Journal of Geophysical Research: Atmospheres

Record of tropical interannual variability of temperature and water vapor from a combined AIRS-MLS data set

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Abstract

[1] We utilize a merged AIRS and MLS temperature and water vapor record (August 2004 to March 2010) to study the atmospheric variability of these quantities. The seasonal and spatial distribution of temperature and humidity shows the tropical western Pacific (TWP, 8°S–8°N, 120°E–170°E) to be a location with persistent deep convection and the tropical central Pacific (TCP, 8°S–8°N, 120°W–170°W) to be a region of subsidence, consistent with previous work. Furthermore, our estimates of 3.9 ± 0.3 ppmv and 4.9 ± 0.9 ppmv for the tropical mean stratospheric entry water vapor concentration and saturation mixing ratio, respectively, are well within previous estimates from a wide variety of observations. We also find that the interannual variability modes of the El Niño–Southern Oscillation (ENSO) and the quasi-biennial oscillation (QBO) both impact the tropopause region. The TWP (TCP) experiences enhancements (cancellation) of temperature anomalies when the ENSO and QBO are in phase. When these interannual modes fall out of phase the additive behavior of the anomalies migrate to the TCP with the TWP experiencing weaker anomalies. In both cases a change in the water vapor distribution is also observed. Our results are consistent with previous results, showing that this migration of anomaly enhancement and cancellation is a result of the ENSO impact on the Walker Circulation and the period when this occurs relative to the phase of the QBO. Our findings suggest that when the ENSO and QBO are out of phase, the TCP water vapor distribution may have a substantial impact on the tropical zonal water vapor distribution.

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