This study utilized census data from Henan Province for the years 2000,2010,and 2020 to investigate the spatiotemporal evolution of population aging,defined by the proportion of the population aged 65 and above.Employ...This study utilized census data from Henan Province for the years 2000,2010,and 2020 to investigate the spatiotemporal evolution of population aging,defined by the proportion of the population aged 65 and above.Employing spatial analysis techniques such as spatial autocorrelation and the standard deviation ellipse,the research mapped out the progression and distribution of aging demographics.Furthermore,the study delved into the influencing factors of aging using an optimal parameters-based geographical detector.Results indicate a deepening degree of population aging in Henan Province,transitioning from an adult type to an old type structure.There is a marked positive spatial correlation among counties,with high-value aging areas initially decreasing,then increasing,and notably spreading from the central to the central and southern regions of the province.The center of gravity for population aging,specifically around Changge City and Xuchang City,exhibits a trajectory moving southeast before shifting northwest.Factor detection reveals that in 2000,2010,and 2020,the elderly dependency ratio predominantly influences the aging trend,with explanatory powers of 88.4%,87.9%,and 90.9%,respectively.Interaction analysis indicates that the interaction between the old-child ratio and the elderly dependency ratio has a strong explanatory power for the aging patterns in Henan Province,reaching 97.3%,97.0%,and 97.4%,respectively.展开更多
Several deficiencies exist in the present evaluation of land reclamation quality in mining areas.These include the absence of an established set of evaluation index systems and standard acceptance criteria,as well as ...Several deficiencies exist in the present evaluation of land reclamation quality in mining areas.These include the absence of an established set of evaluation index systems and standard acceptance criteria,as well as the use of traditional sam-pling techniques,which are costly and in eficiency,and time-consuming.Compared with the traditional sampling survey methods,remote sensing has the advantages of a wide detection range,diverse information collection,multiple data-acquiring strategies,high speed,and short cycle.In this study,we used the Xinzhuang coal mining field in Yongcheng,Henan Province as an example to extract information and invert surface parameters using remote sensing techniques,based on national and local reclamation regulations and standards.Subsequently,using remote sensing,we constructed an index system for evaluating land reclamation quality in three aspects:reclaiming project quality,soil quality,and ecological benefits.Through the grading standards of evaluation indicators and quantitative remote sensing models,we determined the extracted information on the area of indicators,roads,ditches,soil moisture,organic matter,and ecological benefits after reclamation.Based on this,we established a quality evaluation model for mining land reclamation using an improved index and method.The evaluation units were divided,and the weight of the evaluation index was determined using the analytic hierarchy process and data envelopment analysis(AHP-DEA)method.The land reclamation quality in the study area was comprehensively evaluated,field accuracy was verified,and the results were analyzed.The results show that,except for the removal of roads,houses,and fishponds in the study area,all 13 evaluation units achieved a score of 60 points or higher.The quality of reclamation met the standards,and the evaluation results were consistent with the conclusions of the field investigation and project acceptance report,demonstrating the reliability and feasibility of the method developed in this study.The research results will provide technical support for the scientific evaluation of land reclamation quality.展开更多
Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, lands...Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak. Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR （synthetic aperture radar interferometry） and D-InSAR （differential synthetic aperture radar interferometry）, supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmental background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made： （1） the multitemporal SAR magnitude images were used to interpret the geological structure, vegetation, microgeomorphology and drainage system; （2） the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and （3） the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas （sites）. In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas （sites） were obtained, belonging to those in 1993-1996, 1996-1997, 1997-1998, 1998-2001, 1998-2002 and 2001-2003 respectively. Of the 84 areas, 44 are mining subsidence ones, 23 urban subsidence ones and 17 landslide subsidence ones. They cover a total area of 1824.4 km^2, equivalent to the area of the whole Datong coalfield. Then an accurate evaluation was made on the geo-environment of the Datong coalfield. The tests show that InSAR is now the only feasible technical means for making one all-weather, real-time measurement of a coal mining land subsidence area covering up to 10,000 km^2 to subcentimeter resolution. This study is a successful application of InSAR in the investigation and evaluation of land subsidence, especially in coal mining areas.展开更多
The gravity and magnetic data can be adopted to interpret the internal structure of the Earth.To improve the calculation efficiency during the inversion process and the accuracy and reliability of the reconstructed ph...The gravity and magnetic data can be adopted to interpret the internal structure of the Earth.To improve the calculation efficiency during the inversion process and the accuracy and reliability of the reconstructed physical property models,the triple strategy is adopted in this paper to develop a fast cross-gradient joint inversion for gravity and magnetic data.The cross-gradient constraint contains solving the gradients of the physical property models and performing the cross-product calculation of their gradients.The sparse matrices are first obtained by calculating the gradients of the physical property models derived from the first-order finite difference.Then,the triple method is applied to optimize the storages and the calculations related to the gradients of the physical property models.Therefore,the storage compression amount of the calculations related to the gradients of the physical property models and the cross-gradient constraint are reduced to one-fold of the number of grid cells at least,and the compression ratio increases with the increase of the number of grid cells.The test results from the synthetic data and field data prove that the structural coupling is achieved by using the fast cross-gradient joint inversion method to effectively reduce the multiplicity of solutions and improve the computing efficiency.展开更多
Joint inversion is one of the most effective methods for reducing non-uniqueness for geophysical inversion.The current joint inversion methods can be divided into the structural consistency constraint and petrophysica...Joint inversion is one of the most effective methods for reducing non-uniqueness for geophysical inversion.The current joint inversion methods can be divided into the structural consistency constraint and petrophysical consistency constraint methods,which are mutually independent.Currently,there is a need for joint inversion methods that can comprehensively consider the structural consistency constraints and petrophysical consistency constraints.This paper develops the structural similarity index(SSIM)as a new structural and petrophysical consistency constraint for the joint inversion of gravity and vertical gradient data.The SSIM constraint is in the form of a fraction,which may have analytical singularities.Therefore,converting the fractional form to the subtractive form can solve the problem of analytic singularity and finally form a modified structural consistency index of the joint inversion,which enhances the stability of the SSIM constraint applied to the joint inversion.Compared to the reconstructed results from the cross-gradient inversion,the proposed method presents good performance and stability.The SSIM algorithm is a new joint inversion method for petrophysical and structural constraints.It can promote the consistency of the recovered models from the distribution and the structure of the physical property values.Then,applications to synthetic data illustrate that the algorithm proposed in this paper can well process the synthetic data and acquire good reconstructed results.展开更多
This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coasta...This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coastal segments of a headland-bay beach in west Guangdong, South China, and explores the physical significances of those parameters in the models. The results indicate that：（1） Bodge＇s model is more in line with the equilibrium beach profile of the tangential or transitional segment, whereas Lee＇s model is more consistent with the shadow profile;（2） most of the parameters in three models have clear physical significances in accordance with the actual characteristics of this headland-bay beach; and（3） both the selections for the equilibrium beach profile from different segments and significances of most of the parameters in three models are in essence correlated with the morphodynamic states at various coastal locations.展开更多
Beach morphodynamic classifications have achieved extensive acceptance in foreign coastal geomorphological studies. Three beaches located in different zones of a headland-bay coast are classified according to a dimens...Beach morphodynamic classifications have achieved extensive acceptance in foreign coastal geomorphological studies. Three beaches located in different zones of a headland-bay coast are classified according to a dimensionless fall parameter, a relative tide range parameter and a dimensionless embayment scaling parameter. Synchronous data, including wave, tide, sediment and beach morphology, are respectively collected from the tangential beach, the transitional beach and the shadow beach of the Shuidong Bay during each spring tide for 16 successive months. The research results indicate that （1） the beach in the tangential zone falls between two major categories which are low tide terrace beaches with rips and barred beaches; the beach in the transitional zone exhibits two main types which are low tide bar/rip beaches and barred dissipative beaches; and the beach in the shadow zone mainly mirrors dissipative states with presence or absence of bars; and （2） the sequential changes and differences of beach states in different coastal zones reflect spatial and temporal variabilities of the headland- bay coast, totally meeting the actual measured beach morphology changes, showing that studies on wave- dominated, meso-macrotidal beaches need to consider the influences of the tides. Meanwhile, the research mainly provides a framework about beach state studies, due to different beach states with different erosion patterns, which requires the need to strengthen the researches in this respect, in order to further enrich theoretical basis for a beach topography evolution, beach morphodynamic processes and beach erosion orevention in China.展开更多
Understanding the spatial interactions among multiple ecosystem services is crucial for ecosystem services management. Ecosystem services, including crop production, freshwater supply, aquatic production, net primary ...Understanding the spatial interactions among multiple ecosystem services is crucial for ecosystem services management. Ecosystem services, including crop production, freshwater supply, aquatic production, net primary production, soil conservation, water conservation, flood regulation, forest recreation, were measured at 1-km grid scale covering the Taihu Lake Basin(TLB) of China. Our objective is to get a comprehensive understanding of the spatial distributions, trade-offs, synergies of multiple ecosystem services across the TLB. Our results found that: 1) majority of ecosystem services were clustered in space and had a similar spatial distribution pattern with the geographical resource endowment. Most of the landscape contributed a high supply of no services, one or two, and a low supply of three to seven services. 2) There were high correlation between forest recreation and freshwater supply and regulating services. Aquatic production had low correlation with other services. 3) The changes of provisioning services led to trade-offs between regulating services and cultural services in the TLB, while synergies mainly occurred among the provisioning service. 4) The spatial relationships of multiple services are consistent at 1-km spatial scale, counties and provinces. This research could help integrate multiple ecosystem services across scales and serve as a reference for decision making.展开更多
Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals （nHRS）, drought tolerance and water use efficiency of winter wheat （Triticu...Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals （nHRS）, drought tolerance and water use efficiency of winter wheat （Triticum aestivum）. The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots （1.06 and 0.94 mmol g-1 s-1, respectively）. The soil water content （SWC） at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants （61.1-44.6% field water capacity） than for intact root plants （57.9-46.1% field water capacity）. At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield （F PS II ）, the maximum photochemical efficiency of PS II （F v /F m ）, coefficient of photochemical quenching （qP）, and coefficient of non-photochemical quenching （NPQ）, in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency （WUE） than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of drought- resistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.展开更多
The development of industry is inseparable from the support of mining.However,mining processes consume a large amount of energy,and increased tailing emissions can have a significant impact on the environment.In the p...The development of industry is inseparable from the support of mining.However,mining processes consume a large amount of energy,and increased tailing emissions can have a significant impact on the environment.In the past few decades,the mining industry developed many technologies that are related to mineral energy management,of which cemented paste backfill(CPB)is one of the representative technologies.CPB has been successfully applied to mine ground control and tailings management.In CPB technology,the mixing process is the key to achieving materials with good final quality and controlled properties.However,in the preparation process,the mixed homogeneity of the CPB is difficult to achieve because of fine tailings,high solid volume fraction,and high viscosity.Most research focused on the effect of mixing ingredients on CPB properties rather than on the preparation process of the CPB.Therefore,improving the performance and reducing the production cost of CPB by optimizing the mixing process are important.This review summarizes the current studies on the mixing technology of CPB and its application status in China.Then,it compares the advantages and disadvantages of multiple mixing equipment and discusses the latest results and research hotspots in paste preparation.Finally,it concludes the challenges and development trends of mixing technology on the basis of the relevant application cases in China to promoting cement-based material mixing technology development.展开更多
The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan are...The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China.Taking the Zhengzhou metropolitan area(ZZMA)as a case study,we developed an inverse S-shape model to characterize the spatial distribution of urban land density,and constructed an urban expansion core index,urban expansion intensity index,and urban compactness index to quantify the spatial structure change that has taken place from 1978 to 2017 during the process of urban expansion.Moreover,cropland contribution rate(CR)was constructed to evaluate the impacts of urban expansion on croplands.We uncovered four key findings.First,over the past 40 yr,the ZZMA has experienced dramatic expansion,and the central city of Zhengzhou expanded faster than other cities.The gravity centers of urban expansion of surrounding cities were moving toward to Zhengzhou City.Second,the urban land density decreased with the distance from the city center to the outskirts.As the only large city,Zhengzhou has experienced the fastest and most compact centralized urban expansion,especially after 2000,while other medium-and small-sized cities have experienced low-intensity decentralized expansion.Third,the urban core has been gradually expanding outward.From 1978 to 2017,the hot-zone of urban growth has moved progressively with the acceleration of urbanization.All cities except Jiaozuo had a single peak in different periods.Forth,the cities in national core grain-producing areas has higher cropland contribution rates and lower urban expansion areas,which was closely related to cropland protection.Further analysis showed that large city was relatively better positioned than smaller cities in the efficiency of their urban infrastructure and the effectiveness of wealth creation efficiency in the urbanized area could be tested in all cities,and the policy factor seemed to play an important role in the urban expansion process.展开更多
Glaciers are highly sensitive to climate change and are undergoing significant changes in mid-latitudes.In this study,we analyzed the spatiotemporal changes of typical glaciers and their responses to climate change in...Glaciers are highly sensitive to climate change and are undergoing significant changes in mid-latitudes.In this study,we analyzed the spatiotemporal changes of typical glaciers and their responses to climate change in the period of 1990-2015 in 4 different mountainous sub-regions in Xinjiang Uygur Autonomous Region of Northwest China:the Bogda Peak and Karlik Mountain sub-regions in the Tianshan Mountains;the Yinsugaiti Glacier sub-region in the Karakorum Mountains;and the Youyi Peak sub-region in the Altay Mountains.The standardized snow cover index(NDSI)and correlation analysis were used to reveal the glacier area changes in the 4 sub-regions from 1990 to 2015.Glacial areas in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions in the period of 1990-2015 decreased by 57.7,369.1,369.1,and 170.4 km^(2),respectively.Analysis of glacier area center of gravity showed that quadrant changes of glacier areas in the 4 sub-regions moved towards the origin.Glacier area on the south aspect of the Karlik Mountain sub-region was larger than that on the north aspect,while glacier areas on the north aspect of the other 3 sub-regions were larger than those on the south aspect.Increased precipitation in the Karlik Mountain sub-region inhibited the retreat of glaciers to a certain extent.However,glacier area changes in the Bogda Peak and Youyi Peak sub-regions were not sensitive to the increased precipitation.On a seasonal time scale,glacier area changes in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions were mainly caused by accumulated temperature in the wet season;on an annual time scale,the correlation coefficient between glacier area and annual average temperature was-0.72 and passed the significance test at P<0.05 level in the Karlik Mountain sub-region.The findings of this study can provide a scientific basis for water resources management in the arid and semi-arid regions of Northwest China in the context of global warming.展开更多
Fully normalized associated Legendre functions(fnALFs)are a set of orthogonal basis functions that are usually calculated by using the recurrence equation.This paper presented the applicability and universality of the...Fully normalized associated Legendre functions(fnALFs)are a set of orthogonal basis functions that are usually calculated by using the recurrence equation.This paper presented the applicability and universality of the standard forward column/row recurrence equation based on the isolated singular factor method and extended-range arithmetic.Isolating a singular factor is a special normalization method that can improve the universality of the standard forward row recurrence equation to a certain extent,its universality can up to degree hundreds.However,it is invalid for standard forward column recurrence equation.The extended-range arithmetic expands the double-precision number field to the quad-precision numberfield.The quad-precision numberfield can retain more significant digits in the operation process and express larger and smaller numbers.The extended-range arithmetic can significantly improve the applicability and universality of the standard forward column/row recurrence equations,its universality can up to degree several thousand.However,the quad-precision numberfield operation needs to occupy more storage space,which is why its operation speed is slow and undesirable in practical applications.In this paper,the X-number method is introduced in the standard forward row recurrence equation for thefirst time.With the use of the X-number method,fnALFs can be recursed to 4.2 billion degree by using standard forward column/row recurrence equations.展开更多
The estimation of potato biomass and yield can optimize the planting pattern and tap the production potential.Based on partial least square(PLSR),multiple linear regression(MLR),support vector machine(SVM),random fore...The estimation of potato biomass and yield can optimize the planting pattern and tap the production potential.Based on partial least square(PLSR),multiple linear regression(MLR),support vector machine(SVM),random forest(RF),BP neural network and other machine learning algorithms,the biomass estimation model of potato in different growth stages is constructed by using single variables such as original spectrum,first-order differential spectrum,combined spectrum index and vegetation index(VI)and their coupled combination variables.The accuracy of the models is compared and analyzed,and the best modeling method of biomass in different growth stages is selected.Based on the optimized modeling method,the biomass of each growth stage is estimated,and the yield estimation model of different growth stages is constructed based on the estimation results and the linear regression analysis method,and the accuracy of the model is verified.The results showed that in tuber formation stage,starch accumulation stage and maturity stage,the biomass estimation accuracy based on combination variable was the highest,the best modeling method was MLR and SVM,in tuber growth stage,the best modeling method was MLR,the effect of yield estimation is good.It provides a reference for the algorithm selection of crop biomass and yield models based on machine learning.展开更多
The response of vegetation productivity to precipitation is becoming a worldwide concern.Most reports on responses of vegetation to precipitation trends are based on the growth season.In the soil freeze/thaw process,t...The response of vegetation productivity to precipitation is becoming a worldwide concern.Most reports on responses of vegetation to precipitation trends are based on the growth season.In the soil freeze/thaw process,the soil water phase and heat transport change can affect root growth,especially during the thawing process in early spring.A field experiment with increased precipitation(control,increased 25%and increased 50%)was conducted to measure the effects of soil water in early spring on above-and below-ground productivity in an alpine steppe over two growing seasons from June 2017 to September 2018.The increased 50%treatment significantly increased the soil moisture at the 10 cm depth,there was no difference in soil moisture between the increased 25%treatment and the control in the growing season,which was not consistent in the freeze/thaw process.Increased soil moisture during the non-growing season retarded root growth.Increased precipitation in the freezing-thawing period can partially offset the difference between the control and increased precipitation plots in both above-and below-ground biomass.展开更多
The Medium-Resolution Spectral Imager-Ⅱ(MERSI-Ⅱ)instrument aboard China’s Fengyun-3D satellite shares similarities with NASA’s Moderate Resolution Imaging Spectroradiometer(MODIS)sensor,enabling the retrieval of g...The Medium-Resolution Spectral Imager-Ⅱ(MERSI-Ⅱ)instrument aboard China’s Fengyun-3D satellite shares similarities with NASA’s Moderate Resolution Imaging Spectroradiometer(MODIS)sensor,enabling the retrieval of global aerosol optical depth(AOD).However,no officially released operational MERSI-Ⅱ aerosol products currently exist over the ocean.This study focuses on adapting the MODIS dark target(DT)ocean algorithm to the MERSI-Ⅱ sensor.A retrieval test is conducted on the 2019 MERSI-Ⅱ data over the global ocean,and the retrieved AODs are validated against ground-based measurements from the automatic Aerosol Robotic Network(AERONET)and the shipborne Maritime Aerosol Network(MAN).The operational MODIS DT aerosol products are also used for comparison purposes.The results show that MERSI-Ⅱ AOD granule retrievals are in good agreement with MODIS products,boasting high correlation coefficients(R)of up to 0.96 and consistent spatial distribution trends.Furthermore,the MERSI-Ⅱ retrievals perform well in comparison to AERONET and MAN measurements,with high R-values(>0.86).However,the low-value retrievals from MERSI-Ⅱ tend to be slightly overestimated compared to MODIS,despite both AODs displaying a positive bias.Notably,the monthly gridded AODs over the high latitudes of the northern and southern hemispheres suggest that MERSI-Ⅱ exhibits greater stability in space and time,effectively reducing unrealistically high-value noise in the MODIS products.These results illustrate that the MERSI-Ⅱ retrievals meet specific accuracy requirements by maintaining the algorithmic framework and most of the algorithmic assumptions,providing a crucial data supplement for aerosol studies and climate change.展开更多
The comparison results of three beach profile data repeatedly measured before and after the typhoon in Shuidong Bay,west Guangdong province which show that there are significant differences in beach profile erosion an...The comparison results of three beach profile data repeatedly measured before and after the typhoon in Shuidong Bay,west Guangdong province which show that there are significant differences in beach profile erosion and response process.And the changes of beach profile can be divided into:strong downward overall low shoreline regressive type and overall slight erosion shoreline regressive type.Application of the modified mildslope equation along three beach profile are simulated wave high reflection to the sea side,to the section vertical shore pressure gradient and including water roll force and radiation stress,the vertical shore forces one dimensional profile along the momentum conservation equation(radiation stress and water roll force)bottom friction and lateral mixing reaction between numerical solution,the momentum conservation equations of the wave increases the water flow velocity and section along the profile distribution of wave height and related forces.The analysis shows that the extent and difference of coastal erosion depend on the shoreline erosion mode stimulated by the maximum surge water of the coastal current and the maximum velocity of the coastal current and the dynamic state of the profile topography under the action of the profile location,morphology and incident wave elements.展开更多
Accurate estimation of regional winter wheat yields is essential for understanding the food production status and ensuring national food security.However,using the existing remote sensing-based crop yield models to ac...Accurate estimation of regional winter wheat yields is essential for understanding the food production status and ensuring national food security.However,using the existing remote sensing-based crop yield models to accurately reproduce the inter-annual and spatial variations in winter wheat yields remains challenging due to the limited ability to acquire irrigation information in water-limited regions.Thus,we proposed a new approach to approximating irrigations of winter wheat over the North China Plain(NCP),where irrigation occurs extensively during the winter wheat growing season.This approach used irrigation pattern parameters(IPPs)to define the irrigation frequency and timing.Then,they were incorporated into a newly-developed process-based and remote sensing-driven crop yield model for winter wheat(PRYM–Wheat),to improve the regional estimates of winter wheat over the NCP.The IPPs were determined using statistical yield data of reference years(2010–2015)over the NCP.Our findings showed that PRYM–Wheat with the optimal IPPs could improve the regional estimate of winter wheat yield,with an increase and decrease in the correlation coefficient(R)and root mean square error(RMSE)of 0.15(about 37%)and 0.90 t ha–1(about 41%),respectively.The data in validation years(2001–2009 and 2016–2019)were used to validate PRYM–Wheat.In addition,our findings also showed R(RMSE)of 0.80(0.62 t ha–1)on a site level,0.61(0.91 t ha–1)for Hebei Province on a county level,0.73(0.97 t ha–1)for Henan Province on a county level,and 0.55(0.75 t ha–1)for Shandong Province on a city level.Overall,PRYM–Wheat can offer a stable and robust approach to estimating regional winter wheat yield across multiple years,providing a scientific basis for ensuring regional food security.展开更多
Synthesis of multi-satellite altimetry facilitates the acquisition of long-term changes in lake level but may induce biases due to inconsistent data sources,and thus remains largely unexplored.This study investigates ...Synthesis of multi-satellite altimetry facilitates the acquisition of long-term changes in lake level but may induce biases due to inconsistent data sources,and thus remains largely unexplored.This study investigates the integrated application of Ice,Cloud,and land Elevation Satellite(ICESat),ICESat-2,and CryoSat-2 missions to provide consecutive lake level series in 2003–2020.The sample comprises 48 lakes in the world with gauge-based or Hydroweb water level data.The CryoSat-2 data arefirst adjusted to the ICESat-2 height reference based on the mean values of their monthly water level difference during their overlapping period(2018–2020).Then,the corrected CryoSat-2 data are used to link the ICESat and ICESat-2 data.Results show that in the sample lakes,the deviations between CryoSat-2 and ICESat-2 data vary and range from-0.78 m to 0.13 m.The data quality of the synthesized time series is evaluated by comparing against the validation data,with an average R^(2) of 0.84.This study shows that CryoSat-2 has the potential offilling the gap between ICESat and ICESat-2.The three altimeters can be expected to integrate effectively for monitoring lake water level changes in the past two decades.展开更多
Soybean is one of the most important oil crops, and Argentina is the third-largest soybean producer in the world, accounting for 17% of the global soybean yield. Timely and accurate information on soybean spatial dist...Soybean is one of the most important oil crops, and Argentina is the third-largest soybean producer in the world, accounting for 17% of the global soybean yield. Timely and accurate information on soybean spatial distribution is critical for ensuring global food security. Sentinel-2 multispectral data and machine learning classification models are used to investigate the potential of soybean identification in the early stage of the growing season in Argentina, with the help of Google Earth Engine (GEE). The earliest time window and optimal feature set for soybean identification are explored. Results are as follows: 1) the random forest (RF) classification model demonstrated the highest level of classification accuracy compared to the backpropagation neural network (BPNN), support vector machine (SVM), and naive Bayes (NB) models;2) Soybean can be accurately identified as early as the end of February (filling stage), which is approximately one month before harvest;3) The optimal feature-subset can reduce the amount of input data by 80% while maintaining high classification accuracy. The overall accuracy (OA) of the RF classification model is 85.87%, and the relative error between the estimated soybean planting area and the agricultural statistics is 3.45%. This study provided a high-precision method for early-season identification of soybeans over large scales. The results can provide a data support for early futures trading and agricultural insurance, as well as a reference for policy-making to ensure global soybean food security.展开更多
基金Humanities and Social Science Project of the Ministry of Education(NO.17YJCZH041)。
文摘This study utilized census data from Henan Province for the years 2000,2010,and 2020 to investigate the spatiotemporal evolution of population aging,defined by the proportion of the population aged 65 and above.Employing spatial analysis techniques such as spatial autocorrelation and the standard deviation ellipse,the research mapped out the progression and distribution of aging demographics.Furthermore,the study delved into the influencing factors of aging using an optimal parameters-based geographical detector.Results indicate a deepening degree of population aging in Henan Province,transitioning from an adult type to an old type structure.There is a marked positive spatial correlation among counties,with high-value aging areas initially decreasing,then increasing,and notably spreading from the central to the central and southern regions of the province.The center of gravity for population aging,specifically around Changge City and Xuchang City,exhibits a trajectory moving southeast before shifting northwest.Factor detection reveals that in 2000,2010,and 2020,the elderly dependency ratio predominantly influences the aging trend,with explanatory powers of 88.4%,87.9%,and 90.9%,respectively.Interaction analysis indicates that the interaction between the old-child ratio and the elderly dependency ratio has a strong explanatory power for the aging patterns in Henan Province,reaching 97.3%,97.0%,and 97.4%,respectively.
基金supported by the National Natural Science Foundation of China (41301617)the Scientific and Technological Key Project in Henan Province (222102320005)the Key Scientific Research Project of Henan Higher Education (22A420002).
文摘Several deficiencies exist in the present evaluation of land reclamation quality in mining areas.These include the absence of an established set of evaluation index systems and standard acceptance criteria,as well as the use of traditional sam-pling techniques,which are costly and in eficiency,and time-consuming.Compared with the traditional sampling survey methods,remote sensing has the advantages of a wide detection range,diverse information collection,multiple data-acquiring strategies,high speed,and short cycle.In this study,we used the Xinzhuang coal mining field in Yongcheng,Henan Province as an example to extract information and invert surface parameters using remote sensing techniques,based on national and local reclamation regulations and standards.Subsequently,using remote sensing,we constructed an index system for evaluating land reclamation quality in three aspects:reclaiming project quality,soil quality,and ecological benefits.Through the grading standards of evaluation indicators and quantitative remote sensing models,we determined the extracted information on the area of indicators,roads,ditches,soil moisture,organic matter,and ecological benefits after reclamation.Based on this,we established a quality evaluation model for mining land reclamation using an improved index and method.The evaluation units were divided,and the weight of the evaluation index was determined using the analytic hierarchy process and data envelopment analysis(AHP-DEA)method.The land reclamation quality in the study area was comprehensively evaluated,field accuracy was verified,and the results were analyzed.The results show that,except for the removal of roads,houses,and fishponds in the study area,all 13 evaluation units achieved a score of 60 points or higher.The quality of reclamation met the standards,and the evaluation results were consistent with the conclusions of the field investigation and project acceptance report,demonstrating the reliability and feasibility of the method developed in this study.The research results will provide technical support for the scientific evaluation of land reclamation quality.
文摘Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak. Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR （synthetic aperture radar interferometry） and D-InSAR （differential synthetic aperture radar interferometry）, supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmental background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made： （1） the multitemporal SAR magnitude images were used to interpret the geological structure, vegetation, microgeomorphology and drainage system; （2） the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and （3） the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas （sites）. In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas （sites） were obtained, belonging to those in 1993-1996, 1996-1997, 1997-1998, 1998-2001, 1998-2002 and 2001-2003 respectively. Of the 84 areas, 44 are mining subsidence ones, 23 urban subsidence ones and 17 landslide subsidence ones. They cover a total area of 1824.4 km^2, equivalent to the area of the whole Datong coalfield. Then an accurate evaluation was made on the geo-environment of the Datong coalfield. The tests show that InSAR is now the only feasible technical means for making one all-weather, real-time measurement of a coal mining land subsidence area covering up to 10,000 km^2 to subcentimeter resolution. This study is a successful application of InSAR in the investigation and evaluation of land subsidence, especially in coal mining areas.
基金supported by the National Key Research and Development Program(Grant No.2021YFA0716100)the National Key Research and Development Program of China Project(Grant No.2018YFC0603502)Henan Youth Science Fund Program(Grant No.212300410105).
文摘The gravity and magnetic data can be adopted to interpret the internal structure of the Earth.To improve the calculation efficiency during the inversion process and the accuracy and reliability of the reconstructed physical property models,the triple strategy is adopted in this paper to develop a fast cross-gradient joint inversion for gravity and magnetic data.The cross-gradient constraint contains solving the gradients of the physical property models and performing the cross-product calculation of their gradients.The sparse matrices are first obtained by calculating the gradients of the physical property models derived from the first-order finite difference.Then,the triple method is applied to optimize the storages and the calculations related to the gradients of the physical property models.Therefore,the storage compression amount of the calculations related to the gradients of the physical property models and the cross-gradient constraint are reduced to one-fold of the number of grid cells at least,and the compression ratio increases with the increase of the number of grid cells.The test results from the synthetic data and field data prove that the structural coupling is achieved by using the fast cross-gradient joint inversion method to effectively reduce the multiplicity of solutions and improve the computing efficiency.
基金supported by the National Key Research and Development Program(Grant No.2021YFA0716100)the National Key Research and Development Program of China Project(Grant No.2018YFC0603502)+1 种基金the Henan Youth Science Fund Program(Grant No.212300410105)the provincial key R&D and promotion special project of Henan Province(Grant No.222102320279).
文摘Joint inversion is one of the most effective methods for reducing non-uniqueness for geophysical inversion.The current joint inversion methods can be divided into the structural consistency constraint and petrophysical consistency constraint methods,which are mutually independent.Currently,there is a need for joint inversion methods that can comprehensively consider the structural consistency constraints and petrophysical consistency constraints.This paper develops the structural similarity index(SSIM)as a new structural and petrophysical consistency constraint for the joint inversion of gravity and vertical gradient data.The SSIM constraint is in the form of a fraction,which may have analytical singularities.Therefore,converting the fractional form to the subtractive form can solve the problem of analytic singularity and finally form a modified structural consistency index of the joint inversion,which enhances the stability of the SSIM constraint applied to the joint inversion.Compared to the reconstructed results from the cross-gradient inversion,the proposed method presents good performance and stability.The SSIM algorithm is a new joint inversion method for petrophysical and structural constraints.It can promote the consistency of the recovered models from the distribution and the structure of the physical property values.Then,applications to synthetic data illustrate that the algorithm proposed in this paper can well process the synthetic data and acquire good reconstructed results.
基金financially supported by the National Natural Science Foundation of China(Grant No.41301005)Postdoctoral Science Foundation of China(Grant No.2014M552118)
文摘This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coastal segments of a headland-bay beach in west Guangdong, South China, and explores the physical significances of those parameters in the models. The results indicate that：（1） Bodge＇s model is more in line with the equilibrium beach profile of the tangential or transitional segment, whereas Lee＇s model is more consistent with the shadow profile;（2） most of the parameters in three models have clear physical significances in accordance with the actual characteristics of this headland-bay beach; and（3） both the selections for the equilibrium beach profile from different segments and significances of most of the parameters in three models are in essence correlated with the morphodynamic states at various coastal locations.
基金The National Natural Science Foundation of China under contract No.41301005the Postdoctoral Science Foundation of China under contract No.2014M552118
文摘Beach morphodynamic classifications have achieved extensive acceptance in foreign coastal geomorphological studies. Three beaches located in different zones of a headland-bay coast are classified according to a dimensionless fall parameter, a relative tide range parameter and a dimensionless embayment scaling parameter. Synchronous data, including wave, tide, sediment and beach morphology, are respectively collected from the tangential beach, the transitional beach and the shadow beach of the Shuidong Bay during each spring tide for 16 successive months. The research results indicate that （1） the beach in the tangential zone falls between two major categories which are low tide terrace beaches with rips and barred beaches; the beach in the transitional zone exhibits two main types which are low tide bar/rip beaches and barred dissipative beaches; and the beach in the shadow zone mainly mirrors dissipative states with presence or absence of bars; and （2） the sequential changes and differences of beach states in different coastal zones reflect spatial and temporal variabilities of the headland- bay coast, totally meeting the actual measured beach morphology changes, showing that studies on wave- dominated, meso-macrotidal beaches need to consider the influences of the tides. Meanwhile, the research mainly provides a framework about beach state studies, due to different beach states with different erosion patterns, which requires the need to strengthen the researches in this respect, in order to further enrich theoretical basis for a beach topography evolution, beach morphodynamic processes and beach erosion orevention in China.
基金Under the auspices of National Social Science Foundation of China(No.14BJY021)National Natural Science Foundation of China(40901296,U1404402)Youth backbone teachers of Henan province’s universities(No.2014GGJS-044)
文摘Understanding the spatial interactions among multiple ecosystem services is crucial for ecosystem services management. Ecosystem services, including crop production, freshwater supply, aquatic production, net primary production, soil conservation, water conservation, flood regulation, forest recreation, were measured at 1-km grid scale covering the Taihu Lake Basin(TLB) of China. Our objective is to get a comprehensive understanding of the spatial distributions, trade-offs, synergies of multiple ecosystem services across the TLB. Our results found that: 1) majority of ecosystem services were clustered in space and had a similar spatial distribution pattern with the geographical resource endowment. Most of the landscape contributed a high supply of no services, one or two, and a low supply of three to seven services. 2) There were high correlation between forest recreation and freshwater supply and regulating services. Aquatic production had low correlation with other services. 3) The changes of provisioning services led to trade-offs between regulating services and cultural services in the TLB, while synergies mainly occurred among the provisioning service. 4) The spatial relationships of multiple services are consistent at 1-km spatial scale, counties and provinces. This research could help integrate multiple ecosystem services across scales and serve as a reference for decision making.
基金supported by the Fund of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,China(10501-1201)the Key Technologies R&D Program of China during the 11th Five-Year Plan period(2012BAD14B08)the Innovation Team Program,Ministry of Education of China
文摘Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals （nHRS）, drought tolerance and water use efficiency of winter wheat （Triticum aestivum）. The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots （1.06 and 0.94 mmol g-1 s-1, respectively）. The soil water content （SWC） at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants （61.1-44.6% field water capacity） than for intact root plants （57.9-46.1% field water capacity）. At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield （F PS II ）, the maximum photochemical efficiency of PS II （F v /F m ）, coefficient of photochemical quenching （qP）, and coefficient of non-photochemical quenching （NPQ）, in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency （WUE） than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of drought- resistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.
基金funded by the National Natural Science Foundation of China (No.52104129)the Key Laboratory of Mine Ecological Effects and Systematic Restoration,the Ministry of Natural Resources (No.MEER-2022-09)+2 种基金the China Postdoctoral Science Foundation (No.2022T150195)the Shandong Provincial Major Science and Technology Innovation Project (No.2019SDZY05)the Doctoral Fund of Henan Polytechnic University (No.B2021-59)
文摘The development of industry is inseparable from the support of mining.However,mining processes consume a large amount of energy,and increased tailing emissions can have a significant impact on the environment.In the past few decades,the mining industry developed many technologies that are related to mineral energy management,of which cemented paste backfill(CPB)is one of the representative technologies.CPB has been successfully applied to mine ground control and tailings management.In CPB technology,the mixing process is the key to achieving materials with good final quality and controlled properties.However,in the preparation process,the mixed homogeneity of the CPB is difficult to achieve because of fine tailings,high solid volume fraction,and high viscosity.Most research focused on the effect of mixing ingredients on CPB properties rather than on the preparation process of the CPB.Therefore,improving the performance and reducing the production cost of CPB by optimizing the mixing process are important.This review summarizes the current studies on the mixing technology of CPB and its application status in China.Then,it compares the advantages and disadvantages of multiple mixing equipment and discusses the latest results and research hotspots in paste preparation.Finally,it concludes the challenges and development trends of mixing technology on the basis of the relevant application cases in China to promoting cement-based material mixing technology development.
基金Under the auspices of National Natural Science Foundation of China(No.41971274)the Innovation Research Team of Henan Provincial University(No.2021-CXTD-08,2022-CXTD-02)the Scientific and Technological Innovation Team of Universities in Henan Province(No.22IRTSTHN008)。
文摘The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China.Taking the Zhengzhou metropolitan area(ZZMA)as a case study,we developed an inverse S-shape model to characterize the spatial distribution of urban land density,and constructed an urban expansion core index,urban expansion intensity index,and urban compactness index to quantify the spatial structure change that has taken place from 1978 to 2017 during the process of urban expansion.Moreover,cropland contribution rate(CR)was constructed to evaluate the impacts of urban expansion on croplands.We uncovered four key findings.First,over the past 40 yr,the ZZMA has experienced dramatic expansion,and the central city of Zhengzhou expanded faster than other cities.The gravity centers of urban expansion of surrounding cities were moving toward to Zhengzhou City.Second,the urban land density decreased with the distance from the city center to the outskirts.As the only large city,Zhengzhou has experienced the fastest and most compact centralized urban expansion,especially after 2000,while other medium-and small-sized cities have experienced low-intensity decentralized expansion.Third,the urban core has been gradually expanding outward.From 1978 to 2017,the hot-zone of urban growth has moved progressively with the acceleration of urbanization.All cities except Jiaozuo had a single peak in different periods.Forth,the cities in national core grain-producing areas has higher cropland contribution rates and lower urban expansion areas,which was closely related to cropland protection.Further analysis showed that large city was relatively better positioned than smaller cities in the efficiency of their urban infrastructure and the effectiveness of wealth creation efficiency in the urbanized area could be tested in all cities,and the policy factor seemed to play an important role in the urban expansion process.
基金sponsored by the National Key Research&Development Program of China(2017YFB0504204)the K.C.Wong Education Foundation(GJTD-2020-14)+1 种基金the International Collaboration Project of the Chinese Academy of Sciences(131965KYSB20200029)the New Water Resources Strategic Research Project in Southern Xinjiang Uygur Autonomous Region,China(403-1005-YBN-FT6I-8)。
文摘Glaciers are highly sensitive to climate change and are undergoing significant changes in mid-latitudes.In this study,we analyzed the spatiotemporal changes of typical glaciers and their responses to climate change in the period of 1990-2015 in 4 different mountainous sub-regions in Xinjiang Uygur Autonomous Region of Northwest China:the Bogda Peak and Karlik Mountain sub-regions in the Tianshan Mountains;the Yinsugaiti Glacier sub-region in the Karakorum Mountains;and the Youyi Peak sub-region in the Altay Mountains.The standardized snow cover index(NDSI)and correlation analysis were used to reveal the glacier area changes in the 4 sub-regions from 1990 to 2015.Glacial areas in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions in the period of 1990-2015 decreased by 57.7,369.1,369.1,and 170.4 km^(2),respectively.Analysis of glacier area center of gravity showed that quadrant changes of glacier areas in the 4 sub-regions moved towards the origin.Glacier area on the south aspect of the Karlik Mountain sub-region was larger than that on the north aspect,while glacier areas on the north aspect of the other 3 sub-regions were larger than those on the south aspect.Increased precipitation in the Karlik Mountain sub-region inhibited the retreat of glaciers to a certain extent.However,glacier area changes in the Bogda Peak and Youyi Peak sub-regions were not sensitive to the increased precipitation.On a seasonal time scale,glacier area changes in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions were mainly caused by accumulated temperature in the wet season;on an annual time scale,the correlation coefficient between glacier area and annual average temperature was-0.72 and passed the significance test at P<0.05 level in the Karlik Mountain sub-region.The findings of this study can provide a scientific basis for water resources management in the arid and semi-arid regions of Northwest China in the context of global warming.
文摘Fully normalized associated Legendre functions(fnALFs)are a set of orthogonal basis functions that are usually calculated by using the recurrence equation.This paper presented the applicability and universality of the standard forward column/row recurrence equation based on the isolated singular factor method and extended-range arithmetic.Isolating a singular factor is a special normalization method that can improve the universality of the standard forward row recurrence equation to a certain extent,its universality can up to degree hundreds.However,it is invalid for standard forward column recurrence equation.The extended-range arithmetic expands the double-precision number field to the quad-precision numberfield.The quad-precision numberfield can retain more significant digits in the operation process and express larger and smaller numbers.The extended-range arithmetic can significantly improve the applicability and universality of the standard forward column/row recurrence equations,its universality can up to degree several thousand.However,the quad-precision numberfield operation needs to occupy more storage space,which is why its operation speed is slow and undesirable in practical applications.In this paper,the X-number method is introduced in the standard forward row recurrence equation for thefirst time.With the use of the X-number method,fnALFs can be recursed to 4.2 billion degree by using standard forward column/row recurrence equations.
基金This study was supported by the Natural Science Foundation of China(41871333)the Important Project of Science and Technology of the Henan Province(182102110186)Thanks go to Haikuan Feng for the image data and field sampling collection.
文摘The estimation of potato biomass and yield can optimize the planting pattern and tap the production potential.Based on partial least square(PLSR),multiple linear regression(MLR),support vector machine(SVM),random forest(RF),BP neural network and other machine learning algorithms,the biomass estimation model of potato in different growth stages is constructed by using single variables such as original spectrum,first-order differential spectrum,combined spectrum index and vegetation index(VI)and their coupled combination variables.The accuracy of the models is compared and analyzed,and the best modeling method of biomass in different growth stages is selected.Based on the optimized modeling method,the biomass of each growth stage is estimated,and the yield estimation model of different growth stages is constructed based on the estimation results and the linear regression analysis method,and the accuracy of the model is verified.The results showed that in tuber formation stage,starch accumulation stage and maturity stage,the biomass estimation accuracy based on combination variable was the highest,the best modeling method was MLR and SVM,in tuber growth stage,the best modeling method was MLR,the effect of yield estimation is good.It provides a reference for the algorithm selection of crop biomass and yield models based on machine learning.
基金funded by the Second Tibetan Plateau Scientific Explorationthe Strategic Priority Research Program of Chinese Academy of Sciences+1 种基金the National Natural Science Foundation,grant number 2019QZKK0404,XDA20020401,41977284by the Doctoral Science Foundation of Henan Polytechnic University(B2019-019)。
文摘The response of vegetation productivity to precipitation is becoming a worldwide concern.Most reports on responses of vegetation to precipitation trends are based on the growth season.In the soil freeze/thaw process,the soil water phase and heat transport change can affect root growth,especially during the thawing process in early spring.A field experiment with increased precipitation(control,increased 25%and increased 50%)was conducted to measure the effects of soil water in early spring on above-and below-ground productivity in an alpine steppe over two growing seasons from June 2017 to September 2018.The increased 50%treatment significantly increased the soil moisture at the 10 cm depth,there was no difference in soil moisture between the increased 25%treatment and the control in the growing season,which was not consistent in the freeze/thaw process.Increased soil moisture during the non-growing season retarded root growth.Increased precipitation in the freezing-thawing period can partially offset the difference between the control and increased precipitation plots in both above-and below-ground biomass.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.42471424,41975036,and 42075132)the Fengyun Application Pioneering Project(Grant No.FY-APP024)+1 种基金the State Key Project of National Natural Science Foundation of China-Key projects of joint fund for regional innovation and development(Grant No.U22A20566)the Scientific and Technological Innovation Team of Universities in Henan Province(Grant No.22IRTSTHN008).
文摘The Medium-Resolution Spectral Imager-Ⅱ(MERSI-Ⅱ)instrument aboard China’s Fengyun-3D satellite shares similarities with NASA’s Moderate Resolution Imaging Spectroradiometer(MODIS)sensor,enabling the retrieval of global aerosol optical depth(AOD).However,no officially released operational MERSI-Ⅱ aerosol products currently exist over the ocean.This study focuses on adapting the MODIS dark target(DT)ocean algorithm to the MERSI-Ⅱ sensor.A retrieval test is conducted on the 2019 MERSI-Ⅱ data over the global ocean,and the retrieved AODs are validated against ground-based measurements from the automatic Aerosol Robotic Network(AERONET)and the shipborne Maritime Aerosol Network(MAN).The operational MODIS DT aerosol products are also used for comparison purposes.The results show that MERSI-Ⅱ AOD granule retrievals are in good agreement with MODIS products,boasting high correlation coefficients(R)of up to 0.96 and consistent spatial distribution trends.Furthermore,the MERSI-Ⅱ retrievals perform well in comparison to AERONET and MAN measurements,with high R-values(>0.86).However,the low-value retrievals from MERSI-Ⅱ tend to be slightly overestimated compared to MODIS,despite both AODs displaying a positive bias.Notably,the monthly gridded AODs over the high latitudes of the northern and southern hemispheres suggest that MERSI-Ⅱ exhibits greater stability in space and time,effectively reducing unrealistically high-value noise in the MODIS products.These results illustrate that the MERSI-Ⅱ retrievals meet specific accuracy requirements by maintaining the algorithmic framework and most of the algorithmic assumptions,providing a crucial data supplement for aerosol studies and climate change.
基金Project funded by the National Nature Fund(41371498,42071007)。
文摘The comparison results of three beach profile data repeatedly measured before and after the typhoon in Shuidong Bay,west Guangdong province which show that there are significant differences in beach profile erosion and response process.And the changes of beach profile can be divided into:strong downward overall low shoreline regressive type and overall slight erosion shoreline regressive type.Application of the modified mildslope equation along three beach profile are simulated wave high reflection to the sea side,to the section vertical shore pressure gradient and including water roll force and radiation stress,the vertical shore forces one dimensional profile along the momentum conservation equation(radiation stress and water roll force)bottom friction and lateral mixing reaction between numerical solution,the momentum conservation equations of the wave increases the water flow velocity and section along the profile distribution of wave height and related forces.The analysis shows that the extent and difference of coastal erosion depend on the shoreline erosion mode stimulated by the maximum surge water of the coastal current and the maximum velocity of the coastal current and the dynamic state of the profile topography under the action of the profile location,morphology and incident wave elements.
基金supported by the National Natural Science Foundation of China(42101382 and 41901342)the Shandong Provincial Natural Science Foundation(ZR2020QD016)the National Key Research and Development Program of China(2016YFD0300101).
文摘Accurate estimation of regional winter wheat yields is essential for understanding the food production status and ensuring national food security.However,using the existing remote sensing-based crop yield models to accurately reproduce the inter-annual and spatial variations in winter wheat yields remains challenging due to the limited ability to acquire irrigation information in water-limited regions.Thus,we proposed a new approach to approximating irrigations of winter wheat over the North China Plain(NCP),where irrigation occurs extensively during the winter wheat growing season.This approach used irrigation pattern parameters(IPPs)to define the irrigation frequency and timing.Then,they were incorporated into a newly-developed process-based and remote sensing-driven crop yield model for winter wheat(PRYM–Wheat),to improve the regional estimates of winter wheat over the NCP.The IPPs were determined using statistical yield data of reference years(2010–2015)over the NCP.Our findings showed that PRYM–Wheat with the optimal IPPs could improve the regional estimate of winter wheat yield,with an increase and decrease in the correlation coefficient(R)and root mean square error(RMSE)of 0.15(about 37%)and 0.90 t ha–1(about 41%),respectively.The data in validation years(2001–2009 and 2016–2019)were used to validate PRYM–Wheat.In addition,our findings also showed R(RMSE)of 0.80(0.62 t ha–1)on a site level,0.61(0.91 t ha–1)for Hebei Province on a county level,0.73(0.97 t ha–1)for Henan Province on a county level,and 0.55(0.75 t ha–1)for Shandong Province on a city level.Overall,PRYM–Wheat can offer a stable and robust approach to estimating regional winter wheat yield across multiple years,providing a scientific basis for ensuring regional food security.
基金supported by the National Key Research and Development Program of China[grant numbers 2022YFF0711603,2019YFA0607101]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA23100102]+1 种基金Science and Technology Planning Project of NIGLAS[grant numbers 2022NIGLAS-CJH04,2022NIGLAS-TJ18]the National Natural Science Foundation of China[grant numbers 41971403,41930102,42171421 and 41975036].
文摘Synthesis of multi-satellite altimetry facilitates the acquisition of long-term changes in lake level but may induce biases due to inconsistent data sources,and thus remains largely unexplored.This study investigates the integrated application of Ice,Cloud,and land Elevation Satellite(ICESat),ICESat-2,and CryoSat-2 missions to provide consecutive lake level series in 2003–2020.The sample comprises 48 lakes in the world with gauge-based or Hydroweb water level data.The CryoSat-2 data arefirst adjusted to the ICESat-2 height reference based on the mean values of their monthly water level difference during their overlapping period(2018–2020).Then,the corrected CryoSat-2 data are used to link the ICESat and ICESat-2 data.Results show that in the sample lakes,the deviations between CryoSat-2 and ICESat-2 data vary and range from-0.78 m to 0.13 m.The data quality of the synthesized time series is evaluated by comparing against the validation data,with an average R^(2) of 0.84.This study shows that CryoSat-2 has the potential offilling the gap between ICESat and ICESat-2.The three altimeters can be expected to integrate effectively for monitoring lake water level changes in the past two decades.
基金funded by the Science and Disruptive Technology Program, AIRCAS(Grant No. 2024-AIRCAS-SDPT- 15)the National Natural Science Foundation of China (Grant No. 42471372).
文摘Soybean is one of the most important oil crops, and Argentina is the third-largest soybean producer in the world, accounting for 17% of the global soybean yield. Timely and accurate information on soybean spatial distribution is critical for ensuring global food security. Sentinel-2 multispectral data and machine learning classification models are used to investigate the potential of soybean identification in the early stage of the growing season in Argentina, with the help of Google Earth Engine (GEE). The earliest time window and optimal feature set for soybean identification are explored. Results are as follows: 1) the random forest (RF) classification model demonstrated the highest level of classification accuracy compared to the backpropagation neural network (BPNN), support vector machine (SVM), and naive Bayes (NB) models;2) Soybean can be accurately identified as early as the end of February (filling stage), which is approximately one month before harvest;3) The optimal feature-subset can reduce the amount of input data by 80% while maintaining high classification accuracy. The overall accuracy (OA) of the RF classification model is 85.87%, and the relative error between the estimated soybean planting area and the agricultural statistics is 3.45%. This study provided a high-precision method for early-season identification of soybeans over large scales. The results can provide a data support for early futures trading and agricultural insurance, as well as a reference for policy-making to ensure global soybean food security.
