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Primary Productivity (PP) |
| PP was estimated using recently published models
(Harding et al., 2002 – Estuarine, Coastal & Shelf Science 55: 437-463)
applied to remotely sensed data collected from 1989 to 2001. The models are
“depth integrated models” or DIMs that use inputs on phytoplankton biomass as
surface chlorophyll concentration (B = chl-a), available light (E0),
sea surface temperature (SST), photic depth (Zp) – the depth to which
1% of surface light penetrates, water column depth (H), daylength (Dirr),
and a “physiological” measure, optimal photosynthesis,
normalized to chl-a (PBopt).
The models were developed using data we collected over a period of nearly two decades (1982-1998)
on >60 cruises. Additional data not used in model development (1999-2000) were used for validation.
The form of the models that we applied to remotely sensed data embedded a separate model for
PBopt, making it possible to compute PP without the
need for a measured physiological property. Source data
for the PP images presented here were mapped data from aircraft for chl-a and SST
that were merged with the
nearest cruise data to obtain inputs on properties that we do not measure remotely. The resulting
time-series of PP illustrates seasonal, annual, and inter-annual patterns in Chesapeake Bay,
largely reflecting the strong regulation of phytoplankton dynamics in the estuary by freshwater
flow and the attendant loading of nutrients. PP data for the most recent
three years are posted here
and the complete data set will appear in the near future.
(We are in the process of adding time-series animations for each year's chlorophyll and primary productivity data that we post. Playback of the movie loops may vary according to your browser. For some earlier browsers, it may be necessary to " click" on the first image in the series to begin the loop. If you have problems viewing the animations, please contact us at cbrsp@hpl.umces.edu)
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