Abstract The explosive eruption of the Hunga‐Tonga volcano in southwest Pacific at 0415UT on 15 January 2022 triggered gigantic atmospheric disturbances with surface air pressure waves propagating around globe Lamb mode. In space, concentric traveling ionosphere (CTIDs) are also observed as a manifestation New Zealand ∼0500UT and Australia ∼0630UT. As soon reached central ∼0800UT, conjugate CTIDs appeared almost simultaneously northern hemispheres through interhemispheric coupling, much...

Abstract The FORMOSAT‐7/COSMIC‐2 (F7/C2) satellite mission was launched on 25 June 2019 with six low‐Earth‐orbit satellites and can provide thousands of daily radio occultation (RO) soundings in the low‐latitude midlatitude regions. This study shows preliminary results space weather data products based F7/C2 RO sounding: global ionospheric specification (GIS) electron density Ne‐aided Abel profiles. GIS is assimilation product Gauss‐Markov Kalman filter, assimilating ground‐based Global...

Abstract The Tonga volcano eruption of 15 January 2022 unleashed a variety atmospheric perturbations, coinciding with the recovery‐phase geomagnetic storm. ensuing thermospheric variations created rare display extreme poleward‐expanding conjugate plasma bubbles seen in rate total electron content index over 100–150°E, reaching ∼40°N geographic latitude. This is associated fluctuations FORMOSAT‐7/COSMIC‐2 (F7/C2) ion‐density measurements and spread‐F ionograms. Preceding to this, an unusually...

Abstract This study investigates new characteristics of ionospheric modulations driven by quasi‐6‐day wave (Q6DW) burst following a rare Antarctic sudden stratospheric warming (SSW) in September 2019. Local‐time and vertical variations the amplitude phase oscillation (Q6DO) ionosphere are examined using data assimilation analysis electron density from three‐dimensional Global Ionosphere Specification (GIS). The maximum amplitudes Q6DO located symmetrically ±20° off magnetic equator at ~12...

Abstract This study examines an unexpected and extreme positive ionospheric response to a minor magnetic storm on August 5, 2019 by using global ionosphere specification (GIS) 3D electron density profiles obtained assimilating radio occultation total content (TEC) measurements of the recently launched FORMOSAT‐7/COSMIC‐2 satellites, ground‐based navigation satellite system (GNSS) TEC. The results reveal ∼300% enhancement equatorial ionization anomaly (EIA) crests, appearing over 200–300 km...

Abstract Thanks to the work of a number scientists who made it known that severe space weather can cause extensive social and economic disruptions in modern high‐technology society. It is therefore important understand what determines severity whether be predicted. We present results obtained from analysis coronal mass ejections (CMEs), solar energetic particle (SEP) events, interplanetary magnetic field (IMF), CME‐magnetosphere coupling, geomagnetic storms associated with major events since...

Abstract This study presents the conjugate ionospheric disturbances triggered by 2011 Tohoku‐Oki reflected tsunami oceanic waves using ground‐based Global Navigation Satellite System (GNSS) total electron content (TEC) observations. We found that equatorward and westward propagating nighttime medium‐scale traveling (MSTIDs) occurred over Japan Australia simultaneously following Emperor Seamount Chain in northern hemisphere. The atmospheric gravity driven are hypothesized to be source trigger...

Abstract A unique phenomenon—A geomagnetically quiet time merging of Equatorial Ionization Anomaly (EIA) crests, leading to an X‐pattern (EIA‐X) around the magnetic equator—has been observed in night‐time ionospheric measurements by Global‐scale Observations Limb and Disk mission. The pattern is also reproduced model that assimilates slant Total Electron Content from Global Navigation Satellite System Constellation Observing for Meteorology, Ionosphere, Climate 2. free‐running whole...

FORMOSAT7-COSMIC2 Mission is consist of six satellites equipped with GNSS radio occultation (RO) payload, in-situ ion density and velocity meters (IVM), RF beacon transmitters at low latitudes. Signal-to-noise ratio (SNR) RO soundings provides observations irregularity altitudes, IVM measures fluctuations satellite altitude 550 km. Combining RO, IVM, ground-based receivers GNSS, it like an observation suite plasma irregularities that unprecedented number were not available previously. The...

This paper examines the application of hypothesis testing in machine learning model selection, focusing on distinguishing between statistically significant performance differences and random variations. We demonstrate how statistical tests such as t-tests ANOVA can be effectively combined with traditional evaluation metrics including accuracy, F1-score, precision to validate performance. integration, along cross-validation techniques, helps ensure generalization while mitigating overfitting risks.

The behavior of the low latitude ionosphere‐plasmasphere system in American‐Brazilian longitudes (30°W–120°W) three seasons at long deep solar minimum (2006–2010) is investigated using theoretical model SUPIM and FORMOSAT‐3/COSMIC electron density GIM‐TEC data. data reveal some new aspects primarily for EUV fluxes. ionosphere develops as a thin layer morning though becomes nearly strong that normal around diurnal maximum (14 LT). However, after sunset decays rapidly to become an extremely...

This paper provides an overview of the contributions space-based global navigation satellite system (GNSS) radio occultation (RO) measurements from FORMOSAT-7/COSMIC2 (F7/C2) mission in advancing our understanding ionospheric plasma physics purview space weather. The positioning (GPS) experiment (GOX) onboard FORMOSAT-3/COSMIC (F3/C), with more than four and half million RO soundings during April 2006–May 2020, offered a unique three-dimensional (3D) perspective to examine electron density...

Using the continuous Dst data available since 1957 and H component for Carrington space weather event of 1859, paper shows that mean value during main phase geomagnetic storms, called DstMP, is a unique parameter can indicate severity weather. All storms having high DstMP (≤−250 nT), which corresponds to amount energy input in magnetosphere–ionosphere system short duration, are found associated with severe events caused all known electric power outages telegraph failures.

Abstract Using the global ionospheric map of total electron content in 2002–2009, this paper investigates anomalous, midlatitude density enhancement (MEDE) bounded by a tropical trough and usual at all times (24 h) day for first time. The diurnal, seasonal, longitudinal variations occurrence strength MEDE are studied solar maximum (2002) long deep minimum (2009), latitude‐longitude dependence is examined using data 2002–2009. results show that occurs though pronounced night (2200–0400 LT),...

[1] This paper derives the theoretical relationship between vertical integrated intensity of OI 135.6 nm oxygen emission with electron content (IEC) from 150 to 800 km altitude as well F layer peak density (NmF2). Local time, seasonal, and solar cycle dependence is investigated, it proposed a conversion factor retrieve IEC NmF2 values airglow measurements. The errors associated estimation using derived are demonstrated for different local times activity. compared that calculated measurements...

Abstract All‐sky camera observations carried out over Taiwan showed intense equatorial plasma bubbles (EPBs) in 630.0 nm airglow images on consecutive nights of 13–16 March 2015 but were absent the following night 17 when St. Patrick's Day magnetic storm occurred. Rate total electron content (TEC) index by using Global Positioning System (GPS) network data also confirmed absence irregularities March. The results, however, revealed strong Indian sector same night. Flux tube integrated...

Abstract In this study, Global Ionosphere Specification (GIS) based on Gauss‐Markov Kalman filter assimilation of slant total electron content observed from ground‐based global positioning system receivers and space‐based radio occultation instrumentations is applied to investigate the ionospheric day‐to‐day tidal variability during 2009 stratospheric sudden warming (SSW) period. Including improved daily three‐dimensional density distribution GIS enables us retrieve solar solution by using...

Abstract This paper reports the results of space‐based imaging nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) in 630.0 nm emission by Imager Sprites and Upper Atmospheric Lightnings (ISUAL), on board FORMOSAT‐2 satellite. The limb integrated measurements, after removing background, reveal multiple bands intensity perturbation when projected to a horizontal plane corresponding altitude peak emission, with distinct southwest northeast orientation Southern Hemisphere....

Abstract An annular solar eclipse swept over Taiwan in the early morning on 21 May 2012. This provides an excellent opportunity to study ionospheric response mainly due photochemical effects. Local ground‐based Global Positioning System receivers, ionosonde, high frequency‐continue wave Doppler sounding systems, and very low frequency receivers are used observe signatures. These multiinstrument observations show that extreme total electron content (TEC) depression lags maximum obscuration by...

Abstract FORMOSAT-3/COSMIC (F3/C) constellation of six micro-satellites was launched into the circular low-earth orbit at 800 km altitude with a 72-degree inclination angle on 15 April 2006, uniformly monitoring ionosphere by GPS (Global Positioning System) Radio Occultation (RO). Each F3/C satellite is equipped TIP (Tiny Ionospheric Photometer) observing 135.6 nm emissions and TBB (Tri-Band Beacon) for conducting ionospheric tomography. More than 2000 RO profiles per day first time allows...

Abstract Flux tube integrated Rayleigh‐Taylor instability growth rates computed by using the results of ionosphere data assimilation are used for first time to investigate global plasma bubble occurrence. The study is carried out assimilating total electron content measurements ground‐based Global Positioning System (GPS) receivers into thermosphere electrodynamic general circulation model, and calculated standalone model run without (control run) as well prior (or forecast) state output...

A computer program is developed to automatically identify the geomagnetic storms in Dst index by applying four selection criteria that minimize non-storm-like fluctuations. The used Kyoto and USGS 50 years (1958–2007). identified (DstMin ≤ −50 nT) are investigate their seasonal variations. It found overall variations of storm parameters such as occurrence, average intensity (average DstMin) strength ⟨DstMP⟩) both versions exhibit clear semiannual with equinoctial maxima solstice minima;...