Mission Summary for 10 August, 1999

Ed Zipser, Aircraft Coordinator (TRMM OPS)

Tony Grainger, UND Citation Chief Scientist

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10 Aug (UTC and local date). All times in UTC

Single Aircraft Mission for Citation.

Takeoff 0320, Landing 0538 (times not exact)

(TRMM Overpass just before t/o, at 0313)

In view of the forecast, when the previous aircraft mission ended in

early afternoon, we did not expect to find viable targets for another

flight. But when new convective systems kept developing throughout the

day, it became of interest to get the Citation in the air if their

radio was in fact in working order. [They had been grounded since

their 1 August flight with not enough working radios for safety.] All

concerned did a good job of reacting to the situation, but the Citation

was not able to get into the air just after overpass time.

The mission was successful in sampling a significant convective system

about 60-80 nm SW of Kwaj from about 0340-0500. Actually the system

had multiple centers. The Citation was directed to the eastern

(weaker) center for the first few passes. When the portion of the

system about 12 nm farther to the west had weakened 'sufficiently' as

viewed on radar from the ops center, the a/c was moved there. In the

center of its first line through that system at 25Kft it took a

triggered lightning strike. Next line at 30Kft was, in deference,

moved slightly east of the strongest remaining echo. This system had a

total area of ~~50 X 100 km, with convective cores maturing

progressively farther west with time. The Citation made penetrations

at 15, 20, 25, 30, 25, 20, 15, and 18Kft before abandoning this system

due to new growth being out of quantitative radar range.

The last part of the mission penetrated some marginal cells near 08

55'/166 50' at 15 and 18 Kft before heading back to Kwaj.

UND Chief Scientist Summary

The Citation took off at 0320Z and flew to the SSW of Kwaj, where there was some significant convective activity. The Citation flew lines radioed from the operations center, starting near the melting level at 15,000 ft. and stepping up in 5000 ft. increments. During the line flown at 25,000 ft, the Citation was apparently struck by lightning. The Citation stepped up to 30,000 ft. and stepped back down to 15,000 ft. Around 0440, while flying a line at 15,000 ft., the Citation was beneath some mamatus and it climbed up to 18,000 ft. to make a pass through that feature. A number of smaller cells were penetrated and the Citation started back toward Kwaj at around 0520. The Citation landed at 0540.

Data Quality. Most of the data looked good in real-time, but there were several areas of concern. The King liquid water probe data did not look good and the reason was not clear. The 2D-C and HVSP was not updating in real time during several periods. It looked as though the data was going to tape, but the data needs to be processed before it can be determined if this was a significant problem. The CPI probe appeared to be working well. There were problems with the real-time display of the winds. However, it appeared that all the individual components going into the wind computations were being recorded, so the calculated winds should be good. It is believed that this problem is due to the INS not receiving the correct true air speed.

Flight Scientist: Grainger.