Predictability Issues of Heavy Alpine South-Side Precipitation

Fehlmann, René; Quadri, C.

doi:10.1007/s007030050017

Cited by 23 publications

(16 citation statements)

References 8 publications

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“…Although slight differences in the upper-level PV distribution can have a large impact on the simulation of heavy precipitation events (e.g. Fehlmann and Quadri, 2000;Romero et al, 2005;Argence et al, 2009), Figure 7 shows that spatial distribution of the precipitation in the Piedmont region is relatively well reproduced by the CHRM. There is a slight eastward shift in the location of the precipitation, which is due to the eastward shift of the PV streamer at 16 November compared to the ECMWF analyses.…”

Section: Meteorological Performance Of Chrm Simulationmentioning

confidence: 99%

“…Massacand et al, 1998;Fehlmann and Quadri, 2000;Richard et al, 2003;Argence et al, 2008;Ducrocq et al, 2008;Nussier et al, 2008;Schlemmer et al, 2010) considered events in autumn or early winter, when the Mediterranean is still relatively warm. This can cause considerable evaporation of moisture, which may be transported towards the Alpine ridge due to the flow induced by an upper-level PV streamer and contribute to the occurrence of such heavy precipitation events.…”

Section: Introductionmentioning

confidence: 99%

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Impact of North Atlantic evaporation hot spots on southern Alpine heavy precipitation events

Winschall

Sodemann

Wernli

2011

Quart J Royal Meteoro Soc

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Section: Meteorological Performance Of Chrm Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of North Atlantic evaporation hot spots on southern Alpine heavy precipitation events

Winschall

Sodemann

Wernli

2011

Quart J Royal Meteoro Soc

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“…The PPVI technique used for this study was originally developed by Fehlmann (1997) and the approach slightly differs from that of Davis (1992). In a nutshell, this PPVI approach is based upon the quasigeostrophic approximation, but takes into account the nonlinearity of the Ertel-PV inversion problem by using an iterative technique.…”

Section: B Piecewise Pv Inversion and Model Runsmentioning

confidence: 99%

“…As demonstrated in Fehlmann and Quadri (2000), these mesoscale substructures are relevant for the forecast quality. They find that forecasts of HP along the Alpine south side are sensitive to the location and amplitude of the southern part of the streamer.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, Fehlmann et al (2000) show that the location, extension, and effective amplitude of mesoscale PV substructures substantially influence precipitation patterns on the Alpine south side (AS). This study builds upon and extends their work by quantifying the effects of the substructure of the streamer on forcing factors a, c, and d, and by addressing their relevance for one specific precipitation event.…”

Section: Introductionmentioning

confidence: 99%

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Disentangling the Forcing Mechanisms of a Heavy Precipitation Event along the Alpine South Side Using Potential Vorticity Inversion

Schlemmer

Martius

Sprenger

et al. 2010

Monthly Weather Review

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Extreme precipitation events along the Alpine south side (AS) are often forced by upper-level positive potential vorticity (PV) anomalies over western Europe. These so-called PV streamers go along with a dynamical forcing for upward motion, a reduction of the static stability in the troposphere (hence facilitating convection), and are associated with low-level winds that transport moisture toward the Alps.A case of heavy precipitation is examined using the 40-yr ECMWF Re-Analysis data. Piecewise PV inversion (PPVI) and the limited-area Climate High Resolution Model (CHRM) are used to assess the influences of mesoscale parts of the streamer on the precipitation event. The impacts on the vertical stability are quantified by the convective available potential energy (CAPE) and an index of static stability. Very sensitive areas in terms of the stability are located beneath the southern tip of the streamer; smaller changes in the stability are observed in the Alpine region.The moisture transport toward the Alps is sensitive to the amplitude of the streamer, which influences the amount of water that can be transported along its eastern flank.The impacts of the topography on the flow are assessed by calculating an average inverse Froude number. Whether or not the air parcels are blocked by or lifted over the barrier (going along with suppressed and enhanced precipitation, respectively) depends on the vertical stability and the impinging wind velocity, two parameters that are inherently linked to the PV streamer and its substructure.

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How important is intensified evaporation for Mediterranean precipitation extremes?

et al. 2014

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The moisture sources for heavy precipitation events in the northwestern Mediterranean are investigated with a Lagrangian moisture source diagnostic, which is based on the analysis of moisture changes during 6 h time intervals along backward trajectories, originating from the location of the heavy precipitation events. We consider the 50 strongest events in each season in the region 0–15°E, 42–46°N during the years 1989–2009. The results of the moisture source diagnostic indicate that during precipitation extremes the Mediterranean Sea surface is only one of several source regions in all seasons, and typically matched by moisture from the North Atlantic in autumn and winter and land evapotranspiration in summer. The event‐to‐event variability is large. Individual events can be dominated by land evapotranspiration, moisture transport from the North Atlantic, or an export of moisture from the tropics. The time of maximum moisture uptake varies between a few hours to more than a week before the precipitation event. The results from the moisture source analysis are used for investigating whether intense surface evaporation occurs prior to heavy precipitation. Surface evaporation anomalies at the moisture sources are positive over the North Atlantic and the European and African land surface, whereas no signal is present over the Mediterranean. Therefore, for the Mediterranean moisture contribution, convergence from the background moisture reservoir is essential, whereas for the remote sources anomalously intense surface evaporation is required to foster the moisture supply for Mediterranean heavy precipitation events.

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Predictability Issues of Heavy Alpine South-Side Precipitation

Cited by 23 publications

References 8 publications

Impact of North Atlantic evaporation hot spots on southern Alpine heavy precipitation events

Impact of North Atlantic evaporation hot spots on southern Alpine heavy precipitation events

Disentangling the Forcing Mechanisms of a Heavy Precipitation Event along the Alpine South Side Using Potential Vorticity Inversion

How important is intensified evaporation for Mediterranean precipitation extremes?

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