Results 71 to 80 of about 5,624 (239)

Food security dynamics in Oman: VECM approach [PDF]

, 2020
The paper examines the determinants of food security in Oman during the period 1980-2019. It investigates the influence of population growth rate and GDP per capita on food security.
Devesh, Sonal, M. Asrul Affendi, Abdullah   +1 more
core  

Freshly Generated Super Sunrise Plasma Bubbles During the Geomagnetic Storm on November 5–6, 2023

Space Weather, Volume 24, Issue 1, January 2026.
Abstract During the geomagnetic storm on November 5–6, 2023, freshly generated super sunrise equatorial plasma bubbles (EPBs) and associated irregularities over the 80°–140°E sector were observed combining ground‐based and space observations from GNSS, ionosondes, HF Doppler records, and several satellite missions (COSMIC2, Swarm, and DMSP).
Ke Li, Donghe Zhang, Yaoyu Tian, Yi Zeng, Guanglin Yang, Xiukuan Zhao, Guozhu Li, Yongqiang Hao   +7 more
wiley   +1 more source

Ionogram scaling using Hidden Markov Models [PDF]

2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
In this paper, a novel method for electron density reconstruction using ionosonde data is proposed. Proposed technique uses Hidden Markov Models for extracting echoes that provides valuable information about electron density distribution in order to provide input to a model based optimization technique that reconstructs the electron density ...
Gök, Gökhan, Alp, Y. K., Arıkan, Orhan, Arikan, F.   +3 more
openaire   +2 more sources

Evidence and Causes of an Unusual Super Plasma Bubble Occurrence During Weak Geomagnetic Conditions Over Europe

Space Weather, Volume 24, Issue 1, January 2026.
Abstract Using data from a cluster of ground‐based global navigation satellite system, we observed spatially extended enhanced ROTI over the European longitudes during a weak geomagnetic storm (Dst ≈ ${\approx} $ −50 nT) on 4 November 2023. The enhanced ROTI is extended over an extensive geographical latitudinal range of 46°N.
Chandan Kapil, Mani Sivakandan, Jorge Chau, Gopi K. Seemala, David Altadill   +4 more
wiley   +1 more source

Forecasting Equatorial Plasma Bubbles From Precursor TEC Signatures Observed by C/NOFS

Space Weather, Volume 24, Issue 1, January 2026.
Abstract This study investigates the potential of localized total electron content (TEC) perturbation measurements, possibly associated with bottomside upwelling of the F‐layer, as precursors for forecasting ionospheric plasma irregularities, particularly the equatorial plasma bubbles (EPBs).
S. K. Das, C. Stolle, Y. Yamazaki, T. Yokoyama, M. Yamamoto, S. Perwitasari   +5 more
wiley   +1 more source

Acquirement and analysis of Doppler ionograms with high accuracy in the ionogram mode from Digisonde 256 [PDF]

Radio Science, 2004
The Doppler frequency shift of the radio echo reflected from the ionosphere is an important characteristic to measure ionospheric movements. Generally, for the Digisonde 256 digital ionosonde, a Doppler frequency shift with high resolution can be obtained in the drift mode. In this mode, the height profile of ionospheric disturbances cannot be acquired
Zhigang Yuan, Baiqi Ning, Weixing Wan, Hong Yuan   +3 more
openaire   +1 more source

Laboratory Cultures [PDF]

, 2005
Cet essai se sert des cultures visuelles et matérielles de deux laboratoires afin d'engager une discussion historiographique sur ce que signifie écrire l’histoire de la science et de la technologie au Canada. Il emploie un sujet potentiellement familier,
Jones-Imhotep, Edward
core   +1 more source

NOIRE-Net–a convolutional neural network for automatic classification and scaling of high-latitude ionograms

Frontiers in Astronomy and Space Sciences
Millions of ionograms are acquired annually to monitor the ionosphere. The accumulated data contain untapped information from a range of locations, multiple solar cycles, and various geomagnetic conditions.
Andreas Kvammen, Juha Vierinen, Juha Vierinen, Devin Huyghebaert, Theresa Rexer, Andres Spicher, Björn Gustavsson, Jens Floberg   +7 more
doaj   +1 more source

Upwelling Metallic Ions Producing Valley Region Irregularities Over Low Latitude During the 2025 New Year Magnetic Storm

Geophysical Research Letters, Volume 52, Issue 24, 28 December 2025.
Abstract Valley region irregularities (VRIs) have been previously investigated using radar, ionosonde, and rocket‐borne in situ observations. In this paper, based on a joint observational experiment by lidar and radars performed in Hainan, China, we report a case of low‐latitude VRIs generated in association with uplifted metallic ions for the first ...
Jing Jiao, Wenjie Sun, Guozhu Li, Yajun Zhu, Biqiang Zhao, Guotao Yang, Tatsuhiro Yokoyama, Septi Perwitasari, Lianhuan Hu, Jianfei Liu, Haiyong Xie, Zhaoguo Huang, Xiaofei Wu, Chunxiao Yan   +13 more
wiley   +1 more source

HF radio path modeling by waveguide approach

Solar-Terrestrial Physics
We present a scheme for modeling HF radio signal characteristics along paths of different lengths, which is based on the waveguide approach — the normal mode method.
Ponomarchuk S. N., Kurkin V. I., Ilyin N. V., Penzin M. S.   +3 more
doaj   +1 more source