The analysis method used in this study is a three-dimensional variational scheme. Winds are matched as closely as possible to the observed Doppler radial velocities while satisfying the three-dimensional continuity equation. Filtering is also included within the cost functions used for the minimization. The wind grid and its filtering may be either cartesian or cylindrical (usually used for winds at the core of a hurricane).
The most extensive analyses of the Doppler data have been performed for the following dates: Hurricane Jimena on 23 September 1991, and Hurricane Olivia on 24 and 25 September 1994. The hodographs obtained from the mean wind fields for all penetrations on a given date are shown in Figure 1 for Jimena on 23 September and in Figure 2 for Olivia on 24 and 25 September. The shear on 23 September 1991 in Hurricane Jimena was east-southeasterly in the low-to-mid troposphere, while on 24 September 1994 the shear was weaker in Hurricane Olivia. The mean shear was no stronger on 25 September in Olivia than on 23 September in Jimena, however it was westerly. Hurricane Jimena remained at a virtually constant intensity for 24 hours, while during the flights of 24 and 25 September in Olivia, the hurricane strengthened 1-2 mb/hour on the 24th and weakened by as much as 3 mb/hour on the 25th. Possible contributors to the various evolutions on these three days must include not only the shear as manifested in the inner core, but also the sea surface temperature. On 25 September Olivia was traveling north across a sharp gradient of sea surface temperature, and this probably contributed to its decreasing intensity, and to its evolution from a very symmetric (Figure 3) to a highly asymmetric structure (Figure 4).
During FY1997, Doppler observations were placed in a composite relative to moving cells. For simplicity, the cells were considered to move at the speed of the tangential wind. The composite showed the circulation of the first cell examined to be organized in both the vertical (Figure 5) and horizontal directions. Further examinations will follow.