Compound warm–dry and cold–wet  events over the Mediterranean

Luca, Paolo De; Messori, Gabriele; Faranda, Davide; Ward, Philip J.; Coumou, Dim

doi:10.5194/esd-11-793-2020

Cited by 76 publications

(61 citation statements)

References 73 publications

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“…This method results in a spin‐up time of 6 hr before incorporating any of the model outputs into the analysis. Although ERA5 provides modelled data, this dataset has already been used for extreme precipitation‐related studies over the Mediterranean (De Luca et al ., 2020). Appendix A provides the analysis of connecting localized EPEs to large‐scale patterns using the precipitation derived from the E‐OBS dataset (Cornes et al ., 2018), a product based on observational data.…”

Section: Datamentioning

confidence: 99%

Extreme precipitation events in the Mediterranean: Spatiotemporal characteristics and connection to large‐scale atmospheric flow patterns

Mastrantonas

Herrera‐Lormendez

Magnusson

et al. 2021

Intl Journal of Climatology

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The Mediterranean region is strongly affected by extreme precipitation events (EPEs), sometimes leading to severe negative impacts on society, economy, and the environment. Understanding such natural hazards and their drivers is essential to mitigate related risks. Here, EPEs over the Mediterranean between 1979 and 2019 are analysed, using ERA5, the latest reanalysis dataset from ECMWF. EPEs are determined based on the 99th percentile of their daily distribution (P99). The different EPE characteristics are assessed, based on seasonality and spatiotemporal dependencies. To better understand their connection to large‐scale atmospheric flow patterns, Empirical Orthogonal Function analysis and subsequent non‐hierarchical K‐means clustering are used to quantify the importance of weather regimes to EPE frequency. The analysis is performed for different variables, depicting atmospheric variability in the lower and middle troposphere. Results show a clear spatial division in EPE occurrence, with winter and autumn being the seasons of highest EPE frequency for the eastern and western Mediterranean, respectively. There is a high degree of temporal dependencies with 20% of the EPEs (median value based on all studied grid cells), occurring up to 1 week after a preceding P99 event at the same location. Local orography is a key modulator of the spatiotemporal connections and substantially enhances the probability of co‐occurrence of EPEs even for distant locations. The clustering clearly demonstrates the prevalence of distinct synoptic‐scale atmospheric conditions during the occurrence of EPEs for different locations within the region. Results indicate that clustering, based on a combination of sea level pressure (SLP) and geopotential height at 500 hPa (Z500), can increase the conditional probability of EPEs by more than three (3) times (median value for all grid cells) from the nominal probability of 1% for the P99 EPEs. Such strong spatiotemporal dependencies and connections to large‐scale patterns can support extended‐range forecasts.

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Section: Datamentioning

confidence: 99%

Extreme precipitation events in the Mediterranean: Spatiotemporal characteristics and connection to large‐scale atmospheric flow patterns

Mastrantonas

Herrera‐Lormendez

Magnusson

et al. 2021

Intl Journal of Climatology

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“…For more detailed discussions on this topic and a comparison to the conventional idea of predictability as evaluated through numerical weather forecasts, see Messori et al (2017), Scher and Messori (2018), and Faranda et al (2019a). Both d and θ −1 may in principle be computed for more than one climate variable jointly (Faranda et al, 2020;De Luca et al, 2020b, a), but here we will focus on their univariate implementation.…”

Section: A Qualitative Overview Of the Dynamical Systems Frameworkmentioning

confidence: 99%

Technical note: Characterising and comparing different palaeoclimates with dynamical systems theory

Messori

Faranda

2021

Clim. Past

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Abstract. Numerical climate simulations produce vast amounts of high-resolution data. This poses new challenges to the palaeoclimate community – and indeed to the broader climate community – in how to efficiently process and interpret model output. The palaeoclimate community also faces the additional challenge of having to characterise and compare a much broader range of climates than encountered in other subfields of climate science. Here we propose an analysis framework, grounded in dynamical systems theory, which may contribute to overcoming these challenges. The framework enables the characterisation of the dynamics of a given climate through a small number of metrics. These may be applied to individual climate variables or to several variables at once, and they can diagnose properties such as persistence, active number of degrees of freedom and coupling. Crucially, the metrics provide information on instantaneous states of the chosen variable(s). To illustrate the framework's applicability, we analyse three numerical simulations of mid-Holocene climates over North Africa under different boundary conditions. We find that the three simulations produce climate systems with different dynamical properties, such as persistence of the spatial precipitation patterns and coupling between precipitation and large-scale sea level pressure patterns, which are reflected in the dynamical systems metrics. We conclude that the dynamical systems framework holds significant potential for analysing palaeoclimate simulations. At the same time, an appraisal of the framework's limitations suggests that it should be viewed as a complement to more conventional analyses, rather than as a wholesale substitute.

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“…Our approach can potentially be used to detect how vulnerability at monthly scale within the year changes in future due to the alterations in climatic conditions and the phenological cycle. Hot and dry days are getting more persistent in summer, but droughts and warm spells are increasing in spring as well (de Luca et al, 2020;Vogel et al, 2021), which can have detrimental implications for the Mediterranean ecosystems as spring is the main growing season. With temperature increases in future, vulnerability to cold conditions might be constrained to a shorter time frame, whereas the time span with vulnerability to hot conditions might expand within the year.…”

Section: Interpretation Of Temporal and Spatial Patterns In The Meditmentioning

confidence: 99%

Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean

Vogel¹,

Paton²,

Aich³

2021

Preprint

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Abstract. Mediterranean ecosystems are particularly vulnerable to climate change and the associated increase in climate extremes. This study investigates extreme ecosystem responses evoked by climatic drivers in the Mediterranean Basin for the time span 1999–2019 with a specific focus on seasonal variations, as the seasonal timing of climatic anomalies is considered essential for impact and vulnerability assessment. A bivariate vulnerability analysis is performed for each month of the year to quantify which combinations of the drivers temperature (obtained from ER5 Land) and soil moisture (obtained from ESA CCI and ERA5 Land) lead to extreme reductions of ecosystem productivity using the fraction of absorbed photosynthetically active radiation (FAPAR; obtained from Copernicus Global Land Service) as a proxy. The bivariate analysis clearly showed that, in many cases, it is not just one but a combination of both drivers that causes ecosystem vulnerability. The overall pattern shows that Mediterranean ecosystems are prone to three soil moisture regimes during the yearly cycle: They are vulnerable to hot and dry conditions from May to July, to cold and dry conditions from August to October, and to cold conditions from November to April, illustrating the shift from a soil moisture-limited regime in summer to an energy-limited regime in winter. In late spring, a month with significant vulnerability to hot conditions only often precedes the next stage of vulnerability to both hot and dry conditions, suggesting that high temperatures lead to critically low soil moisture levels with a certain time lag. In the eastern Mediterranean, the period of vulnerability to hot and dry conditions within the year is much longer than in the western Mediterranean. Our results show that it is crucial to account for both spatial and temporal variability to adequately assess ecosystem vulnerability. The seasonal vulnerability approach presented in this study helps to provide detailed insights regarding the specific phenological stage of the year in which ecosystem vulnerability to a certain climatic condition occurs.

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Compound warm–dry and cold–wet events over the Mediterranean

Cited by 76 publications

References 73 publications

Extreme precipitation events in the Mediterranean: Spatiotemporal characteristics and connection to large‐scale atmospheric flow patterns

Extreme precipitation events in the Mediterranean: Spatiotemporal characteristics and connection to large‐scale atmospheric flow patterns

Technical note: Characterising and comparing different palaeoclimates with dynamical systems theory

Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean

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