Project Funding: 2010 - 2013

NRA: 2009 NASA: New Investigator Program   

Funded by NASA

Abstract:
Photosynthetic plankton in the ocean (i.e., phytoplankton) play a critical role in planetary biogeochemistry and its carbon cycle in particular. These microbes fluoresce when exposed to ambient sunlight and this 'natural' phytoplankton fluorescence has generated considerable interest among oceanographers and climatologists as a potentially useful tool for examining marine photosynthesis, an important biogeochemical process. This fluorescence can be seen in the ocean's water-leaving radiance spectrum and is easily measured using simple radiometers including those on satellites such as NASA's MODIS. Yet although the ocean's natural fluorescence signal may be easy to measure it still remains challenging to interpret despite several decades of effort. Most frameworks for interpreting remote sensing fluorescence signatures of the ocean are time-independent and do not take into account dynamical changes that alter fluorescence emission over the course of the day. Yet such dynamical behaviors are central to interpreting natural fluorescence in a meaningful ecological and biological context, not only as measured from current polar-orbiting sensors but from planned geostationary platforms as well. This NASA New Investigator Program research will examine how dynamical system modeling can be used to interpret the fluorescence signature that satellite remote sensors record from the surface ocean. This research will involve the use of two open-ocean moorings, outfitting each with radiometers to generate multi-year climatologies of the dynamical behaviors in natural fluorescence and related ocean color properties. These field observations will support a modeling study aimed at refining a dynamical model the PI has developed for interpreting remotely sensed ocean fluorescence signatures. A more robust dynamical understanding of natural fluorescence variability is essential for determining what types of physiological or ecological inferences can be drawn from satellite-sensed fields of this property, and how these fields are affected by ubiquitous environmental processes in the surface ocean such as winds and cloud cover. The New Investigator in this project will partner with experts in open-ocean moorings and develop a strong interdisciplinary collaboration that mutually advances the use of moorings for ocean color research. This mooring study will represent an important source of ground-truthing data for NASA's ongoing remote sensing program for chlorophyll fluorescence, which currently lacks comprehensive or synoptic in situ climatologies from the open oligotrophic ocean. The outreach component of this New Investigator project will utilize an existing education and outreach network at the Investigator's institution, in order to develop a permanent interactive learning exhibit at its Ocean Science Exhibit Center.

2011 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• Assessing natural fluorescence dynamics using radiometry on long-term ocean moorings   --   (Samuel Laney)   [abstract]