The figure shows a sequence of near-global maps of N2O mixing ratio on the 1100 K isentropic surface (near 38 km altitude) derived from UARS CLAES measurements during 6-10 September 1992. Superimposed on the background structure of high values in the tropics is a 'tongue' of high-N2O air extending from the tropics deep into the southern midlatitudes. The time sequence clearly shows irreversible mixing from the tropics into midlatitudes. This is the first observation of such transport using UARS data.
Bill Randel Atmospheric Chemistry Division National Center for Atmospheric Research