Subantarctic cyclones identified by 14 tracking methods, and their role for moisture transports into the continent
Subantarctic cyclones identified by 14 tracking methods, and their role for moisture transports into the continent
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DOI：
10.1080/16000870.2018.1454808
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发表时间：
2018-04-06
影响因子：
2
通讯作者：
Simmonds, Ian
中科院分区：
文献类型：
--
作者：
Grieger, Jens;Leckebusch, Gregor C.;Simmonds, Ian
亚南极的热带外气旋在热量和水分向极地输送进入南极洲的过程中起着核心作用，而后者是南极冰盖物质平衡的关键组成部分。由于该地区的气候发生了重大变化，预计这些天气特征的特征将发生变化。有许多不同的方法用于识别和跟踪气旋，这可能导致关于气旋变异性和趋势以及驱动这些特征的机制的不同结论。鉴于此，评估14种最先进的气旋识别和跟踪方法之间的共识水平是及时的。我们与1979-2008年期间的ERA-Interim数据集进行了比较，发现不同方法识别的轨道数量存在很大差异，但系统密度的空间格局大致一致。我们的分析证实了文献中提出的大尺度变率模态（如南环模态（SAM））与亚南极气旋之间的联系。气旋路径数量的趋势显示出更加多样化的情况。在南纬60度以南地区，几乎所有方法都发现了强劲的趋势，这主要是由于与SAM有很强的关系，而在南纬60度以南地区，这些方法在趋势的统计显著性上不一致。当比较仅限于较强的气旋时，方法之间的一致性更大。与这些强天气系统有关的水汽通量分析证实了这一点。我们的研究结果表明，应该使用多种气旋识别和跟踪方法来获得关于气旋特征趋势及其与亚南极地区大尺度环流关系的可靠结论。
Extra-tropical cyclones in the subantarctic play a central role in the poleward transport of heat and moisture into Antarctica, with the latter being a key component of the mass balance of the Antarctic ice sheet. As the climate in this region undergoes substantial changes, it is anticipated that the character of these synoptic features will change. There are a number of different methods used to identify and track cyclones, which can potentially lead to different conclusions as to cyclone variability and trends, and mechanisms which drive these features. Given this, it is timely to assess the level of consensus among 14 state-of-the-art cyclone identification and tracking methods. We undertake this comparison with the ERA-Interim data-set for the period 1979-2008 and find large differences in the number of tracks identified by different methods, but the spatial patterns of the system density broadly agree. Links between large-scale modes of variability, such as the Southern Annular Mode (SAM), and subantarctic cyclones as suggested in the literature are confirmed by our analysis. Trends in the number of cyclone tracks show a more diverse picture. Robust trends are identified by almost all methods for austral summer over the region south to 60 degrees S, mainly due to the strong relation to SAM, whereas in austral winter the methods disagree in the statistical significance of the trends. The agreement among the methods is greater when the comparison is confined to the stronger cyclones. This is confirmed by a moisture flux analysis associated with these strong synoptic systems. Our results indicate that multiple cyclone identification and tracking methods should be used to obtain robust conclusions for trends in cyclone characteristics as well as their relation to the large-scale circulation in the subantarctic region.