Methodology:

Microclimate data was recorded from The Backslope behind Signy Island research station, operated by the British Antarctic Survey, on the South Orkney Islands, Antarctica. Data were automatically recorded for 15 climatic variables on an hourly basis. Variables measured were the following:

Mean air temperature [degrees Celsius]

Mean relative humidity [percentage]

Air pressure [mbar]

Wind speed [m/s]

Wind direction [degrees, N=0 degrees true]

Mean quantum photosynthetically active radiation (QPAR): quantum flux [m-2 s-1 nm-1]

Air temperature ~2.5 cm above ground surface [degrees Celsius] [Logger no. 1]

Mean soil temperature at ~ 0.5cm below surface [degrees Celsius] [Logger no. 2]

Mean soil temperature at ~ 3.5cm below surface [degrees Celsius] [Logger no. 3]

Mean soil temperature at ~ 6.5cm below surface [degrees Celsius] [Logger no. 4]

Mean water content [uSec] just below ground surface

Mean water content [uSec] just below ground surface

Mean water content [uSec] just below ground surface

Mean water content [uSec] just below ground surface

Mean logarithmic temperature [degrees Celsius]

Data collection:

Logger make: Campbell CR1000M

Variables: wind direction. Sensor: Vector W200P. Sensor serial no.: 61719/CV19

Variables: temperature (all depths). Sensor: Campbell 107. Serial no.: JCSL 047394 x4

Variable: soil moisture. Sensor: Campbell CS616. Serial no.: 13932-225 x 4

Variable: relative humidity. Sensor: Campbell CS215. Serial no.: JCSL 047394 x4.

Variable: photosynthetically active radiation. Sensor: Skye SKP215. Serial no.: 47395.

Variable: wind speed. Sensor: A100R. Serial no.: 13140/FHYN

Variable: air pressure. Sensor: Setra 278. Serial no.: 6881397

Please reach out to the Polar Data Centre at PDCServiceDesk@bas.ac.uk if in need of a copy of the Campbell manual.

Data quality:

Due to frost heave, Logger no. 1 has shifted to 2.5cm above the surface of the ground and is thus measuring air temperature. Each subsequent logger is approximately 3 cm below the previous logger, at 0.5, 3.5 and 6.5cm below the surface, respectively. The exact locations of sensors within the soil does change over time due to environmental conditions, so depths recorded are a guide.

Quality control was carried on the data. Specifically, we checked the data for outliers on variables which we concluded followed a normal distribution. A z-score calculation was carried out using the following equation:

abs(x_i - mean(x_month)) / stddev(x_month)

where we took the absolute value of the variable [x_i], then subtracted x_i by the mean of x_i values measured in that month [x_month] (using the DATE column), and then divided over the standard deviation of x_i values measured in that same month [stdev_x_month]. Using values only within the same month was to constrain the calculation to a range of values subject to seasonal variation, that would otherwise yield results that could include, for example, temperatures expected during the summer as well as the winter.

These values were then categorised into three groups: z-scores under 3, between 3-6, and above 6. An additional column was then created alongside each parameter denoting whether the z-score for that value was under 3 (denoted as '1'), between 3 and 6 (denoted as '2'), or above 6 (denoted as '3'). This is to give users the option to filter values in the data that have been flagged as potential outliers based on the z-score calculation above. Z scores were removed for air pressure and wind direction, as these had no z-score groupings besides 1.

Due to the harsh conditions on Signy, data has not been recorded continually across the period. Missing values, where data was not recorded, are included in the dataset.

For columns 'wind speed' and 'wind direction', values of 0 may indicate that the sensor was frozen.

Data have been formatted to 3 decimal places.