Computer session on measurement and analysis of waves and turbulence

6th COSPAR Capacity Building Workshop

Sinaia, Romania, June 4-16, 2007

Ondrej Santolik


Programming exercise: Multidimensional analysis of waveforms

The Hermitian spectral matrix is used as input data of many analysis methods. It is obtained using multidimensional spectral analysis of several input waveforms. These waveform signals can be, for example, the three components of the magnetic field fluctuations. Each signal is first subjected to the Fourier analysis. At a given frequency, we calculate the element Sij of the spectral matrix as a time-averaged product of the complex amplitude of the ith signal with the complex conjugate of the complex amplitude of the jth signal:

Instructions:

  1. Download the following IDL procedures:
  2. Read the comments and try to understand the code (the above sequence of files is recommended)
  3. Write a new IDL program to estimate spectral matrices from the three component waveforms of the magnetic field fluctuations.
  4. Run the program using the data sets whistlers_waveform_f4x, whistlers_waveform_f4y, and whistlers_waveform_f4z.
  5. Re-run the analysis methods based on spectral matrices using the results.

Reading: The ISSI book, Chapter 1.5