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SOHO/EIT observations of an Earth-directed coronal mass ejection on May 12, 1997
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +3 more
An earth-directed coronal mass ejection (CME) was observed on May 12, 1997 by the SOHO Extreme ultraviolet Imaging Telescope (EIT). The CME, originating north of the central solar meridian, was later observed by the Large Angle Spectrometric Coronagraph (LASCO) as a “halo” CME: a bright expanding ring centered about the occulting disk. Beginning a…
The Sun's total irradiance: Cycles, trends and related climate change uncertainties since 1976
Fröhlich, Claus; Lean, Judith
A composite record of the Sun's total irradiance compiled from measurements made by five independent space-based radiometers since 1978 exhibits a prominent 11-year cycle with similar levels during 1986 and 1996, the two most recent minimum epochs of solar activity. This finding contradicts recent assertions of a 0.04% irradiance increase from the…
Ulysses' return to the slow solar wind
Forsyth, R.; Balogh, A.; McComas, D. J. +9 more
After ten long years of wandering the uncharted seas, Ulysses returned to his home port of Ithaca. Similarly, after its unprecedented five year odyssey through the previously uncharted regions over the poles of the Sun, the Ulysses spacecraft has returned to the slow, variable solar wind which dominates observations near the ecliptic plane. Solar …
Geomagnetic storms caused by coronal mass ejections (CMEs): March 1996 through June 1997
St. Cyr, O. C.; Paswaters, S. E.; Simnett, G. M. +7 more
(1) All but two geomagnetic storms with Kp ≥ 6 during the operating period (March 1996 through June 1997) of the Large Angle Spectroscopic Coronagraph (LASCO) experiment on the Solar and Heliospheric Observatory (SOHO) spacecraft can be traced to Coronal Mass Ejections (CMEs). (2) These geomagnetic storms are not related to high speed solar wind s…
X-ray coronal changes during Halo CMEs
St. Cyr, O. C.; Webb, D. F.; Lemen, J. R. +2 more
Using the Yohkoh soft X-ray images, we examine the coronal structures associated with “halo” coronal mass ejections (CMEs). These may correspond to events near solar disk center. Starting with a list of eleven confirmed halo CMEs over the time range from December 1996 through May 1997, we find seven with surface features identifiable in soft X-ray…
LASCO observations of an Earth-directed coronal mass ejection on May 12, 1997
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +5 more
Coronal mass ejections (CMEs) that occur near the center of the solar disk are most likely to impact Earth. Detection of such events as ‘halos’ in white-light coronagraphs has been somewhat controversial in recent years. We present observations from the LASCO coronagraphs on SOHO that provide convincing evidence of the detection of an Earth-direct…
On the relationship between coronal mass ejections and magnetic clouds
Thompson, B. J.; Nitta, N.; Steinberg, J. T. +9 more
We compare the substructures of the 1997 February 07 coronal mass ejection (CME) observed near the Sun with a corresponding event in the interplanetary medium to determine the origin of magnetic clouds (MCs). We find that the eruptive prominence core of the CME observed near the Sun may not directly become a magnetic cloud as suggested by some aut…
Cradle to grave tracking of the January 6-11,1997 Sun-Earth connection event
Thompson, B. J.; Fox, N. J.; Peredo, M.
During the interval January 6-11, 1997, the satellites and ground facilities of the International Solar-Terrestrial Physics (ISTP) “Observatory” tracked a solar eruption from the Sun to the Earth. The resulting Coronal Mass Ejection (CME) took four days to travel through interplanetary space before arriving at Earth, where it caused electromagneti…
Differences in the O7+/O6+ ratio of magnetic cloud and non-cloud coronal mass ejections
Livi, S.; Woch, J.; Schwenn, R. +7 more
On its trajectory to Jupiter and over the poles of the Sun the Ulysses spacecraft has observed a considerable number of Coronal Mass Ejection (CME) transients in slow and in fast solar wind streams. The analysis of the magnetic field topology and the O7+/O6+ charge state ratio of 56 of these events has yielded strong evidence…
The solar origin of the January 1997 coronal mass ejection, magnetic cloud and geomagnetic storm
St. Cyr, O. C.; Webb, D. F.; Gopalswamy, N. +2 more
The magnetic cloud and geomagnetic storm on January 10-11, 1997 were associated with a halo-type Coronal Mass Ejection (CME) observed by the SOHO/LASCO coronagraphs near the sun on January 6. We summarize the solar activity related to this CME and the subsequent storm at Earth. This solar activity was remarkably weak and unimpressive. If the wide …