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  • HengLe Du, BinBin Ni, Xiao-Dong Wang, Shahab Fatemi, Xing Cao
    Earth and Planetary Physics. 2026, 10(3): 417-426.

    As a planet lacking a global magnetic field, Mars interacts directly with the solar wind, forming an induced magnetosphere that mediates energy transfer and atmospheric ion loss. The topology of this interaction and the resulting atmospheric ion escape are strongly influenced by the orientation of the interplanetary magnetic field (IMF). In this study, we utilize a hybrid model to investigate how variations in the IMF orientation shape ion current systems and atmospheric ion escape rates of O+, O2+, CO2+. We first perform simulations with a constant |Bsw|, where varying the IMF cone angle results in different strengths of the convective electric field (Esw = Vsw × Bsw). Our results suggest that the spatial morphology of ion plumes undergoes a substantial evolution, forming a distinct cross-flow plume as the IMF rotates from perpendicular to parallel. These ion plumes exhibit a mass-dependent deflection, where heavier CO2+ travel farther with larger gyroradii than lighter O+, acting as an asymmetric obstacle in the –YMSE hemisphere (where MSE is the Mars solar electric coordinate frame). In turn, the solar wind proton current develops pronounced asymmetries under a parallel IMF, becoming largely diffused in the −YMSE hemisphere because of the interaction with the additional plume obstacles. Consequently, the ion escape rates exhibit a nonmonotonic dependence on the IMF orientation, peaking under a parallel  IMF as escape shifts from a tail- to plume-dominated flow with substantial upstream enhancement. To decouple the effects of IMF geometry from those of the convective electric field, we further conduct a comparative simulation with constant  By  (hence constant |Esw|), where the cone angle is varied by changing the Bx component while allowing |Bsw| to vary. With increasing Bx toward a parallel orientation, the total field magnitude grows, causing the Alfvén Mach number (MA) to decrease from super-Alfvénic to trans-Alfvénic and ultimately to sub-Alfvénic values. Within the range from perpendicular to a 30° cone angle, where the system remains in the super-Alfvénic regime, ion escape is largely insensitive to the growing Bx component. This finding indicates that the magnetic barrier maintains its shielding efficiency under the super-Alfvénic regime.

  • YuBin He, QingChen Xu, YaJun Zhu, QinZeng Li, Cui Tu, Bing Cai, Wei Yuan, XinYing Wang, Feng Wei
    Earth and Planetary Physics. 2026, 10(3): 454-462.

    Atmospheric gravity waves (AGWs) observed by the All-Sky Airglow Imager (ASAI) require accurate identification for the study of atmospheric coupling mechanisms and space weather prediction. However, the traditional manual screening methods and existing machine learning approaches do not meet the demands of practical station monitoring, which has significantly impeded climatological statistical research based on AGWs. Therefore, a real-time detection framework for ground-based airglow gravity waves that integrates transfer learning with adaptive image preprocessing has been proposed. By employing wavelength-adaptive median filtering and multiscale fusion, the framework effectively suppresses stellar noise while preserving weak gravity wave features. The model utilizes an EfficientNet-B3 (convolutional neural network) backbone enhanced with a deformable convolutional layer, trained via a two-stage strategy: A frozen phase prevents overfitting by locking the lower level feature extractor, and a fine-tuning phase optimizes the deformable convolution through cosine annealing and layered optimization. This approach improves both feature transfer efficiency and gravity wave detection sensitivity. The resulting lightweight model achieves 91.2% accuracy with millisecond-level inference speed (23 ms per frame).

  • XiuYu Chen, ChangShun Liu, LiGang Li, DaLi Kong
    Earth and Planetary Physics. 2026, 10(3): 400-409.

    The influence of topography on rotating fluids may exceed conventional expectations. Here, we numerically examine viscous incompressible flows induced by sidewall topography, confined within a modified cylinder that rotates rapidly about its central vertical axis and precesses about another axis. To investigate specific flow patterns and boundary-interior correspondences, the cylindrical sidewall is modified by adding a vertical fin-type barrier extending all the way from the bottom to the top. The fully nonlinear Navier−Stokes equations with precessional forcing are solved in this modified cylindrical geometry, using a mixed finite element method. Numerical results show that the introduction of sidewall topography significantly alters the precessionally driven flow, particularly at high precession rates. While the primary dynamics associated with inertial wave propagation persist, rich vortical structures and turbulence emerge. Interestingly, the barrier does not invariably suppress the kinetic energy density; when its height approaches the cylinder radius under strong precession, the kinetic energy density even exceeds that of the cylinder case without a barrier. Such an anomalous enhancement of kinetic energy may offer new insights into how precession-driven flows over topography could contribute to sustaining long-lived planetary magnetic fields, including that of the early Moon.

  • LongFei Jia, Song Fu, YueQun Lou, TaiFeng Jin, XiaoTong Yun, ShaoTing Cheng, ShuYue Pang, XiangYuan Tong, Xin Ma, BinBin Ni
    Earth and Planetary Physics. 2026, 10(3): 385-399.

    Whistler-mode waves are ubiquitous in space environments and constitute a key mechanism for energy transfer and transformation. The near-1 Hz narrowband whistler-mode waves are commonly observed in lunar space. However, the generation mechanism of narrowband 1 Hz whistler-mode waves in the lunar environment, where no global magnetosphere or permanent bow shock exists, remains an open question. This study examines 1 Hz waves in the lunar environment by analyzing 12 years (2012–2023) of ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun) mission data (across an entire solar cycle). The spatial distribution, spectral characteristics, and polarization properties of these waves are investigated alongside their dependence on upstream solar wind parameters and lunar magnetic anomalies. The results reveal that 1 Hz waves are predominantly observed in the solar wind near the Moon, with clear dawn–dusk and north–south asymmetries. Wave amplitudes range from 0.03 to 1 nT, and approximately 90% of the events demonstrate no direct magnetic connectivity to the Moon. Importantly, wave amplitude shows a positive correlation with the solar wind dynamic pressure (Pdyn) and the total interplanetary magnetic field (Btotal) and an inverse correlation with the Alfvén Mach number (MA), underscoring the influence of upstream conditions on wave properties. Our findings reveal that the majority of waves occur on unconnected field lines, indicating a more complex generation and propagation scenario than previously assumed. Furthermore, wave properties are quantitatively shown to be strongly modulated by upstream solar wind conditions. These results provide critical statistical constraints for future studies of wave generation in the unique plasma environment of an unmagnetized body.