Wind forecasts for the 2000 Olympic Games in Sydney with a Focus on Sydney Harbour

The Bureau of Meteorology will be providing forecasts for the Games of the XXVII Olympiad to be held in Sydney in September 2000 and the associated Paralympic Games in October 2000. One important aspect is to provide detailed spatial and temporal forecasts for the sailing events on Sydney Harbour. Since September 1997 detailed wind measurements have been provided at ten locations in and around Sydney Harbour. This paper will report on the various statistical models and methods that have been investigated for development of spatially and temporally detailed forecasts of surface winds in Sydney Harbour. An important part of the research has been concerned with characterising and predicting sea breeze occurrence, onset time, duration and strength.

Two basic approaches have been investigated. In the first, sea breeze and other important features of wind behaviour throughout the day are derived directly from the observed half hourly wind measurements. In the second, parsimonious parametric regression models that characterise the daily wind profiles have been developed. Methods for predicting the occurrence of sea breeze events include multiple logistic regression and classification and regression trees. Conditional on a sea breeze event being forecast the key features, such as onset time, duration and strength of winds, are forecast using multiple regression and multiple adaptive regression splines. Predictors used in these various models include those obtained from numerical prediction models and observed data prior to the forecast horizon.

Models for the spatial description of surface winds on the microscale of Sydney Harbour will also be described.