Stratospheric drain over Indonesia and dehydration within the tropical tropopause layer diagnosed by air parcel trajectories

61Citations
Citations of this article
29Readers
Mendeley users who have this article in their library.

Abstract

The structures of temperature and velocity fields in the tropical tropopause layer (TTL) in boreal winter are investigated using an atmospheric general circulation model (AGCM). The model reveals strong upward motions in the lower part of the TTL over the maritime continent and the western tropical Pacific, corresponding to the "stratospheric fountain" region, and downward motions in the upper part of the TTL over Indonesia, representing the stratospheric drain. In the TTL, strong easterlies prevail, and the cold ascent region tilts eastward. A down-slope flow over the upward-bulging isentropic surface produces the downward p velocity over Indonesia. In addition, reduction of longwave heating over deep convection suppresses the upward motion. The model simulates the observed stratospheric drain signature well, without convective overshootings. A trajectory analysis using the AGCM-simulated three-dimensional wind and temperature is performed to clarify the entry process of air parcels from the tropical troposphere to the stratosphere and to investigate the dehydration process during passage through the TTL. Tropospheric air parcels are advected upward to the bottom of the TTL mainly from the stratospheric fountain region. A pair of anticyclonic circulations in the tropical western Pacific entrains air parcels, which then pass through the equatorial cold region several times during the slow ascent in the TTL. This slow spirally ascending motion brings about low humidity in the stratosphere, despite the local downward motion over Indonesia. In addition, transient disturbances, particularly low-frequency disturbances, produce intermittent upward motions over the fountain region, resulting in effective dehydration of the air. The spiral ascent and transient mechanisms are key factors in the dehydration process in the TTL. The interannual variation in the water vapor mixing ratio into the tropical lower stratosphere with the El Nino/Southern Oscillation cycle is also estimated, and it is found that in La Nina years, air is more dehydrated.

References Powered by Scopus

Some simple solutions for heat‐induced tropical circulation

3795Citations
N/AReaders
Get full text

Relaxed Arakawa-Schubert: a parameterization of moist convection for general circulation models

890Citations
N/AReaders
Get full text

The tropical tropopause

420Citations
N/AReaders
Get full text

Cited by Powered by Scopus

Tropical tropopause layer

744Citations
N/AReaders
Get full text

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

270Citations
N/AReaders
Get full text

Stratospheric water vapor predicted from the Lagrangian temperature history of air entering the stratosphere in the tropics

198Citations
N/AReaders
Get full text

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Cite

CITATION STYLE

APA

Hatsushika, H., & Yamazaki, K. (2003). Stratospheric drain over Indonesia and dehydration within the tropical tropopause layer diagnosed by air parcel trajectories. Journal of Geophysical Research: Atmospheres, 108(19). https://doi.org/10.1029/2002jd002986

Readers' Seniority

Tooltip

PhD / Post grad / Masters / Doc 10

45%

Researcher 9

41%

Professor / Associate Prof. 2

9%

Lecturer / Post doc 1

5%

Readers' Discipline

Tooltip

Earth and Planetary Sciences 17

77%

Physics and Astronomy 2

9%

Environmental Science 2

9%

Decision Sciences 1

5%

Save time finding and organizing research with Mendeley

Sign up for free