Mark A. Hemer

Wind Waves in the Coupled Climate System

The role waves play in modulating interactions between oceans and atmosphere is emphasized. All exchanges (e.g., momentum, energy, heat, mass, radiation fluxes) are influenced by the geometrical and physical characteristics of the ocean surface, which separates the atmospheric and oceanic boundary layers. A qualitative overview of the main relevant surface gravity wave–driven processes at the air–sea interface that may have an important role in the coupled climate system in general and the atmospheric and oceanic boundary layers in particular is provided.

Quantifying upper ocean turbulence driven by surface waves

[1]xa0Nearly all operational ocean models use air-sea fluxes and the ocean shear and stratification to estimate upper ocean boundary layer mixing rates. This approach implicitly parameterizes surface wave effects in terms of these inputs. Here we test this assumption using parallel experiments in a lake with small waves and in the open ocean with much bigger waves. Under the same wind stress and adjusting for buoyancy flux, we find the mixed layer average turbulent vertical kinetic energy in the open ocean typically twice that in the lake. The increase is consistent with models of Langmuir turbulence, in which the wave Stokes drift, and not wave breaking, is the dominant mechanism by which waves energize turbulence in the mixed layer. Applying these same theories globally, we find enhanced mixing and deeper mixed layers resulting from the inclusion of Langmuir turbulence in the boundary layer parameterization, especially in the Southern Ocean.

Dominant seismic noise sources in the Southern Ocean and West Pacific, 2000–2012, recorded at the Warramunga Seismic Array, Australia

Seismic noise is important in determining Earth structure and also provides an insight into ocean nwave patterns and long-term trends in storm activity and global climate. We present a long-duration study nof seismic noise focused on the Southern Ocean using recordings from the Warramunga Seismic Array, nNorthern Territory, Australia. Using high-resolution analysis, we determine the seismic slowness and back nazimuth of observed seismic noise, microseisms, at hourly intervals through over a decade (2000–2012). nWe identify three dominant sources of body wave ( P ) noise in the Southern Ocean which we interpret to noriginate from a South Atlantic source propagating as PP waves, and Kerguelen Island and Philippine Sea nsources propagating as P waves. We also identify surface waves from around the Australian coast. All sources nshow distinct seasonality and a low, but discernable, interannual variability.