English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. The relation between the occurrence of ionospheric irregularities and the spatial gradient of total electron content (TEC) derived from two closely locatedstations (ASAB: 4.34 ∘  N, 114.39 ∘  E and DEBK: 3.71 ∘  N, 109.34 ∘  E, geomagnetic), located within the equatorial region,over Ethiopia, during the postsunset hours was investigated. In this study, the Global Positioning System (GPS)-derived TEC during the year 2014obtained from the two stations were employed to investigate the relationship between the gradient of TEC and occurrence of ionospheric irregularities. Thespatial gradient of TEC ( ΔTEC∕Δlong ) and its standard deviation over 15 min,  σ(ΔTEC∕Δlong ), were used in this study. Therate of change of TEC-derived indices (ROTI, ROTI ave ) were also utilized. Our results revealed that most of the maximum enhancement and reduction values in ΔTEC∕Δlong  are noticeable during the time period between 19:00 and 24:00 LT. In some cases, the peak values in the spatial gradientof TEC are also observed during daytime and postmidnight hours. The intensity level of  σ(ΔTEC∕Δlong)  observed after postsunset showsimilar trends with ROTI ave , and was stronger (weaker) during equinoctial (solstice) months. The observed enhancement of  σ(ΔTEC∕Δlong) in the equinoctial season shows an equinoctial asymmetry where the March equinox was greater than the September equinox. During the postsunset period, therelation between the spatial gradient of TEC obtained from two closely located Global Navigation Satellite System (GNSS) receivers and the equatorial electricfield (EEF) was observed. The variation in the gradient of TEC and ROTI ave  observed during the evening time period show similar trends with EEF with adelay of about 1–2 h between them. The relationship between  σ(ΔTEC∕Δlong)  and ROTI ave  correlate linearly with correlationcoefficient of  C=0.7975  and  C=0.7915  over ASAB and DEBK, respectively. The majority of the maximum enhancement and reduction in the spatial gradient of TECobserved during the evening time period may be associated with ionospheric irregularities or equatorial plasma bubbles. In addition to latitudinal gradients,the longitudinal gradient of TEC has contributed significantly to the TEC fluctuations.

annales geophysicae

Investigation of the relationship between the spatial gradient of total electron content (TEC) between two nearby stations and the occurrence of ionospheric irregularities