Application of a potential vorticity modification method to a case of rapid cyclogenesis over the Atlantic Ocean

Manders, Astrid; Verkley, W. T. M.; Diepeveen, J. J.; Moene, A. R.

doi:10.1002/qj.139

Cited by 8 publications

(7 citation statements)

References 17 publications

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“…Demirtas and Thorpe, 1999;Hello and Arbogast, 2004;Guerin et al, 2006;Kristjánsson, 2006, 2008;Manders et al, 2007) have shown that initial conditions corrected by PV modifications according to WV imagery may lead to substantial reduction of the forecast errors. In these earlier investigations, the authors placed special emphasis on deep North Atlantic cyclones that were poorly forecast by operational meteorological centres.…”

Section: Introductionmentioning

confidence: 99%

Improving the numerical prediction of a cyclone in the Mediterranean by local potential vorticity modifications

Argence

Lambert

Richard

et al. 2009

Quart J Royal Meteoro Soc

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This study explores the benefit that can be drawn from incorporating local potential vorticity (PV) modifications into a numerical forecast. The case under study is the severe cyclogenesis that occurred in the Western Mediterranean from 9 to 12 November 2001. This case was shown to be extremely sensitive to the upper-level flow, which governed to a great extent the deepening of the depression and the location and intensity of its associated precipitation. Corrections of PV were guided by METEOSAT-7 water vapour observations and restricted to the upper troposphere, mainly altering the topography of the dynamical tropopause. Using both the French operational global model ARPEGE and the non-hydrostatic mesoscale model Meso-NH, it is shown that carefully designed PV corrections lead to a substantial improvement in the simulation of the storm, both in terms of surface pressure, cloud cover and precipitation forecasts. Furthermore, the impact of the modifications is shown to be a maximum when they are introduced at the time corresponding to the incipient stage of cyclogenesis.

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Section: Introductionmentioning

confidence: 99%

Improving the numerical prediction of a cyclone in the Mediterranean by local potential vorticity modifications

Argence

Lambert

Richard

et al. 2009

Quart J Royal Meteoro Soc

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“…Other studies that focus on modifying the PV field according to WV imagery show its positive effect on reducing forecast error (e.g. Dermitas and Thorpe, 1999;Hello and Arbogast, 2004;Gue´rin et al, 2006;Kristja´nson, 2006, 2008;Manders et al, 2007;Argence et al, 2009). This paper evaluates the forecast results obtained using the PV-WV technique when applied to two different Mediterranean high-impact weather (HIW) events.…”

Section: P U B L I S H E D B Y T H E I N T E R N a T I O N A L M E T mentioning

confidence: 99%

Perturbing the potential vorticity field in mesoscale forecasts of two Mediterranean heavy precipitation events

Vich

Romero

Richard

et al. 2012

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C TIn order to improve the quality of the Mediterranean high-impact weather (HIW) numerical predictions, this study proposes to modify the potential vorticity (PV) field of the model initial state, taking advantage of information provided by the water vapour (WV) channel of the METEOSAT-7 satellite. The implemented PV field modifications aim to reduce the mismatch between the upper-level PV features and the WV brightness temperatures guided by the known relation between these two fields (PV-WV technique). The PV-WV technique effectiveness is evaluated on two HIW events, and is also compared with two additional PV modification techniques from an earlier study. The chosen episodes occurred on 9Á10 June 2000 and 9Á10 October 2002 and produced heavy precipitation over both Spain and France. The main difference between these two episodes is found in the driving mechanism, a mesoscale cyclone for the June 2000 event and a larger low-pressure centre for the October 2002 case. The two additional PV modification techniques introduce perturbations along the zones highlighted by the MM5 adjoint model calculated sensitivity zones (PV-adjoint) and along the three-dimensional PV structure presenting the locally most intense values and gradients of the field (PV-gradient). A close examination of both case studies of the forecast rainfall fields and several objective verification indices show that the PV-WV technique performance exceeds the control (or non-perturbed) forecast skill while remaining inside the distribution obtained by both PV-gradient and PV-adjoint techniques. This PV-WV technique could be used to increase the ensemble spread introducing higher amplitude modifications. Thus, a more skilled ensemble prediction system could be built by taking advantage of the subjectivity inherent to this method (manual perturbations) and also of the uncertainty present in the initial state.

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“…Modification of the potential vorticity is a common way to perturb the atmospheric fields. Manders et al (2007) used this method to modify numerical weather forecasts to assess numerical errors within forecasts.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Heavy Precipitation Forecasts to Small Modifications of Large-Scale Weather Patterns for the Elbe River

Schlüter

Schädler

2010

Journal of Hydrometeorology

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Extreme flood events are caused by long-lasting and/or intensive precipitation. The detailed knowledge of the distribution, intensity, and spatiotemporal variability of precipitation is, therefore, a prerequisite for hydrological flood modeling and flood risk management. For hydrological modeling, temporal and spatial high-resolution precipitation data can be provided by meteorological models. This study deals with the question of how small changes in the synoptic situation affect the characteristics of extreme forecasts. For that purpose, two historic extreme precipitation events were hindcasted using the Consortium for Small Scale Modeling (COSMO) model of the German Weather Service (DWD) with different grid resolutions (28, 7, and 2.8 km), where the domains with finer resolutions were nested into the ones with coarser resolution. The results show that the model is capable of simulating such extreme precipitation events in a satisfactory way. To assess the impact of small changes in the synoptic situations on extreme precipitation events, the large-scale atmospheric fields were shifted to north, south, east, and west with respect to the orography by about 28 and 56 km, respectively, in one series of runs while in another series, the relative humidity and temperature were increased to modify the amount of precipitable water. Both series were performed for the Elbe flood events in August 2002 and January 2003, corresponding to two very different synoptic situations. The results show that the modeled precipitation can be quite sensitive to small changes of the synoptic situation with changes in the order of 20% for the maximum daily precipitation and that the types of synoptic situations play an important role. While van Bebber weather conditions, of Mediterranean origin, were quite sensitive to modifications, more homogeneous weather patterns were less sensitive.

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Application of a potential vorticity modification method to a case of rapid cyclogenesis over the Atlantic Ocean

Cited by 8 publications

References 17 publications

Improving the numerical prediction of a cyclone in the Mediterranean by local potential vorticity modifications

Improving the numerical prediction of a cyclone in the Mediterranean by local potential vorticity modifications

Perturbing the potential vorticity field in mesoscale forecasts of two Mediterranean heavy precipitation events

Sensitivity of Heavy Precipitation Forecasts to Small Modifications of Large-Scale Weather Patterns for the Elbe River

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