Open Access

Unusually low airglow intensities in the Southern Hemisphere midlatitude mesopause region

Earth, Planets and Space201452:BF03351635

DOI: 10.1186/BF03351635

Received: 4 August 1998

Accepted: 15 February 2000

Published: 20 June 2014

Abstract

During the first part of a new set of airglow observations in the OH (6-2) and the O2 (0-1) Atmospheric bands from El Leoncito, Argentina, that started in August 1997, periods of surprisingly low intensities stand out. For many nights, mean O2 intensities reach only 30%, or less, of what we have seen in previous campaigns, from 1984 to 1994, at the same site, or a similar latitude. Such an anomaly is also observed, to a lesser degree, in OH intensities. An instrumental artifact in the intensity results can be ruled out by using the signal from the stellar background for a “field calibration”. A relation to the strong ENSO event with its major climate impact in 1997/8, may, of course, be suspected, although a statistical inference would be weakened by the scarceness of historical precedents of a similar magnitude.