Atmospheric blocking and upper-level Rossby-wave forecast skill dependence on model configuration
Atmospheric blocking and upper-level Rossby-wave forecast skill dependence on model configuration
复制标题
大气阻塞和高空罗斯贝波预报技能对模型配置的依赖
DOI：
10.1002/qj.3326
复制
发表时间：
2018
影响因子：
8.9
通讯作者：
Martínez-Alvarado O
中科院分区：
文献类型：
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作者：
Martínez-Alvarado O
天气模式在中期预报大气阻塞和高层Rossby波相关结构的能力上有所不同。在这里，我们评估模型的动态核心对这种预测的影响。使用欧洲中期天气预报中心（ECMWF）、气象局（MO）和韩国气象局（KMA）的集合预报系统（EPS）的业务预报。北方模式的输出是从冬季之前和之后的主要升级到动力核心的MO-EPS（称为MOGREPS）进行分析。KMA-EPS作为一个控制，因为它使用与MOGREPS相同的模型，但始终使用较旧的动态核心。MOGREPS和KMA-EPS之间分辨率差异的混杂因素使用MO预测模型后报实验进行评估，该实验使用较新的动力核心，但使用KMA-EPS的操作分辨率。MOGREPS中新的动力核心的引入导致了预测阻塞频率的增加，提前时间为5天和7天，抵消了通常观察到的阻塞频率随提前时间的减少。阻断活动、起始和衰减的命中率在主要阻断区域中也增加（假阳性率没有相应增加）。先前发现的上层脊面积和对流层顶锐度（通过等熵位涡梯度测量）随提前时间的减少也随着新的动力核心而减少。因此，这种动力核心的改进（与隐式阻尼的减少有关）被证明至少与业务分辨率的改进一样有效，可以改善高层Rossby波和相关阻塞的预报。
Weather models differ in their ability to forecast, at medium range, atmospheric blocking and the associated structure of upper‐level Rossby waves. Here, we evaluate the effect of a model's dynamical core on such forecasts. Operational forecasts from the ensemble prediction systems (EPSs) of the European Centre for Medium‐Range Weather Forecasts (ECMWF), the Met Office (MO) and the Korean Meteorological Administration (KMA) are used. Northern Hemisphere model output is analysed from the winters before and after a major upgrade to the dynamical core of the MO‐EPS (called MOGREPS). The KMA‐EPS acts as a control as it uses the same model as MOGREPS, but uses the older dynamical core throughout. The confounding factor of resolution differences between MOGREPS and the KMA‐EPS is assessed using a MO forecast model hindcast experiment with the more recent dynamical core, but with the operational resolution of the KMA‐EPS. The introduction of the new dynamical core in MOGREPS has led to increased forecast blocking frequency, at lead times of 5 and 7 days, counteracting the typically observed reduction in blocking frequency with lead time. Hit rates of blocking activity, onset and decay are also increased in the main blocking regions (without a corresponding increase in the false positive rate). The previously found reduction of the upper‐level ridge area and tropopause sharpness (measured by an isentropic potential vorticity gradient) with lead time is also reduced with the new dynamical core. This dynamical core improvement (associated with a reduction in implicit damping) is thus demonstrated to be at least as effective as operational resolution improvements in improving the forecasts of upper‐level Rossby waves and associated blocking.