Sosik, Heidi: Woods Hole Oceanographic Institution (Project Lead)
Project Funding:
2009 - 2015
NRA: 2009 NASA: The Science of Terra and Aqua
Funded by NASA
Abstract:
Dynamic physical forcing and complex interactions with adjacent land masses and slope seas combine to make coastal ecosystem change especially challenging to detect and understand. From both biogeochemical and ecological perspectives, the biomass and functional diversity of the phytoplankton are especially important characteristics. Certain types of phytoplankton play key roles in carbon and nutrient cycles at the same time that changes in dominant taxa or size classes may indicate shifts in food web structure and ecologically and societally important trophic transfers (e.g., to commercially important or nuisance species). It is increasingly recognized that MODIS chlorophyll products (as phytoplankton biomass indices) can only inform us about part of this ecological complexity. More information is required about the composition of the phytoplankton community and, while new approaches and remote sensing products are emerging, in situ time series and validation data sets remain sparse and incomplete.
Our goal is to address this challenge with unique phytoplankton time series observations made possible by new sensor technology deployed at existing ocean observing infrastructure on the New England Shelf. We will use the time series to explore and evaluate algorithms that can be applied to MODIS ocean color data, extending beyond phytoplankton biomass to the possibility of functional group or size-class-dependent biomass retrievals.
Observations of phytoplankton and optical properties will be made at the Martha’s Vineyard Coastal Observatory (MVCO), with focus on the combination of automated submersible flow cytometry and automated above water ocean color radiometry (AERONET-OC). This latter component will allow us to separate evaluation of in-water algorithms and properties from possible complications with MODIS-based normalized water leaving radiance retrievals in US northeast coastal waters (likely associated with aerosol property variability). We will also use cruises-of-opportunity to extend phytoplankton observations farther across the shelf, including the shelf break frontal zone, which will be the site of extensive research as a focus of the emerging Ocean Observatories Initiative (NSF).
There are five specific project objectives:
1) To extend and analyze the existing phytoplankton community time series at MVCO with focus on resolving seasonal-to-interannual patterns and modes of variability;
2) To similarly extend and analyze the existing AERONET-OC times series at MVCO for coastal ocean color validation and expanded understanding of uncertainty sources for ocean color product retrievals;
3) To generate new cross-shelf (extending from MVCO) observations of phytoplankton community composition in select seasons;
4) To explore (and possibly adapt) published approaches to retrieve phytoplankton functional groups and/or size classes from AERONET-OC / MODIS normalized water-leaving radiance on the basis of comparison with the in situ time series; and
5) To use MODIS products (existing and exploratory) to develop approaches and criteria for extending the spatial-temporal foot print of phytoplankton community characteristics beyond the locations of detailed in situ measurements (e.g., MVCO).
Achieving these objectives will contribute to greater understanding of phytoplankton bloom dynamics and the factors that influence community structure in coastal ecosystems. The proposed research will address broad NASA Earth Science goals related to forcing of ecosystem change and impacts of shifts in biodiversity at different space and time scales. It is responsive to the solicitation under the Ocean Biology and Biogeochemistry Measurement Team and the Biodiversity and Ecological Forecasting Team priorities, including coastal validation and use of MODIS data products to understand ocean ecology and biodiversity.
2011 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)
- Seasonal to interannual variability in phytoplankton biomass and diversity on the New England Shelf: In situ time series for validation and exploration of remote sensing algorithms
-- (Heidi M Sosik, Hui Feng)
[abstract]
More details may be found in the following project profile(s):
