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CHAPTER 3. PREPROCESSING
Note that initial conditions for Castor are interpolated from the boundary conditions and
do not need to be computed separately.
3.8.3
Boundary Conditions for Aerosol Species: bc-gocart
Boundary conditions for aerosol species are obtained using Gocart model†1 thanks to the program
bc-gocart.
Gocart format and conventions
Gocart model usually provides files with the following naming convention:
file name
yyyymm.XX.vs.g
yyyymm.XX.vs.g.day
yyyymm.XX.vs.g.avg
signification
6-hourly concentrations in g m−3 .
daily averaged concentrations in g m−3 .
monthly averaged concentrations in g m−3 .
where yyyymm is the year and month (e.g., 200103), XX is the Gocart species, which can
be either SU (sulfur), CC (carbonaceous), DU (dust), SS (sea-salt), and vs is the version (e.g.,
STD.tv12).
Gocart species may have further speciations:
• SU (sulfur): Total 4, 1-DMS, 2-SO2, 3-SO4, 4-MSA.
• CC (BC+OC): Total 4, 1-hydrophobic BC, 2-hydrophobic OC, 3-hydrophilic BC, 4hydrophilic OC.
• DU (dust): Total 5, 1-Re=0.1-1, 2-Re=1-1.8, 3-Re=1.8-3, 4-Re=3-6, 5-Re=6-10 µm. The
first group (0.1-1 µm) contains the following subgroups:
– 0.10-0.18 µm (fraction = 0.01053)
– 0.18-0.30 µm (fraction = 0.08421)
– 0.30-0.60 µm (fraction = 0.25263)
– 0.60-1.00 µm (fraction = 0.65263)
• SS (sea-salt): Total 4, 1-Re=0.1-0.5, 2-Re=0.5-1.5, 3-Re=1.5-5, 4-Re=5-10 µm.
The data format of Gocart files is “direct access binary, 32 bits, big endian”. As an example,
here is how they should be read in Fortran 77 language:
dimension Q(imx,jmx,lmx)
do k=1,nstep
do n=1,nmx
read(unit) nt1,nt2,nn,Q
end do
enddo
where
• imx = total number of longitudinal grid (144),
†1
http://code916.gsfc.nasa.gov/People/Chin/gocartinfo.html