This readme.txt file was generated on 2022-03-18 by Miki Hondzo Recommended citation for the data: Hondzo, Miki; You, Jiaqi; Taylor, Jackie. (2022). Measurement and Scaling of Lake Surface Skin Temperatures. Retrieved from the Data Repository for the University of Minnesota, https://doi.org/10.13020/ez62-cs46. ------------------- GENERAL INFORMATION ------------------- 1. Title of Dataset Measurement and Scaling of Lake Surface Skin Temperatures 2. Author Information Principal Investigator Contact Information Name: Miki Hondzo Institution: University of Minnesota Address: Department of Civil, Environmental and Geo-Engineering St. Anthony Falls Laboratory, Minneapolis, MN Email:mhondzo@umn.edu ORCID: 0000-0001-8871-8380 Associate or Co-investigator Contact Information Name: Jiaqi You Institution: Guangdong University of Technology Address: Institute of Environmental and Ecological Engineering, Guangzhou, China Email: youxx137@umn.edu ORCID: Associate or Co-investigator Contact Information Name: Jackie Taylor Institution: University of Minnesota Address: Department of Civil, Environmental and Geo-Engineering St. Anthony Falls Laboratory, Minneapolis, MN Email: tayl1562@umn.edu ORCID: 0000-0001-6253-2270 3. Date published or finalized for release: Hondzo, M.m You, J., J., Taylor, J., Bartlet, G., & Voller, V.R. (2022). Measurement and scaling of lake surface temperatures, Geophysical Research Letters, 49, e2021GL093226. https://doi.org/10.1029/2021GL093226 4. Date of data collection (single date, range, approximate date) 20180727 to 20180928 5. Geographic location of data collection (where was data collected?): Ramsey Lake (45˚12’27’’N, 93˚59’43’’W) is a residential and recreational lake located in Wright County in Minnesota, USA (Figure 1a). The lake has a surface area of 1.28 km2 and a maximum depth of 24.4 m with a mean depth of 6.5 m. In summer the lake has a stable thermal stratification and in May and November, of each year, the temperature through the lake depth is approximately uniform. 6. Information about funding sources that supported the collection of the data: No funding source 7. Overview of the data (abstract): A floating research station, designed and built at the St. Anthony Falls Laboratory (University of Minnesota), was deployed and anchored on Ramsey lake from July to October, 2018. The research station's measurement location had a water depth of 18.0 m, enabling temperature profiling through the epilimnion, metalimnion, and hypolimnion. The research station conducted synchronized monitoring of 1) wind speed and air temperature at 1.5 m above the water surface, and 2) water temperatures at twelve depths from 0.05 m to the bottom of the lake. The meteorological station and the thermistor chain collected data every 6 seconds and saved averaged data every 5 minutes. All the data were transferred to the central data logger (Campbell Scientific, CR1000, UT, USA), from which users uploaded the data via wireless telemetry to a server. A Self-Contained Autonomous Microstructure Profiler was used to measure and record high resolution profiles of water temperature, conductivity, pressure, and depth in the water column. On deployment, the microprofiler descends from the water surface to the bottom of the lake, resides at the bottom for typically five minutes, and is set in motion from the bottom of the lake to the water surface with an approximate speed range from 0.07 to 0.12 ms-1 while collecting temperature, conductivity, pressure, and time data at 100 Hz. A fast-response FP07 microthermistor measured the temperatures with an approximate accuracy of 0.001oC and time constant of 7 milliseconds. The resulting spatial resolution of the measurements was around 1.0 mm (100 mm/s x 0.01 s). The data from the fast-response micro-conductivity measurement having similar spatial resolution as the temperature were explored to detect the position of AWI since water has nearly 25 times larger thermal conductivity than air at similar temperatures. At the AWI (z=0), the conductivity profile depicted a significant abrupt step change as the SCAMP transitioned from the water phase to the air phase. The time-interval between successive profiles was on average 5 min, and the measurements generally started around 11 am. We report a total of 33 independent measurements in Ramsey lake during the summer of 2018 in July, August, and September. The reported microprofiles consistently depicted higher temperatures on the waterside of air-water interface than in the air above it. -------------------------- SHARING/ACCESS INFORMATION -------------------------- 1. Licenses/restrictions placed on the data:No 2. Links to publications that cite or use the data:No 3. Was data derived from another source?No If yes, list source(s): 4. Terms of Use: Data Repository for the U of Minnesota (DRUM) By using these files, users agree to the Terms of Use. https://conservancy.umn.edu/pages/drum/policies/#terms-of-use --------------------- DATA & FILE OVERVIEW --------------------- 1. File List A. Filename: GRL_Data_Excel_March_10_2022_Submitted.xlsx Short description: Lake temperature and meteorological data. In Figure 1a: u* is the friction velocity estimated using the measured wind speed data at 1.5 m above the lake surface at the lake measuring location (Figure 1a); U10 is the estimated wind speed at 10 m above the lake surface; C10 is the wind surface drag coefficient that was estimated by the empirical function proposed by Lorke and Wüest (2003) at weak wind speeds (U10< 3 ms-1) and by the functional relationship presented by Charnock (1955) at wind speeds (U10> 3 ms-1); is the water temperature gradient estimated at the air-water interface (z=0) by differentiating a 4th order polynomial of measured water temperature versus depth over the depth from surface water temperature (Ts) to the bulk temperature (Tb); qs is the local heat flux estimated by equation (1); δbt is the diffusive thermal sublayer thickness from z=0 (the AWI) to the location defined by the intersection between the temperature gradient in the DTS and Tb; and h is the thickness of actively mixed layer, the lower extent of which was estimated from where the first moving average (over approximately 10 cm increments with 100 data points) temperature below was cooler by 0.02 oC than Tb; is the buoyancy flux, α is the thermal expansion , cp is the specific heat; is the natural convection velocity scale; and date, time (hr:min). Figure 2. Dependence of diffusive thermal sublayer thickness (δbt) on the convective velocity scale (w*). Figure 3. The water temperature difference between surface temperature (Ts) and bulk temperature (Tb) over the diffusive thermal sublayer thickness (δbt) as a function of the ratio of shear velocity scale (u*) at the AWI and convective velocity scale (w*). Figure 4. Dimensionless water temperature microprofiles (T+) versus downward distance (z+) from the air-water interface. The proposed scaling relationship (T+ = 2.1 z+) applies over the diffusive thermal sublayer (DTS) thickness. 2. Relationship between files: N/A -------------------------- METHODOLOGICAL INFORMATION -------------------------- 1. Description of methods used for collection/generation of data: 2. Methods for processing the data: The meteorological station and the thermistor chain collected data every 6 seconds and saved averaged data every 5 minutes. 3. Instrument- or software-specific information needed to interpret the data: All the data were transferred to the central data logger (Campbell Scientific, CR1000, UT, USA), from which users uploaded the data via wireless telemetry to a server. A Self-Contained Autonomous Microstructure Profiler (SCAMP, Precision Measurement Engineering, CA, USA) was used to measure and record high resolution profiles of water temperature, conductivity, pressure, and depth in the water column. 4. Standards and calibration information, if appropriate: NA 5. Environmental/experimental conditions: NA 6. Describe any quality-assurance procedures performed on the data: NA 7. People involved with sample collection, processing, analysis and/or submission: Authors of the manuscript