We analyze the data recorded during December 2011–November 2012 by a digitalionosonde 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 comparativestudy of ionospheric scintillations and spread F. A good consistency betweenthe temporal variations of GPS scintillation (represented by the S4 index) andof ionogram spread F (represented by the QF index) is found in thepre-midnight periodduring equinox. However in the post-midnight period during equinox and inthe period from post-sunset to pre-sunrise during June solstice, moderatespread F is seen without concurrent GPS scintillation. The possible causeresponsible for the difference between post-midnight GPS scintillation andspread F during equinox could be due to the decaying of 400 m scaleirregularities associated with equatorial spread F. Regarding theirregularities producing moderate QF and low S4 indices during Junesolstice, we suggest that the frequently observed sporadic E (Es) layer andthe medium-scale traveling ionospheric disturbances (MSTIDs) over Sanyacould play important roles in triggering the June solstitialspread-F events.
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