Influence of natural surfactants on short wind waves in the coastal Peruvian waters
D. Kiefhaber1,2, C. J. Zappa3, and B. Jähne1,21Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany 2Heidelberg Collaboratory for Image Processing (HCI) at the Interdisciplinary Center for Scientific Computation, University of Heidelberg, Speyerer Str. 6, 69115 Heidelberg, Germany 3Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades 10964, NY, USA
Received: 31 May 2015 – Accepted for review: 02 Jun 2015 – Discussion started: 03 Jul 2015
Abstract. Results from measurements of wave slope statistics during the R/V Meteor M91 cruise in the coastal upwelling regions off the coast of Peru are reported. Wave slope probability distributions were measured with an instrument based on the reflection of light at the water surface and a method very similar to the Cox and Munk (1954b) sun glitter technique. During the cruise, the mean square slope (mss) of the waves was found to be very variable, despite the limited range of encountered wind speeds. The Cox and Munk (1954b) parameterization for clean water is found to overestimate mss, but most measurements fall in the range spanned by their clean water and slick parameterizations. The observed variability of mss is attributed to the wave damping effect of surface films, generated by increased biological production in the upwelling zones. The small footprint and high temporal resolution of the measurement allows for tracking abrupt changes in conditions caused by the often patchy structure of the surface films.
Kiefhaber, D., Zappa, C. J., and Jähne, B.: Influence of natural surfactants on short wind waves in the coastal Peruvian waters, Ocean Sci. Discuss., 12, 1291-1325, doi:10.5194/osd-12-1291-2015, 2015.