Fig. 2

Energy spectra in the wavenumber-frequency domain spanned by wavenumber along the flow and frequency in the spacecraft frame. Panel (a) is the spectrum derived from magnetic field data of Cluster, in the time intervals shown in Fig. 1, using the high-resolution wavenumber analysis technique MSR. The panel (b) shows the best-fitted spectrum for the parameter set determined by the method of least square estimator (cf. Fig. 3). Contour levels are given in units of nT²/[(rad/s)(rad/km)].