Atmos. Chem. Phys. Discuss., 12, 11567-11594, 2012
© Author(s) 2012. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Height increase of the melting level stability anomaly in the tropics
I. Folkins
Department of Physics and Atmospheric Science, Dalhousie University Halifax, B3H 3J5, Nova Scotia, Canada

Abstract. In actively convecting regions of the tropics, the lower troposphere is significantly less stable than predicted by a moist pseudoadiabat. This anomalous variation in lapse rate occurs between the boundary layer inversion (~2 km) and the melting level (~5 km), and has been attributed to mesoscale downdrafts that develop below precipitating stratiform anvil clouds. We use an 11 yr record (1998–2008) from five Western Tropical Pacific radiosonde stations in the Stratospheric Processes and their Role in Climate (SPARC) archive, to determine the response of this stability anomaly to changes in monthly mean surface temperature. We find that the stability anomaly shifts upward when the surface temperature increases, by an amount roughly equal to the upward displacement of the melting level. It is likely that this change in lower tropospheric stability is associated with increases in the height of cumulus congestus clouds, in the vertical distance through which stratiform precipitation falls through cloud free air, and in the vertical wavelength of the stratiform heating mode.

Citation: Folkins, I.: Height increase of the melting level stability anomaly in the tropics, Atmos. Chem. Phys. Discuss., 12, 11567-11594, doi:10.5194/acpd-12-11567-2012, 2012.
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