Simulation of natural oceanic conditions in a laboratory setting is a challenging task, especially when that environment
can be miles away. We present an attempt to replicate the solar radiation expected at different latitudes with varying
water clarity conditions up to 30 m in depth using a 2.5 m deep engineering tank at the University of New Hampshire.
The goals of the study were: 1) to configure an underwater light source that produced an irradiance spectrum similar to
natural daylight with the sun at zenith and at 60° under clear atmospheric conditions, and 2) to monitor water clarity as a
function of depth. Irradiance was measured using a spectra-radiometer with a cosine receiver to analyze the output
spectrum of submersed lamps as a function of distance. In addition, an underwater reflection method was developed to
measure the diffuse attenuation coefficient in real time. Two water clarity types were characterized, clear waters
representing deep, open-ocean conditions, and murky waters representing littoral environments. Results showed good
correlation between the irradiance measured at 400 nm to 600 nm and the natural daylight spectrum at 3 m from the light
source. This can be considered the water surface conditions reference. Using these methodologies in a controlled
laboratory setting, we are able to replicate illumination and water conditions to study the physical, chemical and
biological processes on natural and man-made objects and/or systems in simulated, varied geographic locations and
environments.
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