Field characterization of wave‐induced underwater light field fluctuations

Abstract

[1] A field characterization of the amplitude and periods of the underwater light field fluctuations is presented on the basis of field measurements of the downward and upward irradiances at a deep-sea mooring in the Mediterranean Sea (BOUSSOLE site). The optical time series at this site includes multispectral irradiance measurements at two depths and irradiance profiles taken from free-fall radiometers. It is already several years long and is paralleled by a time series of wind and waves. When pooled together, both data sets provide an opportunity to complement previous field experiments dedicated to the understanding of underwater light fluctuations, which were mostly carried out in coastal waters and essentially for the downward irradiance, by exploring more systematically the electromagnetic spectrum and the range of environmental parameters. In addition, the characteristics of the upward flux are also investigated. The behavior of the amplitude and period of the

On the influence of wind and waves on underwater irradiance fluctuations

“…By means of our model, we have demonstrated that more developed gravity waves -here one can speak of a sea state -primarily affect deeper water layers, but essentially not the upper most 10 m. This statement is confirmed by Gernez and Antoine (2009), who showed that gravity waves have no evident impact on irradiance fluctuations at approximately 4 m depth and that the wave height has relatively little influence on CV and the spectral peak period of fluctuations. Our earlier measuring campaigns suggested that below 5 m depth, light fluctuations can be described more accurately in terms of wave height and period, rather than wind speed, and that between 3 and 25 m water depth waves with H s of 1.5 to 2.5 m provoke the strongest intensity fluctuations (Hieronymi and Macke, 2010).…”

“…Nikolayev et al, 1972;Dera and Stramski, 1986;Gernez and Antoine, 2009;Weber, 2010;Hieronymi and Macke, 2010;Darecki et al, 2011). There is general agreement that the most favorable conditions for light focusing by waves prevail at moderate winds between 2 and 7 m s −1 .…”

“…They are selected in such a manner that maximum light fluctuations can be achieved (Dera and Stramski, 1986;Walker, Gernez and Antoine, 2009;Darecki et al, 2011;Gege and Pinnel, 2011). However, orange-red light (580-700 nm) is strongly attenuated by absorption in water (e.g.…”

“…Stramski, 1986;Walker, 1994;Stramska and Dickey, 1998;Gernez and Antoine, 2009;Gege and Pinnel, 2011). Compared to other natural light regimes (e.g.…”

“…There are several papers on the relationship between wind conditions and underwater light field fluctuations (e.g. Nikolayev et al, 1972;Dera and Stramski, 1986;Gernez and Antoine, 2009;Weber, 2010;Hieronymi and Macke, 2010;Darecki et al, 2011). The general view is that the most favorable conditions for light…”