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 asps
andp_sfc
p_sfc (
xarray.DataArray
) – The pressure at the lowest level of the model. Must be in the same units aslev
andps
ps (
xarray.DataArray
) – An array of surface pressures. Must be in the same units aslev
andp_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.