In the News
Leif Olmanson (co-authors, Patrick Brezonik, Marvin Bauer, and Jacques Finlay) presented “Regional Water Quality Measurements of Optically Complex Inland Waters Using New Enhanced Landsat 8 and Sentinel 2 Imagery” at the Pecora 20 Conference and was interviewed on Monitoring Minnesota lakes with Landsat Data for the USGS Landsat in Action video series.
Research Associate Leif Olmanson (P.I.) has received a new two-year contract from the Minnesota Pollution Control Agency that will map lake water clarity statewide for two periods: 2010 and 2015. The project will enable updating our semi-decadal database that currently contains satellite-based water clarity results (reported as Secchi depth) for more than 10,000 Minnesota lakes in each of seven periods starting in 1975. The new grant also provides funds to update the LakeBrowser that is used to access the water clarity data.
This past summer was a very active time for our group gathering field data and water samples to calibrate statewide imagery for CDOM, chlorophyll, suspended solids, turbidity, and Secchi depth for our NSF and LCCMR projects. The 2017 field program was designed to collect samples within a few days following acquisitions of clear imagery by Sentinel-2.
We sampled 230 sites, from Hayes Lake in northwestern Minnesota and many lakes near Ely, MN to lakes within miles of the Iowa border. Claire Griffin, postdoctoral associate, led field coordination and sampling efforts with help from field teams that included three undergraduates, three technicians (recent graduates), two graduate students, and several Co-PIs. We also collaborated with researchers in the Cotner Lab at UMN, Lesley Knoll at the Itasca Biological Station, the Red Lake Nation DNR, Minneapolis Parks Board, Minnesota Science Museum St. Croix Research Lab, and volunteers from Brainerd and Lake Vermillion, who helped us obtain samples across a much larger area than we would have been able to do alone – many thanks to them! Despite cloudy conditions early in the summer, imagery from August and September provides clear data to map chlorophyll-a, suspended solids, and CDOM across the state. Some photos from the summer field work.
Professor Ray Hozalski (Department of Civil, Environmental, and Geo-Engineering), an international expert on drinking water treatment processes and P.I. of our NSF grant on CDOM, gave an invited talk titled “Remote Sensing for Source Water Characterization” at a Gordon Conference on Drinking Water Disinfection Byproducts in early August. The week-long conference was held at Mount Holyoke College in South Hadley, Massachusetts, and the talk covered a broad range of topics involved in the NSF grant. According to Prof. Hozalski, the presentation was received enthusiastically by conference participants.
Our ongoing work on satellite-based measurement of colored dissolved organic matter (CDOM) was described on NASA’s, Earth Observatory website, on October 25, 2016, in an article titled Minnesota: Land of the Many-Colored Lakes. The article provides maps of colored lakes in northern Minnesota and describes the state as “Minnesota, the land of 10,000 lakes,” might as well be called the “land of 10,000 shades of lakes,” stating that “many of them owe their color to CDOM: colored dissolved organic matter.” Comments by Leif Olmanson and Patrick Brezonik are included in the article, which can be viewed at: https://earthobservatory.nasa.gov/IOTD/view.php?id=88971
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