An objective tropical Atlantic sea surface temperature gradient index for studies of south Amazon dry-season climate variability and change.
An objective tropical Atlantic sea surface temperature gradient index for studies of south Amazon dry-season climate variability and change.
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DOI：
10.1098/rstb.2007.0024
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发表时间：
2008-05-27
期刊：
影响因子：
--
通讯作者：
Moufouma-Okia W
中科院分区：
文献类型：
--
作者：
Good P;Lowe JA;Collins M;Moufouma-Okia W
未来热带大西洋纬向海表温度（SST）梯度的变化可能会影响亚马逊旱季降水的水分辐合和垂直运动的模式的转变。与厄尔尼诺-南方涛动不同，没有量化这一梯度的标准指数。在这里，我们描述了一种方法，用于确定SST梯度，是最密切相关的6月至8月的降水在亚马逊河南部。我们使用的大气环流模式（AGCM）集成强迫观测SST从1949年到2005年的集合。大量的热带大西洋SST梯度指数随机生成，这些指数和6月至8月的平均降水在亚马逊盆地赤道以南的时间相关性进行了检查。与6月至8月亚马逊南部降水相关性最强的指数形成了一个以赤道附近为中心的近赤道方向的集群。梯度的南部分量的位置在巴西热带海岸外的一个区域特别明确，这与已知的物理机制是一致的。所选择的指数似乎捕捉到了大西洋SST对模拟亚马逊南部旱季降水的影响，并与观测到的亚马逊南部降水显着相关。我们在36个不同的大气-海洋耦合模式预测中研究了该指数，这些模式预测了在CO2简单复合增加1%的情况下气候变化。在广泛的响应中，我们发现了该指数的预测趋势与亚马逊旱季降水趋势之间的关系。此外，趋势关系的大小与AGCM模拟中发现的年际变率关系一致。这表明，该指数可用于量化该区域气候变化的不确定性。
Future changes in meridional sea surface temperature (SST) gradients in the tropical Atlantic could influence Amazon dry-season precipitation by shifting the patterns of moisture convergence and vertical motion. Unlike for the El Niño-Southern Oscillation, there are no standard indices for quantifying this gradient. Here we describe a method for identifying the SST gradient that is most closely associated with June–August precipitation over the south Amazon. We use an ensemble of atmospheric general circulation model (AGCM) integrations forced by observed SST from 1949 to 2005. A large number of tropical Atlantic SST gradient indices are generated randomly and temporal correlations are examined between these indices and June–August precipitation averaged over the Amazon Basin south of the equator. The indices correlating most strongly with June–August southern Amazon precipitation form a cluster of near-meridional orientation centred near the equator. The location of the southern component of the gradient is particularly well defined in a region off the Brazilian tropical coast, consistent with known physical mechanisms. The chosen index appears to capture much of the Atlantic SST influence on simulated southern Amazon dry-season precipitation, and is significantly correlated with observed southern Amazon precipitation. We examine the index in 36 different coupled atmosphere–ocean model projections of climate change under a simple compound 1% increase in CO2. Within the large spread of responses, we find a relationship between the projected trend in the index and the Amazon dry-season precipitation trends. Furthermore, the magnitude of the trend relationship is consistent with the inter-annual variability relationship found in the AGCM simulations. This suggests that the index would be of use in quantifying uncertainties in climate change in the region.
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影响因子：
5.2
作者：
Knight, Jeff R.;Folland, Chris K.;Scaife, Adam A.
通讯作者：
Scaife, Adam A.
影响因子：
5.2
作者：
Li, Wenhong;Dickinson, Robert E.;Canadell, Josep G.
通讯作者：
Canadell, Josep G.
DOI：
10.1002/qj.49712757512
发表时间：
2001-07-01
影响因子：
8.9
作者：
Rowell, DP
通讯作者：
Rowell, DP
DOI：
10.1098/rstb.2007.0037
发表时间：
2008-05-27
影响因子：
6.3
作者：
Harris, Phil P.;Huntingford, Chris;Cox, Peter M.
通讯作者：
Cox, Peter M.
影响因子：
4.6
作者：
Gordon, C;Cooper, C;Wood, RA
通讯作者：
Wood, RA