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Development of a daily soil moisture product for the period of 2002–2011 in Mainland China

science China Earth sciences 2020年

作者： Kun YANG Yingying CHEN Jie HE Long ZHAO Hui LU Jun QIN Donghai ZHENG Xin LI Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences National Tibetan Plateau Data Center Institute of Tibetan Plateau Research Chinese Academy of Sciences School of Geographical Sciences Southwest University

Soil moisture is an essential climate variable（ECV） concerned widely. Due to its high spatial variability, it is costly to measure soil moisture at tens of kilometers scale. In this study, a ten-year（2002–2011） daily soil moisture dataset at 0.25° spatial resolution for Mainland China was produced through assimilating the Advanced Microwave Scanning Radiometer for Earth Observing System（AMSR-E） brightness temperature（TB） data into a land surface model（LSM）. The obtained soil moisture data was evaluated against soil moisture-measuring networks deployed in two wet areas and one dry area of the Tibetan *** results show that for the wet areas the accuracy of the soil moisture product obtained from the assimilation is considerably higher than that of both AMSR-E official soil moisture products and land surface simulation results, and for the dry area their accuracy is comparable to each other. The spatial pattern of the soil moisture from the new product is consistent with that of soil porosity from an independent survey-based dataset, further confirming the credibility of the new product. According to this product, the transition regions in China show stronger seasonal variation of soil moisture than dry and wet regions, and drier regions have stronger inter-annual variability of soil moisture than wetter regions, particularly during transitional seasons（spring and autumn）. The soil moisture product is accessible at the National Tibetan Plateau data Center.

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RANDOMIZATION for the EFFICIENT COMPUTATION of PARAMETRIC REDUCED ORDER MODELS for INVERSION

arXiv

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arXiv 2020年

作者： Aslan, Selin de Sturler, Eric Gugercin, Serkan Advanced Photon Source Argonne National Laboratory LemontIL60439 United States Department of Mathematics and Computational Modeling and Data Analytics Division Academy of Integrated Science Virginia Tech BlacksburgVA24061 United States Department of Mathematics and Computational Modeling and Data Analytics Division Academy of Integrated Science Virginia Tech BlacksburgVA2406 United States

Nonlinear parametric inverse problems appear in many applications. In this work, we focus on diffuse optical tomography (DOT) in medical image reconstruction, in which we aim to recover an unknown image of interest (defined by a set of parameters), such as cancerous tissue in a given medium, using a mathematical (forward) model. The forward model in DOT is a diffusion-absorption model for the photon flux. The main computational bottleneck in such inverse problems is the repeated evaluation of the large-scale forward model. For DOT, this corresponds to solving large linear systems for each source and frequency at each optimization step. In addition, as Newton-type methods are the method of choice for these problems, one needs to solve additional linear systems with the adjoint to efficiently compute derivative information. As rapid advances in technology allow for large numbers of sources and detectors, these problems become computationally prohibitively expensive. In the past, the use of reduced order models (ROM) has been proposed to drastically reduce the size of the linear systems solved in each optimization step, while still solving the inverse problem accurately. However, as the number of sources and detectors increases, even the construction of the ROM bases incurs a substantial cost. Interpolatory model reduction, when performed in the setting of full matrix-interpolation to match the full parameter gradient matrix, requires the solution of large linear systems for all sources and frequencies as well as for all detectors and frequencies for each interpolation point in parameter space to build a candidate basis for the ROM projection space. As this candidate basis numerically has low rank, this construction is followed by a rank-revealing factorization that typically reduces the number of vectors in the candidate basis substantially. Since only the ROM projection space matters, not its basis, we propose to use randomization to approximate this basis efficientl

关键词： Inverse problems

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Mass conservative reaction diffusion systems describing cell polarity

arXiv

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arXiv 2020年

作者： Latos, Evangelos Suzuki, Takashi Institut für Mathematik und Wissenschaftliches Rechnen Heinrichstraße 36 Graz8010 Austria Center for Mathematical Modeling and Data Science Osaka University

A reaction-diffusion system with mass conservation modelling cell polarity is considered. A range of the parameters is found where the solution converges exponentially to the constant equilibrium and the ω-limit set of the solution is spatially homogeneous, containing the constant stationary solution as well as possible spatially homogeneous orbits. Copyright © 2020, The Authors. All rights reserved.

关键词： Dynamic models

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Space-time upscaling of reactive transport in porous media

arXiv

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arXiv 2021年

作者： Suciu, Nicolae Radu, Florin A. Pop, Iuliu S. Tiberiu Popoviciu Institute of Numerical Analysis Romanian Academy Fantanele 57 Cluj-Napoca400320 Romania Center for Modeling of Coupled Subsurface Dynamics University of Bergen Allégaten 41 Bergen5007 Norway Data Science Institute Hasselt University Campus Diepenbeek Diepenbeek3590 Belgium

Reactive transport in saturated/unsaturated porous media is numerically upscaled to the space-time scale of a hypothetical measurement through coarse-grained space-time (CGST) averages. The reactive transport is modeled at the fine-grained Darcy scale by the actual number of molecules involved in reactions which undergo advective and diffusive movements described by global random walk (GRW) simulations. The CGST averages verify identities similar to a local balance equation which allow us to derive expressions for the flow velocity and the intrinsic diffusion coefficient in terms of averaged microscopic quantities. The latter are further used to verify the CGST-GRW numerical approach. The upscaling approach is applied to biodegradation processes in saturated aquifers and variably saturated soils and the CGST averages are compared to classical volume averages. One finds that if the process is characterized by slow variations in time, as in homogeneous reaction systems, the differences between the two averages are negligible. Instead, the differences are significant and can be extremely large in simulations of time-dependent biodegradation processes in both soils and saturated *** Codes 76S05 (Primary) 35K57, 86A05, 65C35 (Secondary) © 2021, CC BY-NC-ND.

关键词： Aquifers

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EDGE DIFFERENTIALLY PRIVATE ESTIMATION IN THE β-MODEL VIA JITTERING AND METHOD OF MOMENTS

arXiv

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arXiv 2021年

作者： Chang, Jinyuan Hu, Qiao Kolaczyk, Eric D. Yao, Qiwei Yi, Fengting Joint Laboratory of Data Science and Business Intelligence Southwestern University of Finance and Economics Chengdu611130 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Department of Mathematics and Statistics McGill University MontrealQCH3A 0B8 Canada Department of Statistics London School of Economics and Political Science LondonWC2A 2AE United Kingdom Yunnan Key Laboratory of Statistical Modeling and Data Analysis Yunnan University Kunming650500 China

A standing challenge in data privacy is the trade-off between the level of privacy and the efficiency of statistical inference. Here we conduct an in-depth study of this trade-off for parameter estimation in the β-model (Chatterjee, Diaconis and Sly, 2011) for edge differentially private network data released via jittering (Karwa, Krivitsky and Slavković, 2017). Unlike most previous approaches based on maximum likelihood estimation for this network model, we proceed via method-of-moments. This choice facilitates our exploration of a substantially broader range of privacy levels – corresponding to stricter privacy – than has been to date. Over this new range we discover our proposed estimator for the parameters exhibits an interesting phase transition, with both its convergence rate and asymptotic variance following one of three different regimes of behavior depending on the level of privacy. Because identification of the operable regime is difficult if not impossible in practice, we devise a novel adaptive bootstrap procedure to construct uniform inference across different phases. In fact, leveraging this bootstrap we are able to provide for simultaneous inference of all parameters in the β-model (i.e., equal to the number of nodes), which, to our best knowledge, is the first result of its kind. Numerical experiments confirm the competitive and reliable finite sample performance of the proposed inference methods, next to a comparable maximum likelihood method, as well as significant advantages in terms of computational speed and memory. Copyright © 2021, The Authors. All rights reserved.

关键词： Method of moments

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Record High Temperatures in the Ocean in 2024

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Advances in Atmospheric sciences 2025年第6期42卷 1092-1109页

作者： Lijing CHENG John ABRAHAM Kevin E.TRENBERTH James REAGAN Huai-Min ZHANG Andrea STORTO Karina VON SCHUCKMANN Yuying PAN Yujing ZHU Michael E.MANN Jiang ZHU Fan WANG Fujiang YU Ricardo LOCARNINI John FASULLO Boyin HUANG Garrett GRAHAM Xungang YIN Viktor GOURETSKI Fei ZHENG Yuanlong LI Bin ZHANG Liying WAN Xingrong CHEN Dakui WANG Licheng FENG Xiangzhou SONG Yulong LIU Franco RESEGHETTI Simona SIMONCELLI Gengxin CHEN Rongwang ZHANG Alexey MISHONOV Zhetao TAN Wangxu WEI Huifeng YUAN Guancheng LI Qiuping REN Lijuan CAO Yayang LU Juan DU Kewei LYU Albertus SULAIMAN Michael MAYER Huizan WANG Zhanhong MA Senliang BAO Henqian YAN Zenghong LIU Chunxue YANG Xu LIU Zeke HAUSFATHER Tanguy SZEKELY Flora GUES National Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of St.Thomas School of EngineeringMinnesota 55105USA NSF National Center for Atmospheric Research BoulderColorado 80307USA University of Auckland Auckland 0630New Zealand National Oceanic and Atmospheric Administration National Centers for Environmental InformationSilver SpringMaryland 20910USA National Oceanic and Atmospheric Administration National Centers for Environmental InformationAshevilleNC 28801USA National Research Council(CNR)Institute of Marine Sciences(ISMAR) Rome 00133Italy Mercator Ocean International Toulouse 31400France Department of Earth and Environmental Science University of PennsylvaniaPhiladelphiaPennsylvania 19104USA Institute of Oceanology Chinese Academy of SciencesQingdao 266071China National Marine Environmental Forecasting Center Ministry of Natural Resources of ChinaBeijing 100081China North Carolina Institute for Climate Studies(NCICS) North Carolina State UniversityAshevilleNC 28804USA Oceanographic Data Center Chinese Academy of SciencesQingdao 266071China College of Oceanography Hohai UniversityNanjing 210098China National Marine Data and Information Service Tianjin 300171China Istituto Nazionale di Geofisica e Vulcanologia Sede di BolognaBologna 40128Italy South China Sea Institute of Oceanology Chinese Academy of SciencesGuangzhou 510301China ESSIC/CISESS-MD University of MarylandCollege ParkMD 20740USA Computer Network Information Center Chinese Academy of SciencesBeijing 100083China Eco-Environmental Monitoring and Research Center Pearl River Valley and South China Sea Ecology and Environment AdministrationMinistry of Ecology and EnvironmentGuangzhou 510611China National Meteorological Information Center China Meteorological AdministrationBeijing 100081China International Research Center of Big Data for Sustainable Development Goals Beijing 100094China Xiamen Universit

Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temperature(SST) and upper2000 m ocean heat content(OHC) reached unprecedented highs in the historical record. The 0–2000 m OHC in 2024exceeded that of 2023 by 16 ± 8 ZJ(1 Zetta Joules = 1021 Joules, with a 95% confidence interval)(IAP/CAS data), which is confirmed by two other data products: 18 ± 7 ZJ(CIGAR-RT reanalysis data) and 40 ± 31 ZJ(Copernicus Marine data,updated to November 2024). The Indian Ocean, tropical Atlantic, Mediterranean Sea, North Atlantic, North Pacific, and Southern Ocean also experienced record-high OHC values in 2024. The global SST continued its record-high values from2023 into the first half of 2024, and declined slightly in the second half of 2024, resulting in an annual mean of 0.61°C ±0.02°C(IAP/CAS data) above the 1981–2010 baseline, slightly higher than the 2023 annual-mean value(by 0.07°C ±0.02°C for IAP/CAS, 0.05°C ± 0.02°C for NOAA/NCEI, and 0.06°C ± 0.11°C for Copernicus Marine). The record-high values of 2024 SST and OHC continue to indicate unabated trends of global heating.

关键词： ocean heat content sea surface temperature ocean temperature global warming climate

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On the balanced truncation error bound and sign parameters from arrowhead realizations

arXiv

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arXiv 2020年

作者： Reiter, Sean Damm, Tobias Embree, Mark Gugercin, Serkan Department of Mathematics Virginia Tech BlacksburgVA24061 United States Kaiserslautern67653 Germany Department of Mathematics Division of Computational Modeling and Data Analytics Academy of Data Science Virginia Tech BlacksburgVA24061 United States

Balanced truncation and singular perturbation approximation for linear dynamical systems yield reduced-order models that satisfy a well-known error bound involving the Hankel singular values. We show that this bound holds with equality for single-input, single-output systems, if the sign parameters corresponding to the truncated Hankel singular values are all equal. These signs are determined by a generalized state-space symmetry property of the corresponding linear model. For a special class of systems having arrowhead realizations, the signs can be determined directly from the off-diagonal entries of the corresponding arrowhead matrix. We describe how such arrowhead systems arise naturally in certain applications of network modeling, and illustrate these results with a power system model that motivated this *** Codes 93B10, 93B11, 93C05 Copyright © 2020, The Authors. All rights reserved.

关键词： Dynamical systems

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Series expansion of weighted Finsler-Kato-Hardy inequalities

arXiv

引用

arXiv 2019年

作者： Tzirakis, Konstantinos Center for Mathematcal Modeling and Data Science Osaka University Japan

In this work we consider weighted anisotropic Hardy inequalities and trace Hardy inequalities involving a general Finsler metric. We follow a unifying approach, by establishing first a sharp interpolation between them, extending the corresponding nonweighted version, being established recently by a different approach. Then, passing to bounded domains, we obtain successive sharp improvements by adding remainder terms involving sharp weights and optimal constants, resulting in an infinite series-type improvement. The results extend, into the Finsler context, the earlier known ones within the Euclidean setting. The generalization of our results to cones is also *** Codes 35J20 (Primary) 26D10, 46E35 (Secondary) Copyright © 2019, The Authors. All rights reserved.

关键词： Anisotropy

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Assessing the impact of climate change on habitat shifts of typical endemic relict trees in China

引用

Global Ecology and Conservation 2025年 61卷

作者： Li, Ming Wang, Junbang Zhang, Xiujuan Yang, Yongsheng College of Horticulture and Gardening Yangtze University Jingzhou 434025 China National Ecosystem Science Data Center Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Key Laboratory of Adaptation and Evolution of Plateau Biota Northwest Institute of Plateau Biology Chinese Academy of Science Xining 810008 China

Extensive evidence supports that global climate change influences shifts in species habitats due to alterations in hydrothermal conditions;however, neglecting dispersal capacities and limits significantly heightens uncertainties regarding spatial distribution patterns among different organisms. This study presents novel insights into how climate change, land use practices, and ecological interactions drive changes in habitats occupied by Chinese Endemic Relict Trees (CERT) (Pseudotaxus chienii, Pseudolarix amabilis, Metasequoia glyptostroboides, Glyptostrobus pensilis, Ginkgo biloba, and Cathaya argyrophylla), using current (2000–2020) occurrence data and specific environmental variables for each individual tree. The optimized MaxEnt and MigClim models enabled us to forecast potential colonizable habitats under the paleoclimatic condition and future two emission scenarios (SSP126 and SSP585), assess alterations across the aggregation area of six trees over periods, and identify focal points for future efforts aimed at conserving biocultural diversity. Our findings showed that: (1) Temperature-precipitation-related factors predominantly drove expansion or contraction trends within habitats occupied by CERT, and land use has occupied many more habitats;although prospects appear promising under the SSP126 scenario, it also entailed substantial losses of G. pensilis. (2) Habitat decline and fragmentation are particularly pronounced in the two provinces, Hunan and Jiangxi, with limited spread observed in Yunnan Province. The diminishing range of M. glyptostroboides and G. pensilis notable in northern Guangdong as well as northeastern Guangxi Province. (3). By the end of this century, the southeast coast and central China are expected to experience greater long-term stability. In conclusion, this research minimizes uncertainties associated with projecting species distributions within changing climates while offering theoretical backing for safeguarding biocultural diversi

关键词： Chinese endemic relict tree Climate change Dispersal potential and limited Potential colonizable habitats

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Correction: A scale-adaptive estimation for mixed geographically and temporally weighted regression models

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Journal of Geographical Systems 2025年第2期27卷 337-337页

作者： Hong, Zhimin Wang, Zhiwen Wang, Huhu Wang, Ruoxuan Department of Mathematics School of Science Inner Mongolia University of Technology Hohhot China Statistics Inner Mongolia Key Laboratory of Statistical Analysis Theory for Life Data and Neural Network Modeling Hohhot China Institute for Infectious Disease and Endemic Disease Control Inner Mongolia Autonomous Region Center for Disease Control and Prevention Hohhot China

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