Intraseasonal variations of water vapor in the tropical upper troposphere and tropopause region

Philip W. Mote*, Hannah L. Clark, Timothy J. Dunkerton, Robert S. Harwood, Hugh C. Pumphrey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We show the signature of the tropical intraseasonal oscillation (TIO) in upper tropospheric moisture and dynamical fields, roughly between 200 and 100 hPa. Relationships among these fields are examined using lag-correlation analysis and using multivariate extended empirical orthogonal functions (MEEOFs), which maximize the shared explained variance among several fields for both spatial and temporal variations. The MEEOFs show that all of the fields respond to the TIO and that the TIO is the dominant factor influencing each of the fields on these timescales. Convection associated with the TIO moistens the upper troposphere up to about 150 hPa, as expected; the behavior at 100 hPa is more complex. Over the longitude range where the TIO is associated with convection, roughly 60°-180°E, 100-hPa temperature and water vapor tend to be reduced above convection on TIO timescales. East of 180°, though, the temperature and water vapor variations at 100 hPa become decoupled. The water vapor variations, like those of 200-hPa velocity potential, appear to speed up at about 180°E.

Original languageEnglish
Article number2000JD900158
Pages (from-to)17457-17470
Number of pages14
JournalJournal of Geophysical Research Atmospheres
Issue numberD13
Publication statusPublished - 16 Jul 2000


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