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and the results of the wind tunnel tests were compared with the observation results. [PERSON] (1984) [2] conducted wind tunnel tests of different sizes of snow fences and pointed out that the limit of the Froude number can be relaxed. This study also proposed a time similarity criterion based on snow flux. [PERSON] et al. (1998) [3] proposed a similarity criterion focusing on the similarity of the final drift snow volume and simulated the snow distribution around the Concordia Scientific Research Station in Antarctica by spraying artificial snow particles with a snow gun in the Jules Verne climate wind tunnel in France. [PERSON] and [PERSON] (2003) [4] measured the snow distribution around the scaled model of the SANAE IV research station in Antarctica, especially in the wake region, and the influence of similarity criteria was discussed. [PERSON] et al. (2012) [5] conducted snow blowing tests on flat snow surfaces in a wind tunnel, and pointed out that the influence of snow particles on the wind field cannot be ignored in the saltation layer. [PERSON] et al. (2013) [6] measured the velocity of saltating snow particles by using PIV measurements. Although the studies mentioned above provided a deep investigation of the test particles and similarity criteria, they mainly focused on snowdrifts on the ground. Currently, there are fewer experimental studies of snowdrift on building roofs. [PERSON] and [PERSON] (1990) [7] used bran as substitute particles to carry out wind tunnel tests with different wind velocities and terrain roughness for stepped flat roofs. It was pointed out that the main factor affecting the snow distribution in rough terrain is the surrounding environment rather than particles' saltation. [PERSON] et al. (2002) [8] measured the wind velocity on the surface of a stepped roof through a wind tunnel test, then analyzed the relationship between the wind velocity and the snow depth obtained by field observation. A negative correlation between the snow depth and the acceleration of the wind velocity near the roof was detected, which was consistent with the result derived by [PERSON] et al. (1996) [9]. [PERSON] et al. (2004) [10] adopted crushed walnut to conduct water flume tests on a double pitched roof and a stepped flat roof, pointing out the feasibility of a water flume test. [PERSON] et al. (2014) [11] conducted wind tunnel tests with three kinds of particles, and the results were compared with field observations conducted by [PERSON] et al. (2002) [8]. The best results can be obtained when silica sand is used as the substitute particles, thus fine silica sand was also used as substitute particles in this paper, although some similar criteria were not satisfied due to the limitation of the particle properties. [PERSON] et al. (2016) [12] conducted a wind tunnel test of snowdrifts on a flat roof using the same method as the reference [11]. The wind tunnel test was combined with the CFD (computational fluid  
Figure 1: Three-dimensional model of snow distributions on a group of buildings in Harbin, China. dynamics) numerical simulation by considering the repose angle of snow particles. Both results show favorable agreement. It should be pointed out that scant studies investigating the snow load interference effect have been done. [PERSON] and [PERSON] (2019)[PERSON] et al. (2019) performed wind tunnel tests of the snow load distribution on three different large-sized stadium roofs by using powdered polystyrene foam as artificial snow, and the interference effect between the investigated object and its surroundings was pointed out. [PERSON] and [PERSON] (2008)[PERSON] and [PERSON] (2008) simulated the snowdrifts around three adjacent elevated buildings and compared the results with field observations. Overall, the prediction results corresponded well with the actual snowdrift pattern. [PERSON] and [PERSON] (2015)[PERSON] and [PERSON] (2015) investigated the snow deposition around three different geometrical configurations of pillars using the CFD method.