Publication Abstracts

Kim et al. 2012

Kim, D., A.H. Sobel, A. Del Genio, Y. Chen, S.J. Camargo, M.-S. Yao, M. Kelley, and L. Nazarenko, 2012: The tropical subseasonal variability simulated in the NASA GISS general circulation model. J. Climate, 25, 4641-4659, doi:10.1175/JCLI-D-11-00447.1.

The tropical subseasonal variability simulated by the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 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). Consistent with previous studies, the simulation of the MJO is found to depend strongly on cumulus parameterization. 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 re-evaporation 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. MJO life-cycle composites of various model fields in a selected version of Model E2 demonstrate realistic features of the simulated MJO. By re-initializing 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 the 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 re-evaporation rate.

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BibTeX Citation

  author={Kim, D. and Sobel, A. H. and Del Genio, A. and Chen, Y. and Camargo, S. J. and Yao, M.-S. and Kelley, M. and Nazarenko, L.},
  title={The tropical subseasonal variability simulated in the NASA GISS general circulation model},
  journal={Journal of Climate},

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RIS Citation

ID  - ki05100g
AU  - Kim, D.
AU  - Sobel, A. H.
AU  - Del Genio, A.
AU  - Chen, Y.
AU  - Camargo, S. J.
AU  - Yao, M.-S.
AU  - Kelley, M.
AU  - Nazarenko, L.
PY  - 2012
TI  - The tropical subseasonal variability simulated in the NASA GISS general circulation model
JA  - J. Climate
JO  - Journal of Climate
VL  - 25
SP  - 4641
EP  - 4659
DO  - 10.1175/JCLI-D-11-00447.1
ER  -

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