################################ Parameters related to time steps ################################ .. role:: bash(code) :language: bash The user must specify a number of parameters to enable CHIMERE to determine how many time steps must be used in various routines. See :doc:`CHIMERE plugin` for information on which parameters are to be provided and how this is done in the yaml. nphour ------ The number of physical time steps per hour i.e. the number of times routines such as :bash:`zenith`, :bash:`locvalues`, :bash:`physics2` are called per hour. The user provides a reference value for nphour which is called :bash:`nphour_ref` . CHIMERE then computes the actual nphour that will be used to ensure that the CFL is satisfied. For this, nphour_ref is compared to nphourm, the number of time steps per hour required to satisfy the CFL as computed by the meteo pre-processors and read in :doc:`METEO.nc`. - if nphour_ref is larger than nphourm, then nphour is taken equal to nphour_ref - if nphour_ref is smaller than nphourm, then nphour is taken equal to nphourm. See routines :bash:`checkcfl.f90, iniphys.f90, iniread.f90` for details. ichemstep --------- The number of chemical refined iterations, i.e. the number of times routines such as :bash:`twostep` is called inside a physical time step. The time step duration for an integration of the chemistry in a given hour is then dtr=3600./(nphour*ichemstep). With a chemical scheme such as MELCHIOR2 for gases: down to 1/4 degree resolution, nphour=6 and ichemstep=1 is fine; for finer grids (5-10 kms), take at least ichemstep=4; for grids of 2-5 kms, try ichemstep=6 or more. ihoursu ------- The number of hours for the spin-up. During spin-up, the number of Gauss-Seidel iterations is adapted (see nitgssu) so that computation time can be saved (see :bash:`twostep_mod.f90`). nsavedepos ---------- The cumulated depositions are saved every nsavedepos hour in the output netcdf file for depositions :doc:`dep.nc`. nitgs ----- The number of Gauss-Seidel iterations in the TWOSTEP solver outside of the spin-up (see :bash:`twostep_mod.f90` for more details). :doc:`WARNING when using the adjoint`. nitgssu ------- The number of Gauss-Seidel iterations in the TWOSTEP solver during the spin-up (see also ihoursu). hpulse ------ The hour of an emission pulse. All emissions before this hour from the beginning of the simulations are ignored, and all transport/chemistry computations are skipped. To be used when computing response functions of a given hour