Science Objectives:
Forecasts show low PSC probability in the region of Kiruna. The coldest temperatures are in the region of Frans Josef Land (FJL), which is Russian territory. The flight plan is to head toward FJL to see if PS's are present. We will then turn toward Ny Ålesund and overfly the NDSC site. We will continue south toward Iceland where northward intrusion of midlatitude air is occurring. This will give us an opportunity to look at chemical processes on upper tropospheric/lower stratospheric cirrus. We will then follow the jet eastward, finally turning north toward Kiruna. We should be underflying the remnant of processed air from the PSC event of 30 November 1999.
Flight Plan:
Takeoff from Kiruna at 9:00 AM local time. Expected flight duration: ~8:00 hours. This will be the first official flight into Russian airspace. A Russian observer is on board.
Report:
Takeoff at about 8:52 LT. North of 74°, DIAL detected an increased aerosol backscatter in a layer about 4 km thick centered near 14 km. We entered Russian airspace at 10:24 LT. The in situ instruments recorded decreased ozone, NOy, and enhanced water and fine particles within the stratosphere north of Norway. Forecasts indicated that midlatitude tropospheric air may have moved into this region recently. The in situ measurements appeared consistent with the forecast. PSCs were observed at 11:30 LT just short of Spitsbergen (80°N); the layer was observed between 20 and 22 km. The layer increased in thickness along the flight track; ~20% depolarization was observed. Temperatures appeared to be 185K to188K or warmer from AROTEL. The particles were small. The PSC field disappeared on the other side of Spitsbergen (see map above).
As we approached Iceland, we observed a tropospheric fold with elevated in situ ozone, NOy, and higher stratospheric ozone above the aircraft. Below the aircraft, LASE recorded a classic fold structure with dry stratospheric air penetrating to 4 km. A smaller second fold was seen closer to the jet.
Near Keflavick, Iceland, ASUR reported seeing enhanced ClO. We also saw spikey (up to 30%) enhancements of NO and NOy which may have been due to aircraft exhaust. The cirrus decks which were predicted to show up near Iceland were present below the aircraft. At FL 390, we were above the tropopause on the leg east from Iceland, with thin cirrus decks just below us.
After we turned north to Kiruna, we descended to FL 370. We could see our contrail on the turn. FL 370 was just below the thermal tropopause. In situ ozone dipped below 100ppb, The temperature data showed we were just below the tropopause. We skimmed the tropopause for about 15 to 20 minutes. Cirrus was observed at flight level. We also saw NOy spikes (more aircraft exhaust). Once we crossed the jet, we saw another clear fold in the tropopause in both DIAL and LASE. ASUR showed ~0.5 ppb of ClO in the sunlit portions of this flight leg. Aurora were observed just before landing.