set a missing value

[Christof Appenzeller <christof@xxxxxxxxxxxxxxxx>]

Hi !

I have the following problem:
I have a global data set with values over land and ocean.
I want to set a missing value over land in order to do @ave etc. over the
ocean only.
 
I can solve a part of the problem using the ferret 'default' missing
value as follows:

! interpolate etopo120 data onto my data grid 
DEFINE GRID/LIKE=TEST/T=rose[d=etopo120] era_grid

! define an ocean 
LET ocean = if rose[d=etopo120,g=era_grid] le 0 then 1

! define a new variable that has missing values over land
define variable/title="test new"/unit="bla" TEST_o if (ocean eq 1) then TEST[g=era_grid] else (-1.e+34)

However there is some problem with the missing value
when I set = -1.E34 it works fine for @ave command and for netcdf files 
when I set = 1.E35 it works fine for shade and contour commands but not for
the @ave commands. 

What do I wrong or is there a better solution or is there an other default
missing value ?
Thanks
Christof 






-- 
Dr. Christof Appenzeller			Tel.   (031) 631 48 71
Climate and Environmental Physics		Fax.   (031) 631 44 05
University of Bern
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