Our understanding of the time variability of intense cyclones in the Mediterranean region is still lacking despite its importance for the long-term forecast of climate anomalies. This study examines the month-to-month variability and predictability of cyclones, the intensity of which exceeded the 75th percentile (intense cyclones) and the 95th percentile (extreme cyclones), over the Western and Eastern Mediterranean. The locations of cyclones were obtained by applying the method of M. Yu. Bardin on the 6-hourly 1000 hPa geopotential height data from the NCEP/NCAR reanalysis for the period 1951–2017 (67 years). It was shown that annual frequencies of cyclones were higher in the Western Mediterranean due to the contribution of spring and autumn; monthly averages were higher in the Eastern Mediterranean in December/January–March for intense/extreme cyclones. In the context of global warming, no linear trends significant at the 90% confidence level were found in the variability of intense and extreme cyclones, except for a positive trend in autumn extreme cyclones over the Eastern Mediterranean. The time series of cyclones in both parts of the Mediterranean were characterized by a pronounced interannual variability with a noticeable decadal modulation. According to spectral analysis, these interannual periods were multiples of 2–3 years corresponding to the main global teleconnection patterns. Seasonally, the most energy was concentrated in winter spectra; spring and autumn spectra had lower comparable magnitudes. The correlation analysis between the frequency of cyclones and the indices of the main atmospheric patterns showed that the main synchronous patterns for intense and extreme Mediterranean cyclones in September–April were the Mediterranean Oscillation (with the opposite signs for the Western and Eastern Mediterranean), Scandinavia pattern (positive correlation), and East Atlantic Oscillation (negative correlation). Additional important synchronous teleconnection patterns for some months were the Arctic Oscillation and East Atlantic/West Russia pattern for the Western Mediterranean, and the Polar/Eurasia pattern and Tropical Northern Hemisphere pattern for the Eastern Mediterranean. The outcome of this paper was the use of an artificial neural network model with inputs of global teleconnection indices both in the atmosphere and ocean to describe the temporal variability of the frequency of intense cyclones in the Western and Eastern Mediterranean. The predictability of intense cyclones was shown with the possibility of forecasts with a lead time of 0, 2, 4, and 6 months for the Western Mediterranean in October, January, February, April, and May, and for the Eastern Mediterranean in January, February, March, April, and May. One of the applications of this model may be in forecasting the evolution of the monthly frequency of cyclones with a lead time of 2 to 6 months.

中文翻译：

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西地中海和东地中海强气旋的时间变化和可预测性

尽管对气候异常的长期预测很重要，但我们对地中海地区强气旋的时间变异性仍然缺乏了解。这项研究检查了气旋的月度变化和可预测性，其强度超过了西地中海和东地中海的第 75 个百分点（强气旋）和第 95 个百分点（极端气旋）。应用M. Yu的方法获得了气旋的位置。Bardin 关于 1951-2017 年（67 年）期间 NCEP/NCAR 再分析的 6 小时 1000 hPa 位势高度数据。结果表明，由于春季和秋季的贡献，西地中海地区气旋的年发生频率较高；12 月/1 月至 3 月东地中海的月平均值更高，因为强/极端气旋。在全球变暖的背景下，除东地中海秋季极端气旋呈正趋势外，强烈和极端气旋的变化没有发现在 90% 置信水平上显着的线性趋势。地中海两地气旋的时间序列具有明显的年际变化和明显的年代际调制。根据光谱分析，这些年际周期是 2-3 年的倍数，对应于主要的全球遥相关模式。季节性地，大部分能量集中在冬季光谱；春季和秋季光谱具有较低的可比幅度。气旋频率与主要大气模式指数的相关性分析表明，9-4月强烈和极端地中海气旋的主要同步模式是地中海涛动（西地中海和东地中海符号相反），斯堪的纳维亚模式（正相关）和东大西洋涛动（负相关）。几个月来其他重要的同步遥相关模式是西地中海的北极涛动和东大西洋/西俄罗斯模式，以及东地中海的极地/欧亚模式和热带北半球模式。本文的结果是使用人工神经网络模型，输入大气和海洋中的全球遥相关指数，以描述西地中海和东地中海强烈气旋频率的时间变化。强气旋的可预测性表明，西地中海 10 月、1 月、2 月、4 月和 5 月以及东地中海 1 月的提前期分别为 0、2、4 和 6 个月，二月、三月、四月和五月。该模型的应用之一可能是预测提前 2 至 6 个月的气旋每月频率的演变。强气旋的可预测性表明，西地中海 10 月、1 月、2 月、4 月和 5 月以及东地中海 1 月的提前期分别为 0、2、4 和 6 个月，二月、三月、四月和五月。该模型的应用之一可能是预测提前 2 至 6 个月的气旋每月频率的演变。强气旋的可预测性表明，西地中海 10 月、1 月、2 月、4 月和 5 月以及东地中海 1 月的提前期分别为 0、2、4 和 6 个月，二月、三月、四月和五月。该模型的应用之一可能是预测提前 2 至 6 个月的气旋每月频率的演变。