Article
Astronomy & Astrophysics
Q. H. Li, L. Xiang, D. J. Wu, L. Chen, G. Q. Zhao, A. K. Zhao, Y. Zhao, H. Q. Feng
Summary: Using data from the Wind spacecraft between 2005 and 2015, the distribution of alpha temperature anisotropy and its correlation with background plasma parameters in the slow and fast solar wind were investigated. The results show that the distribution of alpha temperature anisotropy depends on the parallel temperature ratio of alpha to proton, the proton temperature anisotropy, the drift velocity of alpha to proton, and the solar wind velocity. The constraining mechanisms on the distribution of alpha temperature anisotropy are different in the slow and fast solar wind.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. Schleich, S. Boro Saikia, U. Ziegler, M. Guedel, M. Bartel
Summary: We generate a model description of the solar wind based on an explicit wave-turbulence-driven heating mechanism and constrain our model with observational data. Our model results, validated against PSP observations, reconstruct the bimodal structure of the solar wind and show reasonable agreement with previously established results and empirical constraints.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Adhikari, G. P. Zank, L-L Zhao, M. Nakanotani, S. Tasnim
Summary: The study developed a theoretical model combining nearly incompressible magnetohydrodynamic (NI MHD) turbulence with a solar wind model that includes electron pressure and heat flux. The results show that the model is consistent with the measurements of fast solar wind by PSP and Helios 2.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Chaitanya Prasad Sishtla, Jens Pomoell, Emilia Kilpua, Simon Good, Farhad Daei, Minna Palmroth
Summary: This study aims to investigate the propagation and evolution of Alfven waves in the solar wind, as well as the response of the solar wind to the injection of monochromatic single-frequency Alfven waves. The results show that the Alfven waves are reflected during their propagation, and the generation of parametric decay instability is suppressed.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Sorriso-Valvo, R. Marino, R. Foldes, E. Leveque, R. D'Amicis, R. Bruno, D. Telloni, E. Yordanova
Summary: This study estimates the energy transfer rate of turbulent cascade in the expanding solar wind by using a linear scaling of the mixed third-order moment of the magnetohydrodynamic (MHD) fluctuations. Data from the Helios 2 spacecraft and direct numerical simulations with the FLAME code were used for interpretation. The results show that the turbulence energy transfer rate decays approximately as a power law of the distance and corresponds to the observed radial temperature profile in the fast wind case.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
C. Shi, M. Velli, O. Panasenco, A. Tenerani, V Reville, S. D. Bale, J. Kasper, K. Korreck, J. W. Bonnell, T. Dudok de Wit, D. M. Malaspina, K. Goetz, P. R. Harvey, R. J. MacDowall, M. Pulupa, A. W. Case, D. Larson, J. L. Verniero, R. Livi, M. Stevens, P. Whittlesey, M. Maksimovic, M. Moncuquet
Summary: The study uses Parker Solar Probe data to explore the nature of solar wind turbulence, revealing that the magnetic field spectrum steepens while the velocity spectrum shape remains unchanged as fluctuations are transported outward. Statistically, faster solar wind has higher Alfvenicity, with outward wave dominance weakening with radial distance and stronger magnetic energy excess found closer to the Sun. Turbulence properties can vary significantly between different solar wind streams, indicating diverse origins and structures such as heliospheric current sheets and velocity shears play important roles in modifying turbulence properties.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Adrover-Gonzalez, J. Terradas, R. Oliver, M. Carbonell
Summary: This study comprehensively investigates the gravitational stability of prominence threads using a basic hydrodynamic model, finding that stable and unstable equilibrium solutions are possible depending on various factors such as initial position, density contrast, length, and total length of magnetic field lines. The results of this study provide new insights into the behavior of threads in curved magnetic fields under the influence of gravity and can help interpret more complex numerical simulations.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Larosa, V Krasnoselskikh, T. Dudok de Wit, O. Agapitov, C. Froment, V. K. Jagarlamudi, M. Velli, S. D. Bale, A. W. Case, K. Goetz, P. Harvey, J. C. Kasper, K. E. Korreck, D. E. Larson, R. J. MacDowall, D. Malaspina, M. Pulupa, C. Revillet, M. L. Stevens
Summary: The first solar encounter of the Parker Solar Probe has revealed the presence of sudden magnetic field deflections in the slow Alfvenic solar wind, known as switchbacks. These structures are often associated with proton velocity enhancements. Statistical analysis shows that switchbacks are Alfvenic in 73% of cases and compressible in 27%. The boundaries of these structures can be interpreted in terms of rotational or tangential discontinuities.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Abbas Raboonik, Paul S. Cally
Summary: A 2.5D numerical model of magnetoacoustic-Alfven linear mode conversions in the partially ionized low solar atmosphere induced by the Hall effect is surveyed. It is found that the Hall effect has a significant impact on the conversion between magnetoacoustic and Alfven waves, especially in the low chromosphere.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
R. Niedziela, K. Murawski, L. Kadowaki, T. Zaqarashvili, S. Poedts
Summary: This paper investigates the heating of the solar chromosphere using a two-fluid model and shows that large-amplitude impulsively generated magnetoacoustic-gravity waves can efficiently heat the chromosphere and generate plasma outflows in the low solar corona.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Jean C. Perez, Sofiane Bourouaine, Christopher H. K. Chen, Nour E. Raouafi
Summary: In this study, the validity of Taylor's hypothesis in analyzing velocity and magnetic field fluctuations in Alfvenic solar wind streams is investigated using data from PSP. The results show that the hypothesis is applicable when PSP is moving nearly perpendicular to the local magnetic field.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Gabriel Pelouze, Tom Van Doorsselaere, Konstantinos Karampelas, Julia M. Riedl, Timothy Duckenfield
Summary: Transverse oscillations of kink waves are found to experience a cutoff in the transition region, preventing them from reaching the corona. However, waves with shorter periods can still propagate to the corona with little attenuation, resulting in heating.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Geeraerts, T. Van Doorsselaere
Summary: In this study, the researchers aimed to investigate if standing slow waves in solar atmospheric structures can trigger the Kelvin-Helmholtz instability (KHI) due to oscillating shear flows at the structures' boundaries. They used linearized nonstationary MHD to develop an analytical model and found that the stability of the interface is determined by a Mathieu equation, concluding that in this simplified setup, a standing slow wave does not trigger the KHI without the involvement of additional physical processes.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Chaitanya Prasad Sishtla, Jens Pomoell, Rami Vainio, Emilia Kilpua, Simon Good
Summary: Alfvenic fluctuations and CMEs have interactions, including the transmission of solar wind fluctuations to CME sheath and the influence of fluctuation frequencies on the extent of CME sheath.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
R. Kieokaew, B. Lavraud, Y. Yang, W. H. Matthaeus, D. Ruffolo, J. E. Stawarz, S. Aizawa, C. Foullon, V Genot, R. F. Pinto, N. Fargette, P. Louarn, A. Rouillard, A. Fedorov, E. Penou, C. J. Owen, T. S. Horbury, H. O'Brien, V Evans, V Angelini
Summary: The study observed the development of KH waves in the solar wind, confirming that KH activity excites magnetic and velocity fluctuations, and tested the instability onset criterion and current sheet geometry analyses.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
J. Y. Lu, Y. T. Xiong, K. Zhao, M. Wang, J. Y. Li, G. S. Peng, M. Sun
Summary: In this paper, a novel bimodal model is proposed to predict a complete sunspot cycle based on comprehensive precursor information. The model combines the implicit and geometric information of the solar cycle with the traditional precursor method and employs a multivariate linear approach, achieving a good performance in the prediction.
ASTROPHYSICAL JOURNAL
(2022)
Article
Multidisciplinary Sciences
Zhifeng Liu, Feng Ding, Jianyong Lu, Yue Zhou, Hetao Chu
Summary: This paper proposes two novel deep learning models, namely BLSTM-ATT and BLSTM-TRA models, for wind speed prediction, which outperform the ECMWF model in terms of prediction accuracy.
COMPTES RENDUS DE L ACADEMIE BULGARE DES SCIENCES
(2022)
Article
Geosciences, Multidisciplinary
Yue Zhou, Jih-Hong Shue, Hiroshi Hasegawa, Jianyong Lu, Ming Wang, Hanxiao Zhang
Summary: Using data from the ARTEMIS spacecraft near the Moon, this study statistically analyzes the properties of Kelvin-Helmholtz (KH) waves and the thickness of initial velocity shear layers on the magnetopause at lunar distance. The results show that at lunar distance, the KH waves have a larger wavelength and thickness compared to those at near-Earth magnetopause. The ratio of wavelength to thickness at lunar distance exceeds the range predicted by the linear theory, indicating that the observed KH waves are not consistent with the fastest growing mode according to linear theory. This study provides insights into the generation and development of KH waves at lunar distance.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Zhiwei Wang, Jianyong Lu, Hongqiao Hu, Jianjun Liu, Zejun Hu, Ming Wang, Bin Li, Xiangcai Chen, Yewen Wu, Hua Zhang, Haiyan Guan
Summary: This study presents a statistical analysis of the effect of radial interplanetary magnetic field (IMF BX) on the Heppner-Maynard Boundary (HMB) midnight latitude in the solar wind-magnetosphere-ionosphere (S-M-I) coupling. It is found that the IMF BX plays an important role in determining the HMB midnight latitude, which is negatively correlated with the magnitude of IMF BX and solar wind speed.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Meng Sun, Zheng Li, Jingyuan Li, Jianyong Lu, Chunli Gu, Mengbin Zhu, Yufeng Tian
Summary: The study investigates the variations of neutral temperature in the mesosphere and lower thermosphere region during the intense geomagnetic storm in September 2017 using observations and simulations. Observations show significant temperature changes during the storm, with hemispheric asymmetry. The simulations generally agree with observations but show differences in temperature changes at different latitudes.
Article
Astronomy & Astrophysics
Kenneth Iluore, Jianyong Lu, Francisca Okeke, Kesyton Oyamenda Ozegin
Summary: This paper conducts a comparative investigation of the Total Electron Content (TEC) values obtained from the NeQuick-2 and IRI-Plas 2017 models. The results show that both models exhibit good agreement with the observed TEC values from GPS measurements, although there are some overestimations and underestimations during certain times of the day. The NeQuick-2 model generally performs better and shows improvement in certain seasons and stations when compared to the IRI-Plas model. However, the quality of forecasting for both models can be influenced by solar activity and varies across seasons and stations. There is also a latitudinal dependence for both models in which the prediction error decreases with increasing latitudes.
Article
Engineering, Aerospace
Kenneth Iluore, Jianyong Lu
Summary: This paper explores the application of deep learning models, such as LSTM and GRU, in forecasting ionospheric GPS_VTEC. It compares the performance of these models with MLP neural networks, GIM_TEC, and the IRI-Plas 2017 models. The study finds that the GRU unit achieves the highest correlation coefficient and the lowest prediction error, indicating its superior prediction accuracy compared to other models.
ADVANCES IN SPACE RESEARCH
(2022)
Article
Astronomy & Astrophysics
Guanchun Wei, Jianyong Lu, Wenbin Wang, Yufeng Tian, Jingyuan Li, Shiping Xiong, Meng Sun, Fuzhen Shen, Zheng Li, Hua Zhang, Jingqi Cui, Chaolei Yang, Jingrui Yao, Shuwen Jiang, Zhixin Zhu, Jingye Wang
Summary: Using SABER temperature data, we investigated the response of the mesosphere and lower thermosphere to two medium geomagnetic storms with different durations. The temperature increase in the Southern hemisphere during the longer-duration storm was 40 K, while it was less than 10 K for the shorter-duration event. Simulations showed that longer-duration storms result in more particles and energy input, leading to stronger forces and faster horizontal wind, which then cause greater temperature increases in the MLT region through adiabatic heating/cooling and vertical advection. Therefore, the duration of the storm is important for understanding the temperature response in the MLT region.
Article
Astronomy & Astrophysics
H. Y. Sui, M. Wang, J. Y. Lu, Y. Zhou, J. Wang
Summary: Based on the MAVEN mission, the intensity and orientation of the IMF have been found to affect the location and shape of the Martian bow shock. When the IMF intensity increases, the bow shock moves linearly away from Mars. Under the radial IMF condition, the subsolar and flank regions of the Martian bow shock are closer to Mars. When the Y component of the IMF is dominant, the cross section of the Martian bow shock elongates in the north-south direction.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Shiping Xiong, Jingyuan Li, Guanchun Wei, Jianyong Lu, Yufeng Tian, Xiaoping Zhang, Shuai Fu, Meng Sun, Zheng Li, Hua Zhang, Jingqi Cui, Shuwen Jiang, Chaolei Yang
Summary: Observations from SABER and simulations from WACCM-X were used to analyze the effects of solar proton events (SPEs) on mesospheric ozone at high latitudes. The results showed that high-latitude mesospheric ozone decreased significantly during SPEs, with a larger decrease in the North Hemisphere compared to the South Hemisphere. The simulations also revealed a significant increase in NOx and HOx during SPEs, with the changes exhibiting hemispheric asymmetries.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)
Article
Multidisciplinary Sciences
H. X. Zhang, J. Y. Lu, M. Wang
Summary: A parametric study is conducted to investigate the energy transfer of the solar wind across the magnetopause entering the magnetosphere. The study analyzes the distribution of mechanical and electromagnetic energy under different interplanetary magnetic field (IMF) orientations and compares their characteristics. The results show that the energy transfer and interaction at the magnetopause vary with the IMF orientation, and the energy distribution exhibits different patterns under different IMFs.
SCIENTIFIC REPORTS
(2023)
Article
Meteorology & Atmospheric Sciences
Jingyuan Li, Guanchun Wei, Wenbin Wang, Qinshun Luo, Jianyong Lu, Yufeng Tian, Shiping Xiong, Meng Sun, Fuzhen Shen, Tao Yuan, Xiaoping Zhang, Shuai Fu, Zheng Li, Hua Zhang, Chaolei Yang
Summary: This study reveals the nature and mechanisms of temperature variations in the mesosphere and lower thermosphere (MLT) at high latitudes. The temperature in the MLT region shows increases and decreases at different time intervals during geomagnetic storms. The main drivers of these temperature changes are adiabatic heating/cooling and vertical advection.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2023)
Article
Astronomy & Astrophysics
M. Wang, K. Xu, J. Y. Lu, M. X. Yin, H. Y. Sui, Z. J. Guan, J. Q. Zhang
Summary: In this paper, the effect of interplanetary magnetic field (IMF) intensity and orientation on the Martian magnetic pileup boundary (r(0)) and pressure balance is studied using a three-dimensional multispecies MHD model. The results show that the magnitude of the Y or Z-component of IMF influences r(0), while the radial IMF component has little effect. The ratio of the IMF Y and Z-components to IMF intensity controls the impact of the IMF cone angle on r(0) and compression degree of the magnetic field. The difference in the IMF effect on the size of the Martian magnetic pileup boundary reveals different solar wind interactions with a magnetized and unmagnetized planet.
ASTROPHYSICAL JOURNAL
(2023)
Article
Geosciences, Multidisciplinary
Xi Wang, Jianyong Lu, Ming Wang, Yue Zhou, Yufei Hao
Summary: This paper investigates the influence of high-speed jets (HSJs) on the position of the magnetopause under long-term radial interplanetary magnetic fields (IMFs). The study finds that under quasi-radial IMF conditions, the magnetopause expands and then is locally indented by HSJs.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Haibing Ruan, Jiuhou Lei, Jianyong Lu, Fen Tang
Summary: An empirical model of total electron content is developed based on the superposition of the tide-like components. The seasonal and interannual behaviors in the amplitudes and phases of tide-like signatures in the ionosphere are reproduced. The developed empirical model has a good performance in reconstructing the variabilities in the global ionosphere.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)