BATON ROUGE – Having accurate, accessible, real-time oceanic and atmospheric information available prior to, during and following catastrophic events has a significant impact on a community’s ability to save lives, property and ecosystem function.
Two LSU College of the Coast & Environment labs have expertise in acquiring this information: the Earth Scan Laboratory, or ESL, and the Wave-Current Information System, or WAVCIS, provide a wealth of critical environmental measurements both above and below the Gulf of Mexico’s surface.
ESL uses three antennas on the roof of the Howe-Russell Geoscience Complex at LSU to capture satellite measurements and imagery of the Gulf region. The lab uses polar orbiting and geostationary satellites that detect a variety of wavelengths, such as infrared radiation, to quantify sea surface temperature, circulation changes, water quality and sediment distribution and transport.
The satellites can also identify areas of flooding and algal blooms that occur in Louisiana’s lakes, bays and along the coast.
While ESL observes the Gulf from above, WAVCIS looks at what lies beneath the surface of the water. WAVCIS is a monitoring program that provides a range of real-time data including wind, air pressure, tide, storm surge and wave height off the Louisiana coast.
The information collected from these two labs has a variety of real-world uses. One example is that ESL can detect chlorophyll, enabling the tracking of algal phytoplankton blooms, which can be toxic to humans and shellfish, in the imagery collected from NASA’s Moderate-resolution
Imaging Spectroradiometer, or MODIS-equipped satellites. MODIS acquires information in 36 spectral bands, including infrared for temperature and blue and green channels that detect chlorophyll. High concentrations of chlorophyll in phytoplankton can lead to hypoxia in bottom waters, a phenomenon where the concentration of dissolved oxygen in water decreases until it can no longer support living aquatic organisms. In fact, the second largest hypoxic zone in the world is in the northern Gulf of Mexico on the Louisiana/Texas continental shelf.
ESL also monitors deep water currents, such as the Loop Current that flows northward from Cuba toward the Bird’s foot delta in the northern Gulf of Mexico. High-velocity currents within eddies from the Loop Current can disrupt oil collection on deep water platforms in the Gulf.
Monitoring and predicting these currents can help oil and gas companies to better protect their people and equipment. In addition, cyclonic frontal eddies along the Loop Current’s margin create upwellings of nutrient-rich waters that attract pelagic fish, such as tuna and swordfish, to spawn—valuable information for the fishing industry.
While ESL collects deep water current information, WAVCIS investigates subsurface coastal currents vital to protecting the Louisiana coastline from unexpected storm surges. Unlike ESL satellites, which monitor a large swath of the Gulf above the surface, WAVCIS stations use Acoustic Doppler Current Profilers, or ADCPs, to take vertical profiles of fixed points in the water and measure water flow velocity.
This information is transmitted back to the lab and relayed through the Internet to the Gulf of Mexico Coastal Ocean Observing System every hour.
ADCPs send out an acoustic signal through the water column and receive a reflective signal back to the receiving sensor.
The length of time it takes for the sound to reach the sensor indicates its depth in the water. The longer it takes, the further away it is from the sensor.
“In addition, with the calculation of what we call a Doppler shift in frequency, the velocity of the water can be estimated. By these calculations, the ADCPs can give you a profile of the velocity of the water,” said Chunyan Li, program director of WAVCIS at LSU.
These point measurements can be used as stand-alone data for analyses, or used for numerical models to predict conditions throughout the entire area. This information can be used by National Oceanic and Atmospheric Administration and other researchers to predict the behavior of tides, waves and storm surges from an oncoming hurricane, important information for communities along the coast to determine when to evacuate and how to anticipate the extent of property damage.
Earth Scan Lab’s satellite measurements and WAVCIS’s acoustic profiles serve as the eyes and the ears of the Gulf. They provide critical real-time information to disaster management agencies as well as valuable archival data to educate students, researchers and the public about Louisiana’s dynamic coast.