CM1 capability on nudging to a time evolving domain mean sounding

[vargasmartes]

We are interested in nudging the CM1 simulation to a time-evolving domain-mean sounding (every 3 hours), to compare this with simulations from the gSam model. Is this something that can be done with CM1?

Could you provide some insight on how to best approach this? We have been playing around with the model but have not found a straight way to go about this.

I would appreciate any insights you may provide.

 

[ahijevyc]

There may be some nudging help in the namelist README under parameter 19:

param19 section: Options related to large-scale (i.e., domain-average) nudging.

(for details, see Appendix of Alland et al. 2021, doi:10.1175/JAS-D-20-0054.1)


! use large-scale wind nudging?

do_lsnudge - use large-scale nudging? (T/F)

! Note: see the documentation at the top of lsnudge.F for some important info


! for do_lsnudge=.true., select which variables are nudged:

do_lsnudge_u - nudge domain-avg u wind profile?
do_lsnudge_v - nudge domain-avg v wind profile?
do_lsnudge_th - nudge domain-avg potential temperature (theta) profile?
do_lsnudge_qv - nudge domain-avg water vapor mixing ratio (qv) profile?



lsnudge_tau - time scale (seconds) for damping term


! NOTE: CM1 only applies large-scale nudging when t > lsnudge_start and
! t < lsnudge_end; the user must set these two variables below.
! For any other times, large-scale nudging is not applied, regardless
! of the times provided for lsnudge_time1 and lsnudge_time2 in the
! lsnudge_xxxx.dat files.

lsnudge_start - time (seconds) to begin large-scale nudging

lsnudge_end - time (seconds) to end large-scale nudging

lsnudge_ramp_time - time (seconds) over which to gradually introduce
nudging; that is, for
lsnudge_start < t (seconds) < lsnudge_start+nudge_ramp_time

Nudging term is linearly increased from 0 to full nudging term
over this time period.

(set lsnudge_ramp_time to zero for instantaneous introduction of nudging)