Metric Type III radio bursts are nearly always associated with solar active regions. In particular, the occurrence of Type III bursts within a few minutes of the onset of the solar flares (Wild et al. 1954) is well known. During the Skylab period, a broad peak in the number of isolated Type III bursts occurred about 5 h prior to large Hα solar flares (Jackson and Sheridan 1979).

Stewart et al. (1978) have reported moving Type IV solar metre-wave radio outbursts with brightness temperatures between 108 and 1010 K. We now report Culgoora radioheliograph observations of four more Type IV radio sources, some moving, some stationary, but all with brightness temperatures above 109 K, and one with a brightness temperature above 1013 K. We also describe one of the previously reported events (that of 1977 September 20) in more detail. The interest of these events is that their high brightnesses place great strain upon the gyro-synchrotron theory of radio emission.

This paper describes the main features of the 8 May 1979 solar mass ejection, including the eruption of a polar crown filament to 1.5 R ⊙ during 0810-1036 UT and the passage of material through the outer corona, from 2.6 to 10.0 R⊙, during 1028-1246 UT.

Observations of cosmic ray intensity depressions by earth bound neutron monitors and measurements of interplanetary parameter's variations aboard geocentric satellites in the period January 1972-July 1974 are analysed and grouped according to their correlation among them. From this analysis of about 30 cases it came out that the majority of the depressions correlates with the average propagation speed of interplanetary shocks as well as with the amplitude of the interplanetary magnetic field after the eruption of a solar flare. About one fourth of the events correlates with corotating fast solar wind streams. As the recovery time of the shock-related depressions depends strongly on the heliographic longitude of the causitive solar flare, it seems that the cosmic ray modulation region has a corotative-like feature.

The analysis of solar wind (bulk velocity v, proton density n, proton temperature T) and magnetic field (B) data in the years 1964-1974 makes possible to identify two main classes of high-speed streams (ΔV = (vm - vo)≥ 100 km/sec, vm being the maximum daily mean speed and vo the mean value between the speeds immediately preceding and following the stream; duration Δt ≥ 2 days):

Most observations of interplanetary scintillations of radio sources are made at frequencies around 80 MHz. These observations are limited to regions close to the sun, where the scintillations are maximum at this frequency. It is possible to extend these observations to the weakly scattering regions beyond 1 A.U. by making measurements at low frequencies. We have built a low frequency antenna system at Gauribidanur, India (Lat. 13° 36′ N and Long. 5 hrs. 10 min.), which can be used for this purpose. Although this system will not be dedicated to IPS, we intend to use it exclusively for solar wind observations during periods of interest.

A 3-station interplanetary scintillation (IPS) observatory is being developed mainly with a view to study the solar wind plasma. The first IPS telescope operating at 103 MHz at Thaltej near Ahmedabad has been put into regular operation since April 1979. With only half the antenna aperture (≃2500 m2) presently in use, observations of 8-10 sources are being made to calculate scintillation index, temporal spectrum of intensity fluctuations and scale size of density irregularities.

Dynamical behaviour of a flare-generated disturbance can be followed by IPS observations through a comparison between the IPS observations and a model of the disturbance. The highly turbulent post-shock plasma can be attributed to the contact surface of the disturbance. Two examples of IPS observations of flare-generated disturbances will be discussed.

On August 27, 1978, a major geomagnetic storm began which eventually resulted in short period geomagnetic fluctuations of over 500 gammas in Boulder, and sightings of aurora as far south as Santa Fe, New Mexico. This storm was not obviously precipitated by flare or coronal hole solar plasma, but was apparently associated with a large solar filament which abruptly disappeared on August 23, 1978. Prelimininary results of a study inspired by this storm are that 16 of the 59 geomagnetic storms which have occurred since the beginning of the current 11 year solar cycle can only be traced to disappearing filaments and some of the other storms which have been blamed on flares or coronal holes are also associated with disappearing filaments. Filament eruptions have been identified with coronal mass ejections, especially those observed with the Skylab white-light coronograph. However, there are some points of difference between typical coronal transients and geoactive coronal transients which may suggest fruitful research.

A new classification of large solar flares is presented. If the time spacings between the flares are over 2.5 days, the flares and the corresponding interplanetary streams are classified as isolated ones. The concepts of the nearest, intermediate and distant flare zones (N, I and D zones) are introduced. The limits of the zones are determined at 30° longitude intervals and at 15° latitude ones. The classification is applied to the flares of 1966-1974 (Ivanov et al., 1979). It allows one to study the interplanetary and the magnetospherical disturbances more systematically.

The reasons for nonstationary hydrodynamic flows in solar atmospere are reviewed. It is emphasized that a rapid local heating of corona or upper chromosphere can scarcely provide a very large mass of solar plasma ejections observed in corona and interplanetary space. We suggest that coronal transients and interplanetary ejections are produced by magnetic field evolving in solar atmosphere. Magnetic reconnection in current sheets can play essential role in this process. The suitable approximation of strong magnetic field is formulated. Some solutions of MHD equations in this approximation are demonstrated. Their applications to coronal conditions are discussed.

Recent theoretical studies on Traveling Interplanetary Phenomena (TIP) and their relation or presumed relation to their solar origins will be reviewed. An attempt is made to outline the theoretical studies in the context of mathematical methods and physical processes. The following alternative approaches are examined: analytical vs. numerical methods; magnetohydrodynamics vs. hydrodynamics; processes with or without dissipation; continuum (macroscopic) vs. the kinetic (microscopic) approach. In particular, the flare-generated interplanetary shocks are used as examples to illustrate these theoretical studies within the context of TIP. Some emphasis will be placed on MHD wave propagation through the inner corona and its maturity to a fully-developed interplanetary shock. Further, their propagation and the disturbing effects on the solar wind will be considered. Cases concerning the classification and characteristics of blast-produced shocks and long-lasting ejecta are also discussed in the context of numerical simulations.

Three ways to improve the theory and therefore the understanding of the physical processes in the interplanetary medium (during both quiet and disturbed periods of solar activity) are suggested. They are: (1) the development and consequently the use of higher order moments (fluid) equations as well as of more realistic closure conditions and transport coefficients for the macroscopic description of the solar wind ; (2) the undertaking of computer simulation experiments on the nonlinear collective relaxation process through particle-wave-particle interaction due to the plasma electromagnetic instabilities which may develop under conditions prevailing in the solar wind; and (3) the consideration of collective interactions in the evaluation of the transport coefficients, as deduced from the quasi-linear theory and computer simulation experiments, and their incorporation into the higher order moment equations.

The role of the magnetic field in a coronal mass ejection event has not been unequivocally defined, and may in fact be quite variable in view of the large variety of shapes and sizes of coronal transients. Measurements of the magnetic field associated with these events have thus far been inferred from simultaneously observed radio bursts, which provide no information on the direction of the field and are limited in spatial resolution. Substantial improvement in these two areas could be achieved by continuous monitoring of the Faraday rotation of a linearly polarized spacecraft signal during solar occultation. A coronal event traversing the line-of-sight would yield a characteristic profile in cross section, which would be of value for discriminating between the various models of coronal transients.

Several classes or types of coronal transients are believed to originate near the solar surface at the base of pre-existing coronal magnetic loops. These loops often lie beneath an overlying open-field region in a typical coronal- or helmet-streamer configuration. Recent experimental results indicate that these pre-existing magnetic loops may be torn open by the explosive force of the solar phenomena responsible for the transient. Numerical solutions of the time-dependent, two-dimensional, dissipationless, MHD equations of motion (the equations are discussed by Steinolfson et al. (1978)) are used to examine the formation of a coronal streamer magnetic structure and the evolution of the streamer following an explosive solar event in the closed-field region.

Solution of the nonlinear MHD problem of plasma flow in an increasing dipolar magnetic field is obtained in the approximation of a strong field. The distributions of plasma velocity, displacement, and density are calculated. The situation when the magnetic dipole is ‘increased’ by rapid process of magnetic reconnection or current sheet rupture is illustrated. Possible applications are discussed in connection with plasma ejections from chromosphere in corona.

Numerical solutions for problem of hydrodynamic response of the inhomogeneous (exponential) atmosphere on impulsive heating by energetic electrons or by very high-temperature thermal fluxes are discussed.

Numerical results are obtained for non-plane MHD responses to a sudden energy release in a stratified model atmosphere. In agreement with observations, it is shown that after the energy release, the magnetic field affected by the energy release relaxes toward the potential configuration while the outer atmospheric fields increase its shear. Additional results suggest a new way of interpreting the energy storage and release in repeated flares.

It has been confirmed that the high-speed solar wind flows out of the coronal holes at low latitudes, where the magnetic fields open and the temperature is low (e.g., Krieger et al. 1973). But there has not been direct observation of the solar wind out of the polar regions of corona. We report here that the observations of interplanetary scintillation (IPS) show the existence of the high-speed flow of 800 km/s out of the polar coronal regions and the well-coincidence to the model of the coronal holes extending from the polar regions.

In the past few years, numerical studies of corona-interplanetary dynamics have been undertaken by many investigators. The results, as summarized by Wu et al. (1977), indicate that this approach seems very promising and worthy of further pursuit. So far, the calculations have been performed on two-dimensional codes, to simulate magneto-hydrodynamic flow in a meridional plane or in the equatorial plane. In order to fully account for the global features of the corona-interplanetary phenomenon, it is necessary to do three-dimensional calculations. Here we discuss some groundwork for the formulation of a time-dependent three-dimensional code.