Science Objectives:
Forecasts show low PSC probability in the region of Kiruna. The coldest temperatures are in the region of Frans Josef Land (FJL) and North Land. Back-trajectory RDF models suggest processed air in the rim of the vortex off the coast of Norway. The flight plan will be to takeoff in sunlight and fly across the predicted filament region in the sunlight to get measurements of ClO. We will then recross the filament as we approach Greenland. We will then turn back toward Spitsbergen and Frans Joseph Land and look for lee-wave PSCs would occur over these islands.
Flight Plan:
Takeoff from Kiruna at 10:00 AM local time. Expected flight duration: ~8:00 hours. A Russian observer was on board.
Report:
Takeoff at about 9:59 LT. ASUR did not detect any evidence of high chlorine at the vortex edge. The in situ instruments recorded in situ ozone of 100 ppt at FL 35. Broken clouds on the horizon prevented observation of the sun by the digital camera. DIAL ozone measurements were typical of vortex edge conditions.
AROTEL's temperatures show stratospheric values near 190 K, while MTP showed 200 K. This difference appears to typify many of the flights where we are seeing temperatures from AROTEL that are 5 to 10 K colder than the analysis, but usually in agreement with coincident sondes. I have noted that the forecasts tend to jump around as far as minimum temperatures at 480 K. I am hypothesizing that, when new radiosondes are injected into the assimilation, we get colder forecasts. Since the cold pool tends to be over Russia, maybe the assimilation of the data from these sondes is delayed as a result of the data coming in later than from other sondes.
Off the cost of Greenland (moving toward Ny Ålesund), we encountered a filament of high ozone and NOy air at aircraft altitude (37 Kft). As we entered the vortex off Greenland, sulfate aerosol began to swell at 20 km. DIAL showed ozone descending to lower altitudes. We could see the lights of Ny Ålesund. No lee-wave PSCs were detected over Spitsbergen.
DIAL and AROTEL observed a PSC over Frans Joseph Land at 20 km. Below the PSC, LASE observed thin clouds up to the tropopause. AROTEL temperatures showed 185 K at 22 km, 190 K at 20 km. Turbulence was noted at aircraft altitudes. Over Alexander Bell Island (flying east), the PSC became highly layered, with ~500 m separation in layers. The PSC extended from 18 to 23 km, with a sharp upper ledge. Wind speed 7 knots, wind direction from 227°. Mostly large particles - likely type II. We were unable to gauge the horizontal extent of the PSC in the downwind direction because the flight plan called for a turn to the north. As we went north, the PSC thinned to about 1 km thickness (from about 5 km), we turned back south and crossed under the PSC. It thickened over the island and then disappeared slowly south of Frans Josef Land.
As we moved south from Frans Joseph Land back toward Sweden, the ozone layer began to rise in altitude. We descended to 35 Kft for about 40 minutes and then to 41 Kft. Anomalies in water vapor, ozone and aerosols (filaments) were seen at this altitude. Larger anomalies were seen at 41 Kft- up to 0.5 ppm of ozone. These anomalies were highly correlated with NOy and anti- correlated with CO. DIAL indicated that the vortex was near northern Norway.