## 2 Materials and Methods  
### In Situ Meteorological Data  
The Mukhrino field station is located in the central part of West Siberia in the middle taiga bioclimatic zone, 20 km south-west of Khanty-Mansiysk city, on the second terrace of the left bank of the Irtysh River (near the confluence with the Ob River). The Mukhrino field station research area is located in the north-east part of the Mukhrino pristine mire complex which covers a total area \(\sim\)75 km\({}^{2}\)[10]. Hydrometeorological data are available for the Mukhrino field station from 2010 to 2020 for boreal raised peatland in typical microlandscape forms. Data on air temperature, air humidity, atmospheric pressure, wind speed and direction, incoming and outgoing shortwave radiation, net radiation, and soil heat flux were recorded at automated weather stations [49]. An air temperature and humidity probe was covered by a naturally ventilated ROTRONIC AC1000 radiation shield (ROTRONIC, Bassersdorf, Switzerland). An atmospheric pressure sensor was mounted inside the enclosure case for the data logger. Wind speed and direction sensors were installed on a 10 m mast at the ridge site and a 2 m tripod at the hollow site. The distance between the mast and tripod is about 15 m. Net radiation, upward and downward photosynthetically active radiation (PAR) sensors were mounted at each site on a 2 m support crossarm, CM200, with a levelling fixture. Soil temperature at 5 cm depth was measured using an averaging soil thermocouple probe TCAV (Campbell Sci. Inc., Logan, UT, USA). All meteorological variable time series were collected and stored in the data loggers at the weather stations. Several times a year data was manually downloaded, rearranged, and archived at the Yurga State University. The latest data archive (2010-2020) is available for download from Zenodo--[[https://zenodo.org/record/4323024](https://zenodo.org/record/4323024)]([https://zenodo.org/record/4323024](https://zenodo.org/record/4323024)) (accessed on 12 December 2022) [50]. The full list of meteorological variables includes 67 items. The gap filling procedure described in the present article was tested on an eight time series with significantly different temporal dynamics. The meteorological variables are shown at Table 1. The number of available hourly data records for each meteorological variable and data range are also presented. The study period 2010-2021 contains 105,191 hourly time intervals, therefore about one half of the data records are missed. Surface pressure dynamic is characterized by slow changes of values ranging from 965 to 1062 hPa with higher readings in winter due to anticyclonic weather and lower pressure during summer. Air temperature, humidity, and incoming radiation time series have strong diurnal and annual cycles (Figure 1). Wind speed and incoming radiation can only be positive. Wind direction oscillates within the range from 0 to 360 degrees. These physically based restrictions on the data limits are potentially difficult for reproduction by statistical models. Time series of observed meteorological variables are shown in Figure 1 (curve 2). \begin{table}
\begin{tabular}{l l l l l l} \hline
**Id** & **Variable** & **Unit** & \(n\) & **Min** & **Max** \\ \hline Pa & Surface air pressure & hPa & 52,982 & 965 & 1062 \\ Ta & Air temperature at 2 m & \({}^{\circ}\)C & 48,496 & \(-\)40.1 & 34.9 \\ IR & Incoming photosynthetically & \(\mu\)mol/m\({}^{2}\)/s & 47,916 & 0 & 1521 \\ RH & Relative air humidity & kPa & 48,547 & 15.6 & 100 \\ WS & Wind speed at 10 m & m/s & 39,031 & 0 & 15.8 \\ WD & Wind direction at 10 m & deg & 42,186 & 0 & 360 \\ Rn & Net radiation & W/m\({}^{2}\) & 48,549 & \(-\)166 & 669 \\ Ts & Soil temperature at 5 cm & \({}^{\circ}\)C & 46,241 & \(-\)2.6 & 33.0 \\ \hline \end{tabular}
\end{table} 
Table 1: List of meteorological variables from the automated weather station, minimal and maximal observed values, \(n\)—number of available records.