Deciphering Freeze–Thaw Dynamics In Rockwalls: A Novel Approach for High Accuracy Regional‐Scale Modeling

Using a large and novel array of instruments on five rockwalls in northern Gaspesia, their respective surface energy balances were calculated and their thermal regimes were measured and modeled to depths exceeding the seasonal frost penetration. A parametric analysis of the thermal properties and structural characteristics of the instrumented rockwalls was then performed. The roles of solar radiation exposure, surface thermal absorptivity, lithology, and fracture pattern on the distribution of episodic freeze–thaw cycles and on the seasonal frost distribution over a winter were quantified. The fine spatiotemporal scale of our measurements and models revealed complex thermal configurations in the first meters of rockwalls, including frozen layers sandwiched between thawed ones and vice versa. Freeze–thaw cycle frequency was primarily driven by solar radiation exposure and surface absorptivity, while seasonal frost penetration was strongly influenced by lithology and fracture pattern. The parametric analysis based on thermal and structural properties representative of the study area enabled us to extrapolate a local thermal regime model to a regional scale without needing to instrument as many sites as there is diversity in exposure, absorptivity, lithology, and fracture patterns. Other parameters, such as slope inclination, snow accumulation, and climate warming, can also be tested with this approach. This hybrid method, which combines field measurements and modeling, is intended to quantify the thermal regime of multiple rockwalls more accurately than spatial modeling and climate reanalyzes, while drastically reducing the effort, cost, and risk of conventional instrumentation. It could represent a valuable tool for regional hazard management strategies.