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



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.


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