Climate models have substantial biases in the climatological latitude of the Southern Hemisphere eddy‐driven jet and the time scale of annular mode variability and disagree on the jet response to climate change. Zonally symmetric dry dynamical cores are often used for idealized modeling of the jet response to forcing and its sensitivity to model setup changes. The limits to which these models represent the key mechanisms that control the jet in complex models or the real world have not been systematically investigated. Here we show that substantial intermodel differences in jet latitude and strength can arise from differences in dynamical cores and resolved topography. Including topography and a more realistic surface drag in a dry model substantially alters the jet response to changes in drag strength. Using real‐world maps, enhanced drag over land shifts the jet poleward, whereas enhanced drag over the ocean leads to an equatorward shift. No universal relationship between annular mode time scale and forced response emerges in the dry model with topography. These results suggest that zonally symmetric models with Rayleigh drag lack important mechanisms that control the behavior of the midlatitude jet in coupled climate models. A dry model with topography and quadratic surface drag can fill this gap in the model hierarchy.

中文翻译：

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地形和现实阻力对南半球中纬度干模型的影响

气候模式在南半球涡动射流的气候纬度和环形模式可变性的时间尺度上存在重大偏差，并且对射流对气候变化的响应持不同意见。区域对称干动力核心通常用于理想化的射流对强迫响应及其对模型设置变化的敏感性的建模。这些模型代表在复杂模型或现实世界中控制射流的关键机制的局限性尚未得到系统地研究。在这里，我们显示出动力纬度和已解决的地形差异可能导致射流纬度和强度之间存在明显的模型间差异。在干燥模型中包括地形和更逼真的表面阻力，会大大改变射流对阻力强度变化的响应。使用真实世界的地图，陆地上增加的阻力使射流向极移，而海洋上的增加的阻力导致赤道向移。在具有地形的干模型中，环形模式时标和强制响应之间没有普遍关系。这些结果表明，具有瑞利阻力的区域对称模型缺乏在耦合气候模型中控制中纬度射流行为的重要机制。具有地形和二次表面阻力的干模型可以填补模型层次结构中的空白。这些结果表明，具有瑞利阻力的区域对称模型缺乏在耦合气候模型中控制中纬度射流行为的重要机制。具有地形和二次表面阻力的干模型可以填补模型层次结构中的空白。这些结果表明，具有瑞利阻力的区域对称模型缺乏在耦合气候模型中控制中纬度射流行为的重要机制。具有地形和二次表面阻力的干模型可以填补模型层次结构中的空白。