Dry spots and wet spots in the Andean hotspot
Dry spots and wet spots in the Andean hotspot
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DOI：
10.1111/j.1365-2699.2006.01682.x
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发表时间：
2007-08-01
影响因子：
3.9
通讯作者：
Mejia, John
中科院分区：
文献类型：
--
作者：
Killeen, Timothy J.;Douglas, Michael;Mejia, John
目的为了解释地形，盛行风和降水之间的关系，以确定区域对比降水制度，然后在气候变化的背景下比较区域之间的植物区系相似性。位置热带安第斯山脉，南美洲东部斜坡。方法我们使用的信息来源在公共领域，以确定地质，地形，盛行风模式和降水之间的关系。对比降水制度的地区进行了识别和比较，他们的植物区系similarity.Results我们确定空间分离的超湿润，潮湿和相对干燥的地区的东部斜坡的安第斯山脉，并显示它们是如何形成的盛行风，昼夜变化的大气环流和当地地形的相互作用的安第斯山脉。与这些气候不同地区的形成相关的一个关键方面是南美洲低空急流（SALLJ），这是一种相对稳定的风环流，它沿着安第斯山脉的东坡沿着向极地流动，是与跨越亚马逊盆地的大西洋信风相关的环流的一部分。最强的SALLJ风出现在“安第斯山脉的肘部”附近，位于南纬18度。年平均降水量大于3500毫米的超湿润地区与地形、气流方向和当地空气循环的“有利”组合有关，有利于在一天中的某些时间上升。更干燥的地区，平均年降水量小于1500毫米，与“不利”的地形方向相对于平均风和地区的减少云量产生的当地微风，温和的云量。我们显示了卫星估计的云量频率的分布，并提供假设来解释这些模式的发生，并解释在玻利维亚和北方秘鲁的降水量低的地区。区系分析表明，本研究的所有外切区域之间的总体相似性较低，但是，超湿润和湿润地区之间的相似性较大时，与干燥地区之间的相似性。空间上分离的地区与潮湿和超潮湿的降水制度表现出相似的梯度，与纬度（接近）和precipitation.Main结论降水的分布在东部斜坡的安第斯山脉不简单地与纬度相关，因为通常假设，但风和地形之间的相互作用的结果。了解造成观测到的降水模式的现象对于生物多样性绘图和建模以及解释过去和未来的气候情景和气候变化对生物多样性的影响都很重要。超湿润和干旱地区的地形特征有助于当地气候稳定，可能是生物多样性的祖先避难所;这些地区由于其独特的气候特征和与这些特征相关的生物多样性而成为保护的优先事项。
Aim To explain the relationship between topography, prevailing winds and precipitation in order to identify regions with contrasting precipitation regimes and then compare floristic similarity among regions in the context of climate change.Location Eastern slope of the tropical Andes, South America.Methods We used information sources in the public domain to identify the relationship between geology, topography, prevailing wind patterns and precipitation. Areas with contrasting precipitation regimes were identified and compared for their floristic similarity.Results We identify spatially separate super-humid, humid and relatively dry regions on the eastern slope of the Andes and show how they are formed by the interaction of prevailing winds, diurnally varying atmospheric circulations and the local topography of the Andes. One key aspect related to the formation of these climatically distinct regions is the South American low-level jet (SALLJ), a relatively steady wind gyre that flows pole-ward along the eastern slopes of the Andes and is part of the gyre associated with the Atlantic trade winds that cross the Amazon Basin. The strongest winds of the SALLJ occur near the 'elbow of the Andes' at 18 degrees S. Super-humid regions with mean annual precipitation greater than 3500 mm, are associated with a 'favourable' combination of topography, wind-flow orientation and local air circulation that favours ascent at certain hours of the day. Much drier regions, with mean annual precipitation less than 1500 mm, are associated with 'unfavourable' topographic orientation with respect to the mean winds and areas of reduced cloudiness produced by local breezes that moderate the cloudiness. We show the distribution of satellite-estimated frequency of cloudiness and offer hypotheses to explain the occurrence of these patterns and to explain regions of anomalously low precipitation in Bolivia and northern Peru. Floristic analysis shows that overall similarity among all circumscribed regions of this study is low; however, similarity among super-humid and humid regions is greater when compared with similarity among dry regions. Spatially separate areas with humid and super-humid precipitation regimes show similarity gradients that are correlated with latitude (proximity) and precipitation.Main conclusions The distribution of precipitation on the eastern slope of the Andes is not simply correlated with latitude, as is often assumed, but is the result of the interplay between wind and topography. Understanding the phenomena responsible for producing the observed precipitation patterns is important for mapping and modelling biodiversity, as well as for interpreting both past and future climate scenarios and the impact of climate change on biodiversity. Super-humid and dry regions have topographic characteristics that contribute to local climatic stability and may represent ancestral refugia for biodiversity; these regions are a conservation priority due to their unique climatic characteristics and the biodiversity associated with those characteristics.