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30 March 2024, Volume 36 Issue 1 Previous Issue    Next Issue

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Progress in astronomical site testing at Dome A, Antarctica SHANG Zhaohui, HU Yi 2024, 36 (1):  1-11.  DOI: 10.13679/j.jdyj.20230085 Abstract ( 525 )   PDF (5369KB) ( 875 )   More and more observational evidence has demonstrated that the Dome A region where Kunlun Station is located has the best ground-based astronomical observation conditions in optical, infrared, and terahertz wave bands. It has excellent free-atmosphere seeing, extremely low precipitable water vapor, a very dark sky background at night, and months of continuous observation time during polar nights. Through a summary of work in the past seventeen years, this article focuses on the comprehensive site survey work at Dome A and presents the measurement results as well as the latest progress. References | Related Articles | Metrics

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Impact of polar particle precipitation on HF signal along Arctic shipping routes GE Shucan, XU Bin, LI Hailong, XU Tong, ZHU Mengyan, MENG Lin, WU Jian 2024, 36 (1):  12-25.  DOI: 10.13679/j.jdyj.20230068 Abstract ( 546 )   PDF (5099KB) ( 689 )   Arctic shipping routes connecting the Atlantic and Pacific Oceans through the Arctic Ocean, are rapidly evolving and will have profound implications for global geopolitics and the economy. Existing single-station HF signal communication systems are vulnerable to the challenging polar space environment, resulting in limited reliability and an inability to ensure safe navigation of vessels along the Arctic shipping routes. In response to the communication needs of the Arctic shipping routes, we established a theoretical framework to evaluate HF signal communication coverage based on deterministic models. Furthermore, the calculation methods for power in complex refractive index ray tracing have been focused on. We evaluated the communication effects of HF signal networking along the Arctic shipping routes, and investigated the impact of polar ionospheric disturbances, such as high-energy particle deposition, on HF signal propagation effects in polar region. This study provides a solid theoretical basis to assess the communication effectiveness of HF signal access networks and to optimize the design of station networks for communication along Arctic shipping routes. References | Related Articles | Metrics

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Comparison of polar region ionospheric NmF2 observations with the International Reference Ionosphere XU Sheng, LI Peihao, LIAO Xiaoqian, LIU Ruiyuan, CHEN Xiangcai 2024, 36 (1):  26-36.  DOI: 10.13679/j.jdyj.20220304 Abstract ( 507 )   PDF (1663KB) ( 573 )   This article systematically and quantitatively explores the applicability of the International Reference Ionosphere IRI-2016 model in polar regions, using observation data of the ionospheric F2-layer peak electron density (NmF2) acquired one solar cycle at three stations within the polar cusp region and the latitude of the aurora belt. The results showed good consistency between the IRI-2016 predictions and observation at the auroral latitude Tromsø Station, with relative errors less than 40% in most seasons. The accuracy of IRI-2016 prediction was marginally higher during solar maximum years than during solar minimum years at Tromsø, conversely it was higher during solar minimum years than during solar maximum years at the Zhongshan and Longyearbyen stations. At Zhongshan and Longyearbyen stations, the relative error is less than 20% in only a few months, more than 40% in most months, and is almost 100% in winter. Especially at Longyearbyen Station, the relative error is more than 100% in winter during solar maximum years. Overall consistency between observations and IRI-2016 prediction perform was lowest in winter, and highest in summer at all three stations. Plasma convection strongly influences NmF2 and particle precipitation in the polar regions, but the IRI-2016 model could not accurately reproduce these physical processes. References | Related Articles | Metrics

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Wavelet-based ULF pulsation indices and their application to geomagnetically conjugate ULF pulsation studies at high latitudes XU Zhonghua, C. Robert CLAUER, Michael D. HARTINGER, Hyomin KIM, Daniel R WEIMER 2024, 36 (1):  37-51.  DOI: 10.13679/j.jdyj.20230067 Abstract ( 367 )   PDF (10566KB) ( 138 )   Geomagnetic Ultra Low Frequency (ULF) are terrestrial manifestations of the propagation of very low frequency magnetic fluid waves in the magnetosphere, and it is critical to develop near real-time space weather products to monitor these geomagnetic disturbances. A wavelet-based index is described in this paper and applied to study geomagnetic ULF pulsations observed in Antarctica and their magnetically conjugate locations in West Greenland. Results showed that (1) the index is effective for identification of pulsation events in the Pc4–Pc5 frequency range, including transient events, and measures important characteristics of ULF pulsations in both the temporal and frequency domains. (2) Comparison between conjugate locations reveals the similarities and differences between ULF pulsations in northern and southern hemispheres during solstice conditions, when the largest asymmetries are expected. Results also showed that the geomagnetic pulsations at conjugate locations respond differently according to the Interplanetary Magnetic Field condition, magnetic field topology, magnetic latitude of the observation, and other conditions. The actual magnetospheric and ionospheric configurations and driving conditions in the case need to be further studied. References | Related Articles | Metrics

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An auroral substorm detection method based on cascaded cluster algorithms WANG Ping, HAN Bing, LI Jie, HU Zejun, SHANG Junliang , GE Daohui , YUAN Yu- zhuo 2024, 36 (1):  52-69.  DOI: 10.13679/j.jdyj.20230084 Abstract ( 428 )   PDF (13217KB) ( 284 )   The breakup of the auroral substorm is closely related to a sudden electromagnetic energy release during solar wind-magnetosphere coupling process. Understanding the mechanisms of substorm onset and expansion phase clarifies the interactions among interplanetary magnetic field, magnetosphere and ionosphere. Additionally, substorm research is essential to characterize the process of flux transport from the solar to earth, which is significant to the space weather forecast. Auroral images from the ultraviolet imager (UVI) aboard the Polar satellite are the main dataset containing records of auroral substorms, with clear depiction of complete auroral ovals and substorm bulge features. Existing substorm detection algorithms are mostly empirical, relying on manually designed features and rules. In this article, we propose a detection algorithm guided by cascaded cluster algorithms for automatic substorm detection. To avoid using handcraft features, spatiotemporal features of UVI image sequences are extracted using a three-dimensional convolution network with subspace clustering. Because of imaging angles differences between frames, UVI images coordinates are converted into MLAT-MLT (the magnetic latitude-magnetic local time) coordinate system for pixel alignment. Moreover, image level clustering is applied to reduce the UVI image noise by isolating the substorm bulge and discarding unimaged areas. Experimental results indicate that the proposed method achieves higher recall than existing standard methods. References | Related Articles | Metrics

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Observation of poleward boundary intensification events triggered by polar cap patches ZHAO Bianlong, XING Zanyang, ZHANG Qinghe, MA Yuzhang, WANG Yong, HU Zejun, ZHANG Jiaojiao, WANG Xiangyu, LU Sheng, ZHANG Duan 2024, 36 (1):  70-79.  DOI: 10.13679/j.jdyj.20240009 Abstract ( 505 )   PDF (10594KB) ( 351 )   Polar cap patches are common high-density irregularities in the polar cap ionosphere with electron densities of more than twice the background density. Poleward boundary intensifications (PBI) are auroral structures characterized by significantly enhanced brightness of the nightside auroral oval at its poleward boundary. Understanding PBI formation, evolution, and relationship with polar cap plasma is crucial to study the process of polar ionosphere–magnetosphere coupling. In this work, we analyzed the complete PBI generation process triggered by polar cap patches moving to the poleward boundary of the nightside auroral oval, using observational data from the all-sky auroral imager of the Arctic Yellow River Station, the European Incoherent Scatter (EISCAT) radars, and total electron content data from the GPS receivers. The results indicate that high-density plasma moved antisunward and reached the nightside poleward boundary of the auroral oval, markedly enhancing the local auroral intensity and triggering PBI events. When substorms induced a poleward expansion of the nightside auroral oval, EISCAT Svalbard 42 m radars observed high- density plasma structures with high electron and ion temperatures, as well as a decrease of the electron density peak height and an ion upflow, both explained by high-density plasma vertical transport and particle precipitation. This implies that plasma transported from the polar cap region to the nightside auroral oval effectively triggered PBI events that in turn, influenced the plasma characteristics. This analysis clarifies ionosphere–magnetosphere coupling processes in the nightside polar region. References | Related Articles | Metrics

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A paradigm shift in polar space physics Paul SONG 2024, 36 (1):  80-83.  DOI: 10.13679/j.jdyj.20230069 Abstract ( 444 )   PDF (266KB) ( 435 )   This article briefly describes a paradigm shift in high-latitude space physics—a scientific revolution. This paradigm shift is a theoretical framework change from the electrical engineering (EE) theory to the magnetohydrodynamic (MHD) theory. Currently, this paradigm shift has proceeded relatively slowly, it is expected to fundamentally change our understanding of the magnetosphere-ionosphere-thermosphere coupling within in the next 30–50 years. References | Related Articles | Metrics

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Progress of the Antarctic large field of view telescope WU Zhixu, CHEN Chao, JIANG Peng, CONG Jianan, YANG Hao, LI Zhengyang 2024, 36 (1):  84-98.  DOI: 10.13679/j.jdyj.20230077 Abstract ( 484 )   PDF (16036KB) ( 325 )   Astronomical observatory sites, in the extreme Antarctic environment, not only exhibit exceptional conditions for astronomical observations, but also present a notably high frequency of space debris transit. These characteristics provide high versatility for large field-of-view telescopes with diverse potential applications, such as astronomical observations, space debris management, and deep space exploration. To achieve scientific objectives while considering data requirements, China has deployed several large field of view telescopes with various optical systems in Antarctica. This review discusses key aspects of Antarctic large field of view observations. First, the Chinese Antarctic astronomical sites are described and the motivation for constructing multiple large field of view telescopes in Antarctica is given. Second, the types of optical systems currently used for Chinese Antarctic telescopes are detailed. Third, the expected scientific advances are listed. This review aims to demonstrate the usefulness of large field of view telescopes in the unique context of Antarctica. References | Related Articles | Metrics

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Critical control software technologies for Antarctic optical astronomical telescopes LI Xiaoyan, LI Yun, SUN Tianrui, YANG Shihai, DU Fujia, XU Lingzhe 2024, 36 (1):  99-111.  DOI: 10.13679/j.jdyj.20230079 Abstract ( 498 )   PDF (2864KB) ( 712 )   The control software of astronomical telescopes, running on their control computer, is an essential part of a telescope’s operational chain and the critical technological interface between users and telescopes. For users, the control software is an interactive interface that allows them to automate observations, control telescopes remotely via satellite communications, and conduct regular system fault diagnosis. For telescopes, the control software commands the pointing and precise tracking of celestial objects, calculates and compensates system errors, and optimizes operations to maximize image quality. Compared with their mid-latitude counterparts, optical telescopes operating in Antarctica face specific challenges requiring a specially designed control software. In this article, critical technologies and design principles specific to the Antarctic optical telescope control software are described: operating system, remote transfer of the telescope pointing error correction model, automatic observation interface, remote satellite communication, remote operation and maintenance, and on-site telescope status monitoring and fault diagnosis. Future development of relevant technologies is also discussed. This article aims to provide a technical reference for future development of Antarctic astronomical telescopes and control systems. References | Related Articles | Metrics