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门多塔湖（Lake Mendota）上的传感器浮标搭载了溶解氧传感器、热敏电阻链以及气象传感器，可提供湖泊热结构、气象条件与湖泊代谢的基础观测数据。数据采集频率为每分钟1次。基于该高分辨率原始数据，可导出水温的逐小时及逐日平均值。D-Opto溶解氧传感器距湖面0.5米。 2006年，热敏电阻的布设间距为：表层至7米水深范围内每0.5米布设1个，7米至15米水深范围内每1米布设1个。2007年与2008年，热敏电阻的布设间距调整为：表层至2米水深范围内每0.5米布设1个，2米至20米水深范围内每1米布设1个。 气象传感器可测定风速、风向、相对湿度、气温、光合有效辐射（photosynthetically active radiation, PAR）与大气压力。并非每个观测季都会布设全部传感器。 在校正了大气界面的气体通量以及水柱内的垂直混合效应后，二氧化碳、氧气等溶解气体的高频监测数据可用于估算总初级生产力、呼吸作用与生态系统净生产力——这三者是完整湖泊代谢的核心组成部分。 该传感器浮标的布放时段如下：2006年6月27日至10月17日；2007年5月18日至10月29日；2008年6月26日至11月14日；2009年4月17日至11月23日。2009年及之后，门多塔浮标的布设坐标为43.0995，-89.4045。 2017年备注：浮标布放时段为4月22日至11月13日。5月28日至7月11日期间，一起船只作业意外事故导致气温、湿度与风速传感器丢失。该年度内，溶解氧传感器因藻类附着及至少1只斑马贻贝滋生，出现严重生物污损。 2018年，浮标布放时段为4月11日至11月15日。本次使用的溶解氧传感器为PME MiniDOT记录仪，替代了自2006年起启用的D-Opto传感器。 2019年，浮标运行时段为4月16日至11月6日。本次浮标新增了YSI Exo2多参数水质探头，集成了溶解氧传感器（替代原D-Opto传感器）、叶绿素传感器、藻蓝蛋白传感器、比电导率传感器、pH传感器、荧光溶解有机物（fdom）传感器以及浊度传感器。原有叶绿素与藻蓝蛋白传感器替换了往年使用的Turner品牌传感器。两类传感器均以相对荧光单位（Relative Fluorescence Unit, RFU）为输出单位，但数值幅度存在显著差异。YSI品牌的pH、溶解氧及比电导率传感器约每两周清洁校准一次。数据采样频率为每分钟1次。监测点位数量：1个。