The delicate balance of the nearshore environment is important for native fauna as well as economic activity. Temperature variations in the nearshore environment, including the surf zone and inner shelf, are especially important. For example, fluctuations can affect mussel and barnacle growth rates and coastal crab egg production. Water temperature is also crucial to the growth of harmful bacteria that could limit surf zone recreational use.
Sinnett and Feddersen conducted a study of water temperature in nearshore environments to determine how much wave energy flux contributes to the surf zone heat budget. Prior to this study, the main drivers for water temperature in the surf zone were unknown.
Heat is generated through viscous dissipation when waves break in the surf zone. Cooling results from internal waves, rip currents, and undertow. The surf zone heat budget combines these factors and others to determine the net daily heating or cooling of ocean water and over longer time periods.
The team observed the nearshore water temperature at the Scripps Institute of Oceanography pier in La Jolla, Calif., for 47 days in June and July 2013. They inserted thermistors at set points in the surf zone and along the inner shelf to measure the water temperature at 0.9 meters below sea level. They also collected meteorological measurements, tidal elevations, and wave data.
The authors concluded that short-wave solar radiation was the largest driver of temperature in the surf zone heat budget for diurnal and longer time periods. Wave energy flux contributed to surf zone heating at a rate one quarter of that of solar radiation and was the second-largest driver of temperature changes. (Geophysical Research Letters, doi:10.1002/2014GL061398, 2014)
—Catherine Minnehan, Freelance Writer
Citation: Minnehan, C. (2015), Wave energy affects the surf zone heat budget, Eos, 96, doi:10.1029/2015EO023167. Published on 5 February 2015.