Fig. 2: Frequency-domain characteristics of sols 422 and 423 SEIS data.

a Vertical-component spectrogram of sols 422 and 423. Typically, mornings and afternoons show high levels of wind-induced noise, while evenings and nights are characterized by significantly lower ambient noise levels due to largely absent local winds. Note the lander-related modes (e.g., at 1.6, 3.3, 4.1, 6.8 Hz) that show a time-dependent change of their resonance frequencies. The lander-related modes correlate with the wind activity, suggesting that winds shaking the lander are the cause of these resonances. b H/V ratio for the same data as in (a). During quiet time intervals such as in the evening hours, the ambient vibration power spectrum is relatively flat with the prominent exception of a distinct H/V trough at around 2.4 Hz. (right) Three H/V curves extracted for two windy and one quiet period of sols 422/423. The orange curve corresponds to the steady morning wind time window, the green curve to the turbulent afternoon time window and the red curve to the quiet evening time window (see colored bars marking the time windows).