Cr10x data logger

The outside and inside temperature of the control and GHP-installed pig house was measured using temperature detection sensors with a range of −20 to 80 °C ± 0.2 °C and linked with data loggers (CR10X Data Logger, Campbell Scientific, Edmonton, Canada) and integrated negative temperature coefficient thermistor as sensors. The temperature of the cold and hot water (outflow and inflow) of GHP, heating water tank (inflow and outflow), and water storage tank was measured by using a pipe temperature sensor (GPT-1000, Ginice, Korea), which contains a high-quality thermistor sensing element suitable for use in the range from −50 to 150 °C.
The COP of the GHP was calculated using Equations (1) and (2) [8 (link)].

$\mathrm{COP}=\frac{\mathrm{Heat}\mathrm{absorbed}\left(\mathrm{kW}\right)+\mathrm{Power}\mathrm{consumption}\left(\mathrm{kW}\right)}{\mathrm{Power}\mathrm{consumption}\left(\mathrm{kW}\right)}$
where M = mass flow rate (kgh⁻¹), C_p = Specific heat (Jkg⁻¹K⁻¹), and ΔT = inlet–outlet temperature difference (°C).

Precipitation data were obtained from the Oklahoma Mesonet Station (Washington Station)⁴⁸ located 200 m away from our experiment site, and 12-month version of the standardized precipitation-evapotranspiration index (SPEI-12) was used as annual drought index^{49 (link)}. Air temperature, soil temperature and volumetric soil water content were described in detail previously²⁵ . Specifically, air temperature and soil temperature at the depth of 7.5 cm in the center of each field plot were measured by using Constantan-copper thermocouples wired to a Campbell Scientific CR10x data logger (Campbell Scientific, UT, USA). A portable time domain reflectometer (Soil Moisture Equipment Corp.) was used to measure soil moisture from the soil surface to a 15-cm depth once or twice a month. Three measurements of soil moisture were performed in each plot and the average of three technical replicates were used in further analyses.
All soil samples were analyzed to determine soil total organic carbon (TOC), total nitrogen (TN), soil nitrate (NO₃⁻) and ammonia (NH₄⁺) by the Soil, Water, and Forage Analytical Laboratory at Oklahoma State University (Stillwater, OK, USA). Soil pH was measured using a pH meter with a calibrated combined glass electrode⁵⁰ .

An automated weather station (AWS) was assembled and erected at a standard height of 1.5 m in one of the demonstration plots in Paradys (−29°09′ S, 26.84′ E). The AWS consists of a tipping bucket rain gauge, cup anemometer, wind vane, pyrometer, and combined temperature and humidity sensor. All meteorological data (rainfall, minimum and maximum temperatures, minimum and maximum relative humidity, wind speed and direction, and solar radiation) were recorded on a CR10X data logger (Campbell Scientific, USA) every 5 min and averaged over one hour for storage. The long-term climatic data (2007—to date) were collected from ARC-SCW (Agricultural Research Council of South Africa-Soil, Climate and Water). The rainfall that was recorded from the AWS during the season was collected on a 5 min rainfall amount basis. Therefore, each rain event could constitute several rainstorms and various rainfall durations, which were considered for runoff estimation. As part of farmers’ engagement, manual rain gauges were also installed on each demonstration plot, and farmers monitored and recorded rainfall amounts after the rain events.

After each flux measurement was completed, soil temperature and moisture within the collar were measured at 5 cm depth using a digital thermometer (E.T.I. Ltd., West Sussex, UK) and a Theta probe (ML2, Delta‐T Devices, Cambridge, UK), respectively. In the mire and surrounding lichen heath, 30 dipwells (5 cm diameter PVC tubes) were established and water‐table depth was measured manually during each set of CH₄ measurements. Additionally, weekly measurements of water‐table depth at all locations were made to permit flux modelling. Soil temperature was also monitored continuously (thermistor probe connected to a CR10x datalogger, Campbell Scientific, Leicestershire, UK) within the wetland and birch forest.

Weather stations were established in 1998 at the dry sites at both Barrow and Atqasuk. Readings of temperature at screen height (2 m, 107 temperature probe) and precipitation (35 cm, TE525 tipping bucket rain gage) were taken every 15 min, averaged (temperature) or summed (precipitation), and recorded every hour (CR10X datalogger; the above instruments were produced by Campbell Scientific Inc., Logan, UT). At each of the four sites, two plots were also monitored for soil moisture at 7.5 cm depth (HYD-10-A hydra probe, Stevens Vitel Hydrological and Meteorological Systems, Chantilly, VA). Voltages from the soil moisture probe were recorded every hour and were converted to water fraction by volume (WFV). The focus of the measurements was relative change between years; thus, readings were not calibrated with gravimetric methods. During times prior to the weather station establishment or instrument malfunction, readings from a nearby station were substituted (for details see Hollister et al. 2006 ).