12 Oct
2016
12 Oct
'16
6:08 p.m.
Thanks Lukas!
I think the part that is throwing me off a bit is the "Daily NCFs were then
obtained by stacking 30-min NCFs".
This sound like to be, they took their individual 30 min NCFs and stacked
them, so that each day is represented by the stacked summation of 48
independent NCFs.
I assumed that meant that both corr_duration and analysis duration were set
to 3600, but maybe not.
I'll probably just send an email out to them to see what parameters they
used.
On Tue, Oct 11, 2016 at 11:35 PM, Lukas Preiswerk <
preiswerk(a)vaw.baug.ethz.ch> wrote:
Hi Ashton,
I can partly answer 1) and 3). First, corr_duration would be 30*60 in
their paper (corr_duration is in seconds). As far as I understand,
analysis_duration should almost always be 86400. Setting the
analysis_duration
smaller could be used to prevent loading a full day of data for
specific cases, like super high frequency data (8kHz or more). The
remaining processing still works on days and not multiples of
analysis_duration. For examplem if you set analysis_duration to 3600,
then you only use 1 hour of data each day…
Hope that helps!
Lukas
2016-10-11 18:57 GMT+02:00 Flinders, Ashton <aflinders(a)usgs.gov>ov>:
--
Ashton F. Flinders, Ph.D
U.S. Geological Survey
345 Middlefield Road
Menlo Park, CA 94025
(650) 329-5050
Hi all, I was just reading through Taka'aki
and Forents new paper using
MSNoise, and was hoping just for a wee bit more clarification on the
MSnoise processing scheme (wasnt quite clear in the docs).
The paper says;
"We first removed the instrument response from 1-day-long waveform to
obtain ground motion in displacement. Daily displacement data were
bandpassed between 0.08 and 2.0 Hz, down-sampled into 10 Hz, and split
into 30-min-long data. Those 30-min-long data were spectral whitened in a
frequency range of 0.1–0.9 Hz and then one-bit normalized. With those
one-bit normalized data, the NCFs were computed for all possible
combinations of components. Daily NCFs were then obtained by stacking
30-min NCFs."
Q1) So just in terms of implementation in msnoise admin, the 30-min-long
duration would be controlled by "analysis_duration" correct?
Q2) If you remove the instrument response, is it always removed from a 1
day chunk, or is it removed from a chunk equal in size to
"analysis_duration"? (the docs say 1 day, but I wasnt sure if this was
just
referencing the default
"analysis_duration" time).
Q3) This probably isnt the intended usage, but if you used
"analysis_duration" longer than a day, would you expect things to behave?
Thanks as always!
-ashton
p.s. paper;
http://earth-planets-space.springeropen.com/articles/10.
1186/s40623-016-0538-6
--
Ashton F. Flinders, Ph.D
U.S. Geological Survey
345 Middlefield Road
Menlo Park, CA 94025
(650) 329-5050
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