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Kinetic Energy Study of Hurricane Celia, 1970

1974; American Meteorological Society; Volume: 102; Issue: 1 Linguagem: Inglês

10.1175/1520-0493(1974)102 2.0.co;2

1520-0493

Dayton G. Vincent, William Gommel, Long Nan Chang,

Coastal wetland ecosystem dynamics

A diagnostic kinetic energy study of Hurricane Celia, 1970, based on surface and rawinsonde data up to 100 mb, is performed as the storm moves across southern Texas and southwestern New Mexico. A kinetic energy budget is computed for the region bounded by latitudes 37N, 25N and longitudes 110W, 94W (2×1012 m2) for two consecutive 12-hr periods beginning 0000 GMT 4 August and a subsequent 24-hr period from 0000 GMT, 5 August to 0000 GMT, 6 August. This region contains Celia during her 48-hr continental life history. Additional energy computations are performed at 0000 GMT, 4, 5 and 6 August and at 1200 GMT, 4 August for each of three approximately equal smaller regions (5×1011 m2) which essentially isolate the storm's circulation at these times. The most significant results show that (1) energy parameters computed for small regions, particularly during Celia's mature stage (0000–1200 GMT 4 August), are considerably greater than those for the large region, indicating the importance of proper boundary selections in case studies involving synoptic scale systems; (2) kinetic energy is maximum near 500 mb in the eastern sector of the storm at all times; (3) synoptic scale vertical velocities reach a maximum between 500 mb and 300 mb, with peak upward motion of about 10 μbar sec−1 near the storm center on 4 August and concurrent downward motion of slightly lesser intensity surrounding the storm in all quadrants; (4) kinetic energy remains nearly constant during the first twelve hours, decreasing rapidly thereafter; (5) kinetic energy generation (−VċpΦ) is the dominant source term having a maximum value of 20 W m−2 in the smaller region at 0000 and 1200 GMT, 4 August; (6) horizontal boundary fluxes are generally small compared to energy generation; there is, however, an apparent reversal from import to export of energy between the mature and dissipating storm stages; (7) kinetic energy dissipation, calculated as a residual in budget computations for the large region, is about 4 W m−2 during the first twelve hours, 5 W m−2 during the next twelve hours, but a small generation is evident for the final 24 hr. The results strongly suggest that storm systems such as tropical and extratropical cyclones should be investigated, using moving coordinates following the system, by methods similar to those presented by Johnson (1970) or Vincent and Chang (1973).