What is C-HARM?
The California-Harmful Algae Risk Mapping (C-HARM) Model generates predictions of harmful algal bloom (HAB) conditions through a combination of 1) sophisticated circulation models that predict the ocean physics, 2) satellite remote-sensing data of the ocean “color” and chlorophyll patterns, and 3) statistical models for predicting bloom and toxin likelihoods. These predictions are generated daily to provide a forecast of where you might encounter a Pseudo-nitzschia bloom and/or domoic acid event in the next one to three days.
What does C-HARM predict?
Pseudo-nitzschia Bloom Prediction shows the probability that the abundance of toxin-producing species of the diatom Pseudo-nitzschia is at or above the “bloom” threshold of 10,000 cells per liter. A value of 0.7, for example, means there’s a 70% predicted probability of Pseudo-nitzschia blooms in that pixel. This threshold is based on work in Trainer and Suddleson 2005, Lane et al. 2009, Anderson et al. 2009, 2011, 2016.
Domoic Acid Event Prediction (for particulate DA) shows the probability that the domoic acid concentration in the bulk phytoplankton pool is at or above 500 nanograms per liter (= 0.5 micrograms per L). A value of 0.7, for example, means there’s a 70% predicted probability of a toxic event, although there is always the possibility that concentrations lower than 500 ng/L will lead to toxins in shellfish or strandings of marine mammals and birds. This threshold is discussed further in Anderson et al. 2009, 2011, 2016.
Domoic Acid Toxicity Prediction (for cellular DA) shows the probability that the domoic acid concentration per Pseudo-nitzschia (i.e. how toxic are the algal cells themselves) is at or above 10 picograms per cell (pg/cell). To give a sense of the range, the highest cellular concentrations seen in the environment have not yet exceeded 200 pg/cell in the most toxic cells. A predicted probability value of 0.7, for example, means there’s a 70% probability that a 10 pg/cell level of toxicity is present in the phytoplankton, although there is always the possibility that concentrations lower than 10 will lead to toxins in shellfish or strandings of marine mammals and birds. This threshold is discussed further in Anderson et al. 2009, 2011, 2016.
C-HARM nowcast data can be found here: https://coastwatch.pfeg.noaa.gov/erddap/griddap/charmForecast0day.graph