The Yellow Submarine
The Autonomous Underwater Vehicle (AUV) pictured is the property of Purdue University Professor Cary Troy. On its maiden launch October 2nd and its first "unmanned" one-hour voyage October 27th Prof. Troy was very nervous and very excited. The remote controlled submersible has been some four years in the making and cost approximately $80,000 to build to the exact specifications required. Test prototypes have been used by the U.S. Navy in operations such as mine detections.
Besides Troy, who is an Assistant Professor of Civil Engineering in Purdue's Hydraulics & Hydrology group, the only other entity using a commercial model AUV is the United States Geological Survey in Illinois. Prof. Troy's long-range project is based at Lake Michigan, but rough waters there led to his move to Lake Maxinkuckee for equipment and computer modeling testing.
In the fall of 2007, Lake Maxinkuckee Environmental Council (LMEC) member Gary Shaffer assisted Prof. Troy and his interns in placing a thermistor line in the lake; that is, a buoy with air temperature sensors on top and a line into the water with 20 thermistors - which measure water temperature - spaced several feet apart and taking temperature readings every ten seconds. A similar experiment is being conducted this fall/winter and includes a weather station placed at the edge of the lake that will record wind speeds and air temperatures to coordinate with the water temperature data. Pictured is a one-dimensional graph developed with last season's readings that actually shows what is known as the "Fall Flip," the day when the water temperature - from top to bottom - is the same. Cold water is heavier than warm water, so as temperatures begin to equal out there is actually a "turnover" action that takes place. That minute, or day, is shown by the yellow band on the graph. Prof. Troy is working on developing a three-dimensional computer model as his experiments progress.
LMEC Chair Allen Chesser agrees with Troy that the plethora of useful information on the AUV will likely supply all parties involved. "This provides information to us on water temperature changes during the four seasons," explains Chesser. "This will also provide us with information on water movement from the lower part of the lake as it moves to the surface. The Environmental Council has been concerned about oxygen levels and dissolved phosphates underneath Lake Maxinkuckee so we can better understand deposits at the bottom, and our future concerns."
One facet of this study that is of major interest to the LMEC involves what happens when the "Fall Flip" occurs. Is that turnover action from bottom to top actually redistributing phosphorous deposits we assume are collecting on the lake bottom? We know that even with the Wilson, Curtiss and Kline wetlands that we built to "slow" the phosphorous loading from some sources, phosphorous is still entering the lake. In addition to the work with Prof. Troy, the LMEC Board is considering engaging JF New, a premier ecological consulting company, to take multiple core samplings of the lake bottom. These samples would then be sent to the laboratory of Prof. Bill Jones at Indiana University for chemical and gas testing. Correlating this data to Prof. Troy's thermocline studies would provide determinates that could influence future project efforts of the LMEC.
(Article courtesy of the Lake Maxinkuckee Environmental Council)