US Long-Term Ecological Research Network

North Temperate Lakes LTER: Physical Limnology of Lake Kegonsa and Lake Waubesa 1995 - current

Abstract
Parameters characterizing the physical limnology of Lakes Waubesa and Kegonsa are measured at one station in the deepest part of each lake at 0.5-m to 1-m depth intervals. Measured parameters in the data set include water temperature and dissolved oxygen, as well as the derived parameter percent oxygen saturation.Number of sites: 2. Sampling Frequency: bi-weekly during ice-free season from late March or early April through early September, then every 4 weeks through late November; sampling is conducted usually once during the winter (depending on ice conditions).
Dataset ID
264
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
G. Reading Temperature and Dissolved Oxygen 1. Before leaving to sample a lake, check to make sure that there are no air bubbles under the probe membrane of the YSI TemperatureorDissolved Oxygen meter. If there are air bubbles or if it has been several months since changing the membrane (or if the instrument does not calibrate well or the oxygen readings wander), change the membrane as explained in the manual. Note: We have always used the Standard membranes. If adding water to new membrane fluid bottle (KCl), make sure to add Milli-Q water and not the CFL distilled water. 2. Be sure to always store the probe in 100percent humidity surrounded by a wet sponge or paper towel. 3. Turn on the temperatureordissolved oxygen meter at least 30 minutes before using it. It is best to turn it on before leaving to sample a lake as it uses up batteries slowly. 4. Calibrate the meter using the chart on the back of the instrument (adjusted to the Madison altitude - 97percent oxygen saturation). Leave the plastic cap on the probe (at 100percent humidity). The temperature should not be changing during the calibration. Zero the instrument. When the temperature equilibrates, adjust the oxygen to correspond to the chart. After calibrating the instrument, switch the knob to percent oxygen saturation to make sure it is close to 97percent. 5. Take readings at 1 meter intervals making sure to gently jiggle the cord when taking the oxygen readings (to avoid oxygen depletion). Jiggling the cord is not necessary if using a cable with a stirrer. Take half meter readings in the metalimnion (when temperature andoror oxygen readings exhibit a greater change with depth). A change of temperature greater than 1degreeC warrants half-meter intervals. 6. Record the bottom depth using the markings on the temp.oroxygen meter cord and take a temperature and dissolved oxygen reading with the probe lying on the lake bottom. Dont forget to jiggle the probe to remove any sediment. 7. If any readings seem suspicious, check them again when bringing the probe back up to the surface. You can also double check the calibration after bringing the probe out of the water (and putting the cap back on).
Short Name
KEWAPH01
Version Number
22

North Temperate Lakes LTER: Physical Limnology of Primary Study Lakes 1981 - current

Abstract
Parameters characterizing the physical limnology of the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish) are measured at one station in the deepest part of each lake at 0.25-m to 1-m depth intervals depending on the lake. Measured parameters in the data set include water temperature, vertical penetration of photosynthetically active radiation (PAR; not measured on lakes Mendota, Monona, Wingra, and Fish), dissolved oxygen, as well as the derived parameter percent oxygen saturation. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season for the northern lakes. The southern lakes are similar except that sampling occurs monthly during the fall and typically only once during the winter (depending on ice conditions). Number of sites: 11
Core Areas
Dataset ID
29
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Light (PAR) extinction coefficient is calculated by linearly regressing ln (FRLIGHT (z)) on depth z where the intercept is not constrained. FRLIGHT(z) = LIGHT(z) or DECK(z) where LIGHT(z) is light measured at depth z and DECK(z) is light measured on deck (above water) at the same time. For open water light profiles, the surface light measurement (depth z = 0) is excluded from the regression. For winter light profiles taken beneath the ice, the first light data are taken at the bottom of the ice cover and are included in the regression. The depth of uppermost light value is equal to the depth of the ice adjusted by the water level in the sample hole, i.e., the depth below the surface of the water. The water level can be at, above or below the surface of the ice. If the water level was not recorded, it is assumed to be 0.0 and the calculated light extinction coefficient is flagged. If ice thickness was not recorded, a light extinction coefficient is not calculated. For light data collected prior to March, 2007, light values less than 3.0 (micromolesPerMeterSquaredPerSec) are excluded. For light data collected starting in March 2007, light values less than 1.0 (micromolesPerMeterSquaredPerSec) are excluded. Except for bog lakes before August 1989, a light extinction coefficient is not calculated if there are less than three FRLIGHT values to be regressed. For bog lakes before August 1989, a light extinction coefficient is calculated if there are least two FRLIGHT values to be regressed. In these cases, the light extinction coefficient is flagged as non-standard. FRLIGHT values should be monotonically decreasing with depth. For light profiles where this is not true, a light extinction coefficient is not calculated. For samples for which light data at depth are present, but the corresponding deck light are missing, a light extinction coefficient is calculated by regressing ln (LIGHT (z)) on depth z. Note that if actual deck light had remained constant during the recording of the light profile, the resulting light extinction coefficient is the same as from regressing ln(FRLIGHT(z)). In these cases, the light extinction coefficient is flagged as non-standard. Oxygen and Temperature: We sample at the deepest part of the lake, taking a temperature and oxygen profile at meter intervals from the surface to within 1 meter of the bottom using a YSI Pro-ODO temporDO meter. We sample biweekly during open water and approximately every five weeks during ice cover. Protocol Log: Prior to 2011, we used a YSI Model 58 temporDO meter.
Short Name
NTLPH01
Version Number
28

North Temperate Lakes LTER Meteorological Data - Woodruff Airport 1989 - current

Abstract
Meteorological measurements are being gathered at a site at the Noble F. Lee municipal airport located at Woodruff, WI for three purposes: 1) to supplement the data from the raft on Sparkling and Trout Lakes used for evaporation calculations, and 2) to provide standard meteorological measurements for the North Temperate Lakes site, and 3) to measure radiation for primary production studies in the study lakes at the site. The following parameters are measured at 1-minute intervals: 1) air temperature at 1.5 m above ground, 2) relative humidity at 1.5 m above ground, 3) wind speed and direction and peak wind speed at 3 m above ground, 4) total long-wave radiation, 5) total short-wave radiation, 6) photosynthetically active radiation (PAR), 7) total solar radiation, and 8) total precipitation. High resolution data is taken typically at 10 minute intervals as well as 1-hour and 24-hour averages. Half-hourly averages of PAR and shortwave radiation are also stored. Precipitation data are summed for 5-minute intervals during periods of detectable precipitation. Derived data included in this data set include dew point temperature and vapor pressure as well as daily minimum and maximum values for some parameters. Data are automatically updated into the database every six hours. Sampling frequency: varies for instantaneous samples; averaged to hourly, half-hourly and daily values. Number of sites: 1. Date/time is Central Standard Time (GMT - 06:00) throughout the year.
Dataset ID
17
Date Range
-
Metadata Provider
Methods
See abstract for methods.
Short Name
NTLME01
Version Number
33

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Sparkling Lake Raft 1989 - current

Abstract
The instrumented raft on Sparkling Lake is equipped with a dissolved oxygen and CO2 sensors, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity ( at 1, 2, and 3 m heights; but beginning in 2008, only at 2 m) ,and water temperatures (from thermistors placed throughout the water column at intervals varying from 0.5 to 3m) are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates. 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. Other parameters measured include precipitation, wind direction (beginning in 2008), and barometric pressure (beginning in 2008). Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min. Number of sites: 1
Core Areas
Dataset ID
4
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented raft on Sparkling Lake is equipped with a D-Opto dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity ( at 1, 2, and 3 m heights; but beginning in 2008, only at 2 m) ,and water temperatures (from thermistors placed throughout the water column at intervals varying from 0.5 to 3m) are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates. 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. Other parameters measured include precipitation, wind direction (beginning in 2008), and barometric pressure (beginning in 2008). Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min.Dissolved oxygen sensors: 2004-2006: Greenspan Technology series 1200; 2007-2016: Zebra-Tech Ltd. D-Opto; 2018+: OTT HydrolabCO2 sensors: 2018+: ProOceanos MiniCO2 for dissolved CO2; Eosense Inc. eosGP for atmospheric CO2
Short Name
NTLEV01
Version Number
33

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

Abstract
The instrumented buoy on Lake Mendota is equipped with limnological 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 are derived from the high resolution (1 minute) data. Hourly and daily values may not be current with high resolution data as they are calculated at the end of the season.

Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, and photosynthetically active radiation (PAR). Not all sensors are deployed each season. A list of sensors used since the first deployment in 2006 is provided as a downloadable CSV file.

Number of sites: 1. Location lat/long: 43.0995, -89.4045

Notable events:
2017 - A boating mishap caused the loss of air temperature, relative humidity, and wind sensors between May 28 and July 11. The dissolved oxygen sensor had significant biofouling from algae and zebra mussels.
2019 - A YSI EXO2 sonde was added to the buoy and includes DO, chlorophyll, phycocyanin, specific conductance, pH, fDOM, and turbidity sensors. The chlorophyll and phycocyanin sensors replace Turner Cyclops 7 fluorometers that had been in use in prior years. Both sets of sensors output RFU, but have significant magnitude differences. The YSI pH, DO, and specific conductance sensors were cleaned and recalibrated every two weeks.
2020 - Cleaning and calibration of the YSI sensors occurred nearly every week. The dissolved CO2 sensor was not operating between July 2 and September 17.


Core Areas
Dataset ID
129
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
See abstract for methods description
Short Name
MEBUOY1
Version Number
32

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Trout Lake Buoy 2004 - current

Abstract
The instrumented buoy on Trout Lake 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 usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface. Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, photosynthetically active radiation (PAR), and barometric pressure. Starting in 2005, thermistors were placed every 0.5-1m from the surface through 14m and every 2 to 4m from 14m to the bottom of the water column at 31m. In July 2006, a new thermistor chain was deployed with thermistors placed every meter from the surface through a depth of 19 meters. 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. Data are averaged to daily values from one minute samples for years 2005 - 2006. Daily values are computed from high resolution data starting in year 2007. Data are averaged to hourly values from one minute samples for years 2005 - 2008, Hourly values are computed from high resolution data starting in year 2009. Hourly and daily values may not be current with high resolution data in the current year. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples Number of sites: 1
Core Areas
Dataset ID
117
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented buoy on Trout Lake 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 usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface. Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, photosynthetically active radiation (PAR), and barometric pressure. Starting in 2005, thermistors were placed every 0.5-1m from the surface through 14m and every 2 to 4m from 14m to the bottom of the water column at 31m. In July 2006, a new thermistor chain was deployed with thermistors placed every meter from the surface through a depth of 19 meters. 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. Data are averaged to daily values from one minute samples for years 2005 - 2006. Daily values are computed from high resolution data starting in year 2007. Data are averaged to hourly values from one minute samples for years 2005 - 2008, Hourly values are computed from high resolution data starting in year 2009. Hourly and daily values may not be current with high resolution data in the current year. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples
Short Name
TRBUOY1
Version Number
40
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