40km Ozone Recovery

Newchurch M. J., E.-S. Yang, D. M. Cunnold, G. C. Reinsel, J. M. Zawodny, J. M. Russell III, Evidence for slowdown in stratospheric ozone loss: First stage of ozone recovery, J. Geophys. Res., 108 (D16), 4507, doi:10.1029/2003JD003471, 2003. Full Text

Global ozone trends collected by SAGE I/II along with HALOE provide evidence of a slowdown in stratospheric ozone loss since 1997.  Changes in the loss of HCl and several other ozone precursors in the upper stratosphere are indicative of the first stages of ozone recovery in the upper stratosphere and the ozone layer.

Figure 5. Coupling of CH4, H2O, and T with ozone at 35–45 km, 60°S–60°N. First panel: HALOE monthly averages for CH4, H2O, T, and HCl residuals plus trend in percent. The seasonal, solar, and QBO effects are subtracted from the original CH4, H2O, T, and HCl observations, respectively. Note that the vertical scale for T is 10 times larger. Second panel: combined CH4 and H2O impacts on ozone (blue line), which are empirically estimated from the regression analysis. For comparison, ozone trend plus residuals are shown with a black line. Third panel: estimated influence of T on ozone (red line) and ozone change corresponding to HCl variations (green line). HCl is selected as a proxy for stratospheric CFC. Fourth panel: observed ozone residuals plus trend (black line) compared to estimated ozone residuals plus trend by CH4/H2O/T/HCl impacts on ozone (blue line).

The above figure provides visual evidence of the effects of the Montreal Protocol at decreasing the amount of several ozone precursors in the upper stratosphere.  With these ozone precursors on the decline, the first stage of ozone recovery in the upper stratosphere.