This review describes the infrastructure and capabilities of the expanded and upgraded Canadian Array for Realtime InvestigationS of Magnetic Activity (CARISMA) magnetometer array in the era of the THEMIS mission. Formerly operated as the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) magnetometer array until 2003, CARISMA capabilities have been extended with the deployment of additional fluxgate magnetometer stations (to a total of 28), the upgrading of the fluxgate magnetometer cadence to a standard data product of 1 sample/s (raw sampled 8 samples/s data stream available on request), and the deployment of a new network of 8 pairs of induction coils (100 samples per second). CARISMA data, GPS-timed and backed up at remote field stations, is collected using Very Small Aperture Terminal (VSAT) satellite internet in real-time providing a real-time monitor for magnetic activity on a continent-wide scale. Operating under the magnetic footprint of the THEMIS probes, data from 5 CARISMA stations at 29-30 samples/s also forms part of the formal THEMIS ground-based observatory (GBO) datastream. In addition to technical details, in this review we also outline some of the scientific capabilities of the CARISMA array for addressing all three of the scientific objectives of the THEMIS mission, namely: 1. Onset and evolution of the macroscale substorm instability, 414 I.R. Mann et al.2. Production of storm-time MeV electrons, and 3. Control of the solar wind-magnetosphere coupling by the bow shock, magnetosheath, and magnetopause. We further discuss some of the compelling questions related to these three THEMIS mission science objectives which can be addressed with CARISMA.

Magnetometer and HF radar data often indicate the presence of magnetohydrodynamic, field line resonances in the nightside magnetosphere. These resonances have frequencies of about 1.3, 1.9, 2.6, and 3.4 mHz and are due to cavity modes or waveguide modes which form between the magnetopause and turning points on dipolelike magnetic shells. Energy from these cavity modes tunnels to the field line resonances which are seen in the F region by the HF radar and on the ground by the magnetometers. The presence of these field line resonances gives us an excellent diagnostic tool for determining the position of the mechanism leading to the energetic electrons and field-aligned currents associated with substorm intensifications and auroral brightening. Using data from the Canadian CANOPUS array of magnetometers, meridian scanning photometers, riometers, and bistatic auroral radars and data from the Johns Hopkins University/Applied Physics Laboratory HF radar at Goose Bay in Canada, we have identified a number of intervals in which substorm intensifications occurred during times when field line resonances existed in the region of the magnetosphere where the intensification occurred. In the events that we have analyzed in detail, the ionospheric signatures of the substorm intensification began equatorward (earthward) of existing field line resonances. These observations give very strong evidence indicating that at least one component of the substorm mechanism must be active very close to the Earth, probably on dipolelike field lines in regions with trapped and quasi-trapped energetic particles. Furthermore, the auroral intensifications started near the position of one of the equatorward resonances, indicating that the field line resonances may play a role in triggering or producing the substorm intensifications. One possible scenario is mode conversion to kinetic Alfv6n waves in the resonance. Table 1), meridian scanning photometers, a bistatic auroral radar, and a charged couple device (CCD) imager and became fully operational in December of 1989. The CANOPUS meridian scanning photometer array (MPA) uses meridian scanning, eight-channel, filter wheel photometers at Rankin Inlet, Gillam, Pinawa, and Fort Smith. Only the data from the Gillam (GILL) and Rankin Inlet (RANK) instruments are used in this study. Five of the channels measure auroral emissions (4709, 4861 (twice), 5577, and 6300-/•), and three channels measure the background near 4800, 4935, and 6250/•. The photometer scans the meridian at two revolutions per minute with a sampling rate of 510 samples per scan per channel. Data from the scans are averaged into 17 latitudinal bins, centered on the latitude of the station. The data bins are 0.5 ø wide and 0.5 ø apart for the low-altitude (110 kin) emissions (4861, 5577, and 4709 /•) and approximately 1.0 ø wide for the high-altitude (230 kin) emission (6300/•). The magnetometer array uses three-component, ring core, flux gate instruments. Each channel is sampled at 5-s intervals. The magnetometers are aligned in geogra...

Night and early morning data from the Johns Hopkins University, Applied Physics Laboratory HF radar at Goose Bay and from the magnetometers in the Canadian CANOPUS array often show structured spectra with distinct spectral peaks at 1.3, 1.9, and 2.6 mHz. These frequencies are very stable and vary by less than ±5% for the 6 days of data we have analysed. The radar measurements of the F-region drift velocities indicate that these spectral peaks are often associated with field line resonances of the shear Alfvén wave, and that the resonances are seen at lower latitudes as the frequency increases. The magnetometer data indicate that the magnetohydrodynamic (MHD) waves have westward phase velocities. We shall show that these observations are compatible with the formation of MHD cavity modes in the early morning and nightside magnetosphere, between the magnetopause, at approximately 14.5 RE, and turning points in the dipolar magnetosphere, outside the plasmasphere. Likely sources of energy are compressional pulses from the solar wind or Kelvin–Helmholtz instabilities in the low-latitude boundary layer.

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Two-dimensional distributions of the height-integrated Pedersen and Hall conductivities have been computed for latitudes poleward of 60 ø invariant representative of two activity levels: 0 • Kp • 30 and 30 < Kp 5 9+. Average precipitating fluxes of electrons with energies of 0.15, 1.27, 9.65, and >22 keV obtained by the energetic particle detector of Isis 2 during 1971-1974 are used as input to a Rees-type computation. The assumption of equilibrium conditions and a recombination rate profile permit calcula-Method Computation of the altitude profile of the (classical) conductivity tensor elements is a straightforward process given an electron density profile. One requires only a knowledge of magnitude of the magnetic field strength and the collision-frequency profiles. Such computations have been performed extensively in the past [for example, Rowe and Mathews, 1973; Brekke et al., 1974; Vanyan and Osipova, 1975]. A model atmotion of electron density profiles and conductivity sphere is assumed, the collision frequencies are profiles. Calculations are performed at 300 grid points, specifically 12 local times and 25 latitudes from 60 ø to 84 ø invariant latitude. The models include ionization due to galactic EUV and other background sources that produces base conductivities (Zp • 0.1, Z H • 0.2 mhos) as well as solar photon ionization through an empirical fit to Chatanika radar observations [Mehta, 1979].