S320p.19 — Analysis of the Solar Diameter Variations at July, 1986 and the Geomagnetic Storm of March, 1989

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Alexandre Humberto Andrei2, Marcos A. Garcia2, Andres R.R. Papa2, Sergio Calderari Boscardin2, Jucira Lousada Penna2, Costantino Sigismondi1

Institution(s): 1. ICRA, 2. Observatorio Nacional/MCTI

In this work, we have a well-known event in scientific literature used to illustrate our investigation on the viability of the solar diameter variation be a precursor for the occurrence of sets of coronal mass ejections, and thus, for geomagnetic storms, as noted in previous works of our group, but now, in a time scale of a few days. The selected event was that of March 13, 1989, a strong geomagnetic storm that made the Hydro-Quebec power grid fall down by 9 hours, damaging the local economy in millions of dollars. At the same time we have investigated a time interval belonging to a solar minimum period, on July 1986, prior to the rising phase and solar maximum of Solar Cycle 22, to compare with the geomagnetic pattern, as well as with the solar diameter behavior along these periods of low solar and geomagnetic activity. We used the time series of the CERGA’s astrolabe (because its dataset is long enough as to comprise both time periods of the analysis), the geomagnetic index AP and the H geomagnetic component from the Tatuoca Magnetic Observatory (because it is near to the geomagnetic equator and with the extra aim of checking the sensitivity of its magnetometers to global events).