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Re: [ferret_users] Problem with 6 hourly to daily average



Hi,
 
both versions of the syntax give the same result. I didn't know this.
 
yes? define axis/t="1-jan-2000:00:00":"2-jan-2000:00:00":1/unit=hours/t0="1-jan-2000:00:00" tax
 
yes? list t[gt=tax]
 
yes? define axis/t="1-jan-2000 00:00":"2-jan-2000 00:00":1/unit=hours/t0="1-jan-2000 00:00" tax
Replacing definition of axis TAX
 
yes? list t[gt=tax]
 
Sorry for the confusion,
 
Martin
 
 
On 2/9/19 9:42 PM, William Kessler wrote:
No, Satyeesh's time syntax is correct: there must be a ':' between the day and the hour in a time specification. That's why the quotes are needed; otherwise the hour would be interpreted as another argument (e.g., delta-t). I would have thought the minutes also needed to be specified but apparently not.
 
But if you want a daily average, it would be safer to define it explicitly, depending on what exactly you mean by a daily average.
If you intend it to be the mean of the values at hours 0,6,12,18, then
 
! make an explicit running 4-timestep average:
let var_daily_ave = (var+var[l=@shf:1]+var[l=@shf:2]+var[l=@shf:3])/4
 
Now subsample at hour 0:
 
define axis/t="01-jan-1993":"31-dec-2017":1/units=day t24h
let var_d = var_daily_ave[gt=t24h]
 
! check your work for an interval short enough to see what's happening:
plot/t=some_start_date:some_end_date var,var_d
 
 
 
On Feb 9, 2019, at 6:50 AM, Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx> wrote:
 
Hi,
 
seems the syntax of your times is not correct. I should be:
define axis/t="01-jan-1993 00:00":"31-dec-2017 18:00"/units=days/npoints=36524 t6
 
The same for the other axis.
Best,
Martin
Am 09.02.2019 um 15:35 schrieb Satyesh Ghetiya:
Dear all,
I am wanting to convert 6 hourly (0,6,12,18 hr) data to daily average.
 
6 hourly existing time axis, of variable var, is:
define axis/t="01-jan-1993:00:00":"31-dec-2017:18:00"/units=days/npoints=36524 t6
 
and daily time axis (on which I want my final average) is:
define axis/t="01-jan-1993:09":"31-dec-2017:09":24/units=hours t9
 
Now, following step should give my desired daily final mean:
let var_d=var[gt=t9@ave]
 
(Above method is given by the thread :../fu_2004/msg00540.html )
 
But the problem is:  var_d is not being calculated except at l=1. I have improvised all steps and all seem very fine, so var_d should give all daily values. But, except at l=1, all other l's are showing 'No Valid Data'. Any experience in this regard ?
 
Hope to hear soon.
 
Regards,
G Satyesh
 
 
 

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