Hello,
The stride syntax that you're using should be given with the
index L not the time-coordinate T, so all of the January data is
pr[L=1:480:12]
A stride using T= is acting on the underlying time units of the
time axis, which is a monthly axis but with units of days. So that
means that [T=1:480:12] is asking for data at every 12th day for
the first 480 days. The clue that I noticed was the time label at
the top of your second plot, where it's reporting that the plot
used data from the range 7-jan-1969 to 2-May 1970 .
With that change, I think the plots agree pretty well, and of
course @MOD is simplest to use.
The @MOD regridding will work with any time axis whether it
starts out as a monthly series or not, so if you started with
daily data, it gathers all of the January data for each year,
taking into account the calendar's definition of months, and
returns the climatological average; and so on for each month. It'd
also handle partial grid cells, so if the source data somehow
timesteps which don't fall exactly within the climatological
grid-cell definitions, it takes the correct portions of grid cells
to contribute to each monthly result.
Ansley
On 9/27/2018 10:37 AM, Xiaoyu Bai
wrote:
Dear ferreters,
I have a monthly rainfall .nc file which has
Gregorian calendar. I wanted to compute
climatology for each month. I tried with
"MONTH_GREGORIAN@MOD", tried with pick every month
out then take the average, "repeat/i=1:12:1 let
pr_`i`=pr[T=`i`:480:12]; repeat/i=1:12:1 let
pr_`i`_clim=pr_`i`[T=@AVE]", tried with sum them
up then divide them by the total years
"repeat/i=1:12:1 let
pr_`i`_clim_sumave=pr_`i`[T=@SUM]/40". I compared
these results and found that none of them were the
same. Any suggestions on which climatology should
I use? By the way, for the Gregorian calendar, if
I want to make the rain rates by month, is there a
better way than *60*60*24*(days of the month)?
Attach are the December climatology comparison
figures I made.
My script was as follows:
set region/X=-30:70/Y=-40:40
let pr_mod=pr[gt=MONTH_GREGORIAN@MOD]
repeat/i=1:12:1 let pr_`i`=pr[T=`i`:480:12]
repeat/i=1:12:1 let pr_`i`_clim=pr_`i`[T=@AVE]
repeat/i=1:12:1 let
pr_`i`_clim_sumave=pr_`i`[T=@SUM]/40
repeat/i=1:9:1
(contour/fill/palette=blue_darkred
(pr_`i`_clim_sumave-pr_`i`_clim)*60*60*24*30;
frame/file=0`i`_CNRM.png)
repeat/i=10:12:1
(contour/fill/palette=blue_darkred
(pr_`i`_clim_sumave-pr_`i`_clim)*60*60*24*30;
frame/file=`i`_CNRM.png)
Thank you very much. 😸
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