Intraseasonal variability of the Indian summer monsoon: wet and dry events in COSMO-CLM
Intraseasonal variability of the Indian summer monsoon: wet and dry events in COSMO-CLM
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印度夏季风的季节内变化：COSMO-CLM 中的干湿事件
DOI：
10.1007/s00382-016-2989-7
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发表时间：
2016
期刊：
影响因子：
4.6
通讯作者：
U. Cubasch
中科院分区：
文献类型：
--
作者：
Befort;G.C. Leckebusch;U. Cubasch
本研究旨在验证由空间分辨率为55公里的ERA中期再分析数据驱动的广泛使用的区域气候模式COSMO-CLM，该模式与1979年至2011年期间印度夏季风(ISM)的季节内变化观测特征有关。这些特征之一是ISM的季节内振荡向北传播。我们发现，模型和观测之间的时间演化是很一致的，但在强度方面的一致性较差。此外，使用标准化降水指数研究了该模式在每周时间尺度上模拟观测的干湿事件的能力。总的来说，该模型能够同时模拟这些震级相近的事件。基于观测的分析表明，该模式很好地反映了印度地区大气环流异常和降水异常在季节内时间尺度上的耦合关系。干事件最重要的环流异常是印度上空的低对流层反气旋性涡旋，巴基斯坦地区部分是对流层上层的气旋性涡旋，湿事件的环流异常则相反。模型显示，与湿事件相比，模型模拟干旱事件的能力略高。总体而言，这项研究表明，目前的COSMO-CLM构型能够模拟印度夏季风的季节内变化的关键特征。认识到其局限性，COSMO-CLM适合于研究过去或未来气候条件变化下ISM的季节内变率的可能变化。
This study aims to validate the widely used regional climate model COSMO-CLM driven by ERA-Interim reanalysis data with a spatial resolution of 55 km with respect to observed features of the intraseasonal variability of the Indian summer monsoon (ISM) during the period 1979 until 2011. One of these features is the northward propagation of the ISM intraseasonal oscillations. We find, that the temporal evolution between model and observation is in good agreement, while less agreement with respect to the strength is found. Furthermore, the model’s capability to simulate observed dry and wet events on a weekly time-scale is investigated using the standardized precipitation index. In general, the model is capable to simulate these events with a similar magnitude at the same time. Observational based analyses show, that the coupling between atmospheric circulation anomalies and rainfall anomalies over India on the intraseasonal time scale is well represented by the model. The most important circulation anomalies for dry events are a lower tropospheric anti-cyclonic vortex over India and partly an upper tropospheric cyclonic vortex over the Pakistan region and vice versa for wet events. The model shows a slightly higher ability to simulate dry compared to wet events. Overall, this study shows that the current configuration of COSMO-CLM is able to simulate the key features of the intraseasonal variability of the Indian summer monsoon. Being aware of its limitation, COSMO-CLM is suitable to investigate possible changes of the intraseasonal variability of ISM under changed climate conditions in the past or in the future.
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影响因子：
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作者：
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DOI：
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发表时间：
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期刊：
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作者：
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DOI：
--
发表时间：
2009
期刊：
影响因子：
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作者：
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通讯作者：
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