pl_to_hl

pl_to_hl(fs, z, zs, h, ref_level, method)

New in Metview version 5.23.0

Interpolate fs on pressure levels onto height levels (in m) above sea or ground level.

Parameters

  • fs (Fieldset) – fieldset to be interpolated. There is no restriction on the order or range of pressure levels in fs.

  • z (Fieldset) – geopotential fieldset on pressure levels (it must contain the same levels as fs but their order can be different)

  • zs (Fieldset or None) – surface geopotential field (if ref_level is set to “sea” it should be set to None).

  • h (list or Fieldset) – list of target height levels in metres above/below the ref_level (they can came in any given order)

  • ref_level (str) – specify the reference level for the target heights. The possible values are “sea” and “ground”. If it is “ground” a valid zs must be provided.

  • method (str) – specify the interpolation method. The possible values are “linear” and “log”. For target height levels very close to 0 always a “linear” interpolation is used.

Return type

Fieldset

The input data (fs) must contain one field per pressure level only. It means that e.g. data containing multiple timesteps cannot be used as an input.

At gridpoints where the interpolation is not possible a missing value is returned. It happens where the target height level is below the bottom-most pressure level in fs. It also happens where the target height is above the top-most pressure level in fs.

Note

See also mvl_ml2hPa(), pl_to_hl().

Example

This code illustrates how to use pl_to_hl() with data retrieved from MARS:

import metview as mv

# retrieve the data on model levels - surface geopotential (zs)
# is taken from the analyis on level 1!
ret_core = {
   "levtype": "pl", "date": 20191023, "time": 12 "grid": [2,2]}

fs_pl = mv.retrieve(**ret_core,
         type="fc",
         levelist=[1000,925,850,700,500,300,250,200,150,100],
         step=12,
         param=["t", "z"])

t = mv.read(data=fs_ml, param="t")
z = mv.read(data=fs_ml, param="z")

zs = mv.retrieve(**ret_core,
      type="an",
      levelist="sfc",
      param="z")

# interpolate the t field onto a list of height levels above sea level
hlevs = [1000, 2000, 3000, 4000, 5000]
th_sea = mv.pl_to_hl (t, z, None, hlevs, "sea", "linear")


# interpolate the t field onto another list of height levels above ground
hlevs = [100, 200, 300, 400, 500]
th_ground = mv.pl_to_hl (t, z, zs, hlevs, "ground", "linear")