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Harmful Algal Bloom Forecasting

Ocean Shorts: Episode 17

MODIS Aqua satellite image of the Gulf of Mexico from October 23, 2011

Monitoring a Bloom

MODIS Aqua satellite image of the Gulf of Mexico from October 23, 2011, showing areas of elevated chlorophyll a (in red and orange). NOAA's Harmful Algal Bloom-Operational Forecast System (HAB-OFS) analysts monitor these images and other data for areas of high chlorophyll that may be algal blooms. Of course, not all algal blooms are harmful so HAB-OFS rely on additional data for their forecasts.


HOST: Welcome to Ocean Shorts where we revisit popular Making Waves and Diving Deeper episodes. I’m your host Kate Nielsen. Today, we’ll take a few minutes to explore how we forecast harmful algal blooms. In November 2013, I was joined by Allison Allen with the Center for Operational Oceanographic Products and Services to talk about this topic.

Let's listen in.

HOST: So, seeing as how HABs have a huge negative impact for coastal communities, what can we do about this? Can we prepare for these events in some way?

ALLISON ALLEN: We can. Finding and measuring harmful algae has historically been difficult and labor intensive. For instance, research cruises to collect and analyze water samples, while both important and accurate, can be time and resource intensive, so it's been really important to develop methods for forecasting harmful algal blooms, particularly in the areas with the greatest ecosystem, health, and financial impacts. Advanced warning of HABs increases the options for managing these events and their impacts and it can decrease the cost of dealing with the event and the time it takes to rebound from the event as well. So to this end, NOAA is developing Harmful Algal Bloom forecasts and the forecasts are provided to state resource managers and other decision makers to take necessary action, for instance, issuing beach or shellfish bed closures.

HOST: What kind of data do you need to create one of these harmful algal bloom forecasts?

ALLISON ALLEN: HAB forecasts rely on a range of different data types. Because there's such regional difference in HAB characteristics, forecasts are really tailored to best address the issues of concern in a particular location from the information they provide to the science and the tools used to develop that forecast. For instance, in the Gulf of Mexico, ocean color is a really important component to the forecasts while in the Northeast, sea surface temperature plays a larger role as an indicator.

But in general, the type of data we use includes satellite imagery, field observations such as samples, glider data, oceanographic and atmospheric monitoring platforms such as buoys or surface current mapping technology to help us determine the location, extent, and potential for development or movement of the bloom. We also rely on a range of models and forecasts such as wind forecasts or models of transport.

HOST: And what kind of information does a forecast provide?

ALLISON ALLEN: Our HAB forecasts, which are issued as bulletins, include information on forecasted conditions for the next three to seven days depending on whether there's an active bloom underway including information on potential or confirmed HAB events, chlorophyll levels, and the forecasted winds. The bulletins also provide forecasts for potential human impacts associated with confirmed blooms, it also provides information on the bloom size, movement, intensification, and the potential for bloom formation.

So there's different sections of the forecast that we provide. There's public conditions that are geared more towards the public, focusing on those potential health impacts while a more in-depth analysis provides the detailed information on the likely changes in the bloom over the next few days such as changes in the intensity of the event or the extent, which is more helpful for informing necessary actions such as monitoring.

HOST: That's all for today's Ocean Shorts. Thanks for joining us! For more information on forecasting harmful algal blooms, see our show notes for links. Be sure to tune in for the next episode.

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