Michael Biggerstaff, Aircraft Mission Coordinator (TRMM OPS)

Peter Hobbs, Convair 580 Chief Scientist

Michael Goodman, DC-8 Chief Scientist

Tony Grainger, Citation Chief Scientist

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Aircraft Mission Coordinator Summary
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Mission Summary for 28 August 1999 UTC, 28 August local

This is the second mission of the day.
All times below are UTC
Triple aircraft mission: DC-8, Citation, and Convair
Convair t/o ~0255, land ~???
DC-8 t/o ~0300, land ~0530 (not exact)
Citation t/o ~0305, land ~0526 (not exact)
TRMM OVERPASS: 0404 TMI mostly and PR in extreme SW quadrant (not sampled)

Convective activity earlier during the day had apparently suppressed the area around Kwajalein. By the time of take-off there were very few targets to fly. The aircraft were directed to a group of 3 weak convective cells with tops generally lower than 6 km. These cells were in the extreme northeast quadrant of the quantitative radar coverage. All three aircraft flew around (over or through) these small cells until they vanished.

The DC-8 reported that a line of more vigorous convection was organized NW/SE about 50 miles east of the region that was just worked. This was essentially the only precipitation within flight range of the aircraft. The low PRF radar scanned indicated some cellular activity on the west side of the DC-8 report but showed absolutely no echo beyond that region.

The DC-8 was directed to fly "visual" at 41K ft and sample the NW/SE oriented convective band. The two other aircraft were sent to the only viable radar target which was about 220 km from Kwajalein. At the time of the TRMM overpass, the DC-8 was returning along the NW/SE oriented band and the two other aircraft were making repeated passes through the small cells at the west end of the DC-8 run. None of the precipitation being sampled was within the TRMM overpass swath. Indeed, there was no echo anywhere within the TRMM overpass swath that could be detected by the Kwajalein radar.

The aircraft were directed back to base after the TRMM overpass. The Convair performed additional boundary layer runs before returning to base.

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DC-8 Chief Scientist Summary
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DC-8 Science Mission Summary

Flight: 990254=20
Date: 26 Aug 99 Julian Day 2238=20
Take Off: 0322618 UTC=20
Touch Down: 060554 UTC=20
Flight. Hrs. Remaining: 58.7 hrs=20

Mission Scientist(s): Michael Goodman and Anthony Guillory
Guest Scientist: Eric Smith
AMPR Scientist: Pete Conway
ARMAR Scientist: Bill Wilson
CPI Scientist: Paul Willis
CPP Scientist: Dan Wermers
SHIS Scientist: Dan LaPorte
Primary Objective: Fly over convection simultaneously with the TRMM overpass at 0452 UTC.=20

Secondary Objective: Scanning HIS infrared observations of cirrus coordinated with cloud physics probes of the cirrus particle size.

Flight takeoff originally planned for 0300 UTC was delayed until 0330 UTC due to lack of significant convection and problems with the AMPR data acquisition system.

The mission began with a flight to the SW quadrant of the 150 nm radar range ring to fly cirrus legs in support of S-HIS observations through cirrus. The DC-8 flew 4 dogbone legs through above, below and again through the cirrus. The first 7 minute leg was oriented approximately N to S through the cirrus beginning near 7:30 N, 167 E. The DC-8s second leg returned along a S-N leg above the cirrus and turned around for the third leg (N-S) below the cirrus. The final N-S leg (06:52 N, 167:09 E to 07:39N, 169:59E) ascended from 28000 ft to 38000 ft as the DC-8 passed from below to above the cirrus deck. The S-HIS team was very pleased with the observations. CPP observed intermittent large particles while in the cirrus. CPI fogged briefly during the descent from above the cirrus to below and could not observe particles at that time. After re-ascent CPI cleared up.=20

Although the AMPR data acquisition system failed shortly before takeoff, the AMPR engineering team was able to fix the data system and the AMPR started recording at 041935 UTC, just prior to the TRMM overflight time.

The DC-8 flew three passes along a N-S oriented bowtie pattern. The first leg from 08:18N, 166:21E to 08:40N, 166:21E began at 0443 UTC and ended approximately at 0456 UTC. ARMAR reported light to moderate rainfall during the TRMM overpass. AMPR's observations concurred with rainfall estimated at the 5mm/hr rate. The DC-8 turned around in a NW to SE bowtie leg from 044831 - 045055 UTC. Light rain was noted at the first half of this leg prior to the center point. The third leg flew N to S along the same line as leg 1 from 045403 to 045735. Both ARMAR and AMPR reported light/moderate rain at low levels.

The DC-8 was then vectored to a third location just off the northwest corner of the Kwajalein Atoll and performed a 5 leg series of N-S bowties over light convection from 0506 to about 0536 UTC. The Citation and Convair flew below at 20,000 ft and 12,000 ft, respectively. ARMAR and AMPR observed light rain as the storms were diminishing rapidly. With the storms dying the DC-8 returned to base landing at approximately 0606 UTC.

Michael Goodman,DC-8 Mission Scientist

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Citation Chief Scientist Summary
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Mission Summary For the Citation Flight of 8/28/99:

The Citation took off at 0305 UTC for a planned coordinated mission with the other two project aircraft to coincide with a satellite overpass. After looking for some time in the area for cells that might reach 20,000 ft, the Citation was directed toward a cloud outside the project area to the East, near where the DC8 had been flying. This relatively small cell had tops that reached 25,000 ft. The Citation made passes of this cell in 1000 ft increments, stepping up from 20,000 ft through 25,000 ft. The aircraft then moved to a different cell to the northwest of the first and made passes in 1000 ft increments stepping down from 24,000 ft through 20,000 ft. During this stepped descent, the cloud top was decreasing so that the aircraft was always very close to cloud top. There was no liquid present in any of the penetrations through either of the two systems. There being nothing else in the way of significant convection in the area, the Citation returned to base, landing at 0513 for a total mission duration of 2.1 hours.

Data Quality:

Most of the systems worked well throughout the flight with the exception of the FSSP and the King liquid water probe. The CPI was sometimes out of commission and it was shut down several times during the mission.

Flight Scientist: Grainger