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geocat.comp.interpolation._geo_height_extrapolate

geocat.comp.interpolation._geo_height_extrapolate#

geocat.comp.interpolation._geo_height_extrapolate(t_bot, lev, p_sfc, ps, phi_sfc)#

This helper function extrapolates geopotential height below ground using the ECMWF formulation described in Vertical Interpolation and Truncation of Model-Coordinate Data by Trenberth, Berry, & Buja [NCAR/TN-396, 1993]. Specifically equation 15 is used:

\[\Phi = \Phi_s - R_d T_* ln \frac{p}{p_s} \left[ 1 + \frac{1}{2}\alpha ln\frac{p}{p_s} + \frac{1}{6} \left( \alpha ln \frac{p}{p_s} \right)^2 \right]\]
Parameters:

  • t_bot (xarray.DataArray) – Temperature at the lowest (bottom) level of the model.

  • lev (int) – The pressure level of interest. Must be in the same units as ps and p_sfc

  • p_sfc (xarray.DataArray) – The pressure at the lowest level of the model. Must be in the same units as lev and ps

  • ps (xarray.DataArray) – An array of surface pressures. Must be in the same units as lev and p_sfc

  • phi_sfc – The geopotential at the lowest level of the model.

Returns:

result (xarray.DataArray) – The extrapolated geopotential height in geopotential meters at the provided pressure levels.

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