Updates to the DE/EICS pages by W.K. Peterson

• Observations of Electromagnetic Ion Cyclotron Waves During Geomagnetic Storms: Wave Occurrence and Pitch Angle Scattering, R.E. Erlandson, and A.J. Ukhorskiy, J. Geophys. Res. 106, 3883, 2001.

Other notes

Bob Erlandson wrote:
> ************************************************************
> R.E. Erlandson                 Ph: 240-228-6918(Washington)*
> JHU/Applied Physics Laboratory Ph: 443-778-6918(Baltimore) *
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> 
> Bill,
> 
> I have attached a few ps files from the EICS instrument (96s average data).
> We have found that ions get scattered into the loss cone (0-7.5 deg pa bin)
> during EMIC wave events. My question is:  Does this data look valid?  When
> the 0-7.5 deg bin registers 0 does this mean that the instrument is
> operating nominally but the count rate is just below the instrument senstivity?
> 
> Please look at the attached ps files and let me know. All cases are within
> 20 degrees of equator and aroung L=4-5.
> 
> thanks
> 

Bob,
        You ask interesting questions.  The information you want is
in the data files.  Last night I looked through the on-line documentation
in the files:
https://lasp.colorado.edu/timas/DE/DOL.html
https://lasp.colorado.edu/timas/DE/DE_eics_home.html and
https://lasp.colorado.edu/timas/DE/coverage.html#angle

I found that the documentation doesn't point you to the three parameters
in the cdf data file that is documented in the CDF skeleton file
https://lasp.colorado.edu/timas/DE/INPUT.SKELETON

What's worse, the comments in the skeleton file do not clearly tell
you where to find the answer to your question!  The pitch angle
flags described in the documentation tell you which orbits to avoid.
However these quality flags were obtained from a look at summary
spectrograms, not an interval by interval investigation of the 
data.

The answer to your question is in the three parameters
  "h_uncertainty"
  "o_uncertainty" and
  "he_uncertainty"

These arrays parallel the h_flux, o_flux, and he_flux parameters
and give the statistical uncertainty of the flux in each of the
14 angle and 15 energy bins for each 96 second interval.  The information
encoding NO SAMPLES in the 0-7.5 and 172.5-180 degree pitch angle
bins is in the uncertainty parameters.  ..... Unfortunately
I don't remember exactly how its encoded.  I'm going to have to adapt
the IDL code  https://lasp.colorado.edu/timas/DE/check_cdf.pro
to read and display the appropriate angle bins for both the flux
and uncertainty parameters for a few files to figure out how the
"no samples" information is encoded.

I'm tied up with POLAR instrument and data analysis issues for at
least the next two weeks.  I'll try to get an answer to your
question and update the DE on-line documentation to reduce
the confusion as soon as possible.  I apologize for not being
able to respond more quickly

Bill

PS: I'm putting this note in the DE pages on-line


-- 
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 W.K. (Bill) Peterson Lockheed Martin Space Sciences Laboratory         
 Temporary Address LASP  1234 Innovation Drive, Boulder CO 80303
 Ph: 303-492-0686  Fax: 303-492-6444 
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