Mechanisms controlling water vapor in the lower stratosphere: “A tale of two stratospheres”
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We present an analysis of the mechanisms controlling stratospheric water vapor based on in situ profiles made at 36.4°N and at altitudes up to 20 km. The stratosphere can be conveniently divided into two air masses: the overworld (potential temperature θ<380). Our data support the canonical theory that air primarily enters the overworld by passing through the tropical tropopause. Air parcels crossing the extratropical tropopause experience higher temperatures, allowing higher water vapor in the lowermost stratosphere (tens of ppmv) than in the overworld. Our data are consistent with the pathway for air crossing the extratropical tropopause being isentropic advection from lower latitudes. -from Authors
author list (cited authors)
Dessler, A. E., Hintsa, E. J., Weinstock, E. M., Anderson, J. G., & Chan, K. R.