Frost weathering is a major control of rockwall erosion in alpine
environments. Previous frost cracking model approaches used air
temperatures as a proxy for rock temperatures to drive frost weathering
simulations on rockwall and on mountain scale. Unfortunately, the
thermal rockwall regime differs from air temperature due to topographic
effects on insolation and insulation, which affects frost weathering
model results and the resulting erosion patterns. To provide a more
realistic model of the rockwall regime, we installed six temperature
loggers along an altitudinal gradient in the Swiss Alps including two
logger pairs at rockwalls with opposing aspects. We used the recorded
rock surface temperatures to model rock temperatures in the upper 10 m
of the rockwalls and as input data to run four different frost cracking
models. We mapped fracture spacing and rock strength to validate the
model results. Our results showed that frost cracking models are
sensitive to thermal, hydraulic and mechanical parameters that affect
frost cracking magnitude, while frost cracking patterns in terms of peak
location and affected rock mass were consistent. Thermo-mechanical
models incorporate rock strength and hydraulic properties and provided a
frost cracking depth pattern at rockwall scale that reflects better
measured rock strength and fracture spacing of the simulated rock
masses. On mountain scale, these models showed a pattern of increasing
frost cracking with altitude, which is contrary to purely thermal models
but consistent with observations of existing rockfall studies.