报告题目：Long range predictability of the atmosphere
报告人：Professor Adam A. Scaife（Met Office and University of Exeter, UK）
地点：大气楼D103报告厅
报告摘要：
Our understanding of mechanisms for long range predictability of regional climate is centred on the highly predictable tropical atmosphere. Not least from ENSO, the high seasonal to interannual predictability of the tropics and associated stationary waves that propagate out of the tropics into the extratropics, provide much of the current basis for global long range predictability.
We show in this talk that in addition to stationary waves, there are also zonally symmetric predictable signals within the atmospheric circulation that migrate slowly and predictably out of the tropics and into the extratropics. These signatures have remarkably long timescales of around a year and are linked to changes in atmospheric angular momentum and hence the length of day. They are often triggered by ENSO but persist long after ENSO events have decayed in the spring. We show how they lead to ENSO teleconnections in the extratropics a whole year after the ENSO event itself.
We describe our proposed mechanism for these slow propagating signals. We show that transient eddies, propagating equatorwards from the mid latitudes and then undergoing wave-mean flow interaction, drive the poleward migration of angular momentum anomalies towards the extratropical wave source. This process explains the incredibly long timescale, long range predictability and other features of this remarkable atmospheric phenomenon.
The implications of these findings are not yet fully understood but we show how it can help to explain the lagged effects of ENSO on the East Asian monsoon and how coherent propagation of the angular momentum anomalies may be important for long range predictability of the summer monsoon as well as the North Atlantic Oscillation.
报告人简介:
Professor Adam Scaife leads research and production of long-range forecasts at the Met Office in the UK and is a Professor at the University of Exeter. His group issues climate forecasts on a regular basis and carries out research to improve seasonal to decadal predictions. Adam's personal research is focused on mechanisms, modelling and predictability of regional climate and his research group have demonstrated skilful seasonal prediction of the surface North Atlantic Oscillation and European winters that originates in the tropics and the stratosphere. They also uncovered the paradox that current climate models are better at predicting the real world than they are at predicting themselves, now known as the ‘signal-to-noise paradox’.
Adam has published over 300 research papers, academic and popular science books and provided science advice in many public outreach articles in newspapers, online, TV and radio. He was co-chair of the World Meteorological Organisation's Working Group on Seasonal to Interannual Prediction and the WCRP Grand Challenge on Near Term Climate Prediction. In recent years, Adam was awarded the Institute of Physics Edward Appleton Medal and the Royal Meteorological Society Buchan prize.
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