Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B

Balloon-borne studies of magnetospheric electrodynamics
Edgar A. Bering
Professor of Physics and ECE, University of Houston




The MINIS balloon campaign in January 2005 investigated relativistic electron loss mechanisms. Balloon-based experiments directly measure precipitation and thus provide a method for quantifying losses, while the nearly stationary platform allows for the separation of temporal and spatial variations. Four balloons, each carrying an X-ray spectrometer, a Z-axis search coil magnetometer, and a 3-axis electric field instrument providing DC electric field and VLF measurements in 3 frequency bands, were launched from the South African Antarctic Station (SANAE). The launches took place at 1400 UT on 17 January, 1309 UT on 19 January, 2115 UT on 20 January, and 0950 UT on 24 January 24 2005. Each payload was be carried to 110,000 ft ($\sim$32 km) on a 300,000 cubic foot balloon; 3 of the 4 remained at float altitude for about 8 days, ranging from L$\sim$4 into the polar cap. An X 7.1 solar flare occurred at 0636 UT on 20 January 2005 and reached peak intensity at 0701UT. The largest >100 MeV solar proton event of the spacecraft era began at 0650 UT and reached peak intensity at 0710 UT. This flare appears to have essentially shorted out the global circuit and virtually stopped magnetospheric convection for at least 7 hours. The paper will present details of these findings and review the recovery. A CME from this flare arrived at the Earth 34 hours later. An SSC began at ~1650 UT followed by a geomagnetic storm with a Dst perturbation of ~-100nT. The arrival of the CME initiated an interval of very strong relativistic electron precipitation. The second and third Southern payloads made observations extensive relativistic electron precipitation events that occurred from 1700 to 2000 UT on 21 January 2005. This paper will present a study of the correlations in X-ray modulation between payloads.


Friday, 6 April 2012

Globe Room, Elvey Building

3:45 PM