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ELECTRONIC FILE CHARACTERISTICS: 3 files; MS Word (.DOC) and Adobe Acrobat (.PDF). PHYSICAL DESCRIPTION: 1 computer laser optical disc (CD-ROM); 4 3/4 in.; 2.91 MB. SYSTEMS DETAIL NOTE: IBM-clone PC-compatible. ABSTRACT: Satellite derived wind, rain rate and sea surface temperature data combined with NCEP analysis data are used to examine the structure of the South Pacific Convergence Zone (SPCZ) during La Nina conditions. Annual means indicate that the axes of maximum surface convergence and rain rates are essentially co-located in the Northern Hemisphere Inter-Tropical Convergence Zone and over the tropical (TR) portions of the SPCZ. However, over subtropical (ST) and middle latitudes (ML), the axis of maximum convergence is eastward and equatorward of the axis of maximum rain rates such that surface divergence predominates over the these portions of the SPCZ rain rate maximum. Analysis NCEP data also exhibit a similar convergence distribution at 1000 hPa; however, at the 925, 850 and 700 hPa levels convergence replaces divergence and is co-located with the axis of maximum rain rages. Seasonal rain rate patterns indicated that the TR and ST SPCZ are more convectively active during Austral Summer and Fall while the ML SPCZ is more active during the Fall land Winter. Vertical wind shear and the variability of the meridional flow indicate the ML SPCZ is strongly associated with the mid-latitude storm track while the TR SPCZ is associated with low wind shear. The ST SPCZ represents a transition zone between an environment dominated by low shear and one that is more baroclinic.

Knowledge of the strength and horizontal extent of damaging winds from the center of a tropical cyclone is crucial for coastline preparations, forecasting coastal flooding and shipping interests. This study attempts to improve our understanding, estimation and prediction of the outer wind profiles of typhoons. The mean radii of 30 knot (R30), 50 knot (R50) and 65 knot (R65) winds are calculated using aircraft reconnaissance, satellite and synoptic data for 35 tropical cyclones during approximately 300 different time periods. By examining the change in the outer wind profile with time and central pressure, three cyclone classes were noted. One class of cyclones experiences a R30 increase which persists at least one day past its maximum intensity; these are termed 'delayed.' Another class experiences a trend in R30 that follows the trend in the central pressure; these are termed as 'simultaneous'. Similar differences were noted for R50 and R65 in simultaneous and delayed cyclones. However, the differences in the two cyclone classes diminish as one goes closer to the inner core. A less common class of cyclone had R30 values that were very large from the beginning of their formation and remained large throughout most of its life cycle. These were designated 'gyre' cyclones. Changes in outer winds as related to time of year, cyclone direction of motion, cyclone size and intensity are discussed for these cyclone classes. Composites of each cyclone class were created and the life cycle of the outer winds, central pressure, eye size, and synoptic size were investigated.