bluuebunny/crossref_metadata_2025 huggingface dataset:
Forced subduction initiation at passive continental margins: Numerical modeling
Authors: Zhong Xinyi , Li Zhong-Hai
Published: March 2020

Subduction initiation (SI) induced by the tectonic boundary force may play a significant role in the Wilson cycle. In the previous analog and numerical models, the constant convergent velocity is generally applied, which may lead to large boundary forces for SI. In this study, we begin with testing the simple case of SI at passive margin with constant convergent force. The results indicate that the boundary force required to trigger the SI at passive margin with a thin and young oceanic lithosphere is much lower than that with a thick and old one. It is consistent with the multiple Cenozoic subduction zones in the Southwest Pacific, which are young ocean basin within 40 Ma and compressed by the India-Australia plate. Furthermore, we extended our model to explore a more complex case, forced SI during the collision-induced subduction transference, which is critical for Tethyan evolution. Both collision and SI processes are integrated in the numerical models. The results indicate that the forced convergence, rather than pure free subduction, is required to trigger and sustain the SI in the neighboring passive margin after collision of terrane. In addition, a weak passive margin can significantly promote the occurrence of subduction initiation, by decreasing required boundary force within reasonable range of plate tectonics. However, the lengths of subducted oceanic slab and accreting terrane play secondary roles in the occurrence of SI after collision. Under the favorable conditions of collision-induced subduction transference, the time required for subduction initiation after collision is generally within 10 Myrs, which is consistent with the general geological records of Neo-Tethys. In contrast, both Atlantic passive margin and Indian passive margin are old and stable with absence of subduction initiation in the present, which remains an open question.
Observing Evolving Subglacial Conditions with Mutitemporal Radar Sounding
Authors: Schroeder Dustin
Published: March 2020

Airborne radar sounding is the primary geophysical method for directly observing conditions beneath ice sheet and glaciers at the catchment to continent scale. From single flow-lines to regional surveys to ice-sheet wide gridded topographic datasets, radar sounding profiles provide information-rich constraints on the englacial and subglacial environment. This can include roughness, lithology, hydrology, thermal state, melt, fabric, and structure for both grounded and floating ice. However, the snap-shot view provided by one-time soundings fails to capture subsurface processes across the time-scales over which they evolve and control ice flow.  Doing so requires advancing multi-temporal radar sounding instruments, platforms, and data analysis. For example, point-measurements by ground-based or stationary sounder can be used produce local time-series observations of englacial and subglacial conditions. However, low-cost, low-power active and/or passive radar-sounder networks can dramatically extend the reach and scope of such measurements. Further, repeat surveys by sled-drawn or airborne sounders can capture seasonal and interannual subsurface variations. However, digitization of archival radar film are extending the temporal baseline for such comparison by decades, making multi-decadal studies of subsurface changes possible. Finally, the development of autonomous rover, drone, and satellite sounding platforms and systems promise to enable pervasive, stable, and frequent monitoring of subglacial conditions. Here, we discuss the advances, challenges, and the path forward to observing subsurface conditions across the full range spatial and temporal scales at which they occur.
Exploring the scattering and reabsorption of chlorophyll fluorescence: implications for remote sensing of photosynthesis
Authors: Sakowska Karolina , Cendrero-Mateo* Maria Pilar , van der Tol Christiaan , Celesti Marco , Alberti Giorgio , Juszczak Radosław , Miglietta Franco , Rascher Uwe ,   other members of the SOYFLEX campaign team
Published: March 2020

In recent years, technological progress in high-resolution field spectrometers have enabled the use of alternative tracer for constraining ecosystem-scale photosynthesis, i.e. sun-induced fluorescence (SIF). The principle underlying the use of SIF as a proxy of gross primary productivity (GPP) is based on the fact that the light energy absorbed by chlorophyll molecules can proceed into three different pathways: photochemistry, heat dissipation, and chlorophyll fluorescence. Since these processes directly compete for the same excitation energy, measurements of SIF and non-photochemical quenching (NPQ) are expected to provide information on photosynthetic performance.

However, SIF signal measured at the leaf level or beyond is affected by several processes, including wavelength dependent scattering and reabsorption, which may need to be considered when linking SIF data and photosynthetic CO2 assimilation.

To address this question, we conducted a multi-scale and multi-technique study that considered measurements of photosynthetic (GPP), optical (SIF, reflectance - R and transmittance - T), physiological (NPQ) and biophysical (the amount of absorbed photosynthetically active radiation - APAR) parameters of two soybean varieties: the MinnGold mutant, characterized by significantly reduced chlorophyll content (Chl), and the wild type, non-Chl deficient Eiko. We further used the “Soil-Canopy Observation Photosynthesis and Energy fluxes” (SCOPE) model to investigate the reabsorption and scattering of SIF. The measured leaf R, T and SIF and top-of-the-canopy R were used to retrieve biochemical and structural parameters of both varieties by inversion of the SCOPE model, while its forward mode was used to determine and correct for the scattering and reabsorption of SIF at both leaf and canopy level.

Our study revealed that despite the large difference in Chl content (the ratio of Chl between MinnGold and Eiko was nearly 1:5), similar leaf and canopy photosynthesis rates were maintained in the Chl‐deficient mutant. This phenomenon was captured neither by traditional spectral vegetation indices related to canopy greenness, nor by SIF measured in-situ. However, the modelling simulations revealed that when correcting for leaf and canopy scattering and reabsorption processes both varieties presented similar SIF yield (SIF/APAR). Furthermore, field measurements showed that APAR and NPQ in MinnGold were lower than in Eiko. This together explains the similar measured GPP and simulated SIF yield between the two varieties, and indicates that interpretation and application of SIF as a GPP tracer requires understanding and quantification of all these processes.
Long distance mobile MAX-DOAS observation of NO2 and SO2 over the North China Plain, and identification of regional transport and emission of power plant
Authors: Tan Wei , Liu Cheng , Wang Shanshan , Liu Haoran , Zhu Yizhi , Su Wenjing , Hu Qihou , Liu Jianguo
Published: March 2020

In this study, the spatial-temporal distribution of the NO2 and SO2 Vertical Columns Densities (VCDs) in the North China Plain (NCP) region was achieved by the long-distance mobile measurements using the mobile Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument. The mobile observations were taken in both summer (July 2017) and winter (January and February 2018) and the total driving mileage exceeded 3000 km. The concentrations of NO2 and SO2 pollution in different seasons and places were significantly different. During winter observations, the serious NO2 and SO2 pollution were both observed in northern Anhui province, central Shandong province, and the Beijing-Tianjin-Hebei Region. The evolution and transportation process of the three typical heavy pollution cases were discussed in detail. Combined with the WRF-chem simulated wind field information, the NO2 transportation flux from the northern Jiangsu province to the northern Anhui province was quantified to be 7.12 kg s-1. Finally, we estimated the NO2 and SO2 emissions from the Dezhou and Hengshui power plants by the plume cross section scanning observation and encircled observation methods, respectively. The NO2 and SO2 emission fluxes of the Dezhou power plant are 0.79 and 1.11 kg s-1, while the NO2 and SO2 emission fluxes of the Hengshui power plant are 0.12 and 0.36 kg s-1. This study has quantitatively analyzed the transportations of atmospheric pollutants and emissions of power plants, which is helpful to understand the occurrence and evolution of pollution and also useful for the government to put forward some policies to protect and control the atmospheric environment.
Effect of stand origin and slope position on infiltration pattern and preferential flow on a Loess hillslope
Authors: Ma Lan , Mei Xuemei , Zhu Qingke
Published: March 2020

Preferential flow is expected to provide an important pathway to replenish soil water at deep soil layers in arid or semiarid areas; however, few studies have addressed this topic, especially in semiarid Loess hillslopes. This study aimed to quantify the effect of stand origin and slope position on the contribution of preferential flow to total infiltration and spatial variations in water flow. A blue dye tracer experiment was conducted to visualize water flow in Robinia pseudoacacia plantation (PL), natural forestland (NF), and natural grassland (NG) at the upslope, midslope, and downslope, and semivariance analysis was used to determine spatial variability at the centimeter scale. The results showed that role of macropore flow was dominant in upslope and midslope, and larger in NF than that in PL and NG, due to presence of abundant root systems in the upper soil of NF. Moreover, contribution of preferential flow at the upper slope in NF was larger than that in PL. At the downslope, the role of rock fragments coverage at the downslope was emphasized, leading lateral flow dominant at the downslope in PL and NG. In addition, contribution of preferential flow and vertical variability of infiltration at the downslope in PL was higher than that in NF. The findings demonstrate that compared with PL, NF has a more positive impact on increasing infiltration and preferential flow that can replenish deep soil water, and reducing surface runoff and soil erosion. The presence of rock fragments coverage can make lateral flow dominant at the downslope on the Loess hillslope, related to water movement along the slope toward streams and catchment outlets.
Aerosol optical absorption and spectral dependence measurement with photoacoustic spectroscopy
Authors: Cao Yuan , Liu Kun , Chen Weidong , Gao Xiaoming
Published: March 2020

Light-absorbing carbonaceous aerosols mainly generated from the combustion of biomass and fossil fuels, play an important role in the global environment [1]. Multi-wavelength in-situ measurement of carbonaceous aerosol optical absorption is important both for reduce errors in assessing radiative forcing and component identification or source appointment of aerosols (such as biomass burning and diesel soot) with absorption Ångström exponent (AAE) [2]. A differential photoacoustic spectrometer (PAS) using a 438 nm laser diode was developed for simultaneously measure the aerosol optical absorption coefficient and the concentration of NO2. In order to evaluate the reliability of the differential photoacoustic spectrometer, we compared the NO2 concentration measured by PAS with the data from environmental monitoring station and showed good consistency. In the actual atmospheric measurement process, we observed a good correlation between the light absorption characteristics of aerosols and the concentration of NO2 within a certain time range. In addition, a novel multi-wavelength photoacoustic spectrometer (MW-PAS) was developed to measure the aerosol optical absorption coefficients and its wavelength-dependent characteristics in the UV-VIS-NIR bands (405, 638, 808 nm). The performance of MW-PAS was evaluated by measuring the light absorption characteristics of kerosene soot aerosol. The measurement results are agreed with the results reported in literatures [3].

 

Reference

[1] J.G. Radney, R. You, M.R. Zachariah, C.D. Zangmeister, Direct in-situ mass specific absorption spectra of biomass burning particles generated from smoldering hard and softwoods. Environ. Sci. Technol. 51, 5622-5629 (2017)

[2] T. Ajtai, N. Utry, M. Pintér, B. Major, G. Szabó, A method for segregating the optical absorption properties and the mass concentration of winter time urban aerosol. Atmos. Environ.122, 313-320 (2015)

[3] M. Gyawali, W.P. Arnott, R.A. Zaveri, C. Song, H. Moosmüller, L. Liu, M.I. Mishchenko, L.-W.A. Chen, M.C. Green, J.G. Watson, and J.C. Chow, Photoacoustic optical properties at UV, VIS, and near IR wavelengths for laboratory generated and winter time ambient urban aerosols. Atmos. Chem. Phys. 12, 2587-2601 (2012)
Assessment of IMERG precipitation over Taiwan at multiple timescales
Authors: Huang Wan-Ru , Chang Ya-Hui , Liu Pin-Yi
Published: March 2020

Since March 2014, the Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals for GPM (IMERG) has provided satellite precipitation estimates across the globe. Using gridded surface precipitation data derived from local rain gauges as a reference, this study evaluated the performance of IMERG in depicting the spatial-temporal characteristics of precipitation variations over Taiwan at multiple (including annual, seasonal, intraseasonal, diurnal and semidiurnal) timescales. The analysis focused on the period of March 2014-February 2017. Our results show that, quantitatively, IMERG underestimated the magnitude of precipitation over most of Taiwan for all the examined timescales; spatially, the bias in variability was larger over the mountainous areas than over the plain areas; temporally, the bias in variability was larger in the warm seasons than in the cold seasons. Despite the magnitude differences, IMERG was capable of qualitatively depicting several distinct features of Taiwan precipitation changes, listed as follows: (1) a bimodal pattern, with a peak in May and another peak in September, in the annual evolution of precipitation area averaged over Taiwan; (2) a seasonal counterclockwise rotation feature, with the precipitation maximum located over northern Taiwan in the winter, over northwestern Taiwan in the spring, over southwest Taiwan in the summer and over eastern Taiwan in the autumn; (3) a 10-to-35-day intraseasonal oscillation feature, with a transition of variations from smaller amplitudes in the cold seasons to larger amplitudes in the warm seasons, occurring around mid-May (i.e., the so-called Meiyu onset in Taiwan); and (4) a roughly out-of-phase feature, with a morning precipitation maximum in the winter and an afternoon precipitation maximum in the other seasons, for the diurnal evolution of the area-averaged precipitation over Taiwan. In addition, IMERG was capable of qualitatively depicting the phase evolution of semidiurnal precipitation over Taiwan in most seasons, except for the winter season.
Rapid changes of the Changjiang (Yangtze) River and East China Sea source-to-sink conveying system in response to human induced catchment changes
Authors: Gao Jianhua
Published: March 2020

    Human activity has led to rapid changes in the erosion and deposition conditions and boundaries of the different units within the Changjiang–ECS S2S conveying system, thereby resulting in major changes in the source-sink pattern of the entire S2S conveying system. After 2003, the insufficient sediment supply disequilibrated the mass balance relationship between the estuary-coast-shelf deposition systems, thereby resulting in alteration in siltation and erosion state and sea bed sediment types, and the adjustment of the geomorphology evolvement. In addition, currently, the upper reach of the Changjiang became disconnected from the Changjiang–ECS S2S conveying system to become an independent S2S conveying system. Thus, the length of the Changjiang–ECS S2S conveying system is shortened, and the source area within this S2S conveying system has significantly increased.
Formation and forward propagation of the Indosinian Nanpanjiang foreland basin and foreland thrust belt in SW China
Authors: Yang Wen-Xin , Yan Dan-Ping , Qiu Liang , Wells Michael. L , Dong Jian-Meng , Gao Tian , Zhang Zhi
Published: March 2020

Nanpanjiang Basin (also called the Youjiang Basin or Dian-Qian-Gui Basin in literatures), the foreland basin of the Indosinian orogenic belt, is located on the boundary belt between the South China and Indochina Blocks. This foreland basin is characterized by a transition from the Early Triassic shallow-marine carbonate platforms to Middle and Upper Triassic continental facies clastic rocks and reworked by the subsequent Indosinian foreland thrusting and deformations. The development of the Indosinian foreland fold-and-thrust belt remains underappreciated in part because of the loose constraints of the transition from basin deposition to deformation and erosion. In this study, we present two geological cross-sections that synthesized field geological investigations, together with the structural interpretation of three seismic profiles, and LA-ICP-MS detrital zircon age constraints. The results reveal that the thrust belt is characterized by fault-related folds with duplex and imbricate thrusts, which yield the NNE-trending regional shortening estimate of ~36%. The new constraints indicate that the Nanpanjiang foreland basin formed before 237 Ma (D11) was overridden by the following NNE-ward progressive deformations, including 237-225 Ma thick-skinned thrusts (D12), 223-183 Ma thin-skinned thrusts (D13), and after that entire basin-involved deformation (D14). Subsequently, D1 was re-deformed and superimposed by the Middle to Late Jurassic NNE-striking fault-related fold system (D2). D11-4 reveals a NNE-verging propagation in-sequence foreland thrusting which overrode the foreland basin and the corresponded NNE-ward progressive foreland basin during the Indosinian.
Entropy Ensemble Filter: Does information content assessment of bootstrapped training datasets before model training lead to better trade-off between ensemble size and predictive performance?
Authors: Foroozand Hossein , Weijs Steven V.
Published: March 2020

Machine learning is the fast-growing branch of data-driven models, and its main objective is to use computational methods to become more accurate in predicting outcomes without being explicitly programmed. In this field, a way to improve model predictions is to use a large collection of models (called ensemble) instead of a single one. Each model is then trained on slightly different samples of the original data, and their predictions are averaged. This is called bootstrap aggregating, or Bagging, and is widely applied. A recurring question in previous works was: how to choose the ensemble size of training data sets for tuning the weights in machine learning? The computational cost of ensemble-based methods scales with the size of the ensemble, but excessively reducing the ensemble size comes at the cost of reduced predictive performance. The choice of ensemble size was often determined based on the size of input data and available computational power, which can become a limiting factor for larger datasets and complex models’ training. In this research, it is our hypothesis that if an ensemble of artificial neural networks (ANN) models or any other machine learning technique uses the most informative ensemble members for training purpose rather than all bootstrapped ensemble members, it could reduce the computational time substantially without negatively affecting the performance of simulation.
The experimental research on initiation mechanism of debris flow from glacial till
Authors: Tie Yongbo , Jiang Jintao , Wang Shuai
Published: March 2020

The debris flow initiate by glacial till always dangers the local residents and facilities in alpine region in southwest China. The study of debris flow initiate from glacial till can help in understanding the mechanism of glacial till transfer to debris flow, in revealing the development of alpine mountainous topography. In this study, we designed analogue experiments that simulate the initiating process of glacial till eroded by the runoff. This research focuses on the relationship between the glacial till initiating and the critical value of flow velocity by performing analogue experiments with different flow velocity under a constant slope of landform.

A particle analysis of the modeled glacial till take from field allows understanding the structure of tested soil and standardizing the critical value of debris flow initiation. After the rush of flow with different velocity, the tested glacial till reaches a failure condition (i.e., the movement of certain particle, the undercutting of soil) which was assigned as the evidence for debris flow initiating. Results show that there are three types of erosion occurred during the experiment, the sheet erosion related to flood generation, the vertical erosion related to debris flow initiation, and lateral erosion related to the volume increasing of debris flow. Results show that the time duration of debris flow initiation are negative correlated with the velocity of flow. Because of the distribution of glacial till particle, the surface of the longitudinal profile showed corrugated form after the eroding of flow, this mainly depends on the infiltration zone where the water content of glacial till are saturated.

In the early period before the formation of debris flow, the main type of soil erosion was sheet erosion, the dual peak structure of glacial till made it easy to start up the soil with fine particles in the action of runoff scouring. Therefore, the sediment content in the flood could be improved, which provided a precondition for the formation of debris flow. In this process, the influence of runoff velocity was significant. According to the statistical results of the experiment, the faster the runoff velocity was, the faster the glacial till erosion rate was; and on the contrary, the slower the glacial till erosion rate was. We show that faster the flow velocity was, relatively shorter time the flood took to form, but relatively longer time the debris flow took to start. Finally, our results demonstrate the runoff scouring first leads to the removal of fine particles in glacial till, then the coarse grained soil was unstable due to the loss of foundation support and it initiated to form debris flows.
A Novel Framework for Landslide Risk Assessment in Mt. Umyeon, Korea
Authors: Nguyen Ba-Quang-Vinh , Lee Seung-Rae , Kim Yun-Tae
Published: March 2020

This study developed a novel landslide risk assessment framework to analyze landslide risk in Mt. Umyeon, Korea. The proposed framework included four main procedures: (1) Landslide hazard analysis using an ensemble statistical and physical model, (2) Analysis of physical vulnerability from vulnerability curve, (3) Analysis of physical vulnerability from semi-quantitative approach, (4) Risk index calculation from the results of previous steps using a proposed equation. The results of each step were compared to real landslide events occurred in July 2011 at Mt. Umyeon, Korea to confirm the reliability of the proposed risk assessment framework. The risk maps also were compared to real landslide event and showed that the proposed framework was successful in assessment of landslide risk at Mt. Umyeon, Korea. The new concept in landslide risk assessment of this study provides reliable decision-making in landslide risk assessment and management.
Geochemistry of Carbon Cycles on Rocky Exoplanets
Authors: Hakim Kaustubh
Published: March 2020

The atmospheres of rocky exoplanets are secondary and regulated by geochemical volatile cycles. Earth scientists have studied in detail the long-term inorganic carbon cycle (also known as the carbonate-silicate cycle) acting on timescales of hundreds of thousands of years. This cycle provides essential negative feedback to maintain temperate climates on Earth. With the discovery of about a thousand rocky exoplanets and ongoing hunts for an Earth-twin, it is imperative to understand the factors affecting the stability of the carbon cycle. These factors could be dependent on the orbital and stellar parameters such as stellar radiation as well as planet-specific properties such as rock composition, land and ocean fractions. On Earth, continental silicate weathering and seafloor basalt weathering act as sinks for the atmospheric carbon dioxide. In this study, we develop a novel framework to unify both weathering processes. This is done by incorporating a set of silicate weathering reactions leading to the formation of carbonates. We focus on modeling the chemistry of rock-water interaction for different rock types (depending on the planet’s surface composition), as well as pH, temperature and partial pressure of carbon dioxide. We quantify the effects of fresh rock availability for the continental weathering and landmass fractions and shallow and deep ocean fractions for the seafloor weathering. Other components of the carbon cycle such as subduction, ridge and arc volcanism are parameterized based on previous studies. The effects of planet size, redox states, and tidal locking are also investigated. Our study gives a strong control over the connection between atmospheric observables and the carbon cycle. The ultimate goal is to provide an abiotic library of geological false positives of biosignatures.
Validating future gravity missions via optical clock networks
Authors: Schröder Stefan , Springer Anne , Kusche Jürgen , Stellmer Simon
Published: March 2020

Stationary optical clocks show fractional instabilities below 10-18 when averaged over an hour, and continue to be improved in terms of precision and accuracy, uptime and transportability. The frequency of a clock is affected by the gravitational redshift, and thus depends on the local geopotential; a relative frequency change of 10-18 corresponds to a geoid height change of about 1 cm. This effect could be exploited for sensing large-scale temporal geopotential changes via a network of clocks distributed at the Earth's surface. The CLOck NETwork Services (CLONETS) project aims to create an ensemble of optical clocks connected across Europe via optical fibre links.
A station network spread over Europe, which is already installed in parts, would enable us to determine temporal variations of the Earth's gravity field at time scales of days  and thus provide a new means for validating satellite missions such as GRACE-FO or potential Next Generation Gravity Missions. However, mass changes at the surface of an elastic Earth are accompanied by load-induced height changes, and clocks are sensitive to non-loading e.g. tectonic height changes as well. As a result, local and global mass redistribution as well as local height change will be entangled in clock readings, and very precise  GNSS measurements will be required to separate them.
Here, we show through simulations how ice (glacier mass imbalance), hydrology (water storage) and atmosphere (dry and wet air mass) signals over Europe could be observed with the currently proposed/established clock network geometry and how potential extensions can benefit this observability. The importance of collocated GNSS receivers is demonstrated for the sake of signal separation.
ERT and GPR Characterization from Soil Pipe System in Brazilian Tropical Soil
Authors: Jesus Felipe , Silva Wellington , Porsani Jorge , Stangari Marcelo
Published: March 2020

A Soil Pipe System (SPS) were identified in Candói region, located in the Paraná state, southern Brazil. This region is constituted of intensive agriculture and cattle raising. SPS correspond to a structure associated to an erosive processes stage in downhill slope that tend to increase over time. The growth of the SPS results in instability to the terrain and the possibility of collapse, in this case the collapse can be accelerated by external factors, such as the overload of agricultural machinery and animals that circulate around the site, may leading to the machinery loss, animal’s death or even risk to worker safety. Frequently, the SPS are identified by surface methods that don’t provide parameters such as shape, distribution and depth. In this research, Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were used to obtain a 3D characterization of the SPS identified in a farm in Candói region to estimate the soil cover over the structure, the subsurface channels distribution and identify potential collapse risk portions. Seven ERT profiles using dipole-dipole array and twenty-one GPR profiles of 200 MHz antenna were acquired, covering an area of 900 m². The results were combined in a block diagram, which enabled: i) identify the subsurface channels distribution and direction, ii) estimate the average soil cover thickness, with 1.5 m over the whole structure. The possible connection between subsurface secondary and primary channels has also been suggested in results interpretation through of identification of a channel parallel to acquisition profiles direction. It was verified that in structure portions closer to the river next to the slope, the SPS ceiling has larger dimensions than the walls, suggesting areas with increased vertical tension, which was classified as potential collapse risk areas.
The Future of Sustainable utilization of resources on the Moon: a new international legal regime?
Authors: De Blasi Diego
Published: March 2020

Outer space activities are increasingly bringing the international (scientific) community to upper stages of knowledge and awareness. With particular reference to Lunar exploration, general involvement of all States (also within a context of public-private partnerships initiatives) towards the principle of sustainable utilization of lunar resources shall represent an important requirement for the future of all Mankind

Thus, the safeguarding of lunar environment (the equitable/intragenerational utilization of its resources) shall represent a critical issue for the whole evolutionary framework of the Corpus Iuris Spatialis

Firstly, the principle herein shall be taken into examination under the provisions laid down in the Agreement governing the Activities of States on the Moon and other Celestial Bodies. Accordingly, article 11 states “the moon and its natural resources are the common heritage of mankind”[..]; as well, “The moon is not subject to national appropriation by any claim of sovereignty, by means of use or occupation, or by any other means..” (paragraph 2)

 
Secondly, other concerns may also take into account: a) the perspective of ISRU (in situ resources utilization) processes, which shall take place towards sustainability means b) the undertaking of well balanced measures in exploring and using natural resources vis-à-vis adverse changes in lunar environment (article 7, par. 1, Moon Treaty). In addition, besides the terms pursuant to the establishment of peaceful use of (space) lunar activities, an adequate consensus shall be called upon States beyond the status quo

  
In conclusion, the aferomentioned background shall also consider the adoption of a comprehensive Additional Protocol to the Moon Treaty concerning the sustainable utilization of lunar resources. Arguably, this progressive framework may also be welcomed as milestones towards further legal developments in international space law 

 

 
Periodic modulation of the upper ionosphere by ULF waves as observed by SuperDARN radars and GPS/TEC technique
Authors: Pilipenko Vyacheslav , Kozyreva Olga , Bland Emma , Baddeley Lisa
Published: March 2020

We compare the simultaneous magnetometer, SuperDARN radar, and GPS observations during Pc5 wave event on March 02, 2002. A possible correspondence between those instruments may help to determine the mechanism of the ionosphere modulation by magnetospheric disturbances. Transient Pc5 pulsations (2.6 mHz) in the morning sector, stimulated by the solar wind density jumps, have been detected simultaneously by ground magnetometers and the Kodiak and King Salmon SuperDARN radars.  Besides that, pulsations with the same periodicity have been found in the rate of total electron content (TEC), dTEC/dt (ROT), variations in several GPS radio paths. The ratio between the spectral amplitudes of the Doppler velocities and magnetic pulsations (X component) on the ground are Vx/Bx~7-12 (m/s)/nT and Vy/Bx~27 (m/s)/nT. The ratio between the oscillation amplitudes of ROT and ionospheric Doppler meridional (Vx) and azimuthal (Vy) velocities are ROT/Vx~0.02-0.07 (dTECu/min)/(m/s) and ROT/Vy~0.004 (dTECu/min)/(m/s). The correspondence between simultaneous periodic variations of the ionospheric Doppler velocity and geomagnetic field can be reasonably well interpreted quantitively on the basis of theory of Alfven wave interaction with the thin ionospheric layer. However, order-of-magnitudes estimates of possible TEC modulation mechanisms show that a responsible mechanism which can interpret the observed ratios has not been found yet. 
Influence of thermospheric effects of solar activity on the middle atmosphere circulation and stationary planetary waves
Authors: Koval Andrey , Gavrilov Nikolai , Pogoreltsev Alexander , Shevchuk Nikita
Published: March 2020

Atmospheric large-scale disturbances, for instance planetary waves, play a significant role in atmospheric general circulation, influencing its dynamical and thermal conditions. Solar activity may influence the mean temperature at altitudes above 100 km and alter conditions of wave propagation and reflection in the thermosphere. Using numerical simulations of the general atmospheric circulation during boreal winter, statistically confident evidences are obtained for the first time, demonstrating that changes in the solar activity (SA) in the thermosphere at heights above 100 km can influence propagation and reflection conditions for stationary planetary waves (SPWs) and can modify the middle atmosphere circulation below 100 km. A numerical mechanistic model simulating  atmospheric circulation and SPWs at heights 0 – 300 km is used. To achieve sufficient statistical confidence, 80 pairs of 15-day intervals were extracted from an ensemble of 16 pairs of model runs corresponding to low and high SA. Results averaged over these intervals show that impacts of SA above 100 km change the mean zonal wind and temperature up to 10% at altitudes below 100 km. The statistically confident changes in SPW amplitudes due to SA impacts above 100 km reach up to 50% in the thermosphere and 10 – 15% in the middle atmosphere depending on zonal wavenumber. Changes in wave amplitudes correspond to variations of the EP-flux and may alter dynamical and thermal SPW impacts on the mean wind and temperature. Thus, variable conditions of SPW propagation and reflection at thermospheric altitudes may influence the middle atmosphere circulation, thermal structure and planetary waves at different altitudes.
Twenty First Century Climate Extremes Projection and Climate Vulnerability Risk Assessment in Homogeneous Climatic Zones using high Resolution Climate Data
Authors: Khan Firdos , Pilz Jürgen , Ali Shaukat , Muhammad Sher
Published: March 2020

 Climate change assessment plays a pivotal role in impact assessment studies for better planning and management in different areas. A three-steps-integrated approach is used for climate change assessment. In the first step, homogeneous climatic zones were developed by combining two statistical approaches, cluster analysis and L-moment on the basis of Reconnaissance Drought Index (RDI).  A set of GCMs was selected for each climate zone by incorporating Bayesian Model Averaging (BMA), using the outputs of fourteen GCMs for maximum, minimum temperature and precipitation. The seven best GCMs were downscaled to higher resolution using statistical methods and considered for climate extremes assessment for each zone. The performances of GCMs are different for different climate variables, however, in some cases there is coincidence. Climate extremes were analyzed for the baseline and future periods F1 (2011-2040), F2 (2041-2070) and F3 (2071-2100) for the Representative Concentration Pathways (RCPs) 4.5 and 8.5. For precipitation under the RCP4.5, most of climate extremes have decreasing/increasing trends. Further, zone-01, zone-02, and zone-03 show increasing trends while zone-04 and zone-05 have mixed (decreasing/increasing) trends in climate extremes for all periods. For temperature, sixteen climate extreme indices were considered, some important indices are: GSL, SU25, TMAXmean, TMINmean, TN10p, TN90P, TX10p, TX90P, TNN, TNX, TXN, TXX. GSL has mixed trend (increasing/decreasing) depending on cold or hot climate zones. Similarly, TN10P and TN90P also show decreasing and increasing trends, respectively, while TX10P and TX90P have decreasing and increasing trends, respectively, in RCP4.5. TNN, TNX have mixed trends and TXN, TXX have mostly increasing trends except of few time periods in which they have decreasing and insignificant trends. The overall precipitation does not show significant changes, however, the projected intensities and frequencies are changing in future and require special consideration to save infrastructure, prevent casualties and other losses. More importantly, this study will help to address different Sustainable Development Goals of the United Nation Development Program related to climate change, hunger, environment, food security, and energy sectors.
A climate classification: Mediterranean, monsoon and westerlies climates
Authors: Dai Xin-Gang , Wang Ping
Published: March 2020

This study aims to develop a large-scale climate classification for investigating the mechanisms of global climate formation in the surface. There are three types of large-scale climates, i.e., monsoon, Mediterranean and westerlies, corresponding respectively to collocation of temperature and precipitation at in-phase, anti-phase and out of phase, during seasonal cycle. The first one is called proper collocation, and the latter two are named as improper collocation, hereafter. The collocations are coupled with different seasonal moisture transport pattern with moisture divergence. Northward/southward moisture transport accompanies a moisture convergence/divergence with more/less precipitation in the season leading to different climate type. As an example, the climate around Tibetan Plateau can be attributed to four regimes, i.e., East Asia monsoon, South Asia monsoon, Central Asia and westerlies regimes, despite of the Köppen climate classification. The Central Asia regime refers to the dry climate in middle and southern part of the area, while the dry land belt with the westerlies regime extends from northern Central Asia throughout the northwestern China. The proper collocation between temperature and precipitation leads to a warm-wet climate over monsoon zones in warm season (May-October), whereas the improper one leads a hot-dry climate in Mediterranean climate areas and the dry land with the westerlies climate regime. By contrast, a mild-wet climate is in Mediterranean or quasi-Mediterranean climate areas in comparison with cold-dry climate in Asian monsoon zone during cold season (November to April). The improper collocation results in land degradation or even desertification in Mediterranean climate areas and the dry land with the westerlies regime with insufficient precipitation and over-evenly distribution of the precipitation during seasonal cycle. The improper collocation is actually made by improper dynamical and thermal dynamical collocation in regional moisture circulation associated with seasonal change of mid-latitude stationary waves in wave number and phase, which is virtually forced by large mountains and land-sea thermal contrast in the surface. Besides, analysis manifests that there exists mutually engagement between the seasonal changes in some properties of the mean moisture flows over monsoon and non-monsoon areas across Tibetan Plateau in Eurasian continent. It implies a dynamical coupling existed in large-scale moisture patterns over the earth surface.

Keywords: Large-scale climate classification, monsoon, westerlies, Mediterranean climate, Tibetan Plateau
Oldest Array (Pacific Array on the oldest seafloor), the first result
Authors: Kawakatsu Hitoshi , Utada Hisashi , Lee Sang-Mook , Kim YoungHee , Shiobara Hajime , Takeuchi Nozomu , Baba Kiyoshi , Isse Takehi , Takeo Akiko Takeo , Kim Hogyum
Published: March 2020

With a simple crustal structure and short geological history, ocean basins provide an unblemished view into mantle dynamics, including convective flow and melting processes that control deformation and evolution of Earth’s surface. With the full spectrum of plate-boundary processes and abundant mid-plate volcanism sourced deep in the mantle, the Pacific basin provides an outstanding setting to explore connections between shallow dynamics and the deep interior. Exploiting advances in seafloor instrumentation, research groups in Japan, the US, and elsewhere have demonstrated the utility of broadband ocean-bottom seismic and EM arrays for providing new, high-resolution constraints on mantle structure and dynamics. These activities have coalesced into the international collaboration Pacific Array, which seeks to merge individual efforts into a large-scale "array of arrays" that will effectively cover the entire Pacific basin diachronously over a decadal time scale.

    As a part of the Pacific Array initiative, a team comprised of scientists from Japan and South Korea has completed the Oldest Array observation on the oldest seafloor in the western Pacific. Oldest Array consists of 12-seismic and 7-EM array that was deployed in Oct-Nov, 2018, for a duration of 12 months, followed by a successfully recovered in Oct-Nov, 2019. The instruments and vessels are respectively provided by ERI and KIOST. The array covers the northwestern side of the ~170Ma old magnetic lineation triangle aiming to delineate the lithosphere-asthenosphere system beneath the oldest Pacific basin to elucidate the enigma of seafloor flattening, as well as the dynamics of the birth of Pacific plate. The initial look at data indicates beautiful recordings, and we plan to report the first analysis results at the meeting.
Cloud ice processes enhance spatial scales of organization in Arctic stratocumulus
Authors: Eirund Gesa , Lohmann Ulrike , Possner Anna
Published: March 2020

Around the globe, clouds tend to organize into cellular patterns. This phenomenon has gained growing attention in recent years, mainly due to albedo changes associated with different cloud regimes. Transitions between cloud regimes can be impacted by environmental factors such as tropospheric moisture content, large-scale subsidence, surface temperature and the ambient aerosol concentration or, more locally, precipitation formation, turbulence and boundary layer characteristics. It has been suggested that cold pool formation caused by evaporative cooling of precipitation can induce small-scale overturning circulations that promote cloud cell growth in open-cell stratocumulus clouds.

Cloud organization has so far been primarily studied for the subtropical trade wind region or deep convective clouds. In the mid and high latitudes organized cloud structures have been attributed to frontal systems in low pressure systems or cold air outbreaks. However, cloud patterns are also observed away from these large-scale phenomena in the higher latitudes. As low-level clouds in the high latitudes are mostly mixed-phase, various processes can shape cloud formation, occurrence and breakup. Processes related to the ice phase remain poorly understood and especially with regard to cloud organization remain completely unexplored.

In cloud-resolving model simulations using COSMO-LES we investigate the processes driving organization in open-cell mixed-phase stratocumuli. Similar to warm-phase clouds, MPCs develop a sub-cloud circulation caused by evaporated/sublimated precipitation, cold pool formation, and consecutive updrafts driving new convective cells. For a larger ice to liquid water ratio, we find locally stronger precipitation and larger cloud cells. Hence, a higher concentration of ice nucleating particles can induce a breakup of the stratocumulus organization, with implications for the radiative balance at the surface. A decrease in cloud condensation nuclei concentration is also found to intensify precipitation and impact cloud organization.
Pre-flight Calibration and validation test of CMM-1 Fluxgate Magnetometer MAG-O
Authors: Hu Xiaowen , Liu Kai , Li Xin , Pan Zonghao , Li Yiren , Hao Xinjun , Zhang Tielong
Published: March 2020

As one of the objectives for China’s First Mars Exploration Mission (CMM-1), the magnetic field in Mars’ near space will be measured by the Magnetometer onboard of the Orbiter (MAG-O), which consists of two fluxgate sensors and one electronic box. We conducted pre-flight calibration test to determine the temperature dependent offset and the correction matrix, which composed of sensitivities and non-orthogonality parameters. Two sets of ground validation experiments were also executed under limited condition to confirm the consistency and mutual interference of the two sensors, respectively. The results show that MAG-O meets the requirements of CMM-1 mission. This paper will introduce the procedure and results of pre-flight calibration and validation test.
The carbon-isotope signature of diagenetic carbonates
Authors: Meister Patrick , Reyes Carolina
Published: March 2020

Diagenetic carbonates often show large variations in their carbon isotope compositions. Variations are mainly the result of isotope fractionation effects during microbial metabolic processes, and these processes themselves may induce carbonate formation. Inorganic carbon from dissimilatory microbial activity shows negative carbon isotope values (d13C), in particular if methane is used as a carbon source. In turn, inorganic carbon produced during methanogenesis shows positive d13C values. The range of isotope values preserved in the carbonate phase ultimately depends on the reservoir sizes, diffusive mixing of different carbon sources, and episodic formation of carbonate (Meister et al., 2019; Meister and Reyes, 2019). The carbon-isotope signature of diagenetic carbonates therefore represents an archive of past biogeochemical activity in the subsurface.

 

References:

Meister, P. and Reyes, C. (2019) The carbon-isotope record of the sub-seafloor biosphere. In: "Tracking the Deep Biosphere through Time" (Eds. H. Drake, M. Ivarsson, C. Heim), Geosciences 9, 507, 1-25. https://doi:10.3390/geosciences9120507

Meister, P., Liu, B., Khalili, A., Böttcher, M.E., and Jørgensen, B.B. (2019) Factors controlling the carbon isotope composition of dissolved inorganic carbon and methane in marine porewater: An evaluation by reactive-transport modelling. J. Marine Systems 200, 103227, 1-18. https://doi.org/10.1016/j.jmarsys.2019.103227

 

 