Optical properties and primary production in the Southern Ocean (SO GasEx)

Zhongping Lee, University of Massachusetts Boston, zhongping.lee@umb.edu (Presenter)
Veronica Lance, Science Systems and Applications, Inc., veronica.p.lance@nasa.gov
Shaoling Shang, Xiamen University, slshang@xmu.edu.cn
Robert Vaillancourt, Millersville University of Pennsylvania, robert.vaillancourt@millersville.edu
Scott Freeman, WET Labs, Inc., sfreeman@wetlabs.com
Bertrand Lubac, University of Bordeauxl, bertrandlubac@hotmail.com
Bruce Hargreaves, Lehigh University, brh0@lehigh.edu
Carlos Del Castillo, The Johns Hopkins University, carlos.del.castillo@jhuapl.edu
Richard Miller, East Carolina University, rlmiller@northcarolina.edu
Michael Twardowski, WET Labs, Inc., mtwardo@wetlabs.com
Guomei Wei, Xiamen University, weiguomei@163.com

Optical properties and primary production were measured during the Southern Ocean Gas Exchange Experiment (SO GasEx; March-April, 2008). To assess and evaluate these properties derived from remote sensing, absorption coefficients derived from remote sensing reflectance (Rrs) with the Quasi–Analytical Algorithm (QAA) were compared with those from in situ measurements from both an ac9 optical instrument deployed on a profiling package and from discrete water samples analyzed using filter-pad spectrophotometry. Total absorption coefficients from Rrs retrievals were found, on average, to be ~12% less than ac9 measurements and ~15% less than filter-pad measurements. Absorption coefficients of gelbstoff-detritus and phytoplankton pigments (at 443 nm) derived from Rrs were ~15% and ~25% less than ac9 measurements, respectively. Further, incorporating measured surface radiation data, water-column primary production (PPeu) was estimated using chlorophyll concentration based models (Chl-PP) and a phytoplankton absorption based model (Aph-PP), where remote-sensing Chl was retrieved with an operational empirical algorithm. These estimated PPeu values were then compared with primary productivity measured using 14C incubation techniques, and coefficient of determination (R2, N = 13) of 0.74 were found for the Aph-PP results, while the R2 of the Chl-PP results were less than 0.5. Such a contrast further highlights the importance of analytically retrieving phytoplankton absorption from measurement of ocean color and the advantage of using phytoplankton absorption to represent the role of phytoplankton in photosynthesis. Spatial distributions of PPeu in the greater SO GasEx region estimated from satellite data are also presented.

Presentation Type:  Poster

Session:  Other   (Wed 10:00 AM)

Associated Project(s): 

• Lee, Ping: An IOP centered system to correct the dirctional effects of water-leaving radiance for both oceanic and coastal waters ...details
• Lee, Ping: Optical Properties in the Southern Ocean: In situ and satellite observations in support of Southern Ocean Carbon Program ...details

Poster Location ID: 191