-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.