Title: A mechanism-denial study on the Madden-Julian Oscillation with reduced interference from mean state changes

Abstract

In this paper, mechanism-denial experiments using Superparameterized Community Atmosphere Model are conducted to investigate the importance of extratropical and circumnavigating waves, wind-evaporation feedback, and radiative-convective feedback to the Madden-Julian Oscillation (MJO). A common issue with mechanism-denial studies is the interference from mean state changes when processes are turned off in the model. Here time-invariant forcing and nudging on effective timescales longer than the intraseasonal timescale are implemented to maintain the mean state. The MJO activity remains largely unchanged with suppressed extratropical and circumnavigating waves when the mean state is maintained to be close to that of the control run, suggesting that excitation of MJO by extratropical and circumnavigating waves is not necessary for the existence of MJO in this model. Finally, it is also shown that the wind-evaporation feedback slows down eastward propagation of the MJO, and the radiative-convective feedback amplifies the MJO.

Authors:

Ma, D. ^[1]; Kuang, Z. ^[2]

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+ Show Author Affiliations

1. Harvard Univ., Cambridge, MA (United States). Dept. of Earth and Planetary Sciences
2. Harvard Univ., Cambridge, MA (United States). Dept. of Earth and Planetary Sciences. School of Engineering and Applied Sciences

Publication Date:

2016-02-12

Research Org.:

Harvard Univ., Cambridge, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Aeronautic and Space Administration (NASA)

OSTI Identifier:

1469182

Alternate Identifier(s):

OSTI ID: 1402161

Grant/Contract Number:  

SC0008464; NNX13AN47

Resource Type:

Accepted Manuscript

Journal Name:

Geophysical Research Letters

Additional Journal Information:

Journal Volume: 43; Journal Issue: 6; Journal ID: ISSN 0094-8276

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; MJO; mechanism-denial study; extratropical waves; circumnavigating waves; wind-evaporation feedback; radiative-convective feedback