Sub-Seasonal Predictability And Dynamical Processes: Long-Range Interactions
Abstract
World leading global forecasting systems in 2016 operate with around 20-100 ensemble members and a horizontal resolution in the range 13 to 50km with of order 100 vertical levels. We can currently predict large-scale weather patterns and regime transitions out to a month or more ahead and high-impact events, such as tropical cyclones, out to two weeks ahead. Under certain conditions, even sub-seasonal to seasonal forecasts have some predictive skill. Especially the intra-seasonal variability has a lot more degrees of freedom than seasonal variability and the associated dynamical and physical processes are numerous and complex. As an example research in the last three decades on tropical modes of ocean-atmosphere interaction, like the El Nino/Southern Oscillation (ENSO) oceanic phenomenon and its complex interaction between the large scale tropical atmosphere and organised moist convection, has permitted significant advances in seasonal prediction. Similarly research in the intra-seasonal variability has point out another ocean-atmosphere interaction mode, the Madden-Julian Oscillation (MJO), as an important source of predictability. MJO modulates significantly the mid-latitude intra-seasonal variability through tropical and mid-latitude teleconnections, like the Canadian winter temperature and precipitation. Another example is the two-way link between the MJO and the North Atlantic Oscillation (NAO) modulates significantly weather regimes over Western Europe. Pushing forecast leadtime to sub-seasonal scale will unfold a new landscape of predictability, model uncertainties and ensemble prediction issues. The richness of the sources of predictability associated with these processes could provide increase predictive skill in all seasons and regions. The associated socio-economic benefits are indeed promising to inform reliably the risk of high-impact weather, including tropical cyclones, droughts, floods, heat waves and the waxing and waning of monsoon precipitation. In this talk we will do an overview of the different long range interactions that could be exploited for increasing the skill of sub-seasonal prediction.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A11K0159B
- Keywords:
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- 3319 General circulation;
- ATMOSPHERIC PROCESSESDE: 3362 Stratosphere/troposphere interactions;
- ATMOSPHERIC PROCESSESDE: 3367 Theoretical modeling;
- ATMOSPHERIC PROCESSESDE: 3373 Tropical dynamics;
- ATMOSPHERIC PROCESSES