The resolution sensitivity of the South Asian monsoon and Indo-Pacific in a global 0.35A° AGCM
The resolution sensitivity of the South Asian monsoon and Indo-Pacific in a global 0.35A° AGCM
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DOI：
10.1007/s00382-015-2614-1
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发表时间：
2016-02-01
期刊：
影响因子：
4.6
通讯作者：
Strachan, Jane
中科院分区：
文献类型：
--
作者：
Johnson, Stephanie J.;Levine, Richard C.;Strachan, Jane
南亚季风是季节循环最重要的表现形式之一。它直接影响到世界近三分之一的人口，并具有重大的全球影响力。使用27年的高分辨率大气环流模式（气象局统一模式）的积分，我们研究南亚季风降水和环流的变化时，水平分辨率从大约200-40公里的赤道（N96-N512，1.9A度-0.35A度）。该数据集的高分辨率、积分长度和集合大小使其成为迄今为止用于评估南亚季风分辨率敏感性的最广泛的数据集。我们发现一个一致的模式JJAS降水和环流的变化，分辨率增加，其中包括略有增加，在印度半岛的降水，印度和印度支那的地形雨带的变化，增加风速在索马里急流，增加降水的海洋大陆岛屿和减少降水的北方海洋大陆海域。为了诊断哪些分辨率相关的过程导致这些变化，我们将其与已发表的改变区域地形和海岸线的敏感性实验进行比较。我们的分析表明，提高分辨率的东非高地的结果，在改善代表性的索马里喷气机，并进一步表明，提高分辨率的地形在印度支那和海洋大陆的结果在海洋大陆岛屿的降水量增加的代价减少降水进一步北。我们还评估了分辨率的敏感性季风低压和低，这有助于更多的降水在印度东北部在更高的分辨率。我们的结论是，虽然在这些尺度上提高分辨率并不能解决GCM中存在的许多季风偏差，但它有一些小的有益影响。
The South Asian monsoon is one of the most significant manifestations of the seasonal cycle. It directly impacts nearly one third of the world's population and also has substantial global influence. Using 27-year integrations of a high-resolution atmospheric general circulation model (Met Office Unified Model), we study changes in South Asian monsoon precipitation and circulation when horizontal resolution is increased from approximately 200-40 km at the equator (N96-N512, 1.9A degrees-0.35A degrees). The high resolution, integration length and ensemble size of the dataset make this the most extensive dataset used to evaluate the resolution sensitivity of the South Asian monsoon to date. We find a consistent pattern of JJAS precipitation and circulation changes as resolution increases, which include a slight increase in precipitation over peninsular India, changes in Indian and Indochinese orographic rain bands, increasing wind speeds in the Somali Jet, increasing precipitation over the Maritime Continent islands and decreasing precipitation over the northern Maritime Continent seas. To diagnose which resolution-related processes cause these changes, we compare them to published sensitivity experiments that change regional orography and coastlines. Our analysis indicates that improved resolution of the East African Highlands results in the improved representation of the Somali Jet and further suggests that improved resolution of orography over Indochina and the Maritime Continent results in more precipitation over the Maritime Continent islands at the expense of reduced precipitation further north. We also evaluate the resolution sensitivity of monsoon depressions and lows, which contribute more precipitation over northeast India at higher resolution. We conclude that while increasing resolution at these scales does not solve the many monsoon biases that exist in GCMs, it has a number of small, beneficial impacts.