Re: [EXTERNAL] [ferret_users] minimum range for @DIN ?

I see! By the way, do you know how to fix the @DIN cannot be applied correctly after you subtract your data from @AVE?

I need to calculate the mass transported by Hadley cells. So my v-wind must be zero when integrating through the whole column. Usually, it can be solved by subtracting the average value of v-wind. During my process of subtracting the average values, I found if you subtract the average value, pyferret does NOT treat your new values as "spatial data" (I don't know how to describe it). For example,

set data coads_climatology

let test=SST[L=8] ! just a random month

let mean=test[I=@AVE,J=@AVE]

list mean
VARIABLE : TEST[I=@AVE,J=@AVE]
FILENAME : coads_climatology.cdf
FILEPATH : /home/xbai1/miniconda2/envs/FERRET/share/fer_dsets/data/
LONGITUDE: 20E to 20E(380)
LATITUDE : 90S to 90N
TIME : 16-AUG 07:23
21.16

which means the average value is 21.16 Celsius. Then I do:

let comp1=test-mean

let comp2=test-21.16

let bad_din=comp1[I=@DIN,J=@DIN]

let good_din=comp2[I=@DIN,J=@DIN]

list bad_din, good_din
DATA SET: /home/xbai1/miniconda2/envs/FERRET/share/fer_dsets/data/ tor to a curve (x, curvey(x) ) as a function of x.

Regards,

Ryo

-------------------------------------------------

! --- script to generate the data for the plot below ---

set data coads_climatology ! grid spacing is 2°

let _ones_ = 1 + 0*y[gy=SST]

repeat/range=0:40/name=yy (let yhi=`yy/4`; let val = ones[y=0:`yhi`@DIN]; say/quiet `yhi` `val`)

Stay healthy,

Xiaoyu

On Thu, Jul 15, 2021 at 10:02 PM Ryo Furue <furue@xxxxxxxxxx> wrote:
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Dear Ferreters,

Does @DIN have a minimum range? It seems that it stops shrinking when the integration range shrinks below the gridsize.

For a test, I define a variable which is always one and print the values of the integration over y=0:ylim, where ylim = 0, 0.5, 1, 1.5, . . . .

set data coads_climatology ! grid spacing is 2°
let _ones_ = 1 + 0*y[gy=SST]
repeat/range=0:8/name=yy (let val = ones[y=0:`yy/2`@DIN]; say `val`)

I find that the value of the integral is constant when ylim

--
Xiaoyu