Using the Schaake shuffle when calibrating ensemble means can be problematic
DL Shrestha, DE Robertson, JC Bennett, QJ Wang
Journal of Hydrology | Elsevier | Published : 2020
The Schaake shuffle is a simple and effective method for re-ordering calibrated ensemble forecasts. It is widely used in forecast calibration methods where realistic spatial and temporal sequences are important. We illustrate a previously unidentified problem with the application of the Schaake shuffle. When the autocorrelation of uncalibrated forecasts is markedly different from observations, the Schaake shuffle cannot guarantee that the calibrated ensemble is reliable when ensemble members are accumulated through time. Accumulations in time and space are particularly important for applications that integrate rainfall over these dimensions, notably hydrological modelling. We demonstrate tha..View full abstract
This research has been supported by the Water Information Research and Development Alliance (WIRADA) between the Bureau of Meteorology and CSIRO Land & Water. We would like to thank Dr. Seline Ng (CSIRO) for valuable suggestions on an earlier draft and two anonymous referees for their helpful and constructive comments.