Calibration and Uncertainty Quantification of a Gravity Wave Parameterization: A Case Study of the Quasi‐Biennial Oscillation in an Intermediate Complexity Climate Model
Calibration and Uncertainty Quantification of a Gravity Wave Parameterization: A Case Study of the Quasi‐Biennial Oscillation in an Intermediate Complexity Climate Model
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DOI：
10.1029/2022ms003245
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发表时间：
2022-10
影响因子：
6.8
通讯作者：
L. Mansfield;A. Sheshadri
中科院分区：
文献类型：
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作者：
L. Mansfield;A. Sheshadri
破碎大气重力波的拖曳力对中层大气环流的驱动起着主导作用，但由于其水平波长范围从几十公里到几千公里，在气候模式中必须对部分谱进行参数化。重力波参数化规定了低层大气中的波源谱，并允许这些波向上传播，直到它们消散或破裂，在那里它们存款拖曳大尺度流动。这些参数化是气候建模中不确定性的来源，而不确定性通常无法量化。在这里，我们使用校准，仿真和样本（CES）方法，在中等复杂性的全球气候模式中，假设参数化结构，探索与非地形重力波参数化相关的不确定性。我们首先校准定义热带重力波源谱的不确定参数，以获得与热带平流层变化的主要模式（准两年振荡（QBO））的特性一致的气候模式设置。然后，我们使用高斯过程仿真器对校准后的参数分布进行采样，并量化这些参数选择的不确定性。我们发现，由此产生的QBO周期和振幅的参数不确定性是一个类似的幅度的内部变化下的2xCO2强迫。
The drag due to breaking atmospheric gravity waves plays a leading order role in driving the middle atmosphere circulation, but as their horizontal wavelength range from tens to thousands of kilometers, part of their spectrum must be parameterized in climate models. Gravity wave parameterizations prescribe a source spectrum of waves in the lower atmosphere and allow these to propagate upwards until they either dissipate or break, where they deposit drag on the large‐scale flow. These parameterizations are a source of uncertainty in climate modeling which is generally not quantified. Here, we explore the uncertainty associated with a non‐orographic gravity wave parameterization given an assumed parameterization structure within a global climate model of intermediate complexity, using the Calibrate, Emulate and Sample (CES) method. We first calibrate the uncertain parameters that define the gravity wave source spectrum in the tropics, to obtain climate model settings that are consistent with properties of the primary mode of tropical stratospheric variability, the Quasi‐Biennial Oscillation (QBO). Then we use a Gaussian process emulator to sample the calibrated distribution of parameters and quantify the uncertainty of these parameter choices. We find that the resulting parametric uncertainties on the QBO period and amplitude are of a similar magnitude to the internal variability under a 2xCO2 forcing.