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Role of Longwave Cloud-Radiation Feedback in the Simulation of the Madden-Julian OscillationThe role of the cloud-radiation interaction in the simulation of the Madden-Julian oscillation (MJO) is investigated. A special focus is on the enhancement of column-integrated diabatic heating due to the greenhouse effects of clouds and moisture in the region of anomalous convection. The degree of this enhancement, the greenhouse enhancement factor (GEF), is measured at different precipitation anomaly regimes as the negative ratio of anomalous outgoing longwave radiation to anomalous precipitation. Observations show that the GEF varies significantly with precipitation anomaly and with the MJO cycle. The greenhouse enhancement is greater in weak precipitation anomaly regimes and its effectiveness decreases monotonically with increasing precipitation anomaly. The GEF also amplifies locally when convection is strengthened in association with the MJO, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). A robust statistical relationship is found among CMIP5 climate model simulations between the GEF and the MJO simulation fidelity. Models that simulate a stronger MJO also simulate a greater GEF, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). Models with a greater GEF in the strong precipitation anomaly regime (greater than 30 mm day(-1)) represent a slightly slower MJO propagation speed. Many models that lack the MJO underestimate the GEF in general and in particular in the weak precipitation anomaly regime. The results herein highlight that the cloud-radiation interaction is a crucial process for climate models to correctly represent the MJO.
Document ID
20160001401
Document Type
Reprint (Version printed in journal)
Authors
Kim, Daehyun (Washington Univ. Seattle, WA, United States)
Ahn, Min-Seop (Seoul National Univ. Korea, Republic of)
Kang, In-Sik (Seoul National Univ. Korea, Republic of)
Del Genio, Anthony D. (NASA Goddard Inst. for Space Studies New York, NY United States)
Date Acquired
February 2, 2016
Publication Date
September 1, 2015
Publication Information
Publication: Journal of Climate
Volume: 28
Issue: 17
Subject Category
Meteorology and Climatology
Report/Patent Number
GSFC-E-DAA-TN25580
Funding Number(s)
CONTRACT_GRANT: NRF-2012M1A2A2671775
CONTRACT_GRANT: CATER 2013-3142
WBS: WBS 573945.04.18.02.41
CONTRACT_GRANT: NNX13AM18G
Distribution Limits
Public
Copyright
Other
Keywords
Clouds
Long wave radiation
Computer modelling
Madden-Julian Oscillation