Climatic implications of cirque distribution in the Romanian Carpathians: Palaeowind directions during glacial periods

摘要

The many glacial cirques in the mountains of Romania indicate the distribution of former glacier sources, related to former climates as well as to topography. In the Transylvanian Alps (Southern Carpathians) cirque floors rise eastward at 0.714 m km~(-1), and cirque aspects tend ENE, confirming the importance of winds from some westerly direction. There is a contrast between two neighbouring ranges: the Fǎgǎra?, where the favoured aspect of cirques is ENE, and the Iezer, where the tendency is stronger and to NNE. This can be explained by the Iezer Mountains being sheltered by the Fǎgǎra?, which implies precipitation-bearing winds from north of west at times of mountain glaciation. Palaeoglaciation levels also suggest winds from north of west, which is consistent with aeolian evidence from Pleistocene dunes, yardangs and loess features in the plains of Hungary and southwestern Romania. In northern Romania (including Ukrainian Maramure?) the influence of west winds was important, but sufficient only to give a northeastward tendency in cirque aspects. This gave stronger asymmetry than in the Transylvanian Alps, as the northward (solar radiation incidence) tendency in these marginally glaciated mountains was less diluted by wind effects. Cirque floors in northern Romania are lower also in northeast-facing cirques. In general, cirque aspects result from several factors and the mean tendency is not downwind, but is displaced from poleward by wind and by minor effects.