Azimuthal and Radial Variation of Wind-Generated Surface Waves inside Tropical Cyclones

AbstractFor wind-generated waves, the wind-wave triplets (reference wind speed, significant wave height, and spectral peak wave period) are intimately connected through the fetch- or duration-limited wave growth functions. The full set of the triplets can be obtained knowing only one of the three, together with the input of fetch (duration) information using the pair of fetch-limited (duration limited) wave growth functions. The air–sea energy and momentum exchanges are functions of the wind-wave triplets, and they can be quantified with the wind-wave growth functions. Previous studies have shown that the wave development inside hurricanes follows essentially the same growth functions established for steady wind forcing conditions. This paper presents the analysis of wind-wave triplets collected inside Hurricane Bonnie 1998 at category 2 stage along 10 transects radiating from the hurricane center. A fetch model is formulated for any location inside the hurricane. Applying the fetch model to the 2D hurricane wind field, the detailed spatial distribution of the wave field and the associated energy and momentum exchanges inside the hurricane are investigated. For the case studied, the energy and momentum exchanges display two local maxima resulting from different weightings of wave age and wind speed. Referenced to the hurricane heading, the exchanges on the right half plane of the hurricane are much stronger than those on the left half plane. Integrated over the hurricane coverage area, the right-to-left ratio is about 3:1 for both energy and momentum exchanges. Computed exchange rates with and without considering wave properties differ significantly.

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Effective Fetch and Duration of Tropical Cyclone Wind Fields Estimated from Simultaneous Wind and Wave Measurements: Surface Wave and Air–Sea Exchange Computation

Journal of Physical Oceanography ◽

10.1175/jpo-d-16-0180.1 ◽

2017 ◽

Vol 47 (2) ◽

pp. 447-470 ◽

Cited By ~ 23

Author(s):

Paul A. Hwang ◽

Yalin Fan

Keyword(s):

Surface Wave ◽

Wind Field ◽

Wind Wave ◽

Environmental Parameters ◽

Wind Fields ◽

Growth Functions ◽

Wave Measurements ◽

Hurricane Wind ◽

Wave Development ◽

Energy And Momentum

AbstractSimultaneous wind and wave measurements have been obtained inside tropical cyclones in several hurricane hunter missions. Analyses of these datasets show that the surface wave development inside hurricanes follows essentially the same duration- and fetch-limited growth functions established in steady wind forcing conditions. This paper explores the application of several parameterization functions of wind-wave systems to quantify the energy and momentum exchanges inside hurricanes from an initially limited input of the environmental parameters, such as the wind field alone. A critical prerequisite to applying the wind-wave growth functions is the knowledge of fetch and duration for the hurricane wind field. Four sets of simultaneous wind and wave measurements from hurricane hunter missions are analyzed to derive a fetch and duration scaling model. Time series of 2D hurricane wind fields can then be used to investigate the detailed spatial distribution and temporal evolution of the sea state parameters and the associated air–sea energy and momentum exchanges following the hurricane development.

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Fetch-limited surface wave growth inside tropical cyclones and hurricane wind speed retrieval

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) ◽

10.1109/igarss.2016.7729569 ◽

2016 ◽

Cited By ~ 1

Author(s):

Paul A. Hwang ◽

Xiaofeng Li ◽

Biao Zhang ◽

Edward J. Walsh

Keyword(s):

Surface Wave ◽

Wind Speed ◽

Tropical Cyclones ◽

Wave Growth ◽

Hurricane Wind ◽

Limited Surface

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Research on Wind Wave Considering Nonlinear Dispersion Effect

Volume 5: Ocean Engineering ◽

10.1115/omae2013-11511 ◽

2013 ◽

Author(s):

Xiejun Shu ◽

Peng Hou ◽

Hua Zhuang ◽

Mingli Zhao

Keyword(s):

Wind Speed ◽

Wind Wave ◽

Order Term ◽

Offshore Wind ◽

Nonlinear Dispersion ◽

Dispersion Effect ◽

Linear Dispersion ◽

Offshore Area ◽

Wave Growth ◽

Open Sea

Understanding of the offshore wind wave status plays a guiding role in surrounding marine engineering constructions, marine traffic, sea farming, etc. Further study is beneficial to marine economy development, as well as to the academic value of wave theory. This paper primarily introduces the deduction of new wind wave growth relations. Firstly, a new relation formula between wave steepness and wave age was deduced by combining the 3/2 power law developed by Toba with the nonlinear dispersion relation deduced by Li, and by ignoring the effect of water depth. And when the higher-order term was ignored, the relation formula can be simplified as that based on linear dispersion. Secondly, based on the combination of this new relation formula with the significant wave energy balance equation, new wind wave growth relation formulae including the wave non-linear dispersion effect were deduced. When the deduced growth relation formulae were applied in offshore area of Jiangsu incorporating with Mitsuyasu’s empirical formula about the open sea fetch and wind speed, accurate open sea wave parameters of Jiangsu can be formulated by only considering one parameter, such as wind speed. Overall, as this methodology avoided the uncertainty about the fetch of open ocean and operation error during the calculation process, results gained from this report had higher accuracy than other published formulae, and results were validated by NCEP reanalyzing data of Jiangsu offshore area and other researches.

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Fetch- and Duration-Limited Nature of Surface Wave Growth inside Tropical Cyclones: With Applications to Air–Sea Exchange and Remote Sensing

Journal of Physical Oceanography ◽

10.1175/jpo-d-15-0173.1 ◽

2016 ◽

Vol 46 (1) ◽

pp. 41-56 ◽

Cited By ~ 33

Author(s):

Paul A. Hwang

Keyword(s):

Field Experiments ◽

Wind Wave ◽

Growth Curves ◽

Dimensionless Frequency ◽

Radar Altimeter ◽

Coverage Area ◽

Wave Growth ◽

Left Hand ◽

Dominant Wave ◽

Eye Region

AbstractThe 2D wavenumber spectra collected by an airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch- and duration-limited nature of wave growth inside hurricanes. Despite the much more complex wind-forcing conditions, the dimensionless growth curves obtained with the wind-wave triplets (reference wind velocity, significant wave height, and dominant wave period) inside hurricanes, except near the eye region, are comparable to the reference similarity counterparts constructed with the wind-wave triplets collected in field experiments conducted under ideal quasi-steady fetch-limited conditions. In dimensionless terms, the youngest waves are in the back quarter of the hurricane. In the Northern Hemisphere, the dimensionless frequency decreases systematically counterclockwise (CCW), and the most mature waves are in the left-hand sector. Except for those waves near the eye region, the dominant wave phase speeds are about 0.32 to 0.71 times of the local wind speed, and they are proper wind seas. Based on the computation of the wind input or energy dissipation in the wave field, a conservative estimate of the air–sea energy exchange over the coverage area of a category one hurricane is about 5 TW. Formulas for the effective fetches and durations in the three hurricane sectors are derived from the data. Using these formulas together with the wave growth functions, the full set of wind-wave triplets can be calculated knowing only one of the three. These results may enhance the capability and scope of monitoring hurricanes from space.

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WAVE CLIMATE OF THE BLACK SEA’S COASTAL WATERS DURING THE LAST THREE DECADES

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b943584ab71.87772537 ◽

2017 ◽

Author(s):

Fedor Gippius ◽

Stanislav Myslenkov ◽

Elena Stoliarova ◽

...

Keyword(s):

Wind Speed ◽

Cell Size ◽

Coastal Waters ◽

Wind Wave ◽

Spatial Scales ◽

Wave Model ◽

Wave Climate ◽

Computational Grid ◽

Coastal Areas ◽

Wave Parameters

This study is focused on the alterations and typical features of the wind wave climate of the Black Sea’s coastal waters since 1979 till nowadays. Wind wave parameters were calculated by means of the 3rd-generation numerical spectral wind wave model SWAN, which is widely used on various spatial scales – both coastal waters and open seas. Data on wind speed and direction from the NCEP CFSR reanalysis were used as forcing. The computations were performed on an unstructured computational grid with cell size depending on the distance from the shoreline. Modeling results were applied to evaluate the main characteristics of the wind wave in various coastal areas of the sea.

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A Functional Data Analysis Approach to Registering and Identifying Trends of Gulf Hurricane Wind Speed

SSRN Electronic Journal ◽

10.2139/ssrn.3695432 ◽

2020 ◽

Author(s):

Austin Workman

Keyword(s):

Data Analysis ◽

Wind Speed ◽

Functional Data Analysis ◽

Functional Data ◽

Analysis Approach ◽

Hurricane Wind

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On the Lyapunov design of systems with zeros in the right-half plane

IEEE Transactions on Automatic Control ◽

10.1109/tac.1970.1099388 ◽

1970 ◽

Vol 15 (1) ◽

pp. 139-140 ◽

Cited By ~ 1

Author(s):

H. Kang ◽

A. Mahalanabis

Keyword(s):

Half Plane ◽

Lyapunov Design ◽

The Right

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Topographic Speed-Up Effects and Observed Roof Damage on Bermuda following Hurricane Fabian (2003)

Weather and Forecasting ◽

10.1175/waf-d-12-00050.1 ◽

2013 ◽

Vol 28 (1) ◽

pp. 159-174 ◽

Cited By ~ 13

Author(s):

Craig Miller ◽

Michael Gibbons ◽

Kyle Beatty ◽

Auguste Boissonnade

Keyword(s):

Surface Roughness ◽

Wind Speed ◽

Surface Wind ◽

Open Water ◽

Clear Trend ◽

Wind Speeds ◽

Research Division ◽

Hurricane Wind ◽

Layer Flow ◽

Observed Damage

Abstract In this study the impacts of the topography of Bermuda on the damage patterns observed following the passage of Hurricane Fabian over the island on 5 September 2003 are considered. Using a linearized model of atmospheric boundary layer flow over low-slope topography that also incorporates a model for changes of surface roughness, sets of directionally dependent wind speed adjustment factors were calculated for the island of Bermuda. These factors were then used in combination with a time-stepping model for the open water wind field of Hurricane Fabian derived from the Hurricane Research Division Real-Time Hurricane Wind Analysis System (H*Wind) surface wind analyses to calculate the maximum 1-min mean wind speed at locations across the island for the following conditions: open water, roughness changes only, and topography and roughness changes combined. Comparison of the modeled 1-min mean wind speeds and directions with observations from a site on the southeast coast of Bermuda showed good agreement between the two sets of values. Maximum open water wind speeds across the entire island showed very little variation and were of category 2 strength on the Saffir–Simpson scale. While the effects of surface roughness changes on the modeled wind speeds showed very little correlation with the observed damage, the effect of the underlying topography led to maximum modeled wind speeds of category 4 strength being reached in highly localized areas on the island. Furthermore, the observed damage was found to be very well correlated with these regions of topographically enhanced wind speeds, with a very clear trend of increasing damage with increasing wind speeds.

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Observed Boundary Layer Wind Structure and Balance in the Hurricane Core. Part I: Hurricane Georges

Journal of the Atmospheric Sciences ◽

10.1175/jas3745.1 ◽

2006 ◽

Vol 63 (9) ◽

pp. 2169-2193 ◽

Cited By ~ 101

Author(s):

Jeffrey D. Kepert

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Tropical Cyclone ◽

Radial Profile ◽

Lower Altitude ◽

Near Surface ◽

Wind Structure ◽

The Right ◽

Tropical Cyclone Boundary Layer ◽

Upper Boundary

Abstract The GPS dropsonde allows observations at unprecedentedly high horizontal and vertical resolution, and of very high accuracy, within the tropical cyclone boundary layer. These data are used to document the boundary layer wind field of the core of Hurricane Georges (1998) when it was close to its maximum intensity. The spatial variability of the boundary layer wind structure is found to agree very well with the theoretical predictions in the works of Kepert and Wang. In particular, the ratio of the near-surface wind speed to that above the boundary layer is found to increase inward toward the radius of maximum winds and to be larger to the left of the track than to the right, while the low-level wind maximum is both more marked and at lower altitude on the left of the storm track than on the right. However, the expected supergradient flow in the upper boundary layer is not found, with the winds being diagnosed as close to gradient balance. The tropical cyclone boundary layer model of Kepert and Wang is used to simulate the boundary layer flow in Hurricane Georges. The simulated wind profiles are in good agreement with the observations, and the asymmetries are well captured. In addition, it is found that the modeled flow in the upper boundary layer at the eyewall is barely supergradient, in contrast to previously studied cases. It is argued that this lack of supergradient flow is a consequence of the particular radial structure in Georges, which had a comparatively slow decrease of wind speed with radius outside the eyewall. This radial profile leads to a relatively weak gradient of inertial stability near the eyewall and a strong gradient at larger radii, and hence the tropical cyclone boundary layer dynamics described by Kepert and Wang can produce only marginally supergradient flow near the radius of maximum winds. The lack of supergradient flow, diagnosed from the observational analysis, is thus attributed to the large-scale structure of this particular storm. A companion paper presents a similar analysis for Hurricane Mitch (1998), with contrasting results.

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