The Climatological Impact of Recurving North Atlantic Tropical Cyclones on Downstream Extreme Precipitation Events

Pohorsky, Roman; Röthlisberger, Matthias; Grams, Christian M.; Riboldi, Jacopo; Martius, Olivia

doi:10.1175/mwr-d-18-0195.1

Cited by 22 publications

(33 citation statements)

References 55 publications

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“…Many studies have investigated the dynamics of such individual events, while fewer tried to find an association between the evolution of large‐scale dynamical features and EPEs on the Alpine area based on a large sample of dates (say >100 cases, see for example Martius et al ., 2006a; Grazzini, 2007; Pinto et al ., 2013; Pohorsky et al ., 2019). Nevertheless, the linkage between extreme precipitation in the Alpine area and the presence of a large‐amplitude wave or potential vorticity (PV) streamer over western Europe is well established.…”

Section: Introductionmentioning

confidence: 99%

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Extreme precipitation events over northern Italy. Part II: Dynamical precursors

Grazzini

Fragkoulidis

Teubler

et al. 2021

Quart J Royal Meteoro Soc

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The connection between weather extremes and Rossby wave packets (RWP) has been increasingly documented in recent years. RWP propagation and characteristics can modulate the midlatitude weather, setting the scene for temperature and precipitation extremes and controlling the geographical area affected. Several studies on extreme precipitation events (EPEs) in the Alpine area reported, as the main triggering factor, a meridionally elongated upper‐level trough as part of an incoming Rossby wave packet. In this work, we investigate a wide number of EPEs occurring between 1979 and 2015 in northern‐central Italy. The EPEs are subdivided into three categories (Cat1, Cat2, Cat3) according to thermodynamic conditions over the affected region. It is found that the three categories differ not only in terms of the local meteorological conditions, but also in terms of the evolution and properties of precursor RWPs. These differences cannot be solely explained by the apparent seasonality of the flow; therefore, the relevant physical processes in the RWP propagation of each case are further investigated. In particular, we show that RWPs associated with the strongest EPEs, namely the ones falling in Cat2, undergo a substantial amplification over the western North Atlantic due to anomalous ridge‐building 2 days before the event; arguably due to diabatic heating sources. This type of development induces a downstream trough which is highly effective in focusing water vapour transport toward the main orographic barriers of northern‐central Italy and favouring the occurrence of EPEs.

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Section: Introductionmentioning

confidence: 99%

“…According to Pohorsky et al (2019), strong ridge amplification over the Atlantic appears to be a necessary prerequisite for EPEs over Europe. They show that ridge building could be further enhanced by strong diabatic heating disturbances, like those induced by recurving tropical cyclones (TCs) or associated with strong warm conveyor belts (WCBs).…”

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confidence: 99%

Extreme precipitation events over northern Italy. Part II: Dynamical precursors

Grazzini

Fragkoulidis

Teubler

et al. 2021

Quart J Royal Meteoro Soc

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“…Europe (Ralph et al, 2004(Ralph et al, , 2006Lavers et al, 2013a,b;Waliser and Guan, 2017). Also, IVT has been directly related to precipitation extremes (Moore et al, 2015;Froidevaux and Martius, 2016;Grazzini et al, 2019;Pohorsky et al, 2019;Stucki et al, 2020) and served as a proxy to elucidate moisture transport pathways that feed heavy rainfall events (Swales et al, 2016;Tan et al, 2019). Furthermore, recent studies employed IVT to improve the medium-range prediction of hydrometeorological extremes (Lavers et al, 2014(Lavers et al, , 2016 and to assess (thermo)dynamical changes of precipitation extremes in projected future climates Radic et.…”

Section: Introductionmentioning

confidence: 99%

A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events

Vries¹

2020

Preprint

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Abstract. Extreme precipitation events (EPEs) cause frequently flooding with dramatic socioeconomic impacts in many parts of the world. Previous studies considered two synoptic-scale processes, Rossby wave breaking and intense moisture transport, typically in isolation, and their linkage to such EPEs in several regions. This study presents for the first time a global and systematic climatological analysis of these two synoptic-scale processes, in tandem and in isolation, for the occurrence of EPEs. To this end, we use 40-year ERA-Interim reanalysis data (1979–2018) and apply object-based identification methods for (i) daily EPEs, (ii) stratospheric potential vorticity (PV) streamers as indicators of Rossby wave breaking, and (iii) structures of high vertically integrated horizontal water vapor transport (IVT). First, the importance of these two processes is demonstrated by case studies of previously documented flood events that inflicted catastrophic impacts in different parts of the world. Next, a climatological quantification shows that Rossby wave breaking is associated with > 90 % of EPEs near high topography and over the Mediterranean, intense moisture transport is linked to > 90 % of EPEs over many coastal zones, and their combined occurrence contributes to > 70 % of EPEs in several subtropical and extratropical regions. A more detailed analysis shows that a majority of EPEs associated with (1) only Rossby wave breaking are confined to higher-latitude regions that are deprived from remote moisture supplies by high topography and deserts, (2) only intense moisture transport are found circumglobally at the outer tropics, associated with tropical cyclones, tropical easterly waves, and monsoon lows, (3) combined Rossby wave breaking and intense moisture transport dominate a large part of the globe, in particular over dry subtropical regions where tropical-extratropical interactions are of key relevance, (4) remote, far upstream Rossby wave breaking and intense moisture transport occur over mountainous extratropical west coasts, reminiscent of landfalling atmospheric rivers, and (5) neither of the two synoptic-scale processes are concentrated over the inner tropics and high topography at lower latitudes, where EPEs arise under the influence of local forcing. Accordingly, different combinations of wave breaking and intense moisture transport can reflect a large range of weather systems with relevance to EPEs across various climate zones. Furthermore, the relationship between the PV and IVT characteristics and the precipitation volumes shows that the strength of the wave breaking and moisture transport intensity are intimately connected with the extreme precipitation severity. Finally, composites reveal that subtropical and extratropical EPEs, linked to Rossby wave breaking, go along with the formation of upper-level troughs and cyclogenetic processes near the surface downstream, reduced static stability beneath the upper-level forcing (only over water), and dynamical lifting ahead (over water and land). This study concludes with a concept that reconciles well-established meteorological principles with the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events. The findings of this study may contribute to an improved understanding of the atmospheric processes that lead to EPEs, and may find application in climatic studies on extreme precipitation changes in a warming climate.

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“…The frequency maximum of heated trajectories that pass heavy precipitation areas over eastern North America in autumn could be partially linked to tropical cyclones undergoing extratropical transition (ET). The formation of strong ridges (blocks) downstream of ET cases is well documented (e.g., Grams et al ., 2011; Keller et al ., 2019; Pohorsky et al ., 2019). The frequency maximum in winter could be partially linked to lee cyclones forming in this area (Wernli et al ., 2006; Plante et al ., 2015; Schultz et al ., 2018; Bentley et al ., 2019) and severe winter storms (e.g., Schultz et al ., 2018; Bentley et al ., 2019).…”

Section: Discussionmentioning

confidence: 99%

Quantifying the link between heavy precipitation and Northern Hemisphere blocking—A Lagrangian analysis

Lenggenhager

Martius

2020

Atmospheric Science Letters

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Atmospheric blocks strongly influence surface weather, including extremes such as heat waves and cold spells. Recently, diabatic heating and associated uppertropospheric potential vorticity (PV) modification have been identified as important modulators of atmospheric blocking dynamics. Also, robust links between atmospheric blocks and proximate heavy precipitation events have been established. This leads to the question of the extent to which diabatic heating associated with heavy precipitation events influences Northern Hemisphere blocking. This study uses 5 years of 3-day back trajectories started from objectively identified blocks in the ERA-Interim dataset to investigate this relationship. A substantial fraction of air parcels in blocks pass through heavy precipitation areas. The exact fraction depends on the choice of heavy precipitation threshold. Roughly 19% of all the trajectories in a block pass a heavy precipitation area (>95th percentile) area while being saturated. Of the air parcels in a block that are heated at least 5 K, 60% pass a heavy precipitation area while saturated. This fraction varies with the season and geographical area. The overall fraction is lowest in summer and highest in winter, higher over oceans than over land, and higher over the Pacific than over the Atlantic. In summer, heating is relevant over the continents and heating over North America influences blocks over the eastern Atlantic. For summer blocks in the North Atlantic and over Scandinavia, heating happens partly over the European continent.

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The Climatological Impact of Recurving North Atlantic Tropical Cyclones on Downstream Extreme Precipitation Events

Cited by 22 publications

References 55 publications

Extreme precipitation events over northern Italy. Part II: Dynamical precursors

Extreme precipitation events over northern Italy. Part II: Dynamical precursors

A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events

Quantifying the link between heavy precipitation and Northern Hemisphere blocking—A Lagrangian analysis

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