Warning of Detrimental Algae: NASA Utilizes New TROPOMI Instrument for Monitoring Algal Outbreaks

Warning of Detrimental Algae: NASA Utilizes New TROPOMI Instrument for Monitoring Algal Outbreaks

An image of Florida’s southern extremity curving into a cerulean sea, framed by wisps of clouds, was recently taken by NASA’s MODIS sensor. MODIS, along with a new generation of satellite technology, assists environmental regulators in keeping tabs on harmful algae not just along the Gulf Coast but also in other areas. Credit: NASA

Detrimental algal blooms present risks to public health, marine ecosystems, and various economic sectors including tourism and fishing. Emerging advancements in satellite imaging technology are offering novel perspectives on our oceans teeming with life.

In the year 2020, catastrophic algal blooms on Florida’s western coastline resulted in approximately 2,000 tons of marine mortality in the Tampa Bay area. The adverse impact on human health was also significant, including a notable uptick in asthma cases in Sarasota and Pinellas counties, with an estimated economic toll approaching $1 billion across diverse sectors.

Satellite-Based Identification of Algal Outbreaks

For years, satellites in Earth’s orbit have been employed to detect algal blooms from a celestial vantage point, facilitating more extensive and frequent monitoring compared to direct water sampling. Traditional monitoring methods primarily rely on visible spectrum measurements of ocean color, albeit limited to cloud-free conditions.

A paper recently published in Geophysical Research Letters, spearheaded by researchers from NASA’s Jet Propulsion Laboratory (JPL) in Southern California, reveals how the TROPOMI (TROPOspheric Monitoring Instrument) was capable of discerning crucial information about Karenia brevis (or K. brevis), the microscopic algae responsible for the 2020 outbreaks, even through thin cloud layers.

TROPOMI’s superior capacity to detect and quantify narrow light wavelengths could greatly enhance the predictive and management capabilities of both federal agencies and local communities. TROPOMI is an onboard instrument on the European Sentinel 5P spacecraft, which was launched in 2017.

K. brevis and Florida’s West Coast

The focus of the study was the West Florida Shelf, an expansive continental crust extending from the Panhandle to the Keys. Originating from different parts of the Gulf of Mexico, K. brevis is transported towards the shore by strong winds and currents. Recent findings suggest that Western Florida, like many other coastal regions, might be increasingly susceptible to outbreaks due to a combination of nutrient-rich, warm conditions, accelerated by factors like runoff, fertilizers, and climate change.

Monitoring Frameworks and Perils Associated with K. brevis

Systems to monitor and forecast harmful algal blooms are operational in multiple states and coastal regions, including the Gulf of Mexico and the Great Lakes. The National Oceanic and Atmospheric Administration (NOAA) collaborates with educational, state, tribal, and local organizations to create and disseminate algal bloom forecasts akin to meteorological forecasts.

K. brevis episodes are particularly alarming due to their production of a powerful neurotoxin that, in elevated concentrations, can result in massive fish mortalities and affect other marine organisms including turtles, manatees, and birds. Humans exposed to this toxin can suffer respiratory issues, and it can also accumulate in shellfish, causing gastrointestinal disorders in consumers.

Satellite-Based Detection Techniques

When subjected to photosynthesis, K. brevis emits a faint red light called solar-induced fluorescence (red SIF), which certain satellite instruments like TROPOMI—originally designed to monitor air pollution—can detect. Analysis of TROPOMI data gathered between 2018 and 2020 along Western Florida’s coast revealed that the instrument collected nearly double the fluorescence data compared to older methods relying on ocean color.

Space-Age Surveillance

Researchers contend that their discoveries underline the merits of utilizing TROPOMI either independently or in combination with long-established Earth-monitoring instruments such as NASA’s MODIS, which is currently being used by environmental stewards in Florida and elsewhere to identify algal blooms during clear skies.

An additional ocean color sensor, scheduled for a 2024 launch, aims to revolutionize our understanding of marine ecosystems. NASA’s PACE mission will explore ocean biology, atmospheric particles, and cloud formations in a broader range of wavelengths than its predecessors, thereby aiding in the prediction of detrimental algal outbreaks and fluctuations in fish populations, among other factors influencing commercial and recreational industries.

According to lead author Kelly Luis, a NASA postdoctoral program fellow at JPL, “The use of TROPOMI’s red SIF technology signifies an enhancement in early warning systems that can function beyond optimal weather conditions.”

Recent case studies funded by NASA have demonstrated that preemptive satellite detection offers tangible benefits. For instance, early identification of cyanobacteria in Utah Lake resulted in considerable economic savings related to healthcare, work hours, and other factors. An advanced warning of a few days can lead to immediate remedial actions, including dissemination of public notices and potential beach closures.

Reference: “Initial Demonstration of Red Solar-Induced Fluorescence for Monitoring Detrimental Algal Blooms” by Kelly Luis, Philipp Köhler, Christian Frankenberg and Michelle Gierach, 10 July 2023, Geophysical Research Letters.
DOI: 10.1029/2022GL101715

Frequently Asked Questions (FAQs) about TROPOMI satellite monitoring

More about TROPOMI satellite monitoring

• NASA’s TROPOMI Instrument Overview
• Geophysical Research Letters Journal
• National Oceanic and Atmospheric Administration (NOAA) Algal Blooms Monitoring
• NASA’s PACE Mission Overview
• Economic Impact of Algal Blooms on Florida’s West Coast
• Case Study on Early Detection of Cyanobacteria in Utah Lake
• Health Risks Associated with Harmful Algal Blooms
• Overview of Satellite Imaging in Environmental Monitoring