GFS and IFS are both medium-range global models in the class Google is targeting. These models are spectral models, meaning they pivot the input spatial grid into the frequency domain, carry out weather computations in the frequency domain, and pivot back to provide output grids.
The intuition here is that, at global scale over many days, the primary dynamics are waves doing what waves do. Representing state in terms of waves reduces the accumulation of numerical errors. On the other hand, this only works on spheroids and it comes at the expense of greatly complicating local interactions, so the use of spectral methods for NWP is far from universal.
GFS and IFS are both medium-range global models in the class Google is targeting. These models are spectral models, meaning they pivot the input spatial grid into the frequency domain, carry out weather computations in the frequency domain, and pivot back to provide output grids.
The intuition here is that, at global scale over many days, the primary dynamics are waves doing what waves do. Representing state in terms of waves reduces the accumulation of numerical errors. On the other hand, this only works on spheroids and it comes at the expense of greatly complicating local interactions, so the use of spectral methods for NWP is far from universal.