Bidirectional, field-aligned flows of low-energy particles in interplanetary space have been proposed as a possible signature of large-scale, looplike magnetic structures. We present the results of a survey of bidirectional anisotropy observations using data from the low-energy proton and magnetometer experiments on board ISEE 3 covering a 45-month period corresponding to the last solar maximum. During this period, 66 bidirectional flow (BDF) events have been identified, of which 48 could positively be associated with isolated magnetic field structures. We suggest that these structures are an interplanetary manifestation of coronal mass ejection (CME) events, and are able to group the BDF events into five classes according to the field signature of the related magnetic structure and the association or otherwise with an interplanetary shock. We conclude that the BDF events are an interplanetary signature not only of energetic, flare-associated transients but also low energy, nonflare CMEs. From a comparison of anisotropy signatures at 35 and 620 keV we conclude that our observations are most consistent with the transient magnetic structures being detached bubbles comprising closed loops or tightly wound cylindrical helices rather than extended tonguelike loops attached to the Sun at the time of observation. , 1984, 1986Schwenn, 1986]. In particular, the interplanetary signatures of energetic, flare-initiated CMEs have been widely studied, resulting in a general acceptance of the idea that most, if not all, interplanetary shock waves are produced by CME events. Evidence exists, however, that such energetic CME events are only a small fraction, perhaps 10% or less, of the total CME population [Gosling et al., 1974;Newkirk et al., 1981]. This idea is supported by the results of a study by Klein and Burlaga [1982] of so-called magnetic clouds, thought to be the magnetically contained ejecta from CMEs, in which they showed that only ca. one third of the 45 clouds identified had a positive shock association. Sime and Hundhausen [1987], in a study of looplike CMEs identified in SMM coronograph data, have analysed an event which they propose as a candidate for a coronal shock. They emphasize, however, that the event in question is atypical for the data set, and that the majority of SMM looplike CMEs cannot be identified with a shock front. In spite of the large body of correlative data linking CMEs observed close to the Sun to a range of interplanetary phenomena, detailed information is still lacking regarding the development of CMEs between the point at which they leave the field of view of space-borne coronagraphs and their detection in-situ by spacecraft in interplanetary space. Of particular importance in this respect is the magnetic field configurafion. The looplike topology seen in many coronagraph images of CMEs has been the basis for suggesting that at-tached, closed magnetic "bottles" could expand out to 1 AU and beyond in the manner proposed originally by Gold [1959]. On the other hand, as originally pointed out...

[1] We analyse 9 large solar energetic particle (SEP) events detected by the Ulysses spacecraft at high heliolatitudes during the recent solar maximum polar passes. Properties of time intensity profiles from the Ulysses/COSPIN instrument are compared with those measured by SOHO/COSTEP and Wind/3DP near Earth. We find that onset times and times to maximum at high latitude are delayed compared to in-ecliptic values. We show that the parameter which best orders these characteristics of time profiles is the difference in latitude between the associated flare and the spacecraft. We find that the presence of a shock is not necessary for the establishing of near equal intensities at Ulysses and in the ecliptic during the decay phase. The model of SEP acceleration by coronal mass ejection driven shocks does not appear to account for our observations, which would more easily be explained by particle diffusion across the interplanetary magnetic field.

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We use data from the Ulysses, Advanced Composition Explorer, and Solar Terrestrial Relations Observatory spacecraft to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen in two energy ranges from 4.5–15.6 MeV/nuc in the inner heliosphere for the first time during an A<0 part of the solar cycle. Using measurements from early 2007 to mid‐2008, we find that the radial gradient is ∼48 ± 13%/AU, consistent with previous inferences for A<0 and larger than that determined in the inner heliosphere for A>0. The latitudinal gradient is consistent with zero and in the range −0.3 to 0.4%/degree, suggesting that during A<0 these particles are not able to propagate into the inner heliosphere by rapid drift along the heliospheric current sheet if the tilt of the sheet is as large as 30 degrees.

We report observations of solar energetic particles obtained by the HI-SCALE and COSPIN/LET instruments onboard Ulysses during the period of isolated but intense solar activity in 2006 December, in the declining phase of the solar activity cycle. We present measurements of particle intensities and also discuss observations of particle anisotropies and composition in selected energy ranges. Active Region 10930 produced a series of major solar flares with the strongest one (X9.0) recorded on December 5 after it rotated into view on the solar east limb. Located over the South Pole of the Sun, at >72 • S heliographic latitude and 2.8 AU radial distance, Ulysses provided unique measurements for assessing the nature of particle propagation to high latitudes under near-minimum solar activity conditions, in a relatively undisturbed heliosphere. The observations seem to exclude the possibility that magnetic field lines originating at low latitudes reached Ulysses, suggesting either that the energetic particles observed as large solar energetic particle (SEP) events over the South Pole of the Sun in 2006 December were released when propagating coronal waves reached high-latitude field lines connected to Ulysses, or underwent perpendicular diffusion. We also discuss comparisons with energetic particle data acquired by the STEREO and Advanced Composition Explorer in the ecliptic plane near 1 AU during this period.