How to properly interpolate wind speeds to a specific height above ground level?

[akumler]

Hello,

I am working with ARISE-SAI-1.5 and CESM2-WACCM6-SSP245 model output, and I would like to calculate the wind speed above ground level, specifically 100 m. Besides the 10 m wind speed variable that is readily available, zonal (U) and meridional (V) winds are available on model levels (lev), which I know are sigma-pressure hybrid levels.

So far, I have tried calculating wind speeds at 100 m by first calculating the heights that the model levels are at for each point in time, taking surface geopotential (PHIS) and dividing by gravity to get heights, then subtracting these heights from geopotential heights (Z3) to get model levels heights above the surface. Since I only need data at 100 m, geopotential heights should be roughly equivalent to geometric heights. When I do this, and calculate wind speeds from U and V, and interpolate wind speeds using the power law equation, I get wind speeds that are actually lower than the mean 10 m wind speed outputs globally, which should not be happening.

Am I missing something? Am I using the wrong variables to calculate model heights? Do I need to leverage a more specific equation to obtain wind speeds at 100 m?

Thanks!

 

[tking]

Hi Andrew, You may want to check out the interp_hybrid_to_pressure function from GeoCAT. This is specifically designed to interpolate data from hybrid-sigma levels to isobaric levels.

 

[akumler]

Hi Andrew, You may want to check out the interp_hybrid_to_pressure function from GeoCAT. This is specifically designed to interpolate data from hybrid-sigma levels to isobaric levels.

Ah yes, this looks like it will work! Thank you!