Surface energy fluxes and distribution models of permafrost in European mountain areas: an overview of current developments

In recent years successful attempts have been made to develop and improve s patial modelling of mountain permafrost distribution. Work package 4 of the PACE project (Permafrost and Climate in Europe) sought to provide the esse ntial basis not only of present-day modelling capability, but also of futur e enhancements in modelling methodology. This paper briefly outlines the cu rrently available typology of models, which involve various levels of sophi stication at different spatio-temporal scales. Appropriate models may be ap plied to a range of environmental issues in cold mountain areas, including engineering applications, climate-change scenarios, large-scale mapping, st udies of surface processes or environmental concerns. Special emphasis is g iven here to aspects of energy exchange at the surface and within the activ e layer. Such energy fluxes remain poorly understood but play an essential role in process-oriented research and sensitivity studies with respect to c omplex interactions and feedbacks within the system. In contrast to relativ ely flat permafrost areas in polar and subpolar lowlands, circulation of wa ter and air can cause important lateral fluxes of matter and energy within coarse blocks on steep slopes and result in highly variable and sometimes e xtreme thermal offsets between the ground surface and the permafrost table. Measuring and numerically modelling such fluxes together with coupling tim e-dependent surface and subsurface ground thermal conditions in characteris tic materials (bedrock, ice-rich debris, fine-grained deposits) constitute the main challenge for research in the near future. Copyright (C) 2001 John Wiley & Sons, Ltd.