Re: [ferret_users] vertical levels shifts after apply @DIN

[Xiaoyu Bai <xbai1@xxxxxxxx>]

Dear Ansley,

I think I got it. Looks like to me, ferret "puts" an extra layer between my vertical levels and gave two extra layers to both ends (top and surface of the atmosphere) to do the integration. Say a 550 hPa between 500 and 600 hPa. Thus, the K=1 @DIN starts from 5 hPa instead of 10 hPa and K=17 @DIN became 1032.5 hPa instead of 1000 hPa.

Thank you very much and stay healthy,

Xiaoyu

On Thu, Jun 11, 2020 at 5:15 PM Ansley C. Manke <ansley.b.manke@xxxxxxxx> wrote:

Hi,
Sometimes defining a very simple variable and applying the
transformation to it is helpful.  Do the integration operations on a
variable like this

   let constant_var = 1 + 0*test

to see if it helps you understand what may be happening.  Also looking
at the indefinite integral of both your original variables and this
simple one might be useful.

As you may know, transformations such as the definite integral always
take the grid-cell sizes into account.  This is described in detail
here, "General Information about Transformations",
https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/variables-xpressions/XPRESSIONS#GeneralInfo

I wonder if there is something particular in the definition of the grid
cells in Z that makes the computations inconsistent.

Ansley

On 6/10/2020 6:48 PM, Xiaoyu Bai wrote:
> Dear ferreters,
>
> I have 17 levels of v-wind data.
>
> list/j=82/l=6 va_4CO2_MPAS_monthly_ave
>              VARIABLE : VA_4CO2_MPAS_MONTHLY[X=@AVE]
>              SUBSET   : 17 points (Z (Pa))
>              LONGITUDE: 1.2W(-1.2) to 1.2W
>              LATITUDE : 63.5N
>              TIME     : 16-JUN 00:00 NOLEAP
>  1000     /  1: -0.0394
>  2000     /  2: -0.0227
>  3000     /  3: -0.0209
>  5000     /  4: -0.0252
>  7000     /  5: -0.0219
>  10000    /  6: -0.0125
>  15000    /  7:  0.0496
>  20000    /  8:  0.1512
>  25000    /  9:  0.1367
>  30000    / 10:  0.0665
>  40000    / 11:  0.0014
>  50000    / 12: -0.0065
>  60000    / 13: -0.0048
>  70000    / 14: -0.0037
>  85000    / 15: -0.0020
>  92500    / 16:  0.0645
>  100000   / 17:  0.2435
> I corrected the noise of it first and then applied @DIN for the
> vertical levels.
> list/j=82/l=6 test
>              VARIABLE : VA_4CO2_MPAS_MONTHLY_AVE-0.03951
>              SUBSET   : 17 points (Z (Pa))
>              LONGITUDE: 1.2W(-1.2) to 1.2W
>              LATITUDE : 63.5N
>              TIME     : 16-JUN 00:00 NOLEAP
>  1000     /  1: -0.0789
>  2000     /  2: -0.0622
>  3000     /  3: -0.0605
>  5000     /  4: -0.0647
>  7000     /  5: -0.0614
>  10000    /  6: -0.0520
>  15000    /  7:  0.0101
>  20000    /  8:  0.1117
>  25000    /  9:  0.0971
>  30000    / 10:  0.0270
>  40000    / 11: -0.0381
>  50000    / 12: -0.0460
>  60000    / 13: -0.0443
>  70000    / 14: -0.0433
>  85000    / 15: -0.0415
>  92500    / 16:  0.0250
>  100000   / 17:  0.2040
> When I listed out the results I found that the vertical levels shifted
> 50 Pa comparing to the original data:
> list/j=82/l=6 test_re, test_up, test_down2
>              LONGITUDE: 1.2W(-1.2) to 1.2W
>              LATITUDE: 63.5N
>              TIME: 16-JUN 00:00 NOLEAP
>  Column  1: TEST_RE[Z=500:103750] is TEST[K=1:17@DIN]/9.8
>  Column  2: TEST_UP[Z=500:55000] is TEST[K=1:12@DIN]/9.8
>  Column  3: TEST_DOWN2[Z=55000:103750] is TEST[K=13:17@DIN]/9.8
>           TEST_RE  TEST_UP TEST_DOWN2
> I / *:     0.04177  -27.18   27.22
> Is there a reason for it?
>
> Thank you in advance.
> --
> Xiaoyu

--
Ansley Manke
Science Data Integration Group
NOAA Pacific Marine Environmental Laboratory
7600 Sand Point Way NE
Seattle WA 98115

I am currently teleworking and am available Tue-Wed-Thu.

--

Xiaoyu