Brazilian low latitude MSTIDs possibly associated with - DGE

Brazilian low latitude MSTIDs possibly associated with tropospheric
activity sources at mid-latitudes
Claudia Maria Nicoli Candido - Instituto Nacional de Pesquisas Espaciais - INPE
([email protected])
Alexandre Alvares Pimenta - Instituto Nacional de Pesquisas Espaciais - INPE
Fabio Becker-Guedes - Instituto Nacional de Pesquisas Espaciais - INPE
Cristiano Max Wrasse - Universidade do Vale do Paraíba - UNIVAP
E-mail for contact: [email protected]
Abstract
In this work we present some cases of occurrence of medium scale traveling ionospheric
disturbances, MSTIDs, observed over a Brazilian low latitude site, Cachoeira Paulista (23.2 S,
45.0 W) and their possible sources. TIDs are perturbations on the plasma density associated
with gravity waves propagating through the ionosphere. Their origin can be associated to two
mainly sources: geomagnetic activity over auroral regions or large meteorological activity in the
troposphere which seeds movements of the neutral atmosphere, generating gravity waves
which reach ionospheric F-region heights. The occurrence of low latitude MSTIDs using
simultaneous OI 630.0 nm emission imaging and ionospheric sounding (ionosondes) during
quiet geomagnetic conditions were recently reported. It was revealed dark bands structures
propagating to northwest direction associated with the F-region uplifting indicated by the
minimum virtual height (hâ?²F) and F-region peak density (foF2) depletions. The meteorological
satellite (METEOSAT) observations and the winds and omega (Pa/s) from NCEP site show
intense tropospheric disturbances in the mid-latitudes. We investigate these tropospheric
disturbances in the mid-latitude region as possible source for Brazilian MSTIDs.