-3-
One of the major coces that was modified is warHew?), its ourpose is to
adjust ooserved winds, using variational anaivsis methocs, 50 as to conserve miss
trom cell to cell.
After modification, all observed voper air wind data from 19 mto
35 km were entered as input.
This was done for four time periods, using winds for
one to three observing stations for each time. The ovvious advantages of this code
(over most other fallout codes) is that mass is not permitted to accumulate in any of
the cells and winds are available for each 3-D cell intersection for four times.
Tne MATHEW winds are used then by the modified appicl?l particle-in-cell
eode to calculate the transport, diffusion,
source.
allowing
and
deposition
of an
instantaneous
Modifications required of ADPIC, to handle the Bravo test, consisted of
more
upper
air
input
than
is
used
in
typical
ARAC
assessments.
rurthermore, since particles falling from the stratosohere undergo a large increase
in air density, it was necessary to add a turdulent wake correction to the larger
.
.
.
(4
particles; this correction follows the method set forth by SeDonald-
Other
modifications were to incorporate a tropical atmosphere into the fall velocity
calcuations and to make the particle activity increase as the cube of particle
cadius. Finally, time-integrated deposition was added; this allows calculation of the
total dose from detonation time to evacuation.