A case study on ionospheric scintillations at low latitude associated with a plasma blob observed in situ

Abstract

In general, ionospheric scintillations at low latitude are considered as signatures of equatorial plasma bubbles (depletions). However, some authors considered that scintillations may also be associated with plasma blobs (enhancements), but there was no in situ measurement hitherto to confirm it. We performed a case study on the concurrent observation of an ionospheric plasma blob with in situ measurements by ROCSAT-1 (i.e. Formosa satellite-1) and of GPS amplitude scintillations in the low-latitude ionosphere on 1 June 2003. The blob measured in situ had a scale size of about 800 km in the F layer, and the ion density inside the blob was severely disturbed. Amplitude scintillation with S4 > 0.3 was observed concurrently in the same longitude range as the blob measured. This case study provides evidence of simultaneously observed GPS amplitude scintillations and a blob in situ, and it confirms that scintillations can be associated with plasma blobs in the low-latitude ionosphere.