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1. A Machine Learning Algorithm to Detect and Analyze Meteor Echoes Observed by the Jicamarca Radar

   https://doi.org/10.3390/rs15164051  

   Li, Yanlin; Galindo, Freddy; Urbina, Julio; Zhou, Qihou; Huang, Tai-Yin (August 2023, Remote Sensing)

   We present a machine-learning approach to detect and analyze meteor echoes (MADAME), which is a radar data processing workflow featuring advanced machine-learning techniques using both supervised and unsupervised learning. Our results demonstrate that YOLOv4, a convolutional neural network (CNN)-based one-stage object detection model, performs remarkably well in detecting and identifying meteor head and trail echoes within processed radar signals. The detector can identify more than 80 echoes per minute in the testing data obtained from the Jicamarca high power large aperture (HPLA) radar. MADAME is also capable of autonomously processing data in an interferometer mode, as well as determining the target’s radiant source and vector velocity. In the testing data, the Eta Aquarids meteor shower could be clearly identified from the meteor radiant source distribution analyzed automatically by MADAME, thereby demonstrating the proposed algorithm’s functionality. In addition, MADAME found that about 50 percent of the meteors were traveling in inclined and near-inclined circular orbits. Furthermore, meteor head echoes with a trail are more likely to originate from shower meteor sources. Our results highlight the capability of advanced machine-learning techniques in radar signal processing, providing an efficient and powerful tool to facilitate future and new meteor research. 

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2. Solar Flare Effects on 150‐km Echoes Observed Over Jicamarca: WACCM‐X Simulations

   https://doi.org/10.1029/2019GL084790  

   Pedatella, N. M.; Chau, J. L.; Vierinen, J.; Qian, L.; Reyes, P.; Kudeki, E.; Lehmacher, G.; Oppenheim, M. (October 2019, Geophysical Research Letters)

   Abstract Jicamarca Radio Observatory observations and Whole Atmosphere Community Climate Model with thermosphere‐ionosphere eXtension (WACCM‐X) simulations are used to investigate the effects of the 7 September 2005 X‐17 solar flare on 150‐km echoes, electron densities, and vertical plasma drifts. The solar flare produces a remarkably similar response in the observed 150‐km echoes and simulated electron densities. The results provide additional evidence of the relationship between the background electron density and the layering structure that is seen in 150‐km echoes. The simulations also capture a similar rapid decrease in vertical plasma drift velocity that is seen in the observations. The simulated change in vertical plasma drift is, however, weaker than the observed decrease at the longitude of Jicamarca, though it is stronger east of Jicamarca. The effect of the solar flare on the vertical plasma drifts is primarily attributed to changes in conductivity due to the enhanced ionization during the solar flare. 

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3. Simulating neutrino echoes induced by secret neutrino interactions

   https://doi.org/10.1088/1475-7516/2023/02/042  

   Carpio, Jose Alonso; Murase, Kohta (February 2023, Journal of Cosmology and Astroparticle Physics)

   Abstract New neutrino interactions beyond the Standard Model (BSM) have been of much interest in not only particle physics but also cosmology and astroparticle physics. We numerically investigate the time delay distribution of astrophysical neutrinos that interact with the cosmic neutrino background. Using the Monte Carlo method, we develop a framework that enables us to simulate the time-dependent energy spectra of high-energy neutrinos that experience even multiple scatterings en route and to handle the sharp increase in the cross section at the resonance energy. As an example, we focus on the case of secret neutrino interactions with a scalar mediator. While we find the excellent agreement between analytical and simulation results for small optical depths, our simulations enable us to study optically thick cases that are not described by the simplest analytic estimates. Our simulations are used to understand effects of cosmological redshifts, neutrino spectra and flavors. The developments will be useful for probing BSM neutrino interactions with not only current neutrino detectors such as IceCube and Super-Kamiokande but also future neutrino detectors such as IceCube-Gen2 and Hyper-Kamiokande. 

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4. The surface climatology of the Ross Ice Shelf Antarctica: SURFACE CLIMATOLOGY OF THE RIS ANTARCTICA

   https://doi.org/10.1002/joc.4681  

   Costanza, Carol A.; Lazzara, Matthew A.; Keller, Linda M.; Cassano, John J. (December 2016, International Journal of Climatology)
5. Diagnostics of Ionospheric Field Aligned Irregularities (FAIs) Using "Patchy" Specularly Reflected (SR) Whistler-Mode Echoes Observed on IMAGE

   Reddy, Amani; Sonwalkar, Vikas S (December 2022, AGU Fall Meeting 2022)