Do you estimate marine photosynthesis using a model? Would you like to quantify the
performance of the model you use? Would you like to know how your model
compares with other models? This is your chance!
We are conducting a study to compare models that estimate primary productivity (PP) from
either ocean-color based models or biogeochemical ocean circulation models, thanks to
funding from NASA’s Ocean Biology and Biogeochemistry Program. This project continues
previous comparison studies (Primary Production Algorithm Round Robins, PPARR).
PPARR3 (Carr et al., 2006; Friedrichs et al., submitted) included over 30 investigators
running ~20 distinct satellite-based PP models or model variants and 9 coupled
biogeochemical ocean circulation models.
The fourth round robin study (PPARR4) includes comparisons to high quality in situ primary
productivity data, including HNLC conditions, intense bloom dynamics, oligotrophy, coastal
dynamics, micronutrient limitation, and high latitude systems. We believe this broad array of
environmental conditions will allow a comprehensive assessment of model estimates of PP,
and their associated uncertainties.
In the PPARR studies, input data (chlorophyll, SST, PAR, and mixed layer depth for specific
locations and dates) are provided by the organizers to the participating modeling groups,
who in turn estimate integrated primary productivity. These results are sent back to the
organizers, who compare and analyze the results. We are preparing to distribute the
PPARR4 data set shortly. The resulting comparisons will be presented at Ocean Sciences in
We welcome the participation of satellite-based PP model users (or developers) as
well as of coupled biogeochemical-circulation modelers who estimate productivity
rates in any of the following regions: BATS, HOT, NABE, Northeast Atlantic, Arabian
Sea, Southern Ocean, Black Sea, and the Mediterranean Sea.
Please write firstname.lastname@example.org if you are interested in participating in this comparison
or if you have further questions about the PPARR project.
Marjy Friedrichs, Mary-Elena Carr and Vince Saba
Mary-Elena Carr, Marjorie A. M. Friedrichs, Marjorie Schmeltz, Maki Noguchi Aita, David
Antoine, Kevin R. Arrigo, Ichio Asanuma, Oliver Aumont, Richard Barber, Michael J.
Behrenfeld, Robert Bidigare, Erik T. Buitenhuis, Janet Campbell, Aurea M. Ciotti, Heidi
Dierssen, Mark Dowell, John Dunne, Wayne Esaias, Bernard Gentili, Watson Gregg, Steve
Groom, Nicolas Hoepffner, Joji Ishizaka, Takahiko Kameda, Corinne Le Quere, Steven
Lohrenz, John Marra, Frédéric Mélin, J. Keith Moore, André Morel, Tasha E. Reddy, John
Ryan, Michele Scardi, Tim J. Smyth, Kevin Turpie, Gavin Tilstone, Kirk Waters, Yasuhiro
Yamanaka, 2006. A comparison of global estimates of marine primary production from ocean
color. Deep-Sea Research II 53, 741-770.
Marjorie A. M. Friedrichs, Mary-Elena Carr, Richard T. Barber, Michele Scardi, David
Antoine, Robert A. Armstrong, Ichio Asanuma, Michael J. Behrenfeld, Erik T. Buitenhuis, Fei
Chai, James R. Christian, Aurea M. Ciotti, Scott C. Doney, Mark Dowell, John Dunne,
Bernard Gentili, Watson Gregg, Nicolas Hoepffner, Joji Ishizaka, Takahiko Kameda, Ivan
Lima, John Marra, Frédéric Mélin, J. Keith Moore, André Morel, Robert T. O’Malley, Jay
O’Reilly, Vincent S. Saba, Marjorie Schmeltz, Tim J. Smyth, Jerry Tjiputra, Kirk Waters, Toby
K. Westberry, Arne Winguth, 2007. Assessing the uncertainties of model estimates of
primary productivity in the tropical Pacific Ocean. Submitted to Journal of Marine Systems,
special issue on biological/physical model skill assessment.
Marjorie A. M. Friedrichs
Virginia Institute of Marine Science
Mail: P.O. Box 1346
Deliveries: Route 1208, Greate Road
Gloucester Point, VA, 23062-1346, USA
tel. +1-804-684-7695, fax. +1-804-684-7889