Article
Environmental Sciences
Steven Dewitte, Jan Cornelis, Mustapha Meftah
Summary: This study analyzed the space measurements of Total Solar Irradiance (TSI) and derived a regression model to reproduce the daily variations of TSI. The reconstruction of TSI based on the Sunspot Number confirmed the existence of a 105-year Gleissberg cycle, with the TSI level of the current grand minimum only slightly higher than that of the 18th century.
Article
Geosciences, Multidisciplinary
Weiyi Sun, Jian Liu, Bin Wang, Deliang Chen, Lingfeng Wan, Jing Wang
Summary: This study investigates the influence of solar activity on the Asian summer monsoon (ASM) at different time scales. Simulation results suggest that solar forcing can significantly affect ASM precipitation on a 300-600-year periodicity during the middle-late Holocene. Proxy data also support this multi-centennial variation. The western North Pacific circulation system plays a key role in modulating the ASM variation, through enhancing the south Asia-WNP monsoon trough.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Conor D. MacBride, David B. Jess, Elena Khomenko, Samuel D. T. Grant
Summary: Magnetohydrodynamic (MHD) simulations assume fully ionized plasma, but in the lower solar atmosphere, reduced temperature leads to partial ionization. The interaction between neutral and ionized components produces ambipolar diffusion. Studying the propagation of magnetoacoustic waves above sunspot umbra, we find that ambipolar diffusion plays a pivotal role in wave characteristics in weakly ionized low density regions. It is important to consider ambipolar diffusion in simulations and interpretation of solar observations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Qirong Jiao, Wenlong Liu, Dianjun Zhang, Jinbin Cao
Summary: This study investigates the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that low-latitude sunspot number has a larger effect on solar wind speed, and adding latitude-dependent sunspot data improves the accuracy of solar wind speed prediction.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Belur Ravindra, Partha Chowdhury, Pratap Chandra Ray, Kumaravel Pichamani
Summary: This article investigates the temporal and periodic variations of the Sun's monthly hemispheric sunspot number and sunspot group area using data from the Kodaikanal Observatory from 1905 to 2016. The study reveals that the variations in sunspot number and group area differ between the northern and southern hemispheres and peak at different times in the solar cycle. It also identifies Cycle 19 as having the maximum amplitude and Cycle 24 as the weakest for sunspot number, while Cycle 15 is the weakest for group area. The study further analyses the periodicities and coupling between the opposite hemispheres, finding the presence of double peaks and violation of the odd-even rule.
ASTROPHYSICAL JOURNAL
(2022)
Article
Engineering, Aerospace
V. M. Efimenko, V. G. Lozitsky
Summary: We propose a prediction for the amplitude of the 25th solar cycle based on analysis of data from 24 previous cycles. The prediction depends on initial assumptions, such as which section of the growth curve is considered and whether all cycles are included. The assumption of a monotonic or non-monotonic growth curve also plays a role.
ADVANCES IN SPACE RESEARCH
(2023)
Article
Astronomy & Astrophysics
Yuming Wang, Jingnan Guo, Gang Li, Elias Roussos, Junwei Zhao
Summary: Research has found that the intensity of galactic cosmic rays (GCRs) is modulated by solar activity, with a lag behind the variation in sunspot number (SSN). The study has also revealed that the opening of the solar magnetic field lags behind SSN before the solar wind arrives. Furthermore, low latitude regions contribute significantly to the total open magnetic flux.
ASTROPHYSICAL JOURNAL
(2022)
Article
Multidisciplinary Sciences
Hitoshi Hasegawa, Nagayoshi Katsuta, Yasushi Muraki, Ulrich Heimhofer, Niiden Ichinnorov, Hirofumi Asahi, Hisao Ando, Koshi Yamamoto, Masafumi Murayama, Tohru Ohta, Masanobu Yamamoto, Masayuki Ikeda, Kohki Ishikawa, Ryusei Kuma, Takashi Hasegawa, Noriko Hasebe, Shoji Nishimoto, Koichi Yamaguchi, Fumio Abe, Ryuji Tada, Takeshi Nakagawa
Summary: Understanding climate variability and stability under extremely warm 'greenhouse' conditions in the past is crucial for future climate predictions. Scientists have studied lake deposits from the late Early Cretaceous in southeastern Mongolia, and found continuous records of decadal to orbital-scale continental climate variability. The results indicate that solar activity influences climate on decadal to centennial timescales, and internal processes may amplify millennial-scale variations.
SCIENTIFIC REPORTS
(2022)
Article
Astronomy & Astrophysics
Xinyi Wang, Chaowei Jiang, Xueshang Feng, Aiying Duan, Xinkai Bian
Summary: This study used a full 3D MHD simulation and data-constrained approach to explore the relationship between sunspot rotation and solar eruption, revealing the mechanism behind complex MHD evolution. The simulation successfully demonstrated homologous eruptions and showed reasonable consistency with observational data.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
A. Bruno, M. Martucci, F. S. Cafagna, R. Sparvoli, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V Bonvicini, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, A. M. Galper, S. Koldashov, S. Koldobskiy, A. N. Kvashnin, A. Lenni, A. A. Leonov, V. V. Malakhov, L. Marcelli, N. Marcelli, A. G. Mayorov, W. Menn, M. Merge, E. Mocchiutti, A. Monaco, N. Mori, V. V. Mikhailov, R. Munini, G. Osteria, B. Panico, P. Papini, M. Pearce, P. Picozza, M. Ricci, S. B. Ricciarini, M. Simon, A. Sotgiu, P. Spillantini, Y. Stozhkov, A. Vacchi, E. Vannuccini, G. Vasilyev, S. A. Voronov, Y. T. Yurkin, G. Zampa, N. Zampa, T. R. Zharaspayev
Summary: The study examined solar-cycle variations of >80 MeV proton flux intensities in the lower edge of the inner radiation belt using data from the PAMELA mission. The analyzed data covered an approximately 8-year interval and explored intensity temporal variations as a function of drift shell and proton energy, offering important constraints for modeling the low-altitude particle radiation environment at the highest trapping energies.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Hongbing Zhu, Wenwei Zhu, Haoze Chen, Mu He
Summary: An optimized long short-term memory model is proposed to forecast the peak amplitude and reaching time of Solar Cycle 25 (SC-25) based on smoothed monthly F (10.7) and nonsmoothed monthly sunspot area (SSA) data. The model achieves low forecasting errors for previous cycles and predicts a stronger SC-25 with a peak amplitude of 156.3 for F (10.7) and 2562.5 for SSA, reaching its peak at the beginning of 2025.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Tomoya Iju, Koji Murata, Bruno P. Besser
Summary: The study analyzed Daniel Mogling's original sunspot observations from 1626-1629, revising the observational dates and group numbers, and compared them with contemporary observations. Results indicated that sunspots in the 1620s migrated to lower heliographic latitudes, emphasizing their location in the declining phase of solar cycle -12.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Alla V. Suvorova
Summary: In this study, variations in the occurrence of high-energy electrons (>30 keV) in the forbidden zone over a 25-year period were analyzed. The analysis revealed the highest correlations between the occurrence of these Forbidden Energetic Electrons (FEE) and the F10.7 solar activity index (-0.87) and the Alfven Mach number of the upstream solar wind (0.76). A power expression incorporating these parameters, as well as plasma beta and interplanetary magnetic field strength, was obtained through multiparameter regression analysis, with a total correlation coefficient of 0.94. The role of the high-latitude ionosphere conductivity in the mechanism of ERB electron penetration into the forbidden zone is discussed.
Article
Astronomy & Astrophysics
Shuai Fu, Xiaoping Zhang, Lingling Zhao, Yong Li
Summary: This paper investigates Galactic cosmic-ray variations over solar cycles 23 and 24, revealing record-breaking GCR intensities during the solar minimum in 2019-2020 and changes in the modulation environment that reduce solar modulation levels, providing a plausible explanation for the intense GCR levels in interplanetary space.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2021)
Article
Geosciences, Multidisciplinary
Ying Zou, Brian M. Walsh, Li-Jen Chen, Jonathan Ng, Xueling Shi, Chih-Ping Wang, Larry R. Lyons, Jiang Liu, Vassilis Angelopoulos, Kathryn A. McWilliams, J. Michael Ruohoniemi
Summary: The temporal nature of magnetic reconnection at the magnetopause has been a subject of study. It has been found that under quasi-steady solar wind driving, reconnection is initially inactive, then activates and proceeds continuously but unsteadily. The reconnection electric field shows variations at frequencies below 10 mHz, with amplitudes representing 30%-60% of the peak reconnection electric field. The unsteadiness of reconnection can be explained by fluctuating magnetic fields in the turbulent magnetosheath.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Allan R. Macneil, Mathew J. Owens, Adam J. Finley, Sean P. Matt
Summary: The study evaluates the heliospheric portion of two-step backmapping, finding that mapping using models can achieve good average agreement with observed data, but with significant standard deviation. It also suggests that previous assumptions about interplanetary acceleration and solar wind corotation height may have been overestimated, and that error cancellation may contribute to the performance of ballistic mapping.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. Rahmanifard, A. P. Jordan, W. C. Wet, N. A. Schwadron, J. K. Wilson, M. J. Owens, H. E. Spence, P. Riley
Summary: Since the beginning of the space age, the Sun has been experiencing elevated activity, with the current secular maximum being the longest in the last 9300 years. However, there has been a decline in overall solar activity since the end of solar cycle 21, leading to an increase in the fluxes of galactic cosmic rays. Researchers have investigated the correlation between cosmic ray modulation, heliospheric magnetic field, and solar wind speed over the last 24 solar cycles to identify trends that could predict future solar activity. Based on their findings, they predict that solar cycle 25 will be as weak as or weaker than solar cycle 24, indicating that the Sun may have entered a secular minimum that will last for two more cycles.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Astronomy & Astrophysics
Yutian Chi, Chenglong Shen, Christopher Scott, Mengjiao Xu, Mathew Owens, Yuming Wang, Mike Lockwood
Summary: Solar wind stream interaction regions (SIRs) and corotating interaction regions (CIRs) have significant impacts on space weather and require advanced warning. Recent solar missions propose using the Solar Terrestrial Relations Observatory (STEREO-B) spacecraft to predict CIR arrival time. The correlation coefficients between CIRs detected by STEREO-B and Wind spacecraft show that solar wind velocity structure is more persistent than magnetic field or ion density. By assuming stable and ideal corotation, CIRs can be accurately predicted several days in advance when the separation angle between STEREO-B and Wind is within certain limits.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Astronomy & Astrophysics
Luke Barnard, Mathew Owens, Chris Scott, Matthew Lang, Mike Lockwood
Summary: We present SIR-HUXt, an integration of a sequential importance resampling data assimilation scheme with the HUXt solar wind model. SIR-HUXt assimilates the time-elongation profiles of Coronal Mass Ejection (CME) fronts and performs well in a simple synthetic CME scenario.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)
Article
Astronomy & Astrophysics
Harriet Turner, Matthew Lang, Mathew Owens, Andy Smith, Pete Riley, Mike Marsh, Siegfried Gonzi
Summary: Accurate and timely space weather forecasting requires knowledge of the ambient solar wind. Data assimilation has shown potential for improving the forecast skill of near-Earth solar wind conditions. Assimilation of both near-real-time and science observations can significantly reduce the mean absolute error of solar wind speed.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)
Article
Astronomy & Astrophysics
Lauren A. A. James, Christopher J. J. Scott, Luke A. A. Barnard, Mathew J. J. Owens, Matthew S. S. Lang, Shannon R. R. Jones
Summary: Accurately forecasting the arrival of coronal mass ejections (CMEs) at Earth is important, and it depends on accurate modeling of the event. In this study, the researchers used the HUXt solar wind model to analyze CME distortion and estimate the arrival time error (ATE) for a specific CME event. By comparing the time-elongation profiles captured by HI instruments with the modeled CME profiles, they were able to infer the longitudinal extent of the CME. They also showed that accounting for CME distortion is crucial for accurate estimates of the CME arrival time.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)
Article
Astronomy & Astrophysics
M. Lockwood
Summary: The study compares the IAGA-endorsed Polar Cap Indices (PCN and PCS) for the northern and southern hemispheres from 1998 to 2018. The effects of different magnetic coordinates of the two stations, Thule in Greenland and Vostok in Antarctica, are investigated. The results show that PCS consistently correlates slightly better with solar wind parameters than PCN, and the correlations are highest for the predicted magnetopause reconnection voltage.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Lockwood, M. J. Owens, L. A. Barnard
Summary: We study the variations in Universal Time (UT) in the magnetospheric response to Coronal Mass Ejection (CME) impacts, specifically analyzing the two CMEs that caused the destruction of 38 out of 49 Starlink satellites in early February 2022. Our analysis involves the Expanding-Contracting Polar Cap model to examine changes in ionospheric polar caps and an eccentric dipole model of the geomagnetic field to quantify UT variations caused by the inductive effect of diurnal motions of the geomagnetic poles in a geocentric-solar frame of reference. Our findings demonstrate that the power deposited in the thermosphere varies significantly based on the arrival UT of the CMEs, and that in the events of early February 2022, both CMEs arrived at the optimal UT to cause maximum thermospheric heating.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Review
Astronomy & Astrophysics
Mike Lockwood, Stephen E. Milan
Summary: The study investigates the dependencies of Earth's magnetosphere on Universal Time, particularly the consequences of Earth's magnetic axis not being aligned with the rotational axis. The eccentricity of the magnetic axis in the Southern hemisphere and the deviation in longitudinal separation of the magnetic poles result in unequal and non-canceling variations in the two hemispheres. The study also explores the inductive effect of polar cap motions in a geocentric-solar frame and examines the response of the magnetosphere-ionosphere system to different polarities of the Interplanetary Magnetic Field.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2023)
Article
Environmental Sciences
Xiang-Yu Wang, Qing-He Zhang, Chi Wang, Yong-Liang Zhang, Bin-Bin Tang, Zan-Yang Xing, Kjellmar Oksavik, Larry R. Lyons, Michael Lockwood, Qiu-Gang Zong, Guo-Jun Li, Jing Liu, Yu-Zhang Ma, Yong Wang
Summary: According to magnetohydrodynamic simulations and observations from DMSP and THEMIS, the open magnetic flux in the polar cap almost disappeared and the Earth's magnetotail was compressed into a calabash shape during the coronal mass ejection on April 9th, 2015. The study provides direct observations of the disappearance of open-flux polar cap characterized by merging poleward edges of a conjugate horse-collar aurora in both hemispheres' polar ionosphere. This phenomenon is caused by solar wind plasma captured by continuous dual-lobe magnetic reconnections, resulting in the formation of a short calabash-shaped magnetotail.
COMMUNICATIONS EARTH & ENVIRONMENT
(2023)
Article
Astronomy & Astrophysics
Bingkun Yu, Yutian Chi, Mathew Owens, Christopher J. Scott, Chenglong Shen, Xianghui Xue, Luke Barnard, Tielong Zhang, Daniel Heyner, Hans-Ulrich Auster, Ingo Richter, Jingnan Guo, Beatriz Sanchez-Cano, Zonghao Pan, Zhuxuan Zou, Zhenpeng Su, Zhiyong Wu, Guoqiang Wang, Sudong Xiao, Kai Liu, Xinjun Hao, Yiren Li, Manming Chen, Xiankang Dou, Mike Lockwood
Summary: This study presents a comprehensive review of previous studies on the AP test. The authors use an extended AP test method and apply it to several samples from the Sloan Digital Sky Survey. They calibrate the test using Multiverse simulations and focus on testing the consistency of the flat Lambda cold dark matter model with observations. The results indicate a strong tension with the flat ACDM model and highlight the potential need for a new paradigm of cosmology.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yutian Chi, Chenglong Shen, Junyan Liu, Zhihui Zhong, Mathew Owens, Christopher Scott, Luke Barnard, Bingkun Yu, Daniel Heyner, Hans-Ulrich Auster, Ingo Richter, Yuming Wang, Tielong Zhang, Jingnan Guo, Beatriz Sanchez-Cano, Zonghao Pan, Zhuxuan Zou, Mengjiao Xu, Long Cheng, Zhenpeng Su, Dongwei Mao, Zhiyong Zhang, Can Wang, Zhiyong Wu, Guoqiang Wang, Sudong Xiao, Kai Liu, Xinjun Hao, Yiren Li, Manming Chen, Mike Lockwood
Summary: This study reports two multipoint interplanetary coronal mass ejections (ICMEs) detected by the Tianwen-1 and Mars Atmosphere and Volatile Evolution spacecraft at Mars, and the BepiColombo spacecraft upstream of Mars. The findings highlight the importance of background solar wind in determining the interplanetary evolution and global morphology of ICMEs up to Mars distance. Observations from multiple locations are invaluable for space weather studies at Mars and merit more exploration in the future.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Stephanie L. Yardley, Christopher J. Owen, David M. Long, Deborah Baker, David H. Brooks, Vanessa Polito, Lucie M. Green, Sarah Matthews, Mathew Owens, Mike Lockwood, David Stansby, Alexander W. James, Gherardo Valori, Alessandra Giunta, Miho Janvier, Nawin Ngampoopun, Teodora Mihailescu, Andy S. H. To, Lidia van Driel-Gesztelyi, Pascal Demoulin, Raffaella D'Amicis, Ryan J. French, Gabriel H. H. Suen, Alexis P. Rouillard, Rui F. Pinto, Victor Reville, Christopher J. Watson, Andrew P. Walsh, Anik De Groof, David R. Williams, Ioannis Zouganelis, Daniel Mueller, David Berghmans, Frederic Auchere, Louise Harra, Udo Schuehle, Krysztof Barczynski, Eric Buchlin, Regina Aznar Cuadrado, Emil Kraaikamp, Sudip Mandal, Susanna Parenti, Hardi Peter, Luciano Rodriguez, Conrad Schwanitz, Phil Smith, Luca Teriaca, Cis Verbeeck, Andrei N. Zhukov, Bart De Pontieu, Tim Horbury, Sami K. Solanki, Jose Carlos del Toro Iniesta, Joachim Woch, Achim Gandorfer, Johann Hirzberger, David Orozco Suarez, Thierry Appourchaux, Daniele Calchetti, Jonas Sinjan, Fatima Kahil, Kinga Albert, Reiner Volkmer, Mats Carlsson, Andrzej Fludra, Don Hassler, Martin Caldwell, Terje Fredvik, Tim Grundy, Steve Guest, Margit Haberreiter, Sarah Leeks, Gabriel Pelouze, Joseph Plowman, Werner Schmutz, Sunil Sidher, William T. Thompson, Philippe Louarn, Andrei Federov
Summary: The Slow Wind SOOP was developed to utilize the instruments on board the Solar Orbiter mission to study the origin and formation of the slow solar wind. It successfully linked remote-sensing and in situ measurements of slow wind originating from magnetic field boundaries. Coordinated observation campaigns were conducted with Hinode and IRIS. The analysis showed that slow wind from two target regions arrived at the spacecraft with velocities between 210 and 600 km/s.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
