Two-Year Dynamical Predictions of ENSO Event Duration during 1954–2015
Two-Year Dynamical Predictions of ENSO Event Duration during 1954–2015
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DOI：
10.1175/jcli-d-20-0619.1
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发表时间：
2021-02
影响因子：
4.9
通讯作者：
Xiandu Wu;Y. Okumura;C. Deser;P. DiNezio
中科院分区：
文献类型：
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作者：
Xiandu Wu;Y. Okumura;C. Deser;P. DiNezio
厄尔尼诺和拉尼娜事件在历史记录中显示出广泛的持续时间。事件持续时间的可预测性在很大程度上仍然是未知的，尽管多年事件可能会延长其气候影响。为了探索厄尔尼诺和拉尼娜事件持续时间的可预测性，使用社区地球系统模式第1版（CESM 1）进行了多年集合预报。10-40成员预报是在1954-2015年期间每年3月1日、6月1日和11月1日观测到的海洋条件下初始化的;集合传播是通过对大气初始条件的轻微扰动而产生的。CESM 1预测个别厄尔尼诺和拉尼娜事件的持续时间，提前时间从6个月到25个月不等。特别是，在厄尔尼诺或拉尼娜现象第一个高峰附近的11月份初始化的预测可以巧妙地预测该事件是否会持续到第二年，提前1年。多年期拉尼娜现象的发生甚至可以更早地预测，提前时间可达25个月，特别是在发生强厄尔尼诺现象之前。事件持续时间的可预测性来自赤道太平洋的初始温跃层深度异常，以及热带太平洋内外的海面温度异常。另一方面，预报误差的增长主要来自北太平洋冬季的大气变率。事件持续时间的高度可预测性表明，有可能将厄尔尼诺和拉尼娜事件的12个月业务预报再延长一年。
El Niño and La Niña events show a wide range of durations over the historical record. The predictability of event duration has remained largely unknown, although multiyear events could prolong their climate impacts. To explore the predictability of El Niño and La Niña event duration, multiyear ensemble forecasts are conducted with the Community Earth System Model, version 1 (CESM1). The 10–40-member forecasts are initialized with observed oceanic conditions on 1 March, 1 June, and 1 November of each year during 1954–2015; ensemble spread is created through slight perturbations to the atmospheric initial conditions. The CESM1 predicts the duration of individual El Niño and La Niña events with lead times ranging from 6 to 25 months. In particular, forecasts initialized in November, near the first peak of El Niño or La Niña, can skillfully predict whether the event continues through the second year with 1-yr lead time. The occurrence of multiyear La Niña events can be predicted even earlier with lead times up to 25 months, especially when they are preceded by strong El Niño. The predictability of event duration arises from initial thermocline depth anomalies in the equatorial Pacific, as well as sea surface temperature anomalies within and outside the tropical Pacific. The forecast error growth, on the other hand, originates mainly from atmospheric variability over the North Pacific in boreal winter. The high predictability of event duration indicates the potential for extending 12-month operational forecasts of El Niño and La Niña events by one additional year.