Variation of ionospheric slab thickness observations at Chumphon equatorial magnetic location

Abstract

This study presents the diurnal and seasonal variations of slab thickness at the equatorial magnetic latitudes in Thailand during [2004][2005][2006], corresponding to the declining part of low solar activity. The GPS-derived total electron content (TEC) and the maximum electron density of the F-region (N m F 2 ) are used to compute the slab thickness (τ ) at the Chumphon station (10.72• N, 99.37• E), located near the magnetic equator. The results show that large peaks of slab thickness exist during the pre-sunrise hours in all three seasons at Chumphon when compared with other latitudes. The maximum value of slab thickness occurs when the peak electron density in the F 2 region is at the lowest level. During daytime, the slab thickness ranges from 200 kilometers to 580 kilometers for all seasons. During nighttime, the maximum value of slab thickness is 1250 kilometers in the summer of 2004. Moreover, the diurnal variation shows two minima that appear around 0900 LT and 1900 LT, during the post-sunrise and sunset hours. The seasonal variations show that the average slab thickness daily value is greater during summer and winter than those during equinox. Our study finds that the slab thickness at Chumphon located near the equatorial latitude is much larger than those found at low, mid, and high latitudes. The difference in slab thickness between the equatorial latitude and other zones is explained by the lack of plasma flow from the plasmasphere to the F 2 region at the magnetic equator.

Ionospheric slab thickness at the equatorial anomaly region after the deep solar minimum of cycle 23/24

“…Many other studies have reported for different longitudinal sectors that the ionospheric slab thickness also depends on diurnal, seasonal, solar activity, latitudinal and geomagnetic activity variations (e.g. Bhonsle et al, 1965;Titheridge, 1973;Kersley and Hajeb-Hosseinieh, 1976;Bhuyan et al, 1986;Davies and Liu, 1991;Jayachandran et al, 2004;Gulyaeva and Stanislawska, 2005;Kenpankho et al, 2011;Venkatesh et al, 2011). Jayachandran et al (2004) reported an ionosphere more thick during high solar activity when compared to low solar activity period.…”

A global picture of ionospheric slab thickness derived from GIM TEC and COSMIC radio occultation observations

“…EST provides an alternative way to interpret H. Once we have EST, we could estimate H and further the electron density profile. Thus, the spatial, temporal, and solar activity features of EST have been studied worldwide [Breed et al, 1997;Chuo et al, 2010;Dabas et al, 1993;Davies and Liu, 1991;Duarte-Silva et al, 2015;Goodwin et al, 1995aGoodwin et al, , 1995bGulyaeva, 2007;Gulyaeva et al, 2004;Jin et al, 2007;Kenpankho et al, 2011;Kouris et al, 2008;Stankov and Warnant, 2009]. Moreover, geomagnetic storms are also found to influence EST [e.g., Àlàgbé, 2012;Chuo et al, 2010;Gulyaeva, 2007].…”

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

“…Bhonsle et al, 1965;Titheridge, 1973;Huang, 1983). Based on most of the available and reliable observations of ionospheric TEC and NmF2, numerous analyses for recording the climatology of the slab thickness have been conducted over the past few decades (Jayachandran et al, 2004;Chuo, 2007;Jin et al, 2007;Stankov and Warnant, 2009;Guo et al, 2011;Kenpankho et al, 2011;Weng et al, 2012). Jayachandran et al (2004) investigated the variation in the slab thickness during the solar maximum and minimum phases of an intense solar cycle by using the hourly values of TEC and NmF2 at Hawaii (low latitude), Boulder (mid-latitude) and Goosebay (high latitude).…”