Part One: Consider an ocean region where irradiance just below the ocean surface is 500 E m-2 s-1 and the light attenuation coefficient is 0.44 m-1. At what depth is the light intensity 15 E m-2 s-1 ? Part Two: Now, in this part of the ocean, the mixing layer is 30 m deep. Assuming a phytoplankton cycles vertically within this layer as mixing occurs (so that it visits all depths for equal amounts of time), calculate the average light it receives. Is this value greater than 15 E m-2 s-1 ? (Need to derive a formula for the average light over a mixed-layer of depth D, and then set D to 30 m to answer this question) Part Three: if the mixed layer is too deep, then the average light intensity would be less than 15 E m-2 s-1 and phytoplankton populations would not increase. When will this happen? Using the formula found in Part Two, find the mixing layer depth D at which the average intensity in the mixing layer is exactly 15 E m-2 s-1 . Use the following methods to solve this problem: Calculate the formula from Part Two for lots of different D and find