The Simulation of Subsurface Effects on the Diurnal Surface Thermal Regime in Cold Regions

Аннотация

... Layered substrate materials are common in nature; these include naturally stratified soils, ice and snow. ... solar radiation penetrates the surface and produces subsurface heating in snow and ice terrain. The stratification problem has been treated by numerous authors as variation of the periodic heat flow problem using surface temperature as the forcing function. ... In recent years there has been a considerable interest in the possibility of acquiring surface environmental information using the spatial variance in the phase and amplitude of the diurnal surface thermal regime as an indicator. ... It would appear that melting rock glacier ice cores, massive ground ice and active layer depth variations contribute significantly to the surface thermal regime variance when these features are relatively close to the surface. It would however appear that lake and sea ice depth variations with either spatially homogeneous light snow cover or none should be detectable particularly where there are large depth variations. Whereas surface climate simulation presents an explicit method of estimating the influence of a wide range of surface environmental factors, specifically albedo, emissivity, substrate radiation extinction (ice and snow), roughness, wetness, stratified thermal properties, slope and exposure, the method would appear to be extremely valuable in the experimental design and hypothesis formation phases of thermal mapping investigations in cold regions. Furthermore as the strategy can be employed to estimate the sensitivity of the surface thermal response to individual environmental factors the method dictates the ground truth requirements for exploratory investigations. Lastly as process and environmental information becomes available the strategy can be used to construct explicit deterministic physical models of the spatial and temporal variance of surface thermal response which can be employed as an analytical portion of a remote sensing reconnaissance system specific to trafficability and site studies in arctic and alpine environments. In short, the capacity for modelling the surface thermal response as a function of the surface and substrate environment vastly increases the accessible information content of thermal infrared maps particularly where these are acquired at several times during the diurnal cycle.