ocean_color

Tools and algorithms for drone and satellite based ocean color science

Currently in the process of implementing a few of the NASA Ocean Color team's chlorophyll retrieval algorithms from https://oceancolor.gsfc.nasa.gov/atbd/chlor_a/. The goal is to make these algorithms more easily understandable and to allow fine-tuning for sensors that differ from the primary NASA ocean observing satellites, particularly for drone-based multispectral sensors. This is all done right now using the NASA bio-Optical Marine Algorithm Dataset (NOMAD) available at https://seabass.gsfc.nasa.gov/wiki/NOMAD.

Currently implemented algorithms:

• Hu et al 2012 color index (https://doi.org/10.1029/2011JC007395) - code
  • complete and exactly replicates the nonlinear regression coefficients, r-squared, and RMS from the paper.
  • this is the algorithm NASA uses for oligotrophic (low-productivity) waters in the global ocean
• OCx algorithm (originally via https://doi.org/10.1029/98JC02160 but more recently updated on https://oceancolor.gsfc.nasa.gov/atbd/chlor_a/) - code
  • nearly exact but the exact filtering procedure and curve matching approach isn't outlined
  • will be updating to match https://doi.org/10.1016/j.rse.2019.04.021 at some point

Application examples

• applying the OCx algorithm on Landsat 8's Provisional Aquatic Reflectance product - code

January 5, 2021 image from VIIRS (credit NASA Ocean Color)