Subseasonal Forecast Skill for Weekly Mean Atmospheric Variability Over the Northern Hemisphere in Winter and Its Relationship to Midlatitude Teleconnections
Subseasonal Forecast Skill for Weekly Mean Atmospheric Variability Over the Northern Hemisphere in Winter and Its Relationship to Midlatitude Teleconnections
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DOI：
10.1029/2020gl088508
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发表时间：
2020-05
影响因子：
5.2
通讯作者：
A. Yamagami;M. Matsueda
中科院分区：
文献类型：
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作者：
A. Yamagami;M. Matsueda
本文分析了冬季北方半球500 hPa周平均高度距平的亚季节可预报性及其与遥相关的关系。北太平洋，加拿大和格陵兰岛的技能高于其他地区的第3周和第4周预测。这些峰值对应于太平洋-北美（PNA）型和北大西洋涛动（NAO）的作用中心。PNA（NAO阶段）预测厄尔尼诺年的提前时间为3-4周（2-4周）。与厄尔尼诺强迫相比，拉尼娜强迫对PNA和NAO预报的影响很小。数值模式在拉尼娜年的这些提前期有负的PNA偏差。结果表明，中纬度高空急流的改善，而不是热带地区对厄尔尼诺-南方涛动强迫的响应，可能会导致更好的S2 S预测。
This study assesses the subseasonal predictability of the weekly mean geopotential height anomaly at 500 hPa and its relationship to teleconnections over the Northern Hemisphere in winter. The skill over the North Pacific, Canada, and Greenland is higher than over other areas for weeks 3 and 4 forecasts. These peaks correspond to the centers of action for the Pacific–North American (PNA) pattern and the North Atlantic Oscillation (NAO). PNA (NAO phase) predictions are better for El Niño years at lead times of 3–4 weeks (2–4 weeks). The effects of La Niña forcing on PNA and NAO forecasts are small compared with the El Niño forcing. Numerical models have a negative PNA bias at these lead times in La Niña years. Results suggest that the improvement in the midlatitude upper‐level jet rather than in the response to El Niño–Southern Oscillation forcing in the tropics could lead to better S2S predictions.