Michael Biggerstaff, Aircraft Mission Coordinator (TRMM OPS)
Peter Hobbs, Convair Chief Scientist
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Aircraft Mission Coordinator Summary
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All times below are UTC
Single aircraft mission: Convair
Convair t/o ~0123, land ~0520
TRMM OVERPASS: 0315 TMI only, SW quadrant
We should name this one "life at the equator". Despite being about 8.72 degrees from the equator, the ITCZ cloud band had ebbed to our latitude. Strong convection was located way east of the area during the morning forecasting brief. Satellite imagery suggested that our longitude was under the influence of a weak ridge and, despite our hopes, the weather would not be cooperative. The day was declared a no-fly day. P. Hobbs changed the Convair status to fly with a 0130 take-off after shower activity ignited just east of Kwajalein. There were several broad regions of precipitation with both intense convection and heavy stratiform rain within quantitative radar coverage. Indeed, echoes were moving to the northwest in the southern portion of the radar display and to the southwest in the northern portion of the radar display. It appeared as though the ITCZ convergence was aimed directly at the island.
Immediately after take-off the Convair was directed northeast toward a moderately strong region of convection with tops up to 9 km and peak reflectivity near 40 dBZ. The convection was propagating rapidly to the southwest while individual echoes drifted slowly westard. Several passes were made through this convective band with altitude ranging from 14K ft to 18K ft. At approximately 0213 the Convair transponder died and we no longer had track information for the aircraft. Despite the loss of position information, the aircraft reamined on duty penetrating moderately strong convection and sampling a growing region of stratiform precipitation.
At around 0300, the aircraft was moved to a smaller precipitation feature that was within the TRMM TMI overpass swath. This feature consisted of dissipating cells with tops less than 6 km during the initial pass. The Convair flew in the melting zone during the satellite sample period and made several additional passes through the weakening rainfall. Altitude ranges went from ~13K ft to 20K ft.
After obtaining data within the TMI overpass swath, the Convair was redirected back into a growing region of moderately strong convection. Just as the aircraft reached the area the entire zone ignited. Deep convective cells to 40K ft and higher with reflectivity > 40 dBZ covered an area that was about 15 nm in diameter. A particularly strong cell was just passing the center point of the line as the Convair made its initial pass near the freezing level. The aircraft diverted north after reporting strong updrafts. A new line on the northern end of the convective zone was established and the Convair made repeated passes down this line sampling mature and dissipating convection before sampling stratiform rain. A sloped descent from 13K to 8K ft was made on the final pass before returning to base.
In short, the Convair collected an excellent microphysical data base sampling strong through dissipating cells and heavy stratiform rain.
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Convair Chief Scientist Summary
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UNIVERSITY OF WASHINGTON FLIGHT FOR KWAJEX DATE: 30 Aug 1999 UW FLIGHT : 1799 Goals of Flight: Rainband study plus TRMM sat overpass at 1515 LT ("No fly day " for other aircraft) Accomplishments : One of best cases for Convair so far, as far as active convection is concerned. Measurements in two convective bands (one strong), and in a decaying band with TRMM sat overpass at 1515 LT. Period of flight: 1316-1722 Approx: Local Time (UTC=local time minus 12 hours) Activity LINE # 1 A= 08 deg 51 min/ 168 deg 22 min B= 08 deg 58 min/ 168 deg 35 min Good band 1343 1348 A to B at 15, 000 ft. Good cloud, but not bumpy. 1353-1358 B to A+ 6 nm at 16, 500 ft 1402-1411 A+ 6 nm to B+ 3 nm @ 18,000 ft. CPI working well (columns and plates) 1414-1423 B+3nm to A+ 6nm at 17, 000 ft 1426-1433 A+ 6nm to B+ 3nm at 13, 000 ft. Drops on CPI 1439-1442 B to A @11, 000 ft 1448-1452 A to near B @ 9, 000 ft LINE 2 A= 07 deg 48 min/ 168 deg 17 min B= 07 deg 44 mins/ 168 deg 02 min Weaker, decaying band. TRMM sat overpass at 1515 LT 1512-1518 A to B at 16, 300 ft (-0.5 deg C). Columns 1522-1528 B to A @ 17,000 ft (-1.9 deg) 1533-1540 A to B @ 19, 000 ft (-3.9 deg) 1548-? B to A @ 19, 700 ft (-6 deg) LINE 3 CANCELLED LINE 4 A = 08 deg 22 mins/ 168 deg 01 min B= 08 deg 21 mins/ 168 deg 23 mins Strong convective band 1623-1628 A to B @ 19, 200 ft 1630-1636 B to A @ 16, 000 ft (-0.2 deg) 1640-1646 A to B @ 13, 000 ft 1652-1658 B to A on slant path from 13, 000 ft to 8, 000 ft 2 1,000 ft / min. 1703-1704 Left and right banks for calibration of AMMR. Instrument malfunctions:
KWAJEX hours remaining: 35.97 KWAJEX (51.67)
2) (Aircraft transponder)
Univ. of Wash.