A Sinkhole Field Experiment in the Eastern Alps

O ver the last 25 years, a series of studies has investigated the diurnal formation and destruction cycle of temperature inversions in valleys and basins (for a review see, e.g., Whiteman 1990). In most of the valleys and basins that have been studied to date, advective influences produced by the well-known, diurnally reversing upand down-valley wind systems have greatly complicated the analyses (e.g., Maki and Harimaya 1988; Mori and Kobayashi 1996). Thus, in recent years some investigators have attempted to find experimental locations in mountain areas with sloping terrain where inversion evolution occurs in the presence of upand downslope wind systems, and in the absence of the larger-scale upand down-valley wind systems. An ideal location for these studies would be a naturally confined basin without an outlet stream or river in which a constant-elevation ridgeline completely encircles the basin. Geomorphologic analogs for such an idealized experimental environment include open pit mines, meteor craters, and sinkholes. Sinkholes, which form in many types of terrain, are most frequently found in karst topography where solution of the underlying rock results in the collapse of underground caverns or drainage channels. Idealized small sinkholes or dolines are a natural laboratory for the study of the formation, maintenance, and dissipation of temperature inversions, especially during fair-weather conditions when the sinkholes are isolated from flows aloft by the surrounding mountains and high atmospheric stability. In such conditions, sinkholes and small basins are well known in many parts of the world for producing extreme minimum temperatures, and thus for forming intense inversions. This paper gives an overview of a set of temperature inversion experiments conducted from October 2001 to early June 2002 in a set of limestone sinkholes of different sizes and shapes on Austria’s Hetzkogel Plateau (see Fig. 1). It provides a review of previous and recent experimental studies on this plateau, providing information on the design of the recent A SINKHOLE FIELD EXPERIMENT IN THE EASTERN ALPS