An intercomparison between a global variable mesh and two limited area models on a case of rapid cyclogenesis
Une intercomparaison entre un modèle global à maille variable et deux modèles à domaine limité sur un cas de cyclogénèse rapide
Cardinali, C. ; Caian, M. ; Pailleux, J. ; Tartaglione, N. ; Buzzi, A. ; Lavagnini, A.
Année de publication
1998
This study has been carried out in order to investigate the <br>predictability of a rapidly developing storm over the Mediterranean <br>area, by comparing the behaviour of three different meteorological <br>models. The models chosen are the global, variable mesh, model ARPEGE, <br>which is running operationally at Metéo-France, and two limited area <br>models, namely ALADIN (also developed at Metéo-France) and BOLAM <br>(developed in Italy, mainly at FISBAT). This comparison study has been <br>performed by a cooperation among the French Meteorological Service and <br>the National Research Council of Italy (CNR) FISBAT and IFA institutes. <br>In this paper we present the results obtained by integrating the models <br>on a short time-range, corresponding to the developing stage of a strong<br> cyclone that moved rather quickly to the North from Northern Africa, <br>associated with perturbed weather and distinct mesoscale features. In <br>particular, this cyclone was characterized by a low-level warm core, <br>associated with very strong winds and precipitation. All the three <br>models were successful in describing the main characteristics of this <br>cyclogenesis event, in particular the rapid evolution of the low level <br>vortex. However, important differences emerged in <img src="http://www.springerlink.com/content/K43656G516716464/xxlarge8220.gif" alt="ldquo" align="MIDDLE" border="0">forecasting<img src="http://www.springerlink.com/content/K43656G516716464/xxlarge8221.gif" alt="rdquo" align="MIDDLE" border="0"> the value of the pressure minimum, its position and time evolution, and the associated distribution of precipitation.When<br> the large scales are treated by using analyzed rather than forecast <br>lateral boundary conditions, the two LAMs perform better than the global<br> model in simulating the low evolution but the global high resolution <br>model better describes the general features of the cyclogenesis.<br></div>Differences<br> in model performance are found especially in the distribution of <br>precipitation forecasts, suggesting two main conclusions: insufficient <br>descriptions of mountains can change the location of the precipitation <br>release, the precipitation scheme of the ALADIN model is sensitive to <br>the lateral boundary conditions. The overestimation of the cyclone in <br>BOLAM seems due to an oversensitivity to the latent heat release that <br>intensifies the circulation in the cyclone core.
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