Title --- thermistor_harp.csv Authors --- Eli Schwat Lead and corresponding author Graduate student 301-651-3959 Civil and Environmental Engineering University of Washington 201 More Hall, Box 352700 Seattle, WA 98195-2700 https://orcid.org/0000-0003-1212-5735 elilouis@uw.edu Daniel Hogan https://orcid.org/0009-0008-0553-6783 dlhogan@uw.edu Civil and Environmental Engineering, University of Washington Jessica Lundquist https://orcid.org/0000-0003-2193-5633 jdlund@uw.edu Civil and Environmental Engineering, University of Washington Ethan Gutmann https://orcid.org/0000-0003-4077-3430 gutmann@ucar.edu National Center for Atmospheric Research: Boulder, CO Julie Vano jvano@agci.org Aspen Global Change Institute Dataset Description --- **Introduction** This dataset contains measurements from 8 thermistors vertically spaced 5 millimeters apart on two faces of a "thermistor harp", a triangular prism frame 3D-printed with polylactic acid (PLA) filaments in the color white. The frame structure allows strings to be tied horizontally at 5 millimeters spacing. Wire thermistors are tied to those strings so that thermistors measure temperature every 5 millimeters vertically. The wire thermistors are connected to an NCAR data logger which provides mean temperature measurements at 5 second intervals. The raw output has been processed into the CSV dataset. The CSV dataset has data collections from 4 different days, each data collection lasted between 50 seconds and 2 hours. Some of the data collections began with the thermistor harp inside a temperature controlled building, these parts of the dataset can be identified by the above 0˚C measurements. Once the harp was placed outside, on top of snow, the temperatures decreased to below 0˚C. Measurements should be used from times after the thermistor harp has adjusted to the outside temperatures. **Data version number and date** Version 0, 2023-09-18 **Data Status (Preliminary or Final)** Final **Time period covered by the data** 2023-02-03, 20:00:00 - 20:00:50 2023-02-04, 20:00:00 - 20:03:30 2023-03-06, 18:45:00 - 20:40:55 2023-03-07, 18:44:00 - 19:44:25 **Physical location** Latitude/Longitude: 38.958892, -106.989812 Elevation: 2894 meters **Data Frequency** 5 second Instrument Description --- A triangular prism frame, or "thermistor harp", supports the mounting of 8 wire thermistors. Two faces of the prism hold 4 thermistors each. One a single face, thermistors are spaced 10 millimeters apart. The mounting locations on each face are offset by 5 millimeters, such that thermistors from the two faces collectively record temperature measurements spaced 5 millimeters apart. On one face, thermistors are located at 0mm, 10mm, 20mm, 30mm. One the other face, thermistors are located at 5mm, 15mm, 25mm, and 35mm. The thermistors attached are Amphenol NTC interchangeable Thermistor Series Type SC30 or SC50. 2 sets of 4 thermistors are used on the instrument. The manufacturer provides an estimate of accuracy as ±0.10˚C. https://www.amphenol-sensors.com/hubfs/Documents/AAS-920-307E-Thermometrics-NTC-Type-SC3050-021518-web.pdf Thermistors were calibrated by NCAR using an ice-water bath. The NCAR data logger has a resolution of 1-second and data is reported as 5-second averages. Data Collection and Processing --- Data collection was performed at the Gothic townsite in the East River Valley of Colorado. Data collection generally began inside. After data recording began, the thermistor was transferred outside and placed on the snow. The thermistor harp was pushed into the snow such that the lowest thermistor made contact with the snow surface and recorded the temperature of the snow surface. No derived parameters, processing techniques, quality assurance, or quality control procedures were applied to this dataset. Data Format --- The dataset is provided as a comma-delimited text file (csv). Five columns are included in the file. *time_seconds* - records the time relative to the beginning of data collection in seconds *side* - "low" or "high". indicates which of the two faces of the thermistor harp the measurement is collected on. See the "Instrument Description" section. *temperature* - temperature measured in degrees Celsius. *height* - height above the lowest thermistor. in units of millimeters. *time* - local date and time of data collection, in the format yyyy-mm-dd HH:MM:SS. Data Remarks --- Data collections from different days are combined in the single CSV file. Data collection using the thermistors was frequently interrupted due to failure of the data logger components in extreme cold conditions (near -20˚C). Bluetooth connectivity failed after a minute of exposure to the cold temperatures. The dataset includes collections from two days (2023-02-03 and 2023-02-04) during which bluetooth connectivity failed and data collection was cut short (on each day, only about 1 minute of data was collected when the instrument was placed outside). On two additional days of data collection (2023-03-06 and 2023-03-07), we used a 50 foot USB cable to connect a computer directly to the data logger box. Without reliance on the bluetooth chip, we had successful data collection for multiple hours. Note that for three of the four days of data collection (2023-02-04, 2023-03-06, 2023-03-07), data collection began inside a temperature controlled building. Data from these days have temperatures well above ˚C (10-20˚C) and all of these temperatures represent temperatures inside. After beginning data collection, the instrument was moved outside. Temperature quickly drop to well below 0˚C (-10 to -20˚C). Data during the transition period (thermistors cooling) should be removed for analysis of vertical temperature measurements. References --- The creation of this instrument was inspired by this study: https://doi.org/10.2307/520053. Appendix --- GCMD science keywords: snow, snow energy balance, air temperature, boundary layer temperature