Methodology:

The plasma wave data used in this study come from Dynamics Explorer 1 (DE1), Cluster 1, Double Star TC1, THEMIS-A, THEMIS-D, THEMIS-E, RBSP-A and RBSP-B. The DE1 wave data are available from the CDAWeb (https://cdaweb.sci.gsfc.nasa.gov/index.html/). The Cluster and Double Star TC1 data are available at the Cluster Science Archive (https://www.cosmos.esa.int/web/csa). The THEMIS data is available from http://themis.ssl.berkeley.edu/data/themis/. The Van Allen Probes plasma wave data are available at https://emfisis.physics.uiowa.edu/data/index. The AE indices used in this study are available from the NSSDC Omniweb. Full details of the subsequent analysis are given in Meredith et al. [2021].

Data collection:

We use data from the Plasma Wave Instrument on DE1, the STAFF instruments on Cluster 1 and Double Star TC1, the Search Coil Magnetometers on THEMIS -A, -D and -E and the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instruments on board RBSP-A and RBSP-B.

The Plasma Wave Instrument on DE1 measured one component of the magnetic field in the frequency range between 1.78 Hz and 410 kHz. The SFC Step Frequency Correlator, composed of two Step Frequency Receivers, provided the spectral density of the magnetic field coming from 128 frequency channels, logarithmically spaced between 105 Hz and 410 kHz.

The STAFF experiment on Cluster 1 consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, a waveform unit (up to either 10 Hz or 180 Hz) and a Spectrum Analyser (up to 4 kHz). The Spectrum Analyser combines the 3 magnetic components of the waves with the two electric components measured by the Electric Fields and Waves experiment (EFW) to calculate in real time the 5 x 5 Hermitian cross-spectral matrix at 27 frequencies distributed logarithmically in the frequency range 8 Hz to 4 kHz.

The STAFF experiment on Double Star TC1 consisted of a search coil antenna, three pre-amplifiers, a magnetic waveform unit, and power supply provided by CETP, and a Digital Wave Processor (DWP) provided by the University of Sheffield. The DWP computed the spectral matrix (3 power spectra plus the cross phase between each component) at 27 frequencies between 8 Hz and 4 kHz.

The Search Coil Magnetometers on THEMIS-A, -D and -E measure magnetic field fluctuations in the frequency range from 0.1 Hz to 4 kHz. The high resolution (fff) data used here consists of measurements of one component of the magnetic wave spectral density in the spacecraft spin plane, with a frequency resolution with 32 or 64 frequency bands logarithmically spaced over 4-4000 Hz.

The EMFISIS Waveform Receivers on RBSP-A and RBSP-B measured the sum of the three components of the magnetic power spectral density of the waves in 65 frequency channels, with centre frequencies between 2.13 Hz and 11.24 kHz.

Data quality:

The wave data have been calibrated and quality-controlled prior to release.