Priyanka Yadav (प्रियंका यादव)

I am a PhD student in the Climate Dynamics Doctoral Program at George Mason University. My research focuses on Predictability of mid-latitude circulation due to the interactions with the Madden Julian Oscillation (MJO). I am completing my dissertation under the direction of Prof. David M. Straus. My research interests includes understanding mechanisms that drive the tropical-extratropical interactions on intraseasonal time scales, large scale weather regimes, and tropical dynamics.

The tropical intraseasonal variations included in what we know as the Madden–Julian oscillation (MJO) encompass not only a broad band of eastward-propagating circulation anomalies, but large deep anomalies in diabatic heating and upper-level divergence. Tropical large-scale variations in the seasonal and intraseasonal timescales affect the extratropics. Different weather regimes in the Atlantic and Pacific develop in response to the MJO forcing. Thus, the MJO is a major source of predictability of the prominent modes in extratropics (e.g. Arctic Oscillation, North Atlantic Oscillation (NAO) and Pacific North American (PNA) pattern) in 3-4 weeks time scale.

Previous work on the extratropical response to the MJO has considered all MJO episodes without consideration of their phase speed. In the current work we distinguish Fast versus Slow MJO episodes, and study the extratropical response as seen from composites and frequencies of occurrence of circulation regimes for Northern Hemispheric winters. I am trying to understand the extratropical circulation response to different characteristics of the Madden-Julian Oscillation, in particular to the phase speed of the MJO, using both observational data and mechanistic experiments with the CFSv2 coupled model of NOAA in a reforecast environment using the technique of idealized MJO heating in a large ensemble.

My work on observational study using ERA-Interim data for 32 winters assesses the different remote response to Fast and Slow MJO episodes in terms of composite maps and frequency of occurrence of robust circulation regimes (pdf). I have done CFSv2 experiments in which the added heating is based on observational analysis but has been idealized, thus producing fast and slow MJO episodes with well-defined phase speeds. The availability of the added heating technique enables us to address important questions regarding the mechanisms and potential predictability of the MJO response in an operational forecasting model setting.