Climate Hazards Group Seminar: Key Processes in Modeling the Madden-Julian Oscillation



12/01/2017 - 12:00pm to 12/02/2017 - 11:45am


Dr. Xianan Jiang

The December climate meeting will be a single talk this time:

Presenter: Dr. Xianan Jiang

Title: Key Processes in Modeling the Madden-Julian Oscillation

Affiliation: Joint Institute for Regional Earth System Science & Engineering, UCLA & Jet Propulsion Laboratory, California Institute of Technology


 Despite its tremendous influences on global weather extremes, representation of the Madden-Julian oscillation (MJO) remains a grand challenge for present-day climate models. In this talk, a brief overview of critical issues of the MJO will be provided. Critical findings of key processes in regulating MJO amplitude and propagation will then be presented by analyzing multi-model simulations from the recent MJO Task Force / GEWEX GASS MJO model comparison project, under a moisture-mode theoretical framework recently proposed for the MJO. The efficiency of precipitation generation per unit column water vapor, or the convective time-scale, is found to be closely linked to model MJO amplitude. On the other hand, moistening and drying due to horizontal advection of lower-tropospheric seasonal mean moisture are critical in driving the eastward propagation of the MJO. Faithful model simulation of the low-level (900-650hPa) mean moisture pattern over the Indo-Pacific region, particularly near the Maritime Continent area, is further found to be essential for realistic representation of the MJO eastward propagation in climate models.


Short bio:
Dr. Xianan Jiang is a researcher at the Joint Institute for Regional Earth System Science and Engineering between UCLA and Jet Propulsion Laboratory. His primary research interest is to explore key dynamics and physics governing atmospheric convective activity on various temporal and spatial scales. In particular, one of his current research topics focuses on the Madden-Julian Oscillation (MJO) and associated extreme weather activity. He is the principal investigator of a climate process team for “Understanding MJO Initiation and Propagation”, sponsored by the NOAA Climate Project Office. He is an editor for the journal of Dynamics of Atmospheres and Oceans. His educational background includes a Ph.D. in Atmospheric Sciences from University of Hawaii, and a postdoctoral position at NOAA’s Geophysical Fluid Dynamics Laboratory.