Article
Astronomy & Astrophysics
L. M. Bjoland, Y. Ogawa, U. P. Lovhaug, D. A. Lorentzen, S. M. Hatch, K. Oksavik
Summary: This paper discusses electron density depletion regions observed with the EISCAT Svalbard Radar, focusing on their dependencies on diurnal and seasonal variations and solar activity. The findings show that the depletion regions are clearest during equinox and winter with moderate/high solar activity. Additionally, an enhancement in ion temperature often accompanies the electron density depletion region.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Nina Kristine Eriksen, Dag A. Lorentzen, Kjellmar Oksavik, Lisa Baddeley, Keisuke Hosokawa, Kazuo Shiokawa, Emma Bland, Larry Paxton, Yongliang Zhang, Kathryn Mcwilliams, Tim Yeoman, David R. Themens
Summary: Ionospheric convection patterns from the Super Dual Auroral Radar Network were used to track the trajectories, transit times, and decay rates of polar cap patches. The study found that polar cap patches have variable plasma decay rates at different stages of their lifetime, and stagnation is considered a major determinant for complete decay.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Geosciences, Multidisciplinary
Duan Zhang, Qing-He Zhang, Kjellmar Oksavik, Tong Xu, Zan-Yang Xing, L. R. Lyons, De-Sheng Han, Hong-Bo Zhang, Yu-Zhang Ma, Ze-Jun Hu, Jian-Jun Liu, Yong Wang, Xiang-Yu Wang
Summary: Throat auroras and polar cap patches are common phenomena in the polar ionosphere resulting from magnetosphere-ionosphere coupling. Observations during periods of radial interplanetary magnetic field (IMF) showed that throat auroras linked to poleward moving ionization patches. Throat auroras were produced by soft-electron precipitation associated with dayside magnetic reconnection and correlated with dayside reconnection events. Dense plasma from lower latitudes was transported poleward to form patches, which moved anti-sunward due to the E x B drift.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Physics, Multidisciplinary
Dion Noordhuis, Anirudh Prabhu, Samuel J. Witte, Alexander Y. Chen, Fabio Cruz, Christoph Weniger
Summary: This Letter develops a comprehensive framework to model the production of axions and their transition into photons in neutron star magnetospheres. Using observations of nearby pulsars, constraints on the axion-photon coupling are derived. The presented limits are the strongest to date for a specific range of axion masses and do not rely on the assumption that axions are dark matter.
PHYSICAL REVIEW LETTERS
(2023)
Article
Engineering, Marine
Hairui Zhao, Yao Shi, Guang Pan, Qiaogao Huang
Summary: A numerical model and experimental research were conducted to study the high-speed entry of vehicles. The results showed that the axial load and impact load can be reduced by increasing the inlet velocity and using buffer caps.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Meteorology & Atmospheric Sciences
Christopher J. Cardinale, Brian E. J. Rose, Andrea L. Lang, Aaron Donohoe
Summary: The study examines the vertical structure of moist static energy flux into polar regions using NASA-MERRA-2 reanalysis data from 1980 to 2016. It finds a bimodal distribution of climatological flux in the middle to lower troposphere and middle to upper stratosphere, with a near-zero flux at the tropopause. Especially at 70 degrees N, the contribution of F-strat to F-wall is significant during winter, impacting the variability of F-wall.
JOURNAL OF CLIMATE
(2021)
Article
Geochemistry & Geophysics
Haifeng Xiao, Alexander Stark, Frederic Schmidt, Jingyan Hao, Shu Su, Gregor Steinbrugge, Jurgen Oberst
Summary: The seasonal deposition and sublimation of CO2 play a crucial role in the volatile cycle on Mars. By using co-registration strategies, researchers obtained spatio-temporal variations in snow/ice levels on the Seasonal South Polar Cap (SSPC), with the highest levels observed over the Residual South Polar Cap. The study also found that the snow/ice levels in Martian Year 25 were typically around 0.5 meters higher than in Martian Year 24, with an estimated peak volume of approximately 9.4 x 10(12) m(3). Additionally, the study revealed that there is more snowfall-like precipitation at the Residual South Polar Cap and its surroundings compared to other regions on Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Environmental Sciences
Lei Zhang, Yang Lu, Jinhai Zhang
Summary: This study examines the polygonal terrains on a Martian southern polar cap and proposes a possible formation mechanism. Through quantitative analysis of the polygonal terrains, including area, orientation, and edge density, the study identifies different elevation-related subregions and suggests a potential uplift or subsidence on Mars. The findings contribute to a better understanding of ancient and/or present climates on the planet.
Editorial Material
Geosciences, Multidisciplinary
Dustin M. Schroeder, Gregor Steinbrugge
Summary: Bright radar reflections beneath Mars' south polar ice cap initially suggested the presence of liquid water. However, recent research indicates that similar reflections are widespread and other materials may also produce the bright signals, raising the possibility of alternative sources for the observations.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Engineering, Marine
Yao Hong, Zhaoxin Gong, Hua Liu
Summary: The present study investigates the dynamics of splash curtain by vertical water entry of a sphere under different atmospheric densities. A simplified model is proposed to analyze the experimental results, showing that the size of splash and surface seal time increase as the atmospheric density decreases. The model focuses on the rounded rim at the tip of the splash, reducing the complex splash evolution to a ballistics problem considering pressure drop and surface tension. The results reveal that the trajectory of the rounded rim is approximately a circular arc when pressure drop force dominates, but becomes a spiral as the atmospheric density decreases and the effect of pressure drop force weakens. Under extreme conditions, the evolution of splash is extended by surface tension, resulting in the disappearance of surface seal.
Article
Physics, Fluids & Plasmas
Pengfei Zhang, Xin Liu, Mengjiao Lin, Jia Zhang
Summary: This research introduces a high-energy pulsed plasma jet that can generate highly dynamic and steep plasma gradients. By modulating the dynamics of the plasma sheath electron density, the high-speed vehicle can achieve stealth. The characteristics of the plasma were extensively diagnosed through various measurements and observations. The analysis of high-energy pulsed plasma jets provides a framework for future research on stealth technology in high-speed vehicles.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Applied
Eungkyun Kim, Zexuan Zhang, Jimy Encomendero, Jashan Singhal, Kazuki Nomoto, Austin Hickman, Cheng Wang, Patrick Fay, Masato Toita, Debdeep Jena, Huili Grace Xing
Summary: Recent observations of high density polarization-induced electron gases in ultra-thin N-polar GaN layers on single-crystal AlN have allowed for the development of N-polar high electron mobility transistors (HEMTs) on AlN. These devices can take advantage of AlN's thermal and power handling capabilities, while also benefitting from N-polar structures like a strong back barrier. Experimental demonstrations of N-polar GaN/AlGaN/AlN HEMTs on single-crystal AlN substrates have shown promising performance, paving the way for RF electronics with excellent thermal management based on N-polar single-crystal AlN.
APPLIED PHYSICS LETTERS
(2023)
Article
Astronomy & Astrophysics
Peter Stauning
Summary: This study introduces different versions of the standard polar cap (PC) indices, as well as derivation procedures developed to generate alternative PCS index values based on Dome Concordia (Dome-C) data. The assessments of the new PCS index have shown its unprecedented high relevance. Some methods used in this study deviate from the corresponding features considered inadequate by the International Association for Geomagnetism and Aeronomy-endorsed PC index derivation methods.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Chemistry, Physical
Antonio Castro, Sebastian Calderon, Luis Marques
Summary: Zn:ZnO nanostructures have promising applications in fields such as food packaging due to their ability to scavenge oxygen. However, the mechanisms involved in the growth of ZnO on Zn are not fully understood. In this study, ab initio DFT calculations were used to investigate the adsorption properties of oxygen molecules on Zn:ZnO heterostructures. The results suggest that the charge transfer mechanism can be promoted by electronic doping and the presence of dangling bonds on ZnO surfaces.
Article
Food Science & Technology
Roberta Foligni, Cinzia Mannozzi, Lama Ismaiel, Filippo Capelli, Romolo Laurita, Silvia Tappi, Marco Dalla Rosa, Massimo Mozzon
Summary: Cold atmospheric plasma (CAP) is a non-thermal technology that can be used for food decontamination by producing reactive species (RS), but it may also promote food lipid oxidation. This study evaluated the oxidation degree of pistachio kernels after CAP treatment and found that the plasma treatment did not significantly affect the fatty acid composition, but led to an unexpected increase in γ-tocopherol content.
Article
Astronomy & Astrophysics
G. Branduardi-Raymont, M. Berthomier, Y. V. Bogdanova, J. A. Carter, M. Collier, A. Dimmock, M. Dunlop, R. C. Fear, C. Forsyth, B. Hubert, E. A. Kronberg, K. M. Laundal, M. Lester, S. Milan, K. Oksavik, N. Ostgaard, M. Palmroth, F. Plaschke, F. S. Porter, I. J. Rae, A. Read, A. A. Samsonov, S. Sembay, Y. Shprits, D. G. Sibeck, B. Walsh, M. Yamauchi
Summary: The flow of solar wind energy through Earth's magnetosphere and how it is converted and distributed is a key question to be addressed. Understanding geomagnetic storms and substorms is important not only for scientific curiosity, but also for dealing with the practical problem of space weather, which can impact technological systems and human health. While significant knowledge has been gained in the past decades, the infancy of space weather forecasting shows that there is still much to learn. Novel global approaches, such as tomographic imaging missions, are being developed to further advance our understanding of solar-terrestrial interactions.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Beatriz Sanchez-Cano, Mark Lester, Marco Cartacci, Roberto Orosei, Olivier Witasse, Pierre-Louis Blelly, Wlodek Kofman
Summary: This study investigates the behavior of Mars' ionosphere during two consecutive solar minima (23/24 and 24/25) using the same dataset. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) is used to study the total electron content and the variability of the electron density profiles. The study confirms that the empirical model equations for the Martian ionosphere derived for the solar minimum 23/24 are also valid and accurate for the solar minimum 24/25.
Article
Astronomy & Astrophysics
Beatriz Sanchez-Cano, Mark Lester, David J. Andrews, Hermann Opgenoorth, Robert Lillis, Francois Leblanc, Christopher M. Fowler, Xiaohua Fang, Oleg Vaisberg, Majd Mayyasi, Mika Holmberg, Jingnan Guo, Maria Hamrin, Christian Mazelle, Kerstin Peter, Martin Patzold, Katerina Stergiopoulou, Charlotte Goetz, Vladimir Nikolaevich Ermakov, Sergei Shuvalov, James A. Wild, Pierre-Louis Blelly, Michael Mendillo, Cesar Bertucci, Marco Cartacci, Roberto Orosei, Feng Chu, Andrew J. Kopf, Zachary Girazian, Michael T. Roman
Summary: This White Paper discusses key scientific questions about the dynamics of the Martian plasma system and how they could be addressed through coordinated multi-point missions. It presents specific scientific objectives and proposes two mission concepts based on coordinated multi-point science to focus on understanding and solving current science gaps.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Mark Lester, Beatriz Sanchez-Cano, Daniel Potts, Rob Lillis, Marco Cartacci, Fabrizio Bernardini, Roberto Orosei, Matthew Perry, Nathaniel Putzig, Bruce Campbell, Pierre-Louis Blelly, Steve Milan, Hermann Opgenoorth, Olivier Witasse, Elena M. M. Redrojo, Aaron Russell
Summary: This study presents the first long-term characterization of ionization layers in the lower ionosphere of Mars based on radar echo blackouts observed from 2006 to 2017. The analysis reveals that blackout occurrence is correlated with solar cycle and there is no apparent relationship with crustal magnetic fields. Higher frequency radars are more susceptible to blackouts. Additionally, the study finds that enhanced solar energetic particles at higher energy end are responsible for the blackouts.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Katerina Stergiopoulou, David J. Andrews, Niklas J. T. Edberg, Jasper Halekas, Mark Lester, Beatriz Sanchez-Cano, Andrew P. Dimmock, Jacob R. Gruesbeck
Summary: This study investigates the effects of upstream solar wind conditions on the Martian induced magnetosphere and upper ionosphere. By analyzing data from Mars Express and the MAVEN mission, it is found that the ratio of induced magnetic field magnitude to interplanetary magnetic field magnitude in the induced magnetosphere generally decreases with increased dynamic pressure.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Duan Zhang, Qing-He Zhang, Y. -Z. Ma, Kjellmar Oksavik, L. R. Lyons, Zan-Yang Xing, Marc Hairston, Z. -X. Deng, J. -J. Liu
Summary: This study analyzes the distribution of cold patches and hot patches using satellite data and investigates their dependence on local plasma transport and soft-electron precipitation. The results show that cold and hot patches have different distribution patterns under different interplanetary magnetic field orientations and ionospheric convection geometries.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Andres Spicher, James LaBelle, John W. Bonnell, Roger Roglans, Chrystal Moser, Stephen A. Fuselier, Scott Bounds, Lasse B. N. Clausen, Francesca Di Mare, Connor A. Feltman, Yaqi Jin, Craig Kletzing, Wojciech J. Miloch, Joran I. Moen, Kjellmar Oksavik, Rhyan Sawyer, Toru Takahashi, Tim K. Yeoman
Summary: This study investigates the nature of small-scale irregularities observed in the cusp by TRICE-2. The results show that decameter-scale irregularities follow the E x B velocity, are nondispersive, and are prominent outside regions with strong precipitation.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Review
Astronomy & Astrophysics
Glyn Collinson, Alex Glocer, Rob Pfaff, Aroh Barjatya, Scott Bissett, Kolbjorn Blix, Aaron Breneman, Jim Clemmons, Francis Eparvier, Ted Gass, Robert Michell, David Mitchell, Suzie Imber, Ahmed Ghalib, Hassanali Akbari, Glen Ansted, Lisa Baddeley, Havard Bahr, Gary Bain, Brian Bonsteel, Henry Borgen, Daniel Bowden, Dave Bowker, Tim Cameron, Meredith Campbell, Philip Cathell, Dennis Chornay, Robert Clayton, Larry Conser, Lance Davis, Sean Donohue, Leif Jonny Eilertsen, Charles Etheridge, Nathan Graves, Ingemar Haggstrom, Preben Hanssen, Herbert Haugh, Espen Helgesen, Jordan Henderson, Kim Roar Herseth, John Hickman, Kent-Goran Jensen, Travis Jester, Eric Johnson, Hunter Johnson, Andrew Kavanagh, Max King, David Knight, Russell Laman, Trevor Lankford, Rolf Lien, Mark Lester, Gordon Marsh, Steve Martin, Norman Morris, Long Nguyen, Richard Nelson, Wale Ogundere, Karl Henning Osbakk, Dave Page, Joe Polidan, Devon Raley, Richard Raymond, Ellen Robertson, Giovanni Rosanova, Traci Rosnack, Belinda Serabian, Roger Simonsen, Jan Arne Soreng, Jostein Sveen, Diana Swanson, Robert Swift, Paulo Uribe, Henry Valentine, Frank Waters, Libby West, Tim Wilson
Summary: NASA's Endurance sounding rocket will carry out a mission to measure the weak ambipolar electric field generated by Earth's ionosphere, providing key data for a better understanding of Earth's atmosphere.
SPACE SCIENCE REVIEWS
(2022)
Article
Geosciences, Multidisciplinary
E. C. M. Dawkins, G. Stober, D. Janches, J. D. Carrillo-Sanchez, R. S. Lieberman, C. Jacobi, T. Moffat-Griffin, N. J. Mitchell, N. Cobbett, P. P. Batista, V. F. Andrioli, R. A. Buriti, D. J. Murphy, J. Kero, N. Gulbrandsen, M. Tsutsumi, A. Kozlovsky, J. H. Kim, C. Lee, M. Lester
Summary: The mesosphere/lower thermosphere (MLT) region serves as a significant boundary between Earth's atmosphere and space, and it can be a sensitive indicator for anthropogenic climate change. Previous studies have shown that the MLT is cooling and contracting due to increasing greenhouse gas emissions. However, trend analyses are influenced by factors such as time periods, measurement types, and methodologies used.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Duan Zhang, Qing-He Zhang, Kjellmar Oksavik, Tong Xu, Zan-Yang Xing, L. R. Lyons, De-Sheng Han, Hong-Bo Zhang, Yu-Zhang Ma, Ze-Jun Hu, Jian-Jun Liu, Yong Wang, Xiang-Yu Wang
Summary: Throat auroras and polar cap patches are common phenomena in the polar ionosphere resulting from magnetosphere-ionosphere coupling. Observations during periods of radial interplanetary magnetic field (IMF) showed that throat auroras linked to poleward moving ionization patches. Throat auroras were produced by soft-electron precipitation associated with dayside magnetic reconnection and correlated with dayside reconnection events. Dense plasma from lower latitudes was transported poleward to form patches, which moved anti-sunward due to the E x B drift.
GEOPHYSICAL RESEARCH LETTERS
(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
Yu-Zhang Ma, Qing-He Zhang, Larry Lyons, Kjellmar Oksavik, Zan-Yang Xing, Marc Hairston, Balan Nanan, Ze-Jun Hu, Yong Wang, Si-Han Zhao
Summary: The plasma characteristics and evolution of hot dense plasma and classical polar cap patches are investigated based on combined observations. Both show enhanced F region density, but the hot dense plasma is associated with higher electron temperature and enhanced E region electron density caused by particle precipitation. The hot dense plasma is closer to the cusp region and associated with strong auroral emissions compared to the cold patch. The evolution process of hot/cold dense plasma is discussed based on the joint observations.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nina Kristine Eriksen, Dag A. Lorentzen, Kjellmar Oksavik, Lisa Baddeley, Keisuke Hosokawa, Kazuo Shiokawa, Emma Bland, Larry Paxton, Yongliang Zhang, Kathryn Mcwilliams, Tim Yeoman, David R. Themens
Summary: Ionospheric convection patterns from the Super Dual Auroral Radar Network were used to track the trajectories, transit times, and decay rates of polar cap patches. The study found that polar cap patches have variable plasma decay rates at different stages of their lifetime, and stagnation is considered a major determinant for complete decay.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Meteorology & Atmospheric Sciences
Gunter Stober, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Ales Kuchar, Christoph Jacobi, Chris Meek, Diego Janches, Guiping Liu, Masaki Tsutsumi, Njal Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell
Summary: Meteor radars are widely used for studying atmospheric dynamics, especially in the altitude range of 70 to 110 km. In this study, potential biases in vertical wind estimation intrinsic to the radar observation geometry and scattering mechanism are investigated. A mathematical debiasing process using a spatiotemporal Laplace filter is introduced to mitigate these biases. The results show good agreement between the vertical winds obtained from this retrieval algorithm and model data, and the first observational indications of a forward scatter wind bias are presented. A new retrieval algorithm called 3DVAR+DIV is introduced to derive vertical winds and wind variability from multistatic meteor radar networks.
ATMOSPHERIC MEASUREMENT TECHNIQUES
(2022)