Wave-Coherent Air–Sea Heat Flux

Abstract

Air-sea fluxes of heat and momentum play a crucial role in weather, climate, and the coupled general circulation of the oceans and atmosphere. Much progress has been made to quantify momentum transfer from the atmosphere to the ocean for a wide range of wind and wave conditions. Yet, despite the fact that global heat budgets are now at the forefront of current research in atmospheric, oceanographic, and climate problems and despite the good research progress in recent years, much remains to be done to better understand and quantify air-sea heat transfer. It is well known that ocean-surface waves may support momentum transfer from the atmosphere to the ocean, but the role of the waves in heat transfer has been ambiguous and poorly understood. Here, evidence is presented that there are surface wave-coherent components of both the sensible and the latent heat fluxes. Presented here are data from three field experiments that show modulations of temperature and humidity at the surface and at 10-14 m above the surface, which are coherent with the surface wave field. The authors show that the phase relationship between temperature and surface displacement is a function of wind speed. At a 10-12-m elevation, a wave-coherent heat transfer of O(1) W m Ϫ2 is found, dominated by the latent heat transfer, as well as wave-coherent fractional contributions to the total heat flux (the sum of latent and sensible heat fluxes) of up to 7%. For the wind speeds and wave conditions of these experiments, which encompass the range of global averages, this wave contribution to total heat flux is comparable in magnitude to the atmospheric heat fluxes commonly attributed to the effects of greenhouse gases or aerosols. By analogy with momentum transfer, the authors expect the wave-coherent heat transfer to decay with height over scales on the order of k Ϫ1 , where k is the characteristic surface wavenumber; therefore, it is also expected that measurements at elevations of O(10) m may underestimate the contribution of the wave-induced heat flux to the atmosphere.

Sea surface microlayer in a changing ocean – A perspective

“…In addition to the stress from the viscous boundary effects and turbulence, there is also stress due to the form of the waves (e.g., Janssen, 1989;Belcher and Hunt, 1993;Makin et al, 1995;Hare et al, 1997;Edson and Fairall, 1998). Recent work (Veron et al, 2008) at low to moderate wind speeds has also shown that that there are wave-modulated sensible and latent heat fluxes. In the marine atmospheric boundary layer, the partition between viscous, turbulent, and wave stresses, is poorly understood.…”

Capillary effects on wave breaking

“…The understanding of dissipation induced by breaking waves at various scales has been the topic of intensive research in recent decades, combining field work in the open ocean (Melville 1996;Melville & Matusov 2002;Veron et al 2008;Sutherland & Melville 2013), laboratory experiments on wave breaking (Melville & Rapp 1985;Tulin & Waseda 1999;Rapp & Melville 1990;Banner & Peirson 2007;Drazen et al 2008), and the dissipation induced by smaller scales involving surface tension, like micro-breaking, spilling breaking (Duncan et al 1999;Duncan 2001;Liu & Duncan 2003, 2006 and parasitic capillary waves (Perlin et al 1993;Jiang et al 1999;Caulliez et al 1998;Su 1982;Caulliez 2013). The importance of small scales, O(1 − 10) cm in the global ocean wave energy fluxes is still an open question and needs further investigation.…”

Airflow measurements at a wavy air–water interface using PIV and LIF

“…(Lumley and Terray 1983;Thais and Magnaudet 1996;Hristov et al 1998;Veron et al 2008;Grare et al 2013a). This is in part due to the technical difficulty associated with making measurements close to the air water interface in the laboratory or the field, and the difficulty in modeling the complex non-linear interactions between the turbulence and the surface waves.…”