The resolution sensitivity of the Asian summer monsoon and its inter-model comparison between MRI-AGCM and MetUM
The resolution sensitivity of the Asian summer monsoon and its inter-model comparison between MRI-AGCM and MetUM
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DOI：
10.1007/s00382-016-3517-5
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发表时间：
2017-01
期刊：
影响因子：
4.6
通讯作者：
T. Ogata;Stephanie J. Johnson;R. Schiemann;M. Demory;R. Mizuta;K. Yoshida;Osamu Arakawa
中科院分区：
文献类型：
--
作者：
T. Ogata;Stephanie J. Johnson;R. Schiemann;M. Demory;R. Mizuta;K. Yoshida;Osamu Arakawa
在本研究中，我们比较了两种大气环流模式（AGCMs）： MRI-AGCM和MetUM对亚洲夏季风（ASM）的分辨率敏感性。我们分析了三种不同分辨率的MetUM， N96（赤道约200公里网格）、N216（90公里网格）和N512（40公里网格），以及TL95（赤道约180公里网格）、TL319（60公里网格）和TL959（20公里网格）的MRI-AGCM。MRI-AGCM和MetUM都显示西太平洋降水随分辨率的增加而减少，但它们在印度洋的降水响应不同。在MRI-AGCM中，赤道附近（5-20°N）出现了较大的降水增加。在MetUM，这种赤道外降水的增加不太显著，赤道上的降水减少。水汽收支分析表明，高分辨率水汽通量辐合的变化与降水响应有关。探讨了地形效应、季节内变率和经向热梯度的表现作为分辨率敏感性的可能原因。高分辨率的agcm （TL959和N512）都可以代表陡峭的地形，这锚定了南亚和海洋大陆的降雨模式。在MRI-AGCM中，TL959低压系统的表现也对降水模式有贡献。此外，经向热梯度的季节演变在高分辨率下更为准确，特别是在MRI-AGCM中。这些发现强调了分辨率的影响仅在两种agcm中对ASM的某些特征具有鲁棒性，并强调了多模式研究GCM分辨率灵敏度的重要性。
In this study, we compare the resolution sensitivity of the Asian Summer Monsoon (ASM) in two Atmospheric General Circulation Models (AGCMs): the MRI-AGCM and the MetUM. We analyze the MetUM at three different resolutions, N96 (approximately 200-km mesh on the equator), N216 (90-km mesh) and N512 (40-km mesh), and the MRI-AGCM at TL95 (approximately 180-km mesh on the equator), TL319 (60-km mesh), and TL959 (20-km mesh). The MRI-AGCM and the MetUM both show decreasing precipitation over the western Pacific with increasing resolution, but their precipitation responses differ over the Indian Ocean. In MRI-AGCM, a large precipitation increase appears off the equator (5–20°N). In MetUM, this off-equatorial precipitation increase is less significant and precipitation decreases over the equator. Moisture budget analysis demonstrates that a changing in moisture flux convergence at higher resolution is related to the precipitation response. Orographic effects, intra-seasonal variability and the representation of the meridional thermal gradient are explored as possible causes of the resolution sensitivity. Both high-resolution AGCMs (TL959 and N512) can represent steep topography, which anchors the rainfall pattern over south Asia and the Maritime Continent. In MRI-AGCM, representation of low pressure systems in TL959 also contributes to the rainfall pattern. Furthermore, the seasonal evolution of the meridional thermal gradient appears to be more accurate at higher resolution, particularly in the MRI-AGCM. These findings emphasize that the impact of resolution is only robust across the two AGCMs for some features of the ASM, and highlights the importance of multi-model studies of GCM resolution sensitivity.