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Øyvind Saetra
,
Jon Albretsen
, and
Peter A. E. M. Janssen

condition in both the atmospheric and the ocean models, the net momentum flux is not necessarily conserved. The amount of momentum lost from the atmosphere may be different from the amount of momentum gained by the ocean. A second point is that the surface stress is also, to a large extent, dependent on the sea state, that is, how the wave energy is distributed over the frequency range. A young wind sea is more dominated by waves in the high-frequency part of the spectrum than an old wind sea, whereas

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James Foster
,
Ning Li
, and
Kwok Fai Cheung

1. Introduction Direct measurements of sea state are mostly performed by wave buoys or from sensors attached to fixed structures such as drilling platforms. While buoys provide accurate observations, the high costs for initial installation, and ongoing maintenance and communications have tended to limit their deployment to coastal waters, augmented by a sparse deep-water network ( Fig. 1 ). Global coverage of sea state measurements can be provided by satellite observations (e.g., Gonzalez et

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James A. Mueller
and
Fabrice Veron

1. Introduction Current hurricane models are unable to produce high wind speeds when using traditional air–sea flux parameterizations. Emanuel (1995) showed that the ratio of the enthalpy exchange coefficient to the drag coefficient controls the maximum wind speed and that traditional parameterizations produce too low of a ratio when extrapolated to high wind speeds. Consequently, some combination of a higher enthalpy exchange coefficient and a lower drag coefficient is necessary to simulate

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Xiaohui Zhou
,
Tetsu Hara
,
Isaac Ginis
,
Eric D’Asaro
,
Je-Yuan Hsu
, and
Brandon G. Reichl

. Toba et al. (1990) show that Z ch increases with the wave age if laboratory observations (with very small wave ages) are included. Some studies ( Taylor and Yelland 2001 ; Edson et al. 2013 ) suggest that Z ch increases with wave steepness ( H s / L p , where H s is the significant wave height and L p is the wavelength at the wave spectral peak) in low to medium wind speeds. Under TC conditions the sea state dependence of C d has been addressed in very few observational studies

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R. S. Gibson
,
C. Swan
, and
P. S. Tromans

order to have confidence in the extremes of the distributions, many hours of a particular sea state must be modeled. Many of these limitations can be overcome by using the SRS method. First, by incorporating a suitable wave model into the method, the full nonlinearity can be considered. This task is addressed in the present paper. Second, the sea state can be described by a realistic broadbanded and directionally spread spectrum; the former is addressed herein, and the latter is left for a

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Qiang Wang
,
Yinxia Wang
,
Junpeng Sui
,
Weidong Zhou
, and
Daning Li

Generally, the strength of the SCS winter current is negatively correlated with the SCS upper thermal state ( Fig. 2 ). However, the relationship between them is not stable, especially for moderate strengths of winter SCS currents (STD of KE of WBC between −1 and 1), which have no influence on the SCS upper thermal state. Fig . 2. (a) Relationship between the observed sea surface temperature anomaly (SSTA) and the kinetic energy (KE) anomaly of the SCS western boundary current (WBC). (b) As in (a), but

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Paul A. Hwang
,
Héctor García-Nava
, and
Francisco J. Ocampo-Torres

illustrate the temporal variation. A star indicates the starting condition, a triangle represents the condition at the maximal wind speed that separates the growing and decaying phases of the event, and a circle denotes the end of the event. Because of the mixed-sea condition, the starting state (indicated by the star) may deviate considerably from the more ideal fetch-limited growth curves. As the wind event begins, the wind sea quickly adjusts to the condition similar to that of the ideal fetch

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Guillaume Dodet
,
Saleh Abdalla
,
Matias Alday
,
Mickaël Accensi
,
Jean Bidlot
, and
Fabrice Ardhuin

1. Introduction Historical wave data are important for many scientific and engineering applications (climate science, marine safety, coastal and offshore structures, coastal risk management). The sea state is observed by a variety of instrument networks, including Voluntary Observing Ships, seismometers, moored and drifting buoys, satellite altimeters, and satellite-borne synthetic aperture radars ( Ardhuin et al. 2019 ). In addition, wave model hindcasts and reanalysis provide accurate

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Duncan Cook
and
Sally Garrett

the Horn of Africa was conducted in sea states of 4 and below (94% of paired observations) ( Fig. 7 ), with most of these attacks launched in relatively calm oceans of sea state 3 and below (wave heights < 1.25 m). Attack success steadily declined as wave heights increased, with threshold behavior less conspicuous than that exhibited by the wind speed results ( Fig. 7 ). Fig . 5. Location of pirate attacks (open circles) and matching satellite observations ( n = 155) used in this study. Black

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Paul A. Hwang
and
Yalin Fan

footing because of the advancing wind field and differences in the base sea state from upstream feeding. To account for the observed systematic deviation from the reference growth curves of the hurricane wind waves in different sectors ( Fig. 2 ), the fetches or durations for H s and T p are allowed to be different. The results show that the effective fetch and duration increase about linearly with the distance r to the measurement location from the hurricane center. The slope s and intercept

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