453: Exceedance Probabilities

The exceedance probabilities indicate the probability that the value on the x -axis will be exceeded. The exceedance probabilities are calculated using the climatological data (see Climatology for details on setting the climatological period) and are shown by the thick red line, as well as by a smoothed thin red line that represents a normal distribution fit to the data. (If the Transform Y Data option is switched on the fitted distribution will not be smooth, but it will not be stepped either). The probabilities indicated by the green curve are calculated using the current forecast. The values on the x -axis can be shown as anomalies, standardised anomalies of % of average (if the Zero Bound option is switched on) by selecting the appropriate standardisation option from the Customise menu item. The shading and vertical dashed lines show the thresholds for the "above" and below" categories.

If more than one forecast is produced, the forecasts can be cycled using the up and down arrows (which will work better than attempting to type in the year, although CPT occasionally loses track of the year if they are cycled through too quickly). Similarly, the curves for different gridpoints / stations / series can be viewed by setting the appropriate number at the prompt. A series that has been omitted in the calculations will be skipped.

The forecasts can be saved by selecting the Forecasts tab from the File _Output Results ) menu. The graph itself can be exported as a graphics file by right-clicking anywhere in the child window and selecting Export from the pop-up menu. A default name is given to the graphics file, but this name can be changed using the browse button. The image quality for all the graphics formats can be improved by increasing the size of the image (see Options ~ Graphics ~ Graph Scaling ). The graphic title can be set using the Customise option upon right-clicking in the child window.

The y-axis limits can be set by right-clicking on the image and then selecting the Customise ~ Y-Axis Limits option. The maximum and minimum values on the y-axis are indicated and can be reset. Resetting these axis limits will in turn automatically reset the tick-mark interval and number of tick marks. Greater flexibility for setting the tick marks is planned for future releases. Further options for customising the graph, including adjusting the size of the fonts, and the size of the images, are available from Options ~ Graphics .