bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term AOD trend analysis and Classification of major aerosol types over Iran from 1980 to 2018
Authors: Yousefi Robabeh , Wang Fang , Ge Quansheng , Shaheen Abdallah , Luterbacher Juerg
Published: March 2020

Based on the importance of the effects of aerosols on climate pattern change, our study contributes towards a better understanding of the Aerosol Optical Depth (AOD) trends from different datasets and the contribution of each dominant aerosol over Iran. A long-term AOD dataset (1980–2018) from the reanalysis-based Modern Era Retrospective Analysis for Research and Applications (MERRA-2) and the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) /Terra Collection 6.1(C6.1) and Level 2 (L2) in the years 2001-2018. The result of AOD trend showed some differences between MERRA-2 and MODIS in autumn and winter.  But, generally, the increasing and slightly decreasing trends appeared over the southwest and north of the country, respectively. The upward trend was mainly observed in the southwest of Iran because of the proximity to the major source areas of natural mineral dust in spring and summer of both AOD datasets which was also obtained in the regional trend analysis and the city of Ahvaz experienced a strong positive trend compared with other selected cities. Also, an unforeseen downward trend was observed in the last decade. Finally, the classification of major aerosol types during 1980-2018 indicated that the mixed aerosols (43.28%) and clean marine (37.38%) were the dominate aerosols followed by the clean continental (9.78%) and desert dust (5.56%) with minor contributions of biomass burning/urban industrial (3.98%) aerosols. Later, the increase of desert dust around 2010 was another obvious result in spring and summer. Our study results indicate that the variation in dust aerosols has a key role in determining the AOD changes in Iran which are contributed in regional climate change and environmental evolutions.
Measuring temporal and spatial scales of compound events in the United Kingdom
Authors: Tilloy Aloïs , Malamud Bruce , Winter Hugo , Joly-Laugel Amelie
Published: March 2020

Multi-hazard events have the potential to cause damages to infrastructures and people that may differ greatly from the associated risks posed by singular hazards. Interrelations between natural hazards also operate on different spatial and temporal scales than single natural hazards. Therefore, the measure of spatial and temporal scales of natural hazard interrelations still remain challenging. The objective of this study is to refine and measure temporal and spatial scales of natural hazards and their interrelations by using a spatiotemporal clustering technique. To do so, spatiotemporal information about natural hazards are extracted from the ERA5 climate reanalysis. We focus here on the interrelation between two natural hazards (extreme precipitation and extreme wind gust) during the period 1969-2019 within a region including Great Britain and North-West France. The characteristics of our input data (i.e. important size, high noise level) and the absence of assumption about the shape of our hazard clusters guided the choice of a clustering algorithm toward the DBSCAN clustering algorithm. To create hazard clusters, we retain only extreme values (above the 99% quantile) of precipitation and wind gust. We analyse the characteristics (eg., size, duration, season, intensity) of single and compound events of rain and wind impacting our study area. We then measure the impact of the spatial and temporal scales defined in this study on the nature of the interrelation between extreme rainfall and extreme wind in the UK. We therefore demonstrate how this methodology can be applied to a different set of natural hazards.
Determining water transit times in dynamic environments
Authors: Cartwright Ian
Published: March 2020

Determining the time taken for water to pass through catchments from where it is recharged to where it discharges into streams or is sampled from within the soils or aquifers (the transit time) is vital for understanding catchment functioning. Near-surface environments are dynamic and transit times are likely to vary at different stages of the hydrological cycle. Because of the lower input of bomb-pulse tritium in the southern hemisphere it is possible to determine transit times from individual tritium measurements. Additionally, because tritium is radioactive, transit times can be estimated where the catchment is not stationary. While the transit times are subject to uncertainties, this approach allows transit times at different stages of the hydrological cycles in dynamic environments to be determined.

In several southeast Australian headwater catchments, the mean transit times of stream waters at low flows range from several years to decades. The tritium activities increase at higher flows, implying that there is an input of younger water at that time. However, the tritium activities generally remain below those of recent rainfall implying that simple dilution by recent rainfall is not occurring; that conclusion is consistent with the variation in the concentrations of other geochemical tracers at different streamflows. Rather, the variations in geochemistry are consistent with shallower younger stores of water from the soils and regolith being progressively mobilised as the catchments wet up during winter. These younger water stores typically have mean transit times of at least a few years. The generally long transit times imply that the southeast Australian headwater catchments have large storage capacities, probably due to the catchments being unglaciated and deeply weathered. The observation that the transit times at high flows are still relatively long suggest that, even though they may only be active for part of the year, the shallow water stores also have relatively large volumes.

Understanding the transit times improves our ability to predict the behaviour and management of these catchments. The large storage capacities result in the catchments being resilient to year-on-year variations in rainfall and many of the headwater streams in southeast Australia have continued to flow through recent droughts. Similarly, the streams are less susceptible to inputs of surface contamination but contaminants stored in the soil water or shallow groundwater may impact the streams over prolonged periods. As the bomb-pulse tritium decays over the next few decades, determining mean transit times from single tritium measurements will become possible in northern hemisphere catchments. This will enable a better global understanding of catchment functioning in a wider range of environments.
Forecasting Hurricanes using Large-Ensemble Output
Authors: Lin Jonathan , Emanuel Kerry , Vigh Jonathan
Published: March 2020

This paper describes the development of a model framework for Forecasts of Hurricanes using Large-ensemble Outputs (FHLO). Computationally inexpensive, FHLO quantifies the forecast uncertainty of a particular tropical cyclone (TC) through O(1000) ensemble members. The model framework consists of three components: (1) a track model that generates synthetic tracks from the TC tracks of an ensemble numerical weather prediction (NWP) model, (2) an intensity model that predicts the intensity along each synthetic track, and (3) a TC wind field model that estimates the time-varying twodimensional surface wind field. In this framework, we consider the evolution of a TC’s intensity and wind field as though it were embedded in a timeevolving environmental field. The environmental fields are derived from the forecast fields of ensemble NWP models, leading to probabilistic forecasts of track, intensity, and wind speed that incorporate the flow-dependent uncertainty. Each component of the model is evaluated using four years (2015- 2018) of TC forecasts in the Atlantic and Eastern Pacific basins. We show that the synthetic track algorithm can generate tracks that are statistically similar to those of the underlying global ensemble models. We show that FHLO produces competitive intensity forecasts, especially when considering probabilistic verification statistics. We also demonstrate the reliability and accuracy of the probabilistic wind forecasts. Limitations of the model framework are also discussed.
Western Anatolian Record of Subduction Initiation through Collision
Authors: Mueller Megan , Licht Alexis , Ocakoğlu Faruk , Campbell Clay , Kaya Mustafa , Kurtoğlu Begüm , Akşit Gui , Taylor Michael , Métais Grégoire , Coster Pauline , Beard K. Christopher
Published: March 2020

The 1,700-km-long Izmir-Ankara-Erzincan suture (IAES) in Anatolia (Turkey) marks where Gondwanan and Laurasian microcontinents collided during the Cretaceous and Paleogene. The timing and dynamics of subduction and collision along the IAES are poorly constrained resulting in competitive paleogeographic scenarios requiring unique geodynamic and biogeographic reconstructions of the Mediterranean domain and broader Alpine-Zagros-Himalayan orogen. In western Anatolia, orogenic development following subduction initiation has been poorly documented. The timing of collision is debated: sometime in the Late Cretaceous to Early Eocene. Eocene slab breakoff is inferred from geochemical data but is either not supported or unresolved in mantle tomography and has not been tested using other techniques. 

We use the Saricakaya and Central Sakarya Basins in western Anatolia to appraise models of subduction initiation, intercontinental collision and slab breakoff in northwest Turkey and to discuss the implications of our results for geodynamic evolution of the IAES. From measured sections, volcanic zircon geochronology, and sedimentary provenance proxies, we demonstrate that there was little topographic development associated with early subduction stages. We refine the age of intercontinental collision to the Maastrichtian-middle Paleocene. We challenge the interpretation of Eocene slab breakoff and provide a new model of syncollisional evolution in western Anatolia in which convergence, underthrusting, and accommodation space creation dominate during the early Eocene. 

Finally, we compare results in western Anatolia to central Anatolia to determine that there was a synchronous magmatic history and onset of deformation along the IAES, thus supporting synchronous collision models of the IAES. The location, chronology and style of deformation and topographic development in western Anatolia is an important counterpoint to popular orogenic cyclicity models.
Identifying vegetation-geomorphology relationships in permafrost with airborne LiDAR, electrical resistivity tomography, seasonal thaw depth measurements, and machine learning
Authors: Douglas Thomas , Hiemstra Christopher , Anderson John , Zhang Caiyun
Published: March 2020

Mean annual temperatures in interior Alaska, currently -1°C, are projected to increase as much as 5°C by 2100. An increase in mean annual temperatures is expected to degrade permafrost and alter hydrogeology, soils, vegetation, and microbial communities. Ice and carbon rich “yedoma type” permafrost in the area is ecosystem protected against thaw by a cover of thick organic soils and mosses. As such, interactions between vegetation, permafrost ice content, the snow pack, and the soil thermal regime are critical in maintaining permafrost. We studied how and where vegetation and soil surface characteristics can be used to identify subsurface permafrost composition. Of particular interest were potential relationships between permafrost ice content, the soil thermal regime, and vegetation cover. We worked along 400-500 m transects at sites that represent the variety of ecotypes common in interior Alaska. Airborne LiDAR imagery was collected from May 9-11, 2014 with a spatial resolution of 0.25 m. During the winters from 2013-2019 snow pack depths have been made at roughly 1 m intervals along site transects using a snow depth datalogger coupled with a GPS. In late summer from 2013-2019 maximum seasonal thaw depths have been measured at 4 m intervals along each transect. Electrical resistivity tomography measurements were collected across the site transects. A variety of machine learning geospatial analysis approaches were also used to identify relationships between ecosystem characteristics, seasonal thaw, and permafrost soil and ice composition. Wintertime measurements show a clear relationship between vegetation cover and snow depth. Interception (and shallow snow) was evident in the birch and white spruce forests and where dense shrubs are present while the open tussock and intermittent shrub regions yield the greatest snow depths. Results from repeat seasonal thaw depth measurements also show a strong relationship with vegetation where mixed birch and spruce forest is associated with the deepest seasonal thaw. The tussock/shrub and spruce forest zones consistently exhibited the shallowest seasonal thaw. Roughly 60% of the seasonal thaw along the transects occurred by mid-July and downward movement of the thaw front had mostly ceased by late August with little additional thaw between August 20 and early October. Summer precipitation shows a relationship with seasonal thaw depth with the wettest summers associated with the deepest thaw. Results from this study identify clear relationships between ecotype, permafrost composition, and seasonal thaw dynamics that can help identify how and where permafrost degradation can be expected in a warmer future arctic.
Pore Structure and Petrophysical Characterization of Carbonate Rocks from Southern Lebanon
Authors: Salah Mohamed
Published: March 2020

Carbonate rocks are common in many parts of the world including the Eastern Mediterranean where they host significant groundwater supplies and are used widely in engineering as building and ornamental stones. Porosity of carbonate rocks plays a critical role in fluid storage and retrieval. The pore structure connectivity, in particular, controls many properties of rocks, and the relationships between the characteristics of individual minerals and the gross behavior of the rock. To study the relationships between porosity, rock properties, pore structure, pore size, and their impact on reservoir characteristics, several carbonate rock samples were collected from four stratigraphic sections exposed near Sidon, south Lebanon. The studied carbonate rocks are related to marine deposits of different ages (e.g., Upper Cretaceous, Eocene and Upper Miocene). In order to understand the pore connectivity, the MICP (mercury injection capillary pressure) is conducted on ten representative samples. Results from the SEM analysis indicate the dominance of very fine and fine pore sizes with various categories ranging in diameter from 0.1 to10 µm. The MICP data revealed that the pore throat radii vary widely from 0.001 to 1.4µm, and that all samples are dominated by micropore throats. The grain size analysis indicated that the studied rocks have significant amounts of silt- and clay-size grains with respect to the coarser sand-size particles; suggesting a high proportion of microporosity. Obtained results such as the poorly-sorted nature of grains, high microporosity, and the high percentage of micropore throats justify the observed low mean hydraulic radius, the high entry pressure, and the very low permeability of the studied samples. These results suggest that the carbonate rocks near Sidon (south of Lebanon) are possibly classified as non-reservoir facies.
The fate of infiltrated stormwater from infiltration basins to the stream: quantifying the impact of the urban karst
Authors: Poozan Abolfazl , Western ََAndrew , Arora Meenakshi , Burns Matthew , Fletcher Tim
Published: March 2020

Urbanization leads to severe alterations to the flow regime of receiving waters, including increased frequency and magnitude of storm flows as well as reduced baseflows. Infiltration basins are among the most widely applied stormwater control measures worldwide, in part for their ability to intercept stormwater runoff and allow it to infiltrate into the ground, with the assumption that this will recharge groundwater and thus help in restoring clean, filtered baseflows to receiving waters. Recent research has highlighted that in fact, the fate of infiltrated stormwater is highly uncertain, particularly because of likely interactions with underground infrastructure—e.g. sewer pipes, telecommunication cables, etc. These infrastructures are typically surrounded by highly permeable material which has the potential to substantially alter the way infiltrated stormwater moves through the subsurface (a phenomenon known as the urban karst).

This study aimed to predict and generalize the impact of the urban karst on infiltrated stormwater as it can provide a preferential flowpath and thus may prevent infiltrated stormwater from reaching receiving waters or may short circuit subsurface storages that can increase routing time delays and thus baseflow. In doing so, a modelling study using HYDRUS-3D was undertaken. In addition, a novel approach to generalize the results was proposed based on groundwater level and the hydraulic conductivities of soil and gravel/sand. We predicted that the impact of the urban karst on infiltrated stormwater increases whit higher groundwater levels, and greater contrasts between the hydraulic conductivity of regional soil and gravel. The HYDRUS results for a wide range of scenarios are compared with the generalization, which captures the impact of Urban Karst well.

It is important to consider the impact of the urban karst where one of the goals of building infiltration basins is to recharge the baseflow of the stream downslope. This suggests that decision on basin location is important where urban infrastructure is located between potential infiltration basin sites and downslope stream. The impact of the urban karst should be investigated at each specific site before implementing infiltration systems and this study works towards simplified representations of impact for design.
Identifying periods of forecast model confidence for improved subseasonal prediction of precipitation in southern Australia
Authors: Richardson Doug , Risbey James , Monselesan Didier
Published: March 2020

Subseasonal prediction skill of precipitation is typically low. Sometimes, however, forecasts are accurate and it would be useful to end-users to assess a priori if this might be the case. We use a 20-year hindcast data set of the ECMWF S2S prediction system and identify periods of high forecast confidence, evaluating model skill of precipitation forecasts for these periods compared to lower confidence predictions.

From reanalysis data, we derive a set of circulation patterns, called archetypes, that represent the broad-scale atmospheric circulation over Australia. These archetypes are combinations of ridges and troughs, and yield different precipitation patterns depending on the location of these features. In the literature, a typical application of circulation patterns is assigning daily reanalysis fields to the closest-matching pattern, thus obtaining conditional distributions of precipitation corresponding to key modes of atmospheric variability. A problem common to such analyses is that the precipitation distributions associated with the circulation patterns can be too similar; distinct distributions are required in order for the patterns to be useful in estimating precipitation. We show that by subsampling the archetype occurrences only when they are particularly well-matched to the underlying field, the conditional precipitation distributions become more distinct.

We subsample hindcast fields in the same way, obtaining a sample of periods when the model is confident about its prediction of the upcoming archetype. We then calculate model skill in predicting precipitation for three regions in southern Australia during such periods compared to when the model is not confident about the predicted archetype. Our results suggest that during periods of forecast confidence, precipitation skill is greater than normal for shorter leads (up to ten days) in two of the three regions (the Murray Basin and Western Tasmania). Skill for the third region (Southwest Western Australia) is greater during confident periods for lead times greater than one week, although this is marginal.
A new perspective for transpiration estimation using an extended framework of isohydricity linking to drought-driven changes in VPD and leaf area
Authors: Li Changming , Yang Hanbo
Published: March 2020

The framework of isohydry or anisohydry, which is usually defined as the sensitivity of leaf water potential (ΨL) to soil water potential (Ψs), has been rapidly adopted to solve a range of eco-hydrologic problems. While its reliability to describe the impacts of land-atmosphere interaction and seasonal phenology on plants has been recently questioned. In this study, we propose an expansion of the modern isohydricity framework to coordinate the dynamics of ΨL derived from vapor pressure deficit (VPD) and leaf area index (AL), respectively. The contributions of VPD and AL to the sensitivity of ΨL to Ψs are calculated and further evaluated using the FLUXNET dataset, as to validate the applicability of the extended concept. Then, we suggested a new method to calculate transpiration based on the new framework to establish relationship between ΨL and Ψs at ecosystem scale. Our results illustrate that the new framework is reasonable for describing the dynamics of ΨL and provides a promising potential for transpiration estimation.
A new parameterization of the accretion of cloud water by snow and its evaluation through simulations of mesoscale convective systems
Authors: Jin Han-Gyul , Baik Jong-Jin
Published: March 2020

A new parameterization of the accretion of cloud water by snow for use in bulk microphysics schemes is derived by analytically solving the stochastic collection equation (SCE), where the theoretical collision efficiency for individual snowflake–cloud droplet pairs is applied. The snowflake shape is assumed to be nonspherical with the mass- and area-size relations suggested by an observational study. The performance of the new parameterization is compared to two parameterizations based on the continuous collection equation, one with the spherical shape assumption for snowflakes (SPH-CON), and the other with the nonspherical shape assumption employed in the new parameterization (NSP-CON). In box model simulations, only the new parameterization reproduces a relatively slow decrease in the cloud droplet number concentration which is predicted by the direct SCE solver. This results from considering the preferential collection of cloud droplets depending on their sizes in the new parameterization based on the SCE. In idealized squall-line simulations using a cloud-resolving model, the new parameterization predicts heavier precipitation in the convective core region compared to SPH-CON, and a broader area of the trailing stratiform rain compared to NSP-CON due to the horizontal advection of greater amount of snow in the upper layer. In the real-case simulations of a line-shaped mesoscale convective system that passed over the central Korean Peninsula, the new parameterization predicts higher frequencies of light precipitation rates and lower frequencies of heavy precipitation rates. The relatively large amount of upper-level snow in the new parameterization contributes to a broadening of the area with significant snow water path.
Rotational Evolution of Western Anatolia since the Miocene and Its Implications on the Subduction Dynamics of Eurasia-Africa Collision
Authors: Uzel Bora , Kaymakci Nuretdin , Cakir Elif , Tosun Levent , Ozkaptan Murat , Sumer Okmen , Kuiper Klaudia , Langereis Cor , Koralay Ersin
Published: March 2020

The African-European convergent tectonic setting has resulted in a complex deformation history with several large-scale tectonic features in western Anatolia, where is dominated by a crustal-scale extension since the late Eocene. The Menderes metamorphic core complex, the İzmir-Balıkesir Transfer Zone, and the North Anatolian Fault Zone are some of these main tectonic features. To understand their spatio-temporal relationships we employ paleomagnetic, geochronologic and kinematic studies in the northernmost part of the western Anatolia, where these structures interacting with each other. 

Our results show that western Anatolia has experienced at least two separate rotational phases since the Miocene. The first rotational phase is clockwise and related volcanism is dated as 21–16 Ma. The second rotational phase is counterclockwise and related volcanic rocks are dated as 14–12 Ma. According to collected kinematic data, pervasive transcurrent tectonism was dominated during the first phase, while the second one was dominated by extensional (and/or transtensional) tectonism. Here, the mode of extension switched from distributed diffuse deformation to discrete local deformation, possibly due to tearing and retreating of the northward subducting African oceanic slab below the western  Anatolian crust. This interrelated process also led to the localization of the İzmir-Balıkesir Transfer Zone with the decoupling of strike-slip faults, and to the episodic exhumation of the Menderes metamorphic core complex. This study is supported by a Tübitak Project, Grant Number of 117R011.
Tomographic imaging of a seismic cluster in northern Taiwan and its implications for crustal fluid migration
Authors: Cheng Win-Bin
Published: March 2020

After the occurrence of the 1999 magnitude 7.3 Chi-Chi earthquake, a cluster of NE-SW trending earthquakes,
almost along the surface trace of the Lishan fault, has been detected in the northern portion of the Central Range
in northern Taiwan. From the spatiotemporal distribution of hypocenters based on cluster analysis, the Lishan
fault cluster (LFC) can quantify the evolution of seismicity as aftershocks of the 1999 Chi-Chi earthquake. The
results of seismic tomographic inversion indicate that the LFC extends down to about 10 km depth and seems
to be distributed in high Vp areas rather than in low Vp areas. This temporal expansion is attributed to fluid
diffusion. Seismic activity in the upper crust tends to be high above broad zone with low Vp in the lower crust. Our
tomographic images demonstrate a series of relatively high Vp/Vs anomalies dipping to the east which seems to
form a fluid upwelling conduit beneath the Central Range. We thus suggest that the Lishan Fault might play a role
of an active fluid conduit, fluid or fluid fluxed a partial melt of the Philippines Sea plate would be released along
the east-dipping conduit and rise gravitationally to the upper crust.
Amplitude signatures in fractured media
Authors: Stovas Alexey , Jin Song
Published: March 2020

Most of existing rocks are typically fractured that effectively result in anisotropic model of different complexity (Tsvankin and Grechka, 2011). The anisotropy signatures can be defined by traveltime and reflection&transmission amplitudes at plane interface between the rocks of different properties. Here, we focus on reflection amplitude by introducing the uniform approach to embed the fracture sets of different orientation. We utilize the linear slip theory (Schoenberg and Helbig, 1997) to add the fractures of arbitrary weakness parameters. The anisotropic model sequence consists of isotropic model (later used as a background), transversely isotropic model with a vertical symmetry axis (due to horizontal fracture set), orthorhombic model (due to horizontal and vertical fracture sets), monoclinic model with a horizontal symmetry plane (due to horizontal and two non-orthogonal vertical fracture sets) and triclinic model (due to horizontal, two non-orthogonal vertical and one inclined fracture sets). The general equation for the matrix of stiffness coefficients is given by the inverse sum of the fracture weakness matrices multiplied with density. The isotropic background stiffness coefficient matrix is defined by inverse of background weakness matrix. Each fracture weakness matrix generally has three independent parameters that are normal, tangential and horizontal weaknesses. In addition to these parameters, the fracture orientation angles in 3D space are also taken into account, and the rotation matrix is defined for each set of fractures. The uniform non-rotated weakness matrix can be chosen for brevity’s sake, however, all fracture sets might have their own weaknesses. We analyze the plane P wave reflection coefficient computed at plane interface between isotropic background and fractured background half-spaces. It is convenient to show reflection coefficient versus horizontal slowness projections. To compute reflection coefficients, we use the method developed by Jin and Stovas (2020).

The fracture sets of different orientation affect azimuthally dependent amplitude signatures. By using proposed method, the fracture set parameters and orientation can be estimated from seismic data.

References

Tsvankin, I., and V. Grechka, 2011, Seismology of azimuthally anisotropic media and seismic fracture characterization. SEG.

Schoenberg, M., and K. Helbig, 1997, Orthorhombic media: Modeling elastic wave behavior in avertically fractured earth. Geophysics, 62(2). 1954-1974.

Jin, S., and A. Stovas, 2020, Reflection and transmission approximations for monoclinic media with a horizontal symmetry plane. Geophysics (early view).
GPS Constraints on the Active Deformation in Tunisia: Implications on the Geodynamics of the Western Mediterranean
Authors: Masson Frédéric , Meghraoui Mustapha , Bahrouni Najib , Saleh Mohammed , Ridha Maamri , Faouzi Dhaha , Ulrich Patrice , Bernard Jean-Daniel
Published: March 2020

The plate boundary in the western Mediterranean includes the Tunisian Atlas Mountains. We study the active deformation of this area using GPS data collected from 2014 to 2018. WNW to NNW trending velocities express the crustal motion and geodetic strain field from the Sahara platform to the Tell Atlas, consistent with the African plate convergence. To the south, the velocities indicate a nearly WNW-ESE trending right-lateral motion of the Sahara fault-related fold belt with respect to the Sahara Platform. Further north and northeast, the significant decrease in velocities between the Eastern Platform and Central – Tell Atlas marks the NNW trending shortening deformation associated with local ENE – WSW extension visible in the Quaternary grabens. The velocity field and strain distribution associated with the active E-W trending right-lateral faulting and NE-SW fault-related folds sustain the existence of three main tectonic blocks and related transpression tectonics. The velocity field and pattern of active deformation in Tunisia document the oblique plate convergence of Africa towards Eurasia. 
Urban Soils Mycobiota of the Subarctic (Apatity, Murmansk region, Russia)
Authors: Korneykova Maria , Nikitin Dmitriy , Dolgikh Andrey , Soshina Anastasia
Published: March 2020

The soils mycobiota of Apatity was first characterized. Significant differences in quantitative and qualitative parameters of urban soils fungal complexes of the Subarctic zone in comparison with zonal soils were revealed. It was shown that the biomass of fungi in the soil of the residential area of Umbric Leptic Entic Podzol (Arenic, Neocambic) is 0.18 – 0.20 mg/g, in the background forest soil Folic Leptic Albic Podzol (Arenic) – 0.31 mg/g. The smallest values (0.04 – 0.08 mg / g) are typical for areas with no vegetation and a densely compacted surface (playground - Leptic Entic Podzol (Arenic, Neocambic, Technic), unpaved pedestrian walkway – Umbric Leptic Entic Podzol (Arenic, Neocambic).

In the soils of recreational and forest areas, fungi were mainly in the form of mycelium (66-70% of the total biomass), while in the soils of residential and agricultural areas in the form of spores. Spores are mainly represented by small forms up to 3 microns. The amount of large spores is insignificant, but they were mainly detected in the soil of the residential area.

The number of copies of ITS rRNA genes of fungi in soils of different functional zones varies from 4.0×109 to 1.14×1010 copies/g of soil, with the highest values in the natural Podzol of the forest zone and Podzol of the unpaved pedestrian walkway.

The number of micromycetes CFU in the upper soil horizon ranges from 1×103 to 9×104 CFU/g of soil, reaching maximum values in the soil of the Umbric Leptic Entic Podzol recreation zone (Arenic, Neocambic, Technic). The features of cultivated forms of micromycetes distribution on the soil profile in different functional zones were revealed: in the Podzol of the residential area, the maximum accumulation of fungi was noted in the lower horizons, while in the soil of the recreational, agricultural and forest areas, their maximum number was noted in the top horizon. However, the first two differed from the background one in the absence of a second maximum accumulation of micromycetes in the illuvial Bs horizon.

In general, urban soils were characterized by a low species diversity of micromycetes complexes and a specific structure significantly different from the background soils. The genus Penicillium is characterized by maximum species diversity. Trichocladium griseum and Penicillium dierckxii dominate in the communities of microscopic fungi in the soil of the residential zone, P. melinii in the soil of the recreational areas and in the playground, in the soil of agricultural area Plaggic Entic Podzol (Arenic) - micromycetes of the genus Fusarium, and in the background forest soil - P. decumbens.
New insight into spheroidal iron (oxyhydr)oxide concretion formation models: Diagenetic concretion nucleation associated with neutral fluids from a mafic intrusion
Authors: Potter-McIntyre Sally , Filiberto Justin , Schwenzer Susanne , Crandall Jake , Perl Scott , Baharier Bea
Published: March 2020

Directly west of the San Rafael Swell on the Colorado Plateau in the western U.S., the Jurassic Entrada Sandstone is intruded by a ~2 km long mafic dike. The dike is Miocene; however, the area is also crosscut by Laramide (~50Ma) clusters of deformation bands that are up 500 m long and up to ~3 m wide. The mafic intrusions infused the area with fluids that bleached the red sandstone directly surrounding the dike. On one side of the dike, the bleached area terminates at an adjacent deformation band set ~475 m south of the dike. Field observations suggest that the dike acted as a baffle preventing fluids from migrating further into the sandstone. Spheroidal calcite and iron (oxyhydr)oxide concretions are present in the bleached host rock, although calcite concretions (1-3 cm diameter) are present throughout the area on both sides of the deformation bands and in both red and white host rock. Iron (oxyhydr)oxide concretions (1-5 cm diameter) are limited to the uppermost bleached section between the dike and the deformation band set. Some iron concretions have solid interiors, and some have well-cemented rinds with interiors depleted of cement. Additionally, some iron concretions are nucleated on individual deformation bands that are ~2 mm wide and iron (oxyhydr)oxide cemented joint faces are also present. Thermochemical modeling shows the infiltrating Miocene fluids were CO2-bearing, but near neutral pH. The restricted location of the iron (oxyhydr)oxide concretions and relation to the calcite concretions suggest that stagnation of fluid is needed for spheroidal iron oxyhydroxide concretion formation. Calcite concretion nucleation and growth may be quicker resulting in more widespread occurrences, and/or may have preceded the Miocene fluids that infiltrated the unit. The evidence presented here shows that recently proposed models calling for calcite concretion precursors and acidic fluids for iron (oxyhydr)oxide concretion formation may not be correct.
Inherent Uncertainty Disguises Attribution of Reduced Atmospheric CO2 Growth to Mitigation for up to a Decade
Authors: Spring Aaron , Ilyina Tatiana , Marotzke Jochem
Published: March 2020

On inter-annual time scales the growth rate of atmospheric CO2 is largely driven by the response of the land and ocean carbon sinks to climate variability. Therefore, climate mitigation in terms of emission reductions can be disguised by internal variability.
However, the probability that emission reductions induced by a policy change caused reductions in atmospheric CO2 growth trend is unclear.
We use 100 historical MPI-ESM simulations and interpret mitigation in 2020 as a policy shift from Representative Concentration Pathway 4.5 to 2.5 in a comprehensive causation attribution framework.
Here we show that five-year CO2 trends are higher in 2021-2025 than over 2016-2020 in 30% of all realizations in the mitigation scenario, compared to 52% in the non-mitigation scenario. Therefore, mitigation is sufficient or necessary to cause these trends by 42% or 31%, respectively and therefore far from certain.
A stronger increase in atmospheric CO2 trends despite emission reductions is possible when the global carbon cycle triggered by internal climate variability releases more CO2 than mitigation saves. Such trends might occur for of up to ten years. Certainty that mitigation causes trend reductions is only reached after ten or fifteen years, respectively of the type of causation.
Our analysis showcases the inherent uncertainty of near-term CO2 projections. Assessments of the efficacy of mitigation in the near term are incomplete without quantitatively considering internal variability.
Large amplitude exospheric waves seen in MAVEN NGIMS data
Authors: Williamson Hayley , Johnson Robert , Leclercq Ludivine , Elrod Meredith
Published: March 2020

We examine high altitude gravity waves in the upper atmosphere of Mars using the data from the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, orbiting Mars since late 2014. Since the Martian atmosphere is very thin it is also highly perturbed and the effects of these perturbations are debated. Therefore, on 252 trajectories through the Martian atmosphere large amplitude, high altitude perturbations seen in the NGIMS database are examined. When the perturbations are organized by column density rather than altitude, the perturbations both peak and dissipate at similar column densities. These perturbations also increase the O/CO2 ratio above that measured for orbits without a significant perturbation. To understand this effect, the perturbations are subsequently categorized by location and found to be roughly consistent with wave activity seen lower in the atmosphere. Because the NGIMS data for each perturbation cannot measure the temperature or long term behavior, we simulate wave propagation using a Direct Simulation Monte Carlo (DSMC) model. The results from such simulations suggest that these perturbations are most likely large amplitude acoustic gravity waves, whose high frequency and fast phase speed allow them to propagate into the Martian exosphere, affecting the diffusive separation of species and depositing heat.
On the magnetic characteristics of magnetic holes in the solar wind between Mercury and Earth
Authors: Volwerk Martin , Goetz Charlotte , Plaschke Ferdinand , Karlsson Tomas , Heyner Daniel
Published: March 2020

The occurrence rate of linear and pseudo magnetic holes has been determined during MESSENGER’s cruise phase starting from Earth (2005) and arriving at Mercury (2011). It is shown that the occurrence rate of linear magnetic holes, defined as a maximum of 10â—¦ rotation of the magnetic field over the hole, slowly decreases from Mercury to Earth. The pseudo magnetic holes, defined as a rotation between 10â—¦ and 45â—¦ over the hole, have mostly a constant occurrence rate, with a slight increas in front of the Earth and a decrease around the Earth. The width and depth of these structures seem to strongly differ depending on whether they are inside
or outside of Venus’s orbit.
BLISS: a backscattering space-borne LIDAR simulator
Authors: Schmisser Roseline , Chinaud Jordi , Galaup Philippe
Published: March 2020

Long-term data on clouds and aerosols are of critical importance to accurately model climate change. In particular, CALIPSO-like LIDAR missions give access to data on clouds height, distribution, optical depths… as well as information on aerosol types and concentration.

In this context, BLISS (Backscattering Lidar Signal Simulator) has been developed by CNES and Thales Services to simulate the return signal received by a backscattering space-borne LIDAR and the associated data processing (level 0 to level 2), in order to perform mission dimensioning studies as well as sensitivity studies on instrument or geophysical parameters. Given a specific input scene, it provides the vertical profiles of clouds and aerosol actually in the atmosphere as seen by the LIDAR and can also provide a profile of the first few meters inside the oceans – if any – thus representing the backscattering of light by particles as plankton.  It has already especially been used on MESCAL phase 0 and its outputs have been compared with other existing LIDAR codes (like the one developed by NASA LARC).

BLISS user interface, its different modules and an associated end-to-end simulation will be presented.
The global dominance of the Atlantic circulation, seen through boundary pressures.
Authors: Hughes Chris W. , Williams Joanne , Blaker Adam , Coward Andrew C.
Published: March 2020

The rapid propagation of boundary waves (or, equivalently, the strong influence of topography on vorticity balance) ensures that bottom pressure along the global continental slope reflects large scale ocean processes, making it possible to see through the fog of the mesoscale, which obscures many observable quantities. This fact is exploited in systems to monitor the Atlantic Meridional Overturning Circulation (AMOC). Here, we use diagnostics from an ocean model with realistic mesoscale variability to demonstrate two things. First: boundary pressures form an efficient method of monitoring AMOC variability. Second: pressures are remarkably constant along isobaths around the global continental slope, varying by less than 5 cm sea-level-equivalent over vast distances below the directly wind-driven circulation. In the latter context, the AMOC stands out as a clear exception, leading to a link between the AMOC and differences in the hydrography of entire ocean basins.
Seasonal responses of maize growth and water use to elevated CO2 based on WTDPED experiments: evidences from multiple ecophysiological indicators
Authors: Ma Ying
Published: March 2020

The increase in atmosphere carbon dioxide (CO2) concentrations has been the most important environmental change experienced by agricultural systems. It is still uncertain whether grain yield of the global food crop of maize will remain unchanged under a future elevated CO2 (eCO2) environment. A water transformation dynamic processes experimental device (WTDPED) was developed using a chamber coupled with two weighing lysimeters and a groundwater supply system to explore the water-related yield responses of maize to eCO2. Two experiments were conducted via the WTDPED under eCO2 (700 ppm) and current CO2 (400 ppm) concentrations. Seasonal changes in multiple ecophysiological indicators and related hydrological processes were compared between these two experiments. The results showed that the leaf nitrogen (N) content, chlorophyll content, net photosynthesis rate, and transpiration rate (Tr) consistently decreased during the seedling to filling stages but notably increased at the maturity stage due to eCO2 (P<0.05). Nevertheless, the effects were not significant over the entire growing season or for other indicators, i.e., the leaf carbon (C) content, C/N ratio, and leaf area index (P>0.05). Significant decreases in crop height (mean of 15.9%, P<0.05) associated with notable increases in stem diameter (mean of 14.9%, P<0.05) were found throughout the growing season. Dry matter per corncob at the final harvest decreased slightly under eCO2 (mean of 7.7 g, P >0.05). Soil moisture was not conserved by the decline of Tr ahead of the filling stage when soil evaporation was likely promoted by eCO2 instead. The total evapotranspiration changed little (0.2%) over the entire growing season. Although the leaf water use efficiency increased significantly at every growth stage (mean of 27.3%, P<0.05), the grain yield, water productivity and irrigation water use efficiency were not improved noticeably by eCO2. This study is critical to accurately predict future crop yield and hydrological changes under climate change.
Slow-release of fertilizer in soil using pectin/calcium-bentonite hydrogel
Authors: Pajarito Bryan , Kho John Anthony , Mayo Raymond , Ong Jendrich Spencer , Jovellana John Andrew Kane
Published: March 2020

Plant survival and growth are greatly affected by moisture and nutrient loss around root zones. Water and nutrient retaining agents such as hydrogels have been gaining popularity to solve this problem, but most commercial hydrogels are composed of non-biodegradable and synthetic components.  In this study, we successfully prepared hydrogels made of biodegradable pectin and naturally-occurring calcium bentonite. The synthesized hydrogels contained varied loadings of fertilizer (equivalent to 0, 0.2, 0.6, and 0.85 g NPK L-1 soil). We characterized the hydrogels in terms of morphology (scanning electron microscopy/SEM), nutrient P and K concentration (X-ray fluorescence/XRF analysis), and degree of swelling in water (gravimetric method). We also determined the nutrient retention capacity and release of the hydrogels using a soil column leaching setup coupled with periodic monitoring of conductivity and total dissolved solids of column leachate. 

SEM indicates the porous structure of the hydrogels, while XRF confirms the successful loading of fertilizer in the hydrogels. The hydrogel at 0.2 g NPK L-1 soil has the highest degree of swelling in the water at 692.5%. The nutrient retentions of soil columns containing fertilizer-loaded hydrogels (0.2, 0.6, and 0.85 g NPK L-1 soil) are greater by 35.5, 11.5, and 20.1%, respectively, compared to the control (soil column without hydrogel). Our measurements of fertilizer release rate also indicate that the presence of hydrogel in the soil column slows down the release of fertilizer as detected in the column leachates. We conclude that the pectin/calcium-bentonite hydrogels are effective in retaining water and reducing the release of fertilizer from the soil. With the biodegradability of pectin and natural occurrence of calcium bentonite, the hydrogel has the potential for sustainable management of slow-release fertilizer systems. 
Variability of planetary high-altitude frontal zone and jet stream in the Northern hemisphere from 1991 to 2019 in the summer period
Authors: Durneva Evgeniya
Published: March 2020

Global climate changes particularly observed in the Arctic region are influenced on the formation of circulation in the atmosphere. The planetary high-altitude frontal zone for midlatitudes has analyzed from 1991 to 2019 in the summer period, on July. Deviations poleward from the normal of high-altitude frontal zone and jet stream have observed, particularly marked over the Eurasia during last decades. Changes in the form and decreasing of intensity of high-altitude jet streams are noted, which further contribute to the formation of blocking anticyclones and increasing in the incidence of anomalous weather events.

The case of July 2018 is presented in this work. The anomalous high temperature in Scandinavia and north area of the European part of Russia have observed due to formation of the blocking over this territory. The main reason for the formation of blocking is the instability of the jet stream. The characteristics (intensity, position relative to the North Pole and form) of the arctic and midlatitudes jet stream have analyzed.