Abstract
Abstract. We analyze the data recorded during December 2011–November 2012 by a digital ionosonde and a GPS (Global Positioning System) scintillation and (total electron content) TEC receiver collocated at Sanya (109.6° E, 18.3° N; dip lat. 12.8° N), a low-latitude station in the Chinese longitude sector, to carry out a comparative study of ionospheric scintillations and spread F. A good consistency between the temporal variations of GPS scintillation (represented by the S4 index) and of ionogram spread F (represented by the QF index) is found in the pre-midnight period during equinox. However in the post-midnight period during equinox and in the period from post-sunset to pre-sunrise during June solstice, moderate spread F is seen without concurrent GPS scintillation. The possible cause responsible for the difference between post-midnight GPS scintillation and spread F during equinox could be due to the decaying of 400 m scale irregularities associated with equatorial spread F. Regarding the irregularities producing moderate QF and low S4 indices during June solstice, we suggest that the frequently observed sporadic E (Es) layer and the medium-scale traveling ionospheric disturbances (MSTIDs) over Sanya could play important roles in triggering the June solstitial spread-F events.
Highlights
The ionospheric F region irregularities are known as electron density inhomogeneous structures, and are mainly generated at night through ionospheric plasma instabilities
A case study of spread F and scintillations has shown two kinds of irregularities that appeared during equinox and June solstice, respectively (Li et al, 2012)
Both types are statistically investigated through analyzing the data collected from the GPS scintillation and TEC receiver, and the digital ionosonde at Sanya
Summary
The ionospheric F region irregularities are known as electron density inhomogeneous structures, and are mainly generated at night through ionospheric plasma instabilities. Numerous means of observations such as satellite in situ and ground-based receivers, radar, rocket, optical imager and ionosondes have been applied to study the spatial and temporal distributions and characteristics of the irregularities during the last few decades at equatorial, low, middle and high latitudes (Abdu et al, 1981; Hysell and Burcham, 1998; Sahai et al, 2000; Su et al, 2008; Lynn et al, 2011). Equatorial F region irregularities usually appear as depletions in plasma density evidenced from satellite in situ measurements and are extensively observed at equatorial and low-latitude stations in December in American longitudes, in June solstice in central Pacific longitudes, and at equinox in other longitudes (e.g., Burke et al, 2004; Li et al, 2008; Su et al, 2008).
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