Study of the optimal precursors for blocking events
The precursors of dipole blocking are obtained by a numerical approach based upon a quasi-geostrophic barotropic planetary-to synoptic-scale interaction model without topography and with a localized synopticscale wave-maker. The optimization problem related to the precursors of blocking is formulated and the nonlinear optimization method is used to examine the optimal synoptic-scale initial field successfully. The results show that the prominent characteristics of the optimal synoptic-scale initial field are that the synoptic-scale wave train structures exist upstream of the incipient blocking. In addition, the large-scale low/high eddy-forcing pattern upstream of the incipient blocking is an essential precondition for the onset of dipole blocking.
Key wordsnonlinear optimization method dipole blocking pre-condition eddy-forcing
Unable to display preview. Download preview PDF.
- Duan Wansuo, Mu Mu, and Wang Bin, 2004: Conditional nonlinear optimal perturbations as the optimal precursors for ENSO events.J. Geophys. Res.,109, 4756–4768.Google Scholar
- Jiang Zhina, Luo Dehai, and Diao Yina, 2005: Numerical simulation of interaction between planetary-scale waves and synoptic-scale waves.Journal of Ocean University of China, (in press). (in Chinese)Google Scholar
- Li Zhijin, A. Barcilon, and I. M. Navon, 1999: Study of block onset using sensitivity perturbation in climatological flows.Mon. Wea. Rev.,127(3), 879–900.Google Scholar
- Luo Dehai, 1999:Envelope Rossby Solitions in the Large-Scale Atmosphere and Blocking Circulations. China Meteorological Press, Beijing, 113pp. (in Chinese)Google Scholar
- Mu Mu, 2000: Nonlinear singular vectors and nonlinear singular values.Sciences in China (D),43, 375–385.Google Scholar
- Mu Mu, and Wang Jiacheng, 2001: Nonlinear fastest growing perturbation and the first kind of predictability.Science in China (D),44, 1128–1139.Google Scholar
- Mu Mu, and Duan Wansuo, 2003: A new approach to studying ENSO predictability: Conditional nonlinear optimal perturbation.Chinese Science Bulletin,48, 747–749.Google Scholar
- Mu Mu, Duan Wansuo, and Wang Jiafeng, 2002: Nonlinear optimization problems in atmospheric and oceanic sciences.East-West Journal of Mathematics, Special volume on Computational Mathematics and Modeling,155, 169–178.Google Scholar
- Mu Mu, Duan Wansuo, and Wang Bin, 2003: Conditional nonlinear optimal perturbation and its application.Nonlinear Processes in Geophysics,10, 493–501.Google Scholar
- Rex, D. F., 1950a: Blocking action in the middle troposphere and its effects on regional climate. 1. An aerological study of blocking.Tellus,2, 196–211.Google Scholar
- Shutts, G. J., 1983: The propagation of eddies in diffluent jet streams: Eddy vorticity forcing of blocking flow fields.Quart. J. Roy. Meteor. Soc.,109, 737–761.Google Scholar
- Tibaldi, S., and F. Molteni, 1990: On the operational predictability of blocking.Tellus,42A, 343–365.Google Scholar