Incompatible with OPT flag unless
VRT flag also enabled
Either SFC or ZEN flags
must be enabled (but not both).
Notes
Solid angle integrations are defined as 2 π x u du where
u is the cosine of the zenith angle, integrated from 0:1, and
x is the quantity to be integrated. For transmittances and
absorptions, these are normalised by an factor 1/(2 π u du) =
1/π.
Integrations are performed using Gaussian 1st moment
quadrature (see Clough et al,
1992).
The number of coefficients
used is controlled by parameter NQAD
in subroutine rfmflx.for, currently set to 4 although values up to
5 are tabulated in gauqad.for.
NAD and
ZEN Flags:
when used in conjunction with the FLX flag these define
the hemisphere for integration as follows
RAD and COO Flags:
NAD/ZEN are optional and can be used to restrict calculations to the
upward/downward fluxes alone (rather than net fluxes).
TRA and ABS Flags:
NAD/ZEN are mandatory and define whether the transmittance is from the
output level to the surface/space respectively.
However, note that NAD/ZEN are not used with the MTX flag.
Sign: upward fluxes are defined as positive, downward as negative.
Cooling rates follow the sign of d(Net Flux)/dz, ie a net flux divergence
(increase in net flux with altitude) gives a positive cooling rate.
Units: using the FLX flag (without the
VRT flag)
also converts the
radiances from nW/cm2 to W/m2, i.e. multiplied by factor 1e-5
The VRT Flag allows the
solid angle integration
to be suppressed in which case this functions as a simple vertical ray path
calculation (and optical depth calculations are meaningful -
hence OPT flag may also be enabled).