Re: Spectrum question

Helen

For your purposes, I would suggest that the function 'fourier_info' would probably be more appropriate.

Assuming tat you input data has the dimensions (/altitude, time/) then the fourier_info function will return an array dimensioned four= (component, harmonic, altitude). In this case, you want to plot the 'amplitude' component (i.e. the first element of the left most dimension), so you will have a 2-d array where the 'harmonic' dimension represents the frequency; you should not need to use phase scaling.

The NCL manual entry on 'fourier _info' includes information on how to use the function, and how to scale the harmonic term into a frequency as appropriate.

http://www.ncl.ucar.edu/Document/Functions/Built-in/fourier_info.shtml

Hope that helps

Will

On 11/8/10 6:08 PM, "Helen Parish" <hparish@ess.ucla.edu> wrote:

I am still looking for an answer to the question I submitted last week
about plotting a contour of the magnitude of a spectrum as a function
of frequency and altitude at constant latitude (and also as a function
of frequency and latitude at constant altitude). I show an example of
the type of plot I wish to produce below. I have used routine
"specx_anal", but this only produces a line graph. Can I do this in
NCL or not, and if so how ?.

Thanks,
Helen.

**********************************************************
Will Hobbs, Ph.D. William.R.Hobbs@jpl.nasa.gov
Jet Propulsion Laboratory
4800 Oak Grove Dr. office: 300-324a
M/S 300-323 phone: (818) 354-0466
Pasadena, CA 91109 fax: (818) 354-0966
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Received on Mon Nov 8 18:28:17 2010