Figure 13.2: Time series (a) of the number of weak (with central pressures not falling below 990 hPa) tropical cyclones in the Australian region (105-160 E) and (b) the number of moderate and intense (with central pressures less than or equal to 990 hPa). The two dashed lines in (a) show the 1969/70-1984/85 and 1985/86-1995/96 mean values of 2.4 and 1.1, respectively. The dotted line in (b) is the linear trend for the time series. The cyclone season starts around November and lasts until about May. The abscissa gives the year in which the cyclone season starts (e.g. the 1969/70 season is plotted against "1969") (adapted from Nicholls et al. 1998).