gaps of 2 to 3 weeks are likely to occur several times per year, with 

 less frequent gaps of longer duration. In winter, low sun elevations 

 will cause sampling voids of several weeks to a few months (increasing 

 with latitude) at latitudes above 40 degrees. These characteristics 

 assume that a single CZCS-type instrument is operated in a Nimbus-7 

 orbit on a global basis (for the approximately 25 percent of each orbit 

 with suitable solar elevation). 



Clearly the present data base collected with the Nimbus-7 CZCS is inade- 

 quate to apply to the global mapping of primary productivity, except in a 

 qualitative sense. It is limited both in terms of sampling frequency and 

 in terms of concurrent oceanographic experimental data necessary to bridge 

 the interpretive gap from phytoplankton pigment distributions to net 

 primary production. Adequate data do exist in certain shelf regions (Table 

 4-1), however, to develop a sampling methodology for a global productivity 

 assessment program (Table 4-2) utilizing a follow-on CZCS-type sensor . It 

 is intended to deploy moored vn situ fluorometers, as discussed pre- 

 viously, and drifting fluorometers, similar to the meteorological sensors 

 of the 1979 Global Weather Experiment, in defined 1987-89 MAREX shelf 

 experiments to allow interpretation of time-space composite descriptions 

 of at least parts of the ocean. With global sampling, CZCS-type images 

 will permit instantaneous resolution of the shapes of shelf synpotic-scale 

 patterns of phytoplankton pigment distribution from any domain. These 

 images will also permit interpolation rather than extrapolation from this 

 data set (Table 4-2). 



In general, phytoplankton standing stock and pigment concentration 

 levels at a fixed time within a particular pattern feature are the 

 result of a complicated set of biological, chemical, and physical 

 processes with time scales ranging from seconds to seasonal, and space 

 scales ranging from global to microscopic (Table 2-1). The shapes and 

 locations of patterns delineating meso- and synpotic-scale shelf 

 features are dominated, however, by physical-dynamical processes trans- 

 porting the plankton populations. Therefore, meso-scale patterns (10 < 

 x < 100 km) tend to evolve over time scales ranging from several hours 

 to a few days (i.e., at the time scale of a moored or drifting fluoro- 

 meter array), while the synoptic-scale patterns (100< x <1000 km) tend 



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