[ncl-talk] question regarding Butterworth filter

[Daniel Barandiaran]

Hi everyone,

I was trying out the bw_bandpass_filter function and found some unexpected
results. The gist of the problem is that the end of the time series being
filtered approaches a smoothed zero, even if the time series is doing
something else entirely (see attached figure, consider bold blue line and
shaded blue area). I imagine this is due to the internal workings of the
filter itself, but regardless of that, does anyone have any ideas on
"fixing" this?

Some details: I have fca set to 1/60., or 5 years, and fcb set arbitrarily
large, i.e. 1/100000., so the filter essentially behaves as low pass. I am
also making sure to not give the function any missing values.


--
Danny Barandiaran
Ph.D. Candidate
Department of Plants, Soils, and Climate
Utah State University
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