Premium
An alternative mechanism explaining the hygropause formation in tropical regions
Author(s) -
Teitelbaum H.,
Moustaoui M.,
Basdevant C.,
Holton J. R.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl010874
Subject(s) - tropopause , radiosonde , stratosphere , water vapor , atmospheric sciences , convection , mixing ratio , altitude (triangle) , lapse rate , environmental science , climatology , troposphere , potential temperature , mixing (physics) , meteorology , geology , physics , mathematics , geometry , quantum mechanics
Radiosonde data obtained during CEPEX and TOGA‐COARE experiments show that a very simple mechanism can explain the existence, in tropical regions, of a local hygropause with a very low water vapor mixing ratio, less than 2 ppmv. This mechanism explains also why this hygropause is generally located well above the average tropopause in the lower stratosphere, and why it can temporarily coincide with the local tropopause. This interpretation is based on the existence, during periods of intense convective phenomena, of an uplift of the tropopause inducing a cooling of its temperature. We indeed find in these circumstances, when temperature and water vapor measurements are simultaneously available, very low water vapor values at the same level as the temperature minimum. After the end of the intense convection episode, the minimum temperature level is reestablished at a lower altitude while the hygropause remains positioned in the lower stratosphere but with a low value for the water vapor mixing ratio.