Balch, William (Barney): Bigelow Laboratory for Ocean Sciences (Project Lead)
Project Funding:
2010 - 2013
NRA: 2009 NASA: The Science of Terra and Aqua
Funded by NASA
Abstract:
This proposal deals with the MODIS algorithm for particulate inorganic carbon ("PIC" or suspended calcium carbonate). The algorithm works by deriving PIC optical backscattering from which PIC concentration ultimately is calculated. It predominantly detects CaCO3 of coccolithophores due to their relatively high abundance in the sea and extremely high PIC-specific scattering properties. The major challenge to the maintenance of the PIC algorithm, as well as science data analysis of the PIC data product, is a relatively small sea-truth data set, not yet global in scope, for validation purposes. The work proposed here will involve 50% algorithm maintenance (optical measurements made on three cruises from vastly under-sampled regions of the southern Atlantic, Indian and Pacific Oceans) and 50% science data analysis of the mission data sets. Specifically, we will examine 1) improvements to the MODIS PIC algorithm through more globally representative sampling of PIC and its optical properties, 2) optimization of MODIS PIC algorithm accuracy using MISR bi-directional reflectance measurements and 3) a mission-long time series analysis of PIC (examining trends globally, by latitude and by ocean biogeochemical province). NASA will incur no ship time expenses for any of the algorithm maintenance work; two of the cruises (S. Atlantic and S. Indian) are already funded by NSF for unrelated biogeochemical studies of coccolithophores. We have been invited to join a third New Zealand cruise to the S. Pacific. In all cruises, we will sample various parts of the "Great Coccolithophore Belt", an 88x10^6 square kilometer feature of calcite-enhanced water that extends around the globe in the region of the Antarctic subpolar front. We here propose to incorporate bio-optical measurements, specifically in support of the NASA PIC two-band/three-band algorithm maintenance, and, equally important, to process these optical data to the level of NASA climate data records. For all cruises, we will make a combination of underway ship measurements for IOPs and AOPs, which when combined with discrete particle analyses will provide new validation data for the algorithm. We will do statistical analyses in order to extrapolate satellite PIC measurements from the top optical depth to the entire euphotic zone (or deeper), depths effectively invisible to the ocean color satellites but of great biogeochemical relevance, nonetheless. Funds are requested for adding a fluorometer for colored dissolved organic matter to our sampling system, so that we can better evaluate the impact of CDOM on the PIC algorithm performance.
This proposal addresses 2 of the 6 Earth science focus areas: 1) Carbon Cycle and Ecosystems plus 2) Climate Variability and Change. It supports 3 objectives identified for NASA Carbon Cycle and Ecosystems research: (1) document and understand how the global carbon cycle, terrestrial and marine ecosystems are changing, (2) quantify global productivity, biomass and carbon fluxes; and (3) provide useful projections of future changes in global carbon cycling and terrestrial and marine ecosystems for use in ecological forecasting, and as inputs for improved climate change predictions. The NASA OBB strategic plan lists two priority observations that will be featured in this work: (A) allow discrimination and quantification of particulate matter in order to deduce the fate of carbon in the ocean and quantify its role as either a source or sink for carbon; and (B) measurements of the distribution, abundance, and variability of plant groups with important ecological and physiological functions to further refine our ability to quantify global sources and sinks, providing accuracy sufficient to balance the global carbon budget.
Publications:
Balch, W. M., Bowler, B. C., Drapeau, D. T., Lubelczyk, L. C., Lyczkowski, E. 2018. Vertical Distributions of Coccolithophores, PIC, POC, Biogenic Silica, and Chlorophyll a
Throughout the Global Ocean. Global Biogeochemical Cycles. 32(1), 2-17. DOI: 10.1002/2016GB005614
More details may be found in the following project profile(s):
