Event Title

Reanalysis of satellite derived chlorophyll-a data for the Salish Sea

Presentation Abstract

Ocean colour remote sensing is a useful tool for monitoring marine ecosystem health through the detection of chlorophyll-a, a proxy for phytoplankton biomass. Phytoplankton are important to marine ecosystems as the base of the aquatic food web. The year 2015 displayed anomalously high chlorophyll-a concentrations in the Salish Sea.

Utilizing the Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) ocean colour satellite (1000m resolution), chlorophyll-a was characterized for 2015. The imagery was processed in order to correct for atmospheric contribution to the signal using a method developed specifically for the Salish Sea. Individual pixels were flagged in order to screen out incorrect or unusable elements, such as those where chlorophyll-a concentrations are overestimated (deemed above 60 mg/m3), the area is obscured by cloud, or the atmospheric correction has failed. Compared to previous years, 2015 displayed uncharacteristically few pixels with chlorophyll-a estimates in the Salish Sea, likely due to the the flagging threshold unaccustomed to such wide scale high chlorophyll-a concentrations, resulting in faulty loss of data.

To account for these flagged pixels, MODIS-Aqua imagery from 2015 of the Salish Sea was reprocessed with revised thresholds for the applied flags. The satellite chlorophyll-a measurements were evaluated in relation to in situ chlorophyll-a data collected by the Ocean Networks Canada (ONC) FerryBox project, citizen science chlorophyll-a data facilitated by the Pacific Salmon Foundation, and chlorophyll-a concentrations collected by DFO. Revising the thresholds and encorportaing in situ data will result in more pixels with chlorophyll-a for analysis.

Session Title

Remote sensing technology to monitor the short and long term dynamic of the Salish Sea

Conference Track

Habitat

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Document Type

Event

Location

2016SSEC

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

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Reanalysis of satellite derived chlorophyll-a data for the Salish Sea

2016SSEC

Ocean colour remote sensing is a useful tool for monitoring marine ecosystem health through the detection of chlorophyll-a, a proxy for phytoplankton biomass. Phytoplankton are important to marine ecosystems as the base of the aquatic food web. The year 2015 displayed anomalously high chlorophyll-a concentrations in the Salish Sea.

Utilizing the Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) ocean colour satellite (1000m resolution), chlorophyll-a was characterized for 2015. The imagery was processed in order to correct for atmospheric contribution to the signal using a method developed specifically for the Salish Sea. Individual pixels were flagged in order to screen out incorrect or unusable elements, such as those where chlorophyll-a concentrations are overestimated (deemed above 60 mg/m3), the area is obscured by cloud, or the atmospheric correction has failed. Compared to previous years, 2015 displayed uncharacteristically few pixels with chlorophyll-a estimates in the Salish Sea, likely due to the the flagging threshold unaccustomed to such wide scale high chlorophyll-a concentrations, resulting in faulty loss of data.

To account for these flagged pixels, MODIS-Aqua imagery from 2015 of the Salish Sea was reprocessed with revised thresholds for the applied flags. The satellite chlorophyll-a measurements were evaluated in relation to in situ chlorophyll-a data collected by the Ocean Networks Canada (ONC) FerryBox project, citizen science chlorophyll-a data facilitated by the Pacific Salmon Foundation, and chlorophyll-a concentrations collected by DFO. Revising the thresholds and encorportaing in situ data will result in more pixels with chlorophyll-a for analysis.