Substepping for heat flux (record for future revisit) #200
Description
Description:
Keeping a record of the discussion on adding substepping for heat flux handling in shallow water cells.
Idea:
target thin-water cells flagged by hmin_airsea_ex or by detecting large per-step temperature jumps.
Within substeps, call the bulk aerodynamic routine (sflux_9c_.F90) so sensible, latent, and upward longwave fluxes respond to evolving surface temperature. Shortwave remains fixed at the main step.
Substep size could be determined by a predefined threshold for heat flux or temperature increment.
Purpose: acts as a numerical stabilizer, preventing stepwise blow-ups. It complements, but does not replace, the physical buffer (sediment conduction, etc.). Substepping also helps sensible/latent fluxes adjust smoothly without artificial swings.
Effect and performance cost still need to be tested in real cases.