A33R-06
Resilience of an explicitly simulated Madden-Julian Oscillation to extreme basic state variation challenges moisture mode view
Wednesday, 16 December 2015: 14:55
3012 (Moscone West)
Michael S Pritchard, University of California Irvine, Irvine, CA, United States and Da Yang, University of California Berkeley, Berkeley, CA, United States
Abstract:
Idealized experiments are performed with the SuperParamaterized CAM to test two hypotheses motivated by a modern view of the “moisture mode” theory of the Madden Julian Oscillation. Inconsistent with both hypotheses, evidence is found of a cold-MJO signal under horizontally homogenous SSTs. Apparently the intrinsic MJO signal in SPCAM3 is a surprisingly resilient mode that can survive both extreme cooling of the climate and a reversal of near-equatorial meridional MSE gradients. Column MSE analysis indicates a negative overall growth rate of MJO MSE in our coldest simulations, which is hard to reconcile with the survival of a cold MJO from a moisture mode view. A resilience of familiar features of the MJO-MSE budget in our simulations could indicate some other cause, beyond local column MSE dynamics, requires such phase relationships to exist.
