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Ellipticity, m and nppm parameters

Posted: Thu Aug 26, 2021 12:40 pm
by luigiV
Hi Marc,
I would like to submit this topic to help me in the conscious choice of the parameters m and nppm for the calculation of the right ellipticity curve.
In Deliverable D4 of the Neries-jra4 project we read in the conclusions:
"The best parameter selection for the Morlet wavelet parameter m is in the range of 4-16 with preference given to m = 8. For the number of selected wavelets per minute, nppm, we recommend using the range 5 or lower, with preference to lower values ​​as low as 1 when the recording time is sufficiently large to obtain good statistics. It is also advisable to process the data with different values ​​of nppm to identify the stable parts of the fundamental mode ellipticity curve ".
In the case that I submit to you I would like to know if the choice made is correct or not. In the first image I have the H/V curve and those of ellipticity with different values ​​of m and nppm = 10 (the time series have a duration of 1h). In the second I plotted the curve with m = 2 (which I considered the best) with 4 nppm values, from 3 to 20.
On the basis of the results I have identified that nppm = 5 is the curve to be used for the joint inversion (curve with singularity).
What is your opinion on this?
Thank you and greetings