bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of Wave Height with Retreating Ice Cover in the Arctic
Authors: Guan Changlong , Li Jingkai
Published: March 2020

For the Arctic surface waves, one of the most uncontroversial viewpoints is that their escalation in the past few years is mainly caused by the ice extent reduction. Ice retreat enlarges the open water area, i.e., the effective fetch, and thus allows more wind input energy and available distance for wave evolution. This knowledge has been supported by a few previous studies on the Arctic waves which analyzed the correlation between time-series variations in wave height and ice coverage. However, from the perspective of space, the detailed relationship between retreating ice cover and increasing surface waves is not well studied. Hence, we performed such a study for the whole Arctic and its subregions, which will be helpful for a better understanding of the wave climate and for forecasting waves in the Arctic Ocean.

Wave data are produced by twelve-year (2007-2018) hindcasts of summer melt seasons (May-Sept.) and numerical tests with WAVEWATCH III. When a viscoelastic wave-ice model and a spherical multiple-cell grid are applied, simulated wave heights agree with available buoy data and previous research. After the validations, simulated significant wave heights over twelve-year summer melt seasons are used to demonstrate the detailed relationship between the escalation of wave height and reduction of ice extent for the whole Arctic and seven subregions. Through least square regression, we find that the mean wave height in the Arctic Ocean will increase by 0.071m (106km2)-1 when the ice extent is smaller than 9.4×106km2, and roughly 51% is contributed by the enlarged fetch. By analyzing the nondimensional wave energy and comparing the simulated wave height with Wilson IV, we prove the swell is widespread during the summertime in the current Arctic Ocean. Furthermore, we also display the variations in probabilities of occurrence of large waves as ice-edge retreats in seven subregions. Assuming that an ice free period occurs in the Arctic in September, the model results show that the simulated mean wave height is approximately 1.6m and the large waves occur much more frequently, which mean that the growth rate of wave height will be higher if the minimum ice extent keeps reducing in the future.
Estimation of active layer thickness from modeling and InSAR deformation data at QTP
Authors: Li Rongxing , Hao Tong , Lu Ping , Qiao Gang , Chen Lemin , Han Jiangping , Zhenshi Li Zhenshi
Published: March 2020

In context of global warming, permafrost, as an important component of cryosphere in the Qinghai-Tibetan Plateau (QTP) that is located in middle and low latitudes with a high radiation intensity of high Asia mountains, is particularly sensitive to climate changes. The active layer thickness (ALT) in a permafrost area is an important index to indicate its stability. Traditional methods for measuring ALT in QTP mainly rely on ground-based field surveys and accordingly are extremely time- consuming and labor-intensive. The field works provide a good quality of data at a single site, however, such measurements are limited in spatial coverage and difficult for multi-temporal acquisitions. In addition, the harsh environment in QTP is not suitable for large-scale field measurements. In this study, the ALT of permafrost in QTP is estimated using modelling and remote sensing data. Particularly, the surface deformation on permafrost, as detected by the long-term InSAR technique, is considered as an input to the inversion model of ALT. The time-series deformation results over an experimental permafrost area were obtained by the SBAS-InSAR technique. Then, combined with the soil characteristics of soil moisture and soil thermal conductivity in the Stefan model, the melting thickness was estimated. Finally, the resulting ALT was tested and verified against a set of in-situ borehole measurements of depth-temperature.
Ambient seismic noise monitoring: an online application for decision makers – example of various applications for different slopes configurations.
Authors: Royer Alexandra , Le Breton Mathieu , Guillemot Antoine , Bontemps Noélie , Larose Eric , Baillet Laurent , Jongmans Denis , Guyoton Fabrice , Jaboyedoff Michel , Mayoraz Raphael
Published: March 2020

Monitoring landslides is essential to understand their dynamics and to reduce the risk of human losses by detecting precursors before failures. In general, surface observations need to be complemented by observation at depth, in the bulk of the material. A decade ago, the ambient seismic noise interferometry method was proposed to monitor changes in the seismic surface wave velocity. As seismic wave velocities are directly related to the rigidity of the material, any reduction of seismic velocity can be associated to a loss of rigidity with high probability (a route toward soil liquefaction or to high fracturation). This technique led to detect a velocity decrease several days before the failure of a clayey landslide [1], paving the way to a novel precursor signal that could serve for alert or early warning systems. Here we report at least five different landslides that have been monitored, over several years [2]. In this paper, we detail the standard experimental configuration, the basic signal processing procedure, the sensitivity and resolution of the method, together with its advantages and possible limitations. Environmental effects on the relative seismic velocity change are discussed.

In order to make the technology operational for decision makers, we built an online application with web portal displaying daily evolution of seismic velocity variation. This portal also integrates other available observations like environmental parameters (weather, precipitations) or surface observation (photogrammetry, gps, extensometers…).

[1] G. Mainsant, E. Larose, C. Brönnimann, D. Jongmans, C. Michoud, M. Jaboyedoff, Ambient seismic noise monitoring of a clay landslide : toward failure prediction, J. Geophys. Res. 117, F01030 (2012).

[2] M. Le Breton, N. Bontemps, A. Guillemot, L. Baillet, E. Larose, Landslide Monitoring Using Seismic Ambient Noise In-terferometry: Challenges and Applications, Earth Science Review (under review) (2020)
Estimating coastal mixing rates and submarine groundwater discharge (SGD) in Guangdong-HongKong-Macau Greater Bay Area, China using radium isotopes
Authors: Wang Xuejing , Li Hailong , Zheng Chunmiao
Published: March 2020

As a major component of the hydrological cycle, submarine groundwater discharge (SGD) has been widely recognized as a significant source of water and an important pathway for dissolved material transport from land to ocean. Natural radium isotopes are recognized as ideal tracers for effective and efficient assessment of SGD in local scales and global scales since they are conservative chemically and widely enriched in SGD. Here we report the estimates of coastal mixing rates and SGD in Guangdong-HongKong-Macau Greater Bay Area, China using radium isotopes. The distributions of short-lived 223Ra, 224Ra and long-lived 228Ra in seawater and coastal groundwater were investigated. Based on the horizontal distribution of short-lived Ra and a mixing model, the horizontal eddy diffusion coefficient in the region was estimated to be 230-1085 m2/s. The offshore fluxes of 228Ra can be derived from their across-shelf activity gradients and the eddy horizontal diffusion coefficient. Such 228Ra fluxes require a substantial volume of groundwater discharge to balance Ra removal, and thus SGD can be estimated via radium mass balance model.
How to validate calibrated/assimilated global hydrological outputs with high resolution groundwater data and regional models: an investigation of WaterGAP performance over France
Authors: Hsu Kuei-Hua , Longuevergne Laurent , Eicker Annette
Published: March 2020

The dynamic global water cycle is of ecological and societal importance as it affects the availability of freshwater resources and influences extreme events such as floods and droughts. This work is set in the frame of the GlobalCDA Research Unit. Its goal consists of developing a calibration/data assimilation approach (C/DA) to improve the tracking and predicting of freshwater availability by combining data from the global hydrological model WaterGAP with geodetic (GRACE, altimetry) and remote sensing data using an ensemble Kalman filter. The aim of this study is focused on the validation of C/DA results using independent datasets. We propose a double strategy: (1) we use regional models. We apply the high-resolution regional model AquiFR, a platform coupling the SURFEX land surface model with a set of hydrogeological models, providing storage changes in each individual compartments at daily time steps with a resolution of 8 km. (2) We built a large dataset of ~3000 monitoring boreholes in France. In order to compare the irregularly sampled borehole data with C/DA results, several interpolation methods are tested.
Atmospheric boundary layer turbulence in the presence of swell: turbulent kinetic energy budget, Monin-Obukhov similarity theory and inertial dissipation method
Authors: Zou Zhongshui
Published: March 2020

Turbulence over the mobile ocean surface has distinct properties compared to turbulence over land. This raises the issue of whether functions such as the turbulent kinetic energy (TKE) budget and Monin-Obukhov similarity theory (MOST) determined over land are directly applicable to ocean surfaces because of the existence of a wave boundary layer (the lower part of atmospheric boundary layer including effects of surface waves. We used the term “WBL” in this article for convenience), where the total stress can be separated into turbulent stress and wave coherent stress. Here the turbulent stress is defined as the stress generated by wind shear and buoyancy, and wave coherent stress accounts for the momentum transfer between ocean waves and atmosphere. In this study, applications of the turbulent kinetic energy (TKE) budget and the inertial dissipation method (IDM) in the context of the Monin-Obukhov similarity theory (MOST) within the WBL are examined. It was found that turbulent transport terms in the TKE budget should not be neglected when calculating the total stress under swell conditions. This was confirmed by observations made on a fixed platform. The results also suggested that turbulent stress, rather than total stress should be used when applying the MOST within the WBL. By combing the TKE budget and MOST, our study showed that the stress computed by the traditional IDM corresponds to turbulent stress rather than total stress. The swell wave coherent stress should be considered when applying the IDM to calculate the stress in the WBL.
Drought monitoring over Semi-Humid rain-fed winter wheat region in northwest China using remote sensing data from 1981 to 2010
Authors: Guo Ni , Wang Wei , Wang Lijuan
Published: March 2020

Drought is a widespread climate phenomenon throughout the world, as well as one of the natural disasters that seriously impact agricultural. Losses caused by drought in China reach up to about 15 percent of the all losses caused by natural disasters every year. Therefore, to monitoring the drought real-time and effectively, to improving the level of drought monitoring and early warning capacity have important significance to defense drought effectively. Satellite remote sensing technique of drought developed rapidly and had been one of the significant methods that widely used throughout the world since 1980s. Studies have shown that remote sensing drought index, especially the Vegetation drought Index (VIs) is the most suitable one that can be used in semi-arid and semi-humid climate region. We choose semi-arid region of Longdong rain-fed agriculture area in the northwest of Gansu Province as the study area, which is the most frequency area in China that drought occurs. To estimate the drought characteristics from 1981 to 2010, monthly NDVI data, the VCI and AVI index data got from NDVI data, the Comprehensive meteorological drought Index (CI) data during this period, and soil moisture observation data in 20 cm were used. Results show that:

The frequency and severity of drought in Longdong region appeared a low-high-low trend from 1981 to 2010. 1980s showed a lowest value, 1990s showed a highest value and 2000s showed a falling trend in the frequency and severity.

AVI and VCI showed a good consistency of drought monitoring together with CI and soil moisture, but a higher volatility and lagged behind for 1 month.

A Winter Wheat Drought Index (WWDI) was proposed through the analyses of inter-annual NDVI data during the winter wheat growth period and it represents the drought degree in the whole growth period commendably. Thus provide an efficient index to the winter wheat disaster assessment.

The winter wheat drought degree in the study region from 1981 to 2010 was obtained using WWDI data. The most drought years got from WWDI data were 1995, 2000, 1992, 1996 and 1997, which displayed a very high consistency with the actual disaster situations.
Investigate the Influence of Hydraulic Factors on Landslide Susceptibility of Riverbank for the Chenyulan watershed
Authors: Hong Xiao-Zhu , Chen Po-An , Chan Hsun-Chuan
Published: March 2020

The riverbank landslide is considered as the major sediment supply in the watershed. It mostly due to the river flows erode the foot of the riverbank, which makes the slope unstable. This study focused on the watershed susceptibility analysis of the riverbank landslide in the Chenyulan watershed. The Logistic regression method was used to establish the landslide susceptibility model not only with the topography, geological and anthropic factors, but also with the hydraulic factors including the hydraulic Sinuosity index, channel gradient, and concave-or-convex bank. The study areas were classified into four regions, according to the river-bed slope and confluence of rivers. The effects of the hydraulic factors on the model results were investigated. In the upstream region with mild topographic slope, the landslides were found to be dominated by the topography factors. The area under the curve (AUC) value of the model was 74.2%. In the upstream region with steep topographic slope, the steep hillslopes and the channel erosion of the concave bank produced a high weight of concave-or-convex bank in the model. The developed model exhibited an increased AUC value of 77.2%. In the downstream region, the lateral erosion of the channel increased the weights of hydraulic sinuosity index and channel gradient in the model. The developed model exhibited high area under the curve (AUC) value of 89.2%. The hydraulic factors increased the predictive performance of the model considerably.

Keyword: Riverbank, Hydraulic factors, Logistic regression
Evaluation of precipitation products based on rain gauge data and water budget in a mountainous river basin, Eastern Tibetan Plateau
Authors: Jiang Yaozhi , Yang Kun , Li Xiaodong , Zhang Wenjiang , Shen Yan , Chen Yingying , Li Xin
Published: March 2020

Precipitation in mountainous areas provides abundant water resources for downstream regions, and reliable precipitation data in these areas is of crucial importance for the management of water resources and water-related disasters. Because in-situ precipitation data are usually scarce in mountainous areas, satellite-based precipitation products are expected to play an important role; however, they should be carefully validated before application. This study evaluated the performance of three high-resolution precipitation products in the mountainous Qingyi River basin, by comparison with both rain gauge-based and water budget-based methods. The basin is located at the eastern margin of the Tibetan Plateau, and has high precipitation leading to high runoff (~1100 mm/year). The three precipitation products are CMPA (the China Merged Precipitation Analysis), IMERG (the Integrated Multi-satellitE Retrievals for GPM) and GSMaP (the Global Satellite Mapping of Precipitation). In general, both rain gauge-based and water budget-based methods showed that CMPA has the highest accuracy and IMERG has the poorest accuracy in this region. In two sub-basins with steep terrain and high precipitation, the rain gauge-based evaluation indicated negative or even positive basin-averaged biases of about 1 mm/day or less, but the water budget analysis indicated that all the products had much larger negative biases, of 2.4 ~ 3.8 mm/day. This difference likely arises because the evaluation based on rain gauge data cannot reflect errors in products at the basin-scale, due to the sparse spatial distribution of rain gauges. Finally, observed altitudinal gradients of precipitation were used to correct the precipitation products. Under this approach the water budget can be better closed but is not always satisfactory. Therefore, developing a high-quality precipitation data set for mountainous regions based only on satellite products and sparse ground observations remains challenging and other data sources (e.g. high-resolution meteorological modeling) should be taken into consideration in future.
Comparative of thermokinetic behaviors and four functional groups variations from spontaneous combustion of coal and its pre-oxidized
Authors: Deng Jun , Lv Hui-Fei , Bai Lei , Li Dajiang
Published: March 2020

In China, coal spontaneous combustion (CSC) is seriously disasters in gobs during coal seam groups mining, the secondary or multiple oxidation processes of residual coal occur inevitably, severely increasing the risk of coal fires. This paper focused on the thermal reaction behavior of two samples of raw coal and degrees of pre-oxidized (Oxi-80 °C, Oxi-130 °C, and Oxi-180 °C), we determined their characteristics of physical and chemical via thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) with the heating rates being 1.0, 2.0, 5.0, and 10.0 °C min−1. According to the characteristic temperature, the CSC process could be divided into three stages of oxidation (stage I), combustion (stage II), and thermal residual (stage III). The results indicated that for pre-oxidized coal the length of aliphatic side chains was shorter, and the number of branched aliphatic side chains was lower than that of the raw coal. The kinetic models revealed the mechanism category was changed between raw coal and pre-oxidized coal. However, the heating rate exerted little influence on the mechanism category of each stage, particularly in stage I. The average values of apparent activation energy for the pre-oxidized coal samples were lower than that of raw coal. Therefore, the pre-oxidized coal samples required less energy to activate and more readily caused spontaneous combustion than raw coal at certain stages.
Hydro-Mechanical-Chemical modelling of Brucite – Periclase (de)hydration reactions
Authors: Schmalholz Stefan Markus , Plümper Oliver , Moulas Evangelos , Podladchikov Yuri
Published: March 2020

Metamorphic reactions involving hydration and dehydration frequently occur during orogenic cycles, for example, when ambient pressure and temperature conditions change due to subduction and subsequent exhumation, or when fluids infiltrate metastable mineral assemblages at constant ambient conditions. Such (de)hydration reactions can be associated with significant volume changes, which may cause significant differential stresses in the rock, potentially leading to fracturing. The impact of (de)hydration reactions on the rock’s stress state and on the magnitudes of associated differential stresses is still controversially debated. One reason for the debate is due to the different theoretical models used to quantify and simulate (de)hydration reactions coupled with rock deformation. In many models, the rock deformation is frequently simplified, by either completely ignoring rock deformation or by considering volume deformation only. Additionally, the fluid flow is often simplified, by for example considering constant porosity. Here, we present a method to derive a system of governing equations to describe coupled Hydro-Mechanical-Chemical processes, which is suitable to quantify rock deformation coupled to (de)hydration reactions. Reactions are mainly treated as density changes whereby the density changes are determined by tabulated densities from thermodynamic Gibbs free energy minimizations in pressure, temperature and composition space. The rock deformation is quantified by the continuum mechanics force balance equations, here the Stokes equations. Considered flow laws describe either linear viscous deformation or dislocation and diffusion creep. Equations for reactions and rock deformation are coupled by several equations for the conservation of mass, such as total mass or mass of solid components stored in the solid. The governing system of equations is solved with a pseudo-transient finite difference method. For simplicity, we apply the numerical model here to several Brucite – Periclase (de)hydration reactions and show results of models with different levels of coupling, for example, constant or variable porosity. We also quantify the differential stresses associated with the (de)hydration reactions. Furthermore, we compare the modelled stresses with microstructural observations and stress estimates from high-resolution EBSD measurements in natural rock.
Estimation and Analysis of Regional Evapotranspiration in the eastern province of China with Remote Sensing data
Authors: Wu Wenyu
Published: March 2020

Evapotranspiration(ET) is a critical component of the land surface energy balance system and hydrologic processes. Analysis of spatiotemporal variations and influencing factors of ET is of great importance to evaluate the growing environment for crops and to effectively use water resources, a critical base for production in research region. The traditional methods are based on point measurement, while the remote sensing provides extensive surface information. The development of remote sensing has promoted the study of regional ET.SEBAL model is based on Surface Energy Balance Algorithm for Land and its physical meaning is clear. This model was developed to show the spatial variability of surface evapotranspiration. SEBAL model was capable of being applied to large regional areas in conjunction with Moderate-resolution Imaging Spectroradiometer (MODIS) data products.According to the shortcomings of the traditional method of calculating ET, based on SEBAL model, the daily regional evapotranspiration of Anhui Province was estimated with 1km spatial resolution by using MODIS products and a few of meteorological data(temperature, wind speed) collected in meteorological stations distributed over the study area.Because of lacking observed data from the lysimeter, the results of P-M were compared with the estimation results based on SEBAL model in this research.The comparison of the evapotranspiration estimated with MODIS products and field observation showed that the former results were lower than the latter results on the whole, and demonstrated that there existed certain trend in correlation between the two results, the average relative error was different at different land surface.The ET computation method based on Remote Sensing proves that this model has strong practicality in Anhui, and it will show great potential in this field with more optimizing the model parameters.
Evaluation of understory LAI estimation methodologies over forest ecosystem ICOS sites across Europe
Authors: George Jan-Peter , Pisek Jan ,   Tobias Biermann (2), Arnaud Carrara (3), Edoardo Cremonese (4), Matthias Cuntz (5), Silvano Fares (6), Giacomo Gerosa (7), Thomas Grünwald (8), Niklas Hase (9), Michal Heliasz (2), Andreas Ibrom (10), Alexander Knohl (11), Bart Kruijt (12), Hikdeki Kobaya
Published: March 2020

Leaf area index (i.e. one-half the total green leaf area per unit of horizontal ground surface area) is a crucial parameter in carbon balancing and modeling. Forest overstory and understory layers differ in carbon and water cycle regimes and phenology, as well as in ecosystem functions. Separate retrievals of leaf area index (LAI) for these two layers would help to improve modeling forest biogeochemical cycles, evaluating forest ecosystem functions and also remote sensing of forest canopies by inversion of canopy reflectance models. The aim of this study is to compare currently available understory LAI assessment methodologies over a diverse set of greenhouse gas measurement sites distributed along a wide latitudinal and elevational gradient across Europe. This will help to quantify  the fraction of the canopy LAI which is represented by understory, since this is still the major source of uncertainty in global LAI products derived from remote sensing data. For this, we took ground photos as well as in-situ reflectance measurements of the understory vegetation at 30 ICOS (Integration Carbon Observation System) sites distributed across 10 countries in Europe. The data were analyzed by means of three conceptually different methods for LAI estimation and comprised purely empirical (fractional cover), semi-empirical (in-situ NDVI linked to the radiative transfer model FLiES), and purely deterministic (Four-scale geometrical optical model) approaches. Finally, our results are compared with global forest understory LAI maps derived from remote sensing data at 1 km resolution (Liu et al. 2017). While we found some agreement among the three methods (e.g. Pearson-correlation between empirical and semi-empirical = 0.63), we also identified sources that are particularly prone to error inclusion such as inaccurate assessment of fractional cover from ground photos. Relationships between understory LAI and long-term climate variables were weak and suggested that understory LAI at the ICOS sites is probably more strongly determined by microclimatic conditions.

Liu Y. et al. (2017): Separating overstory and understory leaf area indices for global needleleaf and deciduous broadleaf forests by fusion of MODIS and MISR data. Biogeosciences 14: 1093-1110.
SciKit-GStat: A scipy flavored geostatistical analysis toolbox written in Python
Authors: Mälicke Mirko
Published: March 2020

Geostatistical and spatio-temporal methods and applications have made major advances during the past decades. New data sources became available and more powerful and available computer systems fostered the development of more sophisticated analysis frameworks. However, the building blocks for these developments, geostatistical packages available in a multitude of programming languages, have not experienced the same attention. Although there are some examples, like the gstat package available for the R programming language, that are used as a de-facto standard for geostatistical analysis, many languages are still missing such implementations. During the past decade, the Python programming language has gained a lot of visibility and became an integral part of many geoscientist’s tool belts. Unfortunately, Python is missing a standard library for geostatistics. This leads to a new technical implementation of geostatistical methods with almost any new publication that uses Python. Thus, reproducing results and reusing codes is often cumbersome and can be error-prone.

During the past three years I developed scikit-gstat, a scipy flavored geostatistical toolbox written in Python to tackle these challenges. Scipy flavored means, that it uses classes, interfaces and implementation rules from the very popular scipy package for scientific Python, to make scikit-gstat fit into existing analysis workflows as seamlessly as possible. Scikit-gstat is open source and hosted on Github. It is well documented and well covered by unit tests. The tutorials made available along with the code are styled as lecture notes and are open to everyone. The package is extensible, to make it as easy as possible for other researchers to build new models on top, even without experience in Python. Additionally, scikit-gstat has an interface to the scikit-learn package, which makes it usable in existing data analysis workflows that involve machine learning. During the development of scikit-gstat a few other geostatistical packages evolved, namely pykrige for Kriging and gstools mainly for geostatistical simulations and random field generations. Due to overlap and to reduce development efforts, the author has made effort to implement interfaces to these libraries. This way, scikit-gstat understands other developments not as competing solutions, but as parts of an evolving geostatistical framework in Python that should be more streamlined in the future.
Applying LSTM and GAN to build a deep learning model (TGAN-TEC) for global ionospheric TEC
Authors: chen zhou , deng Yue , wang Jing-Song
Published: March 2020

TEC is very important ionospheric parameter, which is commonly used observation for studying various ionospheric physical mechanism and other technological related to ionosphere (i.e. Global Positioning). However, the variation of global TEC is very dynamic, and its spatiotemporal variation is extremely complicated. So in this paper, we try to build a novel global ionospheric TEC (total electron content) predicting model based on two deep learning algorithms: generative adversarial network (GAN) and long short-term memory (LSTM). Training data is from 10-year IGS TEC data, which provide plenty of data for the GAN and LSTM algorithm to obtain the spatial and temporal variation of TEC respectively. The prediction accuracy of this model have been calculated under different levels of geomagnetic activity. The statistic result suggest that the proposed ionospheric model can be used as an efficient tool for ionospheric TEC short-time prediction.
Sigmoid generalized complementary equation for wet surface evaporation at the scale with changing advections
Authors: Han Songjun , Tian Fuqiang
Published: March 2020

Understandings the processes and estimating the amount of wet surface evaporation across various scales are crucial to the evaporation research. The Penman (1948) and Priestley-Taylor (1972) equations are derived for a wet patches and an extensive wet surface respectively, with an obviously different effects of advection. However, the evaporation for a wet surface between these two scales is difficult to estimate because of the changing advections. The sigmoid generalized complementary (SGC) equation, which expresses the ratio of actual evaporation (E) to Penman potential evaporation (EPen) as a function of the proportion of the radiation term (Erad) in EPen, is used to model the wet surface evaporation process by setting the symmetric parameter to be infinity, and was validated by data from flux sites over a lake site (CN-MLW) from China, a wetland site (US-WPT) from the United State, and a paddy site (JP-MSE) from Japan. The SGC equation robustly describes the growth of E/EPen upon Erad/EPen with upper flatness part over the wet surface with significant changing advection effects, and could account for the variation of the Priestley-Taylor coefficient directly. Thus, the SGC equation outperforms the Priestley-Taylor equation with a constant coefficient for estimating wet surface evaporation at the scale with changing advections.
Interaction of exogenous microbial inoculum with soil organic matter fractions
Authors: Beneduce Luciano , Plaza Cesar , Trotta Stefano , Zaccone Claudio
Published: March 2020

In a previous study (Zaccone et al., 2018. Appl. Soil Ecol. 130, 134-142), we evaluated the potential ecological partition of microbial and plant DNA across soil organic matter (SOM) fractions linked to conceptual stabilization mechanisms. We found that different microbial taxa (bacterial and fungal) seem to be specifically associated to SOM fractions. In the present work we investigated the short-term distribution of exogenous microbial population in SOM fractions following inoculation, in order to track the fate of bacterial DNA (in the form of spores) artificially spiked in bulk soils. The main hypothesis was that the colonization of external organisms proceeds from the unprotected fraction (FR) towards those protected physically and/or chemically by soil minerals from decomposition (i.e., into macro and micro-aggregates [MA, MI] or interacting with mineral surfaces [MIN]).

Three different soils with different pH, SOM content and texture were used in the experiment. One aliquot of soil was spiked with approx. 8 Log cfu of spore of Bacillus clausii from a commercial preparation of 4 strains. DNA was extracted from soil and recovered from SOM pools isolated using a physical fractionation method [Plaza et al., 2012. CLEAN-Soil Air Water 40, 134-139] and quantified by fluorescence (Qubit).

DNA recovered from spiked vs. non-spiked samples followed two different patterns of distribution, according to the SOM fractions. Total DNA in the bulk soils varied according to the soil types and the effect of spiking 8 cfu was negligible. In the SOM fractions, while MI and MIN showed different concentration according to the soil type (no apparent influence of spiking), total DNA in FR was clearly higher for spiked samples, while MA had a putative interaction between soil type and spiking. Even if very preliminary, our results point out a possible mechanism of short-term distribution of exogenous DNA (through spores and potential vegetative forms of B. clausii germinated during the incubation) from the free SOM to the macroaggregates, with no apparent influence on MI and MIN yet.

Further analyses (e.g., PCR-ARISA and qPCR) will allow to disclose whether indigenous vs. exogenous bacterial DNA are differentially distributed in SOM, possibly enhancing the description of the mechanisms underlying the distribution of microbial communities in soil, according to the different organization of the SOM in soil aggregates.
Flooding applications enabled by high resolution, high cadence imagery from the Planet constellation of satellites
Authors: Zajic Brittany , Roy Samapriya , Mascaro Joseph
Published: March 2020

Flooding is the most common and costliest global natural disaster, accounting for 43% of all recorded events in the last 20 years and increasing the global cost of flooding tenfold by 2030. Satellite imagery has proven beneficial for numerous flood use cases from historical modeling, situational awareness and extent, to risk forecasting. The addition of high resolution, high cadence satellite imagery from Planet has been widely adopted by the flood community, from researchers in academia to private companies in the insurance and financial services. 

Planet Labs, Inc. currently operates over 140 satellites, comprising of the largest constellation of Earth observation satellites. The PlanetScope dataset consists of broad coverage, always-on imaging of the entire landmass by 120+ Dove satellites at 3.7 meter resolution. Complementary to PlanetScope, the SkySat dataset includes 15 high resolution satellites imaging at .72 meter resolution with the ability to image any location on Earth twice daily via tasking commands. Next-Generation PlanetScope imagery powered by SuperDove will introduce new spectral bands and interoperability positioned for the increased utilization of Planet imagery by the flood community for both existing and new applications.
Spatial Distribution of Viscoelastic Relaxation Following a Subduction Earthquake
Authors: Ji Yuting , Sun Wenke , Tang He
Published: March 2020

Viscoelastic relaxation is generally considered as the dominant process of the long-term post-seismic deformation, while viscoelastic characteristic relaxation time represents the time scale of deformation caused by viscoelastic relaxation effect after the earthquake. The subduction earthquakes which occurred at the boundary of the ocean and continental plates often release greater stress, and the stress relaxation of mantle materials is more significant due to the response to viscoelasticity. Satellite gravity mission GRACE (gravity recovery and climate experience) is able to observe the corresponding co-seismic and post-seismic gravity changes. Therefore, in this study, we use the monthly gravity field model data of GRACE RL06 to study the post-seismic gravity changes of 2011 Tohoku earthquake and 2004 Sumatra earthquake. After removing the influence of sea level changes, GIA changes and GLDAS on the seasonal precipitation changes in the land area, as well as the sea water correction, we get the post-seismic deformation only related to the deformation of the solid earth. Then we use the attenuation function to fit each grid value and obtain the spatial distribution of viscoelastic characteristic relaxation time after rejecting the afterslip from the total post-seismic deformation. Thus，we can capture  the viscous structure in the subduction area.
The ATAL and its aerosol microphysical properties in the Asian Monsoon Anticyclone
Authors: Mahnke Christoph , Borrmann Stephan , Weigel Ralf , Cairo Francesco , Afchine Armin , Krämer Martina , Vernier Jean-Paul , Deshler Terry
Published: March 2020

During the StratoClim 2017 measurement campaign in Nepal, within the Asian Monsoon Anticyclone (AMA), measurements of the aerosols’ microphysical properties up to UT/LS altitudes were successfully completed with a modified version of the commercially available (Droplet Measurement Technologies Inc.) aerosol spectrometer UHSAS-A. Technical rearrangements of parts of the UHSAS-A were developed and implemented, which improve the instrument’s measuring performance and extend its airborne application range from around 12 km altitude to the extreme ambient conditions in the stratosphere at heights of 20 km. The measurement techniques used for this purpose were characterized by laboratory experiments.

Within the AMA region, extreme values of the particle mixing ratio (PMR) ranging between 6 mg-1 and about 10000 mg-1 were found with the UHSAS-A (particle diameter range: 65 nm to 1000 nm). The median of the PMR for all research flights was about 1300 mg-1 close to the ground. Within tropospheric altitudes, the PMR was highly variable and median values between 70 mg-1 and 400 mg-1 were observed.  At levels of 370 K potential temperature, the median PMR maximally reaches about 700 mg-1 while the 1 Hz resolved measurements show values up to about 10000 mg-1. Between 450 K and 475 K, median PMR between 40 mg-1 and 50 mg-1 were observed. The aerosol size distributions (measured by the UHSAS-A) were extended by an additional diameter size bin obtained from the 4-channel Condensation Particle counting System (COPAS), i.e. for aerosol diameter between 10 nm and 65 nm.

The UHSAS-A measured aerosol particle size distributions were compared with balloon-borne measurements (by T. Deshler et al., Dep. of Atmospheric Science, University of Wyoming, USA) at altitudes of up to 20 km. These show that the size distributions measured during the StratoClim 2017 campaign fit well within the range of the balloon-borne measurements during the Asian Monsoon season over India (Hyderabad) in 2015 and the USA (Laramie) in 2013. Further analyses of measured particle size distributions by means of backscatter ratio show remarkable consistency with CALIOP satellite observations of the ATAL during the StratoClim mission period.
MEMO2: MEthane goes MObile – MEasurements and Modelling
Authors: Walter Sylvia , Röckmann Thomas ,   MEMO2 team
Published: March 2020

Reaching the targets of the Paris Agreement requires massive reductions of greenhouse gas emissions. CH4emissions are a major contributor to Europe’s global warming impact and emissions are not well quantified yet. There are significant discrepancies between official inventories of emissions and estimates derived from direct atmospheric measurement. Effective emission reduction can only be achieved if sources are properly quantified, and mitigation efforts are verified. New advanced combinations of measurement and modelling are needed to archive such quantification.

MEMO2is a European Training Network with more than 20 collaborators from 7 countries. It is a 4-years project and will contribute to the targets of the EU with a focus on methane (CH4). The project will bridge the gap between large-scale scientific estimates from in situmonitoring programs and the ‘bottom-up’ estimates of emissions from local sources that are used in the national reporting by I) developing new and advanced mobile methane (CH4) measurements tools and networks, II) isotopic source identification, and III) modelling at different scales. Within the project qualified scientists will be educated in the use and implementation of interdisciplinary knowledge and techniques that are essential to meet and verify emission reduction goals. MEMO2facilitates intensive collaboration between the largely academic greenhouse gas monitoring community and non-academic partners who are responsible for evaluating and reporting greenhouse gas emissions to policy makers.

We will present the project, its objectives and the results so far to foster collaboration and scientific exchange.
Polymetallic nodules are essential for food-web integrity of Pacific abyssal plains
Authors: Stratmann Tanja , Amptmeijer David , Kersken Daniel , Soetaert Karline , van Oevelen Dick
Published: March 2020

The abyssal seafloor is at some locations covered with polymetallic nodules that provide hard substrate for sessile organisms. Extraction of these mineral-rich nodules will likely severely modify the trophic and non-trophic interactions within the abyssal food web, but the importance of nodules and their associated sessile fauna in supporting this food web remains unclear. Here, we present highly resolved interaction webs with ~200 (Peru Basin) and ~450 (Clarion-Clipperton Zone, CCZ) food-web compartments based on an extensive literature research. Compartments were connected with ~3,100 (Peru Basin) and ~8,500 (CCZ) trophic and non-trophic (e.g. substrate-providing nodules) links. The webs were used to assess how nodule extraction would modify the number of network compartments, number of links, link density and web connectance. We showed that nodule removal would reduce the number of food-web compartments and links by ~25% and ~35%, respectively, in the Peru Basin and by 21% and 20%, respectively, in the CCZ. Subsequent analysis identified stalked sponges, living attached to the nodules, as key structural species that support a high diversity of commensal and mutualistic fauna. We conclude that nodules are critical for food-web integrity and suggest the deployment of artificial sponge stalks as a potential mitigation strategy for deep-sea mining.
A Building Block Urban Meteorological Observation Experiment (BBMEX) over Seoul City, Korea
Authors: Park Moon-Soo , Chae Jung-Hoon , Min Jae-Sik , Kang Minsoo , Jee Joon-Bum , Kim Sang-Heon , Cho Chang-Rae
Published: March 2020

For the purpose of understanding the detailed distribution of surface and air temperatures in a high-rise building block, a 3-dimensional Building-Block Meteorological observation EXperiment (BBMEX) campaign has been carried out over typical commercial area (Gwanghwamun) in Seoul Metropolitan Area, Korea during the heat-wave and tropical night periods (5-6 August) in 2019. Several types of fixed and mobile instruments were deployed in the experiment domain: A thermal infrared imager (TIR) monitored the surface temperature with 320×240 pixels including building wall, road, sidewalks at every 10 min; 6 automatic weather stations obtained air temperature and relative humidity, and wind speed and direction at every 1 min; a mobile weather vehicle (MOVE4) monitored road surface temperatures and 4-components of radiation at 1 s on roadway; a mobile cart for meteorological observation (MCMO) monitored surface, 0.5m, 1.5m, and 2.5m air temperatures at 1 s on the sidewalk and square. The TIR exhibited that east-face of a building was strongly heated during the morning time, while horizontal surface was strongly heated near noon. Air temperatures at 2 m high in 2×2 km2 exhibited 1.5 ℃ temperature range at 06 LST, while 4.0 ℃ temperature range at 15 LST on 6 August 2019, depending on the location of site in building blocks. Air temperatures in Gwanghwamun Square were 1.5-1.7 ℃ and 0.1-2.2 ℃ higher than those observed at the Seoul synoptic station (1 km apart) in night and day, respectively. Surface and 0.5, 1,5, and 2.5m temperatures was 49.1 ℃, 38.7 ℃, 38.1 ℃, and 37.9 ℃, respectively, at 1500 LST on 6 August 2019, when the hottest air temperature in the year 2019 (36.9 ℃) was recorded at the Seoul station. Surface and air temperatures were found to be affected by many factors in a building-block such as shades, trees, building height and density, aspect ratio of building canyon, sky-view, ground-fountain, waterway, etc.
The Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex (Fennoscandian Shield): new U-Pb, Sm-Nd and Nd-Sr (ID-TIMS) isotope data on the age of formation, metamorphism and geochemical features of zircon (LA-ICP-MS)
Authors: Steshenko Ekaterina , Bayanova Tamara , Serov Pavel , Ekimova Nadezhda
Published: March 2020

The paper provides new U-Pb, Sm-Nd and Nd-Sr isotope-geochronological data on rocks of the Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex. REE contents in zircons from basic rock varieties of the Kandalaksha-Kolvitsa area have been defined in situ using LA-ICP-MS. Plots of REE distribution have been constructed, confirming the magmatic origin of zircon. Temperatures of zircon crystallization have been estimated, using a Ti-in-zircon geochronometer. For the first time, the U-Pb method with 205Pb artificial tracer has been applied to date single zircon grains (2448±5 Ma) from metagabbro of the Kolvitsa massif. The U-Pb analysis of zircon from anorthosites of the Kandalaksha massif has dated the early stage of the granulite metamorphism at 2230±10 Ma. The Sm-Nd isotope age has been estimated on metamorphic minerals (apatite, garnet, sulfides) and the rock at 1985±17 Ma (granulite metamorphism) for the Kolvitsa massif, 1887±37 Ma (high-temperature metasomatic transformations) and 1692±71 Ma (regional fluid reworking) for the Kandalaksha massif. The Sm-Nd model age of metagabbro is 3.3 Ga with negative value εNd=4.6, which corresponds either with processes of crustal contamination, or with primary enriched mantle reservoir of primary magmas.

This research was funded by the Scientific Research Contract of GI KSC RAS No. 0226-2019-0053, grants of the Russian Foundation for Basic Research NoNo. 18-05-70082 «Arctic Resources», 18-35-00246 mol_a, and the Presidium RAS Program No. 8.

 