Downscaling of South America present climate driven by 4-member HadCM3 runs
Downscaling of South America present climate driven by 4-member HadCM3 runs
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DOI：
10.1007/s00382-011-1002-8
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发表时间：
2012-02-01
期刊：
影响因子：
4.6
通讯作者：
Tavares, Priscila
中科院分区：
文献类型：
--
作者：
Chou, Sin Chan;Marengo, Jose A.;Tavares, Priscila
这项工作的目标是使用由英国气象局哈德利中心 HadCM3 全球模型的四名成员驱动的区域 Eta 模型来评估南美洲的气候模拟。为了进行长期的年代际整合，Eta 模型已被修改，并已显示出在 HadCM3 的强制下可以很好地再现 1961-1990 年期间的“当前气候”aEuro”。以 6 小时的频率提供分辨率为 2.5A 纬度 x 3.75A 经度的全球模型横向条件。全球模型集合的每个成员都有不同的气候敏感性，并且选择四个成员来跨越HadCM3 全球模型中嵌套的 Eta 模型配置为 40 公里水平分辨率和 38 层垂直方向，显示了 1961-90 年南方夏季和冬季气候的结果，该结果与再分析数据以及平均降水量和温度非常吻合。与模型误差相比，降尺度平均降水量和温度的分布较小，在 HadCM3 成员运行中，根据所研究的厄尔尼诺现象和拉尼娅事件的频率，确定了集合平均值对任何一个年份的季节周期的改进。 HadCM3 低估了这些事件的典型降水和温度异常，尽管异常位置发生了小幅位移，但该实验配置是实施 Eta-CPTEC/HadCM3 即将进行的气候变化研究实验的第一步。
The objective of this work is to evaluate climate simulations over South America using the regional Eta Model driven by four members of an ensemble of the UK Met Office Hadley Centre HadCM3 global model. The Eta Model has been modified with the purpose of performing long-term decadal integrations and has shown to reproduce "present climate"aEuro"the period 1961-1990-reasonably well when forced by HadCM3. The global model lateral conditions with a resolution of 2.5A degrees latitude x 3.75A degrees longitude were provided at a frequency of 6 h. Each member of the global model ensemble has a different climate sensitivity, and the four members were selected to span the range of uncertainty encompassed by the ensemble. The Eta Model nested in the HadCM3 global model was configured with 40-km horizontal resolution and 38 layers in the vertical. No large-scale internal nudging was applied. Results are shown for austral summer and winter at present climate defined as 1961-90. The upper and low-level circulation patterns produced by the Eta-CPTEC/HadCM3 experiment set-up show good agreement with reanalysis data and the mean precipitation and temperature with CRU observation data. The spread in the downscaled mean precipitation and temperature is small when compared against model errors. On the other hand, the benefits in using an ensemble is clear in the improved representation of the seasonal cycle by the ensemble mean over any one realization. El Nio and La Nia years were identified in the HadCM3 member runs based on the NOAA Climate Prediction Center criterion of sea surface temperature anomalies in the Nio 3.4 area. The frequency of the El Nio and La Nia events in the studied period is underestimated by HadCM3. The precipitation and temperature anomalies typical of these events are reproduced by most of the Eta-CPTEC/HadCM3 ensemble, although small displacements of the positions of the anomalies occur. This experiment configuration is the first step on the implementation of Eta-CPTEC/HadCM3 upcoming experiments on climate change studies that are discussed in a companion paper.