[ferret_users] Re: finding monthly maximum in daily data [regriding problem]

[Peter Szabo <szabpet83@xxxxxxxxx>]

Hi ferreters,

one comment:
It looks proper, when i used any of the axes (now i used: 
def axis/t="15-JAN-1961":"15-DEC-2000"/np=480/edges tmonthly2) and

let prex=pre[x=@ave,y=@ave]
let premmax=prex[gt=tmonthly2@max]

instead of

let premmax=pre[x=@ave,y=@ave,gt=tmonthly2@max]

Sorry, i should have mentioned the "x=@ave,y=@ave" operations.

The given values seem to be correct (the maximum value on the attached GIF are closer to the original GIF which was posted in my latter letter), but i still dont know if the used time-axis is appropriate or not.
And i dont know why i cant use the x=@ave, y=@ave and the gt=tmonthly2@max regriding operations together.

Peter

On Tue, Nov 25, 2008 at 2:52 PM, Peter Szabo <szabpet83@xxxxxxxxx> wrote:

Dear Ferret Users,

Im totally confused about creating appropriate time-axes: i would like to get monthly maximum precipitation from daily data set.
Here are some details of my original data set:

yes? sh axis/t=1-jan-1961:3-jan-1961 tax
 name       axis              # pts   start                end
 TAX       TIME             14610 r   01-JAN-1961 00:00    31-DEC-2000 00:00
T0 = 15-JAN-1901 00:00:00
   Axis span (to cell edges) = 350640
 
       L     T                   TBOX      TBOXLO                TSTEP (HOURS)
       1>  01-JAN-1961 00:00:00  24        31-DEC-1960 12:00:00   525624
       2>  02-JAN-1961 00:00:00  24        01-JAN-1961 12:00:00   525648
       3>  03-JAN-1961 00:00:00  24        02-JAN-1961 12:00:00   525672

When i try to find the monthly maximum value through regriding to monthly data with the below command, i just cant have the correct values.

def axis/t="15-JAN-1961":"15-DEC-2000"/np=480 tmonthly
let premmax=pre[gt=tmonthly@max]

I also tried creating the time axis with "/edges" and some others also.

def axis/t="15-JAN-1961":"15-DEC-2000"/np=480/edges tmonthly
def axis/t="1-JAN-1961:00:00":"31-DEC-2000:00:00"/t0="1-JAN-1961:00:00"/np=480/edges/units=days tmonthly
etc.

None of them gave what i expected.
I enclose the original daily data set (HU_predaily.gif) and one of the plots after regriding (HU_premax_tmonthly.gif). The maximum on the original plot is 33.75 and on the others they are always bigger (around 37).

Can anyone help me?

Thanks in advance,
Peter Szabo

Attachment: HU_premax_tmonthly2.gif
Description: GIF image