So far when ICAR used a forcing dataset where the z-levels did not vary with time it did extrapolate some quantities downward from the lowest forcing level by keeping them constant. This could potentially lead to unwanted behavior as I’m going to show with an example in the following. I’ll refer to the ICAR version before the code modification as “ICAR old” and the version after the modification as “ICAR new”.
For a sensitivity study in a manuscript of ours that’s currently in the discussion phase at the HESS journal, we ran a couple of simulations with the Intermediate Complexity Atmospheric Research Model for the South Island of New Zealand. Horizontally the domain contained 205×225 grid points while the number of z-levels was varied between 7 and 25, corresponding to model top elevations above topography between 0.7 and 8.0 km. Here I talk a little bit about the computational performance of ICAR with regards to these simulations.