Mesospheric responses to Madden–Julian Oscillation

Abstract:

The Madden–Julian Oscillation (MJO) is a dominant intra-seasonal variability in the equatorial troposphere, and is characterized by eastward propagation of tropical deep convection with a speed of ~ 5 m/s from Indian ocean to central Pacific ocean, and with a intra-seasonal period of 30-90 days [Madden and Julian, 1994]. The MJO could significantly impact the global weather and climate [Zhang, 2005]. Recent studies also suggested that the Northern Hemisphere (NH) stratospheric polar vortex could be modulated by the MJO with strengthened (weakened) polar vortex during the enhanced (suppressed) convection in the tropical central Pacific Ocean [Garfinkel et al., 2014]. Using the Aura/Microwave Limb Sounder (MLS) observations, Specified Dynamics of Whole Atmosphere Community Climate Model (SD-WACCM), and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis interim dataset datasets, we study the MJO impacts in the stratosphere and mesosphere. During the MJO phase 7 when the deep convection propagates to the central Pacific Ocean, we see in both satellite observation and SD-WACCM simulation the NH stratosphere polar temperature warming and mesosphere cooling. The opposite temperature anomalous pattern is seen in the equatorial region. We will discuss the mechanism of the mesosphere responses to MJO using SD-WACCM and ECMWF.