DATA PRODUCTS: Tropospheric column ozone (TCO) and stratospheric column ozone (SCO) measured in Dobson units (DU). All TCO and SCO measurements were determined using TOMS Version 8 measurements of column ozone and reflectivity.

TEMPORAL RESOLUTION: Monthly averages from January 1979 to the present.

HORIZONTAL RESOLUTION: 5 degrees latitude by 5 degrees longitude.

LATITUDINAL COVERAGE: Central latitudes (in degrees) -12.5, -7.5, -2.5, 2.5, 7.5, 12.5.

LONGITUDINAL COVERAGE: Central longitudes (in degrees) -177.5, -167.5, ..., 177.5.

OVERVIEW OF CCD METHOD: Monthly averaged TCO and SCO data are derived in the tropics for January 1979-present using the convective cloud differential (CCD) method of Ziemke et al. (JGR, 1998). In the CCD method total column ozone is derived from low reflectivity (R<0.2) measurements and SCO follows from nearby column ozone measurements taken above the tops of tropopause level clouds under conditions of high reflectivity (R>0.9). Above-cloud column amounts (in 5 degree by 5 degree bins) are first evaluated in the Pacific region where tropopause/near-tropopause level clouds are common. SCO is then derived for every 5 degree latitude band for 120E eastward to 120W using only the lowest values of above-cloud column amounts (it is the average of these lowest column amounts over the Pacific that becomes our estimated SCO). These SCO values from the Pacific region are then assumed to represent SCO at all other longitudes in a given latitude band. This assumption is based on the zonal characteristics of tropical SCO as inferred from Stratospheric Aerosols and Gas Experiment (SAGE) ozone, and as inferred from Upper Atmosphere Research Satellite (UARS) microwave limb sounder (MLS) and halogen occultation experiment (HALOE) ozone.

MISSING DATA: All months from May 1993 through July 1996. Other months may have some missing data. Missing data are given a value of zero.

ESTIMATED MEASUREMENT UNCERTAINTIES (2-SIGMA VALUES) IN TCO DATA: 3 DU in the Pacific increasing uniformly to 6 DU over the Atlantic.

ESTIMATED MEASUREMENT UNCERTAINTIES (2-SIGMA VALUES) IN SCO DATA: 3 DU in the Pacific increasing uniformly to 6 DU over the Atlantic.