Stratospheric Ozone: Randel & Wu 2007

#The following was contributed by Bill Randel (NCAR), February, 2013:

The Randel and Wu (RW) stratospheric ozone data set was constructed by combining interannual ozone anomalies (derived from SAGE I+II satellite measurements and polar ozonesondes) with a background ozone climatology from Fortuin and Kelder (1998), to give a monthly global ozone data set covering 1979-2005. Description of the data and comparison of the interannual anomalies with independently measured column ozone variability is described in Randel and Wu (2007). The interannual anomalies are constructed using a multivariate regression fit to the gappy satellite measurements.  The data are intended to accurately capture seasonal and interannual variability associated with long-term decadal trends (including development of the Antarctic ozone hole), along with the 11-year solar cycle and stratospheric quasi-biennial oscillation (QBO).  

Strengths: Interannual changes are based on high quality, high vertical resolution satellite measurements from the SAGE I (covering 1979-1982) and SAGE II (1984-2005) satellites. These solar occultation measurements are the acknowledged ‘gold standard’ for quantifying stratospheric ozone changes during 1979-2005. Because SAGE measurements do not cover polar regions throughout the year, polar ozone is based on measurements from two high quality stations with near-continuous observations during 1979-2005 (Syowa at 69^o S, and Resolute at 75^o N).

Weaknesses: The data are focused on low-frequency interannual variability that is well-characterized by SAGE measurements (trends, solar cycle and QBO fits). The effects of the large volcanic eruptions of El Chichon (1982) and Pinatubo (1991) on stratospheric ozone are not included, as there were no observations during these periods (El Chichon occurred during the break between SAGE I and SAGE II, and SAGE II measurements after Pinatubo were unavailable due to excessive aerosol contamination). Also, month-to-month ‘natural’ variability of ozone is not included in these data.

Applications: The seamless global data are useful for forcing model simulations and characterizing low frequency variability in free-running models.

Common mistakes for users: unknown

Spurious features:  none

Corrections applied: no

Conversions for comparisons to model output: no

Comparable data sets: The historical, stratospheric component of the ACC/SPARC ozone data set (Cionni et al, 2011) is based on a data set very similar (but not identical) to RW.

Uncertainty characterized: Not explicitly. Comparisons to the global column ozone measurements (shown in RW) suggest an overall reasonable depiction of large-scale ozone variability and trends during 1979-2005.

Summary: The RW data set was intended to provide a simple global compilation of ozone variability and trends during 1979-2005 for use in forcing or evaluating global models. It has been highly utilized in the community.##