NOTE: Negative values at start of time axis

[Jörg Kaduk <joerg@xxxxxxxxxxxxxxxxxxx>]

Hi everybody,

I get a note from ferret which confuses me a bit. ferret complains
about negative time values - see NOTE below.
However, my time data start with 0. I've pasted the output from
ferret and stuff from the netcdf file below.
Could it be that the fact that I use a negative missing value 
for the time variable confuses ferret?

I could not detect a real problem so far, but if I start thinking 
about averaging and alike a wrong time axis would make me uneasy.

Thanks everybody for your time and efforts!

Cheers!
Joerg



Output from ferret:

cecropia.Stanford.EDU(177): !f
ferret
appending ferret path
        NOAA/PMEL TMAP
        Program FERRET (GUI)
        Version 4.91 - 05/19/98
        16-Nov-98 22:32     
 
yes? use eragrdmon_197901.nc
 *** NOTE: Negative values at start of time axis may be improperly
formatted: eragrdmon_197901.nc


Output from ncdump:

/opt/netcdf-3.3.1/bin/ncdump eragrdmon_197901.nc | m
netcdf eragrdmon_197901 {
dimensions:
        longitude = 320 ;
        latitude = 160 ;
        latitude_edges = 161 ;
        time = UNLIMITED ; // (5 currently)
variables:

....
        float time(time) ;
                time:Grib_code = 1 ;
                time:long_name =
"Time                                          
                                  " ;
                time:units = "sec since 1979-01-01 00:00:00 " ;
                time:point_spacing =
"even                                      
                                      " ;
                time:valid_min = 0.f ;
                time:valid_max = 4.294967e+09f ;
                time:missing_value = -1.e+34f ;
                time:_FillValue = -1.e+34f ;

...

 time = 0, 21600, 43200, 64800, 86400 ;


--
Jörg Kaduk                              Tel.: 1 650 325 1521 x 416
Carnegie Institution of Washington      FAX: 1 650 325 6857
Dept. of Plant Biology
260 Panama Street                       joerg@jasper.stanford.edu
Stanford, CA 94305-1297                
http://Jasper.Stanford.EDU/joerg/