DC-8 MISSION SCIENTIST REPORT (EJZ) 23 AUGUST 1998

Takeoff 173444 UTC/23 Aug Landing 001308 UTC/24 Aug


Mission objectives:

1. Execute two "figure-four" patterns through the center of Hurricane Bonnie, coordinated between DC-8 and ER-2, and (more or less) with two NOAA WP-3D's as well. Result is 8 radial legs to about 100 nm distance from storm, spaced 45 · apart.

2. Perform three passes just offshore of the Andros Island site, followed by a final pass from E-W directly over the site.

Results:

Mission flown as planned. Storm had moved more slowly than anticipated, so after briefing had to adjust all coordinates about 6 minutes north and 48 minutes east. The storm structure was conplex and interesting. The wind eye at our altitude was displaced some 20 miles to the NW of where the WP-3Ds were reporting it, and where a crescent-shaped echo on the east side of the eye suggested a tight center might be located. The wind speed was stronger on the west side, but convection and turbulence (never more than light) was stronger onthe east side. On a few crossings on the E side, there was strong diffluence out of the convective bands, as much as 70-90·.

Ed Zipser

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DC-8 MISSION SCIENTIST REPORT (EJZ) 24 AUGUST 1998

Takeoff 193904 UTC/24 Aug Landing 032758 UTC/25 Aug


Mission objectives:

1. Execute two "figure-four" patterns through the center of Hurricane Bonnie, coordinated between DC-8 and ER-2, and (more or less) with two NOAA WP-3D's as well. Result is 8 radial legs to about 100 nm distance from storm, spaced 45 · apart. In addition, in an attempt to get data from LASE and MACAWS, the second figure-four has legs extended to 140 nm radius.

2. After the last pass through the storm, execute a long leg under the anvil on the west side of the storm to a position close to Andros Island, then fly a data leg just east of Andros site on the return to Patrick.

Results:

Mission flown as planned. All pre-briefed points had to be shifted to the ENE by about 30 nm due to updated storm center fixes. The ER-2 lost their nav
computer, so we had to be judicious in passing new way points to them, but thanks to the good work of our Navs and the ER-2 pilot the mission was saved.

Wind and cloud structure in Bonnie on this day was very interesting. While remnants of an inner eye were occasionally visible, including a report of a big buildup, the large radius eyewall was more prominent, at least at our altitude. As on the previous day, strongest winds tended to be in the quadrants away from the convection. There were west and northwest winds dominating the western semicircle right into the center, while a major divergent source region was on the east side. This source region apparently was responsible for the huge cirrus shield extending even to 140 nm west of the center, with falling "snow" at our altitude in spite of strong west (!) winds. On entry from the west, at about 2306 UTC, the large-scale eye was manifestly visible in a swirling pattern in the low clouds, but this feature was about 30 nm NW of the eye position as reported by NOAA and the wind eye at our altitude.

Ed Zipser

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DC-8 MISSION SCIENTIST REPORT (EJZ) 26 AUGUST 1998

Takeoff 110401 UTC/26 Aug Landing 182629 UTC/26 Aug


Mission objectives:

1) Obtain data from the ER-2 and DC-8 on clouds and precipitation over and within Bonnie as possible at/near the times of TRMM overpasses at 1135, 1313, and 1449 UTC.

2) As Bonnie approached landfall near Cape Fear NC, execute coordinated passes through the storm with the ER-2, DC-8, and NOAA 42, all within a radius of 100 nm.

3) Obtain LASE and MACAWS data in the clear-air inflow region southeast of Bonnie.

Results:

All objectives were met. The storm continued to exhibit a huge eye, with the eyewall almost closed, circular, and about 100 nm in diameter. THe north wall had heavier rainfall rates, but at no time was any turbulence more than light encountered at DC-8 level. Indeed, after the first figure-four was completed at 35K' we descended to 30K' for the second figure-four. The wind pattern was more symmetric than on the two previous flights, with mainly cyclonic flow at all radii out to >100 nm, and wind maxima quite far away from the center, in the 50-60 knnot range. The clear air inflow leg on the SE side was indeed mostly clear above the low broken clouds in the lowest 1000-1500 m. On exit, we modified the return leg to come through clear air southwest of the storm before returning to Patrick AFB.

Ed Zipser

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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.

Ed Zipser

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DC-8 MISSION SCIENTIST REPORT (EJZ) 30 AUGUST 1998

Takeoff 194921 UTC/30 Aug Landing 033617 UTC/31 Aug


Mission objectives:

1) Begin by documentation of storm structure in Danielle through execution of two figure-fours to 100 nm radius at 35000'. Coordinate closely with ER-2, more loosely with the NOAA P-3 (NOAA 43) doing the 100 nm radius pattern, and still more loosely with NOAA 42 operating along six radials of 300 nm each.

2) Major objective of mission follows the figure 4's: an 11-pointed sawtooth pattern crossing the (formerly!) clear "inflow" area from the northeast quadrant, through southeast, and around to the southwest side.

3) After completion of (1) and (2) above, the DC-8 leaves the pattern close to Andros Island, does a leg along and just east of Andros, coordinated with the ER-2.

Results:

All DC-8 objectives were satisfied. The early departure of the ER-2 and the need to turn off E-DOP was a disappointment, as there was no EDOP data over Danielle, and of course the ER-2 did not go to Andros.

Danielle gradually developed a better-organized inner core structure at DC-8 altitude. Even on the first pass (W-E), there was a circular radar eye (DC-8 radar) of about 40 nm diameter and some noticeable updrafts in the west wall cloud on entry. Throughout the two figure-four patterns, the best convection appeared on the west semicircle, sometimes with light-moderate turbulence. No lightning was observed in the eyewall, although some was later observed in the "clear slot" on the SE side at large radius from more isolated storms. The wind eye was fairly well-marked by 30-40 knot winds at radii of 25-30 nm.

The large sawtooth pattern encountered more clouds than had been anticipated; during the 8-9 hours that elapsed since mission planning the clear area on the east and south sides had filled in considerably. (This could have ben flown first, had not the Andros overpass been scheduled for after dark, which constrained the flight planning for the main mission.) Despite the cloud increase, most of the pattern obtained good data, especially at 19000' on the NE side, and at 21000' on the south side. The Andros overpass was made as scheduled, but I do not know whether the cloud conditions were considered suitable.

Ed Zipser

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CAMEX-3 Update: 9/21/98

Today,s Georges eyewall flight was a success. Georges showed many unique characteristics including large turrets, variable eyewall winds, and wind speeds up to 80 knots at FL 330. The eyewall pattern was also significantly displaced from the radar eyewall location unlike those seen with Bonnie, Danielle, or Earl.

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CAMEX-3 Update: 9/22/98

Today's Georges synoptic / water vapor inflow flight was a success. The hurricane had already made landfall over Hispaniola and impacting the mountains there. Rarely seen lightning fields and sprites were noticed in the eye of the hurricane from the ER-2 altitude. This was the DC-8's last CAMEX-3 flight (Thanks to the crew for your excellent support!) The ER-2 could extend and even possibly divert to Robbins if required. Tomorrow will be a no-fly / pack day.

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CAMEX-3 Update: 9/25/98

The ER-2 launched from Warner Robins, Georgia at 8:30 am (EDT) on September 25 to sample Hurricane Georges as it was moving through Key West and along the western coastline of Florida. Dee Porter, the ER-2 pilot, flew East/West legs through the hurricane eye as the storm headed north. He then headed to Melbourne, Florida to fly under the TRMM satellite and over the TRMM rain gage network and the S-POL radar.

The ER-2 pilot noticed the hurricane eye would appear and disappear between eye crossings. He also experienced considerable turbulence at 63,000 feet. He reported that the turbulence smoothed out once he increased his altitude to 65,000 feet. He described the clouds surrounding the eye as a "bubbling caldron." As comical sidelight, he also found that two pairs of Florida lovebugs accompanied him in the cockpit during the trip.

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CAMEX-3 Update: 9/27/98

The NASA ER-2 aircraft took off from Warner Robins Air Force Base today (September 28) at 10:30 am (EDT) to sample the rainbands of Hurricane Georges north of the eye. Jim Barrilleaux, the ER-2 pilot, flew a triangular pattern from approximately Fort Walton Beach, Florida due west to Slidell, Louisana. After this point, he headed southeast to 28 degrees North latitude and 88 degrees West longitude which was should have been an area south of the forecast position of the eye. After passing through this point the pilot headed back to Fort Walton Beach. This triangular pattern was flown twice before the pilot broke off to fly under the TRMM satellite at 2:14 pm (EDT). He then returned to the triangular pattern for one more pass around. The total flight time was 6.5 hours.

The pilot observed a solid cirrus shield during the triangular manuever. He did not see any cloud feature resembling an eye until he approached the TRMM subtrack. At that point, he noticed a feature to the south of his track with bubbling cloud formations. His aircraft altitude during most of the mission was 65,000 feet. He did not experience any turbulence.
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For information about NASA CAMEX-3 Robbie.Hood@msfc.nasa.gov

Updated Thursday, 15 October 1998made with Mac