532: Climatological Period

The climatological period option allows you to specify the period used to calculate the terciles (or other thresholds) used for the forecasts. Forecast categories and probabilities will be calculated using the new climatological period. Cross-validated results are unaffected, although the new terciles will be shown on all graphs.

When there are multiple seasons (either because of seasonally sequenced forecast probabilities in the X file when running PFV, or if there are lagged fields in the Y-file) the precise climatological period is affected by the ordering of the seasons in the respective input file. The first year of the climatological period is applied to the first season in the file, and the last year of the climatological period will apply to the last season in the seasonal sequencing (which is not necessarily the last season in the file because the last year in the file may be incomplete). For example, if an X file contains forecast probabilities for two seasons, October-December (OND), and January-March (JFM), and the file starts with probabilities for OND, then the climatological period is set as 1971 - 2000, a 1971-1999 climatology will apply to OND, while a 1972-2000 climatology will apply to JFM. In this case if it is desired to have a 1971-2000 climatology for both seasons then the input file should be made to start with JFM, which could be set to missing values.

When entering years for a climatology with persisence, enter the first year for the persisted component of the season, not for the predicted component. For example if the persisted season is DJF, and the predicted season is MAM, and you want the climatology to startin (DJF)MAM 2000/2001, enter 2000.