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Continuously stratified flows across an Alpine crest with a pass: Shallow and deep föhn
Author(s) -
Armi Laurence,
Mayr Georg J.
Publication year - 2007
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.22
Subject(s) - mesoscale meteorology , geology , radiosonde , stratified flow , stratification (seeds) , stratified flows , hydraulics , meteorology , crest , turbulence , climatology , atmospheric sciences , geography , engineering , seed dormancy , botany , germination , physics , quantum mechanics , dormancy , aerospace engineering , biology
Abstract Shallow and deep Alpine föhn flows are analyzed within the framework of continuously stratified hydraulics. A distinguishing upstream feature of these flows is the presence of stagnant, nearly well‐mixed layers above and beneath the moving stratified fluid. These layers isolate the moving stratified fluid, which has a self‐similar parabolic‐like velocity distribution, from the stratified fluid above and beneath. The shallow and deep realizations of these flows were found on 20 and 21 October 1999 during the Mesoscale Alpine Programme. The temporal evolution from shallow to deep föhn was captured with a sequence of radiosondes, automatic weather stations, an instrumented car, and research aircraft flights. Copyright © 2007 Royal Meteorological Society