The extreme solar flares of October 28th and November 4th, 2003 and resultant 
extreme ionospheric effects

B. T. Tsurutani (1,2), D. L. Judge (2), A. R. Jones (2), F. L. Guarnieri (1,2,3),
G.A. Zambon (2), P. Gangopadhyay (2), M. Harmon (2), J. Nuttall (2) , 
D.E. Shemansky (2) , A. Mannucci (1), B. Iijima (1), G. Hajj (1) , T. N. Woods (4), 
L. Floyd (5), R. R. Meier (6), J. Huba (7), S. C. Solomon (8), S. Mende (9), 
T.J. Immel (9), J. U. Kozyra (10), J. Pap (11)

(1) Jet Propulsion Laboratory
(2) University of Southern California
(3) Instituto Nacional de Pesquisas Espaciais INPE
(4) LASP, University of Colorado
(5) Interferometrics, Inc.
(6) E.O. Hulburt Center, Naval Research Laboratory
(7) Plasma Physics Division Naval Research Laboratory
(8) High Altitude Observatory, UCAR
(9) Space Sciences Laboratory, Univ. CalIfornia at Berkeley
(10) The University of Michigan
(11) Goddard Space Flight Center


Some of the most intense solar flares in recorded history occurred at the end of
2003. The November 4th event is the largest on record (X28) and the October 28th
flare was the fourth most intense (X17). These will be compared/contrasted to the
July 14, 2000 Bastille Day (X6) event. We use SOHO EUV (SEM), GOES and TIMED x-ray
data to characterize the flare spectral energy versus time. High time resolution,
approximately 1s ground base GPS data are used to examine the abrupt increase in
path-integrated ionospheric total electron content (TEC). It will be shown that
the dayside ionosphere responds dramatically to the x-ray, FUV and EUV input by an
abrupt approximately 20-25% increase in ionospheric TEC. Polar and IMAGE UV
spectra are used to quantify the dayglow enhancements. The TEC increases are
nonlinearly related to the peak flare intensities. The reasons for this are not
understood at this time. Ionospheric models using the flare input data will be
used to compared against tomographic analyses of the GPS information.

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Presented at the 35th COSPAR Scientific Assembly, Paris, France, July 18-25, 2004.