Tropical tape recorder observed in HCN

H. C. Pumphrey, C. Boone, K. A. Walker, P. Bernath, N. J. Livesey

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The tropical tape recorder is an effect in which a seasonal cycle in the mixing ratio of a gas is imposed on air entering the stratosphere and is then transported upwards by the Brewer-Dobson circulation. We report the observation of this effect in the mixing ratio of HCN, as measured by two satellite instruments: MLS on Aura and ACE-FTS on SCISAT-1. The cycle does not repeat every year; the data so far suggest that the dominant period is about two years. The reason for this periodicity is not yet fully understood. Comparisons with MODIS fire-count data suggest that it may be connected to inter-annual variations in biomass burning in Indonesia and the surrounding region.

Original languageEnglish
Article numberL05801
Pages (from-to)-
Number of pages6
JournalGeophysical Research Letters
Issue number5
Publication statusPublished - 1 Mar 2008


  • MLS

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