LAB “L" ~ PROBABILITY OF OCCURRENCE OF UPPER WINDS WITH SOUTHERLY CO:PONENTS IN THS ENIVETOK-BIKINI AREA - c (Sxtract from detailed studies made on this subject by the Task Force Weather Central.) wt Winds with southerly components at Eniwotok are much less prevalent than winds with northerly components. Up..er wind data obtained by rewin= sonde equipment since 1945 have been compiled. The frequency of occur res oy winds with southerly components is shown in the attached graph Inc ° The upper portion of the graph shows that winds with southerlycom ponents (1.¢., east-southeast clockwise through west-southwest) have occurred about thirty-five per cent of the time during the months of March through July at levels of about 10,000 fect. The lower portion of the graph shows that southeast through southwest winds have oecurred about twenty per cent of the tine during the same months at the same levels. The differences are due to tha high frequency of east-southeast winds at about 10,000 and 16,000 feet and the high frequency of west-southwest winds above 25,000 faet. A slight trend for higher occurrence of winds with southorly com ponents is indicated as the season progresses. Extreme care must be taken in drawing conclusions from these data» for three reasons: 1. Tho sample is small. The 49,000-foot data consist of lass than 100 observations for March and April. 2. The variation of Marshall Islands weather for a given month dure ing successive years may be greater than the variation during successive months. Note the high frequency of southerly winds at 49,000 to 50,000 feet during March as compared to April, iay and June. The weather of March 1951 constituted most of this abnormality. 3. The data are tabulated for oach level without reforonce to adjacont levels. To evaluate the importance of the third factor, Item 3 above, 4 tine- wind graph of Eniwetok winds has been analyzed for the period 1 January through 14 May 1954 (Incl 2). The winds aloft at Eniwetok and Bikini were very similar during the ontire period except from 23 April through 5 May. The winds were more southerly at Bildini than at Eniwetok during that per- lod; and Bikini winds are shown for comparison purposes. From this graph, data were obtained as to the simultaneous occurrence of southerly winds at 50,000 feet and at levels below. The results are shown in Table I following: