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Structure and Dynamics in the Atmosphere Above Sunspot Regions
Kjeldseth-Moe, O.; Haugan, S. V. H.; Brekke, P. +3 more
Based on simultaneous observations of 10 EUV emission lines with the Coronal Diagnostic Spectrometer - CDS on the Solar and Heliospheric Observatory - SOHO we study the spatial distributions of both line emission and line-of-sight velocity in the atmosphere above 17 sunspots. We find that both the enhanced EUV line emissions and the velocities are…
The Dynamical and Time Variable Solar Transition Region Observed with the Coronal Diagnostic Pectrometer (CDS) on Soho
Kjeldseth-Moe, O.
CDS on SOHO has detected an upper solar atmosphere that is more dynamic and time variable than previously expected. Exciting and unexpected is the strongly time variable and dynamic active region loops at transition region temperatures. Loops in the temperature range of 1-5 × 105 K, extending 20 000 - 90 000 km above the solar surface, …
Interplanetary Disturbances Through the Minimum to the Maximum Solar Activities
Kojima, Masayoshi; Tokumaru, Munetoshi; Watanabe, Takashi
A comparative study of three-dimensional propagation properties of transient interplanetary disturbances is made for two different phases of 11-year solar activity; early ascending phase (November 1997) and the maximum phase (June 1991). These events were apparently associated with solar flares. Principal data source is solar wind speed measuremen…
The Quiet Sun Atmosphere as Seen by Soho
Keenan, F. P.; Phillips, K. J. H.; Gallagher, P. T. +2 more
The recent solar minimum has allowed studies to be made of quiet-Sun structures with SOHO instruments with better resolution than before. This paper reports on the morphology and dynamics of the EUV emission, including the chromospheric and transition-region network and coronal features, and how the photospheric magnetic field and coronal bright p…
Coronal Mass Ejections and Large Scale Structure of the Corona
Schwenn, R.; Pick, M.; Lamy, P. +3 more
A comparative study of two events accompanied by both a flare and a CME has been performed. The data analysis has been made by comparing the observations of the LASCO/SOHO coronagraphs with those of the Nancay radioheliograph. The observations show a clear connection between coronal green and red line transient activity, burst radio emission and t…
Cooling of Energetic Particles during their Transport along Spiral Field Lines
Kóta, J.
The transport of low-energy charged particles moving along magnetic field lines is considered. We point out that particles accelerated at CIRs at larger heliocentric distances and moving inward along the spiral field lose energy and decelerate even in a purely scatter free case. This results in a sizeable reduction in intensity. Scattering increas…
Dynamics of Chromiospheric and Transition Region Lines Observed with SOHO/SUMER and the GCT/Tenerife
Wilhelm, K.; Schühle, U.; Foing, B. H. +3 more
High-resolution spectroscopic observations of the quiet Sun have been carried out in September 1996 at the German Gregory Coudé Telescope (GCT) in Tenerife and in May 1997 with the SUMER instrument onboard SOHO. Time sequences of spectra in the visible and near infrared as well as in the ultraviolet have been taken, covering a range of heights fro…
Coupling Between High and Low Latitudes as Observed with Lasco in the Solar Corona and in Interplanetary Space
Schwenn, R.
From Skylab, Helios and Ulysses observations we had learnt already how closely the 3D heliosphere is related to the underlying coronal structure. Around solar activity minimum, large polar coronal holes dominate the major part of the heliosphere, through the high-speed solar wind streams emanating from them. A different type of solar wind is restr…
Dynamics in Restructuring Active Regions Observed During Soho/Yohkoh/Gbo Campaigns
Mandrini, C. H.; Nitta, N.; Fletcher, L. +6 more
JOP17 and JOP 33 are SOHO Joint Observing Programs in collaboration with Yohkoh/SXT and ground based observatories (GBO's), dedicated to observe dynamical events through the atmosphere. During runs of these programs we observed in restructuring active regions (ARs), surges, subflares, bright knots, but not large flares and jets. From these observa…
Radial Distance Dependence of the Solar Wind Speed at High Latitudes Observed by Interplanetary Scintillation
Tokumaru, M.; Kojima, M.; Yokobe, A.
We have investigated the radial distance dependence of the solar wind speed during the years 1995 and 1996 using interplanetary scintillation (IPS) observations at the Solar-Terrestrial Environment Laboratory. We derived solar wind velocity distributions for regions inside and outside of 0.3 AU separately using a computerized tomography method to …