Abstract

Fluctuations in the frequency of cyclones in various regions of the Northern Hemisphere (NH) temperate latitudes on time scales of the order of decades are analyzed in connection with changes in the indices of the leading modes of atmospheric circulation and changes in the zonal transport intensity in individual latitudinal zones. The possible manifestation in cyclone statistics of the well-known thesis about the displacement of storm tracks during warming in the direction of high latitudes is discussed. It is shown that, in general, for the NH temperate latitudes in winter, long-period changes in the frequency of cyclones are irregular fluctuations with scales of several decades, without a visible trend. In summer, the interdecade changes are weakly expressed, but there is a noticeable trend that is significant at the 5% level. In the northern and southern parts of the North Atlantic (NA) in winter, changes in frequency contain significant antiphase components with a period of about 10 years, which correlate well with changes in the North Atlantic Oscillation (NAO) index (the correlation is positive in the northern half; the coefficients are significant at the 0.1% level). Long-period changes in the frequency of cyclones in the North Pacific are generally similar to (but in the opposite phase of) changes in the North Pacific Index by Trenberth and Hurrell. Based on the analysis of a linear regression model, it was found that a significant contribution to changes in the frequency of cyclones in the regions of northern Europe–Western Siberia and the north of ER (ER) in the winter season was made by the circulation modes of the Atlantic–European sector: SCAND, NAO, East Atlantic mode EAM, EAWR (but the EAWR mode contribution is insignificant for the north of Europe–Western Siberia). In summer, for the north of ER and Western Siberia, a significant contribution was made by the SCAND and EAWR circulation modes. An analysis of concomitant changes in zonal wind speed at 700 hPa in the area of the main storm tracks in winter revealed that, for the hemisphere as a whole (0°–360°) in the latitude zone 45°–55° N, as well as in the zone 55°–65° N, changes in zonal wind are determined mainly by changes in the frequency of cyclones in the northern part of the NA and closely follow changes in the NAO. However, in more southern latitudes (35°–45° N), changes in the hemispheric zonal wind are observed, similar to long-period changes in the North Pacific Index in antiphase, the nature of which is unclear (since they do not appear in the Pacific sector itself). The shift of storm tracks to higher latitudes, expected with warming, is observed only for the northern branch of the Atlantic storm track during periods of NAO growth between 1960 and the mid-1990s and after 2010. In general, for the period since 1976, there has been an insignificant trend of about 0.07° latitude per decade.

中文翻译：

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北半球温带地区气旋频率的长期变化

摘要

结合大气环流主导模态指数的变化和北半球温带纬向输送强度的变化，分析了北半球温带各地区气旋频率在数十年量级时间尺度上的波动。个别纬度区域。讨论了关于变暖期间风暴路径向高纬度方向移动的著名论文在气旋统计中的可能表现。结果表明，总体而言，北半球温带冬季气旋频率的长周期变化是数十年尺度的不规则波动，没有明显的趋势。夏季，年代际变化表现较弱，但有明显的趋势，在 5% 水平上显着。冬季北大西洋（NA）北部和南部地区，频率变化含有显着的反相成分，周期约为10年，与北大西洋涛动（NAO）指数的变化有很好的相关性（相关性为正）北半部；系数在 0.1% 水平上显着）。北太平洋气旋频率的长期变化通常与 Trenberth 和 Hurrell 提出的北太平洋指数的变化相似（但相位相反）。通过线性回归模型分析发现，冬季北欧—西西伯利亚和ER（ER）北部地区气旋频率变化的显着贡献是环流。大西洋-欧洲部分的模式：SCAND、NAO、东大西洋模式EAM、EAWR（但EAWR模式对欧洲北部-西西伯利亚的贡献微不足道）。夏季，对于 ER 北部和西西伯利亚来说，SCAND 和 EAWR 环流模式做出了重大贡献。对冬季主风暴路径区域700 hPa纬向风速的伴随变化分析表明，对于北纬45°~55°的半球整体（0°~360°），在北纬55°~65°区域，纬向风的变化主要取决于北半球北部地区气旋频率的变化，并密切关注北纬度的变化。然而，在更南纬地区（35°–45° N），观察到半球纬向风的变化，类似于反相北太平洋指数的长期变化，其性质尚不清楚（因为它们没有出现）太平洋地区本身）。预计随着变暖，风暴路径将向高纬度转移，但仅在 1960 年至 1990 年代中期以及 2010 年之后 NAO 增长期间观察到大西洋风暴路径的北支。总体而言，自 1976 年以来，每十年纬度约 0.07° 的趋势微不足道。