Re: [ferret_users] integration from surface pressure level at each grid point

[Pratik Kad <pratikkad17@xxxxxxxxx>]

Hi Ryo

Thanks for the kind response. I tried with masking, But it does not consist when we are defining surface level. Please have a look. 

yes? list/l=1/x=83/y=28  pres, h, xyz
             Z (hPa): 0 to 1013

Column  1: PRES is Z[GZ=H]
Column  2: H is Height (m)
Column  3: XYZ is IF H GT 0 THEN H

              PRES     H      XYZ

10     /  1:    10.  29854.  29854.

30     /  2:    30.  22620.  22620.

50     /  3:    50.  19412.  19412.

70     /  4:    70.  17367.  17367.

100    /  5:   100.  15271.  15271.

150    /  6:   150.  12855.  12855.

175    /  7:   175.  11897.  11897.

200    /  8:   200.  11043.  11043.

225    /  9:   225.  10277.  10277.

250    / 10:   250.   9592.   9592.

300    / 11:   300.   8351.   8351.

350    / 12:   350.   7276.   7276.

400    / 13:   400.   6325.   6325.

450    / 14:   450.   5468.   5468.

500    / 15:   500.   4674.   4674.

550    / 16:   550.   3937.   3937.

600    / 17:   600.   3261.   3261.

650    / 18:   650.   2623.   2623.

700    / 19:   700.   2023.   2023.

750    / 20:   750.   1456.   1456.

775    / 21:   775.   1185.   1185.

800    / 22:   800.    922.    922.

825    / 23:   825.    666.    666.

850    / 24:   850.    416.    416.

875    / 25:   875.    171.    171.

900    / 26:   900.    -70.    ....

925    / 27:   925.   -311.    ....

950    / 28:   950.   -551.    ....

975    / 29:   975.   -791.    ....

1000   / 30:  1000.  -1031.    .... 

yes? list/x=83/y=28 h[z=875:10@din],xyz[z=1000:10@din]
             LONGITUDE: 83E
             LATITUDE: 28N

Column  1: H[Z=10:875@DIN] is Height (m)
Column  2: XYZ[Z=10:1000@DIN] is IF H GT 0 THEN H

                H     XYZ
I / *:     6189721.  6191862.

These two operations show different values. (Difference is -2141)

I think first we need to pinpoint surface pressure level for each grid. Then we can go for integration from that surface level. 

Best Regards

Pratik

On Sun, May 17, 2020 at 4:31 PM Ryo Furue <furue@xxxxxxxxxx> wrote:

Hi Pratik,

On Sat, May 16, 2020 at 3:42 PM Pratik Kad <pratikkad17@xxxxxxxxx> wrote:

Dear Ferret users,

I would like to take vertical integration from surface pressure level to top level. I have estimated height with respect to pressure level; I need to take surface pressure where we have a first positive value.

[ . . . ]

[ . . . ]
yes? let integrate = any_para[z=875:10@din] 

How can I define the surface pressure level at each grid point? 

You don't have to.  A better method is to "mask out" levels where height is negative:

let new_para = if H ge 0 then any_para endif

and integrate this new variable.  Then, the levels where H < 0 are automatically ignored.

Ryo