Heliospheric shocks (excluding planetary bow shocks)

Even though it took place less than halfway through the last four year period, the AGU Chapman Conference in Napa Valley, California, during February, 1984, highlighted in many ways current U. S. contributions to the study of heliospheric shocks. Considerable recent progress in the theoretical understanding of these discontinuities has been summarized in the collections of the review papers from the Conference, so that those excellent papers have been an important source for the preparation of this Report. In addition, detailed analyses of ISEE‐3 interplanetary shock observations, and reports on additional data from the outer heliosphere, particularly major disturbances during 1982, have been published since the last Quadrennial Report, and are summarized hereafter. The Pioneer and Voyager spacecraft in the outer heliosphere also have traveled closer to the heliospheric boundary, and further inferences of the boundary location have been made, although it has not yet been directly detected. In addition, details are not yet available concerning the type of shock transition with which it may be associated. More general characteristics of shocks in the outer heliosphere, and out of the solar equatorial plane to ∼25 deg latitude or more, are available from the Pioneer and Voyager data. Also, collection and analyses of data from the inner heliosphere have been extended. Finally, new analyses and observations of coronal shocks have been done, and theoretical studies of this phenomenon have been advanced.