The thermal regime of the active layer at the Murtèl rock glacier based on data from 2002

Active layer temperatures are presented from a rock glacier in the Swiss Alps. The data represent a full year (2002) covering parts of two very different winters. Winter/spring 2002 was very cold and dry; fall 2002 was characterized by an unusual amount of snow. Active layer temperatures are examined together with climate data and are used to discuss the processes which control the thermal regime of an active layer on a slope of a bouldery rock glacier surface. The development of the snow cover as well as the snow depth are shown to be essential, but the non‐linear heating of the bouldery material with increasing air temperatures and the micro‐topography of the rock glacier surface are also shown to have an influence on the thermal regime of the active layer. Furthermore, it is shown that the advective air movement within the blocky deposit has much less influence on the thermal regime than the vertical displacement of air masses. This is contradicts earlier literature on the subject. Copyright © 2004 John Wiley & Sons, Ltd.