turbine optimisation for a region. For example, with a simple M2 tide (12.42hour period) of 2m/s peak flow, which represents mean flow conditions, a rated turbine speed of 1.8m/s gives the highest yield-density of all likely turbine configurations (i.e. calculated from power density and so ignores turbine diameter), and with a 41% Capacity Factor. Furthermore, as tidal current and power predictions can be made, we explore the battery size needed for a given electricity demand timeseries (e.g. baseload, or offshore aquaculture). Our analysis finds tidal-stream energy could be much more useful than other forms of renewable energy to off-grid communities due to the predictability and persistence of the electricity supply. Moreover, our standardised power curve method will facilitate technical tidal energy resource assessment for any region.
Comparison of properties of the solar wind helium component close to the Sun and at 1 AU
Authors: Durovcova Tereza ,   PSP
Published: March 2020

The relative helium abundance (AHe) and alpha-proton relative drift often serve as one of the solar wind source identifiers. However, observations at 1 AU suggest that these relative properties may be affected by the interaction of different solar wind streams. Since the influence of stream interaction is reduced near the Sun, a comparison of observations at 1 AU and close to the Sun could help to reveal the processes which lead to AHe variations. In-situ measurements near the Sun are provided by the SWEAP instrument onboard Parker Solar Probe. It consists of electrostatic analyzers (SPANs) and the Faraday cup (SPC). SPAN-Ai measures the 3-D ion distribution from the shadowed region behind the spacecraft thermal shield and is equipped with a mass-to-charge detection. SPC is directed to the Sun and provides fast measurements of the ion reduced distribution function (RDF) as a function of energy/charge. We develop a new data analysis technique for computations of the proton and helium parameters from the RDFs measured by SPC and compare it with SPAN observations. Then, we combine the PSP measurements with observations at 1 AU and focus on variations of the helium properties. Finally, we discuss the connection between AHe variations and changes of the solar wind source region.
On the influence of climate and land use change on monthly baseflow across the U.S. Midwest
Authors: Ayers Jessica , Villarini Gabriele , Schilling Keith , Jones Chris
Published: March 2020

This study examines the role played by changes in the climate system and land use in the observed monthly baseflow records (1966-2015) for 458 U. S. Geological Survey sites across the U.S. Midwest. We developed parsimonious statistical models in which monthly baseflow is related to any combination of four predictors (precipitation, temperature, antecedent wetness, and agriculture). We found that precipitation and antecedent wetness were the strongest predictors for all months, pointing to the role of water availability and infiltration in driving baseflow. Temperature was an important factor in the winter and spring where snow-melt processes are the most relevant. Agriculture was selected in the Corn Belt region during the growing season (from April to August) indicating that corn and soybean production in the Midwest promote baseflow discharge to streams. Overall, the goodness-of-fit for our models and cross validation strongly support our modeling results for all months. Differences in model selection reported here can aid water managers in decision making for water availability, food security and economic growth.
Hydrogeochemical anomalies associated with the 2017 MW 5.5 Pohang earthquake in South Korea
Authors: Kim Jaeyeon , Lee Kang-Kun
Published: March 2020

The 2017 MW 5.5 Pohang earthquakes, which were known as triggered by enhanced geothermal system (EGS) stimulations, had significant effects on the groundwater system. This study aimed to identify the hydrogeochemical anomalies and to understand the response mechanisms of groundwater system to the earthquake. For this, the environmental isotopes (222Rn, Sr, 2H, and 18O), major ions, and time-series data (groundwater level, temperature, and electrical conductivity) were analyzed. Principal component analysis (PCA) was also employed. The results from time-series data showed the anomalies in the groundwater wells located near the epicenter. The hydrochemical parameters including stable isotopes data of 2H and 18O showed the different change patterns among groundwater wells before/after the earthquakes, which were related to the distance from epicenter, faults, and seawater. The environmental isotopes, radon and strontium, suggested the possible mechanisms underlying the effects of earthquakes by spatial distributions, such as seawater intrusion, water-rock interactions, shallow and deep aquifer mixing, deep fluid upwelling, and bedrock fracture opening. With this, the main cluster of PCA results was also distributed along these isotope concentration gradients.

Our findings proved the usefulness of environmental isotopes and hydrogeochemical parameters to understand the earthquake-related changes in groundwater system. These studied parameters and the adopted methods would be positively applied for other earthquake zones.
Improving the understanding of recharge in a basalt aquifer based on a soil moisture model, water levels and climatic data
Authors: Gurieff Lisa Bagger , Reading Lucy
Published: March 2020

Knowledge of recharge processes in groundwater resource areas is of great importance for developing sustainable water management plans. In an effort to enhance the understanding of recharge in a basalt aquifer, a national water balance soil moisture model was compared with the response in water tables in multiple private pumping bores across the Tamborine Mountain plateau located in South East Queensland, Australia. The water levels in the pumping bores were influenced by the everyday use of the bores, which are utilised for household supply, stock watering, garden watering and irrigation. In each bore, the pumping response was identified and filtered out before being compared to the soil moisture model results. The soil moisture model (AWRA-L Australian Water Resource Assessment Landscape) includes results of surface runoff, soil moisture, evapotranspiration and deep drainage, to a depth of 6 m. The simulated soil moisture levels in the rootzone (rootzone defined as depth between 0 - 1 m), showed a similar hydrographic response following rain events to that observed in water levels in the aquifer. The response in the aquifer compared to the soil moisture showed some of the deeper bores had a lag effect and furthermore, the response also showed dependency on the soil moisture level (%) and on the size/duration of the rain event. It was observed that the simulated deep drainage (recharge) did not correlate to the observed changes in water tables. The soil moisture model simulated a nearly constant deep drainage (recharge) of 0.05±0.01mm a day, whereas the bores showed large increases in water table in response to rainfall events. Previous studies in the area based on the chloride mass balance approach have estimated that the annual deep drainage volume was an average of 30% of annual rainfall, while the soil moisture model approach has simulated an annual deep drainage volume of 1.2 – 1.7% of the total annual rainfall. While these results show that there are shortcomings related to applying the soil moisture model to estimate aquifer recharge, these results are an important initial finding regarding the estimation of recharge in the study area and can be used in water balance calculations for water management purposes. With further research into the observed relationships and parameterisation of these relationships, the soil moisture model could be updated to better represent recharge within this, and similar, study areas.
The impact of an eastward traveling cut-off low on tropospheric composition and the formation of a river of smoke: a case from AEROCLO-sA
Authors: Flamant Cyrille , Gaetani Marco , Chaboureau Jean-Pierre , Chazette Patrick , Formenti Paola
Published: March 2020

We investigate the impact of an eastward moving cut-off low (CoL) on the formation of a river of smoke as well as on the vertical distribution of biomass burning aerosols (BBAs) in the troposphere during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign in September 2017. The CoL developed in the westerlies over the Southeast Atlantic Ocean and advected over southern Africa between 1 and 6 September 2017. Northern Namibia, were most of the AEROCLO-sA related operations took place, was under the influence of a well formed, stationary, isolated CoL on 3 and 4 September. Subsequently, the fast evolving CoL travelled south-eastward over South Africa between 5 and 6 September before merging back with the main westerly flow. Based on the use of a tailored complementary suite of global and mesoscale numerical simulations as well as ground-based, airborne and space-borne observations of the atmospheric dynamics, thermodynamics and composition, the picture emerges that the characteristics of the river of smoke (timing, vertical extent of the BBA layer) are very much tied to the later (fast evolving) stage of the evolution of the CoL than the earlier (stationary) stage.  The mechanisms by which the CoL observed over southern Africa influences the vertical structure of the BBA layer is essentially through the ascending (descending) motion above the BBA layer to the northeast (southwest) of the CoL center. In the presence of the CoL, the top of the BBA layer over northern Namibia was found to reach attitudes in excess of 8 km AMSL. This is much higher that the height of the top of the BBA layer over the regions where the smoke originated from (Angola, Zambia, Zimbabwe, Mozambic) which was between 4 and 5 km AMSL. Also, the CoL favored the formation of mid-level clouds near the top of the BBA layer. Mid-level clouds were embedded in the river of smoke that were related to the circulation and ascending motions in the lee of the CoL.
Comparison of Practice Factor Values of Soil and Water Conservation Measures Under the Condition of Snowmelt and Rainfall Erosion
Authors: Xu Xiu Quan , Fan Hao Ming , Tan Juan , Jia Yanfeng , Wu Min
Published: March 2020

The benefits of soil and water conservation measures during snowmelt process is rarely studied in Northeast China. Based on the observation results of snowmelt erosion of Jixing runoff plots (Meihekou City, Jilin Province)in spring in 2015 and 2016, combined with the previous results of rainfall erosion, the practice factor values of soil and water conservation measures, the numbers of soil erosion events, the runoff depth and erosion modulus between snowmelt and rainfall conditions were compared to investigate the difference of effects of the soil and water conservation measures on snowmelt and rainfall erosion. The results show that the practice factor values range from 0.001 to 0.46, while the best measure for prevention of snowmelt erosion is the ecological restoration measure, with the characteristics of shorter period, less amount of snowmelt runoff. The effect of the cut-off drain measure, a typical engineering measures, on snowmelt erosion is mainly controlling the amount of snowmelt runoff. The erosion modulus and runoff depth of the shrub ridging are larger compared with the contour ridge and furrow planting, another kind of tillage measure, under snowmelt condition. Both two types of soil erosion, namely snowmelt and rainfall erosion, should be taken into account in planning and design of soil and water conservation measures in areas with snowmelt erosion, especially for the cultivated land.
Centennial-scale evolution of methane during the penultimate deglaciation
Authors: Schmidely Loïc , Silva Lucas , Nehrbass-Ahles Christoph , Han Juhyeong , Shin Jinhwa , Schmitt Jochen , Fischer Hubertus , Stocker Thomas
Published: March 2020

 Small air inclusions in ice cores represent a direct archive of past atmospheric compositions, allowing us to measure the concentration of the three most potent non-condensable Greenhouse Gases (GHG) CO2, CH4 and N2O as far back as 800,000 years before present (kyr BP). These records demonstrate that transitions from glacial to interglacial conditions are accompanied by a substantial net increase of CO2, CH4 and N2O in the atmosphere (Lüthi et al. 2008, Loulergue et al. 2008, Schilt et al. 2010). A sound understanding of the interplay between the reorganization of the climate system and the perturbation of GHG inventories during glacial terminations is partly limited by the temporal resolution of the records derived from ice cores. In fact, with the exception of the last deglaciation (23-9 kyr BP) centennial-scale GHG variability remained uncaptured for precedings glacial terminations.

In this work, we exploit the exceptionally long temporal coverage of the EPICA Dome C (EDC) ice core to reconstruct, for the first time, centennial-scale fluctuations of CH4 mole fractions from 145 to 125 kyr BP, encompassing the entire penultimate deglaciation (138-128 kyr BP). With a temporal resolution of ~100 years, our new record is now unveiling all climate-driven signals enclosed into the EDC ice core, exploiting the maximum resolution possible at Dome C (). This offers us the opportunity to study the timing and rates of change of CH4 in unprecedented details.

Preliminary analysis reveals that the deglacial CH4 rise is a superimposition of gradual millennial-scale increases (~0.01-0.02 ppb/year) and abrupt and partly intermittent centennial-scale events (~80-200 ppb in less than a millennium). We will investigate processes modulating the observed changes in the CH4 cycle, compare the structure of our record with the CH4 profile of the last deglaciation (Marcott, 2014) and contrast it with the EDC CO2 and N2O records over the penultimate glacial termination now available in similar resolution.
Creating a 4D SO2 dataset with high vertical resolution by connecting volcanic cloud observations through trajectory modelling
Authors: Sandvik Oscar S. , Martinsson Bengt G. , Friberg Johan , Sporre Moa
Published: March 2020

After major volcanic eruptions, sulphur dioxide (SO2) can be released in large quantities to the stratosphere. The sulphur dioxide is later oxidised into sulphate aerosol which reflect incoming sunlight and cools the surface temperatures around the globe. The duration length is highly dependent on the altitude of the SO2 cloud and its geographical location. Today, infrared sensors on-board satellites can give an estimate of the SO2 cloud top height and lidar instruments can give height profiles in their narrow field-of-view. Both these classes of instrument lack the capability to fully map the vertical distribution of the SO2 clouds. We propose a scheme to create a SO2 dataset with high vertical resolution. The scheme consists of distributing SO2 column densities from ultra-violet and infrared satellite instruments into SO2 profiles using scattering data from the CALIOP lidar on-board the CALIPSO satellite. The CALIOP lidar has a vertical resolution of up to 60 m in the region of interest. Since CALIOP only collect data along narrow fields-of-view, this initially gives us the SO2 dataset only where CALIOP has collected data. To make the most of this information we run the FLEXPART trajectory model. If air parcels that were initially in CALIOP’s field-of-view and later in another part of the SO2 cloud, then the output from FLEXPART gives us this information. Thus, from CALIOP we shift the vertical information in time to other parts of the SO2 cloud using the trajectory model.