Topographic Trapping of the Leeuwin Current and Its Impact on the 2010-2011 Ningaloo Niño
Topographic Trapping of the Leeuwin Current and Its Impact on the 2010-2011 Ningaloo Niño
复制标题
露文洋流的地形捕获及其对2010-2011年宁加洛尼诺现象的影响
作者：
Xue Feng;T. Shinoda;W. Han
此前的理论研究表明，澳大利亚西海岸的地形对于加强和捕获沿岸的露纹洋流（LC）起着重要作用。为了分离和量化大陆架和大陆坡对LC和宁加洛尼诺现象的影响，进行了不同底部地形的高分辨率（1/12°）海洋环流模型实验。 “对照”实验使用澳大利亚西海岸的真实底部地形，而敏感性（“无大陆架”）实验使用修改后的地形，在海岸附近没有大陆架和斜坡。 LC 的平均值和变异性在对照实验中得到真实模拟。与对照实验相比，无架实验中LC的强度下降了约28%。大陆架通过调节LC变率影响2010-2011年宁加洛尼诺现象的发展：2010年8月-10月和2011年1-2月，对照实验中的LC比无大陆架实验中的LC增强幅度更大。结果，2010年9月至2011年3月，对照实验中的上层50 m海洋比无陆架实验温暖了约26%。两个实验也发现了不同的海温变暖演化。两个实验中海洋过程的比较表明，对照实验中陆架斜坡地形可以有效捕获海岸的正海平面异常，而无陆架实验中从海岸辐射出更多的罗斯贝波，导致LC较弱。
Previous theoretical studies suggest that the topography along the west coast of Australia plays an important role in strengthening and trapping the Leeuwin Current (LC) at the coast. To isolate and quantify the effect of the continental shelf and slope on the LC and Ningaloo Niño, high-resolution (1/12°) ocean general circulation model experiments with different bottom topographies are performed. The “control” experiment uses a realistic bottom topography along the west coast of Australia, whereas the sensitivity (“no-shelf”) experiment uses a modified topography with no continental shelf and slope near the coast. The mean and variability of LC are realistically simulated in the control experiment. Compared to the control experiment, the strength of LC in the no-shelf experiment decreased by about 28%. The continental shelf influences the development of the 2010-2011 Ningaloo Niño through modulating the LC variability: in August-October 2010 and January-February 2011, the LC in the control experiment is enhanced much more than that in the no-shelf experiment. As a result, the upper 50 m ocean in the control experiment is about 26% warmer than the no-shelf experiment from september 2010 to March 2011. Different evolution of SST warming is also found in the two experiments. Comparisons of oceanic processes in the two experiments show that the shelf-slope topography can effectively trap the positive sea level anomaly at the coast in the control experiment while more Rossby waves radiate from the coast in the no-shelf experiment, resulting in a weaker LC.