Authors: Feifan Zhou Mu Mu
Publish Date: 2011/08/19
Volume: 28, Issue: 5, Pages: 997-
Abstract
This study investigated the impact of different verificationarea designs on the sensitive areas identified using the conditional nonlinear optimal perturbation CNOP method for tropical cyclone targeted observations The sensitive areas identified using the first singular vector FSV method which is the linear approximation of CNOP were also investigated for comparison By analyzing the validity of the sensitive areas the proper design of a verification area was developedTropical cyclone Rananim which occurred in August 2004 in the northwest Pacific Ocean was studied Two sets of verification areas were designed one changed position and the other changed both size and position The CNOP and its identified sensitive areas were found to be less sensitive to small variations of the verification areas than those of the FSV and its sensitive areas With larger variations of the verification area the CNOP and the FSV as well as their identified sensitive areas changed substantially In terms of reducing forecast errors in the verification area the CNOPidentified sensitive areas were more beneficial than those identified using FSV The design of the verification area is important for cyclone prediction The verification area should be designed with a proper size according to the possible locations of the cyclone obtained from the ensemble forecast results In addition the development trend of the cyclone analyzed from its dynamic mechanisms was another reference When the general position of the verification area was determined a small variation in size or position had little influence on the results of CNOP
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