bluuebunny/crossref_metadata_2025 huggingface dataset:
First global evaluation of the representation of water uptake within ten earth system models
Authors: Burgos Simón Maria Ángeles ,   Aerosol hygroscopicity - model evaluation team
Published: March 2020

Aerosol optical properties, such as particle light scattering, depend on the particle size and chemical composition, which in turn are affected by the particle’s ability to take up water. Thus, particle hygroscopic growth will have an impact on the optical properties and in turn will affect the aerosol-radiation interaction and the calculations of the Earth’s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor f(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.

In our previous work (Burgos et al., 2019), we carried out a standardized analysis of scattering in-situ measurements at 26 sites around the globe, creating a benchmark dataset (open access via EBAS, http://ebas.nilu.no/). The project continues with the present work, which is part of the AeroCom phase III INSITU project: Evaluation of hygroscopicity of aerosol optical properties. Here, we present a comprehensive model-measurement evaluation of f(RH) for ten different earth system models. Modelled and measured scattering enhancement factors are compared for 22 sites, representative of Arctic, marine, rural, mountain, urban and desert aerosols.

Overall, a large variability and diversity in the magnitude of predicted f(RH) amongst the models is found and the modelled f(RH) tends to be overestimated relative to the measurement values. This difference cannot be explained by the aerosol type. Agreement between models and measurements was strongly influenced by the choice of RHref. Models show a significantly larger discrepancy with the observations if model dry conditions are set to RH=0% instead of RH=40%. Model parameterizations of aerosol hygroscopicity and mixing state may be driving the observed diversity among models as well as the discrepancy with measurements. Measurement conditions have to be considered in this type of evaluation, specifically the fact that “dry” measurements may not be “dry” in model terms.

This work has been submitted to ACPD.

Burgos, M., Andrews, E., Titos, G., Alados-Arboledas, L., Baltensperger, U., Day, D., Jefferson, A., Kalivitis, N., Mihalopoulos, N., Sherman, J., Sun, J., Weingartner, E., and Zieger, P.: A global view on the effect of water uptake on aerosol particle light scattering, Scientific Data, 6, https://doi.org/10.1038/s41597-019-0158-7, 2019.
Tidal Forcing as a Trigger of Arctic Ice Stream Deglaciation
Authors: Velay-Vitow Jesse , Peltier Richard
Published: March 2020

It has been established recently (Velay-Vitow, Peltier and Stuhne JGR-Oceans 2019) that a high amplitude M2 tide may have triggered and contributed to the forcing of the rapid deglaciations of the Hudson Strait ice stream, commonly referred to as Heinrich events, during the last glacial period. The required conditions for a tidally triggered marine terminating ice stream instability are an ice stream with a retrograde slope of the ice stream bed at the edge of an ice sheet and high amplitude tides coincidental with the grounding line. Two paleo ice streams in the Arctic, the Amundsen Gulf ice stream and the McClure ice stream may have been amenable to rapid deglaciation prior to and during Younger Dryas time, as these locations may have been characterized by the required bathymetric conditions. Additionally, it has been shown in Griffiths and Peltier (GRL 2008) that the Arctic was megatidal at last glacial maximum. We investigate the possibility that some combination of the previously mentioned ice streams were rendered unstable by high amplitude polar tides, and proceeded to rapidly deglaciate, disgorging icebergs and ice rafted debris into the Arctic ocean. We further examine the effect that these proposed ice stream instabilities would have had on the tidal regime in the Arctic, and, by the mechanism of glacial isostatic adjustment, upon the underlying Arctic bathymetry.
Application of hyperspectral remote sensing in the longwave infrared region technology for assessing the influence of settled desert dust particles on soil surface
Authors: Ben Dor Eyal , Notesko Gila , Weksler Shahar
Published: March 2020

Soil mineralogy holds important information on the soil origin and development. Most common minerals in soils—quartz, clay minerals and carbonates—present fundamental spectral features in the longwave infrared (LWIR) region (8.0–12 μm range), whereas quartz is featureless in the optical region (0.4–2.5 μm range). A procedure for determining the soil surface mineralogy from hyperspectral LWIR data was used to assess the interaction with desert dust particles that accumulate on the soil surface during dust storms. Ground- and field-based hyperspectral LWIR images of different types of Israeli soils, before and after dispersion of desert dust-like material on the surface, were acquired with the Telops Hyper-Cam sensor, to calculate the surface emissivity spectra of soils, representing the surface mineralogy. Identifying mineral-related emissivity features and calculating their relative intensities, using two created indices―SQCMI (Soil Quartz Clay Mineral Index) and SCI (Soil Carbonate Index)―enabled determining the content of quartz, clay minerals, and carbonates in the soil in a semi-quantitative manner—from more to less abundant, and identifying changes in their abundance resulting from the dispersion of dust on the surface. The dust affected the mineral-related spectral features of the soil surface, depending on the mineral composition of the dust compared to soil surface mineralogy, and its amount. The ability to detect minor mineralogical changes on the soil surface using high spectral resolution LWIR data was demonstrated.
The evolution of the Patagonian Ice Sheet from 35 ka to the Present Day (PATICE)
Authors: Davies Bethan ,   PATICE Team
Published: March 2020

We present PATICE, a GIS database of Patagonian glacial geomorphology and recalibrated chronostratigraphic data. PATICE includes 58,823 landforms and 1,669 ages, and extends from 38°S to 55°S in southern South America. We use these data to generate new empirical reconstructions of the Patagonian Ice Sheet (PIS) and subsequent ice masses and ice-dammed palaeolakes at 35 ka, 30 ka, 25 ka, 20 ka, 15 ka, 13 ka (synchronous with the Antarctic Cold Reversal), 10 ka, 5 ka, 0.2 ka (synchronous with the “Little Ice Age”) and 2011 AD. At 35 ka, the PIS covered of 492.6 x103 km2, had a sea level equivalent of ~1,496 mm, was 350 km wide and 2090 km long, and was grounded on the Pacific continental shelf edge. Outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams. The PIS reached its maximum extent at 33 – 28 ka from 38°S to 48°S, and earlier, around 47 ka from 48°S southwards. Net retreat from maximum positions began by 25 ka, with ice-marginal stabilisation at 21 – 18 ka, followed by rapid deglaciation. By 15 ka, the PIS had separated into disparate ice masses, draining into large ice-dammed lakes along the eastern margin, which strongly influenced rates of recession. Glacial readvances or stabilisations occurred at 14 – 13 ka, 11 ka, 5 – 6 ka, 1 – 2 ka, and 0.2 ka. We suggest that 20th century glacial recession is occurring faster than at any time documented during the Holocene. 
ROMEO - ROmanian Methane Emissions from Oil and Gas
Authors: Röckmann Thomas ,   The ROMEO team
Published: March 2020

According to UNFCCC statistics, in 2015 Romania was the country in the European Union that reported the highest emissions of CH4 from the oil and gas sector to the atmosphere, in particular related to methane production and end use. Limiting these oil and gas-related emissions could provide an attractive greenhouse gas emission reduction target for the EU. However, the reported estimates are derived using standard emission factors and there are only very few observations which investigate whether the reported emissions are realistic. The ROMEO project was designed to provide experimental quantification of methane emissions from the oil and gas sector in Romania. This may strengthen the scientific basis for establishing effective emission mitigation measures. ROMEO is part of the international Climate and Clean Air Coalition's (CCAC's) Methane Science Studies. In August 2019, the first  phase of ROMEO was a city campaign in Bucharest and Ploiesti, where methane emissions were quantified at the street level, using three vehicles. Source attribution was carried out by isotopic analysis and measurement of the ethane-methane ratio. The main ROMEO campaign took place in October 2019, using as campaign base the Strejnicu airfield near Ploiesti. Eight ground measurement teams visited more than 1000 individual facilities and performed methane measurements by stationary and mobile measurements from vehicles, using tracer release approaches and by plume mapping from drones. Very low wind speeds during the campaign period made emission quantification challenging, but about 200 quantifications were attempted. An optical gas imaging team visited many facilities in order to investigate the origin of the emissions at the component scale. Our project partner OMV-Petrom provided information on the facilities and site access where needed. Sites for emissions quantification were selected independent of the operator. To connect the facility scale to the regional scale, two research aircraft from INCAS and Scientific Aviation Inc. performed more than 20 research flights to identify and quantify methane emissions from individual facilities, facility clusters and extended regions. Ground-based in situ and total column measurements provide additional information on the background levels of CH4. Various models are used for emission quantification, from plume dispersion and mass balance models for individual facilities to atmospheric chemistry and transport models for interpretation of the larger scale aircraft measurements. The final goal of ROMEO is to provide a combined bottom-up and top-down approach to quantify CH4 emissions related to oil and gas exploration, natural gas distribution and gas use from Romania. I will present the overall setup of the ROMEO project, interesting examples from individual facilities and preliminary results from ground and airborne measurements.
The observed properties of summer convective clouds and precipitation over the central Tibetan Plateau
Authors: Chang Yi , Guo Xueliang , Tang Jie , Lu Guangxian , Qi Peng
Published: March 2020

Macro- and micro-physical properties of summer convective clouds and precipitation over the central Tibetan Plateau (TP) were investigated using the in-situ observations during the Third Tibetan Plateau Atmospheric Sciences Experiment (TIPEX-Ⅲ) in 2014. The advanced aircraft and radar observational systems were employed during the experiment.
Results show that the convective events over the central TP were characterized as frequently weak precipitation with a significant daily variation. The convections were generally initiated in the late morning and peaked in the late afternoon, and the convective clouds were turned into stratiform clouds in the nighttime. The average heights of cloud top and cloud base were 11.62 ± 2.45 km and 6.89 ± 1.58 km, respectively. The average rain rate was ≈ 1.2 mm/h, and compared to M-P distribution, the Γ distribution was more suitable in describing the raindrop size distribution of precipitation over the central TP.
Aircraft observations show that the clouds over the central TP were normally in a mixed-phase state, and had lower concentrations of cloud particles and weaker updraft, but more larger particles than over plains. The particle size distributions (PSDs) of cloud droplets were mainly bimodal, and the large cloud particles (> 50 μm) had an exponential PSD type. The aircraft observed convective clouds were mainly singular newly born or developing convective cells, in which ice processes happened at early stage, quick and massive glaciation happened at higher altitude, coalescence and rimming contributed to the formation of precipitation.
The Use of Landsat 8 and Sentinel-2 Time Series Data for Monitoring Drought, Chlorophyll-a and Turbidity in Lake Chad
Authors: Lee Sang Il , Buma Willibroad Gabila
Published: March 2020

A decline in Lake Chad’s water level has been observed for over two decades. With millions of people relying on the lake, and considering its dynamic behavior, methods for the continuous and spatially distributed retrieval of water quantity and quality parameters are vital for proper monitoring and management initiatives. Here, we propose an integrated approach for drought, chlorophyll-a (Chl-a) and turbidity monitoring in Lake Chad using satellite datasets.

First, we used remote sensing information to constrain drought patterns over the immediate lake environment. Vegetation conditions within and around the lake was used to assess drought conditions in this area. Using Landsat multispectral images obtained between 1999 and 2018, Vegetation Temperature Condition Index (VTCI) was derived and used as an indicator for drought monitoring. Vegetation proportion from WorldView-03 images was used to evaluate the accuracy of methods used to derive VTCI. Obtained results showed that most areas experienced mild drought conditions.

Secondly, we assessed the performance of band algorithms in estimating Chl-a concentrations and turbidity levels from Landsat-8 and Sentinel-2A and 2B images. A two-band semi-analytical Chl-a and turbidity retrieval model was used for estimating the Chl-a concentrations and turbidity levels between 2015 and 2019. Due to the absence of in-situ data, estimates from the extraction models were statistically compared with datasets obtained from WorldView-03. Further inter-comparison of Chl-a and turbidity retrieved from the two sensors was carried out.

This study shows how satellite observations can be used to complement sparse and declining in situ drought, Chl-a and turbidity monitoring networks in this area. Solidifying the importance of remote sensing in areas that are difficult to access or with poor availability of conventional data sources.
Making Use and Sense of 75,000 Forecasts of the Sea Ice Drift Forecast Experiment (SIDFEx)
Authors: Goessling Helge F. ,   SIDFEx Team
Published: March 2020

The Sea Ice Drift Forecast Experiment (SIDFEx) is a Year of Polar Prediction (YOPP) community effort to solicit, collect, and analyze sea ice drift forecasts, based on various methods, on a regular basis. SIDFEx is inspired by research and operational needs to forecast future positions of assets drifting in Arctic sea ice. Beside a number of sea-ice buoys of the International Arctic Buoy Programme, current targets include the MOSAiC drift campaign main site (and distributed network) for which consensus forecasts are delivered every six hours. A systematic assessment of real drift forecasting capabilities across operational and research forecast systems is meant to improve our physical understanding of sea ice and to identify and resolve model shortcomings.

Since the launch of SIDFEx in 2017, thirteen groups have started contributing drift forecasts to SIDFEx on a regular basis. Most groups derive their 2-days to seasonal-range forecasts by means of diagnostic tracking based on prediction drift fields of coupled or uncoupled general circulation models. Some groups submit ensembles of drift trajectories instead of single (deterministic) trajectories, and several groups submit their forecasts in real-time. We present results from around 75,000 individual forecasts, how they have been used for real-time support of the MOSAiC Arctic drift campaign since autumn 2019, and what they reveal about current models' capabilities to forecast sea-ice drift and deformation.
Unusual location of the geotail magnetopause at lunar distance: ARTEMIS observation
Authors: Shang Wensai , Tang Binbin , Shi Quanqi , Tian Anmin , Zhou Xiaoyan , Yao Zhonghua , Degeling Alex W. , Rae Iain Jonathan , Fu Suiyan , Lu Jianyong , Pu Zuyin , Fazakerley Andrew N. , Dunlop Malcolm M. , Facsko Gabor , Liu Jiang , Wang Ming
Published: March 2020

The Earth’s magnetopause is highly variable in location and shape, and is modulated by solar wind conditions. On 8 March 2012, the ARTEMIS probes were located near the tail current sheet when an interplanetary shock arrived under northward interplanetary magnetic field (IMF) conditions, and recorded an abrupt tail compression at ~(-60, 0, -5) RE in Geocentric Solar Ecliptic (GSE) coordinate in the deep magnetotail. Approximately 10 minutes later, the probes crossed the magnetopause many times within an hour after the oblique interplanetary shock passed by. The solar wind velocity vector downstream from the shock was not directed along the Sun-Earth line, but had a significant Y component. We propose that the compressed tail was pushed aside by the appreciable solar wind flow in the Y direction. Using a virtual spacecraft in a global magnetohydrodynamic (MHD) simulation, we reproduce the sequence of magnetopause crossings in the X-Y plane observed by ARTEMIS probes under oblique shock conditions, demonstrating that the compressed magnetopause is sharply deflected at lunar distances in response to the shock and solar wind VY effects. The results of the two different global MHD simulations show that the shocked magnetotail at lunar distances is mainly controlled by the solar wind direction with a timescale of about a quarter hour, which appears to be consistent with the windsock effect. The results also provide some references for investigating interactions between the solar wind/magnetosheath and lunar nearside surface during full moon time intervals, which should not happen in general.
The rain-shadow effect for the Ethiopian Highlands
Authors: Van Schaeybroeck Bert , Van den Hende Céline , Nyssen Jan , Van Vooren Sander , Van Ginderachter Michiel , Termonia Piet
Published: March 2020

Recent work highlight the ambiguities in the definition and difficulties in quantification of the rain shadow effect. According to this phenomenon  there is a reduced rainfall on the leeward side of the mountains as compared to the windward side. We present a statistical approach to study this effect in case climatological time series of model data are available in geographically complex regions. Our approach requires only gridded rainfall, wind and  model elevation. We disentangle the aspects that contribute to the rainfall enhancement at the windward side. We apply the approach on the summer mountain precipitation (kerimt) over the Ethiopian Highlands based a new 21-year long climate run with the regional climate model ALARO-0 at a resolution of 4 km. There is an overall increased rainfall of 20% for windward events as compared to leeward events, but locally this can exceed 150%. This increase can be attributed to the positive differences between windward and leeward events in their frequency of occurrence, and, in the rainfall quantity during rainfall events. Differences in rainfall frequency, on the other hand, are spatially inhomogeneous and smaller than the spatial variations of the rainfall frequencies themselves.
AFRICAP - The impact of climate change on agriculture in Tanzania, Malawi, Zambia and South Africa
Authors: Chapman Sarah , Birch Cathryn , Pope Edward , Sallu Susannah , Bradshaw Catherine , Davie Jemma , Marsham John
Published: March 2020

Sub-Saharan Africa is one of the most food insecure regions in the world and is highly vulnerable to climate change. We use a comprehensive set of bias-corrected global (CMIP5) and regional (CORDEX-Africa) models and a new convection-permitting pan-Africa simulation (and its parameterized counterpart) to examine changes in rainfall and temperature and the impact on agricultural suitability of maize, cassava and soy in sub-Saharan Africa by 2100 (RCP8.5). This is the first time a convection-permitting projection has been used to examine agricultural suitability in Africa. Increasing temperatures and declining rainfall led to large parts of sub-Saharan Africa becoming unsuitable for multiple staple crops, which may necessitate a transition to more heat and drought resistant crops to ensure food and nutrition security. Soy was resilient to temperature increases, however maize and cassava were not, leading to declines in crop suitability. Inclusion of sensitivity to extreme temperatures led to larger declines in maize suitability than when this was excluded. The variation in rainfall projections within the multi-model ensemble was examined in detail for Tanzania, Malawi, Zambia and South Africa. In each country the range of projections included wetting and drying, but the majority of models projected rainfall declines, except in Tanzania, leading to declines in crop suitability. Overall, the CORDEX and CMIP5 models gave similar results for agricultural suitability. Explicit-convection led to more temperature extremes, but had little systematic impact on temperature and rainfall, and the resulting suitability analysis. Global model uncertainty, rather than convection parameterizations, still makes up the largest part of the uncertainty in future climate. Explicit-convection may have more impact if suitability included a more comprehensive treatment of extremes. This work highlights the key uncertainty from global climate projections for crop suitability projections, and the need for improved information on sensitivities of African crops to extremes, in order to give better predictions and make better use of the new generation of explicit-convection models.
Modelling constraints on rifting in the Afar region: the birth of a triple junction
Authors: Khalil Hany , Capitanio Fabio , Betts Peter , Cruden Alexander
Published: March 2020

Rifting in the Afar region is considered to be the only known example of the formation of an incipient divergent triple junction. Taking the Afar region as an example, we use three-dimensional (3D) laboratory experiments to test hypotheses for the formation and evolution of divergent triple junctions. We systematically evaluate the role of mechanical weakening due to plume impingement versus inherited weak linear structures in lithospheric mantle under both far-field orthogonal and rotational extensional boundary conditions. The interaction between far-field boundary forces and inherited rheological heterogeneities results in a range of complex rift propagation geometries and structural features, such as rift segmentation and ridge jumps, which are comparable to those observed in the Afar region. The combination of rotational boundary conditions and inherited linear heterogeneities favours the formation of rifts that connect at high-angles. Lithospheric weakening associated with a mantle plume triggers different rifting styles but has little influence on large-scale continental breakup. When compared to the Afar region, our results suggest that the rotation of the Arabian plate since the Oligocene led to rifting of the Red Sea and the Gulf of Aden, which are distinct from the formation of the Main Ethiopian Rift. We suggest that rifting in the Afar region is not consistent with the incipient divergent triple junction hypothesis. Rather, the Afar triple junction formed as a result of complex multi-phase rifting events driven by far-field tectonic forces.
Environmentally hardened, high-altitude, high-latitude seismic stations on Mt. Erebus, Antarctica
Authors: Beaudoin Bruce , Arnell Kirsten , Carpenter Paul , Lingutla Narendra , Meyers John , Nikolaus Kevin , Roth Aurora
Published: March 2020

The IRIS/PASSCAL Instrument Center is installing 5 seismic stations around the summit of Mt. Erebus, Antarctica. IRIS is funded by the National Science Foundation to install and maintain these stations long-term, a task undertaken by the Polar team at PASSCAL. The purpose of the network is to provide a baseline measurement of volcanic events and act as a fiducial array for future experiments. Each station’s instrument package comprises a data logger recording a broadband and strong-motion seismometer, and a separate data logger recording an infrasound sensor. Station state of health and near real-time data are transmitted via Iridium modems.

The Mt. Erebus network is installed between 2000 m and 3400 m elevation spaced around the volcano summit. This is a particularly harsh environment for operating autonomous seismic stations with extreme low temperatures and high winds. Station power systems need to have enough capacity to winter-over for roughly 6-months without recharge. Station enclosures need to provide sufficient insulation to keep the data logger within its temperature operating range.

To design these stations for long term, 365/24/7 operation, we leveraged proven station enclosure and power system designs developed over the last 12 years of PASSCAL engineering seismic systems for Antarctica. The Mt. Erebus station design is modular and standardized, separating the bulk of the power storage and electronics' enclosures, allowing for streamlined upgrades or additions without having to overhaul the entire station. Power for the system will rely on lead acid batteries and solar charging; forgoing higher efficiency primary lithium thionyl chloride batteries used elsewhere in Antarctica, to reduce long-term station costs.

Station health will be monitored at IRIS/PASSCAL and low sample rate (20 sps) broadband data will be captured in near-real time. Higher sample rate data are recorded locally and collected annually during the austral summer. All data will be available from the IRIS Data Management Center.
Terrestrial Biological Nitrogen Fixation in CMIP6 Models
Authors: Davies-Barnard Taraka , Meyerholt Johannes , Zaehle Sönke , Friedlingstein Pierre , Brovkin Victor , Fan Yuanchao , Fisher Rosie , Jones Chris , Lee Hanna , Peano Daniele , Smith Benjamin , Wårlind David , Wiltshire Andy , Ziehn Tilo
Published: March 2020

Biological nitrogen fixation (BNF) is a key contributor to sustaining the terrestrial carbon cycle, providing nitrogen input that plants require. This is particularly salient for projections of carbon uptake under increased atmospheric carbon dioxide concentrations, which may allow for so-called ‘carbon dioxide fertilisation’ if other plant requirements, such as nitrogen, do not prevent increases in productivity. The amount, processes, and global distribution of BNF is highly disputed and consequently land surface models represent it in varying ways. Looking at the latest generation of CMIP6 earth system models with terrestrial nitrogen cycles, we consider their performance with regard to BNF. We assess models against a new comprehensive meta-analysis of BNF field measurements that gives a global range and site-specific values. We find that compared to the wide range of upscaled observations, the models still have a larger range, with under and overestimates.
Soil erosion as pathway of microplastic transport from agricultural soils to inland waters
Authors: Pinheiro Machado Rehm Raphael , Fiener Peter
Published: March 2020

Agricultural soils play a key role as sink of microplastic (MP) coming from different sources, especially via the application of sewage sludge, compost, the decay of plastic mulch, and tire ware particles along streets. However, the effectiveness of this sink might be substantially reduced in areas subjected to water erosion. The aim of this study is to determine the transport potential of MP during water erosion events on agricultural land. More specifically, we are interested if MP is preferentially transported or if it is attached or associated to soil minerals and aggregates leading to a more conservative transport behavior. The transport behavior is studied based on a series of plot rainfall simulations on a silty loam (16% sand, 59% silt, 25% clay; 1.3% OC) and a loamy sand soil (72% sand, 18% silt, 10% clay; 0.9% OC) located at experimental farms in Southern Germany. To simulate heavy rain on dry and wet soil a sequence of two simulations with a gap of 30 min was performed for 30 min each (rainfall intensity 60 mm/h) on each of the four plots (2 m x 5 m). The simulations are repeated in spring and autumn for two years. Before the beginning of the experiment all plots were prepared, adding fine (53-100 μm) and coarse (250-300 μm) microplastic (high density polyethylene) in a topsoil (< 10 cm) concentration of 10 g/m-2 and 50 g m-2. The different soils show similar mean runoff rates for the dry run (2 l min-1), whereas the wet run produced slightly higher rates on the silty loam (5.5 l min-1) compared to the loamy sand soil (4 l min-1). In contrast, MP erosion and transport under the loamy sand was more selective, leading to MP enrichment for the first set of experiments of a factor of 3 to 20, compared to MP under silty loam with an enrichment factor of 0,4 to 0,8. The results from the first set of rainfall simulations clearly underlines the selective nature of MP erosion and transport leading to a disproportionate loss of MP from eroding sites into inland waters. The degree of MP enrichment in surface runoff is heavily depending on soil texture and especially moisture status at the beginning of an erosive rainfall event. Further investigations regarding more long-term MP enrichment effects depending on MP association to soil minerals and aggregates are under preparation.
Morphology of lava domes inferred from numerical modeling
Authors: Ismail-Zadeh Alik , Melnik Oleg , Tsepelev Igor
Published: March 2020

Several types of lava dome morphology can be distinguished depending on the flow rate and the rheology of magma. At an endogenous regime, magma is embedded inside the dome and fresh magma is not extruded on the surface; vice versa, at an exogenous regime, a fresh lava is extruded, and a lava obelisk is of particular interest. Sometimes obelisks reach hundreds of meters in height before they collapse. We present models of magma extrusion on the surface and lava dome evolution to analyze morphology of the domes. For this aim, we consider a flow of a Newtonian and non-Newtonian viscous inhomogeneous incompressible fluid in the field of gravity. The flow is described by the Navier-Stokes equations, the continuity equation, the transport equation of a two-component incompressible fluid, the heat conduction equation, and the rheological law. The lava viscosity in our models depends on the crystals concentration, temperature, and the rate of shear deformation. We show that the morphology of the domes depends on the characteristic time of crystal growths in the magma and on the rate of magma extrusion. In this case, obelisks are formed at a small value of the characteristic time of growth of crystals and/or low extrusion rates. At high values of the characteristic time and high extrusion rates, magma spreads over the surface after an eruption.
Magnetostratigraphy and Kinematic Characteristics of Datca Graben (Mugla, SW Turkey)
Authors: İnce Meryem Dilan , Kaymakcı Nuretdin , Sümer Ökmen , Uzel Bora , Şiş Seçkin , Tosun Levent , Langereis Cor , Stoica Marius
Published: March 2020

This study involves kinematic development and magnetostratigraphy of infill of the Datça Graben located at the southwesternmost corner of Anatolia (Turkey). The study comprises kinematic analysis based on fault slip data collected from the margins of the Datça Graben and the magnetostratigraphic analysis of infill of the Datça Graben. For the kinematic analysis, 977 fault-slip data were collected from 44 sites. The data are analyzed using a software which is based on Angelier’s reduced stress tensor algorithm. For the magnetostratigraphic analysis, 344 samples are used and the paleomagnetic measurements of those samples are performed in the Fort Hofddjik Paleomagnetism Laboratory, University of Utrecht.

The results of the kinematic analysis have shown that the Datça Basin has developed under the effects of N-S-directed tensional stress regime manifested by WNW-ESE- striking normal faults. As a result of paleomagnetic measurements, the infill sediments of the Datça Graben can be represented by a reversed-normal-reversed polarity pattern, which can be correlated to C2r.1r-C2r.1n-C2r.2r subchrons within the C2r chron of the Early Matuyama in Geomagnetic Polarity Time Scale. This means that the graben filling sediments deposited between 2.3 Ma to 1.9 Ma, in the Late Pliocene.

This age interval suggests that the Datça Graben has completed its development from half-graben to full-graben geometry by the effects of syn-sedimentary WNW-ESE-striking faults in the Late Pliocene.

This thesis is supported by TUBITAK (Grant No: 117R012).
Best practices for surface radiation observations from long-term moored buoys
Authors: Weller Robert , Farrar J. Thomas , Bigorre Sebastien , Smith Jason , Potemra James , Santiago-Mandujano Fernando
Published: March 2020

The Upper Ocean Process Group of the Woods Hole Oceanographic Institution deploys moorings with surface buoys instrumented with incoming shortwave and longwave radiometers at locations around the world.  The procedures used to calibrate the radiometers in the laboratory and to assess their performance at sea are discussed.  Some mooring deployments are done during collaborative field experiments and are months to a year in length.  Three other sites are being maintained as long-term Ocean Reference Stations (ORS), with sequential one-year deployments being used to collect ongoing time series.  The Stratus ORS, located under the marine stratus clouds off northern Chile, has been collecting surface radiation observations since 2000.  The NTAS ORS in the western tropical Atlantic has collected surface radiation data since 2001; and the WHOTS ORS north of island of Oahu, Hawaii has collected surface radiation data since 2004.  Challenges encountered in making the surface radiation observations are discussed, and the best estimates of observational uncertainties are presented.  With this understanding of the accuracies of the observations, comparisons between the buoy observations and surface radiation values from models and reanalyses are shown.  Work underway on further improvements to the approaches taken to make surface radiation observations from moored buoy are discussed, and a suggestion for field intercomparisons with other oceanic and land-based surface radiation observing platforms is put forward.
Interdecadal Connection between Arctic Temperature and Summer Precipitation over the Yangtze River Valley in the CMIP5 Historical Simulations
Authors: Li Yuefeng , Leung L. Ruby
Published: March 2020

This study assesses the ability of the Coupled Model Intercomparison Project phase 5 (CMIP5) simulations in capturing the interdecadal precipitation enhancement over the Yangtze River valley (YRV) and investigates the contributions of Arctic temperature and mid- to high-latitude warming to the interdecadal variability of the East Asian summer monsoon rainfall. Six CMIP5 historical simulations including models from the Canadian Centre for Climate Modeling and Analysis (CCCma), the Beijing Climate Center, the Max Planck Institute for Meteorology, the Meteorological Research Institute, the Met Office Hadley Centre, and NCAR are used. The NCEP–NCAR reanalysis and observed precipitation are also used for comparison.Among the sixCMIP5 simulations, only CCCma can approximately simulate the enhancement of interdecadal summer precipitation over the YRV in 1990–2005 relative to 1960–75; the various relationships between the summer precipitation and surface temperature (Ts), 850-hPa winds, and 500-hPa height field (H500); and the relationships between Ts and H500 determined using regression, correlation, and singular value decomposition (SVD) analyses. It is found that CCCma can reasonably simulate the interdecadal surface warming over the boreal mid- to high latitudes in winter, spring, and summer. The summer Baikal blocking anomaly is postulated to be the bridge that links the winter and spring surface warming over the mid- to high latitude and Arctic with the enhancement of summer precipitation over the YRV. Models that missed some or all of these relationships found in CCCma and the reanalysis failed to simulate the interdecadal enhancement of precipitation over the YRV. This points to the importance of Arctic and mid- to high-latitude processes on the interdecadal variability of the East Asian summer monsoon and the challenge for global climate models to correctly simulate the linkages.
Slab Remnant Recycling and Mantle-Wide Convection: A Separation of Time Scales
Authors: Jarvis Gary
Published: March 2020

Two dimensional numerical models of mantle convection in a cylindrical shell provide a possible geodynamic explanation for cold patches in the mantle below India and Mongolia as detected by seismic tomography. We investigate the influence of very high viscosities at mid-mantle and lower-mantle depths, as proposed by Mitrovica and Forte (2004) and Steinberger and Calderwood (2006), on mantle convective flow.  Models are considered with and without mineral phase transitions.  Our viscosity profiles are depth dependent with deep mantle viscosities increasing to values of 300 times the viscosity of the upper mantle, and then decreasing dramatically on approaching the core-mantle boundary.   The decrease of viscosity near the CMB mobilizes the overall mantle-wide flow despite very high mid-mantle viscosities.  However, cold detached slabs sinking below continental collisions become captured by the high viscosity interior and circulate slowly for times exceeding 200 Myr.  The separation of time scales for mantle-wide flow vs slab circulation, is a consequence of the high viscosity of the mid-mantle.
Natural Radionucdlides in Swiss Drinking Water; A Review and How to Comply with the New Regulations
Authors: Surbeck Heinz
Published: March 2020

Since 2017 Switzerland has new regulations concerning natural radionuclides in drinking water. They are very close to the ones in force in the EU (213/51/EURATOM). Clear limits for relevant natural radionucdlides have been replaced by rather vague “parametric values” and an “indicative dose”. 

This has lead to a general confusion at the Federal and the Cantonal environmental radioactivity labs about how to enforce the new regulations. What has to be monitored, how often and by what analytical methods ? Do we have enough data about the situation in Switzerland ? Do we need a large screening or are there criteria for a targeted search ?

To answer these questions all available data have been pooled. Data left after a critical review have been used for frequency distributions and maps.

It has turned out that natural radionuclides are not a general problem in Swiss drinking water. Hot spots are concentrated in some regions and can well be explained by the local geology.

Thus there is no need for a “blind” screening. A targeted search, based on the geology is all we need.

Concerning the analytical methods, Total-Alpha and Total-Beta measurements are out of date since many decades. They are also unreliable and give wrong results about the Ra-228 contribution to the ingested dose. Only nuclide specific analytical method are recommended.

Other recommendations are that bottled waters should be considered drinking water, complying with the same limits and that ingestion doses from radon should not be neglected.
Distribution of soil organic carbon impacted by land-use change and check dam on the Loess Plateau of China
Authors: Shi Peng , Zhang Yan , Lu Kexin , Feng Zhaohong , Yu Yang
Published: March 2020

Vegetation restoration, terrace and check dam construction are the major measures for soil and water conservation on the Loess Plateau. These effective measures of stabilizing soils have significant impacts on soil organic carbon (SOC) distribution. To understand the impact of land-use changes combined with check dam construction on SOC distribution, 1060 soil samples were collected across a watershed on the Loess Plateau. Forestland, shrubland and terrace had significant higher SOC concentrations in the 0-20 cm soil layer than that of sloping cropland.    Land use change affects the process of runoff and sediment transportation, which has an impact on the migration and transformation of soil carbon. The soil erosion of sloping farmland is the most serious, and the maximum annual erosion rate is as high as 10853.56 t·km-2. Carbon sedimented in the dam land was mainly from sloping cropland, and this source percentage was 65%. The application of hydrological controls to hillslopes and along river channels should be considered when assessing carbon sequestration within the soil erosion subsystem. 
A Spatiotemporal data Fusion method for generating a high-resolution, regular and cloud-free time series of satellite images
Authors: Shen Aojie , Bo Yanchen , Hu Duoduo
Published: March 2020

Scientific research of land surface dynamics in heterogeneous landscapes often require remote sensing data with high resolutions in both space and time. However, single sensor could not provide such data at both high resolutions. In addition, because of cloud pollution, images are often incomplete. Spatiotemporal data fusion methods is a feasible solution for the aforementioned data problem. However, for existing data fusion methods, it is difficult to address the problem constructed regular and cloud-free dense time-series images with high spatial resolution. To address these limitations of current spatiotemporal data fusion methods, in this paper, we presented a novel data fusion method for fusing multi-source satellite data to generate s a high-resolution, regular and cloud-free time series of satellite images.

We incorporates geostatistical theory into the fusion method, and takes the pixel value as a random variable which is composed of trend and a zero-mean second-order stationary residual. To fuse satellite images, we use the coarse-resolution image with high frequency observation to capture the trend in time, and use Kriging interpolation to obtain the residual in fine-resolution scale to provide the informative spatial information. In this paper, in order to avoid the smoothing effect caused by spatial interpolation, Kriging interpolation is performed only in time dimension. For certain region, the temporal correlation between pixels is fixed after the data reach stationary. So for getting the weight in temporal Kriging interpolation, we can use the residuals obtained from coarse-resolution images to construct the temporal covariance model. The predicted fine-resolution image can be obtained by returning the trend value of pixel to their own residual until the each pixel value was obtained. The advantage of the algorithm is to accurately predict fine-resolution images in heterogeneous areas by integrating all available information in the time-series images with fine spatial resolution.  

We tested our method to fuse NDVI of MODIS and Landsat at Bahia State where has heterogeneous landscape, and generated 8-day time series of NDVI for the whole year of 2016 at 30m resolution. By cross-validation, the average R2 and RMSE between NDVI from fused images and from observed images can reach 95% and 0.0411, respectively. In addition, experiments demonstrated that our method also can capture correct texture patterns. These promising results demonstrated this novel method can provide effective means to construct regular and cloud-free time series with high spatiotemporal resolution. Theoretically, the method can predict the fine-resolution data required on any given day. Such a capability is helpful for monitoring near-real-time land surface and ecological dynamics at the high-resolution scales most relevant to human activities.

 
Magnetospheric Response to Solar Wind Forcing -ULF Wave - Particle interaction Perspective
Authors: Zong Qiugang
Published: March 2020

Sudden changes in solar wind forcing, e.g., those associated with interplanetary shocks and/or solar wind dynamic pressure pulses, can cause many fundamentally important phenomena in the Earth’s magnetosphere including electromagnetic wave generation, plasma heating and energetic particle acceleration. This presentation summarizes our present understanding of the magnetospheric response to solar wind forcing in the aspects of radiation belt electrons, ring current ions and plasmaspheric plasma based on in situ spacecraft measurements, ground-based magnetometer data, MHD and kinetic simulations. 

Magnetosphere response to sudden changes in solar wind forcing, is not a “one-kick” scenario. It is found that after the impact of solar wind structures on the Earth’s magnetosphere, plasma heating and energetic particle acceleration started nearly immediately and could last for a few hours. Even a small dynamic pressure change associated with an interplanetary shock or a solar wind pressure pulse can play a non-negligible role in magnetospheric physics. The impact leads to different kinds of waves including poloidal mode ULF waves. The fast acceleration of energetic electrons in the radiation belt and energetic ions in the ring current region usually contains two steps: (1) the initial adiabatic acceleration due to the magnetospheric compression; (2) followed by the wave-particle resonant acceleration dominated by global or localized poloidal ULF waves excited at various L-shells. 

Generalized theory of drift and drift-bounce resonance with growing or decaying ULF waves  (globally distributed or localized)  has been developed to explain in situ spacecraft observations. The new wave-related observational features like distorted energy spectrum, boomerang and fishbone pitch angle distributions of radiation belt electrons, ring current ions and plasmaspheric plasma can be explained in the frame work of this generalized theory. The results showed in this presentation can be widely used in the interaction of the solar wind with other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune, and other astrophysical objects with magnetic fields.
Effects of spatial scale on fingerprinting properties and sediment contributions in the black soil region of Northeast China
Authors: Huang Donghao
Published: March 2020

Sediment provenance is an important factor in understanding soil erosion processes or assessing the ecological effects of soil and water conservation measures. Sediment fingerprinting is an effective technique used globally for identifying sediment sources. Few studies have examined sediment sources at different spatial scales. In this study, sediment fingerprinting was used with a Bayesian mixing model to quantify the relative contributions of different sediments to streambeds in the Hebei catchment (ca. 28.0 km2) and its sub-catchment (ca. 3.5 km2) in the black soil region of Northeast China. Three potential sediment sources were identified: cultivated topsoil, uncultivated topsoil, and gullies. A similar number of sediment samples were collected for each source in both catchments: 71 and 69 sediment samples from the sub-catchment and Hebei catchment, respectively. Five uniformly distributed streambed sediment samples were collected from each catchment. The results showed a significant difference in the spatial variability of fingerprinting properties between the two catchments (p < 0.01). The spatial variability in fingerprint properties of cultivated topsoil and gully soil was more sensitive to scale than that of uncultivated topsoil. The optimum composite fingerprint that was used to discriminate potential sediment sources differed between the sub-catchment and Hebei catchment. Cultivated topsoil and gully soil were the main sediment sources, comprising more than 95% of the streambed sediment. There were significant differences (p < 0.01) in the contributions of cultivated topsoil and gully soil at different spatial scales. Cultivated topsoil contributed 47.8% and 42.0% in the sub-catchment and Hebei catchment, respectively, whereas gully soil contributed 49.6% and 55.3% (mean absolute fit >0.95). The upper stream segment mainly received sediment from the gullies (>60%) and the contribution from cultivated topsoil gradually increased downstream.