In recent years successful attempts have been made to develop and improve spatial modelling of mountain permafrost distribution. Work package 4 of the PACE project (Permafrost and Climate in Europe) sought to provide the essential basis not only of present‐day modelling capability, but also of future enhancements in modelling methodology. This paper briefly outlines the currently available typology of models, which involve various levels of sophistication at different spatio‐temporal scales. Appropriate models may be applied to a range of environmental issues in cold mountain areas, including engineering applications, climate‐change scenarios, large‐scale mapping, studies of surface processes or environmental concerns. Special emphasis is given here to aspects of energy exchange at the surface and within the active layer. Such energy fluxes remain poorly understood but play an essential role in process‐oriented research and sensitivity studies with respect to complex interactions and feedbacks within the system. In contrast to relatively flat permafrost areas in polar and subpolar lowlands, circulation of water and air can cause important lateral fluxes of matter and energy within coarse blocks on steep slopes and result in highly variable and sometimes extreme thermal offsets between the ground surface and the permafrost table. Measuring and numerically modelling such fluxes together with coupling time‐dependent surface and subsurface ground thermal conditions in characteristic materials (bedrock, ice‐rich debris, fine‐grained deposits) constitute the main challenge for research in the near future. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉDans ces dernières années, des essais ont, avec succès, développé et amélioré les modélisations spatiales de la distribution du pergélisol de montagne. La quatrième partie du programme PACE (Pergélisol et Climat en Europe) a cherché à établir les bases essentielles, non seulement des possibilités actuelles de modélisation, mais aussi les améliorations méthodologique futures. Le présent article souligne brièvement la typologie couramment disponible des modèles qui comprennent plusieurs niveaux de sophistication à différentes échelles spatio‐temporelles. Des modèles appropriés peuvent être appliqués à de nombreux problèmes environnementaux, entre autres à des applications des ingénieurs, des scénarios de changement de climat, des cartographies à grande échelle, et des études des processus de surface ou environnementaux. Une attention spéciale est accordée ici aux échanges d'énergie à la surface et dans la couche active. De tels flux d'énergie restent mal compris bien qu'ils jouent un rôle essential dans la recherche des processus et dans le domaine des interactions complexes et rétroactives du système. Par opposition à ce qui se passe dans les basses terres polaires et subpolaires, les circulations de l'eau et de l'air peuvent causer des flux importants de matières et d'énergie au sein des blocs grossiers accumulés sur des pentes raides; il en résulte des échanges très variables et parfois extrêmement importants entre la surface du sol et la table du pergélisol.Mesurer et établir des modèles numériques de flux semblables dans des conditions variables de matériaux (roche en place, débris riches en glace, dépôts de granulométrie fine) et en tenant compte des conditions variables dans le temps de la température de surface et du sol, constitue le principal challenge pour la recherche dans le proche avenir Copyright © 2001 John Wiley & Sons, Ltd.
The interaction of energy-exchange processes between the atmosphere and the Earth surface determines the surface temperature regime. It is of fundamental importance to the question whether frozen ground exists at a given site and how rapidly it may decay in response to a climatic perturbation. To further our understanding of these processes, measurements concerning near-surface energy-exchange processes were initiated in January 1997 on creeping permafrost at a high mountain site, Murtèl-Corvatsch, upper Engadin, Swiss Alps. Data on all important energy-balance fluxes were collected. In this paper, we present ground-temperature and energy-balance measurements from Murtèl-Corvatsch for a 2 year period, 1997–99. We will examine the relative importance of the energy-balance components and discuss special problems relating to the coarse surface layer. The results indicate a non-zero energy budget, with a positive deviation of up to 78 W m 4 in winter and a negative deviation of up to –130 W nT2 in summer. We propose that this overall imbalance of the energy-exchange fluxes, as well as the significant difference between mean annual surface and ground temperatures/can be explained by unmeasured advective energy fluxes that occur within the layer of large boulder blocks at the top of the permafrost.
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