We present observational evidence that eruptions of quiescent filaments and associated coronal mass ejections (CMEs) occur as a consequence of the destabilization of large‐scale coronal arcades due to interactions between these structures and new and growing active regions. Both statistical and case studies have been carried out. In a case study of a “bugle” observed by the High‐Altitude Observatory Solar Maximum Mission coronagraph, the high‐resolution magnetograms from the Big Bear Solar Observatory show newly emerging and rapidly changing flux in the magnetic fields that apparently underlie the bugle. For other case studies and in the statistical work the eruption of major quiescent filaments was taken as a proxy for CME eruption. We have found that two thirds of the quiescent‐filament‐associated CMEs occurred after substantial amounts of new magnetic flux emerged in the vicinity of the filament. In addition, in a study of all major quiescent filaments and active regions appearing in a 2‐month period we found that 17 of the 22 filaments that were associated with new active regions erupted and 26 of the 31 filaments that were not associated with new flux did not erupt. In all cases in which the new flux was oriented favorably for reconnection with the preexisting large‐scale coronal arcades; the filament was observed to erupt. The appearance of the new flux in the form of new active regions begins a few days before the eruption and typically is still occurring at the time of the eruption. A CME initiation scenario taking account of these observational results is proposed.

The geosynchronous ATS 6 environmental measurements experiment was operated during 15 evening passes when the SCATHA spacecraft was within 1-2 RE and both spacecraft were very near the geomagnetic equator. Numerous, well-defined substorm injections were recorded at both spacecraft with varying local time and radial separations. Accurate delay timing was possible since these events exhibit abrupt and essentially dispersionless (to within 10 s) plasma flux changes which replace cool preexisting plasma with hot quasi-Maxwellian distributions. The hot plasma propagates earthward in close association with an equally abrupt magnetic field increase at velocities in the range of 10-100 km/s. On this basis we identify the agent of injection as the induced electric field of the earthward propagating compression wave observed by Russell and McPherron (1973), and we refer to the propagating particle structure as the injection front. These dramatic synchronous orbit electron injection signatures are produced mainly by a boundary motion rather than by local acceleration of plasma. However, we find some evidence that the plasma sheet electrons are weakly 'heated' by the passage of each compression wave, the energy appearing mainly in the high-energy tail of the distribution. The spectral change we observe argues convincingly that the boundary in question is a precipitation-flow boundary layer (Kennel, 1969) and that the near-earth plasma sheet is significantly degraded in average energy by the addition of ionospheric plasma, especially secondary electrons emitted by the ionosphere due to precipitating energetic electrons. The presence of significant •B/•t requires that a change of mapping occur between the equatorial plane and the ionosphere, the sense being such as to map the inward moving injection front to a relatively fixed latitude in the ionosphere. Such an earthward plasma injection would not therefore require equatorward auroral motion. tionary orbit can be reproduced equally well by an injection boundary model, or a model with varying convection electric field, or a hybrid model with spatially limited time-varying electric and magnetic fields [Kivelson et al., 1980, and refer-Copyright ¸ 1981 by the American Geophysical Union. Paper number IA0733. 0148-0227/81/00 IA-0733501.00 • ences therein]. This situation illustrates the nonuniqueness of conclusions drawn from a single-satellite data set and the need for multiple-satellite observations to constrain the modeling process. This paper is an attempt to learn from the comparison of plasma data sets from ATS 6 and SCATHA relating to several substorm events. An example of the success of the first point of view appears in the paper by Barfield et al. [1977], in which an impulsive injection of plasma is observed at ATS 5 and then 11 rain later at Explorer 45, 1.2 RE earthward and at approximately the same local time. Assuming that an energetic plasma was created and released beyond a sharp, azimuthally extended boundary outside synchronous orbit, the authors were able to bui...

Recent research has established the reality of the 80 to 100-year cycle (long cycle) in solar-terrestrial phenomena that for many years has been suspected to occur. This paper investigates some of the systematic changes that took place during the most recent long cycle. The variations of one hundred years of data on the aa imJex of geomagnetic activity are reinvestigated. Since the solar wind drives geomagnetic activity the results of the study are interpreted in terms of the solar wind. It is shown that the l 1-year solar cycle as expressed by the number of sunspots (the sunspot cycle) is very different from the 11-year solar cycle as expressed by the solar wind and geomagnetics (the solar wind cycle). With an objective technique, using only sunspot numbers and not involving any judgement as to the transient or recurrent nature of any geomagnetic activity, the solar wind cycle is decomposed into the sun of two equally strong periodic variations, each having the period of the sunspot cycle, but differing in phase. One term in the decomposition, the R component, is chosen to have the phase and relative amplitude of the sunspot cycle. The other term in the decomposition, the I component, is found to be almost, but not quite, 180 ø out of the phase with R and to have very closely related amplitudes. The source of the R component is shown to be sporadic or short-lived solar events and that of the I component is shown to be long lived solar features such as coronal holes. The amplitudes are interpreted as being due to solar wind parameters, probably lB zlV 2. The solar wind observed at earth oscillates rhythmically between the two sources. The amplitude of both the oscillations increased smoothly and steadily from 1900 to 1960, corresponding to the ascending branch of the long cycle of solar activity which has been established elsewhere as occuring in the solar wind with an average period since the Middle Ages of 87 years. From these results it is concluded that there is a very strong relationship between coronal conditions at the sites of origin of long lived streams of solar wind and the corresponding sites of sporadic and/or short lived events 5 or 6 years later. Moreover, there is a remarkable and orderly evolution of these conditions over at least 60 years. The interruption of the smooth evolution in 1960 suggests we are now in the declining phase of the long cycle, which is to be expected since the average cycle period is 87 years and the last minimum was in the first decade of this century.

We describe an updated predictive engineering model for the interplanetary fluence of protons with energies >1, >4, >10, >30, and >60 MeV. This has been the first opportunity to derive a model from a data set that has been collected in space over a long enough period of time to produce a valid sample of solar proton events. The model provides a quantitative basis for estimating the exposures to solar protons of spacecraft during missions of varying length and of surfaces and atmospheres of solar system objects. It is derived from the set of data collected by the IMP and OGO spacecraft between 1963 and 1991. The >10 and >30 MeV data sets cover the period from 1963 to day 126 of 1991. The >1, >4, and >60 MeV data sets were collected between 1973 and 1991. Both data sets contain several major proton events (>10-MeV fluences exceeding 3 or 4 x 109 protons/cm 2) comparable to the 1972 event. The method of statistical analysis used in producing the model of the proton environment is the same as that used for earlier models. For the cases of the >10 and >30 MeV particles, the fluences are somewhat lower than in our earlier model (JPL 85). No >1, >4, and >60 MeV proton fluence models have been published in the literature previously. We present our results in a convenient graphical form which may be used to calculate the 1 AU fluence expected at a given confidence level as a function of the length of the exposure. A method of extending this estimate to other heliocentric distances is described. 13,281 13,282 FEYNMAN ET AL.: INTERPLANEI'ARY PROTON FLUENCE MODEL REFERENCES Armstrong, T. P., C. Brungardt, and J. E. Meyer, Satellite observations of interplanetary and polar cap solar particle fluxes from 1963 to the present, in Weather and Climate Responses to Solar Variations, edited by B. M. McCormac, pp. 71-79, Colorado University Press, Boulder, 1983. Feynman, J., T. P. Armstrong, L. Dao-Gibner, and S. M. Silverman, A new interplanetary proton fluenee model, J. Spacecr. Rockets, 27, 403, 1990a. 13,294 FEYNM• ET AL.: INTERPLANEFARY PROTON FLUF•CE MODEL Feynman, J., T. P. Armstrong, L.

Beginning with a list of severe geomagnetic storms, we obtain an estimate of the maximum solar wind flow speed at Earth during the past -50 years. We do this by (1) focusing on the subset of severe storms that followed major proton flares (since large proton events are strongly associated with fast coronal mass ejections), (2) calculating the average speed of the associated interplanetary shocks from the time intervals between the flares and the onsets of the storms, and (3) using an empirical relationship between the average shock speed and the maximum flow speed of the associated transient stream to infer a peak flow velocity for each event. We find no evidence for bulk flow velocities greater than the •>2000-km/s value deduced from Prognoz 2 and HEOS 2 in situ plasma measurements for the August 4, 1972, event. The •>2000-km/s speed for that event does not appear to be anomalously high, however; there are other credible events, occurring before 1960, with inferred flow speeds approaching this value. The •>2000-km/s value lies at the high-speed edge of a reasonable single distribution of peak solar wind speeds for a representative sample of the most energetic solar-terrestrial events observed from 1938 to 1989. 1.This study was undertaken to estimate the highest flow velocity that the solar wind has exhibited at Earth during the past -50 years. Such an estimate should serve as a benchmark for the severity of solar wind disturbances. In addition, determination of the maximum wind speed is important for the design of plasma instruments to be flown in space, especially those to be used to monitor or study the transient high-speed streams responsible for major geomagnetic activity.Systematic in situ observations of the solar wind began in late 1962 [Neugebauer and Snyder, 1966] and have continued, with few interruptions and varying degrees of completeness, to the present time [see King, 1977, 1979; Couzens and King, 1986]. Despite this long run of observations, no firm determination has yet been made of the maximum solar wind flow velocity because many plasma instruments have been driven off scale for the highest-speed events. The fastest solar wind that has been reported to date from in situ observations in the vicinity of the Earth was associated with the flare of August 4, 1972, for which velocities of •>2000 km/s were deduced from Prognoz 2 measurements [Zastenker et al., 1978; see Cambou et al., 1975; Vaisberg and Zastenker, 1976; d'Uston et al., 1977]; for the same event, HEOS 2 observed speeds of-1800 km/s [Grunwaldt, 1975; Vaisberg and Zastenker, 1976; see Rosenbauer et al., 1972; Cambou et al., 1975]. Both of these values require qualification. The inferred maximum wind speed at Prognoz 2 on August 4-5, 1972, was beyond the 1700-km/s operating range [Cambou et al., 1972; d'Uston et al., 1977] of the Calipso plasma experiment, while HEOS 2 was probably in the magnetosheath at the time of the peak -1800-km/s measurement [Cattaneo et al.d' Uston et al., 1977]. There are reports of high-velocity wind during oth...