For more information, contact
Il-Ju Moon
, I. Ginis
, Tetsu Hara
Related Papers
1. Moon, I.-J., I. Ginis, T. Hara, H. Tolman, C.W. Wright, and E.J. Walsh,
2003: Numerical simulation of sea-surface directional wave spectra under hurricane
wind forcing. J. of Phys. Oceanogr., 33, 1680-1706.[
PDF download: 2.6MB
]
2. Moon, I.-J., T. Hara, I. Ginis, and S. E. Belcher, 2003: Effect of surface
waves on air-sea momentum flux: I. Effect of mature and growing sea. J.
Atmos. Science, under review. [
PDF download : 0.7MB
]
3. Moon, I.-J., I. Ginis, and T. Hara, 2003: Effect of surface waves on
air-sea momentum flux: II. Behavior of drag coefficient under tropical cyclone.
J. Atmos. Science, under review. [
PDF download: 3.3MB
]
Background
Surface gravity waves between the atmosphere and the
ocean have a significant impact on the transfer of momentum and energy fluxes
at the air-sea interface (Geernaert, 1990). Conventionally, in tropical-cyclone
modeling the effect of ocean waves on flux transfer at the air-sea interface
is taken into account by using an average roughness length that is linked
to the the surface stress through the Charnock relation (Charnock,1955).
Recently, both observations and numerical modeling dtudies indicated that
the surface stress is a function not only of the wind speed and atmospheric
stability, but also of sea states i.e. the wave spectrum. This implies that
the conventional stress leads to significant errors in the air-sea momentum
flux estimate under storm condition, where wind forcing varies in small spatial
and temporal scales and the wave field is generally not in equilibrium with
the local wind. Our goals of this study are to produce better formulation
of surface flux under storm condition. These formulations will be impemented
in numerical weather prediction models to improve the accuracy of tropical
cyclone intensity prediction.
Estimates of the effect of waves on air-sea momentum exchange
In order to estimate the effect of waves on air-sea
momentum exchange, a ocean-wave model,WAVEWATCH-III, is used for the present
study.The
WAVEWATCH III
(Tolman 1997, 1999a) is an ocean surface wave model developed at NOAA/NCEP
in the spirit of the WAM model (WAMDIG 1988, Komen et al. 1994). WAVEWATCH-III
has characteristics of a third generation approach to wave growth and decay,
explicitly accounting for wind input, wave-wave interaction and dissipation
due to whitecapping and wave-bottom interaction. It furthermore incorporates
effects of unsteady and inhomogeneous currents on ocean waves. This model
is distributed to be public domain and used as
the operational wave models
and the experimental
hurricane wave models
of NOAA/NCEP. This model will be applyed to the experiment of tropical
cyclone intensity prediction in Atlantic region.
Prelimminary Results for Hurricane
Bonnie (1998)
