Recent Challenges in the APCC Multi-Model Ensemble Seasonal Prediction:
Hindcast Period Issue
Abstract
Seasonal forecasts are commonly issued in the form of anomalies as
departures from average in a specified multiyear reference period
(climatology). The model climatology is estimated as average of
retrospective forecasts over the hindcast period. However, different
operational centers providing seasonal ensemble predictions use
different hindcast periods based on their own model climatology. In
addition, the hindcast period of recently developed/upgraded newer
models tends to shift to the recent years. In this paper, we discuss
recent challenges faced by the APCC multi-model ensemble (MME)
operations, especially changes in the hindcast period for individual
models. Based on the results of various sensitivity experiments for the
MME prediction, we proposed to change the hindcast period that is the
most appropriate solution for the APCC operations. It makes the newly
developed models join the MME and increase the total number of
participating models, which facilitates the skill improvement of the MME
prediction.