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Georg J. Mayr
,
Johannes Vergeiner
, and
Alexander Gohm

Abstract

An instrument package to measure temperature, pressure, humidity, and position was designed to be quickly deployable on any automobile to be used for the study of gap and other orographically influenced flows. Differential GPS (global positioning system) measurements together with a distance counter gave the submeter accuracy of vertical position that was needed for observation of changes in the horizontal pressure field, which is an integral measure of the flow field aloft. A slantwise pressure reduction method was tailored for this application and verified with data from radio soundings. The automobile platform was successfully used during the field phase of the Mesoscale Alpine Programme (MAP) to classify flow states and observe hydraulic jumps in gap flows and to extend aircraft measurements to the ground.

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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
Full access
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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