Experimental Apparatus A picture of the apparatus is shown in Fig. It is an open, square frame, 1.8 meters on a side, with floatation at each corner, and held together with horizontal stainless steel rods above the surface. The apparatus is flexible to minimize pitching in strong winds and has been operated in winds up to 25 knots. The sensors installed on the apparatus are listed in Table 1. Sensors installed on the apparatus.
Supplementary data is collected when possible.
As mentioned above, the surface water temperature is different from and generally cooler than the bulk water temperature because of thermal gradients near the surface and because of the formation of a surface skin layer less than 1 mm thick. The pump is operated every 10 minutes for 10 sec and pumps a stream of water to the surface whose temperature is measured by the radiometer before the skin can form. The surface temperature is determined by subtracting this difference from the 10-cm thermocouple temperature. The advantage of this method is that the radiometer does not need to be of high absolute accuracy or stability and sky radiative effects cancel. Alternately, IR measurements of the sky radiation in the 8-14 micron region can be used.