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The Optical Reef and Coastal Area Assessment (ORCAA) tool in Google Earth Engine allows users to monitor, track, and evaluate water parameters in the Belize and Honduras Barrier Reefs from January 2013 to present using Landsat 8, Sentinel-2, and Aqua/Terra MODIS imagery.

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Optical Reef and Coastal Area Assessment (ORCAA) Tool
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Date Created: November 22, 2019






The Optical Reef and Coastal Area Assessment (ORCAA) tool allows users to monitor, track, and evaluate water parameters in the Belize and Honduras Barrier Reefs from January 2013 through the current date.
It uses a graphical user interface (GUI) so that users can easily add, process, view, and export data. The interface contains four main parts:


        1. a panel to set analysis parameters (time range and area of analysis)
        2. a panel to select analysis types and add images to the map
        3. a panel to export images to Google Drive
        4. a time series chart generator that creates line graphs based on the selected time range, area of analysis, and water quality parameter of interest 


Based on the user selected time range and area of analysis, the tool accesses and filters Landsat 8 Level 2 Surface Reflectance, Sentinel-2 Level 1C, Aqua MODIS, and Terra MODIS collections to create cloud-masked and land-masked collections. The Sentinel-2 collection is also run through the Modified Atmospheric correction for INland waters (MAIN) algorithm developed by Benjamin Page at the University of Minnesota, Twin Cities to atmospherically correct the Sentinel-2 coastal imagery. 


Turbidity, Normalized Difference Chlorophyll Index, chlorophyll-a concentration, and colored dissolved organic matter concentration are calculated from the filtered and corrected Sentinel-2 image collection. Turbidity is also derived from the filtered Landsat 8 collection. Sea surface temperature is taken from the ‘SST’ band in the MODIS collections. 




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 Required Packages
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ORCAA derives all analyses using Google Earth Engine's free and publicly accessible data catalog.
Users do not need to load in their own data, but do need to request an account with Google Earth Engine at code.earthengine.google.com.
Accounts are free and typically approved within a few days. 


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 Parameters
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No steps must be taken to modify the code to enable it to run - users paste the provided code directly into the Google Earth Engine Code Editor and
select "Run." This will load the interface with which users directly interact. The interface includes brief directions to guide users through each analysis option. 


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 Contact
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Names: Vanessa Valenti | Hayley Pippin | Arbyn Olarte | Roxana Pilot
E-mails: [email protected] | [email protected] | [email protected] | [email protected]

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The Optical Reef and Coastal Area Assessment (ORCAA) tool in Google Earth Engine allows users to monitor, track, and evaluate water parameters in the Belize and Honduras Barrier Reefs from January 2013 to present using Landsat 8, Sentinel-2, and Aqua/Terra MODIS imagery.

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