Ensemble prediction of Mediterranean high-impact events using potential vorticity perturbations. Part II: Adjoint-derived sensitivity zones

Vich, M.; Romero, R.; Homar, V.

doi:10.1016/j.atmosres.2011.07.016

Cited by 11 publications

(13 citation statements)

References 46 publications

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“…Both ensembles exhibit greater forecasting skill than a multiphysics EPS and a deterministic run when tested within a collection of highimpact MEDEX (Mediterranean Experiment on cyclones that produce high-impact weather in the Mediterranean, a project endorsed by the WMO under the THORPEX WWRP, http://medex.aemet.uib.es. cyclonic episodes; Vich et al, 2011aVich et al, , 2011b. Other studies that focus on modifying the PV field according to WV imagery show its positive effect on reducing forecast error (e.g.…”

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%

“…This climatology provides a PV perturbation range consistent with the actual PV field uncertainties in order to randomly increase/decrease the PV field intensity and displace its features on the regions highlighted by each method. Both ensembles proved to be skilful when tested for the precipitation field over 19 MEDEX cyclonic episodes, even though the PV-gradient ensemble was generally better than the more computationally expensive PV-adjoint EPS (see details in the study by Vich et al, 2011aVich et al, , 2011b.…”

Section: Alternative Pv Modification Techniquesmentioning

confidence: 99%

“…Specifically, several verification scores, like ROC curves or Taylor diagrams, will evaluate the performance of the technique using the 9Á10 June 2000 and 9Á10 October 2002 events, both from the MEDEX database. Additionally, the PV modification techniques used on the two EPSs shown in the study of Vich et al (2011aVich et al ( , 2011b represent a remarkable benchmark to compare with the PV-WV technique used in this study.…”

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%

“…Huo et al, 1999;Homar et al, 2003;Romero, 2008). Moreover, Vich et al (2011aVich et al ( , 2011b present two ensemble prediction systems (EPSs) based on perturbing the initial and boundary conditions of the MM5 PV field. The PV perturbations are set from a PV error climatology that characterizes typical PV errors in the ECMWF nesting data, both in intensity and displacement.…”

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%

“…Two additional PV modification methods taken from the work of Vich et al (2011aVich et al ( , 2011b are used to generate ensemble predictions of the case studies by perturbing the model initial and boundary conditions. The perturbations are applied over the PV field, exploiting the connection between PV anomalies and cyclones.…”

Section: Alternative Pv Modification Techniquesmentioning

confidence: 99%

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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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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%

Section: Alternative Pv Modification Techniquesmentioning

confidence: 99%

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%

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%

Section: Alternative Pv Modification Techniquesmentioning

confidence: 99%

See 3 more Smart Citations

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

View full text Add to dashboard Cite

show abstract

Role of mesoscale factors at the onset of deep convection on hailstorm days and their relation to the synoptic patterns

García‐Ortega

Merino

López

et al. 2012

Atmospheric Research

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Using a deterministic time-lagged ensemble forecast with a probabilistic threshold for improving 6–15day summer precipitation prediction in China

Wei

Wang

et al. 2015

Atmospheric Research

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A Deterministic Time-lagged Ensemble Forecast using a Probabilistic Threshold (DEFPT) method is suggested for improving summer 6-15 day categorical precipitation prediction in China from the Beijing Climate Center Atmospheric General Circulation Model version 2.1 (BCC_AGCM2.1). It is based on a time-lagged ensemble system that consists of 13 ensemble members separated sequentially at 6 hour intervals lagging the last three days. The DEFPT is not intended to predict the probability of rainfall, but rather to forecast rainfall (yes/no) occurrence for different categories of precipitation at any model grid box. A given categorical precipitation is forecasted to occur at one gridbox only when the ensemble probability for that categorical precipitation exceeds a certain threshold. This method is useful for providing an estimate of whether precipitation events will occur to decision-makers based on probabilistic forecasts during days 6-15. A large number of hindcast experiments for 1996-2005 summers reveal that this threshold can be best (and empirically) set as 5/13 and 4/13 respectively for the 6-15 day prediction of 1+ mm (i.e., above 1 mm per day) and 5+ mm rainfall events, using the Relative Operating Characteristic (ROC) curve, the Equitable Threat Score (ETS), the Hanssen and Kuipers (HK) score, and frequency bias (BIA) to achieve best prediction performance. With this set of thresholds, the DEFPT shows skill improvement over the corresponding single deterministic forecast using one initial value and the Time-Lagged Average Forecast (LAF) ensemble method. Similar improvements by the DEFPT are also found for the prediction of several other categories of precipitation between 1+ mm and 10+ mm per day. Application of DEFPT to larger ensemble size and BCC_AGCM version 2.2 with a higher horizontal resolution also demonstrates the effectiveness of the DEFPT for 6-15 day categorical precipitation forecasts.

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Ensemble prediction of Mediterranean high-impact events using potential vorticity perturbations. Part II: Adjoint-derived sensitivity zones

Cited by 11 publications

References 46 publications

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

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

Role of mesoscale factors at the onset of deep convection on hailstorm days and their relation to the synoptic patterns

Using a deterministic time-lagged ensemble forecast with a probabilistic threshold for improving 6–15day summer precipitation prediction in China

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