5-10 km in the horizontal. The instruments will be sampled at 10-minute intervals and will 

 have an endurance of 3-4 m. 



TOYO and Surface Mapping: We propose to make FRR measurements on all TOYO 

 deployments. The resulting high- resolution profiles have a vertical resolution of 1 m, a 

 horizontal resolution of ~1 km and a repeat cycle time of 5-10 minutes. In addition, a shipboard 

 FRR fluorometer may be used to provide continuous near-surface maps of the photosynthetic 

 parameters. 



CTD Profiling: On process cruises we propose to make in situ FRR measurements on all CTD 

 casts. These profiles will have a vertical resolution of 1-3 m, and their horizontal resolution will 

 be determined by the station spacing, which is expected to be 1-15 km. 



Discrete Sampling: On process cruises we propose to make FRR fluorescence measurements on 

 discrete samples collected as part of our investigations of photosynthesis. 



METHODS AND PLATFORMS 



Platforms: This project includes both mooring and shipboard support We propose to deploy five 

 FRR fluorometers in the moored array and will require 1 berth on mooring cruises. On processes 

 cruises this project will require 1-2 berths. 



Methods: Primary production is a highly dynamic phenomenon because it is governed by nutrient 

 availability, solar irradiance, and temperature. Physical processes distribute the phytoplankton 

 cells, and the subsequent transformations occur over a wide range of time and space scales. 

 Since the relative importance of various physical and biological processes varies seasonally and 

 spatially, the OMP will require an array of moored instrumentation to measure photosynthetic 

 parameters of phytoplankton over long temporal scales, as well as the ability to rapidly map large 

 areas to acquire a mesoscale distribution of photosynthetic parameters at selected time intervals. 



A fluorescence based methodology called fast repetition rate (FRR) fluorometry will be 

 used to rapidly measure the rates of photosynthesis and quantify the fundamental parameters 

 controlling these rates. The FRR methodology is based on sound, biophysical principles of light 

 absorption, photochemistry, and carbon fixation. The basics of FRR methodology have been 

 verified in both laboratory and field conditions, and the methodology continues to evolve. 

 Instrumentation implementing the FRR methodology has been used in the TOYO, profiling, and 

 discrete modes for more than a year. 



STRENGTHS AND LIMITATIONS OF PROPOSED RESEARCH 



The FRR fluorometer strengthens the OMP program because it can be used to measure 

 the distribution of the photosynthetic parameters with high spatial and temporal resolution. 



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