bluuebunny/crossref_metadata_2025 huggingface dataset:
Solar Wind induced waves in the skies of Mars: Ionospheric compression, energization, and escape resulting from the impact of ultra-low frequency magnetosonic waves generated upstream of the Martian bow shock
Authors: Collinson Glyn , Wilson III Lynn , Omidi Nick , Sibeck David , Espley Jared , Fowler Christopher , Mitchell David , Grebowsky Joseph , Mazelle Christian , Ruhunusiri Suranga , Halekas Jasper , Jakosky Bruce , Harada Yuki
Published: March 2020

Using data from the NASA Mars Atmosphere and Voltatile EvolutioN (MAVEN) and ESA Mars Express spacecraft, we show that transient phenomena in the foreshock and solar wind can directly inject energy into the ionosphere of Mars. We demonstrate that the impact of compressive Ultra-Low Frequency (ULF) waves in the solar wind on the induced magnetospheres drive compressional, linearly polarized, magnetosonic ULF waves in the ionosphere, and a localized electromagnetic "ringing" at the local proton gyrofrequency. The pulsations heat and energize ionospheric plasmas. A preliminary survey of events shows that no special upstream conditions are required in the interplanetary magnetic field or solar wind. Elevated ion densities and temperatures in the solar wind near to Mars are consistent with the presence of an additional population of Martian ions, leading to ion-ion instablities, associated wave-particle interactions, and heating of the solar wind. The phenomenon was found to be seasonal, occurring when Mars is near perihelion. Finally, we present simultaneous multipoint observations of the phenomenon, with the Mars Express observing the waves upstream, and MAVEN observing the response in the ionosphere. When these new observations are combined with decades of previous studies, they collectively provide strong evidence for a previously undemonstrated atmospheric loss process at unmagnetized planets: ionospheric escape driven by the direct impact of transient phenomena from the foreshock and solar wind.
Mechanisms controlling explosive-effusive transition of Teide-Pico Viejo complex dome eruptions.
Authors: Dorado Olaya , Andújar Joan , Martí Joan , Geyer Adelina
Published: March 2020

The Teide-Pico Viejo (PT-PV) stratovolcanoes constitute one of the major potentially active volcanic complexes in Europe. PT-PV was traditionally considered as non-explosive system however, recent studies (ie. García et al. 2014) have pointed out that the explosive character of phonolitic magmas, including plinian and subplinian eruptions and generation of pyroclastic density currents, have also been significant within the last 30 kyr volcanological record. This explosive activity is mostly associated to satellite dome vents, like the one studied in this work, Pico Cabras. Dome-forming eruptions usually present sudden transitions between explosive and effusive activity. A better knowledge of this type of eruptions and about the main mechanisms controlling the changes in eruptive dynamics is required to undertake a comprehensive volcanic hazard assessment of Tenerife Island. In this study, we conduct a petrological and mineral characterization of the different eruption phases of Pico Cabras (pumice and lava flow samples for the explosive and effusive activity, respectively) with the aim of determining the factors that control these changes in the volcanic activity. Products were characterized with Scanning Electrom Microscope, and mineral phases, glass and volatile species (F, Cl) were analysed with electron microprobe and micro-XRF. The pre-eruptive conditions of the magma (pressure, temperature and water dissolved in the magma) were determined first by using available geothermobarometers, geohygrometers (Masotta et al., 2013; Mollo et al., 2015) and compared to those retrieved by using available phase equilibria experiments from the literature (ie. Andújar and Scaillet, 2012).

Our results suggest the presence of a compositionally stratified magma chamber at 1 kbar±0.5kbar prior to Pico Cabras eruption in which the differences in the eruptive styles are controlled by the temperature and the amount of volatiles dissolved in the melt. The explosive phase is related to the upper part of the magma chamber at 725ºC±25ºC and 3,5-5 wt% H2O and the effusive phase with the main body of the chamber at 880ºC±30ºC and 2,5-3 wt% H2O. Feldspar zonations show that overturn events occurred in the different layers of the magma chambers (“self-mixing”) and suggest that the eruption was triggered by underplating of mafic magma without magma mixing. Chemical composition of some feldspars from the explosive phase are equivalent to those found in El Abrigo eruption, the last caldera-forming episode (ca. 190 ka), demonstrating that PT-PV volcanic system is still capable of producing evolved and very explosive magmas.

This research has been partially funded by a CSIC JaeIntro grant and the EC Grant EVE (DG ECHO Ref: 826292).
Research on the Convergence Condition of Iterative Solution for the Mathematical Model of Reservoir Power Generation Optimization
Authors: Tan Anqi , Chen Senlin
Published: March 2020

Discrete differential dynamic programming algorithm is widely used in reservoir power generation dispatching, but the problem of "dimensional disaster" still exists, and there are different degrees of limitations such as premature convergence and uncertainty of convergence. In the existing monographs and literature, there is little research on the algorithm itself. The iterative solution convergence conditions, initial parameters, and initial trajectory selection of the mathematical model for reservoir power generation scheduling optimization have important effects on the iterative process and results. The convergence conditions directly determine when the iterative process converges and its calculation results. In this paper, the solution convergence conditions are studied. Based on the calculation results of the mathematical model of reservoir power generation scheduling optimization, the method of iteratively solving the convergence conditions when different state quantities are used as control factors is systematically studied. Shuibuya Hydropower Station Scheduling results show that using this method to determine the termination step size can shorten the calculation time and obtain an optimization result close to the ideal value, avoid the randomness of the convergence process of the iterative solution, and improve the accuracy of the DDDP algorithm and the efficiency of the target value.
Roles of magnetospheric convection on nonlinear drift resonance between electrons and ULF waves
Authors: Zhou Xuzhi , Li Li , Omura Yoshiharu , Zong Qiugang , Fu Suiyan , Rankin Robert , Degeling Alex
Published: March 2020

In the Earth's inner magnetosphere, charged particles can be accelerated and transported by ultralow frequency (ULF) waves via drift resonance. We investigate the effects of magnetospheric convection on the nonlinear drift resonance process, which provides an inhomogeneity factor S to externally drive the pendulum equation that describes the particle motion in the ULF wave  field. The S factor, defined as the ratio of the driving amplitude to the square of the pendulum trapping frequency, is found to vary with magnetic local time and as a consequence, oscillates quasi-periodically at the particle drift frequency. To better understand the particle behavior governed by the driven pendulum equation, we carry out simulations to obtain the evolution of electron distribution functions in energy and L-shell phase space. We find that resonant electrons can remain trapped by the low-m ULF waves under strong convection electric  field, whereas for high-m ULF waves, the electrons trajectories can be significantly modified. More interestingly, the electron drift frequency is close to the nonlinear trapping frequency for intermediate-m ULF waves, which corresponds to chaotic motion of resonant electrons. These  findings shed new light on the nature of particle coherent and diffusive transport in the inner magnetosphere.
Validation of Clear-Sky Global LAnd Surface Satellite (GLASS) Longwave Radiation Product
Authors: Zeng Qi , Cheng Jie , Yang Feng
Published: March 2020

Surface longwave (LW) radiation plays an important rolein global climatic change, which is consist of surface longwave upward radiation (LWUP), surface longwave downward radiation (LWDN) and surface longwave net radiation (LWNR). Numerous studies have been carried out to estimate LWUP or LWDN from remote sensing data, and several satellite LW radiation products have been released, such as the International Satellite Cloud Climatology Project‐Flux Data (ISCCP‐FD), the Global Energy and Water cycle Experiment‐Surface Radiation Budget (GEWEX‐SRB) and the Clouds and the Earth’s Radiant Energy System‐Gridded Radiative Fluxes and Clouds (CERES‐FSW). But these products share the common features of coarse spatial resolutions (100-280 km) and lower validation accuracy.

Under such circumstance, we developed the methods of estimating long-term high spatial resolution all sky  instantaneous LW radiation, and produced the corresponding products from MODIS data from 2000 through 2018 (Terra and Aqua), named as Global LAnd Surface Satellite (GLASS) Longwave Radiation product, which can be free freely downloaded from the website (http://glass.umd.edu/Download.html).

In this article, ground measurements collected from 141 sites in six independent networks (AmerciFlux, AsiaFlux, BSRN, CEOP, HiWATER-MUSOEXE and TIPEX-III) are used to evaluate the clear-sky GLASS LW radiation products at global scale. The bias and RMSE is -4.33 W/m2 and 18.15 W/m2 for LWUP, -3.77 W/m2 and 26.94 W/m2 for LWDN, and 0.70 W/m2 and 26.70 W/m2 for LWNR, respectively. Compared with validation results of the above mentioned three LW radiation products, the overall accuracy of GLASS LW radiation product is much better. We will continue to improve the retrieval algorithms and update the products accordingly.
Experimental Access to Volcanic Processes
Authors: Dingwell Donald B.
Published: March 2020

Volcanism, and its underlying magmatic origins, are key elements of the Earth System. Their central role can be summed up in the convention that a planet without volcanism is classified as dead. The scientific investigation of the origins, nature and impact of volcanic eruptions is currently one of the most vibrant areas of the solid earth sciences. Observation and quantification of volcanism is greatly assisted by its very nature which includes solid earth processes at the planetary surface and whose dynamics occur on observable timescales. Thus time and location work in our favour. Working against us however is the generally highly energetic, often highly violent, explosive nature of volcanism which frequently precludes deep access to eruptive processes during their operation. Here, the investigation of eruptive processes, together with their causes and consequences, has been greatly assisted by experimental approaches.

Highlights of the experimental investigation of volcanism have included the following:

1) The geochemical diversity of magma, together with its highly variable phase state, yield a very wide range of magmatic properties which form the basis for much of the variety of volcanic expression.

2) The eruptive products of volcanism present a wide range of types of information on the nature of volcano dynamics that can be calibrated with experimental methods.

3) The fate and influence of volcanic materials in the Earth System, whose investigation is often accessible via highly novel experiments,  provide a rich palette of impacts that have likely made the presence of volcanism on Earth a defining element in the atmosphere, hydrosphere, biosphere and elsewhere.

Experimental volcanology has a rich future...  
Biogeochemical response to tropical cyclone Hudhud in the Bay of Bengal using an ocean-biogeochemical coupled model
Authors: Vivek Seelanki , Nigam Tanuja , Pant Vimlesh
Published: March 2020

It is challenging to study the surface and sub-surface oceanic physical and biogeochemical response in the intense weather conditions like tropical cyclones (TC). Due to limitation of observed subsurface data, most of the studies utilize satellite measured parameters to examine the response of ocean to a passing cyclone. The Bay of Bengal (BoB) is a semi landlocked basin in the northeastern Indian Ocean. The supply of freshwater from rivers and precipitation cause a shallow mixed layer and warmer sea surface temperature leading to cyclogenesis in the BoB. A few studies used in-situ Bio-Argo float which is limited to specified single point location to study oceanic response during the passage of Hudhud cyclone. The genesis of TC Hudhud in the Andaman Sea was on 6 October 2014, later it was intensified as Cyclonic Storm (CS) on 8 October and made landfall near Visakhapatnam on 12 October as an Extremely Severe Cyclonic Storm (ESCS). The TC Hudhud travelled nearly 1600 km in the ocean from genesis to landfall location. Only a few studies carried out on surface and subsurface biogeochemical response during TC Hudhud using Bio-Argo float. There is only one float located on the cyclone track. At that position, the system was a severe cyclonic storm (SCS) around wind speed was 45-55 knots. In the present study, we demonstrate the surface and subsurface bio-physical response along the track from CS to ESCS of TC Hudhud using a fully coupled ecosystem (ocean-biogeochemical) model. The model is configured using Regional Ocean Modeling System (ROMS) coupled with Bio-fennel. The model well captures the variability of surface and subsurface features of biogeochemical and physical parameters like chlorophyll concertation, dissolved oxygen, nutrients and temperature, salinity to compare with Bio-Argo float, and satellite data. Analysis shows that TC Hudhud induced upwelling cause intense water mixing which has a substantial impact on biological processes from depth of oxycline, nutricline to the upper-ocean layer. The model results are further analyzed to understand upper-oceanic physical and biological processes for the pre- and post-cyclone periods and their along-track variations. Model simulation shows changes in subsurface chlorophyll maximum, oxycline, nutricline and chlorophyll blooms with the passage of TC Hudhud in the BoB. The physical and biological processes are discussed to explain the observed and modelled variations in the upper-ocean characteristics.
Reconstructing floods in small-medium scale data-scarce catchments using field interview data and hydrodynamic modelling
Authors: Malgwi Mark Bawa , Ramirez Jorge Alberto , Zischg Andreas , Zimmermann Markus , Schürmann Stefan , Keiler Margreth
Published: March 2020

We develop a technique for reconstructing floods in small-scale data scarce regions using field interview data and hydro-dynamic modelling. The field interview data consist of flood depths and duration data collected from 300 buildings from a flood event in 2017 in Suleja/Tafa area, Nigeria. The flood event resulted from an overflow of water from five river reaches. The hydrodynamic model utilized, called CAESER LisFLOOD, is an integration of a landscape evolution model (CAESER) and a hydraulic model (LisFLOOD-FP). We employ three steps to reconstruct the 2017 Suleja/Tafa flood event. Firstly, we use a linearly increasing hydrograph to; (a) calibrate Manning’s coefficient and (b) determine optimal peak discharge on each reach. This was carried out by minimizing the Root Mean Square Error (RMSE) between the distributed observed flood depths and the simulated flood depths. Secondly, we use synthetic hydrographs with durations between 6, 12, 18, 20, 24 hours, having peak discharge (extracted from the previous step), to simulate flows on all upstream reaches. Using collected flood duration data, we minimized RMSE between distributed observed flood duration and simulated flood duration to determine optimal flow durations on each upstream reach. In the last step, utilizing peak discharge and flow duration for all upstream reaches, we carried out multiple spatial and temporal iterations to match downstream peak discharge. Thereafter, we use determined upstream hydrographs with their relative catchment response timing to simulate the entire river network. Minimum RMSE computed for the entire river network was between ±15 cm of many current studies that use distributed observed data to calibrate flood models. The method developed in this study is useful for simulating floods in regions where data such as high resolution DEMs, river bathymetry and river discharge are limited. In addition, the study extends current knowledge, on utilizing distributed flood data to determine peak discharge, from a single to multiple river networks.
Implement of JW ecological technology to an area under heavy rainfall
Authors: Yeh Hund-Der , Ma Kuo-Chen , Chan Tze-Y , Chuang Mo-Hsiung
Published: March 2020

Floods and droughts are exacerbated due to global warming and climate change. Heavy rainfall often leads to serious flooding events. How to improve traditional methods for storm sewer system design or alternative measures therefore has become an important issue in Taiwan. The objective of this study is to use the SWMM module to simulate the use of the JW eco-technology (JWET) in an area under different heavy rainfall resulting in surface runoff and infiltration. A small region in a city in north Taiwan is selected as the target area for the simulations and the results are compared with the flood potential map produced based on the simulation results from the SOBEK model developed by Deltares System for river, urban or rural management. The low-impact development module of the SWMM is chosen to simulate the spatial distributions of surface runoff and infiltration using the JWET in the target area under different heavy rainfall intensities. The results show that the implement of JWET to the target area can effectively reduce surface runoff and significantly increase surface infiltration and groundwater recharge. In other words, the implement of JWET to an urban area can achieve the objective of environmental adaptation and reduce the loss of people's lives and property.

 

Keywords: heavy rainfall; low impact development; JW ecological technology
Characterization of turbulent magnetic reconnection in solar flares with microwave imaging spectroscopy
Authors: Fleishman Gregory , Gary Dale , Chen Bin , Yu Sijie , Kuroda Natsuha , Nita Gelu
Published: March 2020

Magnetic reconnection plays a central role in highly magnetized plasma, for example, in solar corona. Release of magnetic energy due to reconnection is believed to drive such transient phenomena as solar flares, eruptions, and jets. This energy release should be associated with a decrease of the coronal magnetic field. Quantitative measurements of the evolving magnetic field strength in the corona are required to find out where exactly and with what rate this decrease takes place. The only available methodology capable of providing such measurements employs microwave imaging spectroscopy of gyrosynchrotron emission from nonthermal electrons accelerated in flares. Here, we report microwave observations of a solar flare, showing spatial and temporal changes in the coronal magnetic field at the cusp region; well below the nominal reconnection X point. The field decays at a rate of ~5 Gauss per second for 2 minutes. This fast rate of decay implies a highly enhanced, turbulent magnetic diffusivity and sufficiently strong electric field to account for the particle acceleration that produces the microwave emission. Moreover, spatially resolved maps of the nonthermal and thermal electron densities derived from the same microwave spectroscopy data set allow us to detect the very acceleration site located within the cusp region. The nonthermal number density is extremely high, while the thermal one is undetectably low in this region indicative of a bulk acceleration process exactly where the magnetic field displays the fast decay. The decrease in stored magnetic energy is sufficient to power the solar flare, including the associated eruption, particle acceleration, and plasma heating. We discuss implications of these findings for understanding particle acceleration in solar flares and in a broader space plasma context.
A Tarim-South China-North India connection in the periphery of Rodinia: Constraints from provenance of middle Neoproterozoic sedimentary rocks in the Altyn Tagh orogen, southeastern Tarim
Authors: Liu Qian
Published: March 2020

Locating Tarim during assembly and breakup of Supercontinent Rodinia remains enigmatic, with different models advocating a Tarim-Australia linkage or a location between Australia and Laurentia at the heart of unified Rodinia. In this study, zircon U-Pb dating results first revealed middle Neoproterozoic sedimentary rocks in the Altyn Tagh orogen, southeastern Tarim. These sedimentary rocks were deposited between ca. 880 and 750 Ma in a rifting-related setting slightly prior to breakup of Rodinia at ca. 750 Ma. A compilation of Neoproterozoic geological records indicates that the Altyn Tagh orogen in southeastern Tarim underwent ca. 1.0-0.9 Ga collision and ca. 850-600 Ma rifting related to assembly and breakup of Rodinia, respectively. In order to place Tarim in Rodinia, available detrital zircon U-Pb ages and Hf isotopes from Meso- to Neoproterozoic sedimentary rocks in relevant Rodinia blocks are compiled. Comparable detrital zircon ages (at ca. 0.9, 1.3-1.1, and 1.7 Ga) and Hf isotopes indicate a close linkage among southeastern Tarim, Cathaysia, and North India, but rule out a North or West Australian affinity for Tarim. In addition, detrital zircons from northern Tarim exhibit a prominent age peak at ca. 830 Ma with minor spectra at ca. 1.9 and 2.5 Ga but lack Mesoproterozoic ages, which are comparable to those from northern and western Yangtze. Together with comparable geological responses to assembly and breakup of Rodinia, a new Tarim-South China-North India connection is inferred in the periphery of Rodinia.
Research on Error Correction and Integration Methods of Maximum and Minimum Temperature Forecast Based on Multi –model in arid area
Authors: lihong Jia
Published: March 2020

It is very difficult to predict accurate temperature, especially for maximum and minimum temperature, due to the large diurnal temperature range in arid area. Based on the temperature forecast products from ECMWF, T639, DOGRAFS and GRAPES models and hourly temperature observations at 105 automatic weather stations in Xinjiang during 2013~2015, two kinds of error correction and integration schemes were designed by using the decaying averaging method, ensemble average and weighted ensemble average method, the effects of error correction and integration on predicted maximum and minimum temperature in fore seasons in different partitions Xinjiang were tested contrastively. The first scheme was integrating forecast temperature before correcting errors, while the second scheme was correcting forecast errors firstly and then giving an integration. The results are follows as: (1)The accuracy of temperature predictions from ECMWF model was the best in Xinjiang as a whole, while that from DOGRAFS model was the worst, and the improvement to minimum temperature predictions was higher than that of maximum temperature prediction. (2) With regarding to different partitions Xinjiang, the accuracies of predicted maximum and minimum temperature in northern Xinjiang, west region and plain areas were correspondingly higher than those in southern Xinjiang, east region and mountain areas, and the correction capability to temperature prediction in winter was higher than that in other seasons. (3) The integrated prediction of maximum and minimum temperature by weighted ensemble average method was better than that of ensemble average method. The second scheme was superior to the first scheme. (4) The improvement to maximum(minimum) temperature prediction in the extreme high(low) temperature event process from 13 to 30 July 2017(from 22 to 24 April 2014) in Xinjiang was significant by using the second scheme.
Appraisal of the process-based analytical derivation approach in calculating the probability distribution of annual runoff in different watersheds
Authors: Guo Shuhui
Published: March 2020

In this paper, the process-based analytical derivation approach is applied to insight into the nonstationary of the probability distribution of annual runoff in humid and arid watersheds of China. The nonstationary of the runoff generation process in watersheds are captured by the hydrological inputs and model parameters of the process-based analytical derivation approach. The results indicate that climate change and human activities can impact the probability distribution of annual runoff in different ways, for the nonstationary analysis of humid watersheds, climate change leads to changes in hydrological inputs, and human activities leads to changes in model parameters, which leads to nonstationary of the probability distribution of annual runoff. For the nonstationary analysis of arid watersheds, climate change leads to changes in hydrological inputs, the combined action of human activities with climate change leads to changes in model parameters, which leads to nonstationary of the probability distribution of annual runoff.
New Predictive Model for Relative Permeability of Deformable Gas Hydrate-Bearing Sediments
Authors: Lei Gang , Liao Qinzhuo , Shirish Patil
Published: March 2020

Global energy demand is expected to grow significantly as the world population and the standard of living increase in the coming decades. As a potential source of energy, gas hydrate, which is a crystalline compound of gas-water mixture formed in stable of high pressure and low temperature, has been intensively investigated in the past few decades. In this work, a new analytical model is derived to study the effect of hydrate saturation on stress-dependent relative permeability behavior of hydrate-bearing sediments. The proposed relative permeability model solves the steady-state Navier-Stokes equations for gas-water two-phase flow in porous media with hydrates. It considers water saturation, hydrate saturation, viscosity ratio and hydrate-growth pattern, and is adequately validated with the experimental results in existing literatures. The model demonstrates that gas-water relative permeability in wall coating hydrates (WC hydrates) is larger than that in pore filling hydrates (PF hydrates). For WC hydrates, water phase relative permeability monotonically decreases as gas saturation increases. However, for PF hydrates, water phase relative permeability firstly increases and then decreases with the increase of gas saturation, which can be explained by the “lubricative” effect of the gas phase that exists between the water phase and hydrates. This work constitutes a comprehensive investigation of stress-dependent relative permeability in deformable hydrate-bearing sediments, which is a key issue for sustainable gas production. It not only provides theoretical foundations for quantifying relative permeability in hydrate-bearing sediments, but also can be used to estimate pore-scale parameters and rock lithology of gas hydrate-bearing sediments using inverse modeling.
Urban dry island effect and its potential underlying mechanisms in the Yangtze River Delta urban agglomeration, China
Authors: Li Baoni
Published: March 2020

Land use/cover change (LUCC) affects regional climate change not only through its direct changes of land surface properties, but also through its further modifications of land-atmosphere interactions including the surface energy budget, water cycle and carbon cycle. Urban land expansion as a typical case of LUCC, has been widely discussed about its effects on regional climate, notably on temperature and known for urban heat island (UHI). Another important climate variable atmospheric humidity is also seriously affected by LUCC but has not earned as much attention as temperature. We examined atmospheric humidity changes by a series of indicators in the Yangtze River Delta urban agglomeration of China during 1965-2017, and found obvious urban dry land (UDI) effect in the urban cores, as characterized by decreased humidity and increased vapor pressure deficit. Furthermore, we found similar spatial patterns of humidity changes with urban land expansion process and strong correlations of humidity changes with evapotranspiration and leaf area index changes, indicating that LUCC affects regional climate through an ecohydrological way. We suggest that the UDI effect should be paid more attention in future urban planning and landscape design and more quantitative estimations of urban expansion effect on regional and global drying trends are needed.
Quantifying the Influences of Various Ecological Factors on Land Surface Temperature of Urban Forests
Authors: Ren Yin , Deng Luying , Zuo Shudi , Song Xiaodong , Liao Yinlan , Xu Chengdu , Chen Qi , Hua Lizhong , Li Zhengwei
Published: March 2020

Identifying factors that influence the land surface temperature (LST) of urban forests can help improve simulations and predictions of spatial patterns of urban cool islands. This requires a quantitative analytical method that combines spatial statistical analysis with multi-source observational data. The purpose of this study was to reveal how human activities and ecological factors jointly influence LST in clustering regions (hot or cool spots) of urban forests. Using Xiamen City, China from 1996 to 2006 as a case study, we explored the interactions between human activities and ecological factors, as well as their influences on urban forest LST. Population density was selected as a proxy for human activity. We integrated multi-source data (forest inventory, digital elevation models (DEM), population, and remote sensing imagery) to develop a database on a unified urban scale. The driving mechanism of urban forest LST was revealed through a combination of multi-source spatial data and spatial statistical analysis of clustering regions. The results showed that the main factors contributing to urban forest LST were dominant tree species and elevation. The interactions between human activity and specific ecological factors linearly or nonlinearly increased LST in urban forests. Strong interactions between elevation and dominant species were generally observed and were prevalent in either hot or cold spots areas in different years. In conclusion, quantitative studies based on spatial statistics and GeogDetector models should be conducted in urban areas to reveal interactions between human activities, ecological factors, and LST.
Inversion of detrital zircon data to constrain spatially varying erosion rates
Authors: De Doncker Fien , Herman Frédéric , Fox Matthew
Published: March 2020

Landscapes evolve through surface processes that are often transient in space and time. To understand the underlying geomorphic processes, one must assess how erosion rates vary spatially. This can be done using provenance analysis. Here, we introduce a formal inversion method to derive erosion patterns using detrital zircon age data as fingerprints. Zircons are omnipresent in Earth’s crust and contain information about the time since (re)crystallization in their U/Th-Pb ratio. For each geological unit having undergone a specific tectonic or magmatic history, one can find a unique age-frequency signature. Hence, erosion and sedimentation of grains originating from diverse source areas lead to a mix of the varying age-frequency signatures in sediments found at the outlet of a catchment. Considering that the age signal is not altered during erosion-transportation-deposition events, and given that recent technological advances enable precise dating of large amounts of grains, U/Th-Pb zircon ages provide an appropriate fingerprinting tool. Our inversion approach relies on the least-squares method with a priori information and model covariance to deal with non-uniqueness. We show with synthetic and natural examples that we are able to retrieve erosion rate patterns of a catchment when the age distribution for each geological unit is well known. Furthermore, relying on the nested form of catchments and their subcatchments, we demonstrate that adding samples taken at the outlet of subcatchments improves the estimation of erosion rate patterns. We conclude that the least squares inverse model applied on detrital zircon data has great potential for investigating erosion rates.
Quantifying the probability distribution function of the Transient Climate Response to Cumulative CO2 Emissions
Authors: Spafford Lynsay , MacDougall Andrew
Published: March 2020

The Transient Climate Response to Cumulative CO2 Emissions (TCRE) is the proportionality between global temperature change and cumulative CO2 emissions. The TCRE implies a finite quantity of CO2 emissions, or carbon budget, consistent with a given temperature change limit. The uncertainty of the TCRE is often assumed be normally distributed, but this assumption has yet to be validated. We calculated the TCRE using a zero-dimensional ocean diffusive model and a Monte-Carlo error propagation (n=10 000 000) randomly drawing from probability density functions of the climate feedback parameter, the land-borne fraction of carbon, effective ocean diffusivity, radiative forcing from an e-fold increase in atmospheric CO2 concentration, and the ratio of sea to global surface temperature change. The calculated TCRE has a positively skewed distribution, ranging from 1.1-2.9 K EgC-1 (5-95% confidence), with a mean and median value of 1.9 K EgC-1 and 1.8 K EgC-1. The calculated distribution of the TCRE is well described by a log-normal distribution. The CO2-only carbon budget compatible with 2°C warming is 1 100 PgC, ranging from 700-1 800 PgC (5-95% confidence) estimated using a simplified model of ocean dynamics. Climate sensitivity (climate feedback) is the most influential Earth system parameter on the TCRE, followed by the land-borne fraction of carbon, radiative forcing from an e-fold increase in CO2, effective ocean diffusivity, and the ratio of sea to global surface temperature change. While the uncertainty of the TCRE is considerable, the use of a log-normal distribution may improve estimations of the TCRE and associated carbon budgets.
Gravity aspects from recent Earth gravity model EIGEN 6C4 for geoscience and archaeology in Sahara, Egypt
Authors: Klokocnik Jaroslav , Cilek Vaclav , Kostelecky Jan , Bezdek Ales
Published: March 2020

A new method to detect paleolakes via their gravity signal is presented (here with implications for geoscience and archaeology). The gravity aspects or descriptors (gravity anomalies/disturbances, second radial derivatives, strike angles and virtual deformations) were computed from the global static combined gravity field model EIGEN 6C4 for an application in archaeology and geoscience in Egypt and surrounding countries. The model consists of the best now available satellite and terrestrial data, including gradiometry from the GOCE mission. EIGEN 6C4 has the ground resolution ~10 km. From archaeological literarure we took the positions of archaeological sites of the Holocene occupations between 8500 and 5300 BC (8.5-5.3 ky BC) in the Eastern Sahara, Western Desert, Egypt. We correlated the features found from the gravity data with the locations; the correlation is good, assuming that the sites were mostly at paleolake boarders or at rivers. We suggest position, extent and shape of a paleolake. Then, we have estimated a possible location, extent and shape of the putative paleolake(s). We also reconsider the origin of Libyan Desert glass (LDG) in the Great Sand Sea (GSS) and support a hypothesis about an older impact structure created in GSS, repeatedly filled by water, which might be a part of some of the possible paleolake(s).
A Land Imaging Architecture Scorecard to Support Decision-Making
Authors: Vadnais Carolyn , Dale Erin , Wu Zhuoting
Published: March 2020

Investment decisions on land imaging data buys, partnering opportunities, technologies, and system acquisition are becoming increasingly complex as the number of Earth-observing satellites increases rapidly, aircraft sensors and unmanned aerial system platforms improve, the community of data providers and users grows, and the pace of technology development, computing, and data storage expansion accelerates. Building on a growing foundation of user needs, the USGS is developing an architecture scorecard system comparing capabilities to user needs to meet the following objectives:  (1) help identify gaps in meeting needs, (2) evaluate proposed and notional land imaging architectures, and (3) study the evolution of enterprise-wide land imaging capability as existing systems reach end of life and new systems become available over timescales of years to a decade. This flexible evaluation system can adapt to changing land imaging needs and capabilities and will evolve from an early, basic capacity to support near-term decisions to increasingly higher fidelity to enable more comprehensive and precise assessments under conditions of increasing complexity. The system will support the evaluation of land imaging systems as standalone capabilities or as suites of capabilities, beginning with a core architecture and expanding to supporting and proposed capabilities. It will be easily adaptable to different evaluative frameworks such as societal benefit areas, organizations, departmental strategic goals and objectives, and technologies (e.g., lidar, radar, optical, satellite, or aircraft).
Preliminary Results of Simulation of SOCRATES period with Global System for Atmospheric Modeling
Authors: Khairoutdinov Marat , Bretherton Christopher
Published: March 2020

The global version of the cloud-resolving System for Atmospheric Modeling (SAM) is used to simulate the global evolution of clouds and precipitation during the SOCRATES field campaign In Feb 2018 with particular focus on the Southern Ocean storm track region. The model has nonuniform horizontal resolution, which ranges from 4-km horizontal grid spacing over the Tropics up to 2-3 km isotropic grid-spacing over mid-latitudes. It includes a realistic topography and comprehensive land-surface model. The sea-surface temperature and sea ice are prescribed from observations. The results of two types of simulations are presented, weather-forecasting and observed-weather-nudged over 24-hour time scale; for the latter, hourly ERA5 reanalysis dataset is used. The cloud properties are compared to the SOCRATES observations. The sensitivity of the results to the choice of cloud microphysics, from simple single-moment to double-moment, is also discussed.
Heavy metal distribution and bioaccumulation ability in marine organisms from coastal regions of Hainan and Zhoushan, China
Authors: Hao Zhe , Wang Chenglong , Zou Xinqing
Published: March 2020

In this study, we analyzed the distribution and bioaccumulation of six heavy metals (Cu, Pb, Zn, Cr, Cd, Hg) in marine organisms from China’s Hainan and Zhoushan coastal regions. Across all marine organism samples, as well as sediment and seawater samples, Zn and Hg ranked highest and lowest in concentration, respectively. Heavy metal distributions in the marine organisms varied by region and species; concentrations were higher (except for Zn) in Zhoushan than in Hainan and in crab than in fish. A marine organism’s ability to digest and eliminate heavy metals (bioaccumulation ability), based on bioaccumulation factors, was significantly higher for heavy metals in seawater than in sediment; higher sediment background values may explain the higher heavy metal concentrations in crab. In general, a marine organism’s bioaccumulation ability was higher for Cu and Zn and lower for Pb in China.
Monitoring and analysis of geological hazards based on loading impact change
Authors: Wang Wei , Zhang Chuanyin , Hu Minzhang , Yang Qiang
Published: March 2020

Monitoring is essential to the prevention and control of geological hazards, yet conventional monitoring is often conducted for local geological hazards, and the relation between monitored results and geological hazards remains poorly understood. In this study, regional load deformation field model was constructed based on data from Continuously Operating Reference Stations (CORS). The relation between load-induced changes and geological hazards, as the Regular Characteristics (RCS), are obtained by comparing the geological hazards with the impact of the total load change in the whole region. Geological hazards are more prone to occurring when there are one or more RCS, especially abnormal dynamic environment appear at the same time, such as solid high tide, heavy rainfall, and so on. The RCS included the ground geodesy height change rate increasing, the ground gravity change rate decreasing, the ground vertical deviation diverging, the ground geodesy height gradient growing larger, and the ground gravity gradient growing larger. It was found that the comprehensive observations of CORS and gravity stations can effectively monitor the RCS of the load-induced changes. The results of this study provide more insights associated with the geological hazards monitoring and analysis methods as well as effective support for geological hazard forecasting.
A Cloud Platform and Hybrid Positioning Method for Indoor Location Service
Authors: Mi Jinzhong , Li Dehai , Liu Xiao
Published: March 2020

In order to deal with the discontinuity and deficient availability of indoor positioning, a private cloud platform of location service was built in this paper, and a hybrid positioning technology was realized. In this platform, dynamic deployment, elastic computing, and on-demand cloud computing services was implemented by the hardware resource virtualization. The limits in large users online service and data communication were overcome by utilizing microservices management and its cloud-push-service component. In the hybrid cloud positioning, a method of beacon node correction and autonomous trajectory estimation was proposed. This method could improve continuity and usability of indoor positioning, and reach a positioning accuracy of 2m approximately. At last, by integrating indoor map and hybrid indoor positioning, the cloud software and terminal application had been developed for public location service.
The spatio-temporal characteristics of forest fires in China: observations from hybrid remote sensing data
Authors: Fang Lei , Qiao Zeyu , Yang Jian
Published: March 2020

Forest fire is a natural disaster threatening global human well-beings as well as a crucial disturbance agent driving forest landscape changes. The remotely sensed burned area (BA) products can provide spatially and temporally continuous monitoring of global fires, but the accuracies remain to be improved. We firstly developed a hybrid burned area mapping approach, which integrated the advantages of a 250 m global BA product (CCI_Fire) and a 30 m global forest change (GFC) product, to generate an improved 250 m BA product (so-called CCI_GFC product). Based on 248 fire patches derived from Landsat imagery, the results showed that the CCI_GFC product improved the CCI_Fire product substantially, which are significantly better than MCD64A1 product. According to the CCI_GFC, we found the total BA in the past 17 years was about 12.1 million ha in China, which approximately covered 6.1% of the total forested areas with a significantly decreased trend through Mann-Kendall test (Tau= -0.47, P<0.05) . We conducted a grid analysis (0.05°×0.05°) to determine the hot spots of forest fire from 2001 to 2017. We also quantified fire characteristics on frequency, spatial distribution, and seasonality in terms of Burned Forest Rate (BFR), hot spot areas, and fire seasons, respectively. We found that low frequency burns with a 0<BFR≤20% in 17 years covered 64% of total grids; the medium-low frequency burns (20%<BFR≤40%), the medium frequency burns (40%<BFR≤60%), the medium-high frequency burns (60%< BFR≤80%) accounted for 15%, 7%, 4% respectively; the high frequency burns (80%<BFR≤100%) and extremely high burns (100%<BFR≤120%) together occupy 10% of total grids which mainly distributed in Xiao Hinggan mountains, south China, and southwest China. The seasonality of forest fires differed substantially among eco-regions. The fire seasons of two temperate forest eco-regions are spring and autumn. The two peak fire months are May and October, in which about 22% and 37% of the total burned area were founded respectively. As a comparison, fire seasons in tropical and subtropical eco-regions are spring and winter (i.e., November to March of the next year), which accounted 88% of the total burned area. Our study clearly illustrated the characteristics of forest fire patterns in the past 17 years, which highlighted the remarkable achievements due to a nationwide implementation of fire prevention policy. At the same time, we emphasized that it is critically important to regard the long-term forest fire dynamics to design scientific and reasonable strategies or methods for fire management and controlling, which will be of sound significance to optimize the allocation of financial resources on fire management, and to achieve sustainable management of forests.
A numerical study of convection initiation in Southwestern Xinjiang, Northwest China
Authors: Ming Jie , Abulikemu Abuduwaili
Published: March 2020

Convection initiation (CI)  occurred near the oasis region surrounded by gobi desert in the Southwestern Xinjiang, Northwest China is investigated using a real-data, high-resolution Weather Research and Forecasting (WRF) simulation. Observations revealed that many CIs occurred successively near oasis region, some of which developed significantly in both size and intensity and eventually become a strong mesoscale convective system (MCS). The WRF simulation captured the general features of the CIs and MCS. Lagrangian vertical momentum budgets were conducted along the backward trajectories of air parcels within three convective cells. The total vertical acceleration was decomposed into dynamic and buoyant components. The results showed that the buoyant acceleration played a decisive role for about half of the air parcels during the CI, which was contributed by the dry air buoyancy. However, the dynamic acceleration mainly contributed during the CI for about one fourth of the air parcels. The dynamic acceleration can be further decomposed into five terms based on anelastic approximation. The positive dynamic acceleration was mainly caused by the vertical twisting term associated with the mid-level vertical shear, while the extension term contributed negatively to the dynamic acceleration. The other two terms related to horizontal curvature and height variation of density were negligibly small.