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

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:
 [1] ;  [2]
  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:
Grant/Contract Number:
SC0008464; NNX13AN47
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
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)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; MJO; mechanism-denial study; extratropical waves; circumnavigating waves; wind-evaporation feedback; radiative-convective feedback
OSTI Identifier:
1469182
Alternate Identifier(s):
OSTI ID: 1402161

Ma, D., and Kuang, Z.. A mechanism-denial study on the Madden-Julian Oscillation with reduced interference from mean state changes. United States: N. p., Web. doi:10.1002/2016GL067702.
Ma, D., & Kuang, Z.. A mechanism-denial study on the Madden-Julian Oscillation with reduced interference from mean state changes. United States. doi:10.1002/2016GL067702.
Ma, D., and Kuang, Z.. 2016. "A mechanism-denial study on the Madden-Julian Oscillation with reduced interference from mean state changes". United States. doi:10.1002/2016GL067702. https://www.osti.gov/servlets/purl/1469182.
@article{osti_1469182,
title = {A mechanism-denial study on the Madden-Julian Oscillation with reduced interference from mean state changes},
author = {Ma, D. and Kuang, Z.},
abstractNote = {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.},
doi = {10.1002/2016GL067702},
journal = {Geophysical Research Letters},
number = 6,
volume = 43,
place = {United States},
year = {2016},
month = {2}
}