MJO Experimental Prediction Project:
Project History
Two NASA/USCLIVAR-sponsored workshops held in Spring 2002, 2003 explored the potential for improved forecasts of weather and short-term climate variability on subseasonal time scales. Several sources of unrealized predictability were identified including tropical heating, soil moisture, the Madden-Julian Oscillation (MJO), the Arctic Oscillation and the Pacific/North American pattern. The second workshop focused on issues related to the MJO and tropical- extratropical interaction as they relate to the subseasonal simulation and prediction problem. As part of a strategy to assess current model subseasonal prediction capabilities and shortcomings, an experimental forecast and model development program was proposed that focuses on one of the key sources of untapped predictability, namely the MJO. Several multinational forecast agencies and empirical modelers expressed interest in contributing near real time forecasts to a website that would display similar fields at similar lead times and in a common graphics format.
References:
Schubert, S., R. Dole, H. v.d. Dool, M. Suarez and D.Walliser, 2002: Proceedings from a Workshop on "Prospects for Improved forecasts of Weather and Short-term Climate Variability on Subseasonal (2 week to 2 month) Time Scales", 16-18 April 2002, Mitchellville, MD, NASA/TM 2002-104606, vol. 23, 171 pp.
Walliser, D., S. Schubert, A. Kumar, K. WEickmann and R. Dole, 2003: Proceedings from a workshop on "Modeling, Simulation and Forecasting of Subseasonal Variability", 4-5 June 2003, University of Maryland, College Park, Maryland, NASA/CP 2003-104606, vol25, 62 pp.
Project Description
The primary objective of the project is the delivery of skillful predictions, with lead times of 1-4 weeks, of tropical and extratropical intraseasonal variability. In terms of directly predicting tropical variability at these lead times, it is recognized that the state of the Madden-Julian Oscillation (MJO) and its evolution is crucially important. In regards to extratropical forecasts, the skillful prediction of the MJO is perceived to be somewhat, or at least intermittently, important for extratropical weather forecasts during weeks 1-2. At lead times of 3 to 4 weeks, the prediction of the MJO may be helpful in foreshadowing large scale circulation changes in the extratropical flow.
In both the tropical and extratropical cases, skillful MJO forecasts could lead to useful predictive information on the probability of extreme events ( NOAA hazards assessment page). A secondary objective is to assess in real time a general circulation models’ ability to predict extreme events and pattern transitions with lead times of 3 to 11 days. These sometimes involve tropical-extratropical interactions related to the MJO but more generally involve variability on all time scales. As a result, the role of other phenomena such a baroclinic wave packets and transient orographic forcing will be monitored and assessed. For the MJO, the project is interested in the details of how the composite patterns that are linked with the MJO develop and become persistent. This involves monitoring the daily ensemble predictions including the models’ handling of individual weather systems.
Once it can be established that useful forecast skill can be derived from the contributing models, whether empirical or dynamical, efforts will be made to incorporate this information into formal week 2 and monthly predictions from the forecast agencies. In addition, the forecast and diagnostic information provided by the project would more easily provide a means to routinely diagnose, and provide some attribution of, subseasonal weather/climate anomalies. Finally, apart from exploiting the project for the prediction purposes outlined above, it is intended to also serve as a basis for model intercomparison studies.This includes using the forecasts and biases in model error growth or MJO signal as a means to learn more about, and possibly rectify, model shortcomings associated with the MJO.