MJO Propagation and Its Influence on Temperature and Precipitation over the United States

Characteristics of cold-season (November – March) daily temperature and precipitation over the contiguous US during different phases of the Madden-Julian Oscillation (MJO) have been analyzed in many previous studies. In this work, we extend these previous studies to investigate the influence of how MJO-associated convection is developed, for example, initiated locally or propagated from the west. We focus on the US temperature and precipitation anomalies corresponding to MJO-associated convection in the Western Pacific (WP) and compare between cases when convection was propagated from the Indian Ocean and Maritime Continent with cases when convection was developed locally in the WP. The MJO is categorized into four propagation events based on the Wheeler-Hendon index. The first is convection that initiates in the Indian Ocean (IO: Phase 2/3) and propagates to the WP (Phase 6/7). The second event type is convection that initiates in the IO and propagates into the Maritime Continent (MC: Phase 4/5). Third is initiation in the MC with propagation into the WP, and finally convection that initiates and stays in the WP. From these events, daily temperature and precipitation are composited over the US to explore if there are any differences in influence patterns due to the different propagation patterns. The analysis will be based on surface temperature from ERA-Interim analysis and precipitation from Climate Prediction Center (CPC) CMORPH analysis. Forecasts from the Climate Forecast System (CFS) will also be assessed.