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Archive
by Vich, M.-D.-M., Romero, R., Richard, E., Arbogast, P. and Maynard, K.
Abstract:
In 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 9-10 June 2000 and 9-10 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.
Reference:
Vich, M.-D.-M., Romero, R., Richard, E., Arbogast, P. and Maynard, K., 2012: Perturbing the potential vorticity field in mesoscale forecasts of two Mediterranean heavy precipitation eventsTellus Series A - Dynamic Meteorology and Oceanography, 64, 17224.
Bibtex Entry:
@Article{Vich2012b,
  Title                    = {Perturbing the potential vorticity field in mesoscale forecasts of two Mediterranean heavy precipitation events},
  Author                   = {Vich, M.-D.-M. and Romero, R. and Richard, E. and Arbogast, P. and Maynard, K.},
  Journal                  = {Tellus Series A - Dynamic Meteorology and Oceanography},
  Year                     = {2012},
  Pages                    = {17224},
  Volume                   = {64},

  Abstract                 = {In 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 9-10 June 2000 and 9-10 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.},
  Address                  = {RIPVAGEN 7, JARFALLA, SE-175 64, SWEDEN},
  Affiliation              = {Vich, MDM (Reprint Author), Univ Illes Balears, Dpt Fis, Meteorol Grp, Palma de Mallorca, Spain. Vich, Maria-Del-Mar; Romero, Romualdo, Univ Illes Balears, Dpt Fis, Meteorol Grp, Palma de Mallorca, Spain. Richard, Evelyne, Univ Toulouse, UMR 5560, CNRS, Lab Aerol, Toulouse, France. Arbogast, Philippe; Maynard, Karine, Meteo France, Toulouse, France.},
  Article-number           = {17224},
  Author-email             = {mar.vich@uib.es},
  Copublication            = {5: 2 Es, 3 Fr},
  Doc-delivery-number      = {988WR},
  Doi                      = {10.3402/tellusa.v64i0.17224},
  Funding-acknowledgement  = {Spanish Ministerio de Ciencia e Innovacion {[}BES-2006-14044, MEDICANES CGL2008-01271/CLI]; HYMEX},
  Funding-text             = {Support from PhD grant BES-2006-14044 and MEDICANES CGL2008-01271/CLI project, both from the Spanish Ministerio de Ciencia e Innovacion, as well as the HYMEX project endorsed by the WMO under the GEWEX WCRP and THORPEX WWRP, is acknowledged. The authors would like to thank Jean-Pierre Chaboureau from the Laboratoire d'Aerologie for his help in the METEOSAT-7 data processing. M. Vich is also grateful to Dominique Lambert, Evelyne Richard, and the rest of staff at the Mesoscale Meteorology research group for their hospitality during her stay at the Laboratoire d'Aerologie.},
  ISSN                     = {0280-6495},
  Journal-iso              = {Tellus Ser. A-Dyn. Meteorol. Oceanol.},
  Keywords                 = {PV perturbations; forecast verification; Mediterranean cyclones; METEOSAT-7 water vapour imagery; ensemble prediction systems},
  Keywords-plus            = {NUMERICAL PREDICTION; ENSEMBLE PREDICTION; BOUNDARY-LAYER; WINTER STORMS; PART II; MODEL; SENSITIVITY; CYCLONE; ANOMALIES; CYCLOGENESIS},
  Language                 = {English},
  Number-of-cited-references = {42},
  Owner                    = {hymexw},
  Publisher                = {CO-ACTION PUBLISHING},
  Research-areas           = {Meteorology \& Atmospheric Sciences; Oceanography},
  Researcherid-numbers     = {Richard, Evelyne/G-9506-2011},
  Times-cited              = {0},
  Timestamp                = {2015.07.15},
  Type                     = {Article},
  Unique-id                = {ISI:000307522000001},
  Url                      = {http://www.tellusa.net/index.php/tellusa/article/view/17224},
  Web-of-science-categories = {Meteorology \& Atmospheric Sciences; Oceanography}
}