Abstract 191

Abstract ID: 191

The Maritime Continent barrier effect on MJO predictability: perfect-model ensemble forecasts with the CESM2 aqua-planet

Lead Author: Hyemi Kim
Stony Brook University, United States of America

Keywords: MJO predictability, Maritime Continent barrier effect, Idealized aqua-planet experiment, Ensemble forecast experiment

Abstract: Studies have indicated exaggerated Maritime Continent (MC) barrier effect in simulations of the Madden-Julian oscillation (MJO), a dominant source of subseasonal predictability in the tropics. This issue has plagued the modeling and operational forecasting communities for decades, while the sensitivity of MC barrier on MJO predictability has not been addressed quantitatively. In this study, perfect-model ensemble forecasts are conducted with an aqua-planet configuration of the Community Earth System Model Version 2 (CESM2) in which both basic state and tropical modes of variability are reasonably simulated with a Warm Pool-like SST distribution. When water-covered terrain mimicking MC land masses (MC barrier) is added to the Warm Pool-like SST framework, the eastward propagation of the MJO is disturbed by the prescribed MC aqua-mountain. We will show the predictability change by the MC barrier effect in the idealized model experiment.

James J. Benedict (Los Alamos National Laboratory, USA)