I want to use the multifractal cascades model to do a 3D downscaling of the radar rainfall products into finer spatial and temporal resolutions. However, the radar data I am using (NEXRAD in the US) have variable time steps (sometimes 5 mins, sometimes 4 or 6 mins), while the multifractal cascades model (Gires et al., 2012) requires the data to have fixed time steps. 

Does anyone know how to use multifractal cascades model or any other model to stochastically downscale the radar data into finer spatial and temporal scales? Any website or paper would be helpful.

Gires et al., 2012. Quantifying the impact of small scale unmeasured rainfall variability on urban runoff through multifractal downscaling: A case study