Inversion Build-Up and Cold-Air Outflow in a Small Alpine Sinkhole

Author(s)
Manuela Lehner, C. David Whiteman, Manfred Dorninger
Abstract

Semi-idealized model simulations are made of the nocturnal cold-air pool development in the approximately 1-km wide and 100–200-m deep Grünloch basin, Austria. The simulations show qualitatively good agreement with vertical temperature and wind profiles and surface measurements collected during a meteorological field expedition. A two-layer stable atmosphere forms in the basin, with a very strong inversion in the lowest part, below the approximate height of the lowest gap in the surrounding orography. The upper part of the stable layer is less strongly stratified and extends to the approximate height of the second-lowest gap. The basin atmosphere cools most strongly during the first few hours of the night, after which temperatures decrease only slowly. An outflow of air forms through the lowest gap in the surrounding orography. The outflow connects with a weak inflow of air through a gap on the opposite sidewall, forming a vertically and horizontally confined jet over the basin. Basin cooling shows strong sensitivity to surface-layer characteristics, highlighting the large impact of variations in vegetation and soil cover on cold-air pool development, as well as the importance of surface-layer parametrization in numerical simulations of cold-air-pool development.

Organisation(s)
Department of Meteorology and Geophysics
External organisation(s)
University of Utah, Leopold-Franzens-Universität Innsbruck
Journal
Boundary-Layer Meteorology
Volume
163
Pages
497–522
ISSN
0006-8314
DOI
https://doi.org/10.1007/s10546-017-0232-7
Publication date
01-2017
Peer reviewed
Yes
Austrian Fields of Science 2012
105206 Meteorology
Keywords
ASJC Scopus subject areas
Atmospheric Science
Portal url
https://ucris.univie.ac.at/portal/en/publications/inversion-buildup-and-coldair-outflow-in-a-small-alpine-sinkhole(7891361f-1ef4-4024-a7dc-3d53ed12cbf8).html