MASS Seminar - Chidong Zhang (Miami)
Date |
Time |
Location |
May 9th, 2011 |
12:00pm-1:00pm |
54-915 |
Potential Vorticity of the Madden-Julian Oscillation and Equatorial Waves
Potential Vorticity (PV) is used as a diagnostic tool to explore the three-dimensional dynamical and thermodynamical structure of the Madden-Julian Oscillation (MJO) in comparison to equatorial waves. Structures of PV and diabatic heating of the MJO are distinct from those of the equatorial Kelvin and Rossby waves. PV generation of the MJO is dominated by MJO diabatic heating acting on planetary vorticity and interaction between diabatic heating and relative vorticity of non-MJO perturbations. In this latter MJO PV generation process, no identifiable role by the equatorial Kelvin and Rossby waves is found. From a PV point of view, thus, the MJO is maintained by a combination of self-sustaining and stochastic scale-interaction processes independent of the equatorial Kelvin and Rossby waves. Over the tropical Indian Ocean, main features in PV generation of the MJO during its initiation include strong pre-existing anticyclonic PV associated with negative anomalies of diabatic heating prior to the emergence of positive anomalies of diabatic heating. This suggests a possible precursor for prediction of MJO initiation.
http://metofis.rsmas.miami.edu/~czhang/