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The Swarm mission was selected as the 5th mission in ESA's Earth Explorer Programme in 2004. The mission will provide the best ever survey of the geomagnetic field and its temporal evolution that will lead to new insights into the Earth system by improving our understanding of the Earth's interior and its effect on Geospace, the vast region around the Earth where electrodynamic processes are influenced by the Earth's magnetic field. Scheduled for launch in 2010, the mission will comprise a constellation of three satellites, with two spacecraft flying sideby-side at lower altitude (450 km initial altitude), thereby measuring the East-West gradient of the magnetic field, and the third one flying at higher altitude (530 km). High-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements, will provide the necessary observations that are required to separate and model the various sources of the geomagnetic field. This results in a unique "view" inside the Earth from space to study the composition and processes of its interior. It also allows analysing the Sun's influence within the Earth system. In addition practical applications in many different areas, such as space weather, radiation hazards, navigation and resource management, will benefit from the Swarm concept.

It has recently been suggested that the solar irradiance has varied in phase with the 80- to 90-year period represented by the envelope of the 11-year sunspot cycle and that this variation is causing a significant part of the changes in the global temperature. This interpretation has been criticized for statistical reasons and because there are no observations that indicate significant changes in the solar irradiance. A set of data that supports the suggestion of a direct influence of solar activity on global climate is the variation of the solar cycle length. This record closely matches the long-term variations of the Northern Hemisphere land air temperature during the past 130 years.

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Abstract.We have studied the onset timing of earthward high-speed ion flow observed by the AMPTE/IRM satellite at 12.3 Earth radii (RE) and 0100 MLT in the central plasma sheet during an isolated substorm event on March 1, 1985. The timing of this onset is compared with that of the substorm current wedge and Pi 2 magnetic pulsations observed by a large number of ground-based stations and the AMPTE/CCE, GOES 5, and ISEE 1 satellites and with that of high-energy particle injection observed at Los Aimos geosynchronous satellite 1982-019. The onset of earthward high-speed flow is observed 3 min before the onset of the global current wedge formation and 6 min before the onset of high-energy particle injection. The three bursts of the high-speed flow observed at AMPTE/IRM are likely to correspond to three compressional pulses observed at AMPTE/CCE at 6 RE and three Pi 2 wave packets observed at midlatitude ground stations. On the basis of these observations we conclude that the substorm current wedge is caused by inertia current and the current due to flow shear at the braking point of the earthward high-speed flow during the initial stage of the substorm expansion phase. The braking point is well separated from the near-Earth neutral line. It is also suggested that the compressional pulses and fluctuations of field-aligned currents generated at the flow braking point can be the initial cause of the Pi 2 magnetic pulsations in the inner magnetosphere.

Analysis of 20‐second resolution magnetometer data from an array of temporary stations operated around Søndre Strømfjord, Greenland during the summer of 1986 shows the signatures of localized ionospheric traveling convection vortices. An example of an isolated event of this kind observed near 08 local time is presented in detail. This event consists of a twin vortex pattern of convection consistent with the presence of two field‐aligned current filaments separated by about 600 km in the east‐west direction. This system of currents is observed to move westward (tailward) past the array of stations at about 4 km/sec. The event is associated with relative quiet time ionospheric convection and occurs during an interval of northward IMF. It is, however, associated with a large fluctuation in both the Z and Y components of the IMF and with a large sudden decrease in the solar wind number density. The propagation of the system is inconsistent with existing models of FTE current systems, but nevertheless appears to be related to a readjustment of the magnetopause boundary to a sudden change in the solar wind dynamic pressure and/or to a change in reconnection brought about by a sudden reorientation of the IMF.

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