Tropical tropopause layer

Stephan Andreas Fueglistaler, A. E. Dessler, T. J. Dunkerton, I. Folkins, Q. Fu, P. W. Mote

Research output: Contribution to journalReview articlepeer-review

733 Scopus citations


Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp "tropopause." In the tropics, this layer is often called the "tropical tropopause layer" (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its timevarying, three-dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a "gate" to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate.

Original languageEnglish (US)
Article numberRG1004
JournalReviews of Geophysics
Issue number1
StatePublished - Mar 2009

All Science Journal Classification (ASJC) codes

  • Geophysics


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