The Potential Predictability of Sub-Monthly Variability Over the Northwest Indian Ocean Rim Using the Madden Julian Oscillation

The Northwest Indian Ocean Rim, a region containing East Africa, the Arabian Peninsula and Southwest Asia, is strongly influenced by the Madden Julian Oscillation (MJO), the leading mode of tropical intraseasonal climate variability. Here we examine 1) the previously identified links between observed MJO events and the atmospheric circulation over the Northwest Indian Ocean Rim and 2) the ability to make quality one and two week precipitation forecasts over the Northwest Indian Ocean Rim using dynamical forecasts of the MJO.

One and two week precipitation and atmospheric circulation forecasts over the Northwest Indian Ocean Rim using the MJO are constructed in four steps: 1) Historical daily precipitation and atmospheric circulation composites are constructed as a function of eight MJO phases and four MJO amplitude ranges corresponding to weak, average, moderate, and strong MJO occurrences. 2) Forecasts of MJO amplitude and phase are drawn from the Global Forecast System (GFS) ensemble average. 3) Daily precipitation and atmospheric circulation forecasts are constructed by selecting the historical composite that corresponds to the forecast GFS MJO amplitude and phase. 4) Week one (days 1-7) and week two (days 8-14) forecasts of precipitation and circulation are created by averaging the daily forecasts. Week one and two forecasts are skillful in terms of precipitation and atmospheric circulation, but tend to produce extreme forecasts since internal atmospheric variability is ignored using this method.