Figure 5. Downwelling irradiance (Ed) in the blue (443-nm), green (530-nm), and yellow (589-nm) wavelength channels, respectively, sampled on the night of August 12^th, 2015, at 22:00 local time, in the Gulf of Aqaba water column at station i4 (see Fig. 2).

Ed ranged from 4.6 × 10⁻⁴ to 1 × 10⁻⁶ μW cm⁻² nm⁻¹ in the 589-nm (yellow) channel, from 7 × 10⁻⁵ to 1 × 10⁻⁶ μW cm⁻² nm⁻¹ in the 520-nm (green) channel, and from 1.3 × 10⁻⁴ to 5.8 × 10⁻⁵ μW cm⁻² nm⁻¹ in the 443-nm (blue) channel. The irradiance of green and yellow light reached the instrument limit at depths of 15 and 20-m, respectively. The irradiance of blue light did not reach noise level down to the maximum depth to which the instrument was deployed (30 m).