Seasonal Predictability of the North Atlantic Oscillation and Zonal Mean Fields Associated with Stratospheric Influence in JMA/MRI-CPS2
Seasonal Predictability of the North Atlantic Oscillation and Zonal Mean Fields Associated with Stratospheric Influence in JMA/MRI-CPS2
复制标题
DOI：
10.2151/sola.2017-038
复制
发表时间：
2017
期刊：
影响因子：
1.9
通讯作者：
Naoaki Saito;S. Maeda;T. Nakaegawa;Y. Takaya;Y. Imada;Chihiro Matsukawa
中科院分区：
文献类型：
--
作者：
Naoaki Saito;S. Maeda;T. Nakaegawa;Y. Takaya;Y. Imada;Chihiro Matsukawa
北大西洋涛动（NAO）是影响冬季气候的最主要的半球变率。然而，很难在季节时间尺度上预测NAO。因此，更好地了解NAO对提高季节预报的准确性非常重要。我们调查的季节可预报性NAO和纬向平均场的平流层使用后报的业务季节预报系统的基础上，日本气象厅。我们发现，无论是预测技能和潜在的可预测性NAO指数增加，从冬末到早春，这种季节性与高的可预测性的纬向平均位势高度在平流层和近地面。对Eliassen-Palm通量辐合/辐散的分析表明，平流层在冬末的高可预报性是由向上传播的Rossby波的大信号引起的。还利用Ambaum和霍斯金斯（2002）提出的方法定量估计了从平流层到对流层的可预测信号的向下影响。由平流层位涡估计的地面气压信号与实际信号基本一致，证实了平流层对近地面季节可预报性的贡献。（引用：Saito，N.，S.前田，T。Nakaegawa，Y. Takaya，Y. Imada和C.松川，2017年：在JMA/MRI-CPS 2中与平流层影响有关的北大西洋振荡和纬向平均场的季节可预报性。SOLA，13，209−213，doi：10.2151/sola.2017-038.）
The North Atlantic Oscillation (NAO) is the most dominant hemispheric variability affecting the winter climate. It is, however, difficult to predict the NAO on a seasonal time scale. Thus, a better understanding of the NAO is important for improving the accuracy of seasonal forecasts. We investigated the seasonal predictability of the NAO and the zonal mean fields of the stratosphere using hindcasts based on the operational seasonal prediction system of the Japan Meteorological Agency. We found that both the predictive skill and the potential predictability of the NAO index increased from late winter to early spring and that this seasonality relates to high predictability of the zonal mean geopotential height in the stratosphere and near the surface. Analysis of the convergence/divergence of the Eliassen–Palm flux indicates that the high predictability in the stratosphere in late winter results from the large signal of upward-propagating Rossby waves. The downward influence of the predictable signal from the stratosphere to the troposphere was also quantitatively estimated using the approach proposed by Ambaum and Hoskins (2002). The signal of the surface pressure estimated from that of stratospheric potential vorticity is roughly consistent with the actual signal, substantiating the stratospheric contribution to the near-surface seasonal predictability. (Citation: Saito, N., S. Maeda, T. Nakaegawa, Y. Takaya, Y. Imada, and C. Matsukawa, 2017: Seasonal predictability of the North Atlantic Oscillation and zonal mean fields associated with stratospheric influence in JMA/MRI-CPS2. SOLA, 13, 209−213, doi:10.2151/sola.2017-038.)