Required variables¶
Add any missing variables to fincl in user_nl_cam before running WACCM.
| Variable | Units | Description | If missing |
|---|---|---|---|
T | K | Temperature on hybrid levels | Error |
Q | kg/kg | Specific humidity | Error |
PS | Pa | Surface pressure | Error |
hyam, hybm | — | Hybrid level coefficients | Error |
P0 | Pa | Reference pressure | Warning; 100 000 Pa assumed |
O3 | mol/mol | Ozone, used in the simulation | Warning; treated as zero |
NO2 | mol/mol | NO₂, used in the simulation | Warning; treated as zero |
so4_a1, so4_a3 | kg/kg | Accumulation / coarse mode dry sulfate mass mixing ratio | Warning; the whole mode is left out of the simulation |
num_a1, num_a3 | #/kg | Accumulation / coarse mode number mixing ratio, used in the simulation | Warning; the whole mode is left out of the simulation |
dgnumwet1, dgnumwet3 | m | Accumulation / coarse mode wet median diameter, giving the particle size used in the simulation | Warning; the radius is derived from dry sulfate mass instead, which ignores water uptake |
H2O | mol/mol | Chemistry water vapour, saved with the column only | Warning; Q is used throughout |
SO2 | mol/mol | Gas-phase SO₂, saved with the column only | Warning; treated as zero |
H2O and SO2 are extracted and saved by save-inputs, but the simulator
doesn’t use them.
Example fincl addition in user_nl_cam¶
fincl1 = 'O3', 'NO2', 'H2O', 'SO2', 'so4_a1', 'so4_a3', 'num_a1', 'num_a3',
'dgnumwet1', 'dgnumwet3'MAM4 mode parameters (WACCM/BWSSP245)¶
| Mode | Suffix | σ_g | Description |
|---|---|---|---|
| Accumulation | _a1 | 1.6 | Accumulation-mode sulfate |
| Aitken | _a2 | 1.6 | Minor contribution (not used) |
| Coarse | _a3 | 1.2 | Coarse-mode sulfate |
Note: σ_g = 1.6 for the accumulation mode and σ_g = 1.2 for the coarse mode are both WACCM-specific for stratospheric sulfate (Mills et al. 2016).
VBS-SOA naming (BWSSP245)¶
Secondary organic aerosol tracers are named soa1_a1 through soa5_a1
(not soa_a1). These are not used by the ALI simulation.
H₂O blending¶
WACCM has two H₂O fields:
Q(specific humidity): well-constrained in the troposphereH2O(chemistry tracer): well-constrained in the stratosphere
cesm-hawc combines them into one water vapour profile, using Q below the
tropopause and H2O above it. The switch is centred at 100 hPa and spread
over a factor of 10 in pressure (about 316 to 32 hPa), with a smooth cosine
weighting so each field contributes half at 100 hPa.
The combined profile is saved as vmr_h2o in the files save-inputs
writes, but the simulator doesn’t use it.
References¶
Mills et al. (2016), J. Geophys. Res. Atmos., 121, 2332–2348
Liu et al. (2016), Geosci. Model Dev., 9, 505–522