We present a broad review of 1/f noise observations in the heliosphere, and discuss and complement the theoretical background of generic 1/f models as relevant to NASA's PUNCH mission. First observed in the voltage fluctuations of vacuum tubes, the scale-invariant 1/f spectrum has since been identified across a wide array of natural and artificial systems, including heart rate fluctuations and loudness patterns in musical compositions. In the solar wind, the interplanetary magnetic field trace spectrum exhibits 1/f scaling within the frequency range from around 2e-6 Hz to around 1e-3 Hz at 1 au. One compelling mechanism for the generation of 1/f noise is the superposition principle, where a composite 1/f spectrum arises from the superposition of a collection of individual power-law spectra characterized by a scale-invariant distribution of correlation times. In the context of the solar wind, such a superposition could originate from scale-invariant reconnection processes in the corona. Further observations have detected 1/f signatures in the photosphere and corona at frequency ranges compatible with those observed at 1 au, suggesting an even lower altitude origin of 1/f spectrum in the solar dynamo itself. This hypothesis is bolstered by dynamo experiments and simulations that indicate inverse cascade activities, which can be linked to successive flux tube reconnections beneath the corona, and are known to generate 1/f noise possibly through nonlocal interactions at the largest scales. Conversely, models positing in situ generation of $1/f$ signals face causality issues in explaining the low-frequency portion of the 1/f spectrum. Understanding 1/f noise in the solar wind may inform central problems in heliospheric physics, such as the solar dynamo, coronal heating, the origin of the solar wind, and the nature of interplanetary turbulence.
Polarimeter to Unify the Corona and Heliosphere (PUNCH)
Southwest Research Institute（西南研究所）；National Center for Atmospheric Research / High Altitude Observatory（国家大气研究中心/高空观测站）；Naval Research Laboratory（海军研究实验室）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；George Mason University（乔治梅森大学）；Indian Institute of Astrophysics（印度天体物理研究所）；University of Reading（雷丁大学）；NOAA Space Weather Prediction Center（美国国家海洋和大气管理局空间天气预测中心）；University of Sydney（悉尼大学）；University of Delaware（特拉华大学）；University of Colorado（科罗拉多大学）；Cooperative Institute for Research in Environmental Sciences（环境科学研究合作学院）；Catholic University of America（美国天主教大学）；Johns Hopkins University Applied Physics Laboratory（约翰斯·霍普金斯大学应用物理实验室）；University of California, San Diego（加利福尼亚大学圣地亚哥分校）；Stellar Solutions Inc.（恒星解决方案公司）；Princeton University（普林斯顿大学）；University of Aberystwyth（阿伯里斯特威斯大学）；National Center for Radio Astrophysics（国家射电天文中心）；Boston College（波士顿学院）；European Space Agency（欧洲空间局）
Polarization Diagnostics Applied to Coronal Mass Ejections and the Background Solar Wind
National Center for Atmospheric Research（国家大气研究中心）；Southwest Research Institute（西南研究所）；CIRES, University of Colorado（科罗拉多大学联合空间环境研究中心）；University of Colorado（科罗拉多大学）；Aberystwyth University（阿伯里斯特威斯大学）；Johns Hopkins University（约翰斯·霍普金斯大学）；Boston College（波士顿学院）
Solar Ring (SOR) is a proposed space science mission to monitor and study the Sun and inner heliosphere from a full 360° perspective in the ecliptic plane. It will deploy three 120°-separated spacecraft on the 1-AU orbit. The first spacecraft, S1, locates 30° upstream of the Earth, the second, S2, 90° downstream, and the third, S3, completes the configuration. This design with necessary science instruments, e.g., the Doppler-velocity and vector magnetic field imager, wide-angle coronagraph, and in-situ instruments, will allow us to establish many unprecedented capabilities: (1) provide simulta…
Non-equilibrium ionization (NEI) is a key process often times neglected when modeling astrophysical plasmas with thermodynamical timescales much shorter than the timescales for ionization and recombination. In this paper, we perform NEI modeling on a magnetohydrodynamic (MHD) simulation of the solar wind during the Whole Sun Month (Carrington Rotation 1913 from 1996 August 22 to September 18), and compare the resulting charge state distributions with in situ measurements made with the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses. We trace the wind trajectory back to 20$R_\odot$ u…
This review summarizes our current understanding of the outer heliosphere and local interstellar medium (LISM) inferred from observations and modeling of interplanetary Lyman-$α$ emission. The emission is produced by solar Lyman-alpha photons (121.567 nm) backscattered by interstellar H atoms inflowing to the heliosphere from the LISM. Studies of Lyman-alpha radiation determined the parameters of interstellar hydrogen within a few astronomical units from the Sun. The interstellar hydrogen atoms appeared to be decelerated, heated, and shifted compared to the helium atoms. The detected decelerat…
Solar Orbiter, the first mission of ESA's Cosmic Vision 2015-2025 programme and a mission of international collaboration between ESA and NASA, will explore the Sun and heliosphere from close up and out of the ecliptic plane. It was launched on 10 February 2020 04:03 UTC from Cape Canaveral and aims to address key questions of solar and heliospheric physics pertaining to how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To answer these, the mission carries six remote-sensing instruments to observe the Sun and the solar corona, and four in-situ instrumen…
This White Paper argues for the urgent need for the multi-vantage/multi-point observations of the Sun and the heliosphere in the framework of six (6) key science objectives. We further emphasize the critical importance of 5D-``space'': three spatial, one temporal and the magnetic field components. The importance of such observations cannot be overstated both for scientific research and the operational space weather forecast.
To make progress on the open questions on CME/CIR propagation, their interactions and the role and nature of the ambient solar wind, we need spatially resolved coverage of the inner heliosphere -- both in-situ and (critically) imaging -- at temporal scales matching the evolutionary timescales of these phenomena (tens of minutes to hours), and from multiple vantage points. The polar vantage is uniquely beneficial because of the wide coverage and unique perspective it provides. The ultimate goal is to achieve full $4π$ coverage of the solar surface and atmosphere by 2050.
Long-term synoptic observations of the Sun are critical for advancing our understanding of Sun as an astrophysical object, understanding the solar irradiance and its role in solar-terrestrial climate, for developing predictive capabilities of solar eruptive phenomena and their impact on our home planet, and heliosphere in general, and as a data provider for the operational space weather forecast. We advocate for the development of a ground-based network of instruments provisionally called ngGONG to maintain critical observing capabilities for synoptic research in solar physics and for the oper…
Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate? (2) How do solar transients drive heli…
Radio spectroscopy provides a unique inspection perspective for solar and space weather research, which can reveal the plasma and energetic electron information in the solar corona and inner heliosphere. However, Radio-Frequency Interference (RFI) from human activities affects sensitive radio telescopes, and significantly affects the quality of observation. Thus, RFI detection and mitigation for the observations is necessary to obtain high quality, science-ready data. The flagging of RFI is particularly challenging for the solar and space weather observations at low frequency, because the sola…
Continuous Ultra-Low-Frequency Solar Radio Monitoring with ALBATROS from the High Arctic
McGill University（麦吉尔大学）；Trottier Space Institute, McGill University（特罗蒂尔太空研究所，麦吉尔大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）；Princeton University（普林斯顿大学）；McMaster University（麦克马斯特大学）
Understanding Solar Flares and Energetic Events: Open questions, observational requirements, and instrumental needs over the coming decade
University of Sheffield（谢菲尔德大学）；University of Glasgow（格拉斯哥大学）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；University of Manchester（曼彻斯特大学）；University of Cambridge（剑桥大学）；Czech Academy of Sciences（捷克科学院）；Rutherford Appleton Laboratory（鲁瑟福阿普尔顿实验室）；Bay Area Environmental Research Institute（湾区环境研究所）；Mullard Space Science Laboratory, University College London（伦敦大学学院穆拉德空间科学实验室）；Dublin Institute for Advanced Studies（都柏林高等研究院）；Northumbria University（诺森比亚大学）；Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦莱布尼茨天体物理研究所）；Lockheed Martin Solar and Astrophysics Laboratory（洛克希德·马丁太阳与天体物理实验室）；University of St. Andrews（圣安德鲁斯大学）；Durham University（杜伦大学）
Potential Solar Precursors to Magnetic Switchbacks
Inter-University Centre for Astronomy and Astrophysics（大学间天体物理中心）；Max Planck Institute for Solar System Research（马克斯·普朗克太阳系统研究所）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）；Space Research and Technology Institute, Bulgarian Academy of Sciences（保加利亚科学院空间技术与研究所）；Heliophysics Science Division, NASA Goddard Space Flight Center（NASA戈达德太空飞行中心日球物理科学部）；Earth, Planetary and Space Sciences, University of California, Los Angeles（加州大学洛杉矶分校地球、行星与空间科学系）；LPC2E, OSUC, Univ Orleans, CNRS, CNES（奥尔良大学、国家科学研究中心、国家空间研究中心 LPC2E 实验室）；Sorbonne Université, École polytechnique, Institut Polytechnique de Paris, Université Paris Saclay, Observatoire de Paris-PSL, CNRS, Laboratoire de Physique des Plasmas (LPP)（索邦大学、巴黎综合理工学院、巴黎理工学院、巴黎萨克雷大学、巴黎天文台-PSL、CNRS、等离子体物理实验室（LPP））；University of Ioannina（约阿尼纳大学）；Johns Hopkins Applied Physics Laboratory（约翰斯·霍普金斯大学应用物理实验室）
