Synoptic climatology of extreme precipitation in alpine Australia
Synoptic climatology of extreme precipitation in alpine Australia
复制标题
DOI：
10.1002/joc.3970
复制
发表时间：
2015-02
期刊：
影响因子：
--
通讯作者：
S. Fiddes;A. Pezza;V. Barras
中科院分区：
文献类型：
--
作者：
S. Fiddes;A. Pezza;V. Barras
地形与西风气流的相互作用可显著增强澳大利亚东部的极端降水。这些极端事件可能造成严重的洪水、破坏和对人类活动的干扰，但在某些地区，它们也是水和雪的宝贵来源。在这项研究中，我们使用雨量计和降雪累积数据来研究澳大利亚高山地区极端雨雪与大尺度气候之间的关系。这些数据被划分为三个地理位置：山脉的西部，山脊线和山脉的东部，以便探索每个地区的降水性质。这些结果证实了先前文献中关于西坡（即嵌入低气压和切断低气压）的天气模式，并对山脉东侧极端降水的不同过程提供了新的见解，我们发现这些过程主要与与极地纬度相连的阻塞结构有关。有趣的是，我们的分析表明，在中纬度地区，La Niña模式伴随着经向海表温度（SST）梯度的增强，与西部和高海拔地区的极端事件有关，而东部地区的极端降水组合与海表温度模式有关，类似于澳大利亚地区与全球变暖相关的主要信号。我们推测，虽然西部和高纬度地区依赖于海温梯度，增强了西风急流，但东部的极端事件依赖于阻塞模式（异常东风），这至少部分响应了全球海温变暖，西风带分别向南移动。这些结果有助于解释为什么阿尔卑斯山西侧的降水比东侧观测到的总降水减少得更快。
Extreme precipitation over the eastern Australia can be significantly enhanced by topographic interaction with the westerly flow. These extreme events can cause severe flooding, damage and disruption to human activities, yet in some areas they are also an invaluable source of water and snow. In this study, we use rain gauge and snowfall accumulation data to investigate connections between extreme rain and snow in alpine Australia and the large‐scale climate. These data have been divided into three geographical locations: the west of the mountains, the ridgeline and the east of the mountains in order to explore the nature of precipitation in each region. The results confirm previous synoptic patterns found earlier in the literature for the western slopes (namely embedded and cutoff lows), and add new insights into the different processes conducive to extreme precipitation on the eastern side of the ranges, which we find to be mostly associated with a blocking structure connected to polar latitudes. Interestingly, our analyses suggests that while a La Niña pattern accompanied by enhanced meridional sea surface temperature (SST) gradients over mid‐latitudes is associated with extreme events in the western and high regions, the extreme precipitation composites for the eastern region are associated with a SST pattern that resembles the predominant signal associated with global warming in the Australian region. We hypothesize that while the western and high regions rely on SST gradients, which enhance the westerly jet, the extreme events over the eastern side rely on blocking patterns (anomalous easterlies), which are at least partially responding to the global SST warming with the respective shift of the westerlies to the south. These results help explain why the precipitation over the western side of the Alps is declining more rapidly than the total precipitation observed on the eastern side.