Decadal prediction by using the CESM: A Case Study on the US 2014-2015 Winter Extreme Event

We first present analyses of the modes of variability of Sea Surface Temperature (SST) in the North Pacific and North Atlantic in the decadal prediction experiments with different lead time by the Community Earth System Model (CESM) and compare them with observations. Results show that the 1-year lead-forecast simulation captures the first three modes of in both Atlantic and Pacific in the observation. The 5-year, 9-year lead-forecast simulations capture the phase of the first mode in Atlantic Ocean, whereas only 5-year lead-forecast simulation captures the phase of the first mode in the Pacific Ocean. A case study of the 2014-2015 winter extreme events is used to evaluate the performance of the CESM prediction simulations with different lead time. We show predictionscan observed iesand in the Atlantic with significant lead time, These anomalies are shown to force atmospheric circulations that favor a cold winter in the eastern US and the drought in the western US relative to normal conditions.