Summary of LEAR 36 FLIGHT #2 Monday 13/1/97 from St. John's, Newfoundland (YYT: 47.5N, 53W) all locations, altitudes, winds & temperatures are from controls & GPS in airplane cockpit (i.e. pressure altimeter), not from dropsondes. all information is approximate. takeoff: 9:41 Z from YYT (scheduled for 9:15 Z, fuelling delay). 6:11 local time. landing: 15:15 Z at YYT flight time: 5 h 35 min total distance: approx. 2000 miles during flight: no noteworthy weather, 30-100% cloud cover below flight level.. pilot: Gordon Stevenson (Flight International) co-pilot & navigator: George Kickhofel ( " ) dropsonde operator & chief purser: Dean Lauritsen (NCAR) science-liason-on-board & chief crew: Rebecca Morss (MIT) planned flight path: YYT -> 40N 58W, time of arrival = 11Z -> 40N 45W -> 48N 41W -> YYT drop ~ 12 sondes, at corners & midpoints of legs DROPSONDES: it takes an avg. of 30 seconds after launch for sonde to begin tracking satellites & obtain wind data (using GPS). several sondes took much longer to obtain winds, which is noted; thermodynamic data was still recorded in these cases. leg 1: increasingly slow air speed due to increasing headwinds. 1. 10:06 Z 45.8N, 54.0W 27000 ft = 8.2 km = 344 mb T=-47C winds from 196deg at 46 knots = 23 m/s near launch location 2. 10:39 Z 43.1N, 56.0W 27000 ft -45C 211deg at 79 knots = 40 m/s no sonde wind data above 7 km. beautiful sunrise! 3. 11:00 Z 41.5N, 57.0W 27000 ft -41C 233deg at 82 knots = 41 m/s proceeded into the 1st turn and were cleared to climb to 41000 ft by air traffic control. next drop was a few minutes after turn, in mid-climb. leg 2: tailwinds, air speed much faster. slow climb to 41000 ft due to air temperature. 4. 11:29 Z 40.0N, 56.6W 34500 ft = 10.5 km = 240 mb -43C 257deg at 137 knots = 69 m/s no sonde wind data above ~5 km. next sonde launched early to obtain wind data. 5. 11:35 Z 40.0N, 55.3W 37000 ft = 11.3 km = 217 mb -36C 259deg at 137 knots = 69 m/s no sonde wind data above ~9.5 km. 6. 11:44 Z 40.1N, 53.7W 39000 ft = 11.8 km = 197 mb -43C 271deg at 113 knots = 57 m/s no sonde wind data, probably due to error in detector channel (4). this channel was used for sonde 6 only. next sonde launched early to obtain wind data. noted 9C surface temperature. 7. 11:54 Z 40.1N, 51.8W 39500 ft = 12 km = 192 mb -41C 293deg at 144 knots = 72 m/s poor signal (but data still obtained) for 1st half of drop. noted 10C surface temp. 8. 12:12 Z 40.0N, 48.2W 40000 ft = 12.2 km = 188 mb -42C 272deg at 134 knots = 67 m/s 9. 12:28 Z 40.0N, 45.1W 41000 ft = 12.5 km = 179 mb -46C 280deg at 131 knots = 66 m/s altitude calcuated by sonde is ~ 5 km too low, due to bit error in signal. signal somewhat reduced at beginning due to turn just after drop. cleared back down to 27000 ft by air traffic control, began descent. drops 9-10 were slightly early in order to obtain higher altitude data. leg 3: 10. 12:43 Z 41.3N, 44.2W 35000 ft = 10.7 km = 239 mb -46C 253deg at 146 knots = 73 m/s 11. 13:18 Z 45.2N, 42.4W 27000 ft -43C 165deg at 51 knots = 26 m/s leg 4: 12. 13:44 Z 48.0N, 41.2W 27000 ft -43C 244deg at 120 knots = 60 m/s sonde launched just after turn. 13. 14:03 Z 48.0N, 43.8W 27000 ft -46C 214deg at 50 knots = 25 m/s 14. 14:34 Z 47.9N, 48.4W 27000 ft -49C 212deg at 22 knots = 11 m/s then back to St. John's. sunny & beautiful, very smooth landing.