Impacts of Momentum Fluxes Modulated by Surface Waves on Near‐Inertial Motions in Tropical Cyclones

2021 ◽  
Author(s):  
Lei Zhang ◽  
Guoqiang Liu ◽  
Yijun He ◽  
William Perrie
Keyword(s):  
Surface Waves ◽  
Tropical Cyclones ◽  
Momentum Fluxes

scholarly journals A Review of Parameterizations for Enthalpy and Momentum Fluxes from Sea Spray in Tropical Cyclones

2021 ◽  
Author(s):  
Sydney Sroka ◽  
Kerry Emanuel
Keyword(s):  
Tropical Cyclones ◽  
Critical Role ◽  
Sea Spray ◽  
High Wind ◽  
High Wind Speed ◽  
Wind Speeds ◽  
Crucial Component ◽  
Momentum Fluxes ◽  
Interaction Scheme ◽  
Speed Regime

AbstractThe intensity of tropical cyclones is sensitive to the air-sea fluxes of enthalpy and momentum. Sea spray plays a critical role in mediating enthalpy and momentum fluxes over the ocean’s surface at high wind speeds, and parameterizing the influence of sea spray is a crucial component of any air-sea interaction scheme used for the high wind regime where sea spray is ubiquitous. Many studies have proposed parameterizations of air-sea flux that incorporate the microphysics of sea spray evaporation and the mechanics of sea spray stress. Unfortunately, there is not yet a consensus on which parameterization best represents air-sea exchange in tropical cyclones, and the different proposed parameterizations can yield substantially different tropical cyclone intensities. This paper seeks to review the developments in parameterizations of the sea spray-mediated enthalpy and momentum fluxes for the high wind speed regime and to synthesize key findings that are common across many investigations.

scholarly journals Wave Glider Observations of Surface Waves During Three Tropical Cyclones in the South China Sea

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1331 ◽  
Author(s):  
Di Tian ◽  
Han Zhang ◽  
Wenyan Zhang ◽  
Feng Zhou ◽  
Xiujun Sun ◽  
...  
Keyword(s):  
Surface Wave ◽  
South China Sea ◽  
Surface Waves ◽  
Tropical Cyclones ◽  
South China ◽  
Tangential Direction ◽  
China Sea ◽  
Wave Forecast ◽  
Wave Glider ◽  
The Right

Surface waves induced by tropical cyclones (TCs) play an important role in the air–sea interaction, yet are seldom observed. In the 2017 summer, a wave glider in the northern South China Sea successfully acquired the surface wave parameters when three TCs (Hato, Pakhar, and Mawar) passed though successively. During the three TCs, surface wave period increased from 4–6 s to ~8–10 s and surface wave height increased from 0–1 m to 3–8 m. The number of wave crests observed in a time interval of 1024 s decreased from 100–150 to 60–75. The sea surface roughness, a key factor in determining the momentum transfer between air and sea, increased rapidly during Hato, Pakhar, and Mawar. Surface waves rotated clockwise (anti-clockwise) on the right (left) side of the TC track, and generally propagated to the right side of the local cyclonic tangential direction relative to the TC center. The azimuthal dependence of the wave propagation direction is close to sinusoidal in a region within 50–600 km. The intersection angle between surface wave direction and the local cyclonic tangential direction is generally smallest in the right-rear quadrant of the TC and tends to be largest in the left-rear quadrant. This new set of glider wave observational data proves to be useful for assessing wave forecast products and for improvements in corresponding parameterization schemes.

Observed Variability of Ocean Wave Stokes Drift, and the Eulerian Response to Passing Groups

2006 ◽  
Vol 36 (7) ◽  
pp. 1381-1402 ◽  
Author(s):  
Jerome A. Smith
Keyword(s):  
Surface Waves ◽  
Current Theory ◽  
Surface Flow ◽  
Stokes Drift ◽  
Wave Group ◽  
Lagrangian Surface ◽  
Wave Groups ◽  
Wide Range ◽  
Momentum Fluxes ◽  
Waves And Currents

Abstract Waves and currents interact via exchanges of mass and momentum. The mass and momentum fluxes associated with surface waves are closely linked to their Stokes drift. Both the variability of the Stokes drift and the corresponding response of the underlying flow are important in a wide range of contexts. Three methods are developed and implemented to evaluate Stokes drift from a recently gathered oceanic dataset, involving surface velocities measured continually over an area 1.5 km in radius by 45°. The estimated Stokes drift varies significantly, in line with the occurrence of compact wave groups, resulting in highly intermittent maxima. One method also provides currents at a fixed level (Eulerian velocities). It is found that Eulerian counterflows occur that completely cancel the Stokes drift variations at the surface. Thus, the estimated Lagrangian surface flow has no discernable mean response to wave group passage. This response is larger than anticipated and is hard to reconcile with current theory.

scholarly journals Surface Wave Effects on the Wind-Power Input to Mixed Layer Near-Inertial Motions

2017 ◽  
Vol 47 (5) ◽  
pp. 1077-1093 ◽  
Author(s):  
Guoqiang Liu ◽  
William Perrie ◽  
Colin Hughes
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Wind Power ◽  
Mixed Layer ◽  
Single Point ◽  
Storm Track ◽  
Power Input ◽  
Momentum Fluxes ◽  
Wave Effects ◽  
Evolving Surface

AbstractOcean surface waves play an essential role in a number of processes that modulate the momentum fluxes through the air–sea interface. In this study, the effects of evolving surface waves on the wind-power input (WPI) to near-inertial motions (NIMs) are examined by using momentum fluxes from a spectral wave model and a simple slab ocean mixed layer model. Single-point numerical experiments show that, without waves, the WPI and the near-inertial kinetic energy (NI-KE) are overestimated by about 20% and 40%, respectively. Globally, the overestimate in WPI is about 10% during 2005–08. The largest surface wave effects occur in the winter storm-track regions in the midlatitude northwestern Atlantic, Pacific, and in the Southern Ocean, corresponding to large inverse wave age and rapidly varying strong winds. A relatively low frequency of occurrence of wind sea is found in the midlatitudes, which implies that the influence of evolving surface waves on WPI is intermittent, occurring less than 10% of the total time but making up the dominant contributions to reductions in WPI. Given the vital role of NIMs in diapycnal mixing at the base of the mixed layer and the deep ocean, the present study suggests that it is necessary to include the effects of surface waves on the momentum flux, for example, in studies of coupled ocean–atmosphere dynamics or climate models.

scholarly journals Young Ocean Waves Favor the Rapid Intensification of Tropical Cyclones—A Global Observational Analysis

2018 ◽  
Vol 147 (1) ◽  
pp. 311-328 ◽  
Author(s):  
Lin Zhang ◽  
Leo Oey
Keyword(s):  
Tropical Cyclone ◽  
Surface Waves ◽  
Tropical Cyclones ◽  
Ocean Waves ◽  
Surface Fluxes ◽  
Moisture Convergence ◽  
Intensity Change ◽  
Upper Ocean ◽  
Rapid Intensification ◽  
Low Level

Abstract Identifying the condition(s) of how tropical cyclones intensify, in particular rapid intensification, is challenging, because of the complexity of the problem involving internal dynamics, environments, and mutual interactions; yet the benefit to improved forecasts may be rewarding. To make the analysis more tractable, an attempt is made here focusing near the sea surface, by examining 23-yr global observations comprising over 16 000 cases of tropical cyclone intensity change, together with upper-ocean features, surface waves, and low-level atmospheric moisture convergence. Contrary to the popular misconception, we found no statistically significant evidence that thicker upper-ocean layers and/or warmer temperatures are conducive to rapid intensification. Instead, we found in storms undergoing rapid intensification significantly higher coincidence of low-level moisture convergence and a dimensionless air–sea exchange coefficient closely related to the youth of the surface waves under the storm. This finding is consistent with the previous modeling results, verified here using ensemble experiments, that higher coincidence of moisture and surface fluxes tends to correlate with intensification, through greater precipitation and heat release. The young waves grow to saturation in the right-front quadrant as a result of trapped-wave resonance for a group of Goldilocks cyclones that translate neither too slowly nor too quickly, which 70% of rapidly intensifying storms belong. Young waves in rapidly intensifying storms also produce relatively less (as percentage of the wind input) Stokes-induced mixing and cooling in the cyclone core. A reinforcing coupling between tropical cyclone wind and waves leading to rapid intensification is proposed.

scholarly journals Multilevel Tower Observations of Vertical Eddy Diffusivity and Mixing Length in the Tropical Cyclone Boundary Layer during Landfalls

2018 ◽  
Vol 75 (9) ◽  
pp. 3159-3168 ◽  
Author(s):  
Jie Tang ◽  
Jun A. Zhang ◽  
Sim D. Aberson ◽  
Frank D. Marks ◽  
Xiaotu Lei
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclones ◽  
Numerical Models ◽  
Theoretical Method ◽  
Eddy Diffusivity ◽  
Eddy Correlation ◽  
Mixing Length ◽  
Momentum Fluxes ◽  
Vertical Eddy Diffusivity ◽  
Vertical Eddy

Abstract This study analyzes the fast-response (20 Hz) wind data collected by a multilevel tower during the landfalls of Tropical Storm Lionrock (1006), Typhoon Fanapi (1011), and Typhoon Megi (1015) in 2010. Turbulent momentum fluxes are calculated using the standard eddy-correlation method. Vertical eddy diffusivity Km and mixing length are estimated using the directly measured momentum fluxes and mean-wind profiles. It is found that the momentum flux increases with wind speed at all four levels. The eddy diffusivity calculated using the direct-flux method is compared to that using a theoretical method in which the vertical eddy diffusivity is formulated as a linear function of the friction velocity and height. It is found that below ~60 m, Km can be approximately parameterized using this theoretical method, though this method overestimates Km for higher altitude, indicating that the surface-layer depth is close to 60 m in the tropical cyclones studied here. It is also found that Km at each level varies with wind direction during landfalls: Km estimated based on observations with landward fetch is significantly larger than that estimated using data with seaward fetch. This result suggests that different parameterizations of Km should be used in the boundary layer schemes of numerical models forecasting tropical cyclones over land versus over the ocean.

scholarly journals Simulated ocean response to tropical cyclones: The effect of a novel parameterization of mixing from unbroken surface waves

2017 ◽  
Vol 9 (2) ◽  
pp. 759-780 ◽  
Author(s):  
Lachlan Stoney ◽  
Kevin Walsh ◽  
Alexander V. Babanin ◽  
Malek Ghantous ◽  
Pallavi Govekar ◽  
...  
Keyword(s):  
Surface Waves ◽  
Tropical Cyclones ◽  
Ocean Response
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