检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Silverman, Sam M. Hayakawa, Hisashi 18 Ingleside Road LexingtonMA United States Institute for Space-Earth Environmental Research Nagoya University Nagoya4648601 Japan Institute for Advanced Researches Nagoya University Nagoya4648601 Japan UK Solar System Data Centre Space Physics and Operations Division RAL Space Science and Technology Facilities Council Rutherford Appleton Laboratory Harwell Oxford Didcot Oxfordshire OX11 0QX United Kingdom

In addition to the regular Schwabe cycles of approximately 11 y, "prolonged solar activity minima" have been identified through the direct observation of sunspots and aurorae, as well as proxy data of cosmogenic isotopes. Some of these minima have been regarded as grand solar minima, which are arguably associated with the special state of the solar dynamo and have attracted significant scientific interest. In this paper, we review how these prolonged solar activity minima have been identified. In particular, we focus on the Dalton Minimum, which is named after John Dalton. We review Dalton’s scientific achievements, particularly in geophysics. Special emphasis is placed on his lifelong observations of auroral displays over approximately five decades in Great Britain. Dalton’s observations for the auroral frequency allowed him to notice the scarcity of auroral displays in the early 19th century. We analyze temporal variations in the annual frequency of such displays from a modern perspective. The contemporary geomagnetic positions of Dalton’s observational site make his dataset extremely valuable because his site is located in the sub-auroral zone and is relatively sensitive to minor enhancements in solar eruptions and solar wind streams. His data indicate clear solar cycles in the early 19th century and their significant depression from 1798 to 1824. Additionally, his data reveal a significant spike in auroral frequency in 1797, which chronologically coincides with the "lost cycle" that is believed to have occurred at the end of Solar Cycle 4. Therefore, John Dalton’s achievements can still benefit modern science and help us improve our understanding of the Dalton Minimum. Copyright © 2020, The Authors. All rights reserved.

关键词： Solar energy

来源：评论

学校读者我要写书评

暂无评论

Implications of shallow-shell models for topographic relaxation on icy satellites

arXiv

引用

arXiv 2025年

作者： Meyer, Colin R. Stubblefield, Aaron G. Minchew, Brent M. Pegler, Samuel S. Berne, Alexander Buffo, Jacob J. Tomlinson, Tara C. Thayer School of Engineering Dartmouth College HanoverNH03755 United States Earth System Science Interdisciplinary Center University of Maryland College ParkMD20740 United States Global Modeling and Assimilation Office NASA Goddard Space Flight Center GreenbeltMD20771 United States Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02142 United States School of Mathematics University of Leeds LS2 9JT United Kingdom Seismological Laboratory California Institute of Technology PasadenaCA91125 United States

Icy satellites host topography at many length scales, from rifts and craters on the small end to equatorial-pole shell thickness differences that are comparable to these bodies’ circumference. The rate of topographic evolution depends on the rheology of the ice shell, the difference in density between the shell and potential global subsurface oceans, the ice shell thickness distribution, as well as the rate of tidal heat dissipation in the shell. The current paradigm is that icy satellites should not host stable small-scale topography. This idea comes from previous work using a "shallow"-shell model (i.e. ice shell circumference is much larger than shell thickness) with a rigid outer crust. In this limit, large-scale topography relaxes over a longer time scale than small-scale features. Here we revisit this paradigm and analyze relaxation of topography starting from the Stokes equations for viscous fluid flow. We write out the shallow-shell models (with and without a rigid crust) and compare the resulting time scales to previous work. Using three-dimensional linearized flow for small-amplitude topographic perturbations, we recover the time scales of relaxation from the shallow models as well as shells that are not shallow. For a shell of constant viscosity, we find that the topographic relaxation time scale is constant for wavelengths larger than the ice thickness, an idea that runs contrary to the existing paradigm. For a shell with a viscosity that decreases exponentially with depth, we show numerically that there is a regime where the larger viscosity outer crust acts as a nearly rigid boundary. In this case, the relaxation time scale depends on the wavelength. For the largest spatial scales, however, the time scale becomes independent of wavelength again and the value is set by the average shell viscosity. However, the spatial scale that this transition occurs at becomes larger as the viscosity contrast increases, limiting the applicability of the scale-independ

关键词： Time measurement

来源：评论

学校读者我要写书评

暂无评论

Persistence of flare driven atmospheric chemistry on rocky habitable zone worlds

arXiv

引用

arXiv 2021年

作者： Chen, Howard Zhan, Zhuchang Youngblood, Allison Wolf, Eric T. Feinstein, Adina D. Horton, Daniel E. EvanstonIL60202 United States Department of Earth and Planetary Sciences Northwestern University EvanstonIL60202 United States Department of Earth Atmospheric Planetary Sciences Massachusetts Institute of Technology CambridgeMA02138 United States Laboratory for Atmospheric and Space Physics University of Colorado Boulder BoulderCO80309 United States NASA Nexus for Exoplanet System Science Virtual Planetary Laboratory SeattleWA98194 United States NASA Goddard Sellers Exoplanet Environments Collaboration GreenbeltMD United States Department of Astronomy & Astrophysics University of Chicago ChicagoIL60637 United States

Low-mass stars show evidence of vigorous magnetic activity in the form of large flares and coronal mass ejections. Such space weather events may have important ramifications for the habitability and observational fingerprints of exoplanetary atmospheres. Here, using a suite of three-dimensional coupled chemistry-climate model (CCM) simulations, we explore effects of time-dependent stellar activity on rocky planet atmospheres orbiting G-, K-, and M-dwarf stars. We employ observed data from the MUSCLES campaign and Transiting Exoplanet Satellite Survey and test a range of rotation period, magnetic field strength, and flare frequency assumptions. We find that recurring flares drive K- and M-dwarf planet atmospheres into chemical equilibria that substantially deviate from their pre-flare regimes, whereas G-dwarf planet atmospheres quickly return to their baseline states. Interestingly, simulated O2-poor and O2-rich atmospheres experiencing flares produce similar mesospheric nitric oxide abundances, suggesting that stellar flares can highlight otherwise undetectable chemical species. Applying a radiative transfer model to our CCM results, we find that flare-driven transmission features of bio-indicating species, such as nitrogen dioxide, nitrous oxide, and nitric acid, show particular promise for detection by future instruments. Copyright © 2021, The Authors. All rights reserved.

关键词： Nitrogen oxides

来源：评论

学校读者我要写书评

暂无评论

Large-scale absolute distance measurement with dual free-running all-polarization-maintaining femtosecond fiber lasers

引用

Chinese Optics Letters 2019年第9期17卷 55-59页

作者： Yuepeng Li Yawen Cai Runmin Li Haosen Shi Haochen Tian Mingzhao He Youjian Song Minglie Hu Ultrafast Laser Laboratory Key Laboratory of Opto-electronic Informa tion Science and Technology of Ministry of EducationSchool of Precision Instruments and Opto-electronics EngineeringTianjin UniversityTianjin 300072China Institute of Spacecraft System Engineering China Academy of Space TechnologyBeijing 100094China 'National Institute of MetrologyBeijing 100029China National Institute of Metrology Beijing 100029China

We demonstrate a robust femtosecond LIDAR setup by using two free-running environmentally stable allpolarization-maintaining nonlinear amplified loop mirror mode-locked fiber lasers. Based on the asynchronous optical sampling method, a ranging accuracy of ±2 μm within 65 m has been achieved, as tested in an 80-m-long underground optical tunnel. Through the Kalman filter in real-time data processing, the measurement accuracy can be maintained at a 200 Hz update rate. This setup provides a practical tool for various large-scale industrial and astronomical ranging applications.

关键词： distance measurement all-polarization-maintaining femtosecond fiber lasers

来源：评论

学校读者我要写书评

暂无评论

Understanding discrepancies in soil moisture from SMAP and AMSR2: insights into performance and dry-down behavior

引用

Mapping sciences and Remote Sensing 2025年第1期62卷

作者： Zhiqing Peng Tianjie Zhao Jiancheng Shi Lu Hu Thomas J. Jackson Michael H. Cosh Hui Lu Xiaodong Gao Jingyao Zheng Panpan Yao Qian Cui Peng Guo Peilin Song Zushuai Wei Mengjia Wang Anmin Fu a Key Laboratory of Remote Sensing and Digital Earth Aerospace Information Research Institute Chinese Academy of Sciences Beijing Chinab Department of Earth System Science Institute for Global Change Studies Tsinghua University Beijing China a Key Laboratory of Remote Sensing and Digital Earth Aerospace Information Research Institute Chinese Academy of Sciences Beijing China c National Space Science Center Chinese Academy of Sciences Beijing China d International Institute for Earth System Science Nanjing University Nanjing China e United States Department of Agriculture Agricultural Research Service Hydrology and Remote Sensing Laboratory (Retired) Beltsville MD USA f United States Department of Agriculture Agricultural Research Service Hydrology and Remote Sensing Laboratory Beltsville MD USA b Department of Earth System Science Institute for Global Change Studies Tsinghua University Beijing Chinag State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing Chinah Department of Earth System Science Tsinghua University- Xi’an Institute of Surveying and Mapping Joint Research Center for Next-Generation Smart Mapping Beijing China i Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling China j College of Surveying and Geo-Informatics North China University of Water Resources and Electric Power Zhengzhou China k Information Center (Hydrology Monitor and Forecast Center) Ministry of Water Resources Beijing China l College of Information Science and Engineering Shandong Agricultural University Taian China m Key Laboratory of Physical Electronics and Devices Ministry of Education Faculty of Electronic and Information Engineering Xi’an Jiaotong University Xi’an Shaanxi China n School of Artificial Intelligence Jianghan University Wuhan China o School of Geoscience and Technology Zhengzhou University Zhengzhou China p Academy of Forest Inventory and Planning National Forestry and Gr

ABSTRACTUnderstanding the dynamic changes in soil moisture (SM) is crucial for studying land–atmosphere interactions in hydrometeorology. While numerous SM datasets have been developed for passive microwave remote sensing systems operating at various frequencies, the consistency of SM dry-down patterns observed by different sensors remains uncertain. Additionally, the use of distinct algorithms across SM products complicates direct comparisons. This study addresses these issues by producing two new enhanced-resolution (approximately 10-km) SM datasets using the same multi-channel collaborative algorithm (MCCA). These datasets are retrieved from the L-band brightness temperature (Tb) from Soil Moisture Active Passive (SMAP) and the C/X/Ku-band Tb from Advanced Microwave Scanning Radiometer 2 (AMSR2), referred to as MCCA SMAP and MCCA AMSR2. The satellite-derived SM data are evaluated and compared using 40 globally distributed SM observation networks at both regional (dense network) and grid scales. The results indicate that the Pearson correlation coefficients (R) of MCCA SMAP and MCCA AMSR2 SM in 23 dense networks are 0.795 and 0.664, respectively, with unbiased root-mean-square deviation (ubRMSD) of 0.041 m3/m3and 0.048 m3/m3, respectively. Both datasets perform better at the regional scale than at the grid scale. The analysis shows that SMAP outperforms AMSR2 overall, although the sensing capabilities of both payloads decline with increasing vegetation water content (VWC). Further analysis of global SM dry-down patterns reveals minimal differences in the magnitude of SM dry-down between the two payloads, but slightly larger differences in the effective wilting point. A notable disparity was observed in SM memory, with SMAP exhibiting a significantly longer memory than AMSR2. Analysis of SM loss rates shows that SMAP has a lower loss rate compared to AMSR2, consistent with the theoretical expectation that lower-frequency observations, such as those from SMAP, obser

关键词： MCCA SMAP AMSR2 soil moisture dry-down

来源：评论

学校读者我要写书评

暂无评论

Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

arXiv

引用

arXiv 2023年

作者： Telloni, Daniele Zank, Gary P. Adhikari, Laxman Zhao, Lingling Susino, Roberto Antonucci, Ester Fineschi, Silvano Stangalini, Marco Grimani, Catia Sorriso-Valvo, Luca Verscharen, Daniel Marino, Raffaele Giordano, Silvio D'Amicis, Raffaella Perrone, Denise Carbone, Francesco Liberatore, Alessandro Bruno, Roberto Zimbardo, Gaetano Romoli, Marco Andretta, Vincenzo Da Deppo, Vania Heinzel, Petr Moses, John D. Naletto, Giampiero Nicolini, Gianalfredo Spadaro, Daniele Teriaca, Luca Burtovoi, Aleksandr De Leo, Yara Jerse, Giovanna Landini, Federico Pancrazzi, Maurizio Sasso, Clementina Slemer, Alessandra National Institute for Astrophysics Astrophysical Observatory of Torino Via Osservatorio 20 Pino TorineseI-10025 Italy Center for Space Plasma and Aeronomic Research University of Alabama in Huntsville HuntsvilleAL35805 United States Department of Space Science University of Alabama in Huntsville HuntsvilleAL35805 United States Italian Space Agency Via del Politecnico snc RomaI-00133 Italy University of Urbino Carlo Bo Department of Pure and Applied Sciences Via Santa Chiara 27 UrbinoI-61029 Italy National Institute for Nuclear Physics Section in Florence Via Bruno Rossi 1 Sesto FiorentinoI-50019 Italy National Research Council Institute for the Science and Technology of Plasmas Via Amendola 122/D BariI-70126 Italy Swedish Institute of Space Physics Ångström Laboratory Lägerhyddsvägen 1 UppsalaSE-751 21 Sweden Mullard Space Science Laboratory University College London Holmbury St. Mary DorkingRH5 6NT United Kingdom Université de Lyon Centre National de la Recherche Scientifique École Centrale de Lyon Institut National des Sciences Appliquées de Lyon Université Claude Bernard Lyon 1 Laboratoire de Mécanique des Fluides et d'Acoustique ÉcullyF-69134 France National Institute for Astrophysics Institute for Space Astrophysics and Planetology Via del Fosso del Cavaliere 100 RomaI-00133 Italy National Research Council Institute of Atmospheric Pollution Research c/o University of Calabria RendeI-87036 Italy Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States University of Calabria Department of Physics Ponte Pietro Bucci Cubo 31C RendeI-87036 Italy University of Florence Department of Physics and Astronomy Via Giovanni Sansone 1 Sesto FiorentinoI-50019 Italy National Institute for Astrophysics Astronomical Observatory of Capodimonte Salita Moiariello 16 NapoliI-80131 Italy National Research Council Institute for Photonics and Nanotechnologies Via Trasea 7 PadovaI-35131 Italy Czech Academy of Scie

Evidence for the presence of ion cyclotron waves, driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfvén ion-cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ion cyclotron waves are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating. © 2023, CC BY.

关键词： Solar wind

来源：评论

学校读者我要写书评

暂无评论

GLOBAL OCEANS

引用

BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 2023年第9期104卷 S146-S206页

作者： Johnson, G. C. Lumpkin, R. Met Office Hadley Center Exeter United Kingdom NOAA/OAR Atlantic Oceanographic and Meteorological Laboratory Miami Florida Cooperative Institute for Marine and Atmospheric Studies University of Miami Miami Florida NOAA/NESDIS National Centers for Environmental Information Silver Spring Maryland Cooperative Institute for Climate Ocean and Ecosystem Studies University of Washington Seattle Washington NOAA/OAR Pacific Marine Environmental Laboratory Seattle Washington NASA Goddard Space Flight Center Greenbelt Maryland Morgan State University Baltimore Maryland College of Marine Science University of South Florida St. Petersburg Florida Woods Hole Oceanographic Institution Woods Hole Massachusetts International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Cooperative Institute for Marine and Atmospheric Studies University of Miami Rosenstiel School of Marine Atmospheric and Earth Science University of Miami Miami Florida Science Systems and Applications Inc. Lanham Maryland Science Systems and Applications Inc. Hampton Virginia Scripps Institution of Oceanography University of California San Diego La Jolla California Center for Coastal Physical Oceanography Old Dominion University Norfolk Virginia Australian Antarctic Program Partnership Institute for Marine and Antarctic Studies Australian Research Council Centre of Excellence for Climate Extremes University of Tasmania Hobart Tasmania NOAA/NWS National Centers for Environmental Prediction Climate Prediction Center College Park Maryland NOAA/NESDIS National Centers for Environmental Information Asheville North Carolina Department of Atmosphere Ocean and Earth System Modeling Research Meteorological Research Institute Japan Meteorological Agency Tsukuba Japan National Oceanography Centre Liverpool United Kingdom Flanders Marine Institute InnovOcean Campus Ostend Belgium NOAA/NWS NCWCP Laboratory for Satellite Altimetry College Par

来源：评论

学校读者我要写书评

暂无评论

The Amplitude Frequency Bilateral Modulation Characteristics of Wind Speed Signal

The Amplitude Frequency Bilateral Modulation Characteristics...

引用

2019 IEEE International Conference on Power Data science, ICPDS 2019

作者： Yao, Kun Wan, Jie Ren, Guorui Pan, Mengqi Wang, Wei Cao, Yong Yu, Jilai Shenzhen518055 China Science Institute of Space Environment and Matter Harbin Institute of Technology Harbin150001 China Postdoctoral Research Station of Electrical Engineering Harbin Institute of Technology Harbin150001 China School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China School of Electrical Engineering and Automation Harbin Institute of Technology Harbin150001 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing102206 China

ISBN: (纸本)9781728137759

The sufficient actual big data analysis shows that wind speed has multi-scale amplitude frequency modulation characteristics. There is an evident amplitude modulation effect between the average wind speed and the turbulence variance, and the modulation effect is also found with multi-scale characteristic. The turbulence intensity decreases with the wind speed in a certain range. However, when the wind speed is great in a certain degree, the turbulence intensity almost keeps stable. Simultaneously, both the average wind speed and the center frequency also have the multi-scale modulation effect. The center frequency increases with the wind speed in a certain range. However, when the wind speed is great in a certain degree, the center frequency almost keeps stable. The key discussion was given for this multi-scale amplitude and frequency modulation characteristic resulting from the cascade effect of turbulent energy transport. And the instantaneous model of wind speed and wind power is presented for its great significance of power system's real-time dispatch and optimization control. © 2019 IEEE.

关键词： Big data

来源：评论

学校读者我要写书评

暂无评论

Scattering Center Modeling Using Adaptive Segmental Compressive Sampling

引用

Journal of Beijing Institute of technology 2017年第4期26卷 484-493页

作者： Qifeng Li Kunyi Guo Jiaxin Wang Xinqing Sheng Tianshu Liu Center for Electromagnetic Simulation School of Information and ElectronicsBeijing Institute of Technology Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

In order to deal with aliasing distortions of Doppler frequencies shown in time-frequency representation（ TFR） with aspect undersampling,an approach using adaptive segmental compressive sampling according to the aspect dependencies of the scattering centers is proposed. The random noise problem induced by compressive sampling is solved by employing a series of signal processing techniques of filtering,image transformation and Hough Transform. Three examples are presented to verify the effectiveness of this approach. The comparisons between the built models and the precise scattered fields computed by a well-validated full-wave numerical method are investigated,and the results showgood agreements between each other.

关键词： scattering center undersampling compressive sensing time-frequency representation parameter estimation

来源：评论

学校读者我要写书评

暂无评论

A Machine Learning Approach to Produce a Continuous Solar-Induced Chlorophyll Fluorescence Over the Arctic Ocean

Journal of Geophysical Research: Machine Learning and Comput...

引用

Journal of Geophysical Research: Machine Learning and Computation 2024年第4期1卷

作者： Nima Madani Nicholas C. Parazoo Manfredi Manizza Abhishek Chatterjee Dustin Carroll Dimitris Menemenlis Vincent Le Fouest Atsushi Matsuoka Kelly M. Luis Camila Serra-Pompei Charles E. Miller UCLA Joint Institute for Regional Earth System Science and Engineering Los Angeles CA USA Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA Geosciences Research Division Scripps Institution of Oceanography University of California San Diego La Jolla CA USA Moss Landing Marine Laboratories San José State University Moss Landing CA USA Littoral Environnement et Sociétés UMR 7266 Université de La Rochelle La Rochelle France Institute for the Study of Earth Oceans and Space University of New Hampshire Durham NH USA Center for Climate Change Science Massachusetts Institute of Technology Cambridge MA USA

Phytoplankton primary production is a crucial component of Arctic Ocean (AO) biogeochemistry, playing a pivotal role in carbon cycling by supporting higher trophic levels and removing atmospheric carbon dioxide. The advent of satellite observations measuring chlorophyll a concentration (Chl_a) has provided unprecedented insights into the distribution of AO phytoplankton, enhancing our ability to assess oceanic net primary production (NPP). However, the optical properties of AO waters differ significantly from those of the lower-latitude waters, complicating remotely sensed Chl_a retrievals. To mitigate these deficiencies, solar-induced chlorophyll fluorescence (SIF) has emerged as a valuable tool for gaining physiological insights into the direct photosynthetic processes of the AO. However, the temporal coverage of satellite SIF data makes long-term analysis of Chl_a photosynthetic activity challenging. In this study, we leverage satellite-based SIF measurements from 2018 to 2021 to assess their correlation with a set of predictive factors influencing phytoplankton photosynthesis. Generally, observed SIF over the AO showed a higher correlation with normalized fluorescence line height (NFLH) compared to Chl_a. We extended the temporal coverage of the original SIF data to encompass the period from 2004 to 2020. The extended record revealed noticeable differences between SIF, and satellite-based Chl_a, and NFLH observations. Our novel data set offers a pathway forward to monitor the physiological interactions of phytoplankton with climate changes, promising to significantly improve our understanding of Arctic waters productivity. The application of this data is expected to provide new insights into how phytoplankton respond to environmental shifts, contributing to a more nuanced understanding of their role in high-latitude marine ecosystems. We extrapolated Arctic Ocean red SIF over the 2004–2020 period using a set of predictive variables that impact marine photosynthe

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：