Variation of OH(6-2) and O2 airglow intensity (nocturnal means) at El Leoncito (32°S, 69°W). In these plots, the wave activity burst looks less dramatic (and the 2-day wave amplitude looks more uniform). But note that the scale includes zero, here. The intensities on January 8 are nearly as low as the lowest nocturnal means observed so far (the 1997 ENSO effect).

It is still unclear, whether the exceptional OH intensity on December 15 has anything to do with the two-day wave. The phenomenon is similar to the "most prominent" O2 airglow event on April 25, 1999 (Scheer and Reisin, 2002).

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