Today we feature Dan Otis from USF

Welcome back!

Nancy Foster in port, St. Thomas, USVI

I hope you enjoyed the first few posts, and there is more to come! We will be at sea until June 3rd!

Our research-cruise is made up of 4 "legs" --one leg = two week periods, between which there's a port stop. Each leg has a different science party, with some people leaving, others coming aboard, and a handful that stay the whole time. As you can imagine, we had to play Tetris with everyone's schedules! This "leg," the science party is made up of 13 scientists + engineers that fix everything all day long +the deck department that keeps the ship + equipment running, the chefs that feeds everyone (thank you!), + NOAA corps officers that drive the ship and handle day to day logistics. You can learn a lot about this ship and some of their past/current missions at their website (or "Like" them in their FB): NOAA SHIP NANCY FOSTER.

Today we will start to feature our scientists on our blog and learn a bit about them and why they decided to join us in our cruise through the Caribbean! Today we will start with Dan Otis.

Dan is a “post-Doc” (aka Postdoctoral scholar) at the University of South Florida’s College of Marine Science in the Institute for Marine Remote Sensing (IMaRS) in St. Petersburg, FL. 

Dan is measuring remote-sensing reflectance. In between his continuous filtering of water, he explained a little about it: “Remote sensing reflectance is just the ratio of the amount of sunlight reflected by a surface (the ocean in this case) to the amount of downwelling or incoming sunlight. In this case it's around 2%. For a solid surface like concrete on the sidewalk, it might be 50% or more. The ocean is very “dark” in this sense because most of the incoming light is absorbed. We are also measuring reflectance by wavelength, meaning how much blue light is reflected...how much green light, etc.”

These measurements tell us about phytoplankton pigments, plankton in the water, and how much light is being absorbed and reflected. He uses an instrument called a spectro-radiometer, which measures individual wavelengths of light. On station, he takes 3 sets of measurements at 45 degree angles -

a) calibration using a white card as a standard

b) measurements of the water:

and c) measurements of the sky!

The instrument measures the color of light reflected from the water surface as a ratio compared to incoming skylight.  His measurements are collected during the day hours can be used to validate ocean color satellite estimates of chlorophyll made at the top of the atmosphere. 

Another part of Dan's @sea duties involve filtering water from the CTD's bottles. The "CTD package" is lowered at each station and is 'cast' down to a certain depth (200m if possible). Once recovered, the CTD has many bottles (gray bottles on left) that collect water at different depths. Dan collects water from the surface bottle and filters and filters and filters water in order to measure the absorption of light by phytoplankton. 

CTD package being recovered by NOAA Corps officers Jim Europe, Aras Zygas and Alexis Sabine (DPNR)

We hope Dan's measurements can enhance the limited knowledge we have about remote sensing in this part of the world!