The small percentage of total debris sccoumted for by the observing network ia somewhat puzzling. Although it must be assumed that a large fraction of the active debris was deposited in the vicinity of the test site, it is also true that the shortcomings of the guwamed film technique, which have been discussed in previous reports, may be responsible for the effect noted. A suggestion that increased "stratospheric storage” may be important is indicated by the fact that approximately 1% of the debris from the Castle series was detected, ss compared to over LS from the Ivy series.# : Since the three most powerful bursts of the Castle series were considerably larger than the Ivy Mike test, it is possible that a larger fraction of the debris was transported initially into the lower stratosphere. 3.4 METECROLOGICAL INTERPRETATION The total fallout from the Bravo test (Figures 3.3 and 3.h) clearly show the tendency for the major activity to ressin near the source latitade, In marked contrast with the fallout from the Ivy series, there seems to be no evidence that debris wes carried northward around the western side of the Pacific high-pressure cell. Almost no fallout occurred in Japan, and very little on Iwo Jima - from the Bravo test, while Ivy Mike resulted in more fallout on Iwo Jima than on any of the other Pacific Islands. The difference between the two tests is a result of the seasonal difference in the location and intensity of the western cell of the Pacific high. This cell is almost non-existent, in the mean, during the winter and *?The figures given in Table 6.2 of reference (2) have been revised following a recalibration of the counting equipment. The revised figures are: Ooserved World-wide Total (magacuries as of 1/1/53) Mike Ivy total - 33-