Looking at lakes
7 Jun 2004
Environmental scientists around the world agree that the climate is changing, but one of the areas they don't all agree on is the best way to monitor it.
One common method is to look at the state of the oceans - their temperature, and the quality of the water, can provide evidence of changing conditions. However, engineers at Ohio State University in Columbus believe that smaller bodies of water might provide better information.
The team is looking at algae levels in the Great Lakes. 'Lakes are important, because they respond much faster to climate change than oceans do,' explains Raghavendra Mupparthy, a graduate student on the project, which is led by Carolyn Merry, professor of civil and environmental engineering and geodetic science.
Sea conditions are monitored by satellite, using computer models to interpret data from light readings to show where algal blooms might be forming. According to Merry, methods for monitoring lakes are somewhat behind the science for oceans.
'Lakes are shallower and have different water conditions that affect the wavelengths of light collected by the satellites, so we can get erroneous measurements,' she says.
Merry's team is looking at Lake Erie, the warmest, shallowest and richest in life of the Great Lakes. The lake has experienced an outbreak of a toxic alga called microcystitis every year since 1995, and they seem to be becoming more severe. To help study this trend, Merry's team has determined which software tools give the most accurate results for lake conditions.
Some of the software models were more than 25% out, when compared to readings taken from the lake itself. The best models remove the interference of atmospheric molecules such as carbon dioxide, ozone and humidity, which are constant over the oceans but can vary widely over lakes.
The results of these were accurate to within 1%, the team says. Such models could be applied to large lakes or small seas, such as the Mediterranean.
