Impacts of Cumulus Convection Parameterization on Aqua-planet AGCM Simulations of Tropical Intraseasonal Variability

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概要

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• Using an aqua-planet version of an atmospheric general circulation model (AGCM), the dependence of the tropical intraseasonal oscillation (ISO) simulation on the cumulus parameterization was examined with three different cumulus schemes-simplified Arakawa-Schubert, Kuo, and moist convective adjustment. The simulated intensity and propagation characteristics of the ISO depend significantly on the choice of cumulus scheme, in which more constrained convection scheme produces stronger intraseasonal variability in tropics. Mean thermodynamic state and the Intertropical Convergence Zone (ITCZ) structure also vary among the simulations, demonstrating that the ISO variability and the mean states are mutually dependent. Following Tokioka et al. (1988), the simplified Arakawa-Schubert scheme was modified by posing a minimum entrainment rate constraint for cumuli, and the relationship between tropical intraseasonal variability and zonal mean rainfall structure was examined. More constraining deep convections, the tropical ISO variability becomes stronger with narrower ITCZ structures. Vertical and horizontal structures of eastward propagating waves appeared in the aqua-planet experiments were further investigated. The vertical structures of propagating waves are consistent with observations of the Madden-Julian Oscillation, but the vertical profile of ISO-modulated heating exhibits a middle-heavy structure and the simulated waves show relatively faster propagations compared with the observed. The horizontal composite structures show the boundary-layer moisture frictional convergence to the east, and divergence to the west of the convective region, and this suggests that a frictional Kelvin wave-CISK mechanism is important to these eastward propagating waves.

• 社団法人日本気象学会の論文
• 2003-10-27

著者

• Mapes Brian

  Noaa-cires Climate Diagnostics Center

• Kang I‐s

  Seoul National Univ. Seoul Kor

• Kang In-sik

  School Of Earth Environment Sciences Seoul National University

• LEE Myong-In

  Climate Environment System Research Center, Seoul National University

• Lee Myong-in

  Climate Environment System Research Center Seoul National University:(present Address)goddard Earth

• Kang In-Sik

  School of Earth and Environmental Sciences, Seoul National University

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• Impacts of Cumulus Convection Parameterization on Aqua-planet AGCM Simulations of Tropical Intraseasonal Variability
• A Systematic Approximation of the SST Anomaly Equation for ENSO

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