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CAM3 slab model bug on Lightning?

Hi,

John Chiang, Miren Vizcaino and I have found that a large glitch occurs in CAM3 slab model runs on Lightning around years 28 and 29. It manifests itself in the annual cycle of global mean temperature and downward solar radiation as two years in which there is only one proper winter and one proper summer. In annual means, it looks like a large downward spike in temperature.

The glitch occurs in the same year of each run, regardless of initial conditions, and under control 2xCO2, 3xCO2 and 4xCO2 conditions. I don't know if this is because the three of us have all made the same mistake in our namelist files, but they're fairly standard. Here is my control run namelist:

&camexp
absems_data = '/home/lightning/hugo/cam1/data/atm/cam/rad/abs_ems_factors_fastvx.c030508.nc'
aeroptics = '/home/lightning/hugo/cam1/data/atm/cam/rad/AerosolOptics_c040105.nc'
bndtvaer = '/home/lightning/hugo/cam1/data/atm/cam/rad/AerosolMass_V_48x96_clim_c031029.nc'
bndtvo = '/home/lightning/hugo/cam1/data/atm/cam/ozone/pcmdio3.r8.64x1_L60_clim_c970515.nc'
bndtvs = '/home/lightning/hugo/cam1/data/atm/cam/som/qflux.T31.nc'
caseid = 'control'
dtime = 1200
iyear_ad = 1950
mss_irt = 62
ncdata = '/home/lightning/hugo/cam1/data/atm/cam/inic/gaus/cami_0000-09-01_48x96_L26_c040420.nc'
nelapse = -180
nhtfrq = 0
nsrest = 0
fincl1 = 'CLDFRQ', 'CLDST', 'CNVCLD', 'LANDMCOS', 'MQ', 'SICTHK', 'SST', 'TTEND', 'UTEND', 'VTEND'
/
&clmexp
finidat = '/home/lightning/hugo/cam1/data/lnd/clm2/inidata_2.1/cam/clmi_0000-09-01_48x96_c040420.nc'
fpftcon = '/home/lightning/hugo/cam1/data/lnd/clm2/pftdata/pft-physiology'
fsurdat = '/home/lightning/hugo/cam1/data/lnd/clm2/srfdata/cam/clms_48x96_c040420.nc'
/


The bug does NOT occur in prescribed sea surface temperature runs.

I apologize if this a repost, or a well-known problem. I couldn't find it anywhere on the internet. We'd be really grateful if anyone has any advice or comments to share.

thanks,

Hugo Lambert
 
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