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Inherent and apparent optical properties of Tampa Bay: What controls light attenuation?

Chengfeng Le, University of South Florida, chengfeng@marine.usf.edu
Chuanmin Hu, University of South Florida, hu@marine.usf.edu (Presenter)
David English, University of South Florida, denglish@marine.usf.edu
Jennifer Cannizzaro, University of South Florida, jpatch@marine.usf.edu
Zhiqiang Chen, University of South Florida, zchen@marine.usf.edu
Charles Kovach, Florida DEP, charles.kovach@dep.state.fl.us
Chris Anastasiou, Florida DEP, chris.anastasiou@dep.state.fl.us
Jun Zhao, University of South Florida, junzhao@marine.usf.edu
Kendall Carder, University of South Florida, kscarder@msn.com

Inherent (IOP) and apparent (AOP) optical properties of Tampa Bay (Florida, USA) were measured during fourteen cruises between February 1998 and October 2010 to understand how these properties relate to one another and what controls light absorption and diffuse attenuation in this moderately sized (~1000 km2), shallow estuary (average depth ~ 4 m). The IOPs and AOPs included: 1) absorption coefficients of three optically active constituents (OACs): phytoplankton pigments, detrital particles, and colored dissolved organic matter (CDOM); 2) particulate backscattering coefficients; 3) chlorophyll-a concentrations; 4) above-water remote sensing reflectance; 5) downwelling diffuse attenuation coefficients (Kd) at eight wavelengths and photosynthetically active radiation (PAR). Results showed substantial variability in all IOPs and AOPs in both space and time, with most IOPs spanning more than two orders of magnitude and showing strong co-variations. Of all four bay segments, Old Tampa Bay showed unique optical characteristics. During the wet season, blue-green light absorption was dominated by CDOM, while during the dry season all three OACs contributed significantly. However, the variability in Kd(PAR, 490nm, 555nm) was driven mainly by detrital particles and phytoplankton as opposed to CDOM. This observation explained, at least to first order, why a nutrient reduction management strategy used by the Tampa Bay Estuary Program since the 1990s led to improved water clarity in most of Tampa Bay. The findings here also provided the optical basis to fine tune existing, or develop new, algorithms to estimate the various optical water quality parameters from space. For example, a new algorithm developed from this data set can reduce RMS uncertainty in MODIS-derived Chl from > 100% to 50% for Chl ranging between 1 and 30 mg m-3.

Presentation Type:  Poster

Session:  Science in Support of Decision Making   (Wed 10:00 AM)

Associated Project(s): 

  • Hu, Chuanmin: ECOHAB: Remote detection of harmful algal blooms in the Eastern Gulf of Mexico ...details
  • Related Activity

Poster Location ID: 168

 


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