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Wednesday, February 8, 2023. 3:00 PM. Webinar: Estimating Phytoplankton Size Fractions Using Satellite Models in the Chukchi and Bering Seas. Jens M. Nielsen, University of Washington. Sponsored by NOAA Ocean Color Coordinating Group. More information here. Register here.

Abstract: Here, we compare empirical models which can be used with satellite ocean color data to estimate phytoplankton size-fractionated chlorophyll in the Bering and Chukchi seas. We compared models using total chlorophyll as the predictor for three size-fractions (<, 5-20 and > 20 m). First we assess existing size fraction models, with their global original parameters, and compare them to models which were regionally-tuned using 266 in-situ surface chlorophyll samples for each size, collected in 2017 and 2019. In addition, we tested if other input variables (e.g. sea surface temperature (SST), spatial location) improve predictions of chlorophyll size fractions.

Finally, we assess and compare the utility of general additive and Random Forest models. Comparison among models show the regionally tuned models perform best regardless of size fraction, with total chlorophyll being the most important predictor. SST appears to improve the models primarily for the smallest size fraction. Future implementation of these models with long- term satellite ocean color data can help us understand the effects of long-term environmental change in the Bering and Chukchi ecosystems, and aid the prediction of future trophic scenarios, which is necessary for ecosystem management.