What New Observational Information Is There About The Depletion Of Stratospheric Ozone?
Lowest Concentrations Of Ozone Measured By Satellite Over The South-Central U.S. During 1994 A combination of above normal temperatures and a persistent subtropical jet stream may be responsible for unusually low ozone concentrations over the south-central U.S. during November, 1994. The Total Ozone Mapping Spectrometer (TOMS) aboard the Meteor-3 satellite and the satellite-based TIROS Operational Vertical Sounder recorded the low ozone concentrations, as did ground-based instruments in North Carolina, Georgia, and Washington, D.C. Ground observations also confirmed that the low ozone persisted through December, although the concentrations were not as low as those in November. During the previous winter, ozone concentrations appeared to have returned to the winter values seen prior to the eruption of Mt. Pinatubo.
Reference: NOAA Climate Analysis Center, U.S. Monthly Climate Summary, Weekly Climate Bulletin, Vol. 94, p. 5, November, 1994.
1993 Ozone Measurements Over Antarctica Confirmed As The Lowest On Record Data from the Total Ozone Mapping Spectrometer (TOMS) instrument on the Nimbus 7 satellite showed that globally averaged concentrations of total ozone had decreased to unprecedented low values beginning in mid-1992 and continuing through early 1993. The ozone hole over Antarctica produced the lowest values of ozone ever recorded in 1993. During the same period, record levels of UV light were measured at the surface in Antarctica. At one monitoring site, UV-B, the part of the spectrum believed to be the most harmful to living organisms, was recorded at levels 44 percent higher than in 1992. 1994 ozone concentrations were also reported to be as low as the 1993 concentrations.
References: (1) Record Low Ozone at the South Pole in the Spring of 1993, D. J. Hofmann et al., Geophysical Research Letters, Vol. 21, pp. 421-424, 1994,; (2) Ozone Measurements, in Scientific Assessment of Ozone Depletion, World Meteorological Organization Global Ozone Research and Monitoring Project Report 37, Geneva, Switzerland, 1995,.
Longest Satellite-Based Stratospheric Ozone Profile Data Set Created The longest satellite-based ozone data set ever assembled has been created by combining observations from NASA's Solar Backscatter Ultraviolet Radiometer (SBUV) and NOAA's SBUV/2. The merged global data set covers the period 1978 to 1994 and is being used to evaluate global ozone trends. The data set of ozone vertical distribution obtained by the Solar Backscatter Ultraviolet (SBUV/2) instrument on the NOAA-11 operational meteorological satellite was reprocessed, leading to the currently available version (Version 6) data set.
Reference: Calibration of the NOAA 11 Solar Backscatter Ultra Violet (SBUV/2) Ozone Data Set from 1989 to 1993 Using Inflight Calibration Data and SSBUV, Hilsenrath E. et al., Journal of Geophysical Research, Vol. 100, pp. 1351-1366, 1995.
Lidar, Ballons, And Satellite Measurments Show Response Of Tropical Ozone To MT. Pinatubo Eruption Data on tropical ozone amounts taken before and after the Mt. Pinatubo eruption (June, 1991) show that there were significant decreases in lower stratospheric ozone in the year following the eruption. By comparing ozone measurements taken from airborne lidar and balloon ozonesondes during September 1991 and May-August, 1992 with sonde and satellite data taken previously, these changes were quantified. In September, 1991, the reduction in the 16-28 km region was some 33% (29±9 Dobson Units, DU) from pre-Pinatubo amounts. Comparable changes (33±7 DU) were observed in the summer of 1992.
Reference: Aerosol-Associated Changes in Tropical Stratospheric Ozone Following the Eruption of Mount Pinatubo, Grant, W. B. et al., Journal of Geophysical Research, Vol. 99, pp. 8197-8211, 1994.