BGR Bundesanstalt für Geowissenschaften und Rohstoffe

Wind Dependent Spectra (Experimental page)

View precomputed wind dependent spectra for stations. Compare two sites/years via overlay or relative display.

How to use:

Night or Day Data: Two selections are possible, Night and Day+Night. Night means the spectra are computed using only daily hours between 0 and 4 and 20 to 23 (GMT), Night+Day means that data from all hours are used.

Smooth Factor: a value of 0 applies no smoothing when plotting the spectra. A value of N causes each sample to be averaged taking 2N neighbors (N before and N after the sample).

Operation: applies only when two station/year pairs are specified. overlay shows both wind dependent spectra in one plot, the first data set in a blue to red gradient, the second in gray shaded colors. relative divides the spectra of the first data set by the spectra of the second. Remember to adjust the plot scaling appropriately when changing between overlay and relative mode.

Show Numbers: if shownumbers is selected, the number of spectra used for each wind bin is shown in a separate line in the figure.

Log/Linear Display: select log or linear display on x- and y-axis. linlog means linear display on x-axis (frequency) and log scaling on y-axis (PSD), loglog means log scale on both axes. Other values accordingly.

The plots show the noise spectra in different colors from blue (low wind speeds) to red (high windspeeds) or, in an overlay display for the second data set, from light grey (low wind speeds) to dark grey (high wind speeds) in six steps (wind speed bins).

The wind speed data are taken from the ECMWF data set and are interpolated in space to each station location. The ECMWF time resolution is 6 hours. The seismogram spectra are computed in hourly segments, the spectra are assigned to the closest ECMWF wind speed bin. All spectra in a wind speed bin are averaged, spectra with exceptionally high peak values are sorted out.