Yellowstone Lake is not only largest high altitude (above 7000 ft) freshwater lake in the US, it is an active part of the Yellowstone Caldera. As part of a major NSF funded study, supported by UNAVCO(www.unavco.org), to examine and "understand how earthquakes, volcanic processes, and climate affect the hydrothermal system located beneath Yellowstone Lake", the HD-YLAKE project (hdylake.org), a semi-permanent water pressure/depth gauge was installed near the Grant Village dock to record lake levels at frequencies of one minute or greater. While the average lake level is controlled by water flux into the system via precipitation (rain and snow melt) and discharge via the Yellowstone River, short term variations are driven by the resonance of the lake basin and kinetic energy imparted on the system via atmospheric and, possibly, thermal inputs (Mencin et. al, 2010). The resulting oscillations, generally known as seiches, can be used to study the surrounding environment (Luttrell et. al 2010).
The lake level presented here, in cm of water, is related to an arbitrary benchmark on the Grant Boat dock and in ft related to the Bridge Bay nominal water surface. (There are plans to formally survey this in and relate it to the long term record obtained at Bridge Bay, in units related to the nominal water surface, the current Bridge Bay datum is via a best fit transfer function with only one month of data). The sensor was installed on 2017-06-28. The sensor is a Paros Scientific 8WD Series 8000 Intelligent Depth Sensor, the data has been corrected for barometric pressure concurrently collected at the station and offset approximately 611 cm from the sensor. There is no temperature correction for water density. There are temperature corrections used in the pressure gauge to illict a linear response. The seiches are clearly evident in the signal at all observed times, reflecting an unusually high-Q system. One of the aims of this study is to understand why this system is so persistent. The principal period of the seiche (mode=1) is approximately 76 minutes with amplitudes as large several tens of centimeters. See the About page for a more through explanation. NOTE: The offset on 27-July-2017 was introduced when switching to a local barometric pressure gauge from one that was proximally located about 200 m distant and 30 m higher. For more information please see the About page or contact Dave Mencin: [email protected] |