Hurricane Luis
Extended Cyclone Dynamics Experiment (XCDX)
(950907I Aircraft 43RF -- single aircraft)
| Scientific crew |
| Chief Scientist | J. Gamache |
| Doppler Scientist | P. Dodge
W-C Lee (NCAR) |
| Dropwindsonde Scientist | F. Marks |
This document is divided into 3 sections (Each section is written by the Chief Scientist):
Mission Briefing
At the time for the mission briefing Hurricane Luis was moving toward the NW, north of Puerto Rico. The mission chosen was the Extended Cyclone Dynamics Experiment that called for a very large "4" pattern to be executed, centered on the storm center. Th
e desired location for the aircraft is just under the level where the melting band will be in stratiform areas. That flight level was chosen to be 14,000 ft. The radial legs were to be 200 nm out in the north, east, south and west directions from the ce
nter. The IP was to be 200 nm east of the center, then the aircraft was to proceed through the center and on to a point 200 nm west of the center. The downwind leg was to be from the west side to the south side of the storm, and the final leg was to be
from 200 nm south of the center to 200 nm north of the center. The aircraft was then to ferry back to Miami and Tampa.
Mission Synopsis
Take off from Barbados was at 1402 UTC. N43RF then proceeded northwest for nearly two hours. At 1548 UTC (21.07N 62.77W), the aircraft began to descend from its ferry level to its mission flight level of 14,000 ft. At 1606 UTC (22.47N 63.40W) it turned
inbound and tracked west to its IP which was reached at 1608 UTC (22.52N 63.52W). At the IP the first omega dropwindsonde was launched. The sonde performance was reported as very good. During the travel inward to the center an apparent 15 nm northward
deviation for weather was done, and thus at 1621 UTC the aircraft was at 22.77N 64.60 W. Shortly thereafter, however, it became apparent that this deviation actually lined the mission up with actual latitudinal position of the storm center. An outer e
yewall penetration was made at 1645 UTC (22.78N 66.49W) and a maximum wind speed around 103 kts was recorded. The wind speed then dipped, rising again to an inner maximum of 88 kts. The center was marked at 1652 UTC, 5 nm south of our closest point of
approach (CPA), at 22.77N 67.10W. From the CPA, N43RF continued westward, finding a peak wind speed of about 100 kts on the west side, in the outer eyewall. The westernmost point was reached at 1736 UTC at a position of 22.93N 70.65W, and the aircraft t
urned SE, tracking 135. An ODW was dropped at 173721 (22.82N 70.63W) that sent back good wind and thermodynamic information.
N43RF began the nearly hour-long downwind flight leg from the west to the south points, reaching the southern point in the pattern at 1830 UTC (19.72N 67.23W). After the aircraft turned northward, a third ODW was launched, and it was yet another good dro
p. The maximum winds on the south side, again in the outer eyewall were 115 kts, while the inner maximum was 78 kts. During this second pass through the eye, the center was marked at 23.20 67.40W at 1916 UTC. The ODW dropped in the center had good wind
s and thermodynamics, and found a splash pressure of 933 mb. The radar presentation showed the eye to be about 20 nm in diameter, with apparently 16-17 km radar echo tops on the north side of the center. As the aircraft proceeded north it found a 90 kt
inner eyewall maximum, and at 1925 UTC found an outer eyewall wind maximum of 115 kts. It appeared that the outer eyewall diameter had contracted from 45 nm to 35 nm between the first and second passes through the storm (an interval of 3 hours). N43RF c
ontinued to find 80 kts of wind or more out to a radius of 100 nm. At 2002 UTC (26.53N 67.43W), the aircraft turned toward Miami, ending the mission flight pattern. At 200433 (26.53N 67.63W), an ODW was dropped near 200 nm north of the storm center, and
then another was dropped at 205301 UTC (24.97N 72.00W) during the ferry home.
Landing occurred at 222658 UTC at Opa Locka, Airport in Dade Country, Florida.
Mission Evaluation and Problems
This mission was an excellent success. It was performed as planned, the ODW's worked very well, as did the lower fuselage and tail (Doppler) radars. The contraction of an outer eyewall from 45 nm to 35 nm was also observed.
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