Re: Problem with "scale_factor"

[Joseph Mclean <mclean@xxxxxxxxxxxxx>]

Hi Jaison,

The COARDS convention states that the scale attribute be called "scale_factor"
rather than "Scale" ("add_offset" rather than "Offset").  But, it is my
understanding that per COARDS this attribute is valid for data variables but
not coordinate variables.  Editing the .cdl file and using ncgen to create a
new NetCDF file is certainly a good option.  A work-around in Ferret is to
redefine the axes.
----------------------------
let ystep=y[gy=latitude]*0.01
let xstep=x[gx=longitude]*0.01
define axis/x/from_data/name=longitude/units=degrees xstep[i=1:121]
define axis/y/from_data/name=latitude/units=degrees ystep[i=1:62]
-----------------------------

Read more about the COARDS NetCDF convention and how it applies to Ferret at
http://www.ferret.noaa.gov/noaa_coop/coop_cdf_profile.html

Hope this helps.

Joe
-------------------------------------------------------------------
Jaison Kurian wrote:

> hi all,
>          I am trying to plot a netcdf data in ferret. However the
> values of all parameters including latitude and longitude are coming
> multiplyed by 100. The header of that netcdf file contains  one "Scale"
> value of 0.01 for all parameters as shown below----
> ----------------------------------------------------
> netcdf W2990104.15P {
> dimensions:
>         latitude = 62 ;
>         longitude = 121 ;
> variables:
>         short latitude(latitude) ;
>                 latitude:Description = "latitude" ;
>                 latitude:Units = "deg" ;
>                 latitude:Scale = 0.01 ;                  <=========
>                 latitude:Offset = 0. ;
>                 latitude:Valid_max = 9000 ;
>                 latitude:Valid_min = -9000 ;
>                 latitude:_FillValue = 32767s ;
>         short longitude(longitude) ;
>                 longitude:Description = "longitude" ;
>                 longitude:Units = "deg" ;
>                 longitude:Scale = 0.01 ;                 <=========
>                 longitude:Offset = 0. ;
>                 longitude:Valid_max = 17999 ;
>                 longitude:Valid_min = -18000 ;
>                 longitude:_FillValue = 32767s ;
> ------------------------------------------------------
> the latitude and logitude values are given as
>  latitude = -3050, -2950, -2850, -2750, -2650, -2550, -2450, -2350, -2250,
>     -2150, -2050, -1950, -1850, -1750, -1650, -1550, -1450, -1350, -1250,
>     -1150, -1050, -950, -850, -750, -650, -550, -450, -350, -250, -150,
> -50,
>     50, 150, 250, 350, 450, 550, 650, 750, 850, 950, 1050, 1150, 1250,
> 1350,
>     1450, 1550, 1650, 1750, 1850, 1950, 2050, 2150, 2250, 2350, 2450,
> 2550,
>     2650, 2750, 2850, 2950, 3050 ;
>
>  longitude = 2050, 2150, 2250, 2350, 2450, 2550, 2650, 2750, 2850, 2950,
>     3050, 3150, 3250, 3350, 3450, 3550, 3650, 3750, 3850, 3950, 4050,
> 4150,
>     4250, 4350, 4450, 4550, 4650, 4750, 4850, 4950, 5050, 5150, 5250,
> 5350,
>     5450, 5550, 5650, 5750, 5850, 5950, 6050, 6150, 6250, 6350, 6450,
> 6550,
>     6650, 6750, 6850, 6950, 7050, 7150, 7250, 7350, 7450, 7550, 7650,
> 7750,
>     7850, 7950, 8050, 8150, 8250, 8350, 8450, 8550, 8650, 8750, 8850,
> 8950,
>     9050, 9150, 9250, 9350, 9450, 9550, 9650, 9750, 9850, 9950, 10050,
> 10150,
>     10250, 10350, 10450, 10550, 10650, 10750, 10850, 10950, 11050, 11150,
>     11250, 11350, 11450, 11550, 11650, 11750, 11850, 11950, 12050, 12150,
>     12250, 12350, 12450, 12550, 12650, 12750, 12850, 12950, 13050, 13150,
>     13250, 13350, 13450, 13550, 13650, 13750, 13850, 13950, 14050 ;
>
> ----------------------------------------------------------
>
> Hence it seems that the scale factor is not functioning properly. How
> can i correct it ? Does there is any other method than, correcting it in
> the cdl file and making netcdf back again ?
>
> Would appreciate any insight in this problem.
>
> Jaison

--
Joseph McLean   --------------------------------
NOAA/PMEL/TMAP   "I know what I'm doing"
(206)526-4286                     Bubba Zanetti
     -------------------------------------------