Field surveys - Light transparency and water temperature profiles, August 2013 (CALON)

Data include raw downwelling irradiance against depth, attenuation coefficients (Kd), and 1% and 10% attenuation depths in meters for 305 nm, 320 nm, and 380 nm ultraviolet light as well as photosynthetically active radiation (PAR; 400-700 nm). BIC units for UV irradiance are in mW cm-2 nm-1, which can be converted to the SI unit mW m-2 by multiplying BIC values by 10. BIC units for PAR irradiance are mmol m-2 sec-1. The attenuation coefficients are calculated using the following relationship: Kd = ln(Io/Iz) / Z where Io and Iz represent the light intensities at an upper and lower depth separated by a depth of Z meters. The 1% and 10% attenuation depths are calculated based upon the Kd value for each wavelength. Note that if the water is highly transparent the calculated 1% and 10% depths can exceed the depth of the lake. Temperature readings for each depth are also made during each profile. The top of the thermocline is estimated as the point where the water temperature drops at least 1 degree Celsius in 1 m.