Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study helps satellites measure Great Lakes’ water quality

26.05.2004


Ohio State University engineers are helping satellites form a clearer picture of water quality in the Great Lakes.


NASA’s Seastar Satellite



The study -- the first ever to rate the effectiveness of various computer models for monitoring the Great Lakes -- might also aid studies of global climate change.

As algae flourishes in the five freshwater lakes every summer, satellite images show the water changing color from blue to green, explained Carolyn Merry, professor of civil and environmental engineering and geodetic science.


When algae levels are too high, water takes on a foul taste and odor that isn’t easily removed by traditional treatment methods. Some forms of algae, such as one called microcystis, are toxic when consumed in large quantities. Though it can be filtered out of drinking water, microcystis can kill fish and birds, and coastal communities often have to ban swimming and water skiing in the summer when the algae blooms.

Computer models enable scientists to measure the color of light reflected from the water to gauge how much algae is present in a lake, and where. The problem: all the available models of this type were originally designed for sea water, not lake water.

"They’ve got it down pat for the ocean," Merry said of the various models developed by NASA and other agencies over the years. "But lakes are shallower and have different water conditions that affect the wavelengths of light collected by the satellites, so we can get erroneous measurements."

Merry and master’s degree student Raghavendra Mupparthy reported the results of an initial study of Lake Erie May 25 in Denver at the meeting of the American Society for Photogrammetry & Remote Sensing. They determined which four of the top ocean models may perform well for studies of the Great Lakes.

Most scientists look for evidence of climate change in the oceans rather than in lakes, but that may change in the future, the engineers said.

"Lakes are important because they respond much faster to climate change than oceans do," Mupparthy said.

Erie is the warmest of the Great Lakes, the shallowest and richest in life, and has changed much in recent years. For instance, the lake has experienced a microcystis outbreak every summer since 1995. The warmer the temperature, the bigger the outbreak, Merry said.

Though lakeside towns routinely measure algae levels firsthand, satellite images give scientists a broader view of trends in the lakes.

"If we want to really understand whats happening in Lake Erie, we can take these computer models and marry them to other data to get a more complete picture," Merry said.

The models could also apply to other large lakes and seas, such as the Mediterranean.

The key to proving the models valid, she said, is to compare them to actual measurements of algae in the water. Thats what she and Mupparthy did for Lake Erie, by collecting water samples from four sites in October 2000.

They compared the actual algae levels to the levels suggested by 17 different models, each using images of the lake taken by NASA’s SeaStar spacecraft.

Model performance varied widely; one demonstrated an error of more than 250 percent, while several were off by less than one percent.

What set the top-performing models apart was how well they enabled the engineers to remove the interference of atmospheric molecules. Over the ocean, carbon dioxide, ozone, and humidity are fairly constant, but amounts of these molecules fluctuate dramatically over lakes depending on the weather and human activity.

The National Oceanic and Atmospheric Administrations Cooperative Institute for Limnology and Ecosystems Research funded this study. Merry and Mupparthy have applied for funding to collect water samples from more sites, with the hope of customizing a model for Lake Erie.


Contact: Carolyn Merry, (614) 292-6889; Merry.1@osu.edu
Raghavendra Mupparthy, (614) 688-4753; Mupparthy.1@osu.edu

Pam Frost Gorder | Ohio State University
Further information:
http://researchnews.osu.edu/archive/lakeview.htm

More articles from Earth Sciences:

nachricht Less radiation in inner Van Allen belt than previously believed
21.03.2017 | DOE/Los Alamos National Laboratory

nachricht Mars volcano, Earth's dinosaurs went extinct about the same time
21.03.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>