North Temperate Lakes LTER: High Frequency Data: Meteorological, Dissolved Oxygen, Chlorophyll, Phycocyanin - Lake Mendota Buoy 2006 - current

The instrumented buoy on Lake Mendota is equipped with a dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are collected every minute. Hourly and daily averages for water temperatures are derived from the high resolution data. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface. In 2006, the thermistors were placed every 0.5 m from the surface through 7m and every 1m from 7m to 15m. In 2007 and 2008, the thermistors were placed every 0.5 m from the surface through 2m and every 1m from 2m to 20m. Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, photosynthetically active radiation (PAR), and barometric pressure. Not all sensors are deployed each season. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. The instrumented buoy was deployed in Lake Mendota in 2006 from June 27 to October 17. In 2007, from May 18 to October 29. In 2008, from 26 Jun to 14 Nov. In 2009, the buoy was deployed from April 17 to Nov 23. In 2009+, the Mendota buoy was located at 43.0995, -89.4045. 2017 notes: the buoy was deployed from Apr 22 to November 13. A boating mishap caused the loss of the air temp, humidity, and wind sensors between May 28 and July 11. The dissolved oxygen sensor had significant biofouling from algae and at least one zebra mussel during the year. In 2018 the buoy was deployed from April 11 to November 15. The dissolved oxygen sensor was a PME MiniDOT logger, having replaced a D-Opto sensor that was used since 2006. In 2019, the buoy was operating from April 16 to November 6th. A YSI Exo2 sonde was added to the buoy including dissolved oxygen (replacing the D-Opto), chlorophyll, phycocyanin, specific conductance, pH, fdom, and turbidity sensors. The chlorophyll and phycocyanin sensors are replacing older Turner sensors used in previous years. Both sets output RFU, but have a significant difference in magnitude. The YSI pH, DO, and specific conductance sensors were cleaned and calibrated about every two weeks. The sampling frequency is one minute. Number of sites: 1