Author of report: Mike Douglas

Mission Number: 030121I

Type of Mission: low-level jet

Start time of Mission(UTC): 2003/01/21 10:39

End time of Mission(UTC): 2003/01/21 19:17

Flight involved near maximum mission to describe low-level jet present over eastern Bolivia. Strong surface winds at Viru-Viru at takeoff time, aircraft passed through 48 kt peak winds at 860mb during ascent from airport. Flew initially at 836mb (5K ft) a leg west to base of mountains, then turned north while maintaining this altitude. Winds reached 59 kts before aircraft began porpoising / ferrying to point near 11S, 66W. Northern leg was slightly shortened, with flight following pattern similar to Flight #2. Porpoising generally between 300m AGL and 12000 ft pressure altitude, with some ascents to 14000 ft because of strong westerly winds found at higher levels (between 700 and 600 mb) over northern Bolivia. During a 5K ft segment approaching the mountains near 14S, 68W the winds maintained 50+ kt speeds even close to the mountains. In general, winds were stronger than expected. with winds near 850 mb being strongest very close to the mountains. Near 700 mb the winds were stronger (~25 m/s max) over northern Bolivia, with a region of strong cyclonic shear near 17S between 40 kt westerly flow and 10 kt westerly flow farther south. Relatively clear, but hazy skies prevailed during early part of the flight, becoming dominated by PBL clouds during later flight. No significant deep convection along track during flight.