1 Summary

„Space Weather refers to conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health.
- J. Freeman, 1995

The majority of solar energetic particles is thought to be accelerated at interplanetary shocks driven by coronal mass ejections.To less extend, solar energetic particles originate directly from explosive events on the Sun. The study of these particles is of importance and interestto space physics in general, but also in the context of space weather studies. The Solar and Heliospheric Observatory (SOHO) is an important tool in monitoring eruptions from the Sun that cause effects on the Earth through energetic particle radiation.

In this work we focus on five flares and associated (partial) halo coronal mass ejections during the last solar maximum, i.e. during the years 2000 and 2001. We used data of the (Highly) Suprathermal Time-OF-Flight ((H)STOF) spectrometer onboard SOHO to analyze the injection and acceleration of solar energetic particles at the shocks driven by the coronal mass ejections.

In Section 2 I give an overview of remote-optical and
in-situ particle observations during the analyzed coronal mass ejections. The effects of space weather on the terrestrial environment are breifly discussed. In Section 3 different processes at and around a strong interplanetary shock and analyzed. They energize the particles and determine their propagation. In addition we developed a model to describe the measurements. In Section 4 I report on the three suprathermal particle populations identified by (H)STOF: (1) solar wind ions, (2) interstellar pick-up He+, and (3) 3He from impulsive flares. It is discussed, how their spatial and temporal evolution near interplanetary shocks differ. Finally, in Section 5 the (H)STOF sensor as well as the data analysis are described.

2 Remote optical and in-situ particle observations of coronal mass ejections