Author of report: Mike Douglas

Mission Number: 030207I

Type of Mission: Low-level jet

Start time of Mission(UTC): 2003/02/07 11:56

End time of Mission(UTC): 2003/02/07 19:50

This mission was designed to describe a "classical (in terms of geographical distribution of wind speeds) low-level jet forecast to be present over southern Brazil and western Paraguay. The flight duration was kept short to allow for a possible longer flight the next day. The pattern was very similar to the previous day, with some short horizontal legs at 5Kft near Santa Cruz at the beginning and end of the flight. A leg towards the mountains west of Santa Cruz just after takeoff showed almost no decrease in the 5K ft winds until within several km of the mountains. However, a strong decrease in the winds was observed (and the end of the flight) to the south of Santa Cruz. During the main portion of the flight the porpoises revealed a strong jet, with maximum winds near 60 kt. The cyclonic shear side of the jet was well away from the mountains, and southerly winds were found near Villamontes, on the SW part of the track. Conditions were more cloud-free than on the previous day's flight. On the return transect of the jet the aircraft porpoised through the level of maximum winds to obtain higher spatial resolution of the jet core, roughly between the 310 and 316 K potential temperature levels.