ICON-waves: towards an atmosphere-waves coupled

2021 ◽  
Author(s):  
Mikhail Dobrynin ◽  
Daniel Reinert ◽  
Florian Prill ◽  
Günther Zängl ◽  
Oliver Sievers ◽  
...  

<p>Wind-driven ocean gravity surface waves affect basic physical processes such as heat, momentum, and mass exchange between the ocean and the atmosphere. Wind wave energy generates additional turbulence, modifies ocean currents, and controls the state of the sea surface. As of now, DWD's operational weather forecast system ICON-NWP does not explicitly account for ocean surface waves. Wave effects, for example, the effect on sea surface roughness, are represented by parameterisations based on local wind speed. However, the physics of the ocean-atmosphere interaction is more complex, and therefore methods of wave-spectrum-based coupling of atmosphere and ocean are necessary and have the potential for improving both weather and wave forecasts. To this end, in the framework of the Innovation Programme for Applied Research and Developments (IAFE) funded by the DWD, a new coupled ICON-NWP-waves system is currently under development. This project aims at using ICON's dynamical core and the wave spectrum physics from the wave model WAM, and will combine both into the new ICON-waves model. A parameterisation of sea surface roughness based on the wave spectrum will provide a two-way coupling mechanism at the ocean-atmosphere interface. The concept of ICON-waves, the current status of development as well as some preliminary results will be presented.<span class="Apple-converted-space"> </span></p>

In this paper we develop a two-scale model of sea-surface roughness, in which for the first time the randomness of both long and short waves is taken fully into account. The model includes long–wave-short-wave interactions, dissipation of the short-wave energy by breaking, and regeneration by the wind. This leads to an integral equation for the short-wave steepness, which is solved by iteration. The effects of wind speed and of long-wave steepness upon the distribution of roughness at the long-wave crests are calculated and discussed. Also the effect of a band-width parameter for the long-wave spectrum. A random noise source can be included.


2021 ◽  
Vol 9 (3) ◽  
pp. 246
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Xiaoyong Li ◽  
Kaijun Ren ◽  
Hongze Leng

A wave state related sea surface roughness parameterization scheme that takes into account the impact of sea foam is proposed in this study. Using eight observational datasets, the performances of two most widely used wave state related parameterizations are examined under various wave conditions. Based on the different performances of two wave state related parameterizations under different wave state, and by introducing the effect of sea foam, a new sea surface roughness parameterization suitable for low to extreme wind conditions is proposed. The behaviors of drag coefficient predicted by the proposed parameterization match the field and laboratory measurements well. It is shown that the drag coefficient increases with the increasing wind speed under low and moderate wind speed conditions, and then decreases with increasing wind speed, due to the effect of sea foam under high wind speed conditions. The maximum values of the drag coefficient are reached when the 10 m wind speeds are in the range of 30–35 m/s.


Author(s):  
Lianxin Zhang ◽  
Xuefeng Zhang ◽  
William Perrie ◽  
Changlong Guan ◽  
Bo Dan ◽  
...  

AbstractA coupled ocean-wave-sea spray model system is used to investigate the impacts of sea spray and sea surface roughness on the response of the upper ocean to the passage of the super typhoon Haitang. Sea spray mediated heat and momentum fluxes are derived from an improved version of Fairall’s heat fluxes formulation (Zhang et al., 2017) and Andreas’s sea spray-mediated momentum flux models. For winds ranging from low to extremely high speeds, a new parameterization scheme for the sea surface roughness is developed, in which the effects of wave state and sea spray are introduced. In this formulation, the drag coefficient has minimal values over the right quadrant of the typhoon track, along which the typhoon-generated waves are longer, smoother, and older, compared to other quadrants. Using traditional interfacial air-sea turbulent (sensible, latent, and momentum) fluxes, the sea surface cooling response to typhoon Haitang is overestimated by 1 °C, which can be compensated by the effects of sea spray and ocean waves on the right side of the storm. Inclusion of sea spray-mediated turbulent fluxes and sea surface roughness, modulated by ocean waves, gives enhanced cooling along the left edges of the cooling area by 0.2 °C, consistent with the upper ocean temperature observations.


2005 ◽  
Author(s):  
G.D. Sandlin ◽  
L.A. Rose ◽  
G.L. Geernaert ◽  
J.P. Hollinger ◽  
F.A. Hansen

2020 ◽  
Vol 125 (8) ◽  
Author(s):  
Nicolas Rascle ◽  
Bertrand Chapron ◽  
Jeroen Molemaker ◽  
Frédéric Nouguier ◽  
Francisco J. Ocampo‐Torres ◽  
...  

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