-3-
_
.
(2),
One of the major codes that was modified is MATHEW I its purpose 1s to
adjust observed winds, using variational analysis methods, so as to conserve mass
from cell to cell. After modification, all observed uoper air wind data from 19 m to
35 Km were entered as input. This vas done for four time periods, using winds for
one to three observing stations for each time. The oovious advantages of this code
(over most other fallout codes) is that mass is not permitted to accumulate in anv of
the cells and winas are available for each 3-D cell intersection for four times.
Tne MATHEWwinds are used then by the modified appicl’l particle-in-cell
code to calculate the transport, diffusion, and deposition of an
source.
allowing
instantaneous
Modifications required of ADPIC, to handle the Bravo test, consisted of
more
upper
air
input
than
is
used
in
tvpieat
ARAC
assessments.
rurthermore, since particles falling from the stratosphere undergo a larga increase
in air density, it was necessary to add a turdulent wake correction to the larger
.
.
.
[-
particles; this correction follows the method set forth by \eDonald-*
modifications were to incorporate a
tropical atmosphere
into the
Other
fall velocity
calcuations and to make the particle activity increase as the cube of particle
radius. Finally, time-integrated deposition was added; this allows calculation of the
total dose from detonation time to evacuation.