DC-8 MISSION SCIENTIST REPORT (EJZ) 29 AUGUST 1998
Takeoff 190144 UTC/29 Aug Landing 025354 UTC/30 Aug
Mission objectives:
1. Execute a coordinated VME (Vortex Motion and Evolution) Experiment jointly between DC-8 and ER-2, and the two NOAA P-3's in Danielle. Result is 6 radial legs to 160 nm distance from storm, spaced 60 degrees apart, dropping sondes along each leg at 50, 75, 100, 130, and 160 nm for a total of 30 sondes. The NOAA P-3s (and the NOAA Gulfstream, in the more distant environment of the storm) also dropped sondes for a total of over 100. The P-3s obtained dual-Doppler data within a radius of 50 nm throughout the period.
2. Obtain the first of two days of data from LASE, MACAWS, and dropsondes in the clear inflow region on the south side of the storm. The idea is to repeat the pattern tomorrow, with more time available for an extended version, since we will not be doing the VME experiment.
Results:
All objectives were met, although with the one major disappointment that the ER-2 returned to base before reaching the storm due to an autopilot failure. About 33 dropsondes (from HRD) were used as part of the VME pattern, while about 6-7 (NASA's) were used in the ladder pattern on the south side for inflow. The VME pattern was interrupted after the first leg to do the inflow pattern, then we re-entered the storm on the east side to resume and complete the VME pattern. The storm structure was not well-organized at our level in either wind or rainbands or eyewall. one point, at 0013 UTC, the wind circulation at our level was displaced far to the southwest of the NOAA center. Max winds at our level were barely 40 knots, and not at any consistent radius from the center. The failure rate on the drops was about 20 percent for winds and zero (!) for thermodynamics. The storm structure was mapped by the combination of aircraft in a very complete fashion. The interruption in our pattern, about 2.5 hours, was approved in pre-mission coordination with the HRD scientists and was notthought to be a significant issue. Except for the failure the winds on two successive drops on the SW corner, all important objectives were met for the VME.
The points for the clear-air "ladder" pattern were moved about 50 miles west of their briefed position, based on a satellite image. Drops were made successfully. There was an unusually long delay in obtaining ATC clearance to change altitudes as we attempted to climb from 190-250 and from 250-350. Coordination with four ATC centers complicated the issue. Nevertheless the clear air inflow pattern was successful; LASE obtained very good data, and MACAWS especially liked the 19K' flight level.
