The relationships between two instruments for overlapped time periods are summarized in the contour plots. (Click on the figure below for the full size version.) The contour plots show the average differences between the zonal mean mixing ratios (ppmv) at pressures from 50 hPa to 0.5 hPa (21 km and 54 km) from two satellites during an overlap period. Percent difference greater than 10% in absolute value are included in the appropriate �(6 to 10)% classes.