Primary Productivity Round Robin (PPARR4)

[OB.DAAC - SeanBailey]

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
March 2008.

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 marjy@vims.edu if you are interested in participating in this comparison or
if you have further questions about the PPARR project.

Thank you,

Marjy Friedrichs, Mary-Elena Carr and Vince Saba

References:

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, Johnng
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.