A numerical study of the first phase of a deep Mediterranean cyclone: Cyclogenesis in the lee of the Atlas Mountains

Horvath, Kristian; Fita, L.; Romero, R.; Ivančan-Picek, Branka

doi:10.1127/0941-2948/2006/0113

Cited by 30 publications

(23 citation statements)

References 26 publications

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“…In this study the role of three major anomalies is analysed: (1) the upper level positive PV anomaly related to the two main upper level disturbances, (2) upper level negative PV anomaly related to the North Atlantic high and (3) the surface thermal anomaly related to the initial baroclinicity of the environment. Theoretically, a positive(negative) surface thermal anomaly can be related to a formal positive(negative) PV anomaly located below the bottom boundary (Bretherton, 1966;Thorpe, 1986;Reed et al, 1992;Horvath et al, 2006). In practice, the surface thermal anomaly is introduced as a bottom boundary field in the PV inversion method.…”

Section: Objective Quantification Of Perturbationsmentioning

confidence: 99%

Objective quantification of perturbations produced with a piecewise PV inversion technique

2007

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Abstract. PV inversion techniques have been widely used in numerical studies of severe weather cases. These techniques can be applied as a way to study the sensitivity of the responsible meteorological system to changes in the initial conditions of the simulations. Dynamical effects of a collection of atmospheric features involved in the evolution of the system can be isolated. However, aspects, such as the definition of the atmospheric features or the amount of change in the initial conditions, are largely case-dependent and/or subjectively defined. An objective way to calculate the modification of the initial fields is proposed to alleviate this problem. The perturbations are quantified as the mean absolute variations of the total energy between the original and modified fields, and an unique energy variation value is fixed for all the perturbations derived from different PV anomalies. Thus, PV features of different dimensions and characteristics introduce the same net modification of the initial conditions from an energetic point of view. The devised quantification method is applied to study the high impact weather case of 9-11 November 2001 in the Western Mediterranean basin, when a deep and strong cyclone was formed. On the Balearic Islands 4 people died, and sustained winds of 30 ms −1 and precipitation higher than 200 mm/24 h were recorded. Moreover, 700 people died in Algiers during the first phase of the event. The sensitivities to perturbations in the initial conditions of a deep upper level trough, the anticyclonic system related to the North Atlantic high and the surface thermal anomaly related to the baroclinicity of the environment are determined. Results reveal a high influence of the upper level trough and the surface thermal anomaly and a minor role of the North Atlantic high during the genesis of the cyclone.

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Section: Objective Quantification Of Perturbationsmentioning

confidence: 99%

Objective quantification of perturbations produced with a piecewise PV inversion technique

2007

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“…In Horvath et al (2006), the roles of orography, surface sensible heat flux and upper level potential vorticity anomaly are isolated using the factor separation method for the analysis of an intense cyclone that produced extremely strong Bora winds. This cyclone was generated in the lee of the Atlas Mountains and fully developed over the central Mediterranean.…”

Section: Dynamical and Physical Mechanisms -Numerical Modellingmentioning

confidence: 99%

MEDEX: a general overview

Jansà

Alpert

Arbogast

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. The general objective of the international MEDiterranean EXperiment (MEDEX) was the better understanding and forecasting of cyclones that produce high impact weather in the Mediterranean. This paper reviews the motivation and foundation of MEDEX, the gestation, history and organisation of the project, as well as the main products and scientific achievements obtained from it. MEDEX obtained the approval of World Meteorological Organisation (WMO) and can be considered as framed within other WMO actions, such as the ALPine EXperiment (ALPEX), the Mediterranean Cyclones Study Project (MCP) and, to a certain extent, THe Observing System Research and Predictability EXperiment (THORPEX) and the HYdrological cycle in Mediterranean EXperiment (HyMeX). Through two phases (2000-2005 and 2006-2010), MEDEX has produced a specific database, with information about cyclones and severe or high impact weather events, several main reports and a specific data targeting system field campaign (DTS-MEDEX-2009). The scientific achievements are significant in fields like climatology, dynamical understanding of the physical processes and social impact of cyclones, as well as in aspects related to the location of sensitive zones for individual cases, the climatology of sensitivity zones and the improvement of the forecasts through innovative methods like mesoscale ensemble prediction systems.

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“…Besides, generally over the African-European-Asian region, in southern mid-latitudes, the tropical moisture export contributes up to 60% to climatological precipitation [2]. The orography in those regions plays also a role in the creation and enhancement of the cyclogenesis [3]. The latter can result from complex interaction of upper-level synoptic flow and local topography.…”

Section: Introductionmentioning

confidence: 99%

Dynamical contribution of mean potential vorticity pseudo-observations derived from MetOp/GOME2 ozone data into short-range weather forecast during high precipitation events

Sbii

Zazoui

Semane

2015

IJBAS

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Satellites are uniquely capable of providing uniform data coverage globally. Motivated by such capability, this study builds on a previously described methodology that generates numerical weather prediction initial conditions from satellite total column ozone data. The methodology is based on two principal steps. Firstly, the studied linear regression between vertical (100hPa-500hPa) Mean Potential Vorticity (MPV) and MetOp/GOME2 total ozone data (O3) generates MPV pseudo-observations. Secondly, the 3D variational (3D-Var) assimilation method is designed to take into account MPV pseudo-observations in addition to conventional observations. After a successful assimilation of MPV pseudo-observations using a 3D-Var approach within the Moroccan version of the ALADIN limited-area model, the present study aims to assess the dynamical behavior of the short-range forecast at upper levels during heavy precipitation events (HPEs). It is found that MPV assimilation offers the possibility to internally monitor the model upper-level dynamics in addition to the use of Water Vapor Satellite images.

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A numerical study of the first phase of a deep Mediterranean cyclone: Cyclogenesis in the lee of the Atlas Mountains

Cited by 30 publications

References 26 publications

Objective quantification of perturbations produced with a piecewise PV inversion technique

Objective quantification of perturbations produced with a piecewise PV inversion technique

MEDEX: a general overview

Dynamical contribution of mean potential vorticity pseudo-observations derived from MetOp/GOME2 ozone data into short-range weather forecast during high precipitation events

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