G4 Flight in Support of IOP 9 (prepared by Bob Gall). Date February 1, 1997 Takeoff time: 9:02 Z Landing Time: (approx) 3:30 Z Goose Bay, Labrador Flight Duration: 6 hr 30 min (approx) The plane refueled in Goose Bay, left approximately 2 hr after it landed and proceeded to St Johns, Newfoundland. The flight to Newfoundland took approximately 1 hr 30 min and we landed at St Johns at about 8 Z. During the Goose Bay to St Johns leg in-flight data that included takeoff and landing soundings, were taken. There were no dropsondes. The primary purpose of this leg was to position the G4 in St Johns for missions either the next day, Feb 2, or the day after, Feb 3. In fact the return mission to Shannon was on Feb 3. Purpose The primary goal of this mission was to sample singular vector targets provided by NRL, in two areas. The first area was south of Iceland for a low that was forecast to be very deep and on the northern Norway coast in 48 hours. The second set of targets were south of Greenland and to the north of Newfoundland for systems expected in the MSA in 36 hours. Since we were to be in the vicinity of Greenland we used the opportunity to fly over the Greenland icecap and search again for the mountain wave. However the synoptic situation was different than it was for the previous flight to observe the Greenland mountain wave however. The low this time was much further east and there had not been a recent surge of warm air along the Greenland east coast. It was not known at the time of takeoff whether we would see a wave or not. The surface map consisted of a rapidly deepening surface low south of Iceland moving toward the northeast. There was a cold frontal system extending southward out of the low along the west edge of the MSA. A strong low was also present just south of Newfoundland that during the flight moved to a position just north of Newfoundland. This latter low meant that the weather at the time of landing in St Johns questionable and was the reason for the refueling stop in Goose Bay. Description of the Flight. The flight track was first north-northwest toward a point 61 N 17 W. The first sonde drop occurred at 10:36 at point 61 N 17 W and drop level was from 26000 ft. Shortly afterward we climbed and all sondes from that point until after we crossed the west coast of Greenland heading south were from above 41,000. At this time we were flying along a continuous cirrus shield to our left or toward the west of the flight track. After drop 1 we made the first turn, toward the left and toward 64 N 47 W in central Greenland. Drop frequency was about every degree of latitude until 34 W. From there until the turn point we were scheduled to drop at half degree latitude intervals. Our first drops indicated from their surface pressures that the surface low was deepening rapidly. Initial drops were to the east of the surface front. Drop 4 at 62.6 N 25.3 W was to the west of the front with a frontal layer extending up to 750 mb. The frontal inversion was very strong. At this time we were passing over continuous cirrus. A very sharp edge of the cirrus was passed at 11:32 Z at 63 N 29 W. From there to the Greenland coast the sea was first covered with stratocumulus then skies were clear as we approached the Greenland west coast. As we crossed the coast, skies were clear, views of the ground were good and little turbulence was encountered compared to the previous flight. Strong ground winds could be seen in the blowing snow on the ice though it did not appear as strong as on the previous flight. The ground was again covered with clouds as we approached the middle of the icecap. Because we apparently did not find a mountain wave on this leg of the flight, it was decided to reduce the drop frequency after 43 W to one a degree of latitude, then increase the frequency again after the turn point. The turn point at 64 N 47 W was reached at 12:36 Z. From there the direction was was first southwest to 59 N 50 W then directly south along 50 W. At 61 N we reduced our altitude to 26000 ft and stayed at that altitude until the end of the flight. The drop frequency was every half degree until about 60 N with one drop every one degree thereafter. This leg of the flight was generally within clouds until just before landing. On crossing the southwest coast of Greenland, no turbulence was encountered and we suspect that no mountain wave was present. The flight continued along 50 W to 52 N then west to 53 W where the last sonde was released. The sondes south of 55 N indicated southeasterly then easterly flow at the surface in connection with the low over Newfoundland. Flight level winds remained out of the southwest. Skies cleared just before landing in Goose Bay where the surface temperature was -26 C and winds were calm. Thick cirrus could be seen to the south and clouds were visible on the higher ground to the east of the Bay as we landed. The aircraft took a very good sounding as it came into Goose Bay. The flight to St Johns was first within clouds, then over middle clouds and these clouds extended to near the surface as we landed low in gusty surface winds at St Johns. Overall assessment of the Flight. The sondes to the east of Greenland produced a very impressive cross section through the front coming out of the low over Iceland. The front ended in a low stratosphere over the center of Greenland. The sondes south of Greenland will provide good coverage of the singular targets there. Sonde failure rate appeared to still be at about the 30% level though some can be recovered later. The Flight was considered to be a success.