Data underlying the manuscript "Another look at asymmetry in the connection between ENSO and the NAO"

<b>This is the primary script, initial conditions, and boundary layer SST for an article going to be submitted to AMS JC, named “Another look at asymmetry in the connection between ENSO and the NAO”</b>. We conducted atmospheric modeling experiments using the European Center-Hamburg Model version 5.4 (ECHAM-5.4, Roeckner et al. 2003) from the Max-Plank Institute. The ECHAM5.4 was run with 1.875 lon*1.875lat horizontal spacing, 19 vertical levels from the surface to 10 hPa. In the control experiment (CTL), 1955-2009 monthly historical SST and SIC were used as the lower boundary condition and run for 55 years, including a 4-year spin-up. To reduce the potential impact of ENSO and NAO signals, 20 weak or neutral ENSO and NAO years (the normalized Niño-3.4 and NAO indices are between -0.7 and 0.7) were selected, including 1958, 1960, 1961, 1966, 1967, 1969, 1974, 1977, 1979, 1980, 1981, 1985, 1987, 1990, 1996, 2000, 2001, 2003, 2004, and 2006. To examine the influence of different types of ENSO on the NAO, we further performed nine sensitivity experiments covering only the period from December 1^st to February 28^th in the 20 sample years. The sensitivity-minus-CTL differences represent the atmospheric response to the SST anomalies in the different ENSO winters. The numerical result dataset is too large to archive, we provided the initial conditions for 20 sample years and the boundary layer conditions for the different sensitivity experiments. The folder contains the boundary layer condition for each sensitivity experiment is named after the experiment name. The initial conditions begin with "rerun".<br>

本数据集为投稿至美国气象学会《气候》期刊（American Meteorological Society Journal of Climate，简称AMS JC）的论文《再探ENSO与NAO关联的不对称性》的核心脚本、初始条件及边界层海表温度（Sea Surface Temperature, SST）资料。本研究采用马克斯·普朗克研究所（Max-Plank Institute）研发的欧洲汉堡模式5.4版本（ECHAM-5.4，Roeckner等，2003）开展大气数值模拟试验。该模式水平分辨率为1.875°经度×1.875°纬度，垂直方向共设19层，覆盖从地表至10百帕（hPa）的大气柱。控制试验（CTL）以1955-2009年逐月历史海表温度与海冰浓度（Sea Ice Concentration, SIC）作为下边界条件，连续积分55年，其中包含4年的模式自旋调整期（spin-up）。为弱化ENSO与NAO信号的潜在干扰，本研究筛选出20个ENSO与NAO均处于弱或中性状态的样本年份（标准化Niño-3.4指数与NAO指数均介于-0.7至0.7之间），具体年份包括1958、1960、1961、1966、1967、1969、1974、1977、1979、1980、1981、1985、1987、1990、1996、2000、2001、2003、2004及2006。为探究不同类型ENSO对NAO的影响，本研究进一步开展9组敏感性试验，试验时段限定为上述20个样本年份的12月1日至次年2月28日。敏感性试验与控制试验的差值（敏感性减CTL）即表征不同ENSO冬季海表温度异常对大气的强迫响应。由于数值模拟结果数据集体量庞大无法归档，本研究仅提供20个样本年份的初始条件，以及各组敏感性试验的边界层条件。存储单组敏感性试验边界层条件的文件夹以该试验名称命名；以“rerun”为前缀的文件即为初始条件文件。