HR: 13:40h
AN: A53B-01    [Abstracts]
TI: Modeling the Madden-Julian Oscillation in the East Pacific
AU: * Raymond, D J
EM: raymond@kestrel.nmt.edu
AF: Physics Dept. New Mexico Tech, 801 Leroy Place, Socorro, NM 87801 United States
AB: Raymond (2001) developed a numerical model of the Madden-Julian oscillation (MJO) which has many realistic aspects. Here we apply a new version of this model to an equatorial beta plane aqua-planet using Reynolds sea surface temperatures (with land values obtained by interpolation from ocean values according the the scheme of Reynolds) for the period of the EPIC2001 field program (September-October 2001). MJO-like disturbances propagate eastward in the model with a speed of 4-5 m/s. The simulated variability in the tropical East Pacific resembles that observed during EPIC. In particular, the easterly wind phase of the MJO is accompanied by little or no precipitation and a weak, shallow Hadley circulation (Zhang et al., 2004), whereas the westerly phase exhibits a strong, deep Hadley cell and intense precipitation. Unlike the case in many global models, the simulated MJO in the present model is stronger than that actually observed. However, the qualitative agreement with observation suggests that the atmospheric circulation in the East Pacific is inherently three-dimensional and time-dependent, with the MJO playing a major role in controlling its characteristics. A two-dimensional y-z plane version of the model using the Reynolds sea surface temperature distribution at 90 W does not capture the essential behavior of the circulation in the East Pacific. References Raymond, D. J., 2001: A new model of the Madden-Julian oscillation. J. Atmos. Sci., 58, 2807-2819. Zhang, C., M. McGauley, and N. A. Bond, 2004: Shallow meridional circulation in the tropical eastern Pacific. J. Climate, 17, 133-139.
DE: 3314 Convective processes
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3367 Theoretical modeling
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005