Extended Abstract (3.1M)3.5
Sensitivities of an intense cyclone over the Western Mediterranean
Victor Homar, NOAA/NSSL, Norman, OK; and D. J. Stensrud
The Mediterranean is well known as an active cyclogenetic region.On November 10-11 2001 an intense cyclone crossed northwards the Western Mediterranean, producing a mesoscale-sized region of strong damaging winds over eastern Spain. The numerical simulation of this type of event is usually hampered by the lack of observations over the Mediterranean Sea,north Africa and the Atlantic Ocean. To evaluate more accurately the regions in which the model simulations are influenced by this lack of data, the MM5 adjoint system is used to determine the most sensitive areas within the initial conditions of the simulation of this November 10-11 event. The study tracks back the sensitivities shown by different simulation times using parameters characterizing the cyclone intensity. The validity of the adjoint model results is tested by perturbing the full nonlinear model's initial conditions using the sensitivity fields as guidance. This analysis documents and helps to quantify the limitations of the linear information when applied to the full nonlinear model. Results reveal that the areas which show the largest sensitivities are located over north Africa for the 12- and 24-h simulations, whereas southwestern and western Europe emerge as areas with important sensitivities for the longer 36- and 48-h simulations. Mesoscale details regarding the shape and intensity of an upper-level trough, as well as a low level cold front, are highlighted by the adjoint runs as the structures which influence most strongly the development of the intense mediterranean cyclone and the damaging surface winds it produces.
Session 3, Mesoscale Predictability II
Tuesday, 24 June 2003, 8:30 AM-10:15 AM
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