We present the results from a study of the dynamical properties of polar jets in the Sun's polar regions using LASCO C2 coronagraph and EIT observations. In the simplest impulsive acceleration scenarios for jets, gravity is expected to be the dominant force on the jet following the initial acceleration, especially in the Sun's polar regions where the open magnetic fields should not significantly impede the jet's motion. Our analysis shows that although at low heights the kinematics of the jets could be consistent with a gravitational deceleration of the ejected plasma, at higher heights their motions may simply follow the ambient solar wind outflow. If so, the polar jets can be used as tracers of the solar wind in coronal holes.

The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) is an absolutely calibrated UV spectrometer which has measured the solar spectral irradiance over the wavelengths 115-410 nm since October 1991. This data set now extends for about six years from near the peak of solar cycle 22, through its minimum, to the initial rise associated with solar cycle 23. Generally, the time series of UV spectral irradiances obtained shows behavior similar to that of other solar activity indices such as the F-10.7 flux. Superimposed on the Ii-year solar cycle variation is the 27-day rotational modulation which, for the most part, maintains coherence across the wavelength spectrum and also with SUSIM's own Mg II core-to-wing ratio index. However, 13.5-day periodicity is dominant for UV wavelengths between the Si I edge at 168 nm and about 300 nm for selected time periods, such as from late 1994 to mid-1995. During most of that time period, observations of solar wind velocity by experiments aboard the WIND satellite also showed predominant 13.5-day periodicity. We analyze and illustrate conditions on the sun which can in each case result in dominant 13.5-day periodicity in either measurement. We find that any combination of presence or absence of dominant 13.5-day periodicity in UV irradiance and solar wind velocity is possible depending entirely on the particular surface distribution and orientation of solar active regions.

The interplanetary propagation aspects of the first X-class solar flare and coronal mass ejection are discussed. The solar data relevant to this event are summarized. Data from WIND and charge element and isotope analysis system (CELIAS) show solar wind plasma and interplanetary magnetic field disturbances early on 12 July 1996. It was observed that the extrapolation of the coronal mass ejection back to the flare time suggests a close association between them. Moreover, the coronal mass ejection speed is similar to the type two shock's speed. The results suggest that the coronal mass ejection is intimately related to the shock itself.