esccr oddities

From: Derrick Snowden (Derrick.Snowden AT noaa.gov)
Date: Mon Feb 21 2005 - 15:58:57 MST


Hi all,

I'm trying to plot a map of correlation between two fields which I generated
using esccr. I usually insert the line below in my plotting scripts to get a
feel for the range of the variables in the map.

res@cnInfoLabelOn = True
res@cnInfoLabelString = "min = $ZMN$, max = $ZMX$"

Recently, I generated some plots with values larger than one and smaller than
minus one. I'm using time series that have 108 points in them and am only
looking at lags out to two or three so I don't anticipate any strange
statistical problems. In the plots I set the contour min/max/cint
explicitly. If I repeat the calculation and insert a line to mask values
greater than one...

ccr = mask(ccr,ccr.gt.1.0,False)

The resultant plot looks, to my eye, identical. Both variables have the
_FillValue attribute set. But, occasionally I notice trouble with fill
values in files generated by different applications or originally stored as
doubles but coerced to floats. Could a few outliers in the data which are
near but not equal to a very large fill value cause this behavior? (i.e.
_FillValue = -9.99e34 and a data point has a value -9.9892342392e34.) I
suppose this could be the result of using linint2 to regrid the variables
prior to the correlation calculation. This is ocean model data and those
*$^@ coastlines make things difficult sometimes.

I suppose I've answered my own question but if anyone has comments....

Best,
Derrick

-- 
Derrick Snowden
PhOD/AOML/NOAA
4301 Rickenbacker Causeway
Miami, FL 33149
Office: 305.361.4322  Fax: 305.361.4392
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