Remote Sensing Post by PLL Team Member Robert Jacobsen

Rob Jacobsen

Rob Jacobsen

Field observations and sample collection at Laguna Negra offers lots of useful scientific data for the PLL team. However, some places around Laguna Negra are inaccessible because of steep terrain and distance from base camp. PLL remote sensing uses cameras on the ground and in space to fill gaps and better complete the information about the Laguna Negra system.

One area of particular interest for the PLL remote sensing team is the influence of geology around Laguna Negra. Laguna Negra is surrounded by many volcanic and plutonic igneous rocks, such as basalt and granite. These rocks weather and erode to form smaller pieces and new compositions. Some compositions are useful nutrients for lake organisms. PLL remote sensing uses a technique called reflectance spectroscopy, which measures the unique radiation signatures of different rock compositions. At Laguna Negra, a reflectance spectrometer measures rock compositions near base camp. These measurements are then compared with satellite spectroscopy data to understand geologic compositions around the lake.

Although reflectance spectroscopy indicates which rock compositions surround Laguna Negra, it does not explain how such material enters the lake. PLL remote sensing uses thermal imaging to study the transportation of rocks and minerals into Laguna Negra. From base camp, a thermal camera measures hillside temperature changes over a 24-hour period. Surfaces with different rock grain sizes and vegetation will have different temperatures throughout the day – sands heat up early in the morning, while boulders stay cold until the afternoon. This property is called thermal inertia. Measurements of relative thermal inertia, along with surface slope angles, indicate which fine grain material is most likely to enter Laguna Negra. Combining this information with composition data from reflectance spectroscopy helps the PLL remote sensing team model the input of geologic material around Laguna Negra. Such information helps other team members understand the interactions between lake biology and lake geology.

Team: Jeff Moersch (Co-I), Robert Jacobsen (Graduate Student Team Member), Matt Smith (Graduate Student Field Assistant) University of Tennessee


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