Sensitivity of the QBO to Mean Tropical Upwelling under a Changing Climate Simulated with an Earth System Model | Health & Environmental Research Online (HERO)

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Citation
Tags

HERO ID

4317503

Reference Type

Journal Article

Title

Sensitivity of the QBO to Mean Tropical Upwelling under a Changing Climate Simulated with an Earth System Model

Author(s)

Watanabe, S; Kawatani, Y

Year

2012

Is Peer Reviewed?

Yes

Journal

Journal of the Meteorological Society of Japan
ISSN: 0026-1165

Volume

90A

Page Numbers

351-360

DOI

10.2151/jmsj.2012-A20

Web of Science Id

WOS:000304385900021

Abstract

The sensitivity of the equatorial quasi-biennial oscillation (QBO) to increasing greenhouse gas (GHG) concentrations over time is evaluated using a high-top (85 km) earth system model, which generates the QBO using a non-orographic gravity wave drag parameterization. Based on a pre-industrial control run (1850), a 1/2 CO2 run and a 4 x CO2 run are performed as sensitivity experiments. In addition, long-term transient behaviors of the QBO in a historical climate run (1850-2005) and a future projection run (2006-2100) are investigated. The period of the simulated QBO lengthens in a GHG-rich warmer climate, changing from a quasi-regular 24 months in 1850-1980 to a variable 24-31 months in 1980-2050, although never exceeding 31 months even in the extremely warm 4 x CO2 run. Such elongation of the QBO period is mostly caused by strengthening of the mean tropical upwelling of the Brewer-Dobson circulation, which counteracts the wave forcing that drives the QBO. Simultaneous reductions in the easterly wind maximum of the QBO are also caused by this mechanism.