052698.etl.readme.txt

James,

This shipment contains 4 files:

1) 052698.etl.readme.txt
2) 052698.etl.iceretrievals.txt
3) 052698.etl.dmretrieval.gif
4) 052698.etl.iwcretrieval.gif

The GIF files are images of the retrieved mean diameter and IWC.
The "iceretrievals.txt" file contains the data in 4 columns:

c1) time - decimal hour
c2) height - km
c3) retrieved mean diameter - microns
c4) retrieved ice water content - mg/m3

There were two different retrievals run during this time period.

r1) Covering the time period from 20-22: coefficients derived 
from the second retrieval technique were employed here since
they could not be determined otherwise (there were no good IR 
measurements during that time).

r2) Covering the time period from 22-24: The "tuned regression"
approach was used for this retrieval.  It is considered the best
retrieval we have at the moment for this data.  It relies upon
IR measurements in order to infer the optical depth of the cloud
which gives an idea of the IWP and helps to parameterize certain
coefficients in the retrieval.  The coefficients determined during
this time period were applied to the earlier part of the cloud.  
The assumption that one can make this assignment is an uncertain
one, however, we feel that it is better than any a priori assignment
of coefficients.  The point must be made though, that the 
certainty of the retrieval is much better in the time period after
2200 than in the time period before 2200.  

We can talk more later about specifics of the retrievals.  To answer
your one question, yes we assume an exponential type DSD in our
retrievals.

If you have any questions or comments contact me.

Matthew Shupe
mshupe@etl.noaa.gov
(303)497-6471
R/ETL6 (DSRC)
325 Broadway
Boulder, CO 80303