Objective identification of wind change timing from single station observations. Part 2: towards the concept of a wind change climatolog

Fuzzy logic functions of time series ofMETAR and SPECI data were used in a companion paper to identify ‘timing’ of frontal wind changes on days that the Victorian Regional Forecast Centre of the Australian Bureau of Meteorology had issued a ‘Wind Change Forecast’, and the results compared with subjective wind change timings for these same events. In this paper the same algorithms are applied to the full METAR and SPECI database, and additional measures designed to quantify the ‘strength’ or ‘significance’ of the changes so identified are developed. It is shown that the algorithms identify many more changes than simply those that occur on the VRFC wind change days, and that the number of wind changes resolved varies with different screening thresholds, thus generating a wind change climatology at each observation site. Examples of potentially useful wind change climatology products are presented, and it is shown how the objective methods can identify significant change types other than those associated with strong, dry cold fronts.