Summary

The general goal of this project is to define over time the horizontal and vertical structure of the light field and biogeochemical variables, and consequent light constraints for primary production in the waters of the Equatorial Atlantic under the effects of the Amazon River discharge. This goal will be accomplished through a combination of unique in situ bio-optical data acquisition and derived proxies, radiative transfer modeling, temporal series of biochemical variables derived from ocean color MODIS satellite imagery, and biogeochemical modeling (ROMS/PISCES) already being used by the UFPE research group (Dr. M. Araujo). 

 
 
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Objectives

To accomplish the goals of this project, the following objectives will be addressed:

01. Characterize the vertical and horizontal in-water light field and associated bio-optical and biochemical variables based on in situ and radiative transfer models to address limitations for primary production

02. To derive validated biochemical and optical products from MODIS ocean color imagery to address temporal and small horizontal scale phenomena that are not solved with traditional data collection methods, such as ship based and Lagrangian floats

03. To investigate bio- optical and satellite products data assimilation to improve ROMS/ecological coupled model ability to describe the carbon cycle, and to validate model products. For instance, improvements of the ROMS/ecological coupled model require the photosynthetic light field and other optical properties, such as dissolved organic matter and chlorophyll attenuation, which this project will quantify. 

Project Location

This research is being carried out in Brazil focusing on the Equatorial Atlantic.

Methods

To address the specific objectives, this project will carry out several tasks: (i) conduct two surveys in the Equatorial Atlantic under the influence of the Amazon discharge for in situ quantification of water optical properties and optical compounds; (ii) compile a time series of aerosol optical depth derived from the AERONET sun photometer installed in Bragança, Tucuruí, and Santarém, and MISR/Terra satellite derived aerosol optical depth for validating atmospheric correction of MODIS imagery; (iii) validate semi-analytical optical models to derive biochemical products from MODIS imagery; (iv) assimilate bio-optical data and imagery products for running and validating biogeochemical models solutions (ROMS/ecological model). 

Cruises were conducted in September-October in two consecutive years, 2013 and 2014, to collect in situ data for quantifying bio-optics and biochemical variability.  Check out some of the pictures of our 2014 field season:

Track line of the cruise to track the Amazon River plume into the tropical Atlantic.  

Track line of the cruise to track the Amazon River plume into the tropical Atlantic.