Spread F occurrence and drift under the crest of the equatorial ionization anomaly from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data

Authors
Chum, Jaroslav; Liu, Jann Yenq; Chen, Shih Ping; Cabrera, Miguel Angel; Laštovička, Jan; Baše, Jiří; Burešová, Dalia; Fišer, Jiří; Hruška, František; Ezquer, Rodolfo Gerardo
Publication Year
2016
Language
English
Format
article
Status
Published version
Description
A relatively new method based on measurements by multipoint continuous Doppler sounding is applied to study the occurrence rate, propagation velocities, and directions of spread F structures over Tucumán, Northern Argentina, and Taiwan, both of which were under the crest of the equatorial ionization anomaly in 2014. In addition, spread F is studied globally over the same time period from the S4 scintillation index measured onboard FORMOSAT-3/COSMIC (F3/C) satellite. It is shown that the continuous Doppler sounding gives results that are consistent with S4 data and with previous optical, global positioning system (GPS), and satellite measurements. Most of the spread F events were observed from September to March, i.e., during the local summer half of the year in Tucumán, whereas in Taiwan, the highest occurrence rate was observed around equinoxes. The occurrence rate in Tucumán was about four times higher than that in Taiwan. The propagation velocities and directions were estimated from the Doppler shift spectrograms. The spread structures related to spread F propagated roughly eastward at velocities from ~70 to ~200 m s-1 during nighttime hours. The mean observed horizontal velocity was 140 m s-1 over Tucumán and 107 m s-1 over Taiwan. The local times at which the highest velocities were observed roughly correspond to local times with highest values of scintillation index S4, at ~20 to 23 LT. In addition, a comparison of measured drift velocities with neutral wind velocities predicted by models is provided. The observed velocities usually exceeded the horizontal neutral wind velocities predicted by the HWM14 model for the locations and times of observations.
Fil: Chum, Jaroslav. Institute of Atmospheric Physics; República Checa
Fil: Liu, Jann Yenq. National Central University. Institute of Space Science; República de China
Fil: Chen, Shih Ping. National Central University. Institute of Space Science; República de China
Fil: Cabrera, Miguel Angel. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Electricidad, Electrónica y Computación. Laboratorio de Telecomunicaciones; Argentina
Fil: Laštovička, Jan. Institute of Atmospheric Physics; República Checa
Fil: Baše, Jiří. Institute of Atmospheric Physics; República Checa
Fil: Burešová, Dalia. Institute of Atmospheric Physics; República Checa
Fil: Fišer, Jiří. Institute of Atmospheric Physics; República Checa
Fil: Hruška, František. Institute of Atmospheric Physics; República Checa
Fil: Ezquer, Rodolfo Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Tecnológica Nacional; Argentina
Subject
DOPPLER SOUNDING
EQUATORIAL IONIZATION ANOMALY
EQUATORIAL SPREAD F
GPS SIGNAL OCCULTATION AND SCINTILLATION
IONOSPHERIC IRREGULARITIES
PLASMA BUBBLES
REMOTE SENSING
Meteorología y Ciencias Atmosféricas
Ciencias de la Tierra y relacionadas con el Medio Ambiente
CIENCIAS NATURALES Y EXACTAS
Access level
Open access
License
https://creativecommons.org/licenses/by/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/58088