## 5 Changes in Rock Properties with Increasing Freeze-Thaw Cycle  
### Air Temperature Analysis  
In order to examine the freeze-thaw weathering effects on rock properties in the Arctic Circle environment, we collected meteorological field data from Ny-Alesund and analysed the annual air temperature distribution between 2012 and 2017. We used data measured at an Italian base in Ny-Alesund. Given the latitude of the study area (78 deg55'31.65\" N), the summer season in the Ny-Alesund region is very short and relatively temperate, due to the northward movement of the warm Gulf Stream, and the winter season is very cold and long. Between April and August, the Sun does not set, and between November and January, the Sun does not rise. The reason for analysing this meteorological data is because the change in air temperature is the most important factor increasing physical and mechanical damages to rocks due to freeze-thaw cycles [31]. The most basic mediator variable in freeze-thaw damages to rocks is the number of freeze-thaw cycles. This can be determined by the simple method of counting the number of points in a given time interval when the temperature rises above 0 degC [32]. Alternatively, the number of freeze-thaw cycles can be counted by assuming that rocks only freeze when the mean daily temperature is below -3 degC and only thaw when the mean daily temperature is above +1 degC [33]. However, recently, a method has been introduced in which meteorological data is used to analyse the maximum and minimum daily temperatures, and to count the number of freeze-thaw cycles where the temperature goes from above to below 0 degC or below to above 0 degC [31]. In the present study, we used meteorological measurement data to identify cycles in which condensation occurred inside the rocks (the temperature inside the rocks became 0 degC) [31]. We analysed the daily freeze-thaw cycles in terms of minimum and maximum daily air temperatures between 2012 and 2017 and found that freeze-thaw cycles in terms of minimum and maximum daily air temperatures occurred on around 33-62 cycles per year (Figure 3). Figure 4 shows the curves of minimum and maximum daily air temperatures in the study area for year 2015 (at which maximum annual number of freeze-thaw cycle was observed) and year 2017 (at which minimum annual number of freeze-thaw cycle was observed). There are several discontinuities  
Figure 2: Petrographic images of the sample rocks from (**a**) Location A and (**b**) Location B (Qtz = quartz, Do = Dolomite, and Cal = Calcite; left-hand images = crossed polars, right-hand images = parallel polars). in air temperature measurements. The main reasons of the air temperature measurement discontinuities identified in the sites were shortage of power supply and loss or destruction of sensors due to animal trespass. However, we believe that the missing temperature data do not highly influence on estimation of appropriate annual freeze-thaw cycles. As shown in Figure 4, the change in mean maximum and minimum daily temperatures between above and below zero was most severe in April-May and September-October. In the freeze-thaw process for rocks, the surface of the rock freezes (or thaws) when the minimum and maximum daily temperatures alternate from above to below zero (or below to above zero). Therefore, based on the method proposed by [PERSON] et al. [31], we defined one freeze-thaw cycle of the rock surface as the process of the minimum and maximum daily temperature changing from below to above zero or above to below zero. However, freeze-thaw cycles of rock may different from that in terms of daily air temperature. For slight changes of air temperature near 0 \({}^{\circ}\)C may not lead to freeze-thaw cycles of rock. [PERSON] et al. [32] also mentioned that air temperature does not exactly represent the rock surface temperature; however, air temperature can be approximately used to estimate the approximate number of freeze-thaw cycles at the rock surface.