Estimation of Weather Noise in Coupled Ocean-Atmosphere Systems Using Initialized Simulations
Estimation of Weather Noise in Coupled Ocean-Atmosphere Systems Using Initialized Simulations
复制标题
使用初始化模拟估计海洋-大气耦合系统中的天气噪声
DOI：
10.1175/jcli-d-15-0737.1
复制
发表时间：
2016
影响因子：
4.9
通讯作者：
Shukla Jagadish
中科院分区：
文献类型：
--
作者：
Zhu Jieshun;Shukla Jagadish
本研究提出一种新的方法来估计大气天气噪声的耦合模式，这是基于初始化的模拟与CGCM。在该方法中，通过去除信号部分来估计天气噪声，如从耦合系综平均模拟确定的。将耦合模型估计的天气噪声与非耦合AGCM模拟估计的天气噪声进行比较。本研究中使用的模型是CFSv 2。初始化模拟从1982-2009年期间的每年4月开始，与4名成员配对，并延长6个月。为了清楚地比较耦合和非耦合模拟中的天气噪声，进行了一组非耦合AGCM（CFSv 2的大气分量）模拟，这些模拟是由上述初始化CGCM模拟的日平均SST强迫的。比较表明，在亚洲-太平洋季风区，当地的海气耦合是重要的，噪声方差一般减少海气耦合的结果，是总方差和信号方差。这一结果与以前的研究结果相反，以前的研究表明，耦合和非耦合模型的噪声方差是相同的。它表明，以前的结论只是一个人工制品的假设中应用的AGCM为基础的方法（即，耦合和非耦合模拟之间的信号相同）。此外，方差差异也表现出明显的季节性，在季风区的差异较大，出现在北方夏季。另一组由相同SST强迫进行的AGCM实验表明，基于CGCM的方法在最初开始的2个月内通常仍然有效。
This study presents a new method to estimate atmospheric weather noise from coupled models, which is based on initialized simulations with a CGCM. In this method, the weather noise is estimated by removing the signal part, as determined from the coupled ensemble mean simulations. The weather noise estimated from coupled models is compared with that estimated from uncoupled AGCM simulations. The model used in this study is CFSv2. The initialized simulations start from each April during 1982–2009 paired with four members and extend for 6 months. To make a clear comparison between weather noise in coupled and uncoupled simulations, a set of uncoupled AGCM (the atmospheric component of CFSv2) simulations are conducted, which are forced by the daily mean SSTs from the above initialized CGCM simulations. The comparison indicates that, over the Asia–Pacific monsoon region where the local air–sea coupling is important, the noise variances are generally reduced as a result of air–sea coupling, as are the total and signal variances. This result stands in contrast to the results of previous studies that suggested that the noise variance for coupled and uncoupled models is the same. It is shown that the previous conclusion is simply an artifact of the assumption applied in the AGCM-based approach (i.e., the signal is the same between coupled and uncoupled simulations). In addition, the variance difference also exhibits a clear seasonality, with a larger difference over the monsoon region appearing toward boreal summer. Another set of AGCM experiments forced by the same SST suggests that the CGCM-based method generally remains valid in estimating weather noise within 2 months of its initial start.