Ok, quite a bit of stuff to share with you this week. Most if it is the data I collected in the lab this week. First off, the paper on the data we collected at DMC is done, but you already knew that. It is going to be exciting after we collect data next week to see if the new data reinforces our 550/500 ratio. So, that brings me to my first topic which is our new light source.


In the lab this week I measured the output of our new light with the radiometer. I placed both the radiometer and the light source in the sink and filled it with water. I propped the spectralon plate up against the far side of the sink. The setup was similar to when Wayne and I and looked at LED lights in the lab, except this time the light and radiometer were submerged. First I logged data for only a minute or so to see what the spectra looked like. I also pointed the LEDs of the DiveSpec and the radiometer at the spectralon plate. However this was not done underwater. The graph below displays spectra from the AquaSun, the DiveSpec, and from Wayne’s LED flashlight.

Interestingly enough, they all appear to be quite different. Next I let the light run for ten minutes in the sink while logging data. This is what the spectra looked like. The numbers on the color bar are in seconds.

Over the ten minute period the brightness of the light had dropped! I assume the brightness of the light will drop to a certain level then remain constant. I looked over the box after I was done and discovered that this is mentioned on the back of the box. On the back of the box there is a small graph of lumens vs. time. It shows that it starts high and drops slightly for the first 10-15 minutes, then levels out. Hopefully this won’t be too big an issue. I figure as long as the shape of the spectra remains relatively constant, we are going to be OK.
In the lab I also measured the blue LEDs of the DiveSpec used during the fluorescence function with the radiometer. I measured them the same way i measured the white LED lights. Just like with the white LED lights this measurement was not done underwater. Below is the spectrum of the blue LEDs.

It appears that Didemnum may fluoresce! The spike at 550 was not produced by the DiveSpec LEDs. This is what I expected, but I wanted to double check.

Last but not least, I measured our spectralon plate with the DiveSpec. After calibrating the DiveSpec with the 99% reflectance standard, I measured each corner and the center of the plate on each side. Using this data I was able to reshape the radiometer data to how it would look, had it been referenced with the 99% standard. I did this by taking the median of the 10 DiveSpec measurements I took and fitting a linear equation to that measurement.

After that I took the existing data and put it into the equation Reflectance = Lw(sample)*(1.07 – 0.00022713*lambda). This shifted the spectra to what they would have looked like had they been referenced to the 99% reflectance standard. The two graphs show how the spectra changed after applying the above equation. The dashed lines are the original spectra.

These new spectra brought the total standard deviation of our 550/500 ratio down by small amount.

Also this week, I added information on float 6810 to my website. Unfortunately the files sent by 6810 contain more NaNs than actual data, but it did report its location. So I added a map to show its trajectory while it was deployed. The website should be up soon. I will need help from Lisa to add the umaine header and navigation bars, but once that’s done it should be good to go.

Anyway, there is game of disc with my name on it, see you next week!