Principal Investigator: Samuel J. Oltmans
Co-Investigator: Daniel Jaffe
Co-Investigator: Bryan Johnson
Institution: NOAA Climate Monitoring and Diagnostics Laboratory
Period of Performance: April 1, 1997 - October 30, 1997
December 4, 1996
Total Amount Requested: $58,250
The high latitude stratospheric ozone seasonal variation can be attributed to the in situ photochemical destruction of ozone resulting from long periods of solar illumination. The objective of the ER-2 aircraft campaign is to evaluate ozone loss rates associated with the major catalytic loss cycles (HOX, NOX, ClOX) and determine the effectiveness of each my measuring key species in the hydrogen, nitrogen, and chlorine reservoirs along with aerosols combined with appropriate photochemical modeling. Three aircraft campaigns are to be carried out over the April - October 1997 period that will cover a wide range of latitudes and altitudes up to 20 km. The work proposed here will provide a context of vertical ozone profiles at Fairbanks, Alaska, during the spring through autumn period. During the aircraft campaigns additional profiles will be obtained.
The lower stratosphere at high latitudes shows large variability in ozone concentration on a seasonal and also on shorter time scales. This is illustrated in recently obtained profiles (figure 1) which show the dramatic changes that can take place during the month of November. On the first 2 days (November 8 and 12, 1996) there is only a small difference in the tropopause (near 10 km), but the ozone amount between 10 and 20 km is remarkably different in the two with approximately 70% more ozone on November 8 (1.7 ppmv) than on November 12 (1.0 ppmv) at 17 km. By November 15 the tropopause is at 15 km, and the ozone mixing ratio in the 15-20 km has been reduced even further to about 0.6 ppmv at 17 km.
It is expected that in the spring similar variations will also occur. During November it is likely that the dramatic changes seen between the times of these profiles are related to changes in the circulation in the lower stratosphere with air coming from different regions on these 3 days. With the ozone vertical profile information from the ozonesondes, the progression of these changes through the seasons as well as within a month can be tracked along with their altitude structure. This data could be useful as well in planning aircraft flights by confirming the type of air mass that the ER-2 would be ascending through.