Lanczos Filtering (low, high, band)

I have been looked for filtering at NCL(+), Fortran, GrADS…

however, Ferret has it !!!

 

(1) LANCZOS

(2) LSL_LOWPASS

 

Example>

low pass filtering (>10 month), take the frequency more than 10 month.

yes? use monthly_navy_winds

yes? plot lanczos(uwnd, 0.1,0,11) !black line in figure

yes? plot/o lsl_lowpass(uwnd,10,11) !red line in figure

filtering

So, Simple 🙂