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The Tropical Subseasonal Variability Simulated in the NASA GISS General Circulation ModelThe tropical subseasonal variability simulated by the Goddard Institute for Space Studies general circulation model, Model E2, is examined. Several versions of Model E2 were developed with changes to the convective parameterization in order to improve the simulation of the Madden-Julian oscillation (MJO). When the convective scheme is modified to have a greater fractional entrainment rate, Model E2 is able to simulate MJO-like disturbances with proper spatial and temporal scales. Increasing the rate of rain reevaporation has additional positive impacts on the simulated MJO. The improvement in MJO simulation comes at the cost of increased biases in the mean state, consistent in structure and amplitude with those found in other GCMs when tuned to have a stronger MJO. By reinitializing a relatively poor-MJO version with restart files from a relatively better-MJO version, a series of 30-day integrations is constructed to examine the impacts of the parameterization changes on the organization of tropical convection. The poor-MJO version with smaller entrainment rate has a tendency to allow convection to be activated over a broader area and to reduce the contrast between dry and wet regimes so that tropical convection becomes less organized. Besides the MJO, the number of tropical-cyclone-like vortices simulated by the model is also affected by changes in the convection scheme. The model simulates a smaller number of such storms globally with a larger entrainment rate, while the number increases significantly with a greater rain reevaporation rate.
Document ID
20140001058
Acquisition Source
Goddard Space Flight Center
Document Type
Other
Authors
Kim, Daehyun
(Columbia Univ. Palisades, NY, United States)
Sobel, Adam H.
(Columbia Univ. Palisades, NY, United States)
DelGenio, Anthony D.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Chen, Yonghua
(Columbia Univ. New York, NY, United States)
Camargo, Suzana J.
(Columbia Univ. Palisades, NY, United States)
Yao, Mao-Sung
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Kelley, Maxwell
(Columbia Univ. New York, NY, United States)
Nazarenko, Larissa
(Columbia Univ. New York, NY, United States)
Date Acquired
March 6, 2014
Publication Date
July 1, 2012
Publication Information
Publication: Journal of Climate
Volume: 25
Issue: 13
Subject Category
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN9005
Funding Number(s)
CONTRACT_GRANT: NNX10AU63A
Distribution Limits
Public
Copyright
Public Use Permitted.
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