Project Funding: 2014 - 2016

NRA: 2013 NASA: Terra and Aqua   

Funded by NASA

Abstract:
This proposal addresses the science data analysis of the MODIS algorithm for particulate inorganic carbon ("PIC," or suspended calcium carbonate). The algorithm works by deriving PIC optical backscattering, which is converted to PIC concentration. It detects CaCO3 of coccolithophores due to their relatively high abundance in the sea and their extremely high PIC-specific optical backscattering. Biological oceanographers have generally focused on the most visible, mesoscale coccolithophore blooms at high latitudes (representing 5% of time and space), as compared to the much-less-abundant coccolithophore populations found in other environments (95% of time and space). This algorithm allows populations to be discerned whether they are in blooms or at lower concentrations, has been validated in every major ocean on Earth, and is now mature enough to be addressed in this "science and data analysis" proposal. Specifically, we have five objectives: 1) define the important scales of variability of PIC by comparing results from MODIS and MISR sensors (the former has 1km resolution, the latter has 275m resolution), 2) address whether PIC has significantly changed over the MODIS missions, both globally and regionally (in the Longhurst biogeochemical provinces), 3) examine whether there have been changes in the annual phenology (time of annual bloom and senescence) of coccolithophores, on a global or regional basis, 4) assess  whether the turnover of PIC (set by production rates minus loss rates associated with grazing, dissolution, and sinking) has varied over the period of the MODIS missions, and 5) determine whether the global distribution of coccolithophore PIC is significantly affected by the geographical position of hydrographic fronts and whether bloom timing is being affected by major wind events and changes thereof. Under the rubric of "Carbon Cycle & Ecosystems," the significance of the proposed work focuses on the cycling of carbon within the ocean, specifically by one functional group, the calcifiers. Elucidation of long-term trends and changes in phenology will have strong relevance to ocean biogeochemistry, especially given the importance of PIC to the rate of the biological pump. Our application of MISR to coccolithophore studies will allow smaller-scale measurements of blooms at ~1⁄4 the spatial scale of MODIS, which will provide insights about the various physical processes affecting their distribution in space and time. The advent of Aquarius salinity data, when combined with MODIS SST data, now allows the estimation of sea surface density and, using gradient finding algorithms, will allow us to determine whether steep gradients in coccolithophore density fall at major ocean hydrographic boundaries. Various other data sets available from the current constellation of Earth observing satellites (e.g., wind speed) will also allow better understanding of the importance of frontal boundaries and wind mixing (using AMSR-E; Aquarius), as they influence global calcite production in the sea. This proposed work directly focuses on two of NASA's fundamental questions in Earth science: (a) "how is the global Earth system changing?" and (b) "what are the sources of change in the Earth system, their magnitudes, and trends?" The work also contributes to other critical NASA Earth science goals: to quantify global productivity, biomass, and carbon fluxes; and to understand how marine ecosystems (of which PIC is a major part of the global carbon cycle) are changing. This research will yield new knowledge about the turnover within the carbonate system as ocean ecosystems respond to global environmental change.

Publications:

Balch, W. M., Bates, N. R., Lam, P. J., Twining, B. S., Rosengard, S. Z., Bowler, B. C., Drapeau, D. T., Garley, R., Lubelczyk, L. C., Mitchell, C., Rauschenberg, S. 2016. Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance. Global Biogeochemical Cycles. 30(8), 1124-1144. DOI: 10.1002/2016GB005414 

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

Collister, B. L., Zimmerman, R. C., Sukenik, C. I., Hill, V. J., Balch, W. M. 2018. Remote sensing of optical characteristics and particle distributions of the upper ocean using shipboard lidar. Remote Sensing of Environment. 215, 85-96. DOI: 10.1016/j.rse.2018.05.032

Hopkins, J., Balch, W. M. 2018. A New Approach to Estimating Coccolithophore Calcification Rates From Space. Journal of Geophysical Research: Biogeosciences. 123(5), 1447-1459. DOI: 10.1002/2017JG004235

Maranon, E., Balch, W. M., Cermeno, P., Gonzalez, N., Sobrino, C., Fernandez, A., Huete-Ortega, M., Lopez-Sandoval, D. C., Delgado, M., Estrada, M., Alvarez, M., Fernandez-Guallart, E., Pelejero, C. 2016. Coccolithophore calcification is independent of carbonate chemistry in the tropical ocean. Limnology and Oceanography. 61(4), 1345-1357. DOI: 10.1002/lno.10295

More details may be found in the following project profile(s):

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile