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地球科学前沿：英文版

地球科学前沿：英文版

本刊涉及领域包括地质学、岩石矿物矿床学、构造地质学、古生物学及地层学（含沉积学）、地震地质学、地球化学、地球物理学、地貌学及第四纪地质学、水文地质、工程地质与环境地质学、找矿勘探与地质工程、海洋地质、地理学、地图学与地理信息系统、地球探测与信息技术等。
  • 发文量：527
  • 被引量：151
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  • 开始收录时间：2012,6(1)
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  • 国内刊号/CN：11-5982/P
    国际刊号/ISSN：2095-0195
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    邮发代号：80-963
  • 主管单位：中华人民共和国教育部
    主办单位：高等教育出版社
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地球科学前沿：英文版 >2023年第2期

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  • 摘要：Gaofen-3(GF-3)is the first Chinese spaceborne multi-polarization synthetic aperture radar(SAR)instrument at C-band(5.43 GHz).In this paper,we use data collected from GF-3 to observe Super Typhoon Lekima(2019)in the East China Sea.Using a VH-polarized wide ScanSAR(WSC)image,ocean surface wind speeds at 100m horizontal resolution are obtained at 21:56:59 UTC on 8 August 2019,with the maximum wind speed,38.9 m·s^(-1).Validating the SAR-retrieved winds with buoymeasured wind speeds,we find that the root mean square error(RMSE)is 1.86 m·s^(-1),and correlation coefficient,0.92.This suggests that wind speeds retrieved from GF-3 SAR are reliable.Both the European Centre for MediumRange Weather Forecasts(ECMWF)fine grid operational forecast products with spatial resolution,and China Global/Regional Assimilation and Prediction Enhance System(GRAPES)have good performances on surface wind prediction under weak wind speed condition(24m·s^(-1)).With respect to SAR-retrieved wind speeds,the RMSEs are 5.24 m·s^(–1) for ECMWF and 5.17 m·s^(–1) for GRAPES,with biases of 4.16 m·s^(–1) for ECMWF and 3.84 m·s^(-1)for GRAPES during Super Typhoon Lekima(2019).
  • 摘要：Along with conventional methods,this paper proposed a method in which ID and 3D models are integrated to identify the self-sourced reservoir potential of the Farewell Formation in the Kupe Gas Field within the Taranaki Basin,New Zealand.Source rock characteristics were evaluated at both field and basin scales by investigating source rock maturity,type of organic matter,and hydrocarbon generation potential by rock pyrolysis,using Rock-Eval 2 and 6.The ID thermal and burial history model established the rate of sedimentation and thermal history of the Kupe 4 well.Reservoir characterization at field-scale was determined by seismic interpretation,well log analysis,and 3D structural and petrophysical models.The sediments of the Farewell Formation contain types Ⅱ-Ⅲ(oil/gas prone)and type Ⅲ(gas prone)and have fair-to-excellent generation potential.The oxygen and hydrogen indices ranged from 3 to 476 mg C0_(2)/g TOC and 26 to 356 mg HC/g TOC,respectively,whereas the thermal maturity determined by vitrinite reflectance values ranged between 0.3%and 0.72%,indicating that the Farewell Formation is in immature-to-mature hydrocarbon generation stage.Thus,Farewell Formation was verified to be a good source rock.Additionally,structural interpretations demonstrated the structural complexity of an extensional and contractional regime within the reservoir package.Multiple faults indicated a good reservoir property there with a trapping mechanism as well as migration paths.A well-log-based petrophysical analysis established the presence of up to 70%hydrocarbon saturation within the pore spaces of Farewell sandstones.The 3D models confirmed that the Farewell Formation has significant sand zones and hydrocarbon-saturated zones,thereby proving its very good reservoir characteristics.It has been proved that the ID and 3D structural schemes,integrated with geological techniques,was vital in identifying the Kupe Field as a self-sourced reservoir.
  • 摘要：It is of great significance to quantitatively assess the impact of mountain precipitation on inland river runoff in data scarce regions.Based on the corrected TRMM precipitation and runoff data,a variety of statistical methods were used to identify which areas of precipitation have an important impact on runoff in the Hotan River Basin,and to evaluate the effects that precipitation changes have on runoff at low,mid,high,and extremely high altitudes of mountainous areas.The results showed that:1)From 1998 to 2015,the annual runoff showed a fluctuating upward trend with a rate of 11.21×10^8 m^3/10 a(P<0.05).Runoff in every season also had an increasing trend,with summer runoff the most significant at a rate of 6.09×10^8 m^3/10 a.2)The annual runoff and precipitation changes had certain synchronization,with a correlation coefficient of 0.45(P<0.05).Among them,the correlations between precipitation and runoff changes were highest at low and mid-altitudes,with coefficients of 0.62 and 0.55,respectively(P<0.05).3)65.95%of the regional precipitation at low altitudes and 48.34%at high altitudes were significantly correlated with runoff(P<0.05),while only 38.84%and 26.58%of regional precipitation levels at mid-and extremely high altitudes were significantly correlated with runoff.4)The annual precipitation change in the basin was 1%,which would cause the annual runoff to change by 0.24%.In 1998-2015,the change of annual runoff caused by precipitation change at high altitudes was largest at a rate of−6.01%;the change rates of annual runoff caused by precipitation change in the low,mid-,and extremely high altitudes were−3.66%,−3.62%,and−3.67%,respectively.The results have significant scientific guidance for water resource management in arid basins.
  • 摘要：The pore structure of continuous unconven-tional reservoirs(CURs)in coal measures was investigated using different technologies for 29 samples(9 coal samples,9 shale samples,and 11 sandstone samples)from Qinshui Basin,China.Results show that coals have relatively high porosities and permeabilities ranging from 4.02%to 5.19%and 0.001 to 0.042 mD,respectively.Micropores(50 nm).However,shales are characterized by poorly petrophysical properties with low porosity and permeability.Macropores and mesopores(2-50 nm)are well-developed in shales compared with micropores.For coals,abundant organic matters are expected to promote the development of micropores,and clay minerals significantly control the performance of mesopores.For shales and sandstones,micropores are mainly observed in organic matters,whereas clay minerals are the important contributor to mesopores.Moreover,micropore SSA significantly deter-mines the adsorption capacity of CURs and sandstones have the best pore connectivity.The permeability of CURs is positively associated with the macropore PV since macropores serve as the main flow paths for gas seepage.Additionally,we also proposed that effective porosity has a significant effect on the permeability of CURs.The findings of this study could enhance the understanding of the multiscale pore structure of CURs and provide insights into the mechanisms that control gas storage,transport,and subsequent co-production for continuous unconventional natural gas(CUNG)in the Qinshui Basin and other coal-bearing basins worldwide.
  • 摘要：This study undertook verification of the applicability and accuracy of wind data measured using a WindCube V2 Doppler Wind Lidar(DWL).The data were collected as part of a field experiment in Zhoushan,Zhejiang Province(China),which was conducted by Shanghai Typhoon Institute of China Meteorological Administration during the passage of Super Typhoon Lekima(2019).The DWL measurements were compared with balloon-borne GPS radiosonde(GPS sonde)data,which were acquired using balloons launched from the DWL location.Results showed that wind speed measured by GPS sonde at heights of100 m)was found for DWL-measured wind speed time-averaged during the ascent of the GPS sonde from the ground surface to the height of 270 m(correlation coefficient:0.82;root mean square(RMS):2.19 m·h^(-1)).Analysis revealed that precipitation intensity(PI)exerts considerable influence on both the carrier-to-noise ratio and the rate of missing DWL data;however,PI has minimal effect on the wind speed bias of DWL measurements.Specifically,the rate of missing DWL data increased with increasing measurement height and PI.For PI classed as heavy rain or less(PI90 m·h^(-1)),only data below 100 m were valid.Up to the height of 300 m,the RMS of the DWL measurements was nearly half that of wind profile radar(WPR)estimates(4.32 m·s^(-1)),indicating that DWL wind data are more accurate than WPR data under typhoon conditions.
  • 摘要：The impact of vertical resolution on the simulation of Typhoon Lekima(2019)is investigated using the Weather Research and Forecasting(WRF)model version 3.8.1.Results show that decreasing vertical grid spacing from approximately 1000 m to 100 m above 1 km height barely influences the simulated track.However,significant differences are found in the simulated tropical cyclone(TC)structure.The simulation with the coarsest vertical resolution shows a clear double warm-core structure.The upper warm core weakens and even disappears with the increase of vertical resolution.A broader eye and a more slantwise eyewall are observed with the increase of vertical resolution due to the vertically extended lower-level and upper-level outflow,which likely results in a weaker subsidence.Vertical grid convergence is evaluated with the simulated kinetic energy(KE)spectra.As the vertical grid spacing becomes finer than 200 m,convergent KE spectra are found in both the free atmosphere and the outer core of the TC.However,sensitivity tests reveal that the grid convergence is sensitive to the choice of the planetary boundary layer scheme.
  • 摘要：The predictions for Super Typhoon Lekima(2019)have been evaluated from official forecasts,global models,regional models and ensemble prediction systems(EPSs)at lead times of 1–5 days.Track errors from most deterministic forecasts are smaller than their annual mean errors in 2019.Compared to the propagation speed,the propagation direction of Lekima(2019)was much easier to determine for the official agency and numerical weather prediction(NWP)models.The National Centers for Environmental Prediction Global Ensemble Forecast System(NCEP-GEFS),Japan Meteorological Agency Global Ensemble Prediction System(JMA-GEPS)and Meteorological Service of Canada Ensemble System(MSC-CENS)are underdispersed,and the Shanghai Typhoon Institute Typhoon Ensemble Data Assimilation and Prediction System(STI-TEDAPS)is overdispersed,while the ensemble prediction system from European Centre for Medium-Range Weather Forecasts(ECMWF)shows adequate dispersion at all lead times.Most deterministic forecasting methods underestimated the intensity of Lekima(2019),especially for the rapid intensification period after Lekima(2019)entered the East China Sea.All of the deterministic forecasts performed well at predicting the first landfall point at Wenling,Zhejiang Province with a lead time of 24 and 48 h.
  • 摘要：Human activity transforms a land surface into a complex surface where artificial and natural landforms coexist and continuous and emergent landforms merge.In this background,the problems of conventional digital elevation models(DEMs),such as morphological distortion,complicated updates,and lack of information,are increasingly prominent.This study proposes a new idea of DEM construction based on the concept of geographic ontology.First,landforms with common features are abstracted into a certain type of topographic entity based on their morphologies and semantics.For each type of topographic entity,a DEM was constructed independently based on the available elevation information and other information about the semantics and spatial relationships.Second,individual DEMs were merged into a complete DEM following certain rules.A 1 km2 area located in the suburb of Nanjing,Jiangsu Province,China,was selected as the experimental area.The effectiveness of the model construction method proposed in this study was verified.The results show that the DEM constructed according to the idea of this study has a significantly better performance than the conventional DEMs.The constructed DEM in this study can well represent ground objects,such as slopes,farmland,and ditches.In particular,the constructed DEM ensures the morphological accuracy of the ground objects.
  • 摘要：This study of vegetation dynamics in the coastal region of Tanzania provides a fundamental basis to better understand the nature of the factors that underlie observed changes.The Tanzanian coast,rich in biodiversity,is economically and environmentally important although the understanding of the nature and causes of vegetation change is very limited.This paper presents an investigation of the relationship between vegetation dynamics in response to climate variations and human activities using Moderate Resolution Imaging Spectro-radiometer(MODIS),Normalized Difference Vegetation Index(NDVI),meteorological,and Globeland30 Landsat data sets.Spatio-temporal trends and the relationship of NDVI to selected meteorological variables were statistically analyzed for the period 2000-2018 using the Mann-Kendall test and Pearson correlation respectively.The results reveal a significant positive trend in temperature(/?>0,Z=2.87)and a non-significant trend in precipitation(|Z|<1.96).A positive relationship between NDVI and precipitation is observed.Coastal Tanzania has therefore experienced increased temperatures and variable moisture conditions which threaten natural vegetation and ecosystems at large.Classified land cover maps obtained from GlobeLand30 were analyzed to identify the nature and scale of human impact on the land.The analysis of land use and land cover in the region reveals an increase in cultivated land,shrubland,grassland,built-up land and bare land,while forests,wetland and water all decreased between 2000 and 2020.The decrease in forest vegetation is attributable to the fact that most livelihoods in the region are dependent on agriculture and harvesting of forest products(firewood,timber,charcoal).The findings of this study highlight the need for appropriate land-use planning and sustainable utilization of forest resources.
  • 摘要：Calibration error is one of the primary sources of bias in echo intensity measurements by ground-based radar systems.Calibration errors cause data discontinuity between adjacent radars and reduce the effectiveness of the radar system.The Global Precipitation Measurement Kuband Precipitation Radar(GPM KuPR)has been shown to provide stable long-term observations.In this study,GPM KuPR observations were converted to S-band approximations,which were then matched spatially and temporally with ground-based radar observations.The measurements of stratiform precipitation below the melting layer collected by the KuPR during Typhoon Ampil were compared with those of multiple radar systems in the Yangtze River Delta to determine the deviations in the echo intensity between the KuPR and the ground-based radar systems.The echo intensity data collected by the ground-based radar systems was corrected using the KuPR observations as reference,and the correction results were verified by comparing them with rain gauge observations.It was found that after the correction,the consistency of the echo intensity measurements of the multiple radar systems improved significantly,and the precipitation estimates based on the revised ground-based radar observations were closer to the rain gauge measurements.
  • 摘要：To investigate the paleoenvironmental controls on organic matter accumulation of Upper Paleozoic shales in the eastern Ordos Basin,China,26 shale samples were collected from two wells drilled into the Shanxi and Taiyuan Formations.The total organic carbon(TOC)content,mineral compositions and elemental geochemistry of the samples were analyzed.Quartz(35.42%)and clay minerals(48.34%)are the dominant minerals and trace elements(Li,Cs,Cu,V,Co,and Cr)are commonly enriched in the shale samples compared to the Upper Continental Crust.C-values(ranging from 0.2 to 4.5),chemical indices of weathering(CIW)values(48.82 to 99.11),and Sr/Cu ratios(1.00 to 11.05)suggest that the paleoclimate was humid in the study area during the Late Paleozoic.Elemental redox indices(e.g.,Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3)),V/Cr,Ni/Co,V/(V+Ni)and U/Th)indicate a dysoxic to oxic paleoenvironment characterized by transi-tional sedimentary deposits in a continental margin setting.In addition,chemical index of alteration(CIA,ranging from 77.92%to 98.36%)and CIW(89.19%to 99.11%)values suggest that there was intense chemical weathering in the study area,while the Al_(2)O_(3)-CaO^(*)+Na_(2)O-K_(2)O(A-CN-K)ternary diagram demonstrates that the shales were not subjected to potassium metasomatism during diagen-esis.Al_(2)O_(3)/TiO_(2)and TiO_(2)/Zr ratios,as well as REE characteristics suggest a felsic source rocks and discount seawater as an REE source.Ce anomalies indicate an oxic environment with terrigenous input during black shale deposition,and LREE enrichment with negative Eu anomalies suggests that both shale formations were affected by detrital input rather than hydrothermal fluids.The correlation of TOC(ranging from 1.10%to 6.39%,with an average of 2.77%)with trace elemental redox indices(Sr/Cu,Sr/Ba,V/Cr,and U/Th)indicates that a warm-humid,dysoxic to oxic environment preserved much of the organic matter.
  • 摘要：To visualize and analyze the impact of uncertainty on the geological subsurface,on the term of the geological attribute probabilities(GAP),a vector parameters-based method is presented.Perturbing local data with error distribution,a GAP isosurface suite is first obtained by the Monte Carlo simulation.Several vector parameters including normal vector,curvatures and their entropy are used to measure uncertainties of the isosurface suite.The vector parameters except curvature and curvature entropy are visualized as line features by distributing them over their respective equivalent structure surfaces or concentrating on the initial surface.The curvature and curvature entropy presented with color map to reveal the geometrical variation on the perturbed zone.The multiple-dimensional scaling(MDS)method is used to map GAP isosurfaces to a set of points in lowdimensional space to obtain the total diversity among these equivalent probability surfaces.An example of a bedrock surface structure in a metro station shows that the presented method is applicable to quantitative description and visualization of uncertainties in geological subsurface.MDS plots shows differences of total diversity caused by different error distribution parameters or different distribution types.
  • 摘要：The risk of wind waves in a bay is often overlooked,owing to the belief that peninsulas and islands will inhibit high waves.However,during the passage of a tropical cyclone,a semi-enclosed bay is exposed to twodirectional waves:one generated inside the bay and the other propagated from the outer sea.Typhoon Faxai in 2019 resulted in the worst coastal disaster in Tokyo Bay in the last few decades.The authors conducted a post-disaster survey immediately after this typhoon.Numerical modeling was also performed to reveal the mechanisms of unusual high waves.No significant high-wave damage occurred on coasts facing the Pacific Ocean.By contrast,Fukuura-Yokohama,which faces Tokyo Bay,suffered overtopping waves that collapsed seawalls.To precisely reproduce multi-directional waves,the authors developed an extended parametric typhoon model,which was embedded in the JMA mesoscale meteorological model(JMA-MSM).The peak wave height was estimated to be 3.4 m off the coast of Fukuura,in which the contribution of the outer-sea waves was as low as 10%–20%.A fetchlimited wave developed over a short distance in the bay is considered the primary mechanism of the high wave.The maximum wave occurred on the left-hand side of the typhoon track in the bay,which appears to be contrary to the common understanding that it is safer within the semicircle of a storm than on the opposite side.Typhoon Faxai was a small typhoon;however,if the radius was tripled,it is estimated that the wave height would exceed 3 m over the entire bay and surpass 4 m off the coasts of Yokohama and Chiba.
  • 摘要：In 2019,the operational Global Regional Assimilation and Prediction System-Tropical Cyclone Model(GRAPES-TCM)was updated by adopting the characteristic parameters in the official real-time released TC data of CMA,introducing the horizontal sixth-order diffusion scheme and adjusting the operational flowchart.In the case of the Super Typhoon Lekima,the model exhibits a reliable prediction ability for the type of tropical cyclone(TC)with northwestern tracking.The track and intensity forecasts in 2019 are significantly better than those over the past five years on average.The updated model can provide a skillful forecast of landfall position and rapid weakening process.Moreover,the precipitation pattern is close to the observation.TC forecast in 2019 shows that the updated GRAPES-TCM has a smaller track error than that of the previous year,and the 24 h intensity forecasting ability is improved.
  • 摘要：Strike and dip are essential to the description of geological features and therefore play important roles in 3D geological modeling.Unevenly and sparsely measured orientations from geological field mapping pose problems for the geological modeling,especially for covered and deep areas.This study developed a new method for estimating strike and dip based on structural expansion orientation,which can be automatically extracted from both geological and geophysical maps or profiles.Specifically,strike and dip can be estimated by minimizing an objective function composed of the included angle between the strike and dip and the leave-one-out cross-validation strike and dip.We used angle parameterization to reduce dimensionality and proposed a quasi-gradient descent(QGD)method to rapidly obtain a near-optimal solution,improving the time-efficiency and accuracy of objective function optimization with the particle swarm method.A synthetic basin fold model was subsequently used to test the proposed method,and the results showed that the strike and dip estimates were close to the true values.Finally,the proposed method was applied to a real fold structure largely covered by Cainozoic sediments in Australia.The strikes and dips estimated by the proposed method conformed to the actual geological structures more than those of the vector interpolation method did.As expected,the results of 3D geological implicit interface modeling and the strike and dip vector field were much improved by the addition of estimated strikes and dips.
  • 摘要：The sandstone of the third member of the Funing Formation(E1f3)in the northern slope zone of the Gaoyou Sag has the typical characteristics of high porosity and ultralow permeability,which makes it difficult for oil to flow.In this study,the lithological characteristics,sedimentary facies,diagenetic characteristics,pore struc-ture,and seepage ability of this sandstone are characterized in detail.Correlation analysis is used to reveal the reason for the sandstone high porosity-low permeability phenom-enon in the study area.The results indicate that this phenomenon is controlled mainly by the following three factors:1)the sedimentary environment is the initial affecting factor,whereby the deposition of a large number of fine-grained materials reduces the primary pores of sandstone.2)The Funing Formation has undergone strong compaction and cementation,which have led to the removal of most of the primary pores and a reduction in size of the throat channels.3)Owing to fluid activity during the later stage of diagenesis,sandstone underwent intense dissolution and a large number of particles(feldspar and lithic debris)formed many dissolution pores(accounting for nearly 60%of the total pore space).Among these factors,dissolution has contributed the most to the development of high porosity-low permeability phenomenon.This is mainly attributed to the inhomogeneous dissolution process,whereby the degree of particle dissolution(e.g.feldspar)exceeds that of cementing minerals(clay and carbonate minerals).The secondary dissolution pores have increased the porosity of sandstone in the study area;however,the pore connectivity(permeability)has not been significantly improved,thus resulting in the special high porosity-low permeability characteristics of this sandstone.
  • 摘要：This paper uses pollen climate analysis and coexistence analysis to systematically analyze the climatic evolution of the Shahejie Formation in the Chezhen Depression,Bohai Bay Basin,eastern China and discusses the relationship between palaeoclimatic evolution and lake level rise.The results show that the sedimentary period of the Shahejie Formation in the Chezhen Depression had an overall temperature change trend from hot to cold and simultaneously experienced a dry and wet balance-wet-dry and wet balance-wet transition process.The climatic parameters of the Shahejie Formation in the Chezhen Depression include a mean annual temperature of 8.1℃-15.1℃,a mean coldest monthly temperature of-0.1℃-2℃,a mean warmest monthly temperature of 18.6℃-28℃,a mean annual precipitation of 389-1164 mm,a wettest monthly precipitation amount of 215-262 mm,and a driest monthly precipitation amount of 8-48 mm.Climate change is believed to affect the rise and fall of lake levels to some extent.The quantitative reconstruction of these climatic parameters allows researchers to more intuitively understand the geological background of the Chezhen Depression and guide the exploration and development of oil and gas resources.
  • 摘要：Typhoon Lekima(2019)struck Zhejiang Province on 10 August 2019 as a supertyphoon,which severely impacted Zhejiang Province.The typhoon killed 45 people and left three others missing,and the total economic loss reached 40.71 billion yuan.This paper reports a postdisaster survey that focuses on the storm precipitation,flooding,landslides,and weather services associated with Typhoon Lekima(2019)along the southeastern coastline of Zhejiang Province.The survey was conducted by a joint survey team from the Shanghai Typhoon Institute and local meteorological bureaus from 26 to 28 August,2019,approximately two weeks after the disaster.Based on this survey and subsequent analyses of the results,we hope to develop countermeasures to prevent future tragedies.
  • 摘要：As one of the most devastating tropical cyclones over the western North Pacific Ocean,Super Typhoon Lekima(2019)has caused a wide range of heavy rainfall in China.Based on the CMA Multi-source merged Precipitation Analysis System(CMPAS)-hourly data set,both the temporal and spatial distribution of extreme rainfall is analyzed.It is found that the heavy rainfall associated with Lekima includes three main episodes with peaks at 3,14 and 24 h after landfall,respectively.The first two rainfall episodes are related to the symmetric outburst of the inner rainband and the persistence of outer rainband.The third rainfall episode is caused by the influence of cold,dry air from higher latitudes and the peripheral circulation of the warm moist tropical storm.The averaged rainrate of inner rainbands underwent an obvious outburst within 6 h after landfall.The asymmetric component of the inner rainbands experienced a transport from North(West)quadrant to East(South)quadrant after landfall which was related to the storm motion other than the Vertical Wind Shear(VWS).Meanwhile the outer rainband in the vicinity of three times of the Radius of Maximum Wind(RMW)was active over a 12-h period since the decay of the inner rainband.The asymmetric component of the outer rainband experienced two significant cyclonical migrations in the northern semicircle.
  • 摘要：Tropical hurricanes are among the most devastating hazards on Earth.Knowledge about its intense inner-core structure and dynamics will improve hurricane forecasts and advisories.The precise morphological parameters extracted from high-resolution spaceborne Synthetic Aperture Radar(SAR)images,can play an essential role in further exploring and monitoring hurricane dynamics,especially when hurricanes undergo amplification,shearing,eyewall replacements and so forth.Moreover,these parameters can help to build guidelines for wind calibration of the more abundant,but lower resolution scatterometer wind data,thus better linking scatterometer wind fields to hurricane categories.In this paper,we develop a new method for automatically extracting the hurricane eyes from C-band SAR data by constructing Gray Level-Gradient Co-occurrence Matrices(GLGCMs).The hurricane eyewall is determined with a two-dimensional vector,generated by maximizing the class entropy of the hurricane eye region in GLGCM.The results indicate that when the hurricane is weak,or the eyewall is not closed,the hurricane eye extracted with this automatic method still agrees with what is observed visually,and it preserves the texture characteristics of the original image.As compared to Du’s wavelet analysis method and other morphological analysis methods,the approach developed here has reduced artefacts due to factors like hurricane size and has lower programming complexity.In summary,the proposed method provides a new and elegant choice for hurricane eye morphology extraction.
  • 摘要：A validated particle flow code(PFC^(2D))-based model was developed to investigate the indirect tensile mechanical behavior of shale containing two central parallel cracks under Brazilian splitting test conditions.The results show that preexisting cracks have a significant and insignificant influence on the tensile strength of shale under LPL and LVL conditions,respectively.When L≥10 mm,changing the L and H values has little effect on the tensile strength of shale.However,the inclusion of preexisting cracks have a positive effect on reducing the anisotropy of the shale specimens,and in the case of an L/D ratio of 0.3,the shale anisotropy is the lowest.Four failure modes were formed at differentβandθvalues under LPL conditions.In the case ofβ≥60°,the failure mode is mainly affected byβ,and whenβ≤45°,the failure mode is more complicated than in the case ofβ≥60°.Only three major failure modes were observed under LVL conditions;in the case of 45°≤β≤75°andθ≤30°,the most complex failure mode occurred.
  • 摘要：淡水海藻的花蕾成为了世界范围的一颗成长担心。他们被 cyanobacteria 的高水平引起，主要 Microcystis spp。并且 Cylindrospermopsis raciborskii，它能分别地生产 microcystin 和 cylindrospermopsin。到这些 cyanotoxins 的长期的暴露可以影响这些有害水藻种类的公共健康，这样可靠的察觉， quantification，和枚举在水质量管理成为了优先级。海藻的花蕾房间的传统的用手的枚举首先包含由不确和 time-consumption.With 限制了分子的技术和在 Genbank 数据库可得到的越来越多的微生物引起的序列的开发的显微镜的鉴定，分子的方法的使用能被用于更多的快速、可靠、精确的察觉和 quantification。在这，学习，复合聚合酶链反应(PCR ) 和即时量的 PCR (qPCR ) 技术被开发并且申请了监视 cyanobacteria Microcystis spp。并且 C。在澳门存储水库(MSR ) 的 raciborskii。结果证明这些技术为识别并且确定是成功的在纯文化的种类并且混合了文化，并且证明了是为在 MSR 的水采样的一个潜在的应用程序。当目标种类在 100 万 cells/L 上面时，类似的房间数字由显微镜的枚举估计了， qPCR 被获得。在水样品的进一步的 quantification 显示由显微镜学和 qPCR 的房间的估计的数字的比率为 C 是为 cyanobacteria 和 0.2-3.9 的 0.4-12.9。raciborskii。然而， Microcystis spp。当它被 qPCR 在底层检测时，没被用手的枚举观察，建议 qPCR 更敏感、精确。因此，分子的途径提供一种另外的可靠监视选择给传统的显微镜的枚举因为监视的生态系统编程序[出版摘要]
  • 摘要：The stability of dawsonite is an important factor affecting the feasibility evaluation of CO_(2)geological storage.In this paper,a series of experiments on the interaction of CO_(2)-water-dawsonite-bearing sandstone were carried out under different CO_(2)pressures.Considering the dissolution morphology and element composition of dawsonite after the experiment and the fluid evolution in equilibrium with dawsonite,the corrosion mechanism of dawsonite led by CO_(2)partial pressure was discussed.The CO_(2)fugacity of the vapor phase in the system was calculated using the Peng-Robinson equation of state combined with the van der Waals 1-fluid mixing rule.The experimental results indicated that the thermodynamic stability of dawsonite increased with the increase of CO_(2)partial pressure and decreased with the increase of temperature.The temperature at which dawsonite dissolution occurred was higher at higher f_(CO_(2)).There were two different ways to reduce dawsonite’s stability:the transformation of constituent elements and crystal structure damage.Dawsonite undergoes component element transformation and crystal structure damage under different CO_(2)pressures with certain temperature limits.Based on the comparison of the corrosion temperature of dawsonite,three corrosion evolution models of dawsonite under low,medium,and high CO_(2)pressures were summarized.Under conditions of medium and low CO_(2)pressure,as the temperature continued to increase and exceeded its stability limit,the dawsonite crystal structure was corroded first.Then the constituent elements of dawsonite dissolved,and the transformation of dawsonite to gibbsite began.At high CO_(2)pressure,the constituent elements of dawsonite dissolved first with the increase of temperature,forming gibbsite,followed by the corrosion of crystalline structure.
  • 摘要：The establishment of the National Key Ecological Function Areas(NKEFAs)is an important measure for national ecological security,but the current ecological and environmental evaluation of NKEFAs lacks research on the air quality in the NKEFAs.This study presented the current status of the air quality in the NKEFAs and its driving factors using the geographic detector q-statistic method.The air quality in the NKEFAs was overall better than individual cities and urban agglomeration in eastern coast provinces of China,accounting for 9.21%of the days with air quality at Level III or above.The primary air pollutant was PM_(10),followed by PM_(2.5),with lower concentrations of the remaining pollutants.Pollution was more severe in the sand fixation areas,where air pollution was worst in spring and best in autumn,contrasting with other NKEFAs and individual cities and urban agglomerations.The main influencing factors of air quality index(AQI)in the NKEFAs were land use type,wind speed,and relative humidity also weighted more heavily than factors such as industrial pollution and anthropogenic emissions,and most of these influence factors have two types of interactive effects:binary and nonlinear enhancements.These results indicated that air pollution in the NKEFAs was not related with the emission by intensive economic development.Thus,the policies taking the NKEFAs as restricted development zones were effective,but the air pollution caused by PM_(10) also showed the ecological status in the NKEFAs,especially at sand fixation areas was not quite optimistic,and more strict environmental protection measures should be taken to improve the ecological status in these NKEFAs.
  • 摘要：Three-dimensional(3D)reconstruction of the equivalent pore network model(PNM)using X-ray computed tomography(CT)data are of significance for studying the CO_(2)-enhanced coalbed methane recovery(CO_(2)-ECBM).The docking among X-ray CT technology,MATLAB,with COMSOL software not only can realize the 3D reconstruction of PNM,but also the CO_(2)-ECBM process simulation.The results show that the Median filtering algorithm enabled the de-noising of the original 2D CT slices,the image segmentation of all slices was realized based on the selected threshold,and the PNM can be constructed based on the Maximum Sphere algorithm.The mathematical model of CO_(2)-ECBM process fully coupled the expanded Langmuir equation.At the same time for CO_(2)injection,CH_(4)pressure tends to decrease with the increase of CO_(2)pressure,but its difference is not obvious.The CH_(4)pressure in the slice center changed a lot,while at the edge it changed a little under different CO_(2)pressures.The injected CO_(2)was transported to matrix along the macro and micro-fractures with continuous flow.The injected CO_(2)first replaced the adsorbed CH_(4)by covering the inner surface of macro-pores and meso-pores to form the single molecular layer adsorption of CO_(2).Then they migrated to micro-pores by Fick’s diffusion,sliding flow,and surface diffusion.Furthermore,the CO_(2)replaced CH_(4)adsorbed by volumetric filling in micro-pores,and formed the multi-molecular layer adsorption of CO_(2).The gas pressure and migration path between CO_(2)and CH_(4)are opposite.This study can provide a theoretical basis for studying digital rock physics technology and enrich the development of CO_(2)-ECBM technology.
  • 摘要：Over the past 2000 years,a high-resolution pollen record from the Yushenkule Peat(46°45′-46°57′N,90°46′-90°61′E,2374 m a.s.l.)in the south-eastern Altai Mountains of northwestern China has been used to explore the changes in vegetation and climate.The regional vegetation has been dominated by alpine meadows revealed from pollen diagrams over the past 2000 years.The pollen-based climate was warm and wet during the Roman Warm Period(0-520 AD),cold and wet during the Dark Age Cold Period(520-900 AD),warm and wet during the Medieval Warm Period(900-1300 AD),and cold and dry during the Little Ice Age(1300-1850 AD).Combined with other pollen data from the Altai Mountains,we found that the percentage of arboreal pollen showed a reduced trend along the NW-SE gradient with decreasing moisture and increasing climatic continentality of the Altai Mountains over the past 2000 years;this is consistent with modern distributions of taiga forests.We also found that the taiga(Pinus forest)have spread slightly,while the steppe(Artemisia,Poaceae and Chenopodiaceae)have recovered significantly in the Altai Mountains over the past 2000 years.In addition,the relatively warm-wet climate may promote high grassland productivity and southward expansion of steppe,which favors the formation of Mongol political and military power.
  • 摘要：Fracture system is an important factor controlling tight oil accumulation in the Triassic Chang 8 Member,southwestern Ordos Basin,China.A systematic characterization of the multi-scale natural fractures is a basis for the efficient tight oil production.Based on outcrops,seismic reflections,well cores,well logs(image and conventional logging),casting thin sections,and scanning electron microscope observation,the multi-scale fractures occurrences and their influences on Chang 8 tight sandstone reservoirs are revealed.The results show that three periods of strike-slip faults and four scales of natural fractures developed,namely mega-scale(length>7×10^(7) mm),macro-scale(3.5×10^(5)
  • 摘要：A varied class method is applied to calculate the effective discharges and their variations after the Three Gorges Dam(TGD)construction based on the mean daily flow discharge and suspended sediment concentration field data from 1981 to 2016.For comparison,the bankfull discharges are also determined according to the cross-section profiles and flow discharge-stage relations.Our results show that a bimodal effective discharge curve usually exists at the fixed sites,which generates two effective discharges(Q_(e1) and Q_(e2))within the moderate flow range.Under the quasi-equilibrium circumstances of the pre-dam period,effective discharges are closely related to the mean annual runoff,with a narrow range of regional variations in occurrence frequency.Our analyses draw the conclusion that the relatively higher unsaturation degrees of the pre-dam effective discharges caused by dam interception and riverbed coarsening are the primary cause of the increase in effective discharges from Yichang to Shashi,while the more frequent low and medium discharges due to flow regulation drive the decrease in effective discharges from Jianli to Datong.The slightly elevated flood levels and descending bankfull levels collaboratively result in the decrease of bankfull discharges from Yichang to Shashi,while the lowered bed elevation causes the increase in bankfull discharges from Luoshan to Datong.Overall,the bankfull discharge in the Middle and Lower Yangtze River is larger than effective discharge and approaches the 1.5-year recurrence interval discharge.
  • 摘要：Forecasting the intensity of typhoons is a difficult problem in numerical weather prediction.It is subject to many factors,among which the selection of physical parameterization schemes for the model is a hot topic of research.In this study,the effects of horizontal mixing length(represented by h_diff)and planetary boundary layer(PBL)schemes were investigated.Six idealized and four operational sensitivity experiments were designed based on simulation of the typhoon Lingling,which occurred over the western Pacific in 2019,using the Hurricane Weather Research and Forecasting model.The results of the idealized experiments showed that,as h_diff was increased,the slope of the typhoon eye area also increased,and its intensity became stronger.On the other hand,the results of the sensitivity experiments indicated that the intensity of the simulated typhoon was sensitive to the choice of PBL scheme,with the forecast bias of the QNSE(Quasi-Normal Scale Elimination)scheme being smaller than that of the GFDL(Geophysical Fluid Dynamics Laboratory)scheme.Angular momentum budget analyses indicated that,when increasing the h_diff,the convergence of angular momentum was larger in the boundary layer,which led to a faster spin-up of the vortex,further increasing the intensity of the typhoon.From the calculated horizontal and vertical vortex spread it was found that,when the h_diff was increased,the corresponding horizontal and vertical diffusion eddies also showed an increasing trend,which was also the reason for the strengthening of the typhoon.Meanwhile,the forecast bias decreased significantly with increasing horizontal mixing length when using the same PBL scheme.
  • 摘要：Global maps of bioclimatic variables currently exist only at very coarse spatial resolution(e.g.WorldClim).For ecological studies requiring higher resolved information,this spatial resolution is often insufficient.The aim of this study is to estimate important bioclimatic variables of Mongolia from Earth Observation(EO)data at a higher spatial resolution of 1 km.The analysis used two different satellite time series data sets:land surface temperature(LST)from Moderate Resolution Imaging Spectroradiometer(MODIS),and precipitation(P)from Climate Hazards Group Infrared Precipitation with Stations(CHIRPS).Monthly maximum,mean,and minimum air temperature were estimated from Terra MODIS satellite(collection 6)LST time series product using the random forest(RF)regression model.Monthly total precipitation data were obtained from CHIRPS version 2.0.Based on this primary data,spatial maps of 19 bioclimatic variables at a spatial resolution of 1 km were generated,representing the period 2002-2017.We tested the relationship between estimated bioclimatic variables(SatClim)and WorldClim bioclimatic variables version 2.0(WorldClim)using determination coefficient(R^(2)),root mean square error(RMSE),and normalized root mean square error(nRMSE)and found overall good agreement.Among the set of 19 WorldClim bioclimatic variables,17 were estimated with a coefficient of determination(R^(2))higher than 0.7 and normalized RMSE(nRMSE)lower than 8%,confirming that the spatial pattern and value ranges can be retrieved from satellite data with much higher spatial resolution compared to WorldClim.Only the two bioclimatic variables related to temperature extremes(i.e.,annual mean diurnal range and isothermality)were modeled with only moderate accuracy(R^(2) of about 0.4 with nRMSE of about 11%).Generally,precipitation-related bioclimatic variables were closer correlated with WorldClim compared to temperature-related bioclimatic variables.The overall success of the modeling was attributed to the fact that satellite-derived data are well suited to generated spatial fields of precipitation and temperature variables,especially at high altitudes and high latitudes.As a consequence of the successful retrieval of the bioclimatic variables at 1 km spatial resolution,we are confident that the estimated 19 bioclimatic variables will be very useful for a range of applications,including species distribution modeling.

    地球科学前沿：英文版的期刊信息

    • 曾用名：中国高等学校学术文摘·地球科学
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