More engineering fixes required for the CICE initialization

[guillaumevernieres]

Description

There are a few more cases for which the CICE model forecast becomes unstable.

Solution

Something needs to be done about snow enthalpy and small sea-ice concentration values. Solution from Philip Pegion:

1. Removal of small sea-ice

import xarray as xr
import numpy as np
import sys
import shutil

infile=sys.argv[1]
ds_in=xr.open_dataset(infile)

var_list=['vicen','vsnon','Tsfcn','iage','alvl','vlvl', 'apnd', 'hpnd', 'ipnd',\
 'dhs', 'ffrac', 'sice001', 'qice001', 'sice002', 'qice002', 'sice003', 'qice003',\
 'sice004', 'qice004', 'sice005', 'qice005', 'sice006', 'qice006', 'sice007', 'qice007','qsno001','aicen']
for var in var_list:
    tmparr=np.where(ds_in['aicen'].values >0.15,ds_in[var],0.0)
    ds_in[var][:]=tmparr

new_frac=tmparr.sum(axis=0)
new_mask=np.where(new_frac > 0, 1.0,0.0)
ds_in['iceumask'][:]=new_mask
ds_in.to_netcdf('trimmed_'+infile)
ds_in.close()
shutil.move(infile,'old_'+infile)
shutil.move('trimmed_'+infile,infile)

2. Limit snow enthalpy

   
   import xarray as xr
   import numpy as np
   import sys

infile=sys.argv[1] anl=xr.opendataset('anl'+infile) rhos = 330.0 cp_ice = 2106. c1 = 1.0 Lsub = 2.835e6 Lvap = 2.501e6 Lfresh=Lsub - Lvap rnslyr=1.0 puny=1.0E-012

icepack formulate for snow temperature

A = c1 / (rhos cp_ice) B = Lfresh / cp_ice zTsn = A anl['qsno001'][:].values + B

icepack formula for max snow tempature

Tmax = -anl['qsno001'][:].valuespunyrnslyr /(rhoscp_iceanl['vsnon'][:].values)

enthlap at max now tempetarure

Qmax=rhoscp_ice(Tmax-Lfresh/cp_ice)

fill in new enthalpy where snow temperature is too high

newq=np.where(zTsn <= Tmax,anl['qsno001'][:].values,Qmax) newf=np.where(anl['vicen'] > 0.00001,anl['aicen'][:].values,0.0)

fill in snow enthalpy (0) where there is no snow

newq2=np.where(anl['vsnon'][:]==0.0,anl['qsno001'][:].values,newq) anl['qsno001'][:]=newq2 anl['aicen'][:]=newf

write out file

anl.to_netcdf(infile)

The above features need to be added to the `soca2cice` var change.

[ShastriPaturi]

Thanks for sharing @guillaumevernieres