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[GEMPAK #KTU-213331]: Radar NTP/BRET threshold values

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  • Subject: [GEMPAK #KTU-213331]: Radar NTP/BRET threshold values
  • Date: Thu, 27 Jun 2013 09:46:12 -0600
Hi Jim,

The program NEX2GINI uses a file nex2gini.tbl which is viewable here:
https://github.com/Unidata/gempak/blob/master/gempak/tables/unidata/nex2gini.tbl

It contains a line for NTP with three groups of precip <=> pixel equivalence:

!Prod   band ncal units,Calval_1;....;calval_n  Prod_header
NTP       31    3 inches,10,110,0,4;110,220,4,12;210,255,12,24     TICZ99 CHIZ

this entry translates to:

* three calibration ranges
* units in inches
* 0-4 inches = 10-110
* 4-12 inches = 110-220
* 12-24 inches = 210-255

So precipitation values can be determined by linearly interpolating values 
between the min/max of these three ranges. 


-Michael


> Michael,
> 
> I can understand the way individual sites report may vary and you use a 
> floating scale to standardize the colors for a given amount of precipitation, 
> but in the composite BRET file aren't the standardized values sent in the 
> composite. My thinking was that the BRET composite file was built into 
> something like a satellite IR image file, which has brightness values 
> corresponding to certain temperatures and that for NTP, the image 
> "brightness" values correspond to certain values, which are reflected in the 
> color bar that I see on the McIDAS display of the BRET files (e.g. the color 
> bar is always the same and always corresponds to the listed values). Am I 
> incorrect to assume that the BRET values should correspond to certain 
> precipitation values. Otherwise, I don't see how McIDAS could always use the 
> same color bar/values.
> 
> Jim

Ticket Details
===================
Ticket ID: KTU-213331
Department: Support GEMPAK
Priority: Normal
Status: Open