Mission Summary for 16 August, 1999

Ed Zipser, Aircraft Coordinator (TRMM OPS)

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 Aircraft Coordinator Summary

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Mission Summary for 16-17 Aug UTC, 17 Aug LT.

All times below are in UTC

2-aircraft mission for Citation and DC-8.

DC-8 t/o ~2211, land ~0005 (not exact)

Citation t/o ~2227, land ~0040 (not exact)

TRMM overpass (TMI) at 2332.

The DC-8 and Citation were scheduled mainly on the strength of the good overpass for the TMI, hoping that some useful targets would be present. But the radar scope was so empty as takeoff time neared that we planned for some alternate, fair weather objectives instead.

The DC-8 mission was to fly a number of straight/level legs over the Ronald H Brown near the time of their 2300 UTC sounding. This was mainly for the scanning-HIS. While there were some layer clouds over Kwajalein, the sky was mostly clear at the ship's location, so this mission was done between ~2235-2310 and was apparently successful. As the overpass time approached, the DC-8 was sent NE toward the only weak radar echoes within range, but they were too small, and the DC-8 returned to base early.

The Citation mission was intercomparison with the low level data on the Brown and on Meck Island. First, the runs off the starboard side of the ship were accomplished between ~2237-2248. The a/c went from the Brown to Meck at about 500-600 feet, then did several runs between ~2300-2310 at 500 ft just east of the Meck tethersonde, which was held at 500 ft for the duration of the runs. The tethersonde was then released to complete their sounding. The Citation was then also dispatched to the NE area, found very small clouds at overpass, but nevertheless took cloud microphysics data on the pitiful clouds that were in the area until they reached their landing weight.

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DC-8 Chief Scientist Summary

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DC-8 Mission Scientist Report for 16/17 August 1999 (Julian Day 228/229) UTC.

The DC-8 took off at 22:12 UTC from Kwajalein in an effort to do a temperature and moisture intercomparison using the S-HIS interferometer with rawindsondes launched from the ship the Ron Brown anchored south of Kwajalein at approx. 08 22N and 167 44E. The DC-8 performed 5 passes over the Ron Brown at 22:25:49, 22:32:58, 22:47:01, and 22:54:12 (I may have missed a time!) in virtually clear skies (only widely scattered cumulus and cirrus) in the area. As well as over passes on both ascent and descent. The data over the Brown can also serve as a calibration dataset for both AMPR and ARMAR.

After completion of the flight legs over the Brown and prior to the TRMM overpass at 2334 UTC the aircraft was directed towards weak cells to the NE of Kwajalein, which for the most part had disspated before the aircraft reached it. Only a weak ice signature was identifiable in the AMPR data and ARMAR reported no precipition.

All instruments worked well. Although no microphysical data were taken since the aircraft was not in clouds during the flight. The AMPR data system crashed briefly at 22:35 UTC. Also, prior to the flight it was discovered that hydraulic fluid from the landing gear is apparently being sprayed into AMPR at times. This is resulting in the coating of the instrument with the fluid and the fluid is dissolving insulation surrounding the hot and cold calibration loads for the instrument. This situation will be studied to assess what - if any - action needs to be taken to make any needed repairs to the insulation and instrument after each flight. Prior to this flight the fluid was wiped off and post-flight inspection revealed no additional fluid on the instrument.

The DC-8 landed at 00:10 approx. using 2.0 flight hours leaving 82.5 hours for research use.

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Citation Chief Scientist Summary

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Mission Summary for Citation Flight of 8/16/99-8/17/99

The Citation took off at 2226 UTC for a planned fly-by of the Ron Brown and the tethersonde at Meck. The Citation went first to the South and did 3 passes past the Ron Brown at 500 ft above the surface and then did the same thing past the tethersonde at Meck. The Aircraft was then directed to the NE for a possible cloud study. There was very little in the way of active convection there by the time the aircraft arrived at the specified location. Since the Citation had to burn off fuel before landing, we stayed at that site making several passes through the cloud and spiraling up from about 14,000 ft through 18,000 ft and then spiraling back down to about 12,000 ft. There were nothing but ice crystals in the portions of the cloud colder than 0 deg C and light rain below the melting level. At the end of this maneuver, the Citation returned to base, landing at 0040 for a total mission length of 2.2 hours.

Data Quality:

The FSSP data is still suspect and the real-time winds are not good. All other instruments appeared to be working well. There was a brief power outage between the low-level passes and the arrival at the site of convection, The data system had to be rebooted, but nothing significant was lost during the time the data was not being recorded.

Flight Scientist: Grainger