Study on coupling of the mesosphere and ionosphere in the equatorial region by means of airglow imaging and ionospheric sounding

Abstract

Coupling between the ionospheric plasma bubbles and atmospheric gravity waves has been an important issue for investigation of the ionospheric irregularities and plasma bubble seeding and development. The plasma bubbles occur in the equatorial ionosphere and affect not only radio telecommunications but also ground positioning system by GNSS satellites. Today, this is an important theme in the area of Space weather, too. The present proposal has an object to study dynamical process in the mesosphere from 80 to 100 km of altitude and the process of the ionospheric plasma bubble formation in the 250-300 km of altitude. The gravity waves will be observed by an airglow all-sky imager and mesospheric winds by a meteor radar. The bubble generation and development will be monitored by the imager (for the OI 6300 emission), ionosonde and VHF radar. Scientific objectives are; (1) to study the mesospheric gravity waves those propagating into the ionosphere using Ray-tracing techniques, (2) to study seeding and development processes of the bubbles, (3) to investigate contribution of the gravity waves in formation of the ionospheric bubbles. The student (candidate of the present proposal) will take the graduate courses in the first academic year, ionospheric physics, atmospheric modeling and instrumentations (imager, ionosonde and VHF radar). In the second year, he should take a special course for Ray-tracing technique applying into an atmospheric model, in addition to image data analysis. In the third year, a simulation model for the gravity wave propagation and perturbation of the ionosphere and Rayleigh-Taylor instability and formation of the bubbles will be developed. The present work is a theory and half-experimental work and to achieve to further understanding in the plasma bubble seeding mechanism. The subject has a new aspect in the area of the equatorial ionosphere study.