Summary of atmospheric chemistry observations from the Antarctic and Arctic aircraft campaigns

Summary of atmospheric chemistry observations from the Antarctic and Arctic aircraft campaignsAdrian TuckNOAA Aeronomy Laboratory, 325 Broadway, Boulder, Colorado 80303ABSTRACTIn the case 1,2 of the high altitude ER-2 observations of ClO, 03, H20, N20, NON, CFC13, CF2C12,condensation nuclei, wind, temperature and pressure are presented as averages of all flights. The data aredisplayed as vertical profiles over the airfields (Punta Arenas at 53°S, 71°W; Stavanger at 59°N, 6°E) andwithin the vortices at approximately 72°S and 78°N respectively. Horizontal profiles within isentropiclayers are also shown as averages. In the case of the DC-8, some examples illustrating importantobservations are given. The periods of the missions were 17 August -29 September 1987 and 3 January - 20 February 1989. 1 . VERTICALPROFILES : ANTARCTICAFig. 1 shows vertical profiles of variables listed in the abstract; in each case the contrast between theatmosphere inside and outside the vortex is manifest. The vortex interior is characterized by high ClO,decreasing 03, low H20, low N20, low NON, low CFC13 and low CF2C12 relative to its environs. Theinterior is cold, and the wind speeds increase with height.2. VERTICALPROFILES: ARCTICFig. 2 shows the Arctic data in the same format as figure 1. While ClO is high inside the vortex andN20 is low, 03 and H20 are higher (rather than lower as in Antarctica). Thus both vortices show elevatedClO from PSC-processing in air which has descended relative to the environs, but the vortex is notdehydrated as it was in the south, and the ozone had not been sufficiently depleted for the meridionalgradient to be poleward. The NO was depleted at latitudes 4°-5° poleward of the wind maximum aftermid January. Note that there is evidence for redistribution of NO, by gravitational sedimentation inside thevortex. Comparison between figures 1 and 2 reveals some asymmetries between the hemispheres, mostnotably in water vapor inside and outside the vortex. The dryness of the southern hemisphere is caused bythe ability of the colder southern vortex to dehydrate stratospheric air and convey the effects to mid-latitudes.3. HORIZONTAL PROHLES: ANTARCTICFig. 3 shows the same set of variables as in figs. 1 and 2, but plotted along isentropic flight legsbetween Punta Arenas and 72°S. Because the edge ofthe vortex can vary by up to 15° oflatitude onsynoptic time scales (a few days), the horizontal coordinate is degrees of latitude relative to the vortexedge. The averaging tends to smooth out the edge as seen in individual profiles, and it must be borne inmind that there was a clear time trend for ozone inside the vortex; synoptic scale variability tended toobscure other trends, but the water did appear to increase at latitudes inside and near the edge after themiddle of September.4. HORIZONTALPROFILES: ARCTICFig. 4 corresponds to Fig. 3, but for the Arctic. The averaging in this case obscures trends in ClO andNO in this case; the changing solar zenith angle affected the ClO abundance (more wifi be seen at lowerangles, as Cl202 photodissociates), as did the decreasing NO (by sedimentation ofparticulates) followingthe advent of frost point temperatures in mid January. By the first week of February, the interior of the