Welcome to my research world! I am a biological oceanographer who aspires to be a bio-optical oceanographer - something not entirely different, but certainly more technical. There's quite a bit of physics and math involved, but I'm getting used to reading in Greek letters and I'm no longer freaked out by modeling stuff on my computer. I'm a full-fledged nerd! Sweet.

So, that said, I put this page up for a few reasons:

1) It helps my friends and family understand what the heck I'm doing in graduate school, and why I spend so much time grumbling in front of my computer;

2) It informs other researchers of what I'm interested in and what experience I have, just in case they are looking for someone to collaborate with; and lastly

3) It is shameless self promotion, for better or for worse. This is what I do and why I do it. Wanna hire me sometime in 2006? See my CV here...

My early research focused on trying to characterize the shape of the particulate backscattering spectrum for particles in the ocean. There have been numerous modeling studies of spectral backscattering for phytoplankton, microzooplankton, bacteria, bubbles, minerals, etc., but actual measurements of these things are hard to come by.The data set that I worked with is a set of SlowDROP profiles from off the coast of New Jersey, from the summer of 2001 (HyCODE/LEO-15). Without getting into the gory details of measurement techniques and data analysis methods, I'll give you some idea of what I'm up to. Have yourself a look at the figure to the left (click it for a bigger version). It's got something like seven thousand spectra, so pardon me for the jumbled mess. On the x-axis we've got wavelength, or the color of light where we've measured backscatter (in nm). On the y-axis we have the magnitude of backscattering by particles in the ocean (bb by seawater removed according to Boss and Pegau, 2001). The color of the line is the 'chlorophyll' content (ac9 derived chlorophyll line height, for those in the biz) for each measured bit of water, which gives you an idea of how much algal biomass is in the water (where red is high, and blue is low). Notice the range in both the magnitude of the measured bb (~0 - 0.04/m) and in the shape if the spectrum (relatively flat at the bottom, and fairly curved up top). Both the magnitude of backscattering and the shape of the spectrum give me with information about what's in the water. Isn't that neat?! I think it's WAY interesting (in the parlance of our times), and I am totally jazzed about the whole thing. In the most general sense (i.e. all else being equal), a steeper spectrum indicates a community of relatively smaller particles. A flat spectrum indicates larger particles. A high magnitude of backscattering indicates that there could be a high particle load in the water, and/or there are particles present with a high backscattering efficiency (like sediment particles, for example). The trick is trying to figure out how much each of these various particles are contributing to the magnitude and shape of these measured spectra. For details of the results of this work, see my ASLO poster below.

My current research is focused on the scattering properties of marine phytoplankton cultures. In May 2004 I participated in a phytoplankton scattering workshop at the University of Maine. We measured the optical properties of several major phytoplankton groups to determine if they have unique optical signatures. Measurements included spectral backscattering, the VSF at two wavelengths and three angles, POC, Chl, forward scattering from 1.5 - 19 degrees, and spectral absorption and attenuation at nine wavelengths.

My specific contribution to the workshop is to investigate how backscattering varies between species, both in magnitude and in spectral shape. I will also be comparing the variability in backscattering to various parameters like POC, cell concentration, and chlorophyll in order to understand what is contributing to the observed changes in bb.

You can read about initial results in my extended abstract for Ocean Optics 2004 below. You can also check out the two figures at left (click to enlarge). The first figure shows the chlorophyll concentration for each culture (x-axis) plotted against particulate backscattering in the green range (555nm, y-axis). What you can see is that the chlorophyll concentration is not a good predictor of the magnitude of backscattering for cultures. This means that a high chlorophyll concentration does not necessarily lead to high backscattering. Food for thought...

The second plot shows particulate backscattering spectra for phytoplankton cultures, normalized at bbp620. I normalized the cultures to a common wavelength to emphasize differences in the shapes of the spectra. The culture labels (skel, tps, gym, etc.) are somewhat cryptic, but the main gist of the plot is that cultures with larger cells have flatter spectra than smaller celled cultures. This result agrees well with what I found in the in situ data at HyCODE - smaller cells = steeper spectra. Excellent! When I finish my poster, I'll put it online so you can get all of the plots and meaty details. Enjoy!

The NRL/OSU/NavAir Scattering Workshop

Briggs, A.L., Pegau, W.S., Weidemann, A., and Prentice, J. Evaluating forward scatter measurements. Ocean Optics XVI, Santa Fe, NM, November 2002. Extended Abstract (Word) Poster (PowerPoint)