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  • Author or Editor: Johannes Vergeiner x
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Mathias W. Rotach
,
Ivana Stiperski
,
Oliver Fuhrer
,
Brigitta Goger
,
Alexander Gohm
,
Friedrich Obleitner
,
Gabriele Rau
,
Eleni Sfyri
, and
Johannes Vergeiner

Abstract

The flow and turbulence structure in the atmospheric boundary layer over complex mountainous terrain determines Earth–atmosphere interaction, that is, the exchange of energy, mass, and momentum between the surface over such terrain and the free atmosphere. Numerical models for weather and climate, even when operated at high or very high grid resolution, are known to be deficient, leading to inaccurate local forecasts (weather) or scenarios (climate). The nature and reasons for these deficiencies, however, are difficult to assess because systematic and long-term combined observational/modeling studies in mountainous terrain are missing. The Innsbruck Box (i-Box) project aims at filling in this gap through a network of long-term turbulence sites in truly complex terrain, complemented by similarly continuous (surface based) remote sensing and numerical modeling at high to highest [i.e., large-eddy simulation (LES)] resolution. This contribution details the i-Box approach, the experimental design, and available data, as well as the numerical modeling strategy. The first scientific highlights are presented to illustrate the potential of the i-Box data pool and possible future directions.

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Thomas Karl
,
Alexander Gohm
,
Mathias W. Rotach
,
Helen C. Ward
,
Martin Graus
,
Alexander Cede
,
Georg Wohlfahrt
,
Albin Hammerle
,
Maren Haid
,
Martin Tiefengraber
,
Christian Lamprecht
,
Johannes Vergeiner
,
Axel Kreuter
,
Jochen Wagner
, and
Michael Staudinger
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Thomas Karl
,
Alexander Gohm
,
Mathias W. Rotach
,
Helen C. Ward
,
Martin Graus
,
Alexander Cede
,
Georg Wohlfahrt
,
Albin Hammerle
,
Maren Haid
,
Martin Tiefengraber
,
Christian Lamprecht
,
Johannes Vergeiner
,
Axel Kreuter
,
Jochen Wagner
, and
Michael Staudinger

Abstract

The Innsbruck Atmospheric Observatory (IAO) aims to investigate atmospheric chemistry, micrometeorology, and mountain meteorology in a synergistic fashion within an urban setting. A new measurement supersite has been established in order to study processes affecting the exchange of momentum, energy, trace gases, and aerosols in an Alpine urban environment. Various long-term continuous measurements are augmented by frequent focused research campaigns with state-of-the-art instrumentation, linking different classes of data and addressing significant gaps in scientific data availability for urban environments. Current activities seek to address research objectives related to the urban heat island, trace gas emissions, the influence of foehn on air quality, and the atmospheric distribution of trace gases and aerosols in a mountainous city. We present initial results from long-term operations and first highlights from two intensive operational phases, showing that 1) the exchange of greenhouse gas emissions is dominated by anthropogenic activities and is driven by location-specific venting of street canyon air; 2) foehn events significantly perturb the photostationary state indicative for an extensive and rapid airmass exchange of the valley atmosphere; 3) the temporal distribution of pollutants is often decoupled from their emissions and primarily modulated by mountain boundary layer dynamics; 4) we can detect a large number of volatile chemical products in the urban atmosphere, which can be used to fingerprint anthropogenic emission sources; and 5) the first urban carbonyl sulfide (COS) flux measurements point toward anthropogenic emission sources.

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Georg j. Mayr
,
David Plavcan
,
Laurence Armi
,
Andrew Elvidge
,
Branko Grisogono
,
Kristian Horvath
,
Peter Jackson
,
Alfred Neururer
,
Petra Seibert
,
James W. Steenburgh
,
Ivana Stiperski
,
Andrew Sturman
,
Željko Večenaj
,
Johannes Vergeiner
,
Simon Vosper
, and
Günther Zängl

Abstract

Strong winds crossing elevated terrain and descending to its lee occur over mountainous areas worldwide. Winds fulfilling these two criteria are called foehn in this paper although different names exist depending on the region, the sign of the temperature change at onset, and the depth of the overflowing layer. These winds affect the local weather and climate and impact society. Classification is difficult because other wind systems might be superimposed on them or share some characteristics. Additionally, no unanimously agreed-upon name, definition, nor indications for such winds exist. The most trusted classifications have been performed by human experts. A classification experiment for different foehn locations in the Alps and different classifier groups addressed hitherto unanswered questions about the uncertainty of these classifications, their reproducibility, and dependence on the level of expertise. One group consisted of mountain meteorology experts, the other two of master’s degree students who had taken mountain meteorology courses, and a further two of objective algorithms. Sixty periods of 48 h were classified for foehn–no foehn conditions at five Alpine foehn locations. The intra-human-classifier detection varies by about 10 percentage points (interquartile range). Experts and students are nearly indistinguishable. The algorithms are in the range of human classifications. One difficult case appeared twice in order to examine the reproducibility of classified foehn duration, which turned out to be 50% or less. The classification dataset can now serve as a test bed for automatic classification algorithms, which—if successful—eliminate the drawbacks of manual classifications: lack of scalability and reproducibility.

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