Abstract
BackgroundThe El Niño–Southern Oscillation (ENSO) influence over Euro-Mediterranean boreal winter season (December to February) precipitation anomalies has changed along the twentieth century.PurposeThe precipitation anomalies are closely associated with storm track frequency. The changing relationship between the interannual variability of storm track frequency and ENSO is investigated at interannual and multidecadal timescales.MethodsThe Melbourne University cyclone tracking scheme (MS) is applied to reanalyse 200-hPa geopotential height (Z200) datasets to track the winter storms over the Euro-Mediterranean region for the period 1950–2016.ResultsThe maximum of climatological storm track frequency is found to prevail in the study domain with large interannual variability. The multidecadal changes show a phase shift in the relationship between storm track frequency and ENSO from the 1950s to the recent decades. The storm track frequency is negatively correlated (−0.24) to ENSO for the early period (1950–1979), whereas it is positively correlated with a maximum correlation value of 0.44 for the recent period (1987–2016). The correlation departure (0.68) between the two periods shows a significant change in the multidecadal relationship between storm track frequency and ENSO.ConclusionThe ENSO-associated significant changes are noted in the upper and lower tropospheric height anomalies over the North Atlantic and Euro-Mediterranean sector in the recent period with respect to the earlier period, which may largely influencing the storm activity (Frequency/Intensity) and precipitation anomalies over the Euro-Mediterranean region. The findings of this study can have important implications in Euro-Mediterranean seasonal predictability.
Highlights
The El Nino–Southern Oscillation (ENSO) is globally the dominant mode of climatic variability at interannual timescales
The storm track frequency is negatively correlated (-0.24) to ENSO for the early period (1950–1979), whereas it is positively correlated with a maximum correlation value of 0.44 for the recent period (1987–2016)
We found that a significant correlations phase shift occurred after the mid-1985, between Euro-Mediterranean storm track frequency and ENSO
Summary
The El Nino–Southern Oscillation (ENSO) is globally the dominant mode of climatic variability at interannual timescales It has variable effects over the Pacific, North Atlantic, Euro-Mediterranean and tropical regions (Diaz et al 2001; McPhaden et al 2006; Bronnimann 2007; Lopez-Parages and Rodriguez-Fonseca 2012). The ENSO impact over Euro-Mediterranean climate is nonstationary on multidecadal scales and it is contributing to a large interannual variability of storm frequency and precipitation (Bronnimann 2007; Lopez-Parages and Rodriguez-Fonseca 2012; Van-Oldenborgh and Burgers 2005; Herceg Bulic and Kucharski 2012; Ehsan et al 2013). The changing relationship between the interannual variability of storm track frequency and ENSO is investigated at interannual and multidecadal timescales
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