Aquaplanet experiments are important tools for understanding and improving physical processes simulated by global models; yet, previous aquaplanet experiments largely differ in their representation of subseasonal tropical rainfall variability. This study presents results from aquaplanet experiments produced with the Model for Prediction Across Scales‐Atmosphere (MPAS‐A)—a community model specifically designed to study weather and climate in a common framework. The mean climate and tropical rainfall variability simulated by MPAS‐A with varying horizontal resolution were compared against results from a recent suite of aquaplanet experiments. This comparison shows that, regardless of horizontal resolution, MPAS‐A produces the expected mean climate of an aquaplanet framework with zonally symmetric but meridionally varying sea‐surface temperature. MPAS‐A, however, has a stronger signal of tropical rainfall variability driven by convectively coupled equatorial waves. Sensitivity experiments with different cumulus parameterizations, physics packages, and vertical grids consistently show the presence of those waves, especially equatorial Kelvin waves, in phase with lower‐tropospheric convergence. Other models do not capture such rainfall‐kinematics phasing. These results suggest that simulated tropical rainfall variability depends not only on the cumulus parameterization (as suggested by previous studies) but also on the coupling between physics and dynamics of climate and weather prediction models.

中文翻译：

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利用跨尺度大气预测模型进行水上行星模拟的平均气候和热带降雨变化

水上行星实验是了解和改善全球模型模拟的物理过程的重要工具；但是，先前的滑水行星实验在不同季节下对热带雨季变化的表示上存在很大差异。这项研究展示了使用跨尺度大气模型（MPAS-A）进行的滑水行星实验的结果，该模型是专门为在一个通用框架内研究天气和气候而设计的社区模型。将MPAS-A模拟的具有不同水平分辨率的平均气候和热带降雨变化与最近一组水上行星实验的结果进行了比较。这种比较表明，无论水平分辨率如何，MPAS‐A都会产生具有纬向对称但子午线变化的海表温度的滑水板框架的预期平均气候。然而，由对流耦合的赤道波驱动，MPAS-A具有更强的热带降雨变化信号。使用不同的累积参数化，物理程序包和垂直网格进行的敏感性实验始终显示出这些波的存在，尤其是赤道开尔文波，与低对流层会聚相一致。其他模型没有捕获这种降雨运动学相位。这些结果表明，模拟的热带降雨变化不仅取决于积云参数化（如先前的研究所建议），而且还取决于物理学与气候和天气预报模型动力学之间的耦合。物理软件包和垂直网格始终显示出这些波的存在，特别是赤道开尔文波，与低对流层会聚相一致。其他模型没有捕获这种降雨运动学相位。这些结果表明，模拟的热带降雨变化不仅取决于积云参数化（如先前的研究所建议），而且还取决于物理学与气候和天气预报模型动力学之间的耦合。物理数据包和垂直网格始终显示出这些波的存在，特别是赤道开尔文波，与低对流层会聚相一致。其他模型没有捕获这种降雨运动学相位。这些结果表明，模拟的热带降雨变化不仅取决于积云参数化（如先前的研究所建议），而且还取决于物理学与气候和天气预报模型动力学之间的耦合。