Changes in the metastability of the Southern Hemisphere 500-hPa circulation are examined using both cluster analysis techniques and split-flow blocking indices. The cluster methodology is a purely data-driven approach for parameterization whereby a multiscale approximation to nonstationary dynamical processes is achieved through optimal sequences of locally stationary fast vector autoregressive factor (VARX) processes and some slow (or persistent) hidden process switching between them. Comparison is made with blocking indices commonly used in weather forecasting and climate analysis to identify dynamically relevant metastable regimes in the 500-hPa circulation in both reanalysis and Atmospheric Model Intercomparison Project (AMIP) datasets. The analysis characterizes the metastable regime in both reanalysis and model datasets prior to 1978 as positive and negative phases of a hemispheric midlatitude blocking state with the southern annular mode (SAM) associated with a transition state. Post-1978, the SAM emerges as a true metastable state replacing the negative phase of the hemispheric blocking pattern. The hidden state frequency of occurrences exhibits strong trends. The blocking pattern dominates in the early 1980s, and then gradually decreases. There is a corresponding increase in the SAM frequency of occurrence. This trend is largely evident in the reanalysis summer and spring but was not evident in the AMIP dataset. Further comparison with the split-flow blocking indices reveals a superficial correspondence between the cluster hidden state frequency of occurrences and split-flow indices. Examination of composite states shows that the blocking indices capture splitting of the zonal flow whereas the cluster composites reflect coherent block formation. Differences in blocking climatologies from the respective methods are discussed.
The entries are in, the judging has begun and preparations are well under way for this year’s Baking Industry Awards evening. Staged at the prestigious Grosvenor House hotel in London on 18 September, the Awards will pay tribute to some of the finest talent that UK bakeries have to offer, from enthusiastic students to this year’s Baker of the Year, often a seasoned individual. Three finalists in each category will be called up to the stage to receive their certificates and, in the case of the winner, a £500 cheque and trophy from a celebrity host.But the evening is not just about recognising excellence. It’s also a chance to rub shoulders with colleagues from across the UK and Ireland, catch up with old friends, exchange ideas and, last but by no means least, have a lot of fun. The evening includes a Champagne reception, four-course dinner with wine, a cabaret, disco and dancing and a casino, as well as a quieter bar area for networking or just having a chat.With plenty of opportunities to win prizes and raise money for charity, the Baking Industry Awards evening is also a unique opportunity to give something back to the industry that employs you. Around 900 people attended the Awards last year and tickets for this year’s event are already sel-ling quickly. So don’t delay! Call Liz Ellis on our ticket hotline (see box) to make sure you don’t miss out.